feat(sandbox): cross-family file sandbox — one policy home, sandboxed fs provider, fs escalation parity

Extend SandboxMode enforcement from bash to the filesystem tools, the sandbox
RFC's deferred cross-family phase.

- dsh-sandbox-policy (new, ctx.sandboxPolicy): the single home for the
  deployment default mode + workspaceRoot and the per-session override event,
  renamed bash/sandbox-mode -> sandbox/mode and moved here with its fold/setter.
  Decouples the bash seam from dsh-session.
- dsh-fs-sandbox (new): SandboxedFileSystem extends LocalFileSystem and fences
  write/edit by the per-call mode (read-only denies, workspace-write contains to
  the workspace + temp roots via the shared writableRoots, danger passes
  through); reads pass through. Structured FS_SANDBOX_DENIED; in-lock parent
  re-canonicalization. A policy fence in trusted code, not a kernel boundary.
- dsh-sandbox: the shared escalation kit (writableRoots, the strictly-wider
  ladder, denial/hint markers, approveEscalation) both tool families use;
  approveEscalation takes a structural approver so dsh-sandbox gains no
  approval/agent dependency, and both tools stay duplication-free.
- tool-fs: write/edit advertise sandbox_permissions/justification under a
  confining ctx.fs, map FS_SANDBOX_DENIED to the shared [sandbox: ...] marker,
  and resolve the same one-approved-wider retry.
- examples/acp-agent: composes sandbox-policy + fs-sandbox, drops the gating
  that disabled the fs stack under confined modes.

RFC docs/rfc/implemented/feature/2026-07-14-cross-family-fs-sandbox.md; the old
sandbox RFC's In-process/deferred/FAQ sections updated to shipped fact.

docs/architecture.md

@@ -26,6 +26,7 @@ A harness is one [Cordis](cordis-primer.md) context. Packages contribute service
 | `ctx.llm` | [`llm/`](../packages/llm/README.md) | adapter registry and streaming model calls |
 | `ctx.bash` | [`bash/`](../packages/bash/README.md) | foreground/background command execution |
 | `ctx.sandbox` | [`sandbox/`](../packages/sandbox/README.md) | same-world process confinement (argv wrapping, per-call policy) |
+| `ctx.sandboxPolicy` | [`sandbox/`](../packages/sandbox/README.md) | shared sandbox policy: mode, workspace root, per-session override |
 | `ctx.codeRuntime` | [`code-runtime/`](../packages/code-runtime/README.md) | model-written program execution |
 | `ctx.fs` | [`fs/`](../packages/fs/README.md) | filesystem provider primitives and policy events |
 | `ctx.skills` | [`skill/`](../packages/skill/README.md) | skill provider registry and progressive disclosure |

docs/capability-seams.md

@@ -56,6 +56,8 @@ flowchart LR
   pkg_sandbox["sandbox"]
   svc_sandbox["ctx.sandbox<br/>Process-sandbox seam"]
   pkg_sandbox_local["sandbox-local"]
+  svc_sandboxPolicy["ctx.sandboxPolicy<br/>Sandbox policy home"]
+  pkg_fs_sandbox["fs-sandbox"]
   pkg_approval["approval"]
   svc_approval["ctx.approval<br/>Approval seam"]
   pkg_permission["permission"]
@@ -99,12 +101,14 @@ flowchart LR
   pkg_compact_basic --> svc_compact
   pkg_fs --> svc_fs
   pkg_fs_local --> svc_fs
+  pkg_fs_sandbox --> svc_fs
   pkg_llm --> svc_llm
   pkg_llm_deepseek --> svc_llm
   pkg_llm_pi_ai --> svc_llm
   pkg_llm_replay --> svc_llm
   pkg_permission --> svc_permission
   pkg_sandbox --> svc_sandbox
+  pkg_sandbox --> svc_sandboxPolicy
   pkg_sandbox_local --> svc_sandbox
   pkg_session --> svc_sessions
   pkg_session_persistence --> svc_sessionPersistence
@@ -147,6 +151,10 @@ flowchart LR
   svc_llm --> pkg_compact_basic
   svc_permission --> pkg_acp
   svc_sandbox --> pkg_bash_sandbox
+  svc_sandboxPolicy --> pkg_bash_sandbox
+  svc_sandboxPolicy --> pkg_fs_sandbox
+  svc_sandboxPolicy --> pkg_tool_bash
+  svc_sandboxPolicy --> pkg_tool_fs
   svc_sessionPersistence --> pkg_acp
   svc_sessionPersistence --> pkg_agent_loop
   svc_sessionPersistence --> pkg_session_query
@@ -194,10 +202,11 @@ flowchart LR
 | `ctx.agentLoop` | `bundle` | [`agent-loop`](../packages/core/agent-loop) | - | [`agent-core`](../packages/core/agent-core) | - | The one concrete loop plugin; extension packages depend on dsh-agent events and services, not on this package. |
 | `ctx.bash` | `seam` | [`bash`](../packages/bash/bash) | [`bash-local`](../packages/bash/bash-local), [`bash-sandbox`](../packages/bash/bash-sandbox) | [`tool-bash`](../packages/bash/tool-bash), [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) | - | The model-facing bash tools and hook bridges consume this seam; sandboxed or remote executors replace bash-local without touching them. |
 | `ctx.sandbox` | `seam` | [`sandbox`](../packages/sandbox/sandbox) | [`sandbox-local`](../packages/sandbox/sandbox-local) | [`bash-sandbox`](../packages/bash/bash-sandbox) | - | Consumers hand over the exact argv they are about to spawn; same-world backends wrap it under a per-call policy and report enforcement. |
+| `ctx.sandboxPolicy` | `core` | [`sandbox`](../packages/sandbox/sandbox) | - | [`bash-sandbox`](../packages/bash/bash-sandbox), [`fs-sandbox`](../packages/fs/fs-sandbox), [`tool-bash`](../packages/bash/tool-bash), [`tool-fs`](../packages/fs/tool-fs) | - | The one home for the deployment default mode + workspace root and the per-session `sandbox/mode` override; both enforcing families read it so bash and fs cannot confine to different roots. |
 | `ctx.approval` | `seam` | `approval` | [`acp`](../packages/ui/acp) | [`tools`](../packages/core/tools), [`tool-bash`](../packages/bash/tool-bash) | - | One-shot permission decisions dispatched over the `approval/request` waterfall; answerers are listeners (the ACP bridge for its own agents), absence fails closed to `unavailable`. |
 | `ctx.permission` | `core` | [`permission`](../packages/ui/permission) | - | [`acp`](../packages/ui/acp) | - | User-facing preset table (`workspace-write`/`danger-full-access`) bundling the sandbox-mode and approval-policy knobs; a switch writes one `permission/preset` event through to both knob events. |
 | `ctx.codeRuntime` | `seam` | [`code-runtime`](../packages/code-runtime/code-runtime) | [`code-runtime-worker`](../packages/code-runtime/code-runtime-worker) | [`tools`](../packages/core/tools) | - | Runs one model-written program against host-provided async bindings; backends differ by substrate and language (the tool registry consumes it for Code Mode). |
-| `ctx.fs` | `seam` | [`fs`](../packages/fs/fs) | [`fs-local`](../packages/fs/fs-local) | [`tool-fs`](../packages/fs/tool-fs) | [`fs-policy`](../packages/fs/fs-policy) | tool-fs executes read/write/edit through ctx.fs; fs-policy contributes observed-state checks through the fs/* event gate. |
+| `ctx.fs` | `seam` | [`fs`](../packages/fs/fs) | [`fs-local`](../packages/fs/fs-local), [`fs-sandbox`](../packages/fs/fs-sandbox) | [`tool-fs`](../packages/fs/tool-fs) | [`fs-policy`](../packages/fs/fs-policy) | tool-fs executes read/write/edit through ctx.fs; fs-sandbox fences mutations by the shared sandbox mode; fs-policy contributes observed-state checks through the fs/* event gate. |
 | `ctx.compact` | `seam` | [`compact`](../packages/compact/compact) | [`compact-basic`](../packages/compact/compact-basic) | [`compact-basic`](../packages/compact/compact-basic) | - | The basic backend currently consumes the pre-step event directly; a model-facing compact tool remains deferred. |
 | `ctx.subagents` | `seam` | [`subagent`](../packages/subagent/subagent) | [`subagent-spawn`](../packages/subagent/subagent-spawn), [`subagent-fork`](../packages/subagent/subagent-fork), [`subagent-acp`](../packages/subagent/subagent-acp), [`subagent-mock`](../packages/support/subagent-mock) | [`tool-subagent`](../packages/subagent/tool-subagent) | - | Providers implement transports; tool-subagent exposes one configured provider as a model-facing tool name. |
 | `ctx.web` | `seam` | [`web`](../packages/web/web) | [`web-search-exa`](../packages/web/web-search-exa), [`web-search-perplexity`](../packages/web/web-search-perplexity), [`web-search-deepseek`](../packages/web/web-search-deepseek), [`web-fetch-local`](../packages/web/web-fetch-local) | [`tool-web`](../packages/web/tool-web) | - | Search and fetch providers register into one ctx.web seam; tool-web owns the stable model-facing names. |

docs/config-catalog.md

@@ -153,28 +153,21 @@ Source: [`packages/bash/bash-local/src/index.ts:29`](../packages/bash/bash-local
 
 ## `@deepseek-ai/dsh-bash-sandbox`
 
-Requires: `sandbox`
+Requires: `sandbox` · `sandboxPolicy`
 
 ```ts config-catalog
 /**
- * Plugin config: the local executor's knobs plus the sandbox policy. All
- * optional — `static Config` supplies the defaults (`mode: 'read-only'` is the
- * fail-safe default; an example that wants a workspace-writable agent opts in
- * explicitly). The runner choice is NOT configured here: which platform
- * backend confines the command is the `ctx.sandbox` provider's config.
+ * Plugin config: the local executor's knobs, verbatim. The sandbox policy —
+ * the default mode and the `workspace-write` boundary root — is NOT here: it
+ * lives on `ctx.sandboxPolicy` (`@deepseek-ai/dsh-sandbox-policy`), the one
+ * home both enforcing families read, so bash and fs can never confine to
+ * different roots. The runner choice is likewise the `ctx.sandbox` provider's
+ * config, not this executor's.
  */
-export interface Config extends LocalConfig {
-  /** File-sandbox mode commands run under (default: `read-only`). */
-  mode?: SandboxMode
-  /**
-   * Root directory `workspace-write` mode may write under (default: the
-   * executor's default working directory — `cwd`, else `process.cwd()`).
-   */
-  workspaceRoot?: string
-}
+export type Config = LocalConfig
 ```
 
-Depends on: [`LocalConfig`](#deepseek-aidsh-bash-local) · [`SandboxMode`](core-data-structures/sandbox.md)
+Depends on: [`LocalConfig`](#deepseek-aidsh-bash-local)
 
 Source: [`packages/bash/bash-sandbox/src/index.ts:60`](../packages/bash/bash-sandbox/src/index.ts)
 
@@ -267,6 +260,24 @@ export interface Config {
 
 Source: [`packages/fs/fs-local/src/index.ts:58`](../packages/fs/fs-local/src/index.ts)
 
+## `@deepseek-ai/dsh-fs-sandbox`
+
+Requires: `sandboxPolicy`
+
+```ts config-catalog
+/**
+ * Plugin config: the local backend's knobs, verbatim (only `cwd`, the resolve
+ * base for relative paths). The sandbox default (mode + `workspace-write`
+ * boundary root) is NOT here — it lives on `ctx.sandboxPolicy`, the one home
+ * both enforcing families share.
+ */
+export type Config = LocalConfig
+```
+
+Depends on: [`LocalConfig`](#deepseek-aidsh-fs-local)
+
+Source: [`packages/fs/fs-sandbox/src/index.ts:49`](../packages/fs/fs-sandbox/src/index.ts)
+
 ## `@deepseek-ai/dsh-hooks-claude`
 
 Requires: `bash`
@@ -464,7 +475,7 @@ export interface Config {
  * runs under while the preset is active — plus its presentation.
  */
 export interface PresetSpec {
-  /** The `bash/sandbox-mode` value the preset writes through. */
+  /** The `sandbox/mode` value the preset writes through. */
   sandbox: SandboxMode
   /** The `approval/policy` value the preset writes through. */
   approval: ApprovalPolicy
@@ -477,7 +488,7 @@ export interface PresetSpec {
 
 Depends on: [`ApprovalPolicy`](core-data-structures/approval.md) · [`SandboxMode`](core-data-structures/sandbox.md)
 
-Source: [`packages/ui/permission/src/index.ts:97`](../packages/ui/permission/src/index.ts)
+Source: [`packages/ui/permission/src/index.ts:100`](../packages/ui/permission/src/index.ts)
 
 ## `@deepseek-ai/dsh-repeat-tool-guard`
 
@@ -558,6 +569,31 @@ export interface Config {
 
 Source: [`packages/sandbox/sandbox-local/src/index.ts:36`](../packages/sandbox/sandbox-local/src/index.ts)
 
+## `@deepseek-ai/dsh-sandbox-policy`
+
+```ts config-catalog
+/**
+ * Plugin config: the deployment's sandbox default. All optional — `Config`
+ * supplies the defaults (`mode: 'read-only'` is the fail-safe default; a
+ * deployment that wants a workspace-writable agent opts in explicitly). The
+ * runner choice is NOT here (it is the `ctx.sandbox` provider's config), nor
+ * is any per-family knob: this is the one shared policy home.
+ */
+export interface Config {
+  /** File-sandbox mode a session starts from (default: `read-only`). */
+  mode?: SandboxMode
+  /**
+   * Absolute root directory `workspace-write` may write under (default:
+   * `process.cwd()`). Both enforcing families fence against this SAME root.
+   */
+  workspaceRoot?: string
+}
+```
+
+Depends on: [`SandboxMode`](core-data-structures/sandbox.md)
+
+Source: [`packages/sandbox/sandbox-policy/src/index.ts:44`](../packages/sandbox/sandbox-policy/src/index.ts)
+
 ## `@deepseek-ai/dsh-session-persistence-jsonl`
 
 Requires: `sessions`
@@ -900,7 +936,7 @@ export interface Config {
 }
 ```
 
-Source: [`packages/fs/tool-fs/src/index.ts:48`](../packages/fs/tool-fs/src/index.ts)
+Source: [`packages/fs/tool-fs/src/index.ts:52`](../packages/fs/tool-fs/src/index.ts)
 
 ## `@deepseek-ai/dsh-tool-skill`
 

docs/cordis-catalog/events.md

@@ -201,7 +201,7 @@ Single-slot decision: produce the optional version guard for the next FileSystem
 
 Types: [FsTarget](../core-data-structures/filesystem.md) · [FsVersion](../core-data-structures/filesystem.md)
 
-Source: [`packages/fs/fs/src/index.ts:123`](../../packages/fs/fs/src/index.ts)
+Source: [`packages/fs/fs/src/index.ts:124`](../../packages/fs/fs/src/index.ts)
 
 ### `fs/observed` — emit
 
@@ -213,7 +213,7 @@ Record that an actor observed a target at a version, after a successful read/wri
 
 Types: [FsTarget](../core-data-structures/filesystem.md) · [FsVersion](../core-data-structures/filesystem.md)
 
-Source: [`packages/fs/fs/src/index.ts:138`](../../packages/fs/fs/src/index.ts)
+Source: [`packages/fs/fs/src/index.ts:139`](../../packages/fs/fs/src/index.ts)
 
 ### `fs/write-intent` — waterfall
 
@@ -225,7 +225,7 @@ Single-slot decision: produce the write intent for the next FileSystem.writeText
 
 Types: [FsTarget](../core-data-structures/filesystem.md) · [FsWriteIntent](../core-data-structures/filesystem.md)
 
-Source: [`packages/fs/fs/src/index.ts:109`](../../packages/fs/fs/src/index.ts)
+Source: [`packages/fs/fs/src/index.ts:110`](../../packages/fs/fs/src/index.ts)
 
 ## `llm/*`
 

docs/cordis-catalog/services.md

@@ -79,7 +79,7 @@ onTaskDone(listener: BashTaskListener): () => void
 
 Types: [BashExecRequest](../core-data-structures/bash.md) · [BashExecSpec](../core-data-structures/bash.md) · [BashRunResult](../core-data-structures/bash.md) · [BashTask](../core-data-structures/bash.md) · [BashTaskRead](../core-data-structures/bash.md)
 
-Source: [`packages/bash/bash/src/index.ts:62`](../../packages/bash/bash/src/index.ts)
+Source: [`packages/bash/bash/src/index.ts:61`](../../packages/bash/bash/src/index.ts)
 
 ## `ctx.codeRuntime` — `CodeRuntime` (abstract seam)
 
@@ -139,13 +139,13 @@ abstract stat(target: FsTarget, signal?: AbortSignal): Promise<FsInfo | undefine
 abstract readText(target: FsTarget, signal?: AbortSignal): Promise<string>
 abstract streamText(target: FsTarget, signal?: AbortSignal): Promise<AsyncIterable<string>>
 abstract listDir(target: FsTarget, signal?: AbortSignal): Promise<FsDirEntry[]>
-abstract writeText(target: FsTarget, content: string, expected?: FsWriteIntent, signal?: AbortSignal): Promise<FsWriteOutcome>
-abstract editText(target: FsTarget, edit: FsEditRequest, expected?: { version: FsVersion }, signal?: AbortSignal): Promise<FsEditOutcome>
+abstract writeText( target: FsTarget, content: string, expected?: FsWriteIntent, signal?: AbortSignal, sandboxMode?: SandboxMode, ): Promise<FsWriteOutcome>
+abstract editText( target: FsTarget, edit: FsEditRequest, expected?: { version: FsVersion }, signal?: AbortSignal, sandboxMode?: SandboxMode, ): Promise<FsEditOutcome>
 ```
 
-Types: [FsEditOutcome](../core-data-structures/filesystem.md) · [FsEditRequest](../core-data-structures/filesystem.md) · [FsInfo](../core-data-structures/filesystem.md) · [FsTarget](../core-data-structures/filesystem.md) · [FsVersion](../core-data-structures/filesystem.md) · [FsWriteIntent](../core-data-structures/filesystem.md) · [FsWriteOutcome](../core-data-structures/filesystem.md)
+Types: [FsEditOutcome](../core-data-structures/filesystem.md) · [FsEditRequest](../core-data-structures/filesystem.md) · [FsInfo](../core-data-structures/filesystem.md) · [FsTarget](../core-data-structures/filesystem.md) · [FsVersion](../core-data-structures/filesystem.md) · [FsWriteIntent](../core-data-structures/filesystem.md) · [FsWriteOutcome](../core-data-structures/filesystem.md) · [SandboxMode](../core-data-structures/sandbox.md)
 
-Source: [`packages/fs/fs/src/index.ts:172`](../../packages/fs/fs/src/index.ts)
+Source: [`packages/fs/fs/src/index.ts:173`](../../packages/fs/fs/src/index.ts)
 
 ## `ctx.llm` — `LlmService`
 
@@ -174,7 +174,7 @@ set(session: Session, name: string): void
 
 Types: [SessionEvent](../core-data-structures/core.md)
 
-Source: [`packages/ui/permission/src/index.ts:115`](../../packages/ui/permission/src/index.ts)
+Source: [`packages/ui/permission/src/index.ts:118`](../../packages/ui/permission/src/index.ts)
 
 ## `ctx.sandbox` — `SandboxProvider` (abstract seam)
 
@@ -192,7 +192,13 @@ abstract confine(argv: readonly string[], policy: SandboxPolicy): ConfinedArgv
 
 Types: [ConfinedArgv](../core-data-structures/sandbox.md) · [SandboxPolicy](../core-data-structures/sandbox.md)
 
-Source: [`packages/sandbox/sandbox/src/index.ts:180`](../../packages/sandbox/sandbox/src/index.ts)
+Source: [`packages/sandbox/sandbox/src/index.ts:191`](../../packages/sandbox/sandbox/src/index.ts)
+
+## `ctx.sandboxPolicy` — `SandboxPolicyService`
+
+The sandbox-policy service (`ctx.sandboxPolicy`). Owns the deployment default mode and workspace root; enforcing implementations read defaultMode and workspaceRoot, and the tool layers fold each session's `sandbox/mode` override with effectiveSandboxMode on top.
+
+Source: [`packages/sandbox/sandbox-policy/src/index.ts:60`](../../packages/sandbox/sandbox-policy/src/index.ts)
 
 ## `ctx.sessionPersistence` — `SessionPersistence` (abstract seam)
 

docs/core-data-structures/filesystem.md

@@ -132,6 +132,7 @@ type FsErrorCode =
   | 'FS_NOT_TEXT'
   | 'FS_NOT_REGULAR_FILE'
   | 'FS_PERMISSION_DENIED'
+  | 'FS_SANDBOX_DENIED'
   | 'FS_IO_ERROR'
   | 'FS_STALE_VERSION'
   | 'FS_NOT_OBSERVED'
@@ -140,7 +141,7 @@ type FsErrorCode =
   | 'FS_ABORTED'
 ```
 
-`FS_NOT_DIRECTORY`, `FS_PERMISSION_DENIED`, and `FS_IO_ERROR` are used by directory listing to distinguish an existing non-directory target, a denied listing, and an unexpected backend I/O failure. `FS_NOT_OBSERVED` means the policy plugin has no prior-observation record for this owner (or a `createIfAbsent` hit an existing file). `FS_STALE_VERSION` means the backend version no longer matches the observed one (or an edit hit a missing target). Freshness authorization has no partial/full distinction, so there is no `FS_PARTIAL_OBSERVATION`.
+`FS_NOT_DIRECTORY`, `FS_PERMISSION_DENIED`, and `FS_IO_ERROR` are used by directory listing to distinguish an existing non-directory target, a denied listing, and an unexpected backend I/O failure. `FS_SANDBOX_DENIED` is a POLICY refusal from a sandbox-enforcing backend (`dsh-fs-sandbox`) — the mode fence denied a write/edit — distinct from `FS_PERMISSION_DENIED` (the host kernel refusing). `FS_NOT_OBSERVED` means the policy plugin has no prior-observation record for this owner (or a `createIfAbsent` hit an existing file). `FS_STALE_VERSION` means the backend version no longer matches the observed one (or an edit hit a missing target). Freshness authorization has no partial/full distinction, so there is no `FS_PARTIAL_OBSERVATION`.
 
 ## The service and the plugin
 

docs/event-producer-consumer.md

@@ -21,9 +21,9 @@ This matrix shows which packages dispatch each harness-owned event and which pac
 | `agent/turn-continuation` | `waterfall` | [`packages/core/agent/src/types.ts:570`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) |
 | `agent/turn-stop` | `serial` | [`packages/core/agent/src/types.ts:588`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`serial`) | [`subagent-inprocess`](../packages/subagent/subagent-inprocess) |
 | `approval/request` | `waterfall` | [`packages/ui/user-approval/src/index.ts:70`](../packages/ui/user-approval/src/index.ts) | [`user-approval`](../packages/ui/user-approval) (`waterfall`) | [`acp`](../packages/ui/acp) |
-| `fs/edit-intent` | `waterfall` | [`packages/fs/fs/src/index.ts:123`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`waterfall`) | [`fs-policy`](../packages/fs/fs-policy) |
-| `fs/observed` | `emit` | [`packages/fs/fs/src/index.ts:138`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`emit`) | [`fs-policy`](../packages/fs/fs-policy) |
-| `fs/write-intent` | `waterfall` | [`packages/fs/fs/src/index.ts:109`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`waterfall`) | [`fs-policy`](../packages/fs/fs-policy) |
+| `fs/edit-intent` | `waterfall` | [`packages/fs/fs/src/index.ts:124`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`waterfall`) | [`fs-policy`](../packages/fs/fs-policy) |
+| `fs/observed` | `emit` | [`packages/fs/fs/src/index.ts:139`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`emit`) | [`fs-policy`](../packages/fs/fs-policy) |
+| `fs/write-intent` | `waterfall` | [`packages/fs/fs/src/index.ts:110`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`waterfall`) | [`fs-policy`](../packages/fs/fs-policy) |
 | `llm/stream` | `waterfall` | [`packages/llm/llm/src/index.ts:39`](../packages/llm/llm/src/index.ts) | [`llm`](../packages/llm/llm) (`waterfall`) | [`invariants`](../packages/support/invariants), [`llm-replay`](../packages/support/llm-replay) |
 | `session/created` | `emit` | [`packages/core/session/src/index.ts:52`](../packages/core/session/src/index.ts) | [`session`](../packages/core/session) (`events.dispatch`) | [`invariants`](../packages/support/invariants), [`jsonrpc`](../packages/ui/jsonrpc), [`session-persistence`](../packages/session-persistence/session-persistence) |
 | `session/disposed` | `emit` | [`packages/core/session/src/index.ts:64`](../packages/core/session/src/index.ts) | [`session`](../packages/core/session) (`events.dispatch`) | - |

docs/module-graph.md

@@ -35,6 +35,7 @@ flowchart TD
     pkg_fs["fs"]
     pkg_fs_local["fs-local"]
     pkg_fs_policy["fs-policy"]
+    pkg_fs_sandbox["fs-sandbox"]
     pkg_tool_fs["tool-fs"]
   end
   subgraph group_skill["packages/skill"]
@@ -113,6 +114,7 @@ flowchart TD
   subgraph group_sandbox["packages/sandbox"]
     pkg_sandbox["sandbox"]
     pkg_sandbox_local["sandbox-local"]
+    pkg_sandbox_policy["sandbox-policy"]
   end
   subgraph group_workflow["packages/workflow"]
     pkg_tool_workflow["tool-workflow"]
@@ -128,8 +130,6 @@ flowchart TD
   pkg_session --> pkg_scope
   pkg_system_prompt --> pkg_llm
   pkg_system_prompt --> pkg_scope
-  pkg_fs --> pkg_brand
-  pkg_fs --> pkg_llm
   pkg_web --> pkg_llm
   pkg_sandbox --> pkg_llm
   pkg_agent --> pkg_brand
@@ -139,11 +139,9 @@ flowchart TD
   pkg_agent --> pkg_system_prompt
   pkg_bash --> pkg_brand
   pkg_bash --> pkg_sandbox
-  pkg_bash --> pkg_session
-  pkg_fs_local --> pkg_fs
-  pkg_fs_policy --> pkg_fs
-  pkg_skill_local --> pkg_fs
-  pkg_skill_local --> pkg_skill
+  pkg_fs --> pkg_brand
+  pkg_fs --> pkg_llm
+  pkg_fs --> pkg_sandbox
   pkg_compact --> pkg_llm
   pkg_compact --> pkg_session
   pkg_web_fetch_local --> pkg_timeout
@@ -156,8 +154,14 @@ flowchart TD
   pkg_llm_replay --> pkg_session
   pkg_sandbox_local --> pkg_llm
   pkg_sandbox_local --> pkg_sandbox
+  pkg_sandbox_policy --> pkg_sandbox
+  pkg_sandbox_policy --> pkg_session
   pkg_bash_local --> pkg_bash
   pkg_bash_local --> pkg_timeout
+  pkg_fs_local --> pkg_fs
+  pkg_fs_policy --> pkg_fs
+  pkg_skill_local --> pkg_fs
+  pkg_skill_local --> pkg_skill
   pkg_compact_basic --> pkg_agent
   pkg_compact_basic --> pkg_compact
   pkg_compact_basic --> pkg_llm
@@ -196,8 +200,14 @@ flowchart TD
   pkg_bash_sandbox --> pkg_bash
   pkg_bash_sandbox --> pkg_bash_local
   pkg_bash_sandbox --> pkg_sandbox
+  pkg_bash_sandbox --> pkg_sandbox_policy
+  pkg_fs_sandbox --> pkg_fs
+  pkg_fs_sandbox --> pkg_fs_local
+  pkg_fs_sandbox --> pkg_sandbox
+  pkg_fs_sandbox --> pkg_sandbox_policy
   pkg_permission --> pkg_bash
   pkg_permission --> pkg_sandbox
+  pkg_permission --> pkg_sandbox_policy
   pkg_permission --> pkg_session
   pkg_permission --> pkg_user_approval
   pkg_agent_loop --> pkg_agent
@@ -209,16 +219,19 @@ flowchart TD
   pkg_agent_loop --> pkg_tools
   pkg_tool_bash --> pkg_agent
   pkg_tool_bash --> pkg_bash
-  pkg_tool_bash --> pkg_llm
   pkg_tool_bash --> pkg_sandbox
+  pkg_tool_bash --> pkg_sandbox_policy
   pkg_tool_bash --> pkg_system_prompt
   pkg_tool_bash --> pkg_tools
   pkg_tool_bash --> pkg_user_approval
   pkg_tool_fs --> pkg_fs
   pkg_tool_fs --> pkg_llm
+  pkg_tool_fs --> pkg_sandbox
+  pkg_tool_fs --> pkg_sandbox_policy
   pkg_tool_fs --> pkg_session
   pkg_tool_fs --> pkg_system_prompt
   pkg_tool_fs --> pkg_tools
+  pkg_tool_fs --> pkg_user_approval
   pkg_tool_skill --> pkg_agent
   pkg_tool_skill --> pkg_llm
   pkg_tool_skill --> pkg_skill
@@ -350,14 +363,11 @@ flowchart TD
 | [`llm-pi-ai`](../packages/llm/llm-pi-ai) | `llm` | [`llm`](../packages/llm/llm) |
 | [`session`](../packages/core/session) | `core` | [`brand`](../packages/util/brand), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope) |
 | [`system-prompt`](../packages/core/system-prompt) | `core` | [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope) |
-| [`fs`](../packages/fs/fs) | `fs` | [`brand`](../packages/util/brand), [`llm`](../packages/llm/llm) |
 | [`web`](../packages/web/web) | `web` | [`llm`](../packages/llm/llm) |
 | [`sandbox`](../packages/sandbox/sandbox) | `sandbox` | [`llm`](../packages/llm/llm) |
 | [`agent`](../packages/core/agent) | `core` | [`brand`](../packages/util/brand), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope), [`session`](../packages/core/session), [`system-prompt`](../packages/core/system-prompt) |
-| [`bash`](../packages/bash/bash) | `bash` | [`brand`](../packages/util/brand), [`sandbox`](../packages/sandbox/sandbox), [`session`](../packages/core/session) |
-| [`fs-local`](../packages/fs/fs-local) | `fs` | [`fs`](../packages/fs/fs) |
-| [`fs-policy`](../packages/fs/fs-policy) | `fs` | [`fs`](../packages/fs/fs) |
-| [`skill-local`](../packages/skill/skill-local) | `skill` | [`fs`](../packages/fs/fs), [`skill`](../packages/skill/skill) |
+| [`bash`](../packages/bash/bash) | `bash` | [`brand`](../packages/util/brand), [`sandbox`](../packages/sandbox/sandbox) |
+| [`fs`](../packages/fs/fs) | `fs` | [`brand`](../packages/util/brand), [`llm`](../packages/llm/llm), [`sandbox`](../packages/sandbox/sandbox) |
 | [`compact`](../packages/compact/compact) | `compact` | [`llm`](../packages/llm/llm), [`session`](../packages/core/session) |
 | [`web-fetch-local`](../packages/web/web-fetch-local) | `web` | [`timeout`](../packages/util/timeout), [`web`](../packages/web/web) |
 | [`web-search-deepseek`](../packages/web/web-search-deepseek) | `web` | [`web`](../packages/web/web) |
@@ -366,7 +376,11 @@ flowchart TD
 | [`session-persistence`](../packages/session-persistence/session-persistence) | `session-persistence` | [`session`](../packages/core/session) |
 | [`llm-replay`](../packages/support/llm-replay) | `support` | [`llm`](../packages/llm/llm), [`session`](../packages/core/session) |
 | [`sandbox-local`](../packages/sandbox/sandbox-local) | `sandbox` | [`llm`](../packages/llm/llm), [`sandbox`](../packages/sandbox/sandbox) |
+| [`sandbox-policy`](../packages/sandbox/sandbox-policy) | `sandbox` | [`sandbox`](../packages/sandbox/sandbox), [`session`](../packages/core/session) |
 | [`bash-local`](../packages/bash/bash-local) | `bash` | [`bash`](../packages/bash/bash), [`timeout`](../packages/util/timeout) |
+| [`fs-local`](../packages/fs/fs-local) | `fs` | [`fs`](../packages/fs/fs) |
+| [`fs-policy`](../packages/fs/fs-policy) | `fs` | [`fs`](../packages/fs/fs) |
+| [`skill-local`](../packages/skill/skill-local) | `skill` | [`fs`](../packages/fs/fs), [`skill`](../packages/skill/skill) |
 | [`compact-basic`](../packages/compact/compact-basic) | `compact` | [`agent`](../packages/core/agent), [`compact`](../packages/compact/compact), [`llm`](../packages/llm/llm), [`session`](../packages/core/session) |
 | [`hook-protocol`](../packages/hooks/hook-protocol) | `hooks` | [`bash`](../packages/bash/bash), [`session`](../packages/core/session) |
 | [`session-persistence-jsonl`](../packages/session-persistence/session-persistence-jsonl) | `session-persistence` | [`session`](../packages/core/session), [`session-persistence`](../packages/session-persistence/session-persistence) |
@@ -377,11 +391,12 @@ flowchart TD
 | [`user-interaction`](../packages/ui/user-interaction) | `ui` | [`agent`](../packages/core/agent), [`llm`](../packages/llm/llm) |
 | [`workflow`](../packages/workflow/workflow) | `workflow` | [`agent`](../packages/core/agent), [`brand`](../packages/util/brand), [`llm`](../packages/llm/llm) |
 | [`tools`](../packages/core/tools) | `core` | [`agent`](../packages/core/agent), [`code-runtime`](../packages/code-runtime/code-runtime), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope), [`session`](../packages/core/session), [`system-prompt`](../packages/core/system-prompt), [`user-approval`](../packages/ui/user-approval) |
-| [`bash-sandbox`](../packages/bash/bash-sandbox) | `bash` | [`bash`](../packages/bash/bash), [`bash-local`](../packages/bash/bash-local), [`sandbox`](../packages/sandbox/sandbox) |
-| [`permission`](../packages/ui/permission) | `ui` | [`bash`](../packages/bash/bash), [`sandbox`](../packages/sandbox/sandbox), [`session`](../packages/core/session), [`user-approval`](../packages/ui/user-approval) |
+| [`bash-sandbox`](../packages/bash/bash-sandbox) | `bash` | [`bash`](../packages/bash/bash), [`bash-local`](../packages/bash/bash-local), [`sandbox`](../packages/sandbox/sandbox), [`sandbox-policy`](../packages/sandbox/sandbox-policy) |
+| [`fs-sandbox`](../packages/fs/fs-sandbox) | `fs` | [`fs`](../packages/fs/fs), [`fs-local`](../packages/fs/fs-local), [`sandbox`](../packages/sandbox/sandbox), [`sandbox-policy`](../packages/sandbox/sandbox-policy) |
+| [`permission`](../packages/ui/permission) | `ui` | [`bash`](../packages/bash/bash), [`sandbox`](../packages/sandbox/sandbox), [`sandbox-policy`](../packages/sandbox/sandbox-policy), [`session`](../packages/core/session), [`user-approval`](../packages/ui/user-approval) |
 | [`agent-loop`](../packages/core/agent-loop) | `core` | [`agent`](../packages/core/agent), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope), [`session`](../packages/core/session), [`session-persistence`](../packages/session-persistence/session-persistence), [`system-prompt`](../packages/core/system-prompt), [`tools`](../packages/core/tools) |
-| [`tool-bash`](../packages/bash/tool-bash) | `bash` | [`agent`](../packages/core/agent), [`bash`](../packages/bash/bash), [`llm`](../packages/llm/llm), [`sandbox`](../packages/sandbox/sandbox), [`system-prompt`](../packages/core/system-prompt), [`tools`](../packages/core/tools), [`user-approval`](../packages/ui/user-approval) |
-| [`tool-fs`](../packages/fs/tool-fs) | `fs` | [`fs`](../packages/fs/fs), [`llm`](../packages/llm/llm), [`session`](../packages/core/session), [`system-prompt`](../packages/core/system-prompt), [`tools`](../packages/core/tools) |
+| [`tool-bash`](../packages/bash/tool-bash) | `bash` | [`agent`](../packages/core/agent), [`bash`](../packages/bash/bash), [`sandbox`](../packages/sandbox/sandbox), [`sandbox-policy`](../packages/sandbox/sandbox-policy), [`system-prompt`](../packages/core/system-prompt), [`tools`](../packages/core/tools), [`user-approval`](../packages/ui/user-approval) |
+| [`tool-fs`](../packages/fs/tool-fs) | `fs` | [`fs`](../packages/fs/fs), [`llm`](../packages/llm/llm), [`sandbox`](../packages/sandbox/sandbox), [`sandbox-policy`](../packages/sandbox/sandbox-policy), [`session`](../packages/core/session), [`system-prompt`](../packages/core/system-prompt), [`tools`](../packages/core/tools), [`user-approval`](../packages/ui/user-approval) |
 | [`tool-skill`](../packages/skill/tool-skill) | `skill` | [`agent`](../packages/core/agent), [`llm`](../packages/llm/llm), [`skill`](../packages/skill/skill), [`tools`](../packages/core/tools) |
 | [`subagent`](../packages/subagent/subagent) | `subagent` | [`agent`](../packages/core/agent), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope), [`tools`](../packages/core/tools) |
 | [`tool-web`](../packages/web/tool-web) | `web` | [`llm`](../packages/llm/llm), [`system-prompt`](../packages/core/system-prompt), [`tools`](../packages/core/tools), [`web`](../packages/web/web) |

docs/persistence-catalog.md

@@ -71,18 +71,6 @@ Types: [ContentBlock](core-data-structures/core.md) · [TokenUsage](core-data-st
 
 Source: [`packages/core/session/src/types.ts:329`](../packages/core/session/src/types.ts)
 
-### `bash/*`
-
-#### `bash/sandbox-mode` — log-only
-
-The session's sandbox mode was switched — log-only (like `approval/*`; NOT a surface event, carries no `surfaceOp`): durable and replayable, never in the model transcript. The LAST such event is the session's override (effectiveSandboxMode); who asked for it is derivable from position (an event after the log's last `request/header*` was a runtime switch by the user; see the tool layer's narrator).
-
-```ts persistence-catalog
-'bash/sandbox-mode': { mode: SandboxMode }
-```
-
-Source: [`packages/bash/bash/src/session-mode.ts:31`](../packages/bash/bash/src/session-mode.ts)
-
 ### `compact/*`
 
 #### `compact/end` — log-only
@@ -157,13 +145,13 @@ Source: [`packages/hooks/hook-protocol/src/types.ts:45`](../packages/hooks/hook-
 
 #### `permission/preset` — log-only
 
-The session's permission preset was switched — log-only (the `bash/sandbox-mode` precedent): durable and replayable, never in the model transcript. The LAST such event is the session's preset (effectivePermissionPreset); the knob events the switch wrote through follow it in the same turn, and they — not this record of the user's choice — are what execution reads.
+The session's permission preset was switched — log-only (the `sandbox/mode` precedent): durable and replayable, never in the model transcript. The LAST such event is the session's preset (effectivePermissionPreset); the knob events the switch wrote through follow it in the same turn, and they — not this record of the user's choice — are what execution reads.
 
 ```ts persistence-catalog
 'permission/preset': { preset: string }
 ```
 
-Source: [`packages/ui/permission/src/index.ts:42`](../packages/ui/permission/src/index.ts)
+Source: [`packages/ui/permission/src/index.ts:45`](../packages/ui/permission/src/index.ts)
 
 ### `prompt/*`
 
@@ -201,6 +189,18 @@ Amendment to the folded EpochHeader: at least one of a SystemDelta, a ToolsDelta
 
 Source: [`packages/core/session/src/types.ts:391`](../packages/core/session/src/types.ts)
 
+### `sandbox/*`
+
+#### `sandbox/mode` — log-only
+
+The session's sandbox mode was switched — log-only (like `approval/*`; NOT a surface event, carries no `surfaceOp`): durable and replayable, never in the model transcript. The LAST such event is the session's override (effectiveSandboxMode); who asked for it is derivable from position (an event after the log's last `request/header*` was a runtime switch by the user; see the tool layer's narrator).
+
+```ts persistence-catalog
+'sandbox/mode': { mode: SandboxMode }
+```
+
+Source: [`packages/sandbox/sandbox-policy/src/session-mode.ts:34`](../packages/sandbox/sandbox-policy/src/session-mode.ts)
+
 ### `steering/*`
 
 #### `steering/message` — surface

docs/rfc/INDEX.md

@@ -78,6 +78,7 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
 | [The self-referential cordis toolset](implemented/feature/2026-07-08-self-referential-cordis-toolset.md) | 2026-07-08 |
 | [Exact session query service](implemented/feature/2026-07-10-session-query-service.md) | 2026-07-10 |
 | [Configure subagent persona, tool visibility, and depth](implemented/feature/2026-07-12-subagent-persona-tool-filter-and-depth.md) | 2026-07-12 |
+| [Cross-family file sandbox — one policy home, a sandboxed fs provider, and fs escalation parity](implemented/feature/2026-07-14-cross-family-fs-sandbox.md) | 2026-07-14 |
 
 ### Simplification
 

docs/rfc/implemented/feature/2026-07-06-sandbox.md

@@ -115,7 +115,7 @@ The default is composition config (`cordis.yml`) — operator-owned, process-wid
 
 ```ts
 interface SessionEventMap {
-  'bash/sandbox-mode': { mode: 'read-only' | 'workspace-write' | 'danger-full-access' }
+  'sandbox/mode': { mode: 'read-only' | 'workspace-write' | 'danger-full-access' }
   'approval/policy': { policy: 'ask' | 'never' }
 }
 ```
@@ -130,9 +130,7 @@ Each owner exports the same three-piece kit: the event declaration, a pure fold
 
 #### In-process tools
 
-fs/web/todo execute in-process, so their sandbox semantics are policy at their seams: the fs intent gates deciding by the shared mode vocabulary (§ Deferred phases, cross-family) make `read-only` a real boundary instead of a bash-only approximation — until then the contract says so honestly. No generic per-tool sandbox runtime: a host-mediated tool leaves the process only by returning declarative effects the host validates, which is a rewrite, not a wrapper.
-
-FIXME: Revisit this tool-local boundary. The follow-up design needs to determine whether sandboxing becomes a global harness capability that applies uniformly to every tool, instead of expressing in-process enforcement independently at each tool seam.
+fs/web/todo execute in-process, so their sandbox semantics are policy at their seams. The fs seam now enforces the shared mode vocabulary through a sandboxed provider (`dsh-fs-sandbox` fences write/edit by mode; see [the cross-family fs sandbox RFC](2026-07-14-cross-family-fs-sandbox.md)), so `read-only`/`workspace-write` are real boundaries for the filesystem tools, not a bash-only approximation. web/todo remain unfenced (web's only effect is network, outside the file-effect mode vocabulary). No generic per-tool sandbox runtime: a host-mediated tool leaves the process only by returning declarative effects the host validates, which is a rewrite, not a wrapper — the follow-up settled on one shared policy home (`ctx.sandboxPolicy`) with per-seam enforcement, not a uniform wrapper.
 
 ### Testing
 
@@ -145,8 +143,7 @@ FIXME: Revisit this tool-local boundary. The follow-up design needs to determine
 
 Each phase gets its full design when picked up, validated against the code at that time, and lands with unit, real-API e2e, and snapshot coverage at the tiers it touches.
 
-- **Per-session workspace root** — the executor's write boundary stays config-fixed for its lifetime while each ACP session has its own cwd; a per-session root rides the same per-call policy carrier once designed.
-- **Cross-family boundary** — the fs intent gates decide by the shared mode, making `read-only`/`workspace-write` real boundaries beyond bash.
+- **Per-session workspace root** — the executor's write boundary stays config-fixed for its lifetime while each ACP session has its own cwd; a per-session root rides the same per-call policy carrier once designed. Centralizing the root on `ctx.sandboxPolicy` (the [cross-family fs sandbox RFC](2026-07-14-cross-family-fs-sandbox.md)) is the groundwork.
 - **Second consumer** — `subagent-acp` optionally confines child agents (per-call policy; unconfined default — a child agent must write its own persistence).
 - **More environments** — an environment-coherent capability group example (e.g. bash+fs against one container).
 - **Windows chain** — `PLATFORM_CHAINS.win32` is reserved and empty (fail-closed); filling it means a confinement runner from the AppContainer/restricted-token family, shipped from its own repository on the `node-addon-landlock-run` template, plus its profile dialect and denial/runner-failure signatures.
@@ -190,7 +187,7 @@ What shipped pins — the tiers in Testing hold each:
 Costs and accepted limits:
 
 - **The one-wrapper illusion is given up knowingly.** A `tools/pre-execute` wrapper plus prompt conventions does not solve sandbox approval — the correct design costs structured denials, native runner probes, per-call policy carriage, and consistent cross-family enforcement, and this design pays it.
-- **`read-only` is not yet a cross-family boundary.** Until the fs intent gates decide by the shared mode, the claim holds for bash only; the contract says so honestly (§ In-process tools).
+- **`read-only` became a cross-family boundary through a follow-up.** This RFC shipped bash-only enforcement; the [cross-family fs sandbox RFC](2026-07-14-cross-family-fs-sandbox.md) extends the same mode vocabulary to the filesystem tools through a sandboxed `ctx.fs` provider and relocates the mode/root config and the `sandbox/mode` override to `ctx.sandboxPolicy` (§ In-process tools).
 - **Windows has no backend.** Its chain slot is reserved empty — fail-closed, never a fallthrough; filling it is a deferred phase.
 - **The Seatbelt rung leans on Apple's deprecated-but-shipped `sandbox-exec` CLI.** As darwin's sole candidate it is selected without probing, so a future removal surfaces at execution as the runner-failure classification — re-thrown `SANDBOX_UNAVAILABLE`, the command never runs; fail closed, never open.
 - **Landlock confinement is only as complete as the running kernel's ABI.** Reported as `enforcement: 'partial'` rather than refused — the deliberate trade that keeps the fallback available on older-kernel hosts.
@@ -212,7 +209,7 @@ Behavioral and usage questions only — every "why not X?" design question lives
 - **What happens on a platform with no backend — Windows today?** `confine()` throws the fail-closed `SANDBOX_UNAVAILABLE` and the command never spawns; `win32` is a reserved EMPTY chain, pinned by test to fail closed identically until a Windows runner fills it (§ Deferred phases).
 - **`bwrap` is installed on my host but unusable (disabled unprivileged userns, an LSM denying `mount`) — what happens?** The chain probe is functional — it builds and enforces a real profile rather than checking `--version` — so a present-but-unusable `bwrap` fails its probe, selection falls to the registry-installed Landlock launcher, and the verdict is cached for the provider's lifetime.
 - **Does the sandbox restrict network or process visibility?** No — `SandboxMode` claims FILE effects only; the bwrap profile deliberately does not unshare pid, and no backend claims network. Whether network restriction becomes its own knob is left open in § The seam.
-- **Which tools actually run confined?** OS subprocesses through `ctx.bash` — the bash tools, and hook commands transitively. fs/web/todo execute in-process, where an `execve` wrapper is mechanically meaningless; their `read-only` semantics arrive with the cross-family deferred phase, and until then the contract says bash-only honestly.
+- **Which tools actually run confined?** OS subprocesses through `ctx.bash` — the bash tools, and hook commands transitively — plus the filesystem tools (`read`/`write`/`edit`) through the sandboxed `ctx.fs` provider (the [cross-family fs sandbox RFC](2026-07-14-cross-family-fs-sandbox.md)): bash confines via the OS runner, fs via an in-process path fence, both keying off the same `ctx.sandboxPolicy` mode. web/todo stay in-process and unfenced (web's only effect is network, outside the file-effect mode vocabulary).
 - **Does a granted escalation persist, or cover background tasks?** Neither: the grant is consumed by the very call that asked (foreground or background), that one call reports the mode it actually ran under, and every neighbor keeps its own. How escalation should be DEFINED for a background denial that only surfaces later via `bash_output` is left open in § Escalation.
 - **When does an editor's mode switch take effect?** Mid-turn: appended immediately, honored by the very next call's stamp. Idle: held on the bridge's session record, anchored at the next turn's `agent/prompt-submit`, with N flips coalescing to at most one event (none if net-zero); a crash before anchoring reverts it and `session/load` reports the truth. The model is not told — its next command simply behaves under the new mode.
 - **What survives a restart — and what if the operator changed the config default while the process was down?** Overrides replay from the session log (`effective = fold ?? config`), so a resumed session keeps its modes with zero catch-up machinery; a default that drifted offline changes behavior the same way a switch does (the approval policy, being stated, is additionally narrated with operator/config attribution).

docs/rfc/implemented/feature/2026-07-14-cross-family-fs-sandbox.md

@@ -0,0 +1,92 @@
+# RFC: Cross-family file sandbox — one policy home, a sandboxed fs provider, and fs escalation parity
+
+Status: implemented
+
+## Problem
+
+`SandboxMode` claims file effects, but originally only `ctx.bash` enforced it. The fs tools (`write`/`edit`) mutate the host filesystem in-process through `ctx.fs`, where an OS argv wrapper is mechanically meaningless — [the sandbox RFC](2026-07-06-sandbox.md) § In-process tools records this and left cross-family enforcement as a deferred phase with an open question: whether in-process enforcement stays per-seam or becomes a uniform harness capability. This RFC is that phase, and answers it: one shared policy home, per-seam enforcement at each family's correct altitude.
+
+The gap was not read-only-shaped. A confined coding agent's product mode is `workspace-write`: bash may already write under the workspace root while everything outside is denied, so an fs enforcement that could only deny-all would be strictly worse than disabling the fs tools — the model would attempt an in-workspace `write`, be denied, and learn to detour through `bash` heredocs. Cross-family enforcement therefore speaks the full mode ladder, including the path-containment judgment `workspace-write` requires (canonical targets; `..`/symlink/absolute-path escapes) and the same escalation lever bash carries.
+
+A second enforcing family also exposed an ownership problem in the original layout. The deployment default (`mode` + `workspaceRoot`) was configured on `dsh-bash-sandbox`, and the per-session override event was `bash/sandbox-mode`, folded and written by `dsh-bash`'s session-mode kit. With fs enforcing the same policy, either fs reads bash's config and events (a capability family depending on a sibling's plugin config) or each family carries its own copy — and two copies of `workspaceRoot` drift into exactly the split world the sandbox RFC warns about: bash confined to one root while fs fences another.
+
+## Decision
+
+Three coordinated pieces, all composed from the leaf `cordis.yml`, none touching `agent-loop`.
+
+### `ctx.sandboxPolicy` — one home for mode and workspace root
+
+`packages/sandbox/sandbox-policy/` (`@deepseek-ai/dsh-sandbox-policy`) registers `ctx.sandboxPolicy`, the single owner of the deployment's sandbox policy:
+
+- `Config`: `mode` (the closed `SandboxMode` union, default `read-only`) and `workspaceRoot` (default the process cwd, resolved absolute). Misconfiguration fails loud at load.
+- The per-session override event `sandbox/mode`, with its pure fold (`effectiveSandboxMode(events)`), its write path (`setSandboxMode(session, mode)`), and `SANDBOX_MODES`. The event is policy state — consumed by two families — so it lives here, not in either capability's seam. Its shape and log-only semantics match the `approval/*` precedent.
+- `defaultMode` / `workspaceRoot` accessors the enforcing implementations read for their resolve fallback and boundary.
+
+`dsh-bash-sandbox` carries no sandbox config of its own — it injects `sandboxPolicy` and reads the default from it; its `resolve()` precedence is unchanged (escalation grant > per-call stamp > default). `dsh-tool-bash` and `dsh-tool-fs` fold the session's `sandbox/mode` with `effectiveSandboxMode` to stamp each call; `dsh-permission` presets and the ACP bridge write through the relocated setter. The seam that owns bash execution no longer depends on `dsh-session` at all — the session dependency moved to the policy package with the fold.
+
+### `dsh-fs-sandbox` — enforcement inside the provider
+
+`packages/fs/fs-sandbox/` (`@deepseek-ai/dsh-fs-sandbox`) mirrors the `bash-local`/`bash-sandbox` split: `SandboxedFileSystem extends LocalFileSystem`, registered as `ctx.fs`, injecting `sandboxPolicy`. Reads (`resolve`/`stat`/`readText`/`streamText`/`listDir`) pass through untouched — every mode permits reading. The two mutations enforce by mode before delegating to the inherited atomic write:
+
+- `read-only` denies `writeText`/`editText` outright.
+- `workspace-write` fences the canonicalized target against the writable-root set — `writableRoots(policy)` in `dsh-sandbox`: the workspace root plus the platform temp areas (`/tmp`, `os.tmpdir()`), each realpathed — the SAME set the Seatbelt profile grants, so the fs fence is the fourth dialect of one mode meaning alongside the bwrap/Landlock/Seatbelt profiles, and "the write tool cannot write `/tmp` but bash can" asymmetries cannot arise. Containment is prefix-inclusion on real paths; the target is re-canonicalized (`resolve` realpaths the deepest existing ancestor) immediately before delegating, so an ancestor symlink swapped since the tool resolved it is caught.
+- `danger-full-access` delegates unfenced.
+
+A denial is the structured `FS_SANDBOX_DENIED` carrying the effective mode — distinct from `FS_PERMISSION_DENIED` (a host EACCES is the world refusing; this is policy refusing). No text inference: an in-process fence knows exactly what it denied. The per-call carrier is a trailing optional `sandboxMode` on `writeText`/`editText` (the filesystem twin of `BashExecRequest.sandboxMode`); the seam stays session-free (the caller stamps, exactly as `resolve` takes a cwd), and the bare local backend carries-and-ignores it. `FileSystem.sandboxMode` is the capability fact (`undefined` on the base and `fs-local`, the default on `SandboxedFileSystem`), so the tool layer advertises escalation from composition truth.
+
+The threat model is stated in the package README: a policy fence in trusted code over model-controlled paths, not a kernel boundary — the operations are the seam's own, only the target path is untrusted, so canonicalize-then-contain is the complete answer to this surface (the `code-runtime` "containment, not a security boundary" precedent). Kernel-grade isolation of untrusted CODE stays `ctx.bash`'s job. The residual resolve-to-syscall race is narrowed by the in-place re-canonicalization and eliminated only by platform primitives (`openat2` `RESOLVE_BENEATH`) not worth their portability cost here.
+
+### Tool parity — one denial marker, one escalation flow
+
+`dsh-tool-fs` stamps the effective mode onto each mutation and maps `FS_SANDBOX_DENIED` to the marker the model already knows from bash: `[sandbox: file access denied under <mode> mode]`. When `ctx.fs.sandboxMode` reports a confining mode at registration, `write` and `edit` advertise the same `sandbox_permissions` + `justification` fields, teach the same same-turn retry, and resolve the same `ctx.approval` request before executing — the four outcomes and their verbatim fail-closed texts carried over from [the sandbox RFC](2026-07-06-sandbox.md) § Escalation (strict widening checked at execution against the call's effective mode; a grant consumed by the one call that asked; no new session events).
+
+The shared pieces live in `dsh-sandbox`, which owns the mode types: `WIDER_MODES`, the escalation-target enum, the argument-pairing validation, the denial/hint marker builders, and `approveEscalation` — the ordered fail-closed choreography. `approveEscalation` takes a minimal STRUCTURAL ask-function (`EscalationChannel`), not the approval service type, so `dsh-sandbox` gains no dependency on the approval or agent packages: each tool closes over its own `ctx.approval.request(...)`, agent, call id, and tool name and hands the closure down. `dsh-tool-bash` and `dsh-tool-fs` both use these; the cross-file duplication gate holds the single-sourcing honest.
+
+The [`examples/acp-agent`](../../../../examples/acp-agent/cordis.yml) composition loads `dsh-sandbox-policy` and `dsh-fs-sandbox`, moves the `mode`/`workspaceRoot` config to the policy entry, and drops the old gating that disabled the fs stack under confined modes; `fs-policy` (read-before-edit) composes orthogonally on top. The system prompt still states no sandbox mode — the marker teaches the boundary at the moment it matters, per the sandbox RFC's live evidence.
+
+### The enforcement point: provider, not intent gate
+
+The sandbox RFC's original cross-family sketch put fs enforcement on the `fs/write-intent`/`fs/edit-intent` events. This RFC enforces in the provider instead, on two mechanical facts: the intent slots are single-decision first-wins (occupied by `dsh-fs-policy`, whose contract names a second decider a misconfiguration), and the intent events are dispatched only by `dsh-tool-fs` — a direct `ctx.fs` caller (a cordis-mounted plugin, a custom tool) bypasses them, where provider-level enforcement covers every caller by construction. The sandbox RFC's deferred-phase wording is updated to match in the same change.
+
+### Out of scope
+
+- **Network policy for `ctx.web`** — `SandboxMode` claims file effects only; a web-only network knob while bash `curl` runs free would be a false boundary. Revisit when a bash backend enforces network (bwrap `--unshare-net`, Landlock ABI v4+).
+- **The `subagent-acp` consumer** and **per-session workspace root** — unchanged deferred phases of the sandbox RFC; centralizing the root in `ctx.sandboxPolicy` is groundwork for the latter, not its design.
+- **A uniform per-tool sandbox runtime** — remains rejected for the reasons in the sandbox RFC.
+
+## Alternatives considered
+
+- **Enforce on the `fs/*` intent events (the sandbox RFC's original sketch)** — rejected on the two mechanical facts in § The enforcement point: single-slot first-wins already occupied, and a bypass for direct `ctx.fs` callers. Provider-level enforcement covers every caller and mirrors bash's swap-the-implementation shape.
+- **Enforce in `tools/pre-execute`** — rejected: the listener sees the model's raw path string before `resolve()`, so it would re-implement cwd defaulting and symlink canonicalization and still race the real resolve. Disqualifying for `workspace-write`, a judgment over canonical paths.
+- **Inline checks in `dsh-tool-fs`** — rejected: covers only the tool path (same bypass as the intent events) and duplicates resolve knowledge one layer above where the canonical target already exists.
+- **A `mode` flag on `dsh-fs-local` instead of a sibling backend** — rejected: the capability fact must be composition truth the way `dsh-bash-local` vs `dsh-bash-sandbox` is; a config flag makes the tool's advertisement conditional on configuration, and the bash family already establishes the sibling-package shape.
+- **Kernel-enforced fs mutations via a confined helper subprocess** — rejected: a process per write; `editText`'s read-match-write critical section would have to move wholesale into the child to stay atomic; and the threat surface (trusted operations, untrusted path argument) does not need a kernel — the fence in trusted code is the complete answer, while untrusted-code isolation stays on `ctx.bash`.
+- **Per-family policy config with a load-time consistency check** — rejected: two homes for one fact, patched by a check that must enumerate every future enforcing family; the policy service makes drift inexpressible instead of detected.
+- **Keep the override event in `dsh-bash` as `bash/sandbox-mode`** — rejected: the event is policy state consumed by two families; leaving it bash-named forces `dsh-fs-sandbox` to depend on bash vocabulary. Pre-release, the rename is a same-change move with snapshot re-records, no shims.
+- **Escalation choreography imported from the approval/agent packages into `dsh-sandbox`** — rejected: it would invert the layering (a base vocabulary package depending on UI/agent packages). The structural ask-function keeps the logic single-sourced in `dsh-sandbox` while the dependencies stay in the tool layer that already holds them.
+- **A consolidated mutation-options object on the fs seam** (the shape first sketched for the per-call carrier) — rejected on friction: it churns every `writeText`/`editText` caller and splits `signal` across an options bag for mutations while reads keep it positional. A trailing optional `sandboxMode` matches bash's carry-and-ignore pattern and keeps `signal` symmetric across the seam.
+- **Extra writable-root grants on `SandboxPolicy` now** — deferred unchanged: `writableRoots()` derives from the mode meaning today; ad-hoc grants are an escalation-scope question the sandbox RFC left open.
+
+## Consequences
+
+What shipped — the tiers in § Testing hold each:
+
+- Under `read-only`, `write`/`edit` return the `[sandbox: file access denied under read-only mode]` marker and the disk is untouched; `read`/`listDir` behave identically to `dsh-fs-local`.
+- Under `workspace-write`, mutations land under the workspace root and the temp areas and are denied outside; the containment matrix — `..` traversal, absolute paths outside, a pre-existing symlinked directory inside pointing out, and a new file created under such a symlink — denies every escape on real disks.
+- A denied fs mutation retried once with `sandbox_permissions` + `justification` prompts through the composed approval chain; a grant runs exactly that call under the wider mode and the write lands; rejected/cancelled/unavailable each produce their verbatim fail-closed text and mutate nothing.
+- One `permission` preset switch governs both families: after a session switches modes, the next bash call and the next fs mutation both honor the new mode from the same `sandbox/mode` fold.
+- A direct `ctx.fs.writeText` with no per-call stamp is confined at the deployment default.
+- The escalation fields on `write`/`edit` exist exactly when the mounted `ctx.fs` confines, absent under `dsh-fs-local`.
+- `agent-loop` is untouched — everything rides `ctx.sandboxPolicy`, the `ctx.fs` seam, `SessionEventMap` merging, and the tool-execution pipeline.
+
+Costs and accepted limits:
+
+- **The fs fence is a policy boundary, not a kernel one.** Its threat surface is model-chosen paths, not adversarial host processes; the residual resolve-to-syscall TOCTOU is narrowed, not eliminated, and the README says so. Kernel boundaries remain bash's.
+- **`dsh-bash-sandbox` gains a hard dependency on `ctx.sandboxPolicy`.** Every sandboxed composition adds one `cordis.yml` entry or fails loud at load — the intended pre-release foundation move; the examples update in the same change.
+- **Fence-vs-runner parity is derived, not asserted.** The fs fence and the Seatbelt profile both take their writable set from `writableRoots`, and a parity unit test pins the sets; a runner profile changing its writable set without that function would drift.
+- **The marker and escalation teaching now serve two families.** A wording change is a coordinated edit behind one builder in `dsh-sandbox`; the duplication gate and pinned snapshots hold it single-sourced, at the cost that fs and bash cannot deliberately diverge in phrasing without splitting the builder.
+
+## Testing
+
+- Unit: `dsh-sandbox` pins the escalation ladder, the marker builders, the argument-pairing validation, and `approveEscalation`'s ordered fail-closed sequence (non-widening, no-approval, no-agent, each outcome), plus `writableRoots`/`canonicalPath`. `dsh-sandbox-policy` pins the default accessors, the fold/setter, the load-time mode rejection, and HMR safety. `dsh-fs-sandbox` pins the per-mode fence and the containment matrix (inside, temp area, absolute-outside, `..`, symlinked-out directory, new file under one, path-equals-root, root-ending-in-separator) on a real filesystem, plus the per-call override and HMR safety. `dsh-tool-fs` pins advertisement gating, the mode stamp, the fold, denial-marker mapping, and the full escalation matrix (grant, reject, no-service, no-agent, pairing, non-confining guard). `dsh-tool-bash`, `dsh-bash-sandbox`, and `dsh-permission` migrate to the relocated policy/kit.
+- Snapshot: the acp-agent example composes `dsh-sandbox-policy` + `dsh-fs-sandbox`; the pinned header carries the fs escalation fields and the `sandbox/mode` event name, re-recorded once.

examples/acp-agent/composition.md

@@ -12,6 +12,8 @@ flowchart LR
   cfg --> plugin_acp_llm_deepseek
   plugin_acp_sandbox["sandbox<br/>@deepseek-ai/dsh-sandbox-local"]
   cfg --> plugin_acp_sandbox
+  plugin_acp_sandbox_policy["sandbox-policy<br/>@deepseek-ai/dsh-sandbox-policy"]
+  cfg --> plugin_acp_sandbox_policy
   plugin_acp_bash["bash<br/>@deepseek-ai/dsh-bash-sandbox"]
   cfg --> plugin_acp_bash
   plugin_acp_approval["approval<br/>@deepseek-ai/dsh-user-approval"]
@@ -45,8 +47,8 @@ flowchart LR
   cfg --> plugin_acp_tool_todo
   plugin_acp_repeat_tool_guard["repeat-tool-guard<br/>@deepseek-ai/dsh-repeat-tool-guard"]
   cfg --> plugin_acp_repeat_tool_guard
-  plugin_acp_fs_local["fs-local<br/>@deepseek-ai/dsh-fs-local"]
-  cfg --> plugin_acp_fs_local
+  plugin_acp_fs_sandbox["fs-sandbox<br/>@deepseek-ai/dsh-fs-sandbox"]
+  cfg --> plugin_acp_fs_sandbox
   plugin_acp_fs_policy["fs-policy<br/>@deepseek-ai/dsh-fs-policy"]
   cfg --> plugin_acp_fs_policy
   plugin_acp_tool_fs["tool-fs<br/>@deepseek-ai/dsh-tool-fs"]
@@ -61,6 +63,7 @@ flowchart LR
 | --- | --- |
 | `llm-deepseek` | `@deepseek-ai/dsh-llm-deepseek` |
 | `sandbox` | `@deepseek-ai/dsh-sandbox-local` |
+| `sandbox-policy` | `@deepseek-ai/dsh-sandbox-policy` |
 | `bash` | `@deepseek-ai/dsh-bash-sandbox` |
 | `approval` | `@deepseek-ai/dsh-user-approval` |
 | `permission` | `@deepseek-ai/dsh-permission` |
@@ -74,7 +77,7 @@ flowchart LR
 | `tool-workflow` | `@deepseek-ai/dsh-tool-workflow` |
 | `tool-todo` | `@deepseek-ai/dsh-tool-todo` |
 | `repeat-tool-guard` | `@deepseek-ai/dsh-repeat-tool-guard` |
-| `fs-local` | `@deepseek-ai/dsh-fs-local` |
+| `fs-sandbox` | `@deepseek-ai/dsh-fs-sandbox` |
 | `fs-policy` | `@deepseek-ai/dsh-fs-policy` |
 | `tool-fs` | `@deepseek-ai/dsh-tool-fs` |
 | `hooks-claude` | `@deepseek-ai/dsh-hooks-claude` |

examples/acp-agent/cordis.yml

@@ -23,19 +23,25 @@
       - deepseek-v4-flash
       - deepseek-v4-pro
 
-# The default composition confines bash to the workspace and asks before a
-# wider retry. Snapshot runs select danger-full-access so the established
-# scenarios remain runner-independent; DSH_PERMISSION_MODE provides the same
-# explicit deployment/test override outside the snapshot harness.
+# The default composition confines bash AND the filesystem tools to the
+# workspace and asks before a wider retry. Snapshot runs select
+# danger-full-access so the established scenarios remain runner-independent;
+# DSH_PERMISSION_MODE provides the same explicit deployment/test override
+# outside the snapshot harness. The sandbox mode + workspace root live on
+# ctx.sandboxPolicy — the one home both enforcing families (bash, fs) read.
 - id: sandbox
   name: '@deepseek-ai/dsh-sandbox-local'
 
+- id: sandbox-policy
+  name: '@deepseek-ai/dsh-sandbox-policy'
+  config:
+    mode: !!js "process.env.DSH_PERMISSION_MODE ?? (process.env.DSH_SNAPSHOT === undefined ? 'workspace-write' : 'danger-full-access')"
+    workspaceRoot: !!js process.cwd()
+
 - id: bash
   name: '@deepseek-ai/dsh-bash-sandbox'
   config:
     timeoutMs: 60000
-    mode: !!js "process.env.DSH_PERMISSION_MODE ?? (process.env.DSH_SNAPSHOT === undefined ? 'workspace-write' : 'danger-full-access')"
-    workspaceRoot: !!js process.cwd()
 
 - id: approval
   name: '@deepseek-ai/dsh-user-approval'
@@ -119,22 +125,21 @@
 - id: repeat-tool-guard
   name: '@deepseek-ai/dsh-repeat-tool-guard'
 
-# Filesystem tools do not ride the bash sandbox, so the confined default omits
-# them. Snapshot tests and explicit danger-full-access launches keep the
-# established filesystem scenarios by enabling the whole stack together.
-- id: fs-local
-  name: '@deepseek-ai/dsh-fs-local'
-  disabled: !!js "(process.env.DSH_PERMISSION_MODE ?? (process.env.DSH_SNAPSHOT === undefined ? 'workspace-write' : 'danger-full-access')) !== 'danger-full-access'"
+# The filesystem stack rides the SAME sandbox policy as bash: dsh-fs-sandbox
+# replaces dsh-fs-local behind ctx.fs and fences write/edit by the effective
+# mode (read-only denies, workspace-write contains to the workspace + temp
+# roots, danger-full-access passes through), so read/write/edit are available
+# under every mode. fs-policy (read-before-edit) composes orthogonally on top.
+- id: fs-sandbox
+  name: '@deepseek-ai/dsh-fs-sandbox'
   config:
     cwd: !!js process.cwd()
 
 - id: fs-policy
   name: '@deepseek-ai/dsh-fs-policy'
-  disabled: !!js "(process.env.DSH_PERMISSION_MODE ?? (process.env.DSH_SNAPSHOT === undefined ? 'workspace-write' : 'danger-full-access')) !== 'danger-full-access'"
 
 - id: tool-fs
   name: '@deepseek-ai/dsh-tool-fs'
-  disabled: !!js "(process.env.DSH_PERMISSION_MODE ?? (process.env.DSH_SNAPSHOT === undefined ? 'workspace-write' : 'danger-full-access')) !== 'danger-full-access'"
 
 # The Claude Code hook bridge. `configPath` is PROCESS-LEVEL: it is read ONCE at
 # load and the relative `./hooks.json` resolves against the ACP server's launch

examples/acp-agent/tests/snapshots/advanced-toolchain/system-prompt.golden.md

@@ -5,6 +5,12 @@ You are a coding assistant powered by the deepseek-v4-flash model. Your working
 Verify your work by running the code or tests. Keep answers brief and factual.
 
 
+Use the read tool — not shell commands like cat — to inspect text files. Results include line numbers. Use offset and limit to continue reading large files.
+
+Use the write tool to create files or completely replace file contents. Existing files are overwritten, so read an existing file first (the default fs-policy requires it) and prefer edit for targeted changes.
+
+Use the edit tool for targeted changes to existing UTF-8 text files. It replaces literal old_string with new_string; by default old_string must appear exactly once. If old_string appears multiple times, provide a more specific old_string or set replace_all to true. Read the file first (the default fs-policy requires it), unless you just created or edited it in this session.
+
 Check the [exit code: N] marker on every bash result; investigate failures before moving on.
 
 Approval prompts are disabled in this session: actions that require approval are rejected automatically — do not request sandbox escalation (do not set `sandbox_permissions`).
@@ -67,6 +73,30 @@ declare const tools: {
     /** The dynamic mount id returned by cordis_mount (e.g. "dyn-1"). */
     id: string;
   }): Promise<string>;
+  /** Edit an existing UTF-8 text file by replacing literal text. */
+  edit(args: {
+    /** Path to edit, resolved by the filesystem backend. */
+    file_path: string;
+    /** Literal text to replace. Must match exactly. */
+    old_string: string;
+    /** Literal replacement text. Use an empty string to delete the match. */
+    new_string: string;
+    /** Replace all matches. Defaults to false; when false, old_string must appear exactly once. */
+    replace_all?: boolean;
+    /** The wider sandbox mode this file operation needs. Only valid as a one-shot retry of an operation the sandbox just denied; requires justification and user approval. */
+    sandbox_permissions?: "workspace-write" | "danger-full-access";
+    /** Required with sandbox_permissions: one sentence for the user explaining why this exact file operation needs the wider access. */
+    justification?: string;
+  }): Promise<string>;
+  /** Read a UTF-8 text file and return line-numbered content. */
+  read(args: {
+    /** Path to read, resolved by the filesystem backend. */
+    file_path: string;
+    /** 1-based first line to return. Defaults to 1. */
+    offset?: number;
+    /** Maximum number of lines to return. Defaults to 2000. */
+    limit?: number;
+  }): Promise<string>;
   /** Load the full instructions for an available skill. Call this with the exact skill name from the session skill catalog before acting on a task that names or clearly matches that skill. */
   skill(args: {
     /** The exact skill name from the available skills list. */
@@ -121,5 +151,16 @@ declare const tools: {
     /** Optional JSON input exposed to the script as the `args` global (wrap a bare list as a field, e.g. {"files": [...]}). */
     args?: Record<string, unknown>;
   }): Promise<string>;
+  /** Create or fully replace a UTF-8 text file. */
+  write(args: {
+    /** Path to write, resolved by the filesystem backend. */
+    file_path: string;
+    /** Full UTF-8 text content to write. */
+    content: string;
+    /** The wider sandbox mode this file operation needs. Only valid as a one-shot retry of an operation the sandbox just denied; requires justification and user approval. */
+    sandbox_permissions?: "workspace-write" | "danger-full-access";
+    /** Required with sandbox_permissions: one sentence for the user explaining why this exact file operation needs the wider access. */
+    justification?: string;
+  }): Promise<string>;
 }
 ```

examples/acp-agent/tests/snapshots/both-mode-turn/system-prompt.golden.md

@@ -5,6 +5,12 @@ You are a coding assistant powered by the deepseek-v4-flash model. Your working
 Verify your work by running the code or tests. Keep answers brief and factual.
 
 
+Use the read tool — not shell commands like cat — to inspect text files. Results include line numbers. Use offset and limit to continue reading large files.
+
+Use the write tool to create files or completely replace file contents. Existing files are overwritten, so read an existing file first (the default fs-policy requires it) and prefer edit for targeted changes.
+
+Use the edit tool for targeted changes to existing UTF-8 text files. It replaces literal old_string with new_string; by default old_string must appear exactly once. If old_string appears multiple times, provide a more specific old_string or set replace_all to true. Read the file first (the default fs-policy requires it), unless you just created or edited it in this session.
+
 Check the [exit code: N] marker on every bash result; investigate failures before moving on.
 
 Approval prompts are disabled in this session: actions that require approval are rejected automatically — do not request sandbox escalation (do not set `sandbox_permissions`).
@@ -52,6 +58,30 @@ declare const tools: {
     /** Task id returned by the bash tool. */
     task_id: string;
   }): Promise<string>;
+  /** Edit an existing UTF-8 text file by replacing literal text. */
+  edit(args: {
+    /** Path to edit, resolved by the filesystem backend. */
+    file_path: string;
+    /** Literal text to replace. Must match exactly. */
+    old_string: string;
+    /** Literal replacement text. Use an empty string to delete the match. */
+    new_string: string;
+    /** Replace all matches. Defaults to false; when false, old_string must appear exactly once. */
+    replace_all?: boolean;
+    /** The wider sandbox mode this file operation needs. Only valid as a one-shot retry of an operation the sandbox just denied; requires justification and user approval. */
+    sandbox_permissions?: "workspace-write" | "danger-full-access";
+    /** Required with sandbox_permissions: one sentence for the user explaining why this exact file operation needs the wider access. */
+    justification?: string;
+  }): Promise<string>;
+  /** Read a UTF-8 text file and return line-numbered content. */
+  read(args: {
+    /** Path to read, resolved by the filesystem backend. */
+    file_path: string;
+    /** 1-based first line to return. Defaults to 1. */
+    offset?: number;
+    /** Maximum number of lines to return. Defaults to 2000. */
+    limit?: number;
+  }): Promise<string>;
   /** Load the full instructions for an available skill. Call this with the exact skill name from the session skill catalog before acting on a task that names or clearly matches that skill. */
   skill(args: {
     /** The exact skill name from the available skills list. */
@@ -106,5 +136,16 @@ declare const tools: {
     /** Optional JSON input exposed to the script as the `args` global (wrap a bare list as a field, e.g. {"files": [...]}). */
     args?: Record<string, unknown>;
   }): Promise<string>;
+  /** Create or fully replace a UTF-8 text file. */
+  write(args: {
+    /** Path to write, resolved by the filesystem backend. */
+    file_path: string;
+    /** Full UTF-8 text content to write. */
+    content: string;
+    /** The wider sandbox mode this file operation needs. Only valid as a one-shot retry of an operation the sandbox just denied; requires justification and user approval. */
+    sandbox_permissions?: "workspace-write" | "danger-full-access";
+    /** Required with sandbox_permissions: one sentence for the user explaining why this exact file operation needs the wider access. */
+    justification?: string;
+  }): Promise<string>;
 }
 ```

examples/acp-agent/tests/snapshots/code-mode-turn/system-prompt.golden.md

@@ -5,6 +5,12 @@ You are a coding assistant powered by the deepseek-v4-flash model. Your working
 Verify your work by running the code or tests. Keep answers brief and factual.
 
 
+Use the read tool — not shell commands like cat — to inspect text files. Results include line numbers. Use offset and limit to continue reading large files.
+
+Use the write tool to create files or completely replace file contents. Existing files are overwritten, so read an existing file first (the default fs-policy requires it) and prefer edit for targeted changes.
+
+Use the edit tool for targeted changes to existing UTF-8 text files. It replaces literal old_string with new_string; by default old_string must appear exactly once. If old_string appears multiple times, provide a more specific old_string or set replace_all to true. Read the file first (the default fs-policy requires it), unless you just created or edited it in this session.
+
 Check the [exit code: N] marker on every bash result; investigate failures before moving on.
 
 Approval prompts are disabled in this session: actions that require approval are rejected automatically — do not request sandbox escalation (do not set `sandbox_permissions`).
@@ -52,6 +58,30 @@ declare const tools: {
     /** Task id returned by the bash tool. */
     task_id: string;
   }): Promise<string>;
+  /** Edit an existing UTF-8 text file by replacing literal text. */
+  edit(args: {
+    /** Path to edit, resolved by the filesystem backend. */
+    file_path: string;
+    /** Literal text to replace. Must match exactly. */
+    old_string: string;
+    /** Literal replacement text. Use an empty string to delete the match. */
+    new_string: string;
+    /** Replace all matches. Defaults to false; when false, old_string must appear exactly once. */
+    replace_all?: boolean;
+    /** The wider sandbox mode this file operation needs. Only valid as a one-shot retry of an operation the sandbox just denied; requires justification and user approval. */
+    sandbox_permissions?: "workspace-write" | "danger-full-access";
+    /** Required with sandbox_permissions: one sentence for the user explaining why this exact file operation needs the wider access. */
+    justification?: string;
+  }): Promise<string>;
+  /** Read a UTF-8 text file and return line-numbered content. */
+  read(args: {
+    /** Path to read, resolved by the filesystem backend. */
+    file_path: string;
+    /** 1-based first line to return. Defaults to 1. */
+    offset?: number;
+    /** Maximum number of lines to return. Defaults to 2000. */
+    limit?: number;
+  }): Promise<string>;
   /** Load the full instructions for an available skill. Call this with the exact skill name from the session skill catalog before acting on a task that names or clearly matches that skill. */
   skill(args: {
     /** The exact skill name from the available skills list. */
@@ -106,5 +136,16 @@ declare const tools: {
     /** Optional JSON input exposed to the script as the `args` global (wrap a bare list as a field, e.g. {"files": [...]}). */
     args?: Record<string, unknown>;
   }): Promise<string>;
+  /** Create or fully replace a UTF-8 text file. */
+  write(args: {
+    /** Path to write, resolved by the filesystem backend. */
+    file_path: string;
+    /** Full UTF-8 text content to write. */
+    content: string;
+    /** The wider sandbox mode this file operation needs. Only valid as a one-shot retry of an operation the sandbox just denied; requires justification and user approval. */
+    sandbox_permissions?: "workspace-write" | "danger-full-access";
+    /** Required with sandbox_permissions: one sentence for the user explaining why this exact file operation needs the wider access. */
+    justification?: string;
+  }): Promise<string>;
 }
 ```

examples/acp-agent/tests/snapshots/escalation-approved/session.jsonl

@@ -1,7 +1,7 @@
 {"type":"session","version":0,"id":"f3cbd087-fb45-4b32-b0f2-3082d65bfcb4","createdAt":1783860675270,"cwd":"/var/folders/2g/b32ct0qn1d728l_v6tdkjytr0000gn/T/acp-snap-cwd-cbBLh2"}
 {"type":"turn/start","seq":0,"time":1783860675271,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"permission/preset","seq":1,"time":1783962245380,"data":{"preset":"workspace-write"}}
-{"type":"bash/sandbox-mode","seq":2,"time":1783962245380,"data":{"mode":"workspace-write"}}
+{"type":"sandbox/mode","seq":2,"time":1784023679499,"data":{"mode":"workspace-write"}}
 {"type":"approval/policy","seq":3,"time":1783962245380,"data":{"policy":"ask"}}
 {"type":"user/message","seq":4,"time":1783962245380,"data":{"content":[{"type":"text","text":"The sandbox already denied writing /tmp/dsh-escalated.txt earlier (it is outside this workspace). Retry it now exactly once: one single bash call with the command printf 'escalated\\n' > /tmp/dsh-escalated.txt && cat /tmp/dsh-escalated.txt && rm /tmp/dsh-escalated.txt, with sandbox_permissions set to danger-full-access and the justification 'the user asked to write a file outside the workspace'. Do not run it without sandbox_permissions first. I will approve the permission prompt. After the result, reply with the single word DONE and stop."}],"source":{"kind":"user"}},"surfaceOp":"append"}
 {"type":"step/start","seq":5,"time":1783962245382,"data":{"turn":1,"step":1}}
@@ -131,8 +131,8 @@
 {"type":"assistant/chunk","seq":129,"time":1783962245385,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":130,"time":1783962245385,"data":{"turn":1,"step":1,"content":[{"type":"reasoning","text":"The user wants me to run a command with sandbox_permissions set to danger-full-access, no prior run needed, justified as instructed."},{"type":"tool-call","id":"call_00_d0sAHpJ9mYOJi0z7KNy30441","name":"bash","arguments":"{\"command\": \"printf 'escalated\\\\n' > /tmp/dsh-escalated.txt && cat /tmp/dsh-escalated.txt && rm /tmp/dsh-escalated.txt\", \"description\": \"Write file outside workspace and verify\", \"sandbox_permissions\": \"danger-full-access\", \"justification\": \"the user asked to write a file outside the workspace\"}"}],"usage":{"inputTokens":1501,"outputTokens":174,"cacheReadTokens":0,"reasoningTokens":28}},"sourceEventSeqs":[7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129],"surfaceOp":"append"}
 {"type":"tool/call","seq":131,"time":1783962245385,"data":{"turn":1,"step":1,"callId":"call_00_d0sAHpJ9mYOJi0z7KNy30441","name":"bash","arguments":"{\"command\": \"printf 'escalated\\\\n' > /tmp/dsh-escalated.txt && cat /tmp/dsh-escalated.txt && rm /tmp/dsh-escalated.txt\", \"description\": \"Write file outside workspace and verify\", \"sandbox_permissions\": \"danger-full-access\", \"justification\": \"the user asked to write a file outside the workspace\"}"}}
-{"type":"approval/asked","seq":132,"time":1783962245386,"data":{"id":"d409f075-74f1-4637-9e13-6e80d7b6f6ff","toolName":"bash","callId":"call_00_d0sAHpJ9mYOJi0z7KNy30441","reason":"escalate sandbox to danger-full-access: the user asked to write a file outside the workspace"}}
-{"type":"approval/decided","seq":133,"time":1783962245387,"data":{"id":"d409f075-74f1-4637-9e13-6e80d7b6f6ff","outcome":"allowed-once"}}
+{"type":"approval/asked","seq":132,"time":1783962245386,"data":{"id":"0dfc6fba-ccdf-4233-8b48-87003f0b75b7","toolName":"bash","callId":"call_00_d0sAHpJ9mYOJi0z7KNy30441","reason":"escalate sandbox to danger-full-access: the user asked to write a file outside the workspace"}}
+{"type":"approval/decided","seq":133,"time":1783962245387,"data":{"id":"0dfc6fba-ccdf-4233-8b48-87003f0b75b7","outcome":"allowed-once"}}
 {"type":"tool/result","seq":134,"time":1783962245399,"data":{"turn":1,"step":1,"callId":"call_00_d0sAHpJ9mYOJi0z7KNy30441","content":[{"type":"text","text":"escalated\n"}],"isError":false},"sourceEventSeqs":[131],"surfaceOp":"append"}
 {"type":"step/end","seq":135,"time":1783962245400,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":136,"time":1783962245400,"data":{"turn":1,"step":2}}

examples/acp-agent/tests/snapshots/escalation-rejected/session.jsonl

@@ -1,7 +1,7 @@
 {"type":"session","version":0,"id":"d692fe7f-7079-4ee4-8b06-f44fd026d4ea","createdAt":1783860679475,"cwd":"/var/folders/2g/b32ct0qn1d728l_v6tdkjytr0000gn/T/acp-snap-cwd-Hn29Od"}
 {"type":"turn/start","seq":0,"time":1783860679476,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"permission/preset","seq":1,"time":1783962246267,"data":{"preset":"workspace-write"}}
-{"type":"bash/sandbox-mode","seq":2,"time":1783962246267,"data":{"mode":"workspace-write"}}
+{"type":"sandbox/mode","seq":2,"time":1784023680100,"data":{"mode":"workspace-write"}}
 {"type":"approval/policy","seq":3,"time":1783962246267,"data":{"policy":"ask"}}
 {"type":"user/message","seq":4,"time":1783962246267,"data":{"content":[{"type":"text","text":"The sandbox already denied writing /tmp/dsh-escalated.txt earlier (it is outside this workspace). Retry it now exactly once: one single bash call with the command printf 'escalated\\n' > /tmp/dsh-escalated.txt && cat /tmp/dsh-escalated.txt && rm /tmp/dsh-escalated.txt, with sandbox_permissions set to danger-full-access and the justification 'the user asked to write a file outside the workspace'. Do not run it without sandbox_permissions first. I will reject the permission prompt; after the rejection, do not retry and do not work around it — explain in one short sentence and stop."}],"source":{"kind":"user"}},"surfaceOp":"append"}
 {"type":"step/start","seq":5,"time":1783962246269,"data":{"turn":1,"step":1}}
@@ -155,8 +155,8 @@
 {"type":"assistant/chunk","seq":153,"time":1783962246274,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":154,"time":1783962246274,"data":{"turn":1,"step":1,"content":[{"type":"reasoning","text":"The user wants me to run a specific command with `sandbox_permissions` set to `danger-full-access` and a specific justification. They explicitly said NOT to run it without sandbox_permissions first. Let me do exactly that."},{"type":"tool-call","id":"call_00_WB1vnPomi8yr6MlcFKTj7912","name":"bash","arguments":"{\"command\": \"printf 'escalated\\\\n' > /tmp/dsh-escalated.txt && cat /tmp/dsh-escalated.txt && rm /tmp/dsh-escalated.txt\", \"description\": \"Write to /tmp and verify, then clean up\", \"sandbox_permissions\": \"danger-full-access\", \"justification\": \"the user asked to write a file outside the workspace\"}"}],"usage":{"inputTokens":1509,"outputTokens":198,"cacheReadTokens":0,"reasoningTokens":48}},"sourceEventSeqs":[7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153],"surfaceOp":"append"}
 {"type":"tool/call","seq":155,"time":1783962246274,"data":{"turn":1,"step":1,"callId":"call_00_WB1vnPomi8yr6MlcFKTj7912","name":"bash","arguments":"{\"command\": \"printf 'escalated\\\\n' > /tmp/dsh-escalated.txt && cat /tmp/dsh-escalated.txt && rm /tmp/dsh-escalated.txt\", \"description\": \"Write to /tmp and verify, then clean up\", \"sandbox_permissions\": \"danger-full-access\", \"justification\": \"the user asked to write a file outside the workspace\"}"}}
-{"type":"approval/asked","seq":156,"time":1783962246275,"data":{"id":"e592115c-e915-4010-9bf5-cc5e7bb6f8bc","toolName":"bash","callId":"call_00_WB1vnPomi8yr6MlcFKTj7912","reason":"escalate sandbox to danger-full-access: the user asked to write a file outside the workspace"}}
-{"type":"approval/decided","seq":157,"time":1783962246275,"data":{"id":"e592115c-e915-4010-9bf5-cc5e7bb6f8bc","outcome":"rejected"}}
+{"type":"approval/asked","seq":156,"time":1783962246275,"data":{"id":"5b59a78f-4b4c-400b-b7f7-d8f689f75854","toolName":"bash","callId":"call_00_WB1vnPomi8yr6MlcFKTj7912","reason":"escalate sandbox to danger-full-access: the user asked to write a file outside the workspace"}}
+{"type":"approval/decided","seq":157,"time":1783962246275,"data":{"id":"5b59a78f-4b4c-400b-b7f7-d8f689f75854","outcome":"rejected"}}
 {"type":"tool/result","seq":158,"time":1783962246275,"data":{"turn":1,"step":1,"callId":"call_00_WB1vnPomi8yr6MlcFKTj7912","content":[{"type":"text","text":"Error: the user rejected escalating this command to \"danger-full-access\""}],"isError":true},"sourceEventSeqs":[155],"surfaceOp":"append"}
 {"type":"step/end","seq":159,"time":1783962246276,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":160,"time":1783962246276,"data":{"turn":1,"step":2}}

examples/acp-agent/tests/snapshots/fs-edit/session.jsonl

@@ -69,7 +69,7 @@
 {"type":"assistant/chunk","seq":67,"time":1783352086057,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":68,"time":1783352086059,"data":{"turn":1,"step":1,"content":[{"type":"reasoning","text":"The user wants me to:\n1. Read config.txt in the current directory\n2. Use the edit tool to replace DEBUG with RELEASE\n3. Reply with exactly \"DONE\"\n\nLet me start by reading the file."},{"type":"tool-call","id":"call_00_S6krdIDHoSCGWv7WnXX97617","name":"read","arguments":"{\"file_path\": \"config.txt\"}"}],"usage":{"inputTokens":2900,"outputTokens":91,"cacheReadTokens":0,"reasoningTokens":46}},"sourceEventSeqs":[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67],"surfaceOp":"append"}
 {"type":"tool/call","seq":69,"time":1783352086059,"data":{"turn":1,"step":1,"callId":"call_00_S6krdIDHoSCGWv7WnXX97617","name":"read","arguments":"{\"file_path\": \"config.txt\"}"}}
-{"type":"tool/result","seq":70,"time":1783352086065,"data":{"turn":1,"step":1,"callId":"call_00_S6krdIDHoSCGWv7WnXX97617","content":[{"type":"text","text":"Error: unknown tool \"read\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[69],"surfaceOp":"append"}
+{"type":"tool/result","seq":70,"time":1783352086065,"data":{"turn":1,"step":1,"callId":"call_00_S6krdIDHoSCGWv7WnXX97617","content":[{"type":"text","text":"<path>/tmp/acp-snap-cwd-0BxHdV/config.txt</path>\n<type>file</type>\n<content>\n1: mode=DEBUG\n2: level=info\n\n(End of file - total 2 lines)\n</content>"}],"isError":false},"sourceEventSeqs":[69],"surfaceOp":"append"}
 {"type":"step/end","seq":71,"time":1783352086065,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":72,"time":1783352086066,"data":{"turn":1,"step":2}}
 {"type":"assistant/chunk","seq":73,"time":1783352086901,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}
@@ -129,7 +129,7 @@
 {"type":"assistant/chunk","seq":127,"time":1783352087469,"data":{"turn":1,"step":2,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":128,"time":1783352087469,"data":{"turn":1,"step":2,"content":[{"type":"reasoning","text":"Now I need to replace \"DEBUG\" with \"RELEASE\" using the edit tool."},{"type":"tool-call","id":"call_00_vOytneZ0XpsLslEEJAxR6398","name":"edit","arguments":"{\"file_path\": \"config.txt\", \"old_string\": \"DEBUG\", \"new_string\": \"RELEASE\"}"}],"usage":{"inputTokens":241,"outputTokens":98,"cacheReadTokens":2816,"reasoningTokens":18}},"sourceEventSeqs":[73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127],"surfaceOp":"append"}
 {"type":"tool/call","seq":129,"time":1783352087469,"data":{"turn":1,"step":2,"callId":"call_00_vOytneZ0XpsLslEEJAxR6398","name":"edit","arguments":"{\"file_path\": \"config.txt\", \"old_string\": \"DEBUG\", \"new_string\": \"RELEASE\"}"}}
-{"type":"tool/result","seq":130,"time":1783352087476,"data":{"turn":1,"step":2,"callId":"call_00_vOytneZ0XpsLslEEJAxR6398","content":[{"type":"text","text":"Error: unknown tool \"edit\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[129],"surfaceOp":"append"}
+{"type":"tool/result","seq":130,"time":1783352087476,"data":{"turn":1,"step":2,"callId":"call_00_vOytneZ0XpsLslEEJAxR6398","content":[{"type":"text","text":"The file /tmp/acp-snap-cwd-0BxHdV/config.txt has been updated successfully."}],"isError":false,"meta":{"diffs":[{"path":"config.txt","oldText":"mode=DEBUG\nlevel=info","newText":"mode=RELEASE\nlevel=info"}]}},"sourceEventSeqs":[129],"surfaceOp":"append"}
 {"type":"step/end","seq":131,"time":1783352087477,"data":{"turn":1,"step":2}}
 {"type":"step/start","seq":132,"time":1783352087477,"data":{"turn":1,"step":3}}
 {"type":"assistant/chunk","seq":133,"time":1783352088286,"data":{"turn":1,"step":3,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}

examples/acp-agent/tests/snapshots/fs-edit/stdout.golden.jsonl

@@ -46,8 +46,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" the"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" file"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_S6krdIDHoSCGWv7WnXX97617","title":"read","kind":"other","status":"in_progress","rawInput":{"file_path":"config.txt"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_S6krdIDHoSCGWv7WnXX97617","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"read\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_S6krdIDHoSCGWv7WnXX97617","title":"Read config.txt","kind":"read","status":"in_progress","locations":[{"path":"config.txt","line":1}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_S6krdIDHoSCGWv7WnXX97617","status":"completed","content":[{"type":"content","content":{"type":"text","text":"<path>{{cwd}}/config.txt</path>\n<type>file</type>\n<content>\n1: mode=DEBUG\n2: level=info\n\n(End of file - total 2 lines)\n</content>"}}]}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"Now"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" I"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" need"}}}}
@@ -66,8 +66,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" edit"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" tool"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_vOytneZ0XpsLslEEJAxR6398","title":"edit","kind":"other","status":"in_progress","rawInput":{"file_path":"config.txt","old_string":"DEBUG","new_string":"RELEASE"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_vOytneZ0XpsLslEEJAxR6398","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"edit\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_vOytneZ0XpsLslEEJAxR6398","title":"Edit config.txt","kind":"edit","status":"in_progress","locations":[{"path":"config.txt"}],"content":[{"type":"diff","path":"config.txt","oldText":"DEBUG","newText":"RELEASE"}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_vOytneZ0XpsLslEEJAxR6398","status":"completed","content":[{"type":"diff","path":"config.txt","oldText":"mode=DEBUG\nlevel=info","newText":"mode=RELEASE\nlevel=info"}],"title":"Edit config.txt"}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"Done"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"."}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" The"}}}}

examples/acp-agent/tests/snapshots/fs-policy-reject/session.jsonl

@@ -77,7 +77,7 @@
 {"type":"assistant/chunk","seq":75,"time":1783611703969,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":76,"time":1783611703972,"data":{"turn":1,"step":1,"content":[{"type":"reasoning","text":"The user wants me to use the edit tool to replace \"blue\" with \"green\" in settings.txt without reading the file first, and then reply with just \"DONE\"."},{"type":"tool-call","id":"call_00_x0zlnXl5JOxLrAYL9y7P0119","name":"edit","arguments":"{\"file_path\": \"settings.txt\", \"old_string\": \"blue\", \"new_string\": \"green\"}"}],"usage":{"inputTokens":3132,"outputTokens":115,"cacheReadTokens":0,"reasoningTokens":36}},"sourceEventSeqs":[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75],"surfaceOp":"append"}
 {"type":"tool/call","seq":77,"time":1783611703972,"data":{"turn":1,"step":1,"callId":"call_00_x0zlnXl5JOxLrAYL9y7P0119","name":"edit","arguments":"{\"file_path\": \"settings.txt\", \"old_string\": \"blue\", \"new_string\": \"green\"}"}}
-{"type":"tool/result","seq":78,"time":1783611703978,"data":{"turn":1,"step":1,"callId":"call_00_x0zlnXl5JOxLrAYL9y7P0119","content":[{"type":"text","text":"Error: unknown tool \"edit\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[77],"surfaceOp":"append"}
+{"type":"tool/result","seq":78,"time":1783611703978,"data":{"turn":1,"step":1,"callId":"call_00_x0zlnXl5JOxLrAYL9y7P0119","content":[{"type":"text","text":"Error: edit requires reading \"/var/folders/2c/psb0_fmx7hbgz558xjt_f0l00000gn/T/acp-snap-cwd-QzoqnB/settings.txt\" first"}],"isError":true,"error":{"name":"FsError","code":"FS_NOT_OBSERVED"}},"sourceEventSeqs":[77],"surfaceOp":"append"}
 {"type":"step/end","seq":79,"time":1783611703978,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":80,"time":1783611703978,"data":{"turn":1,"step":2}}
 {"type":"assistant/chunk","seq":81,"time":1783611704825,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}
@@ -144,7 +144,7 @@
 {"type":"assistant/chunk","seq":142,"time":1783611705572,"data":{"turn":1,"step":2,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":143,"time":1783611705573,"data":{"turn":1,"step":2,"content":[{"type":"reasoning","text":"The edit tool requires reading the file first. The user said \"Do not read the file first\" but the tool's own constraints require reading. I need to follow the tool requirements. Let me read the file first."},{"type":"tool-call","id":"call_00_tfr0gdIclW92oIEgi7NF0891","name":"read","arguments":"{\"file_path\": \"settings.txt\"}"}],"usage":{"inputTokens":235,"outputTokens":89,"cacheReadTokens":3072,"reasoningTokens":44}},"sourceEventSeqs":[81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142],"surfaceOp":"append"}
 {"type":"tool/call","seq":144,"time":1783611705573,"data":{"turn":1,"step":2,"callId":"call_00_tfr0gdIclW92oIEgi7NF0891","name":"read","arguments":"{\"file_path\": \"settings.txt\"}"}}
-{"type":"tool/result","seq":145,"time":1783611705579,"data":{"turn":1,"step":2,"callId":"call_00_tfr0gdIclW92oIEgi7NF0891","content":[{"type":"text","text":"Error: unknown tool \"read\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[144],"surfaceOp":"append"}
+{"type":"tool/result","seq":145,"time":1783611705579,"data":{"turn":1,"step":2,"callId":"call_00_tfr0gdIclW92oIEgi7NF0891","content":[{"type":"text","text":"<path>/var/folders/2c/psb0_fmx7hbgz558xjt_f0l00000gn/T/acp-snap-cwd-QzoqnB/settings.txt</path>\n<type>file</type>\n<content>\n1: color: blue\n\n(End of file - total 1 lines)\n</content>"}],"isError":false},"sourceEventSeqs":[144],"surfaceOp":"append"}
 {"type":"step/end","seq":146,"time":1783611705579,"data":{"turn":1,"step":2}}
 {"type":"step/start","seq":147,"time":1783611705579,"data":{"turn":1,"step":3}}
 {"type":"assistant/chunk","seq":148,"time":1783611706200,"data":{"turn":1,"step":3,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}
@@ -225,7 +225,7 @@
 {"type":"assistant/chunk","seq":223,"time":1783611707096,"data":{"turn":1,"step":3,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":224,"time":1783611707097,"data":{"turn":1,"step":3,"content":[{"type":"reasoning","text":"The file contains \"color: blue\". I need to replace \"blue\" with \"green\". The edit tool said it requires reading first — now I've read it, so the edit should work."},{"type":"tool-call","id":"call_00_GVknJu2tksKkP4lALCwh0926","name":"edit","arguments":"{\"file_path\": \"settings.txt\", \"old_string\": \"blue\", \"new_string\": \"green\"}"}],"usage":{"inputTokens":281,"outputTokens":119,"cacheReadTokens":3200,"reasoningTokens":40}},"sourceEventSeqs":[148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223],"surfaceOp":"append"}
 {"type":"tool/call","seq":225,"time":1783611707097,"data":{"turn":1,"step":3,"callId":"call_00_GVknJu2tksKkP4lALCwh0926","name":"edit","arguments":"{\"file_path\": \"settings.txt\", \"old_string\": \"blue\", \"new_string\": \"green\"}"}}
-{"type":"tool/result","seq":226,"time":1783611707114,"data":{"turn":1,"step":3,"callId":"call_00_GVknJu2tksKkP4lALCwh0926","content":[{"type":"text","text":"Error: unknown tool \"edit\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[225],"surfaceOp":"append"}
+{"type":"tool/result","seq":226,"time":1783611707114,"data":{"turn":1,"step":3,"callId":"call_00_GVknJu2tksKkP4lALCwh0926","content":[{"type":"text","text":"The file /var/folders/2c/psb0_fmx7hbgz558xjt_f0l00000gn/T/acp-snap-cwd-QzoqnB/settings.txt has been updated successfully."}],"isError":false,"meta":{"diffs":[{"path":"settings.txt","oldText":"color: blue","newText":"color: green"}]}},"sourceEventSeqs":[225],"surfaceOp":"append"}
 {"type":"step/end","seq":227,"time":1783611707114,"data":{"turn":1,"step":3}}
 {"type":"step/start","seq":228,"time":1783611707114,"data":{"turn":1,"step":4}}
 {"type":"assistant/chunk","seq":229,"time":1783611707747,"data":{"turn":1,"step":4,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}

examples/acp-agent/tests/snapshots/fs-policy-reject/stdout.golden.jsonl

@@ -36,8 +36,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"D"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"ONE"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"\"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_x0zlnXl5JOxLrAYL9y7P0119","title":"edit","kind":"other","status":"in_progress","rawInput":{"file_path":"settings.txt","old_string":"blue","new_string":"green"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_x0zlnXl5JOxLrAYL9y7P0119","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"edit\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_x0zlnXl5JOxLrAYL9y7P0119","title":"Edit settings.txt","kind":"edit","status":"in_progress","locations":[{"path":"settings.txt"}],"content":[{"type":"diff","path":"settings.txt","oldText":"blue","newText":"green"}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_x0zlnXl5JOxLrAYL9y7P0119","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: edit requires reading \"{{cwd}}/settings.txt\" first"}}]}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"The"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" edit"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" tool"}}}}
@@ -82,8 +82,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" file"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" first"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_tfr0gdIclW92oIEgi7NF0891","title":"read","kind":"other","status":"in_progress","rawInput":{"file_path":"settings.txt"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_tfr0gdIclW92oIEgi7NF0891","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"read\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_tfr0gdIclW92oIEgi7NF0891","title":"Read settings.txt","kind":"read","status":"in_progress","locations":[{"path":"settings.txt","line":1}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_tfr0gdIclW92oIEgi7NF0891","status":"completed","content":[{"type":"content","content":{"type":"text","text":"<path>{{cwd}}/settings.txt</path>\n<type>file</type>\n<content>\n1: color: blue\n\n(End of file - total 1 lines)\n</content>"}}]}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"The"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" file"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" contains"}}}}
@@ -124,8 +124,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" should"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" work"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_GVknJu2tksKkP4lALCwh0926","title":"edit","kind":"other","status":"in_progress","rawInput":{"file_path":"settings.txt","old_string":"blue","new_string":"green"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_GVknJu2tksKkP4lALCwh0926","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"edit\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_GVknJu2tksKkP4lALCwh0926","title":"Edit settings.txt","kind":"edit","status":"in_progress","locations":[{"path":"settings.txt"}],"content":[{"type":"diff","path":"settings.txt","oldText":"blue","newText":"green"}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_GVknJu2tksKkP4lALCwh0926","status":"completed","content":[{"type":"diff","path":"settings.txt","oldText":"color: blue","newText":"color: green"}],"title":"Edit settings.txt"}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"The"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" replacement"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" was"}}}}

examples/acp-agent/tests/snapshots/fs-read-window/session.jsonl

@@ -91,7 +91,7 @@
 {"type":"assistant/chunk","seq":89,"time":1783352101346,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":90,"time":1783352101348,"data":{"turn":1,"step":1,"content":[{"type":"reasoning","text":"The user wants me to use the read tool with offset 5 and limit 4 to read lines 5 through 8 of big.txt in the current directory. Then reply with exactly the single word DONE.\n\nLet me first check the current directory, then read the file."},{"type":"tool-call","id":"call_00_GIZwZS9a7vhWTFCIc7Z35497","name":"read","arguments":"{\"file_path\": \"big.txt\", \"offset\": 5, \"limit\": 4}"}],"usage":{"inputTokens":2894,"outputTokens":133,"cacheReadTokens":0,"reasoningTokens":56}},"sourceEventSeqs":[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89],"surfaceOp":"append"}
 {"type":"tool/call","seq":91,"time":1783352101348,"data":{"turn":1,"step":1,"callId":"call_00_GIZwZS9a7vhWTFCIc7Z35497","name":"read","arguments":"{\"file_path\": \"big.txt\", \"offset\": 5, \"limit\": 4}"}}
-{"type":"tool/result","seq":92,"time":1783352101353,"data":{"turn":1,"step":1,"callId":"call_00_GIZwZS9a7vhWTFCIc7Z35497","content":[{"type":"text","text":"Error: unknown tool \"read\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[91],"surfaceOp":"append"}
+{"type":"tool/result","seq":92,"time":1783352101353,"data":{"turn":1,"step":1,"callId":"call_00_GIZwZS9a7vhWTFCIc7Z35497","content":[{"type":"text","text":"<path>/tmp/acp-snap-cwd-N9HCkt/big.txt</path>\n<type>file</type>\n<content>\n5: line five\n6: line six\n7: line seven\n8: line eight\n\n(Showing lines 5-8 of 10. Use offset=9 to continue.)\n</content>"}],"isError":false},"sourceEventSeqs":[91],"surfaceOp":"append"}
 {"type":"step/end","seq":93,"time":1783352101353,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":94,"time":1783352101354,"data":{"turn":1,"step":2}}
 {"type":"assistant/chunk","seq":95,"time":1783352102021,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}

examples/acp-agent/tests/snapshots/fs-read-window/stdout.golden.jsonl

@@ -56,8 +56,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" the"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" file"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_GIZwZS9a7vhWTFCIc7Z35497","title":"read","kind":"other","status":"in_progress","rawInput":{"file_path":"big.txt","offset":5,"limit":4}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_GIZwZS9a7vhWTFCIc7Z35497","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"read\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_GIZwZS9a7vhWTFCIc7Z35497","title":"Read big.txt (5 - 8)","kind":"read","status":"in_progress","locations":[{"path":"big.txt","line":5}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_GIZwZS9a7vhWTFCIc7Z35497","status":"completed","content":[{"type":"content","content":{"type":"text","text":"<path>{{cwd}}/big.txt</path>\n<type>file</type>\n<content>\n5: line five\n6: line six\n7: line seven\n8: line eight\n\n(Showing lines 5-8 of 10. Use offset=9 to continue.)\n</content>"}}]}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"The"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" read"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" tool"}}}}

examples/acp-agent/tests/snapshots/fs-read/session.jsonl

@@ -53,7 +53,7 @@
 {"type":"assistant/chunk","seq":51,"time":1783352073705,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":52,"time":1783352073708,"data":{"turn":1,"step":1,"content":[{"type":"reasoning","text":"The user wants me to read the file greeting.txt using the read tool (not bash), then reply with exactly the single word \"DONE\"."},{"type":"tool-call","id":"call_00_hHPZCcivsIkXAGS9jTGy8417","name":"read","arguments":"{\"file_path\": \"greeting.txt\"}"}],"usage":{"inputTokens":2882,"outputTokens":75,"cacheReadTokens":0,"reasoningTokens":29}},"sourceEventSeqs":[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51],"surfaceOp":"append"}
 {"type":"tool/call","seq":53,"time":1783352073709,"data":{"turn":1,"step":1,"callId":"call_00_hHPZCcivsIkXAGS9jTGy8417","name":"read","arguments":"{\"file_path\": \"greeting.txt\"}"}}
-{"type":"tool/result","seq":54,"time":1783352073717,"data":{"turn":1,"step":1,"callId":"call_00_hHPZCcivsIkXAGS9jTGy8417","content":[{"type":"text","text":"Error: unknown tool \"read\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[53],"surfaceOp":"append"}
+{"type":"tool/result","seq":54,"time":1783352073717,"data":{"turn":1,"step":1,"callId":"call_00_hHPZCcivsIkXAGS9jTGy8417","content":[{"type":"text","text":"<path>/tmp/acp-snap-cwd-PEETkS/greeting.txt</path>\n<type>file</type>\n<content>\n1: hello\n\n(End of file - total 1 lines)\n</content>"}],"isError":false},"sourceEventSeqs":[53],"surfaceOp":"append"}
 {"type":"step/end","seq":55,"time":1783352073718,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":56,"time":1783352073719,"data":{"turn":1,"step":2}}
 {"type":"assistant/chunk","seq":57,"time":1783352074666,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}

examples/acp-agent/tests/snapshots/fs-read/stdout.golden.jsonl

@@ -29,8 +29,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"D"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"ONE"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"\"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_hHPZCcivsIkXAGS9jTGy8417","title":"read","kind":"other","status":"in_progress","rawInput":{"file_path":"greeting.txt"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_hHPZCcivsIkXAGS9jTGy8417","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"read\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_hHPZCcivsIkXAGS9jTGy8417","title":"Read greeting.txt","kind":"read","status":"in_progress","locations":[{"path":"greeting.txt","line":1}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_hHPZCcivsIkXAGS9jTGy8417","status":"completed","content":[{"type":"content","content":{"type":"text","text":"<path>{{cwd}}/greeting.txt</path>\n<type>file</type>\n<content>\n1: hello\n\n(End of file - total 1 lines)\n</content>"}}]}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"The"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" user"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" asked"}}}}

examples/acp-agent/tests/snapshots/fs-write-overwrite/session.jsonl

@@ -65,7 +65,7 @@
 {"type":"assistant/chunk","seq":63,"time":1783352093614,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":64,"time":1783352093617,"data":{"turn":1,"step":1,"content":[{"type":"reasoning","text":"The user wants me to:\n1. Read data.txt using the read tool\n2. Replace its entire contents with exactly \"replaced\" using the write tool\n3. Reply with exactly \"DONE\""},{"type":"tool-call","id":"call_00_n4eRJuGoxNR07svgNtk82243","name":"read","arguments":"{\"file_path\": \"data.txt\"}"}],"usage":{"inputTokens":2899,"outputTokens":87,"cacheReadTokens":0,"reasoningTokens":42}},"sourceEventSeqs":[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63],"surfaceOp":"append"}
 {"type":"tool/call","seq":65,"time":1783352093617,"data":{"turn":1,"step":1,"callId":"call_00_n4eRJuGoxNR07svgNtk82243","name":"read","arguments":"{\"file_path\": \"data.txt\"}"}}
-{"type":"tool/result","seq":66,"time":1783352093624,"data":{"turn":1,"step":1,"callId":"call_00_n4eRJuGoxNR07svgNtk82243","content":[{"type":"text","text":"Error: unknown tool \"read\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[65],"surfaceOp":"append"}
+{"type":"tool/result","seq":66,"time":1783352093624,"data":{"turn":1,"step":1,"callId":"call_00_n4eRJuGoxNR07svgNtk82243","content":[{"type":"text","text":"<path>/tmp/acp-snap-cwd-hH2sGY/data.txt</path>\n<type>file</type>\n<content>\n1: original contents\n\n(End of file - total 1 lines)\n</content>"}],"isError":false},"sourceEventSeqs":[65],"surfaceOp":"append"}
 {"type":"step/end","seq":67,"time":1783352093624,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":68,"time":1783352093625,"data":{"turn":1,"step":2}}
 {"type":"assistant/chunk","seq":69,"time":1783352094455,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}
@@ -114,7 +114,7 @@
 {"type":"assistant/chunk","seq":112,"time":1783352094988,"data":{"turn":1,"step":2,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":113,"time":1783352094988,"data":{"turn":1,"step":2,"content":[{"type":"reasoning","text":"The file contains \"original contents\". Now I'll replace it with \"replaced\"."},{"type":"tool-call","id":"call_00_N23EvXjDo4c8enyWpIUq4043","name":"write","arguments":"{\"file_path\": \"data.txt\", \"content\": \"replaced\"}"}],"usage":{"inputTokens":228,"outputTokens":79,"cacheReadTokens":2816,"reasoningTokens":17}},"sourceEventSeqs":[69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112],"surfaceOp":"append"}
 {"type":"tool/call","seq":114,"time":1783352094988,"data":{"turn":1,"step":2,"callId":"call_00_N23EvXjDo4c8enyWpIUq4043","name":"write","arguments":"{\"file_path\": \"data.txt\", \"content\": \"replaced\"}"}}
-{"type":"tool/result","seq":115,"time":1783352094995,"data":{"turn":1,"step":2,"callId":"call_00_N23EvXjDo4c8enyWpIUq4043","content":[{"type":"text","text":"Error: unknown tool \"write\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[114],"surfaceOp":"append"}
+{"type":"tool/result","seq":115,"time":1783352094995,"data":{"turn":1,"step":2,"callId":"call_00_N23EvXjDo4c8enyWpIUq4043","content":[{"type":"text","text":"<path>/tmp/acp-snap-cwd-hH2sGY/data.txt</path>\n<type>file</type>\n<content>\nUpdated file\n</content>"}],"isError":false,"meta":{"diffs":[{"path":"data.txt","oldText":"original contents","newText":"replaced"}]}},"sourceEventSeqs":[114],"surfaceOp":"append"}
 {"type":"step/end","seq":116,"time":1783352094995,"data":{"turn":1,"step":2}}
 {"type":"step/start","seq":117,"time":1783352094995,"data":{"turn":1,"step":3}}
 {"type":"assistant/chunk","seq":118,"time":1783352096090,"data":{"turn":1,"step":3,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}

examples/acp-agent/tests/snapshots/fs-write-overwrite/stdout.golden.jsonl

@@ -42,8 +42,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"D"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"ONE"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"\""}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_n4eRJuGoxNR07svgNtk82243","title":"read","kind":"other","status":"in_progress","rawInput":{"file_path":"data.txt"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_n4eRJuGoxNR07svgNtk82243","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"read\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_n4eRJuGoxNR07svgNtk82243","title":"Read data.txt","kind":"read","status":"in_progress","locations":[{"path":"data.txt","line":1}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_n4eRJuGoxNR07svgNtk82243","status":"completed","content":[{"type":"content","content":{"type":"text","text":"<path>{{cwd}}/data.txt</path>\n<type>file</type>\n<content>\n1: original contents\n\n(End of file - total 1 lines)\n</content>"}}]}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"The"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" file"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" contains"}}}}
@@ -61,8 +61,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"re"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"placed"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"\"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_N23EvXjDo4c8enyWpIUq4043","title":"write","kind":"other","status":"in_progress","rawInput":{"file_path":"data.txt","content":"replaced"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_N23EvXjDo4c8enyWpIUq4043","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"write\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_N23EvXjDo4c8enyWpIUq4043","title":"Write data.txt","kind":"edit","status":"in_progress","locations":[{"path":"data.txt"}],"content":[{"type":"diff","path":"data.txt","oldText":null,"newText":"replaced"}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_N23EvXjDo4c8enyWpIUq4043","status":"completed","content":[{"type":"diff","path":"data.txt","oldText":"original contents","newText":"replaced"}],"title":"Write data.txt"}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"The"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" file"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" has"}}}}

examples/acp-agent/tests/snapshots/fs-write/session.jsonl

@@ -62,7 +62,7 @@
 {"type":"assistant/chunk","seq":60,"time":1783352079886,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":61,"time":1783352079888,"data":{"turn":1,"step":1,"content":[{"type":"reasoning","text":"The user wants me to create a file named notes.txt with the content \"hello world\" using the write tool, then reply with \"DONE\"."},{"type":"tool-call","id":"call_00_APMUCJJm9lrTSlVbg6dB0185","name":"write","arguments":"{\"file_path\": \"notes.txt\", \"content\": \"hello world\"}"}],"usage":{"inputTokens":2891,"outputTokens":92,"cacheReadTokens":0,"reasoningTokens":30}},"sourceEventSeqs":[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60],"surfaceOp":"append"}
 {"type":"tool/call","seq":62,"time":1783352079888,"data":{"turn":1,"step":1,"callId":"call_00_APMUCJJm9lrTSlVbg6dB0185","name":"write","arguments":"{\"file_path\": \"notes.txt\", \"content\": \"hello world\"}"}}
-{"type":"tool/result","seq":63,"time":1783352079897,"data":{"turn":1,"step":1,"callId":"call_00_APMUCJJm9lrTSlVbg6dB0185","content":[{"type":"text","text":"Error: unknown tool \"write\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[62],"surfaceOp":"append"}
+{"type":"tool/result","seq":63,"time":1783352079897,"data":{"turn":1,"step":1,"callId":"call_00_APMUCJJm9lrTSlVbg6dB0185","content":[{"type":"text","text":"<path>/tmp/acp-snap-cwd-sNvn5N/notes.txt</path>\n<type>file</type>\n<content>\nCreated file\n</content>"}],"isError":false},"sourceEventSeqs":[62],"surfaceOp":"append"}
 {"type":"step/end","seq":64,"time":1783352079898,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":65,"time":1783352079899,"data":{"turn":1,"step":2}}
 {"type":"assistant/chunk","seq":66,"time":1783352080825,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}

examples/acp-agent/tests/snapshots/fs-write/stdout.golden.jsonl

@@ -30,8 +30,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"D"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"ONE"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"\"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_APMUCJJm9lrTSlVbg6dB0185","title":"write","kind":"other","status":"in_progress","rawInput":{"file_path":"notes.txt","content":"hello world"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_APMUCJJm9lrTSlVbg6dB0185","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"write\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_APMUCJJm9lrTSlVbg6dB0185","title":"Write notes.txt","kind":"edit","status":"in_progress","locations":[{"path":"notes.txt"}],"content":[{"type":"diff","path":"notes.txt","oldText":null,"newText":"hello world"}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_APMUCJJm9lrTSlVbg6dB0185","status":"completed","content":[{"type":"diff","path":"notes.txt","oldText":null,"newText":"hello world"}],"title":"Write notes.txt"}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"The"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" file"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" has"}}}}

examples/acp-agent/tests/snapshots/hook-cc-pretool-ask/session.jsonl

@@ -55,8 +55,8 @@
 {"type":"tool/call","seq":53,"time":1783352172557,"data":{"turn":1,"step":1,"callId":"call_00_6k0oGSliVHxGSgqBmMEO4311","name":"bash","arguments":"{\"command\": \"echo HELLO\", \"description\": \"Echo HELLO\"}"}}
 {"type":"hook/invoked","seq":54,"time":1783352172558,"data":{"turn":1,"point":"PreToolUse","dialect":"claude","handlerId":"claude:PreToolUse:1","matcher":"bash"}}
 {"type":"hook/result","seq":55,"time":1783352172573,"data":{"turn":1,"point":"PreToolUse","handlerId":"claude:PreToolUse:1","decision":"ask","exitCode":0,"durationMs":14.113374999999905}}
-{"type":"approval/asked","seq":56,"time":1783962235813,"data":{"id":"cdd11a3a-c721-4d08-8255-732218775c33","toolName":"bash","callId":"call_00_6k0oGSliVHxGSgqBmMEO4311","reason":"bash requires manual approval in this session"}}
-{"type":"approval/decided","seq":57,"time":1783962235813,"data":{"id":"cdd11a3a-c721-4d08-8255-732218775c33","outcome":"rejected"}}
+{"type":"approval/asked","seq":56,"time":1783962235813,"data":{"id":"f8f9d54e-a313-4719-9950-713e317b29b7","toolName":"bash","callId":"call_00_6k0oGSliVHxGSgqBmMEO4311","reason":"bash requires manual approval in this session"}}
+{"type":"approval/decided","seq":57,"time":1783962235813,"data":{"id":"f8f9d54e-a313-4719-9950-713e317b29b7","outcome":"rejected"}}
 {"type":"tool/result","seq":58,"time":1783962235814,"data":{"turn":1,"step":1,"callId":"call_00_6k0oGSliVHxGSgqBmMEO4311","content":[{"type":"text","text":"Error: the user rejected tool \"bash\""}],"isError":true},"sourceEventSeqs":[53],"surfaceOp":"append"}
 {"type":"step/end","seq":59,"time":1783962235814,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":60,"time":1783962235814,"data":{"turn":1,"step":2}}

examples/acp-agent/tests/snapshots/permission-switching/system-prompt.golden.md

@@ -5,13 +5,19 @@ You are a coding assistant powered by the deepseek-v4-flash model. Your working
 Verify your work by running the code or tests. Keep answers brief and factual.
 
 
+Use the read tool — not shell commands like cat — to inspect text files. Results include line numbers. Use offset and limit to continue reading large files.
+
+Use the write tool to create files or completely replace file contents. Existing files are overwritten, so read an existing file first (the default fs-policy requires it) and prefer edit for targeted changes.
+
+Use the edit tool for targeted changes to existing UTF-8 text files. It replaces literal old_string with new_string; by default old_string must appear exactly once. If old_string appears multiple times, provide a more specific old_string or set replace_all to true. Read the file first (the default fs-policy requires it), unless you just created or edited it in this session.
+
 Check the [exit code: N] marker on every bash result; investigate failures before moving on.
 
 <!-- dsh-user-approval-policy:ask -->
 
 Use the workflow tool ONLY when the user explicitly asks for a workflow or for large multi-agent orchestration: you write a JavaScript script (the tool description documents the exact format) that fans work out across many subagents with phases and structured results. For one or two delegations, prefer plain subagent calls.
 
-<!-- request/header-delta 1: keepStart=9, keepEnd=2 -->
+<!-- request/header-delta 1: keepStart=15, keepEnd=2 -->
 
 Approval prompts are disabled in this session: actions that require approval are rejected automatically — do not request sandbox escalation (do not set `sandbox_permissions`).
 <!-- dsh-user-approval-policy:never -->

examples/acp-agent/tests/snapshots/skill-load/system-prompt.golden.md

@@ -5,6 +5,12 @@ You are a coding assistant powered by the deepseek-v4-flash model. Your working
 Verify your work by running the code or tests. Keep answers brief and factual.
 
 
+Use the read tool — not shell commands like cat — to inspect text files. Results include line numbers. Use offset and limit to continue reading large files.
+
+Use the write tool to create files or completely replace file contents. Existing files are overwritten, so read an existing file first (the default fs-policy requires it) and prefer edit for targeted changes.
+
+Use the edit tool for targeted changes to existing UTF-8 text files. It replaces literal old_string with new_string; by default old_string must appear exactly once. If old_string appears multiple times, provide a more specific old_string or set replace_all to true. Read the file first (the default fs-policy requires it), unless you just created or edited it in this session.
+
 Check the [exit code: N] marker on every bash result; investigate failures before moving on.
 
 Approval prompts are disabled in this session: actions that require approval are rejected automatically — do not request sandbox escalation (do not set `sandbox_permissions`).

examples/acp-agent/tests/snapshots/text-turn/system-prompt.golden.md

@@ -5,6 +5,12 @@ You are a coding assistant powered by the deepseek-v4-flash model. Your working
 Verify your work by running the code or tests. Keep answers brief and factual.
 
 
+Use the read tool — not shell commands like cat — to inspect text files. Results include line numbers. Use offset and limit to continue reading large files.
+
+Use the write tool to create files or completely replace file contents. Existing files are overwritten, so read an existing file first (the default fs-policy requires it) and prefer edit for targeted changes.
+
+Use the edit tool for targeted changes to existing UTF-8 text files. It replaces literal old_string with new_string; by default old_string must appear exactly once. If old_string appears multiple times, provide a more specific old_string or set replace_all to true. Read the file first (the default fs-policy requires it), unless you just created or edited it in this session.
+
 Check the [exit code: N] marker on every bash result; investigate failures before moving on.
 
 Approval prompts are disabled in this session: actions that require approval are rejected automatically — do not request sandbox escalation (do not set `sandbox_permissions`).

examples/acp-agent/tests/snapshots/workspace-edit/session.jsonl

@@ -79,7 +79,7 @@
 {"type":"assistant/chunk","seq":77,"time":1783352265489,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":78,"time":1783352265491,"data":{"turn":1,"step":1,"content":[{"type":"reasoning","text":"The user wants me to:\n1. Read the file greeting.txt\n2. Append the word WORLD as a second line\n3. Read the file back with cat to confirm\n4. Reply with DONE\n\nLet me start by reading the file to see its contents."},{"type":"tool-call","id":"call_00_OjRFB4zvxu6UALDjytZD0978","name":"read","arguments":"{\"file_path\": \"greeting.txt\"}"}],"usage":{"inputTokens":2918,"outputTokens":101,"cacheReadTokens":0,"reasoningTokens":55}},"sourceEventSeqs":[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77],"surfaceOp":"append"}
 {"type":"tool/call","seq":79,"time":1783352265491,"data":{"turn":1,"step":1,"callId":"call_00_OjRFB4zvxu6UALDjytZD0978","name":"read","arguments":"{\"file_path\": \"greeting.txt\"}"}}
-{"type":"tool/result","seq":80,"time":1783352265504,"data":{"turn":1,"step":1,"callId":"call_00_OjRFB4zvxu6UALDjytZD0978","content":[{"type":"text","text":"Error: unknown tool \"read\""}],"isError":true,"error":{"name":"ToolNotFoundError","code":"UNKNOWN_TOOL"}},"sourceEventSeqs":[79],"surfaceOp":"append"}
+{"type":"tool/result","seq":80,"time":1783352265504,"data":{"turn":1,"step":1,"callId":"call_00_OjRFB4zvxu6UALDjytZD0978","content":[{"type":"text","text":"<path>/tmp/acp-snap-cwd-rxbEpP/greeting.txt</path>\n<type>file</type>\n<content>\n1: hello\n\n(End of file - total 1 lines)\n</content>"}],"isError":false},"sourceEventSeqs":[79],"surfaceOp":"append"}
 {"type":"step/end","seq":81,"time":1783352265504,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":82,"time":1783352265505,"data":{"turn":1,"step":2}}
 {"type":"assistant/chunk","seq":83,"time":1783352266385,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}

examples/acp-agent/tests/snapshots/workspace-edit/stdout.golden.jsonl

@@ -55,8 +55,8 @@
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" its"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" contents"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"."}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_OjRFB4zvxu6UALDjytZD0978","title":"read","kind":"other","status":"in_progress","rawInput":{"file_path":"greeting.txt"}}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_OjRFB4zvxu6UALDjytZD0978","status":"failed","content":[{"type":"content","content":{"type":"text","text":"Error: unknown tool \"read\""}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_00_OjRFB4zvxu6UALDjytZD0978","title":"Read greeting.txt","kind":"read","status":"in_progress","locations":[{"path":"greeting.txt","line":1}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_00_OjRFB4zvxu6UALDjytZD0978","status":"completed","content":[{"type":"content","content":{"type":"text","text":"<path>{{cwd}}/greeting.txt</path>\n<type>file</type>\n<content>\n1: hello\n\n(End of file - total 1 lines)\n</content>"}}]}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":"The"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" file"}}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_thought_chunk","content":{"type":"text","text":" contains"}}}}

packages/bash/bash-sandbox/package.json

@@ -25,16 +25,15 @@
     "@deepseek-ai/dsh-bash": "^0.0.1",
     "@deepseek-ai/dsh-bash-local": "^0.0.1",
     "@deepseek-ai/dsh-sandbox": "^0.0.1",
+    "@deepseek-ai/dsh-sandbox-policy": "^0.0.1",
     "cordis": "^4.0.0-rc.6"
   },
-  "dependencies": {
-    "schemastery": "^3.18.0"
-  },
   "devDependencies": {
     "@deepseek-ai/dsh-bash": "workspace:^",
     "@deepseek-ai/dsh-bash-local": "workspace:^",
     "@deepseek-ai/dsh-sandbox": "workspace:^",
     "@deepseek-ai/dsh-sandbox-local": "workspace:^",
+    "@deepseek-ai/dsh-sandbox-policy": "workspace:^",
     "node-addon-landlock-run": "0.0.0-test.0",
     "cordis": "^4.0.0-rc.6"
   }

packages/bash/bash-sandbox/src/index.ts

@@ -41,31 +41,23 @@
  * @module @deepseek-ai/dsh-bash-sandbox
  */
 
-import { resolve } from 'node:path'
 import { Context } from 'cordis'
-import z from 'schemastery'
 import type { BashExecRequest, BashExecSpec, BashRunResult, BashTask, BashTaskId } from '@deepseek-ai/dsh-bash'
 import { SandboxUnavailableError } from '@deepseek-ai/dsh-sandbox'
 import type { ConfinedSandboxMode, SandboxEnforcement, SandboxMode } from '@deepseek-ai/dsh-sandbox'
+import type {} from '@deepseek-ai/dsh-sandbox-policy'
 import { LocalBashExecutor } from '@deepseek-ai/dsh-bash-local'
 import type { Config as LocalConfig } from '@deepseek-ai/dsh-bash-local'
 
 /**
- * Plugin config: the local executor's knobs plus the sandbox policy. All
- * optional — `static Config` supplies the defaults (`mode: 'read-only'` is the
- * fail-safe default; an example that wants a workspace-writable agent opts in
- * explicitly). The runner choice is NOT configured here: which platform
- * backend confines the command is the `ctx.sandbox` provider's config.
+ * Plugin config: the local executor's knobs, verbatim. The sandbox policy —
+ * the default mode and the `workspace-write` boundary root — is NOT here: it
+ * lives on `ctx.sandboxPolicy` (`@deepseek-ai/dsh-sandbox-policy`), the one
+ * home both enforcing families read, so bash and fs can never confine to
+ * different roots. The runner choice is likewise the `ctx.sandbox` provider's
+ * config, not this executor's.
  */
-export interface Config extends LocalConfig {
-  /** File-sandbox mode commands run under (default: `read-only`). */
-  mode?: SandboxMode
-  /**
-   * Root directory `workspace-write` mode may write under (default: the
-   * executor's default working directory — `cwd`, else `process.cwd()`).
-   */
-  workspaceRoot?: string
-}
+export type Config = LocalConfig
 
 /**
  * Quote one string as a single-quoted POSIX shell word (embedded single
@@ -141,24 +133,18 @@ function matchesSignature(exitCode: number | null, stderr: string, signatures: r
  * INSTEAD OF `dsh-bash-local`, together with a `ctx.sandbox` provider, is
  * the whole swap — the tool layer is untouched). Its configured mode is the
  * fallback exposed by {@link sandboxMode}; `dsh-tool-bash` folds a session's
- * durable `bash/sandbox-mode` override and stamps the effective mode onto each
+ * durable `sandbox/mode` override and stamps the effective mode onto each
  * request, while an approved escalation may stamp a strictly wider mode for
  * one call. The tool's per-agent prompt section states that same effective
  * mode, and each run's `result.sandbox` reports what actually executed plus
  * enforcement completeness.
  */
 export class SandboxBashExecutor extends LocalBashExecutor {
-  static inject = ['sandbox']
+  static inject = ['sandbox', 'sandboxPolicy']
 
-  // The sandbox-specific fields intersect the local executor's Config as an
-  // inline schema call: the config catalog walks `static Config` statically.
-  static override Config: z<Config> = z.intersect([
-    LocalBashExecutor.Config,
-    z.object({
-      mode: z.union(['read-only', 'workspace-write', 'danger-full-access'] as const).default('read-only'),
-      workspaceRoot: z.string(),
-    }),
-  ])
+  // No own Config: the sandbox default (mode + workspaceRoot) moved to
+  // ctx.sandboxPolicy, so this executor inherits LocalBashExecutor's Config
+  // verbatim (the config catalog walks the inherited static).
 
   private readonly mode: SandboxMode
   private readonly workspaceRoot: string
@@ -182,12 +168,11 @@ export class SandboxBashExecutor extends LocalBashExecutor {
 
   constructor(ctx: Context, config: Config) {
     super(ctx, config)
-    // schemastery (static Config) already filled the defaulted fields — the
-    // cast records that runtime fact (mirrors LocalBashExecutor's config
-    // cast). `workspaceRoot` and `cwd` have NO schema default, so their
-    // fallback chain is real branching.
-    this.mode = config.mode as SandboxMode
-    this.workspaceRoot = resolve(config.workspaceRoot ?? config.cwd ?? process.cwd())
+    // The sandbox default (mode + workspaceRoot) is the one shared policy home
+    // both enforcing families read; injecting sandboxPolicy guarantees it is
+    // constructed first. workspaceRoot arrives already resolved absolute.
+    this.mode = ctx.sandboxPolicy.defaultMode
+    this.workspaceRoot = ctx.sandboxPolicy.workspaceRoot
   }
 
   /** The configured default mode — the capability fact the tool layer reads. */

packages/bash/bash-sandbox/tests/bwrap.e2e.ts

@@ -6,6 +6,7 @@ import { join } from 'node:path'
 import { afterEach, describe, expect, it } from 'vitest'
 import { Context } from 'cordis'
 import { bwrapProfileArgs, LocalSandboxProvider } from '@deepseek-ai/dsh-sandbox-local'
+import { SandboxPolicyService } from '@deepseek-ai/dsh-sandbox-policy'
 import { SandboxBashExecutor } from '@deepseek-ai/dsh-bash-sandbox'
 
 /**
@@ -46,7 +47,8 @@ async function tempDir(base: string): Promise<string> {
 async function sandboxedBash(workspace: string, mode: 'read-only' | 'workspace-write'): Promise<SandboxBashExecutor> {
   ctx = new Context()
   await ctx.plugin(LocalSandboxProvider, {})
-  await ctx.plugin(SandboxBashExecutor, { mode, cwd: workspace, workspaceRoot: workspace, timeoutMs: 30_000 })
+  await ctx.plugin(SandboxPolicyService, { mode, workspaceRoot: workspace })
+  await ctx.plugin(SandboxBashExecutor, { cwd: workspace, timeoutMs: 30_000 })
   return ctx.bash as SandboxBashExecutor
 }
 

packages/bash/bash-sandbox/tests/landlock.e2e.ts

@@ -7,6 +7,7 @@ import { afterEach, describe, expect, it } from 'vitest'
 import { Context } from 'cordis'
 import { launcherPath } from 'node-addon-landlock-run'
 import { LocalSandboxProvider } from '@deepseek-ai/dsh-sandbox-local'
+import { SandboxPolicyService } from '@deepseek-ai/dsh-sandbox-policy'
 import { SandboxBashExecutor } from '@deepseek-ai/dsh-bash-sandbox'
 
 /**
@@ -45,7 +46,8 @@ async function sandboxedBash(workspace: string, mode: 'read-only' | 'workspace-w
   ctx = new Context()
   await ctx.plugin(LocalSandboxProvider, {})
   ;(ctx.sandbox as LocalSandboxProvider).internals = { probeBwrap: () => false }
-  await ctx.plugin(SandboxBashExecutor, { mode, cwd: workspace, workspaceRoot: workspace, timeoutMs: 30_000 })
+  await ctx.plugin(SandboxPolicyService, { mode, workspaceRoot: workspace })
+  await ctx.plugin(SandboxBashExecutor, { cwd: workspace, timeoutMs: 30_000 })
   return ctx.bash as SandboxBashExecutor
 }
 

packages/bash/bash-sandbox/tests/sandbox.spec.ts

@@ -15,7 +15,8 @@ import { describe, expect, it, vi } from 'vitest'
 import { Context } from 'cordis'
 import type { BashRunResult, CollectedOutput } from '@deepseek-ai/dsh-bash'
 import { SANDBOX_UNAVAILABLE, SandboxProvider, SandboxUnavailableError } from '@deepseek-ai/dsh-sandbox'
-import type { ConfinedArgv, SandboxPolicy } from '@deepseek-ai/dsh-sandbox'
+import type { ConfinedArgv, SandboxMode, SandboxPolicy } from '@deepseek-ai/dsh-sandbox'
+import { SandboxPolicyService } from '@deepseek-ai/dsh-sandbox-policy'
 import { classifyDenial, classifyRunnerFailure, SandboxBashExecutor, shellQuote } from '@deepseek-ai/dsh-bash-sandbox'
 import type { Config } from '@deepseek-ai/dsh-bash-sandbox'
 
@@ -39,9 +40,15 @@ const passthrough = (argv: readonly string[]): ConfinedArgv =>
 
 /**
  * Boot a context with a recording fake `ctx.sandbox` (behavior injectable
- * per test) and the executor under test on top of it.
+ * per test), the shared `ctx.sandboxPolicy` (mode + workspaceRoot), and the
+ * executor under test on top of them. `mode`/`workspaceRoot` route to the
+ * policy service; the rest (cwd, graceMs, timeoutMs) to the executor.
  */
-async function setup(config: Config = {}, behavior: (argv: readonly string[], policy: SandboxPolicy) => ConfinedArgv = passthrough) {
+async function setup(
+  config: { mode?: SandboxMode; workspaceRoot?: string } & Config = {},
+  behavior: (argv: readonly string[], policy: SandboxPolicy) => ConfinedArgv = passthrough,
+) {
+  const { mode, workspaceRoot, ...execConfig } = config
   const calls: ConfineCall[] = []
   class FakeSandboxProvider extends SandboxProvider {
     confine(argv: readonly string[], policy: SandboxPolicy): ConfinedArgv {
@@ -51,7 +58,11 @@ async function setup(config: Config = {}, behavior: (argv: readonly string[], po
   }
   const ctx = new Context()
   await ctx.plugin(FakeSandboxProvider)
-  await ctx.plugin(SandboxBashExecutor, { graceMs: 200, ...config })
+  await ctx.plugin(SandboxPolicyService, {
+    ...mode !== undefined ? { mode } : {},
+    ...workspaceRoot !== undefined ? { workspaceRoot } : {},
+  })
+  await ctx.plugin(SandboxBashExecutor, { graceMs: 200, ...execConfig })
   const bash = ctx.bash as SandboxBashExecutor
   bash.internals = { spillDir }
   return { ctx, bash, calls }
@@ -86,14 +97,14 @@ describe('the provider hand-off', () => {
     expect(result.sandbox).toEqual({ mode: 'read-only', denied: false, enforcement: 'full' })
   })
 
-  it('workspace-write rides the policy, workspaceRoot falling back to cwd when not configured', async () => {
-    const { bash, calls } = await setup({ mode: 'workspace-write', cwd: tmpdir() })
+  it('workspace-write rides the policy, workspaceRoot falling back to process.cwd() when not configured', async () => {
+    const { bash, calls } = await setup({ mode: 'workspace-write' })
     const result = await bash.run(bash.resolve({ command: 'true' }))
     expect(result.sandbox).toEqual({ mode: 'workspace-write', denied: false, enforcement: 'full' })
-    expect(calls[0]?.policy).toEqual({ mode: 'workspace-write', workspaceRoot: resolve(tmpdir()) })
+    expect(calls[0]?.policy).toEqual({ mode: 'workspace-write', workspaceRoot: resolve(process.cwd()) })
   })
 
-  it('an explicit workspaceRoot wins over cwd', async () => {
+  it('an explicit workspaceRoot on the policy wins', async () => {
     const { calls, bash } = await setup({ mode: 'workspace-write', workspaceRoot: '/ws', cwd: tmpdir() })
     await bash.run(bash.resolve({ command: 'true' }))
     expect(calls[0]?.policy.workspaceRoot).toBe(resolve('/ws'))

packages/bash/bash-sandbox/tests/seatbelt.e2e.ts

@@ -6,6 +6,7 @@ import { join } from 'node:path'
 import { afterEach, describe, expect, it } from 'vitest'
 import { Context } from 'cordis'
 import { LocalSandboxProvider, seatbeltProfileArgs } from '@deepseek-ai/dsh-sandbox-local'
+import { SandboxPolicyService } from '@deepseek-ai/dsh-sandbox-policy'
 import { SandboxBashExecutor } from '@deepseek-ai/dsh-bash-sandbox'
 
 /**
@@ -43,7 +44,8 @@ async function sandboxedBash(workspace: string, mode: 'read-only' | 'workspace-w
   ctx = new Context()
   await ctx.plugin(LocalSandboxProvider, {})
   ;(ctx.sandbox as LocalSandboxProvider).internals = { probeBwrap: () => false, probeLandlock: () => 'unusable' }
-  await ctx.plugin(SandboxBashExecutor, { mode, cwd: workspace, workspaceRoot: workspace, timeoutMs: 30_000 })
+  await ctx.plugin(SandboxPolicyService, { mode, workspaceRoot: workspace })
+  await ctx.plugin(SandboxBashExecutor, { cwd: workspace, timeoutMs: 30_000 })
   return ctx.bash as SandboxBashExecutor
 }
 

packages/bash/bash-sandbox/tsconfig.json

@@ -14,9 +14,6 @@
     {
       "path": "../../../vendor/cordis"
     },
-    {
-      "path": "../../../vendor/schemastery"
-    },
     {
       "path": "../../util/brand"
     },
@@ -26,6 +23,9 @@
     {
       "path": "../../sandbox/sandbox"
     },
+    {
+      "path": "../../sandbox/sandbox-policy"
+    },
     {
       "path": "../../bash/bash"
     },

packages/bash/bash/package.json

@@ -24,13 +24,11 @@
   "peerDependencies": {
     "@deepseek-ai/dsh-brand": "^0.0.1",
     "@deepseek-ai/dsh-sandbox": "^0.0.1",
-    "@deepseek-ai/dsh-session": "^0.0.1",
     "cordis": "^4.0.0-rc.6"
   },
   "devDependencies": {
     "@deepseek-ai/dsh-brand": "workspace:^",
     "@deepseek-ai/dsh-sandbox": "workspace:^",
-    "@deepseek-ai/dsh-session": "workspace:^",
     "cordis": "^4.0.0-rc.6"
   }
 }

packages/bash/bash/src/index.ts

@@ -19,7 +19,6 @@ import type { SandboxMode } from '@deepseek-ai/dsh-sandbox'
 import type { BashExecRequest, BashExecSpec, BashRunResult, BashTask, BashTaskId, BashTaskListener, BashTaskRead, OwnerToken } from './types.ts'
 
 export { BashTaskId, OwnerToken } from './types.ts'
-export { SANDBOX_MODES, effectiveSandboxMode, setSandboxMode } from './session-mode.ts'
 export type {
   BashExecRequest,
   BashExecSpec,

packages/bash/bash/src/types.ts

@@ -130,7 +130,7 @@ export interface BashExecRequest {
    * consumer sets it only from an explicit policy source — an
    * `'allowed-once'` grant a human just issued through `ctx.approval` (the
    * escalation flow in the sandbox RFC § Escalation, which outranks), or the
-   * session's standing override folded from its own `bash/sandbox-mode`
+   * session's standing override folded from its own `sandbox/mode`
    * events (the sandbox RFC § Per-session mode switching — the user's recorded per-session
    * choice). A sandboxing executor confines THIS call under the given mode;
    * a non-sandboxing executor carries the field and confines nothing (the

packages/bash/bash/tsconfig.json

@@ -19,9 +19,6 @@
     },
     {
       "path": "../../sandbox/sandbox"
-    },
-    {
-      "path": "../../core/session"
     }
   ]
 }

packages/bash/tool-bash/package.json

@@ -25,8 +25,8 @@
     "@deepseek-ai/dsh-agent": "^0.0.1",
     "@deepseek-ai/dsh-user-approval": "^0.0.1",
     "@deepseek-ai/dsh-bash": "^0.0.1",
-    "@deepseek-ai/dsh-llm": "^0.0.1",
     "@deepseek-ai/dsh-sandbox": "^0.0.1",
+    "@deepseek-ai/dsh-sandbox-policy": "^0.0.1",
     "@deepseek-ai/dsh-system-prompt": "^0.0.1",
     "@deepseek-ai/dsh-tools": "^0.0.1",
     "cordis": "^4.0.0-rc.6"
@@ -41,6 +41,7 @@
     "@deepseek-ai/dsh-llm": "workspace:^",
     "@deepseek-ai/dsh-sandbox": "workspace:^",
     "@deepseek-ai/dsh-sandbox-local": "workspace:^",
+    "@deepseek-ai/dsh-sandbox-policy": "workspace:^",
     "@deepseek-ai/dsh-session": "workspace:^",
     "@deepseek-ai/dsh-system-prompt": "workspace:^",
     "@deepseek-ai/dsh-tools": "workspace:^",

packages/bash/tool-bash/src/index.ts

@@ -44,7 +44,7 @@
  * that the composition cannot honor.
  *
  * Per-session mode switching (the sandbox RFC § Per-session mode switching): a session may carry a
- * standing sandbox-mode override — the `bash/sandbox-mode` event fold from
+ * standing sandbox-mode override — the `sandbox/mode` event fold from
  * `@deepseek-ai/dsh-bash` — which this plugin makes real at EXECUTION: each
  * call is stamped `escalation grant > session override > executor default`.
  * The prompt deliberately does NOT state the mode and no switch is narrated:
@@ -60,14 +60,21 @@ import { isAbsolute, resolve as resolvePath } from 'node:path'
 import { defineTool } from '@deepseek-ai/dsh-tools'
 import type { GenericCallView, TerminalCallView, ToolExecution, ToolResult, ToolResultView } from '@deepseek-ai/dsh-tools'
 import type { Agent } from '@deepseek-ai/dsh-agent'
-import { assertNever } from '@deepseek-ai/dsh-llm'
 import type {} from '@deepseek-ai/dsh-system-prompt'
 // Side-effect type import: declaration-merges `ctx.approval`, consumed
 // opportunistically by the escalation gate (`ctx.get('approval')` — the seam
 // stays optional at runtime, same pattern as dsh-tools' ask routing).
 import type {} from '@deepseek-ai/dsh-user-approval'
 import type { SandboxMode } from '@deepseek-ai/dsh-sandbox'
-import { BashTaskId, OwnerToken, effectiveSandboxMode } from '@deepseek-ai/dsh-bash'
+import {
+  ESCALATION_TARGETS,
+  approveEscalation,
+  escalationHintMarker,
+  sandboxDenialMarker,
+  validateEscalationArgs,
+} from '@deepseek-ai/dsh-sandbox'
+import { effectiveSandboxMode } from '@deepseek-ai/dsh-sandbox-policy'
+import { BashTaskId, OwnerToken } from '@deepseek-ai/dsh-bash'
 import type { BashRunResult, BashTask, CollectedOutput } from '@deepseek-ai/dsh-bash'
 
 export const name = 'tool-bash'
@@ -93,15 +100,9 @@ function validateBashArgs(args: BashToolArgs): void {
   if (args.timeoutMs !== undefined && (!Number.isFinite(args.timeoutMs) || args.timeoutMs <= 0)) {
     throw new Error(`invalid timeoutMs: expected a positive number, got ${JSON.stringify(args.timeoutMs)}`)
   }
-  if (args.sandbox_permissions !== undefined && args.justification === undefined) {
-    throw new Error('invalid escalation: sandbox_permissions requires a justification')
-  }
-  if (args.justification !== undefined && args.sandbox_permissions === undefined) {
-    throw new Error('invalid escalation: justification is only valid together with sandbox_permissions')
-  }
-  if (args.justification !== undefined && args.justification.trim().length === 0) {
-    throw new Error('invalid justification: expected a non-empty sentence')
-  }
+  // The escalation pairing (sandbox_permissions ⇔ justification, non-empty) is
+  // the shared rule both enforcing families validate identically.
+  validateEscalationArgs(args.sandbox_permissions, args.justification)
 }
 
 /**
@@ -132,27 +133,6 @@ interface BashToolArgs {
   justification?: string
 }
 
-/**
- * The strictly-wider table: what a call whose effective mode is the key may
- * escalate TO. Checked at EXECUTION, never baked into the schema — the
- * schema's enum is {@link ESCALATION_TARGETS}, because schemas are
- * registry-global while the effective mode is per-call truth.
- */
-const WIDER_MODES: Record<string, readonly SandboxMode[]> = {
-  'read-only': ['workspace-write', 'danger-full-access'],
-  'workspace-write': ['danger-full-access'],
-}
-
-/**
- * The closed escalation-target vocabulary — every mode a call could ever
- * escalate TO (`read-only` is the floor; nothing escalates to it). Advertised
- * whenever the mounted executor confines: cutting the enum down to the modes
- * wider than the executor's DEFAULT would strand a session whose effective
- * mode sits below it (a `danger-full-access` default would advertise nothing
- * while a narrower-switched session stays confined with no lever).
- */
-const ESCALATION_TARGETS: readonly SandboxMode[] = ['workspace-write', 'danger-full-access']
-
 /**
  * The bash tool's static description. The base text is byte-stable regardless
  * of composition (it is part of the pinned snapshot header); the escalation
@@ -222,13 +202,13 @@ export function renderResult(
   // stays the LAST line (exitStatus() anchors its parse there). Denial is a
   // reported fact like timeout: the model decides how to react.
   if (result.sandbox?.denied) {
-    markers.push(`[sandbox: file access denied under ${result.sandbox.mode} mode]`)
+    markers.push(sandboxDenialMarker(result.sandbox.mode))
     // The same-turn nudge lives at the decision point: only when this
     // composition advertises the fields (a lever is never hinted that the
     // schema does not offer), and inside the sandbox marker family so the
     // exit-code marker stays the last line.
     if (escalationModes.length > 0) {
-      markers.push('[sandbox: escalation available — retry this exact command once with sandbox_permissions (the narrowest wider mode that suffices) + justification; the approval prompt asks the user]')
+      markers.push(escalationHintMarker('command'))
     }
   }
   // Timeout is reported independently of how the process actually ended: a
@@ -482,7 +462,7 @@ export function apply(ctx: Context): void {
 
   /**
    * The session's standing mode override for an ordinary (non-escalating)
-   * call: the `bash/sandbox-mode` fold of the calling agent's log, stamped
+   * call: the `sandbox/mode` fold of the calling agent's log, stamped
    * onto the request so EXECUTION follows the same effective mode the prompt
    * section states. Weakest precedence — an escalation grant (freshly
    * approved for exactly this call) outranks it, and without either the
@@ -495,58 +475,30 @@ export function apply(ctx: Context): void {
 
   /**
    * Resolve a sandbox-escalation request through `ctx.approval` BEFORE
-   * anything executes. Returns the granted mode to stamp onto the bash
-   * request; throws the distinct fail-closed text for every other path (no
-   * service composed, an agent-less execution, a rejection, a cancellation,
-   * an unanswerable ask) — the registry turns the throw into this call's
-   * isError result, and nothing has run. The seam is consumed
-   * opportunistically (`ctx.get`, the dsh-tools ask-routing pattern), so a
-   * deployment without it degrades per call, never at registration.
+   * anything executes, delegating the shared fail-closed sequence (strict
+   * widening, channel resolution, outcome mapping) to
+   * {@link approveEscalation}. This tool contributes only the composition
+   * guard (the fields are unadvertised without a sandboxing executor, yet
+   * schema validation checks advertised keys only, so an unadvertised
+   * `sandbox_permissions` still reaches execute) and the channel closure over
+   * `ctx.approval` — consumed opportunistically (`ctx.get`, the dsh-tools
+   * ask-routing pattern) so a deployment without it degrades per call.
    */
-  const approveEscalation = async (mode: string, justification: string, exec: ToolExecution): Promise<SandboxMode> => {
-    // Schema validation only checks ADVERTISED keys, so an unadvertised
-    // `sandbox_permissions` (no sandboxing executor) still reaches execute — reject it here so a
-    // human is never prompted to "escalate" a sandbox that is not there. When
-    // the fields ARE advertised, the registry's SchemaSpec enum has already
-    // pinned `mode` to this ladder for every caller.
+  const approveBashEscalation = (mode: string, justification: string, exec: ToolExecution): Promise<SandboxMode> => {
     if (escalationModes.length === 0) {
       throw new Error('sandbox_permissions is not available in this composition (no sandboxing executor to escalate)')
     }
-    // Strict widening is an EXECUTION check against the call's effective
-    // mode — session override ?? executor default, the same fold ordinary
-    // calls are stamped with — deliberately not a schema constraint (the
-    // enum is the closed target vocabulary; the effective mode is per-call
-    // truth). A non-widening request fails closed here and never prompts a
-    // human.
     const effectiveMode = (sessionOverride(exec) ?? defaultMode) as SandboxMode
-    if (!(WIDER_MODES[effectiveMode] ?? []).includes(mode as SandboxMode)) {
-      throw new Error(`sandbox escalation to "${mode}" is not strictly wider than this call's current "${effectiveMode}" mode`)
-    }
-    const approval = ctx.get('approval')
-    if (approval === undefined) {
-      throw new Error(`sandbox escalation to "${mode}" requires approval, but no approval service is composed`)
-    }
-    if (exec.agent === undefined) {
-      throw new Error(`sandbox escalation to "${mode}" requires approval, but the call has no agent to route it through`)
-    }
-    const outcome = await approval.request({
-      agent: exec.agent,
-      toolName: 'bash',
-      callId: exec.callId,
-      // Self-contained for the audit trail: approval/asked stores this
-      // reason, and the target mode is part of the grant's identity.
-      reason: `escalate sandbox to ${mode}: ${justification}`,
-      ...exec.signal ? { signal: exec.signal } : {},
-    })
-    switch (outcome) {
-      // The SchemaSpec enum already pinned `mode` to the closed target
-      // vocabulary; the per-call check above proved it is strictly wider.
-      case 'allowed-once': return mode as SandboxMode
-      case 'rejected': throw new Error(`the user rejected escalating this command to "${mode}"`)
-      case 'cancelled': throw new Error(`approval for escalating to "${mode}" was cancelled`)
-      case 'unavailable': throw new Error(`sandbox escalation to "${mode}" requires approval, but no approval channel is available`)
-      default: return assertNever(outcome, 'ApprovalOutcome')
-    }
+    return approveEscalation(
+      { requestedMode: mode, justification, effectiveMode, subject: 'command' },
+      {
+        approver: ctx.get('approval'),
+        agent: exec.agent,
+        callId: exec.callId,
+        toolName: 'bash',
+        ...exec.signal ? { signal: exec.signal } : {},
+      },
+    )
   }
 
   ctx.tools.register(defineTool({
@@ -589,7 +541,7 @@ export function apply(ctx: Context): void {
       // An ordinary call carries the session's standing override instead —
       // grant > session override > executor default (see sessionOverride).
       const sandboxMode = args.sandbox_permissions !== undefined && args.justification !== undefined
-        ? await approveEscalation(args.sandbox_permissions, args.justification, exec)
+        ? await approveBashEscalation(args.sandbox_permissions, args.justification, exec)
         : sessionOverride(exec)
       // Default the workdir to the calling agent's session cwd so each ACP
       // session runs in its own workspace (see resolveWorkdir); an explicit
@@ -649,9 +601,9 @@ export function apply(ctx: Context): void {
         // hint). Background denials are only classifiable once the task
         // settles (the classifier needs the whole stderr), so the marker
         // rides every read that sees the settled task.
-        text += `\n[sandbox: file access denied under ${read.task.sandbox.mode} mode]`
+        text += `\n${sandboxDenialMarker(read.task.sandbox.mode)}`
         if (escalationModes.length > 0) {
-          text += '\n[sandbox: escalation available — retry this exact command once with sandbox_permissions (the narrowest wider mode that suffices) + justification; the approval prompt asks the user]'
+          text += `\n${escalationHintMarker('command')}`
         }
       }
       return Promise.resolve([{ type: 'text', text }])

packages/bash/tool-bash/tests/tools.spec.ts

@@ -4,7 +4,7 @@ import { join } from 'node:path'
 import { describe, expect, it, vi } from 'vitest'
 import { Context } from 'cordis'
 import { CallId } from '@deepseek-ai/dsh-llm'
-import { BashExecutor, BashTaskId, setSandboxMode } from '@deepseek-ai/dsh-bash'
+import { BashExecutor, BashTaskId } from '@deepseek-ai/dsh-bash'
 import type { BashExecRequest, BashExecSpec, BashRunResult, BashTask, BashTaskRead, OwnerToken } from '@deepseek-ai/dsh-bash'
 import { Session, SessionId } from '@deepseek-ai/dsh-session'
 import SystemPrompt from '@deepseek-ai/dsh-system-prompt'
@@ -15,6 +15,7 @@ import { LocalBashExecutor } from '@deepseek-ai/dsh-bash-local'
 import { SandboxBashExecutor } from '@deepseek-ai/dsh-bash-sandbox'
 import { SandboxProvider } from '@deepseek-ai/dsh-sandbox'
 import type { ConfinedArgv } from '@deepseek-ai/dsh-sandbox'
+import { SandboxPolicyService, setSandboxMode } from '@deepseek-ai/dsh-sandbox-policy'
 import { LocalSandboxProvider } from '@deepseek-ai/dsh-sandbox-local'
 import ApprovalService from '@deepseek-ai/dsh-user-approval'
 import type { ApprovalOutcome } from '@deepseek-ai/dsh-user-approval'
@@ -1040,6 +1041,7 @@ describe('sandbox rendering', () => {
     await ctx.plugin(ToolRegistry)
     await ctx.plugin(AgentRegistry)
     await ctx.plugin(LocalSandboxProvider, PASSTHROUGH_RUNNER_CONFIG)
+    await ctx.plugin(SandboxPolicyService, {})
     await ctx.plugin(SandboxBashExecutor, { graceMs: 200 })
     const bash = ctx.bash as SandboxBashExecutor
     bash.internals = { spillDir }
@@ -1106,6 +1108,7 @@ describe('sandbox rendering', () => {
     await ctx.plugin(ToolRegistry)
     await ctx.plugin(AgentRegistry)
     await ctx.plugin(FakeProvider)
+    await ctx.plugin(SandboxPolicyService, {})
     await ctx.plugin(SandboxBashExecutor, { graceMs: 200 })
     const bash = ctx.bash as SandboxBashExecutor
     bash.internals = { spillDir }
@@ -1126,6 +1129,7 @@ describe('sandbox rendering', () => {
       runnerCommand: ['bash', '-c', `printf '${signature}\\n' >&2; exit 125`, 'custom-runner'],
       runnerFailureSignatures: [signature],
     })
+    await ctx.plugin(SandboxPolicyService, {})
     await ctx.plugin(SandboxBashExecutor, { graceMs: 200 })
     const bash = ctx.bash as SandboxBashExecutor
     bash.internals = { spillDir }
@@ -1144,6 +1148,7 @@ describe('sandbox rendering', () => {
     await ctx.plugin(ToolRegistry)
     await ctx.plugin(AgentRegistry)
     await ctx.plugin(LocalSandboxProvider, PASSTHROUGH_RUNNER_CONFIG)
+    await ctx.plugin(SandboxPolicyService, {})
     await ctx.plugin(SandboxBashExecutor, { graceMs: 200 })
     const bash = ctx.bash as SandboxBashExecutor
     bash.internals = { spillDir }
@@ -1167,7 +1172,8 @@ describe('sandbox escalation (sandbox_permissions / justification)', () => {
     await ctx.plugin(ToolRegistry)
     await ctx.plugin(AgentRegistry)
     await ctx.plugin(LocalSandboxProvider, PASSTHROUGH_RUNNER_CONFIG)
-    await ctx.plugin(SandboxBashExecutor, { graceMs: 200, ...mode !== undefined ? { mode } : {} })
+    await ctx.plugin(SandboxPolicyService, mode !== undefined ? { mode } : {})
+    await ctx.plugin(SandboxBashExecutor, { graceMs: 200 })
     const bash = ctx.bash as SandboxBashExecutor
     bash.internals = { spillDir }
     if (opts.approval === true) await ctx.plugin(ApprovalService, opts.policy !== undefined ? { policy: opts.policy } : {})
@@ -1381,7 +1387,7 @@ describe('sandbox escalation (sandbox_permissions / justification)', () => {
   })
 })
 
-describe('per-session sandbox mode (the bash/sandbox-mode fold)', () => {
+describe('per-session sandbox mode (the sandbox/mode fold)', () => {
   /** Compose the real sandbox stack (passthrough runner) at a given default mode. */
   async function setupModal(mode: 'read-only' | 'workspace-write' | 'danger-full-access' = 'read-only', opts: { approval?: boolean } = {}) {
     const ctx = new Context()
@@ -1389,7 +1395,8 @@ describe('per-session sandbox mode (the bash/sandbox-mode fold)', () => {
     await ctx.plugin(ToolRegistry)
     await ctx.plugin(AgentRegistry)
     await ctx.plugin(LocalSandboxProvider, PASSTHROUGH_RUNNER_CONFIG)
-    await ctx.plugin(SandboxBashExecutor, { graceMs: 200, mode })
+    await ctx.plugin(SandboxPolicyService, { mode })
+    await ctx.plugin(SandboxBashExecutor, { graceMs: 200 })
     ;(ctx.bash as SandboxBashExecutor).internals = { spillDir }
     if (opts.approval === true) await ctx.plugin(ApprovalService)
     await ctx.plugin(ToolBash)

packages/bash/tool-bash/tsconfig.json

@@ -14,9 +14,6 @@
     {
       "path": "../../../vendor/cordis"
     },
-    {
-      "path": "../../llm/llm"
-    },
     {
       "path": "../../core/tools"
     },
@@ -34,6 +31,9 @@
     },
     {
       "path": "../../sandbox/sandbox"
+    },
+    {
+      "path": "../../sandbox/sandbox-policy"
     }
   ]
 }

packages/cordis/tool-cordis/src/api-catalog.ts

@@ -121,8 +121,8 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
       'abstract readText(target: FsTarget, signal?: AbortSignal): Promise<string>',
       'abstract streamText(target: FsTarget, signal?: AbortSignal): Promise<AsyncIterable<string>>',
       'abstract listDir(target: FsTarget, signal?: AbortSignal): Promise<FsDirEntry[]>',
-      'abstract writeText(target: FsTarget, content: string, expected?: FsWriteIntent, signal?: AbortSignal): Promise<FsWriteOutcome>',
-      'abstract editText(target: FsTarget, edit: FsEditRequest, expected?: { version: FsVersion }, signal?: AbortSignal): Promise<FsEditOutcome>',
+      'abstract writeText( target: FsTarget, content: string, expected?: FsWriteIntent, signal?: AbortSignal, sandboxMode?: SandboxMode, ): Promise<FsWriteOutcome>',
+      'abstract editText( target: FsTarget, edit: FsEditRequest, expected?: { version: FsVersion }, signal?: AbortSignal, sandboxMode?: SandboxMode, ): Promise<FsEditOutcome>',
     ],
   },
   {
@@ -151,6 +151,11 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
       'abstract confine(argv: readonly string[], policy: SandboxPolicy): ConfinedArgv',
     ],
   },
+  {
+    key: 'sandboxPolicy',
+    summary: 'The sandbox-policy service (`ctx.sandboxPolicy`).',
+    methods: [],
+  },
   {
     key: 'sessionPersistence',
     summary: 'Abstract durable session-persistence service.',

packages/fs/README.md

@@ -6,10 +6,11 @@ The filesystem stack: a provider seam (text IO + atomic mutation with an optiona
 |---|---|---|
 | `fs/` | Provider seam: text IO + atomic mutation primitives (optional version guard); owns the `fs/*` policy events | `ctx.fs` |
 | `fs-local/` | Local-filesystem `FileSystem` implementation | (registers `ctx.fs`) |
+| `fs-sandbox/` | Sandbox-enforcing `FileSystem`: extends `fs-local` and fences write/edit by the per-call sandbox mode (read-only denies, workspace-write contains to the workspace + temp roots), reads pass through | (registers `ctx.fs`) |
 | `fs-policy/` | Policy gate plugin: observed-state + read-before-edit + version-guarded write/edit, via the `fs/*` event gate | (no service — `fs/*` listeners) |
-| `tool-fs/` | Model-facing `read`/`write`/`edit` tools AND the executor (reads via `ctx.fs`, owns read windowing, dispatches `fs/*`) | (registers on `ctx.tools`) |
+| `tool-fs/` | Model-facing `read`/`write`/`edit` tools AND the executor (reads via `ctx.fs`, owns read windowing, dispatches `fs/*`); advertises the sandbox escalation fields when the mounted `ctx.fs` confines | (registers on `ctx.tools`) |
 
-The interface lives at `fs/fs/`. A sandboxed, remote, or project-scoped filesystem backend can replace `fs-local` without touching the seam, the policy gate, or the model-facing tool schemas. The policy (`fs-policy/`) is a plugin that participates only through the `fs/*` event gate, not a service the tool injects — so dropping it gracefully loses the policy and leaves the unconstrained bare provider rather than breaking the tool. A deployment that loads `tool-fs/` is expected to also load it.
+The interface lives at `fs/fs/`. A sandboxed, remote, or project-scoped filesystem backend can replace `fs-local` without touching the seam, the policy gate, or the model-facing tool schemas — `fs-sandbox` is the first such replacement (an in-process path fence over the shared sandbox mode; see [the cross-family fs sandbox RFC](../../docs/rfc/implemented/feature/2026-07-14-cross-family-fs-sandbox.md)). The policy (`fs-policy/`) is a plugin that participates only through the `fs/*` event gate, not a service the tool injects — so dropping it gracefully loses the policy and leaves the unconstrained bare provider rather than breaking the tool. A deployment that loads `tool-fs/` is expected to also load it. The mode fence and the read-before-edit gate are orthogonal and compose.
 
 ## No timeouts on file IO
 

packages/fs/fs-sandbox/README.md

@@ -0,0 +1,19 @@
+# dsh-fs-sandbox — the sandbox-enforcing filesystem backend
+
+`SandboxedFileSystem` extends [`LocalFileSystem`](../fs-local/README.md) and registers as `ctx.fs`. It inherits every text-storage mechanic verbatim (resolve, stat, read/stream, list, the atomic write, the read-match-write edit critical section) and adds only a per-call MODE fence on `writeText`/`editText`. Reads always pass through — every mode permits reading.
+
+Loading it INSTEAD OF `dsh-fs-local`, together with a [`ctx.sandboxPolicy`](../../sandbox/sandbox-policy/README.md), is the whole swap; the model-facing tools (`dsh-tool-fs`) are untouched. Injects `sandboxPolicy` for the default mode and the `workspace-write` boundary root — the SAME policy home bash reads, so the two families never confine to different roots.
+
+## The fence
+
+The per-call mode is the tool-stamped effective mode (session override or escalation grant), falling back to the deployment default:
+
+- `read-only` — denies every mutation with the structured `FS_SANDBOX_DENIED`.
+- `workspace-write` — allows a mutation only when the target canonicalizes under a writable root: the workspace root plus the platform temp areas (`/tmp`, `os.tmpdir()`), the SAME set the Seatbelt profile grants, derived from the one [`writableRoots`](../../sandbox/README.md) function so the fs fence and the bash runner cannot drift. The target is re-canonicalized immediately before delegating, so an ancestor symlink swapped since the tool resolved it is caught.
+- `danger-full-access` — delegates unfenced.
+
+## Threat model: a policy fence, not a kernel boundary
+
+The fence is a check in TRUSTED code over a MODEL-CONTROLLED path — the operations are the seam's own (open, rename), only the target path is untrusted, so canonicalize-then-contain is the complete answer to this surface. This mirrors the `code-runtime` stance: containment, not a security boundary. Kernel-grade isolation of untrusted CODE stays `ctx.bash`'s job ([`dsh-bash-sandbox`](../../bash/bash-sandbox/README.md)). The residual TOCTOU (an ancestor symlink swapped between the containment re-check and the syscall) is narrowed by re-canonicalizing immediately before the write and is accepted for this threat model; a kernel-tight boundary needs `openat2`-class primitives not worth their portability cost here.
+
+A denial is a structured `FsError` (`FS_SANDBOX_DENIED`, carrying the effective mode) — no stderr text inference (unlike bash's kernel denials), because an in-process fence knows exactly what it refused. The model-facing `[sandbox: file access denied under <mode> mode]` marker and the one-approved-wider retry live in the tool layer (`dsh-tool-fs`), exactly as bash's do. See [the cross-family fs sandbox RFC](../../../docs/rfc/implemented/feature/2026-07-14-cross-family-fs-sandbox.md).

packages/fs/fs-sandbox/package.json

@@ -0,0 +1,38 @@
+{
+  "name": "@deepseek-ai/dsh-fs-sandbox",
+  "description": "Sandbox-enforcing implementation of the DeepSeek Harness filesystem seam: fences write/edit by the per-call sandbox mode (read-only denies mutation, workspace-write contains it to the workspace + temp roots) while reads pass through",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "main": "lib/index.js",
+  "types": "lib/types/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./lib/types/index.d.ts",
+      "default": "./lib/index.js"
+    },
+    "./src/*": "./src/*",
+    "./package.json": "./package.json"
+  },
+  "files": [
+    "lib/index.js",
+    "lib/types/**/*.d.ts",
+    "lib/types/**/*.d.ts.map",
+    "src"
+  ],
+  "license": "BSD-3-Clause",
+  "peerDependencies": {
+    "@deepseek-ai/dsh-fs": "^0.0.1",
+    "@deepseek-ai/dsh-fs-local": "^0.0.1",
+    "@deepseek-ai/dsh-sandbox": "^0.0.1",
+    "@deepseek-ai/dsh-sandbox-policy": "^0.0.1",
+    "cordis": "^4.0.0-rc.6"
+  },
+  "devDependencies": {
+    "@deepseek-ai/dsh-fs": "workspace:^",
+    "@deepseek-ai/dsh-fs-local": "workspace:^",
+    "@deepseek-ai/dsh-sandbox": "workspace:^",
+    "@deepseek-ai/dsh-sandbox-policy": "workspace:^",
+    "cordis": "^4.0.0-rc.6"
+  }
+}

packages/fs/fs-sandbox/src/index.ts

@@ -0,0 +1,155 @@
+/**
+ * `SandboxedFileSystem`: the sandbox-enforcing implementation of the
+ * `@deepseek-ai/dsh-fs` provider seam. It extends `LocalFileSystem` so all
+ * text-storage mechanics — resolve, stat, read/stream, list, the atomic
+ * write and the read-match-write edit critical section — are the local
+ * implementation's, verbatim; this package adds only the per-call MODE fence
+ * on the two mutations. Reads pass through untouched: every mode permits
+ * reading.
+ *
+ * The fence is a policy check in TRUSTED code over a MODEL-CONTROLLED path,
+ * NOT a kernel boundary — the operations are the seam's own (open, rename),
+ * and only the target path is untrusted, so canonicalize-then-contain is the
+ * complete answer to this surface. Kernel-grade isolation of untrusted CODE
+ * stays `ctx.bash`'s job (`@deepseek-ai/dsh-bash-sandbox`). This mirrors the
+ * `code-runtime` stance: containment, not a security boundary. The residual
+ * TOCTOU (an ancestor symlink swapped between the containment re-check and the
+ * syscall) is narrowed by re-canonicalizing immediately before delegating and
+ * is accepted for this threat model.
+ *
+ * Per-call mode: `read-only` denies every mutation; `workspace-write` allows a
+ * mutation only when the target canonicalizes under the workspace root or a
+ * platform temp area (the SAME writable-root set the Seatbelt profile grants,
+ * derived from the one `writableRoots` function so bash and fs cannot drift);
+ * `danger-full-access` delegates unfenced. A denial throws the structured
+ * `FS_SANDBOX_DENIED` — no text inference is needed (unlike bash's kernel
+ * stderr), because an in-process fence knows exactly what it refused. The
+ * escalation retry lives in the tool layer (`@deepseek-ai/dsh-tool-fs`),
+ * exactly as bash's does.
+ *
+ * @module @deepseek-ai/dsh-fs-sandbox
+ */
+
+import { sep } from 'node:path'
+import { Context } from 'cordis'
+import { LocalFileSystem } from '@deepseek-ai/dsh-fs-local'
+import type { Config as LocalConfig } from '@deepseek-ai/dsh-fs-local'
+import { FsError } from '@deepseek-ai/dsh-fs'
+import type { FsEditOutcome, FsEditRequest, FsTarget, FsVersion, FsWriteIntent, FsWriteOutcome } from '@deepseek-ai/dsh-fs'
+import { writableRoots } from '@deepseek-ai/dsh-sandbox'
+import type { SandboxMode } from '@deepseek-ai/dsh-sandbox'
+import type {} from '@deepseek-ai/dsh-sandbox-policy'
+
+/**
+ * Plugin config: the local backend's knobs, verbatim (only `cwd`, the resolve
+ * base for relative paths). The sandbox default (mode + `workspace-write`
+ * boundary root) is NOT here — it lives on `ctx.sandboxPolicy`, the one home
+ * both enforcing families share.
+ */
+export type Config = LocalConfig
+
+/** Whether `path` is `root` itself or lies beneath it (both already canonical). */
+function isUnder(path: string, root: string): boolean {
+  if (path === root) return true
+  const prefix = root.endsWith(sep) ? root : root + sep
+  return path.startsWith(prefix)
+}
+
+/**
+ * Sandbox-enforcing filesystem backend. Registers as `ctx.fs` (loading it
+ * INSTEAD OF `dsh-fs-local`, together with a `ctx.sandboxPolicy`, is the whole
+ * swap — the model-facing tools are untouched). Its configured default mode is
+ * the fallback exposed by {@link sandboxMode}; `dsh-tool-fs` folds a session's
+ * `sandbox/mode` override and stamps the effective mode onto each mutation,
+ * while an approved escalation may stamp a strictly wider mode for one call.
+ */
+export class SandboxedFileSystem extends LocalFileSystem {
+  static inject = ['sandboxPolicy']
+
+  private readonly defaultMode: SandboxMode
+  /**
+   * The canonical roots a `workspace-write` mutation may land under, computed
+   * once (the workspace root and platform temp areas are fixed for the
+   * provider's lifetime): the same set {@link writableRoots} gives every
+   * enforcement dialect, so the fs fence and the bash runner agree.
+   */
+  private readonly writableRoots: string[]
+
+  constructor(ctx: Context, config: Config) {
+    super(ctx, config)
+    this.defaultMode = ctx.sandboxPolicy.defaultMode
+    this.writableRoots = writableRoots({ mode: 'workspace-write', workspaceRoot: ctx.sandboxPolicy.workspaceRoot })
+  }
+
+  /** The deployment default mode — the capability fact the tool layer reads to advertise escalation. */
+  override get sandboxMode(): SandboxMode {
+    return this.defaultMode
+  }
+
+  /**
+   * Fence the write by the per-call mode, then delegate to the inherited
+   * atomic write. See {@link assertWritable}.
+   * @param target - the resolved target to write.
+   * @param content - the full new file content.
+   * @param expected - the write intent guarding the write; omit for unconditional.
+   * @param signal - aborts before the atomic rename takes effect.
+   * @param sandboxMode - the per-call mode; omit to use the deployment default.
+   * @returns the write outcome from the inherited backend.
+   */
+  override async writeText(
+    target: FsTarget,
+    content: string,
+    expected?: FsWriteIntent,
+    signal?: AbortSignal,
+    sandboxMode?: SandboxMode,
+  ): Promise<FsWriteOutcome> {
+    await this.assertWritable(target, sandboxMode)
+    return super.writeText(target, content, expected, signal)
+  }
+
+  /**
+   * Fence the edit by the per-call mode, then delegate to the inherited
+   * atomic edit. See {@link assertWritable}.
+   * @param target - the resolved target to edit.
+   * @param edit - the literal search/replace request.
+   * @param expected - the version guard; omit for an unconditional edit.
+   * @param signal - aborts before the atomic rename takes effect.
+   * @param sandboxMode - the per-call mode; omit to use the deployment default.
+   * @returns the edit outcome from the inherited backend.
+   */
+  override async editText(
+    target: FsTarget,
+    edit: FsEditRequest,
+    expected?: { version: FsVersion },
+    signal?: AbortSignal,
+    sandboxMode?: SandboxMode,
+  ): Promise<FsEditOutcome> {
+    await this.assertWritable(target, sandboxMode)
+    return super.editText(target, edit, expected, signal)
+  }
+
+  /**
+   * Enforce the per-call mode against `target` before delegating the mutation.
+   * `read-only` denies; `workspace-write` re-canonicalizes the target NOW
+   * (`resolve` realpaths the deepest existing ancestor, reflecting a
+   * concurrently swapped symlink) and requires containment under a writable
+   * root; `danger-full-access` allows. Throws the structured
+   * `FS_SANDBOX_DENIED` on refusal — the tool layer maps it to the model-facing
+   * `[sandbox: …]` marker and the escalation hint.
+   */
+  private async assertWritable(target: FsTarget, sandboxMode?: SandboxMode): Promise<void> {
+    const mode = sandboxMode ?? this.defaultMode
+    if (mode === 'danger-full-access') return
+    if (mode === 'read-only') {
+      throw new FsError(`cannot write "${target.displayPath}": file access denied under read-only mode`, 'FS_SANDBOX_DENIED')
+    }
+    // workspace-write: containment on the FRESH canonical path (catches a
+    // symlink ancestor swapped since the tool resolved this target).
+    const fresh = await this.resolve(target.displayPath)
+    if (!this.writableRoots.some(root => isUnder(fresh.targetKey, root))) {
+      throw new FsError(`cannot write "${target.displayPath}": file access denied under workspace-write mode`, 'FS_SANDBOX_DENIED')
+    }
+  }
+}
+
+export default SandboxedFileSystem

packages/fs/fs-sandbox/tests/fs-sandbox.spec.ts

@@ -0,0 +1,224 @@
+/**
+ * Tests for the sandbox-enforcing filesystem backend: the per-call mode fence
+ * on write/edit (read-only denies, workspace-write contains, danger-full-access
+ * passes through), reads always passing through, the capability fact, and the
+ * containment matrix — `..` traversal, absolute paths outside, and symlink
+ * escapes (a symlinked directory inside the workspace pointing out, and a new
+ * file created under one). The fence is exercised on a real filesystem: a
+ * denied write leaves no file on disk.
+ */
+
+import { afterEach, beforeEach, describe, expect, it } from 'vitest'
+import { mkdir, mkdtemp, readFile, rm, symlink, writeFile } from 'node:fs/promises'
+import { existsSync } from 'node:fs'
+import { homedir, tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { Context } from 'cordis'
+import { FsError } from '@deepseek-ai/dsh-fs'
+import type { FsTarget } from '@deepseek-ai/dsh-fs'
+import SandboxPolicyService from '@deepseek-ai/dsh-sandbox-policy'
+import type { SandboxMode } from '@deepseek-ai/dsh-sandbox'
+import { SandboxedFileSystem } from '@deepseek-ai/dsh-fs-sandbox'
+
+let base: string
+let workspace: string
+let outside: string
+let ctx: Context
+let fs: SandboxedFileSystem
+let fiber: Awaited<ReturnType<Context['plugin']>>
+
+async function boot(mode: SandboxMode): Promise<void> {
+  ctx = new Context()
+  await ctx.plugin(SandboxPolicyService, { mode, workspaceRoot: workspace })
+  fiber = await ctx.plugin(SandboxedFileSystem, { cwd: workspace })
+  fs = ctx.fs as SandboxedFileSystem
+}
+
+beforeEach(async () => {
+  // Base under HOME, deliberately NOT tmpdir: `workspace-write` grants /tmp and
+  // os.tmpdir() (parity with the bash runner), so an "outside" dir under tmpdir
+  // would be legitimately writable. Sibling dirs under HOME are outside every
+  // grant, so containment failures are real denials. (The bwrap e2e roots its
+  // workspaces under HOME for the same reason.)
+  base = await mkdtemp(join(homedir(), '.dsh-fssbx-'))
+  workspace = join(base, 'ws')
+  outside = join(base, 'out')
+  await mkdir(workspace)
+  await mkdir(outside)
+})
+afterEach(async () => {
+  await fiber?.dispose()
+  await rm(base, { recursive: true, force: true })
+})
+
+/** Resolve a path through the backend and return its target. */
+function target(path: string): Promise<FsTarget> {
+  return fs.resolve(path)
+}
+
+describe('the capability fact', () => {
+  it('reports the deployment default mode (what the tool layer advertises against)', async () => {
+    await boot('workspace-write')
+    expect(fs.sandboxMode).toBe('workspace-write')
+  })
+})
+
+describe('read-only', () => {
+  beforeEach(() => boot('read-only'))
+
+  it('denies write, leaving no file on disk', async () => {
+    const path = join(workspace, 'denied.txt')
+    await expect(fs.writeText(await target(path), 'x')).rejects.toMatchObject({ code: 'FS_SANDBOX_DENIED' })
+    expect(existsSync(path)).toBe(false)
+  })
+
+  it('denies edit of an existing file (the content is unchanged)', async () => {
+    const path = join(workspace, 'file.txt')
+    await writeFile(path, 'original')
+    await expect(fs.editText(await target(path), { oldString: 'original', newString: 'changed', replaceAll: false }))
+      .rejects.toMatchObject({ code: 'FS_SANDBOX_DENIED' })
+    expect(await readFile(path, 'utf8')).toBe('original')
+  })
+
+  it('allows reads (every mode permits reading)', async () => {
+    const path = join(workspace, 'readable.txt')
+    await writeFile(path, 'hello')
+    expect(await fs.readText(await target(path))).toBe('hello')
+  })
+})
+
+describe('workspace-write containment', () => {
+  beforeEach(() => boot('workspace-write'))
+
+  it('a write under the workspace lands', async () => {
+    const path = join(workspace, 'nested', 'ok.txt')
+    const outcome = await fs.writeText(await target(path), 'inside')
+    expect(outcome.operation).toBe('create')
+    expect(await readFile(path, 'utf8')).toBe('inside')
+  })
+
+  it('a write to the platform temp area lands (parity with the bash runner grant)', async () => {
+    const path = join(await mkdtemp(join(tmpdir(), 'dsh-fssbx-tmp-')), 'temp.txt')
+    await fs.writeText(await target(path), 'temp')
+    expect(await readFile(path, 'utf8')).toBe('temp')
+  })
+
+  it('an absolute path outside the workspace is denied, no file created', async () => {
+    const path = join(outside, 'escape.txt')
+    await expect(fs.writeText(await target(path), 'x')).rejects.toMatchObject({ code: 'FS_SANDBOX_DENIED' })
+    expect(existsSync(path)).toBe(false)
+  })
+
+  it('a `..` traversal out of the workspace is denied', async () => {
+    const path = join(workspace, '..', 'sibling-escape.txt')
+    await expect(fs.writeText(await target(path), 'x')).rejects.toMatchObject({ code: 'FS_SANDBOX_DENIED' })
+    expect(existsSync(join(workspace, '..', 'sibling-escape.txt'))).toBe(false)
+  })
+
+  it('a symlinked directory inside the workspace pointing OUT is denied (canonicalized before containment)', async () => {
+    // workspace/link -> outside ; writing workspace/link/f.txt would land in outside/f.txt.
+    await symlink(outside, join(workspace, 'link'))
+    const path = join(workspace, 'link', 'f.txt')
+    await expect(fs.writeText(await target(path), 'x')).rejects.toMatchObject({ code: 'FS_SANDBOX_DENIED' })
+    expect(existsSync(join(outside, 'f.txt'))).toBe(false)
+  })
+
+  it('a NEW file created under a symlinked-out directory is denied (deepest-ancestor realpath)', async () => {
+    await symlink(outside, join(workspace, 'link'))
+    const path = join(workspace, 'link', 'newdir', 'deep.txt')
+    await expect(fs.writeText(await target(path), 'x')).rejects.toMatchObject({ code: 'FS_SANDBOX_DENIED' })
+    expect(existsSync(join(outside, 'newdir'))).toBe(false)
+  })
+
+  it('an edit outside the workspace is denied; the original is untouched', async () => {
+    const path = join(outside, 'file.txt')
+    await writeFile(path, 'original')
+    await expect(fs.editText(await target(path), { oldString: 'original', newString: 'x', replaceAll: false }))
+      .rejects.toMatchObject({ code: 'FS_SANDBOX_DENIED' })
+    expect(await readFile(path, 'utf8')).toBe('original')
+  })
+
+  it('an edit inside the workspace lands', async () => {
+    const path = join(workspace, 'edit.txt')
+    await writeFile(path, 'original')
+    const outcome = await fs.editText(await target(path), { oldString: 'original', newString: 'changed', replaceAll: false })
+    expect(outcome.after).toBe('changed')
+    expect(await readFile(path, 'utf8')).toBe('changed')
+  })
+
+  it('the workspace root itself passes the fence (path equal to a writable root), failing only on file type', async () => {
+    // isUnder's path-equals-root branch: the fence allows the root, and the
+    // write then fails because the root is a directory, not a regular file.
+    await expect(fs.writeText(await target(workspace), 'x')).rejects.toMatchObject({ code: 'FS_NOT_REGULAR_FILE' })
+  })
+})
+
+describe('workspace-write with the filesystem root as the workspace (a root ending in the path separator)', () => {
+  it('grants writes anywhere: containment against `/` allows any absolute path', async () => {
+    // A degenerate but valid config — workspaceRoot '/'. It exercises isUnder's
+    // separator-suffixed-root branch: `/` already ends in the separator, so the
+    // prefix stays `/` and every absolute path is contained.
+    const rootCtx = new Context()
+    await rootCtx.plugin(SandboxPolicyService, { mode: 'workspace-write', workspaceRoot: '/' })
+    const rootFiber = await rootCtx.plugin(SandboxedFileSystem, { cwd: workspace })
+    const rootFs = rootCtx.fs as SandboxedFileSystem
+    try {
+      const path = join(base, 'anywhere.txt') // under HOME, outside /tmp — allowed only via the `/` root
+      await rootFs.writeText(await rootFs.resolve(path), 'anywhere')
+      expect(await readFile(path, 'utf8')).toBe('anywhere')
+    } finally {
+      await rootFiber.dispose()
+    }
+  })
+})
+
+describe('danger-full-access', () => {
+  beforeEach(() => boot('danger-full-access'))
+
+  it('writes anywhere, unfenced', async () => {
+    const path = join(outside, 'free.txt')
+    await fs.writeText(await target(path), 'free')
+    expect(await readFile(path, 'utf8')).toBe('free')
+  })
+})
+
+describe('the per-call mode override (escalation)', () => {
+  it('a workspace-write stamp on a read-only default lets a contained write land for that call only', async () => {
+    await boot('read-only')
+    const path = join(workspace, 'escalated.txt')
+    // Default read-only would deny; the per-call workspace-write stamp allows it (contained).
+    await fs.writeText(await target(path), 'granted', undefined, undefined, 'workspace-write')
+    expect(await readFile(path, 'utf8')).toBe('granted')
+    // A neighboring plain call still runs under the read-only default.
+    await expect(fs.writeText(await target(join(workspace, 'plain.txt')), 'x'))
+      .rejects.toMatchObject({ code: 'FS_SANDBOX_DENIED' })
+  })
+
+  it('a danger-full-access stamp bypasses the fence for that call', async () => {
+    await boot('read-only')
+    const path = join(outside, 'granted-full.txt')
+    await fs.writeText(await target(path), 'full', undefined, undefined, 'danger-full-access')
+    expect(await readFile(path, 'utf8')).toBe('full')
+  })
+})
+
+describe('registration and HMR safety', () => {
+  it('registers as ctx.fs and unregisters cleanly from a child fiber', async () => {
+    await boot('workspace-write')
+    expect(ctx.fs).toBeInstanceOf(SandboxedFileSystem)
+    await fiber.dispose()
+    expect(ctx.get('fs')).toBeUndefined()
+    // Re-mount below the disposed one to prove no lingering registration.
+    fiber = await ctx.plugin(SandboxedFileSystem, { cwd: workspace })
+    expect(ctx.fs).toBeInstanceOf(SandboxedFileSystem)
+  })
+})
+
+describe('FsError identity', () => {
+  it('the denial is a structured FsError distinct from a host permission error', async () => {
+    await boot('read-only')
+    const error = await fs.writeText(await target(join(workspace, 'x.txt')), 'x').catch((e: unknown) => e)
+    expect(error).toBeInstanceOf(FsError)
+    expect((error as FsError).code).toBe('FS_SANDBOX_DENIED')
+  })
+})

packages/fs/fs-sandbox/tsconfig.json

@@ -0,0 +1,30 @@
+{
+  "extends": "../../../tsconfig.base.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "lib/types"
+  },
+  "include": [
+    "src"
+  ],
+  "references": [
+    {
+      "path": "../../../vendor/cosmokit"
+    },
+    {
+      "path": "../../../vendor/cordis"
+    },
+    {
+      "path": "../fs"
+    },
+    {
+      "path": "../fs-local"
+    },
+    {
+      "path": "../../sandbox/sandbox"
+    },
+    {
+      "path": "../../sandbox/sandbox-policy"
+    }
+  ]
+}

packages/fs/fs/package.json

@@ -24,11 +24,13 @@
   "peerDependencies": {
     "@deepseek-ai/dsh-brand": "^0.0.1",
     "@deepseek-ai/dsh-llm": "^0.0.1",
+    "@deepseek-ai/dsh-sandbox": "^0.0.1",
     "cordis": "^4.0.0-rc.6"
   },
   "devDependencies": {
     "@deepseek-ai/dsh-brand": "workspace:^",
     "@deepseek-ai/dsh-llm": "workspace:^",
+    "@deepseek-ai/dsh-sandbox": "workspace:^",
     "cordis": "^4.0.0-rc.6"
   }
 }

packages/fs/fs/src/index.ts

@@ -58,6 +58,7 @@
  */
 
 import { Context, Service } from 'cordis'
+import type { SandboxMode } from '@deepseek-ai/dsh-sandbox'
 import type {
   FsDirEntry,
   FsEditOutcome,
@@ -174,6 +175,22 @@ export abstract class FileSystem extends Service {
     super(ctx, 'fs')
   }
 
+  /**
+   * The sandbox mode this backend enforces on mutations BY DEFAULT, or
+   * `undefined` when it does not confine at all — the capability fact the tool
+   * layer reads to advertise the escalation fields honestly (mirrors
+   * `BashExecutor.sandboxMode`). The base class and the bare local backend
+   * report `undefined`; a sandboxing backend (`@deepseek-ai/dsh-fs-sandbox`)
+   * overrides it with the deployment default. A session override may make the
+   * effective mode narrower or wider, so strict escalation widening is checked
+   * per call rather than encoded in this default-relative fact.
+   * @returns the configured default mode of a sandboxing backend; `undefined`
+   *   for a backend that never confines.
+   */
+  get sandboxMode(): SandboxMode | undefined {
+    return undefined
+  }
+
   /**
    * Resolve a model/plugin-supplied path into a stable {@link FsTarget}. May
    * perform I/O (a remote/sandboxed backend may need a round-trip to map a path
@@ -238,9 +255,18 @@ export abstract class FileSystem extends Service {
    * @param content - the full new file content.
    * @param expected - the write intent guarding the write; omit for unconditional.
    * @param signal - aborts before the atomic rename takes effect.
+   * @param sandboxMode - the per-call sandbox mode this write runs under; a
+   *   sandboxing backend fences the write by it, the bare backend ignores it.
+   *   Omit to leave the backend its own default.
    * @returns the outcome, including the version the write produced.
    */
-  abstract writeText(target: FsTarget, content: string, expected?: FsWriteIntent, signal?: AbortSignal): Promise<FsWriteOutcome>
+  abstract writeText(
+    target: FsTarget,
+    content: string,
+    expected?: FsWriteIntent,
+    signal?: AbortSignal,
+    sandboxMode?: SandboxMode,
+  ): Promise<FsWriteOutcome>
 
   /**
    * Apply a literal edit to an existing UTF-8 text file. When `expected` is
@@ -252,9 +278,18 @@ export abstract class FileSystem extends Service {
    * @param edit - the literal search/replace request.
    * @param expected - the version guard; omit for an unconditional edit.
    * @param signal - aborts before the atomic rename takes effect.
+   * @param sandboxMode - the per-call sandbox mode this edit runs under; a
+   *   sandboxing backend fences the edit by it, the bare backend ignores it.
+   *   Omit to leave the backend its own default.
    * @returns the outcome, including the version the edit produced.
    */
-  abstract editText(target: FsTarget, edit: FsEditRequest, expected?: { version: FsVersion }, signal?: AbortSignal): Promise<FsEditOutcome>
+  abstract editText(
+    target: FsTarget,
+    edit: FsEditRequest,
+    expected?: { version: FsVersion },
+    signal?: AbortSignal,
+    sandboxMode?: SandboxMode,
+  ): Promise<FsEditOutcome>
 }
 
 export default FileSystem

packages/fs/fs/src/types.ts

@@ -173,6 +173,7 @@ export type FsErrorCode =
   | 'FS_NOT_TEXT'
   | 'FS_NOT_REGULAR_FILE'
   | 'FS_PERMISSION_DENIED'
+  | 'FS_SANDBOX_DENIED'
   | 'FS_IO_ERROR'
   | 'FS_STALE_VERSION'
   | 'FS_NOT_OBSERVED'

packages/fs/fs/tsconfig.json

@@ -9,6 +9,7 @@
     { "path": "../../../vendor/cosmokit" },
     { "path": "../../../vendor/cordis" },
     { "path": "../../util/brand" },
-    { "path": "../../llm/llm" }
+    { "path": "../../llm/llm" },
+    { "path": "../../sandbox/sandbox" }
   ]
 }

packages/fs/tool-fs/package.json

@@ -28,9 +28,12 @@
   "peerDependencies": {
     "@deepseek-ai/dsh-fs": "^0.0.1",
     "@deepseek-ai/dsh-llm": "^0.0.1",
+    "@deepseek-ai/dsh-sandbox": "^0.0.1",
+    "@deepseek-ai/dsh-sandbox-policy": "^0.0.1",
     "@deepseek-ai/dsh-session": "^0.0.1",
     "@deepseek-ai/dsh-system-prompt": "^0.0.1",
     "@deepseek-ai/dsh-tools": "^0.0.1",
+    "@deepseek-ai/dsh-user-approval": "^0.0.1",
     "cordis": "^4.0.0-rc.6"
   },
   "devDependencies": {
@@ -41,9 +44,12 @@
     "@deepseek-ai/dsh-fs-local": "workspace:^",
     "@deepseek-ai/dsh-llm": "workspace:^",
     "@deepseek-ai/dsh-llm-deepseek": "workspace:^",
+    "@deepseek-ai/dsh-sandbox": "workspace:^",
+    "@deepseek-ai/dsh-sandbox-policy": "workspace:^",
     "@deepseek-ai/dsh-session": "workspace:^",
     "@deepseek-ai/dsh-system-prompt": "workspace:^",
     "@deepseek-ai/dsh-tools": "workspace:^",
+    "@deepseek-ai/dsh-user-approval": "workspace:^",
     "cordis": "^4.0.0-rc.6"
   }
 }

packages/fs/tool-fs/src/edit.ts

@@ -20,6 +20,7 @@ import type {} from '@deepseek-ai/dsh-fs'
 import type {} from '@deepseek-ai/dsh-system-prompt'
 import { computeHunkDiffs, diffsFromMeta, type FsDiffMeta } from './diff.ts'
 import { sessionCwd } from './session-cwd.ts'
+import type { FsSandboxSurface } from './sandbox.ts'
 
 /** Validated `edit` arguments after defaulting. */
 interface EditInput {
@@ -29,6 +30,20 @@ interface EditInput {
   replaceAll: boolean
 }
 
+/**
+ * The `edit` tool's validated argument shape: the base parameters plus the two
+ * escalation fields, advertised only under a confining `ctx.fs` (absent from
+ * the schema otherwise, so the validator rejects them before `execute`).
+ */
+interface EditToolArgs {
+  file_path: string
+  old_string: string
+  new_string: string
+  replace_all?: boolean
+  sandbox_permissions?: string
+  justification?: string
+}
+
 /**
  * Validate value constraints the schema DSL can't express: a non-blank
  * `file_path`, a non-empty `old_string`, and `old_string !== new_string`
@@ -63,8 +78,9 @@ export function formatEditOutput(displayPath: string, replaceAll: boolean): stri
 /**
  * Register the `edit` tool and its system-prompt guidance.
  * @param ctx - the plugin context; registrations are effects scoped to it, and execution uses its `fs` service.
+ * @param sandbox - the shared sandbox-escalation surface (advertisement, mode stamping, denial mapping).
  */
-export function applyEditTool(ctx: Context): void {
+export function applyEditTool(ctx: Context, sandbox: FsSandboxSurface): void {
   ctx.systemPrompt.section({
     name: 'tool:edit',
     order: 102,
@@ -79,21 +95,32 @@ export function applyEditTool(ctx: Context): void {
       old_string: { type: 'string', required: true, description: 'Literal text to replace. Must match exactly.' },
       new_string: { type: 'string', required: true, description: 'Literal replacement text. Use an empty string to delete the match.' },
       replace_all: { type: 'boolean', description: 'Replace all matches. Defaults to false; when false, old_string must appear exactly once.' },
+      ...sandbox.escalationModes.length > 0 ? sandbox.schemaFields() : {},
     },
-    async execute(args, exec): Promise<{ content: ContentBlock[]; meta?: FsDiffMeta }> {
+    async execute(args: EditToolArgs, exec): Promise<{ content: ContentBlock[]; meta?: FsDiffMeta }> {
       const input = parseEditArgs(args)
+      // Resolve the per-call sandbox mode (escalation grant > session override
+      // > backend default) BEFORE anything executes.
+      const sandboxMode = await sandbox.stampMode('edit', args, exec)
       const cwd = sessionCwd(exec)
       const target = await ctx.fs.resolve(input.filePath, cwd !== undefined ? { cwd } : undefined)
       // Single-slot decision: the policy plugin returns { version: vObserved } or
       // throws FS_NOT_OBSERVED; the bare default is undefined (unconditional edit).
       // No stat — the bare default never manufactures a version basis.
       const intent = await ctx.waterfall('fs/edit-intent', target, exec, () => undefined)
-      const outcome = await ctx.fs.editText(
-        target,
-        { oldString: input.oldString, newString: input.newString, replaceAll: input.replaceAll },
-        intent,
-        exec.signal,
-      )
+      let outcome
+      try {
+        outcome = await ctx.fs.editText(
+          target,
+          { oldString: input.oldString, newString: input.newString, replaceAll: input.replaceAll },
+          intent,
+          exec.signal,
+          sandboxMode,
+        )
+      } catch (error: unknown) {
+        // A sandbox denial becomes the shared [sandbox: …] marker; any other error passes through.
+        throw sandbox.mapError(error, sandboxMode)
+      }
       // Record the observed version (a no-op when no policy plugin listens).
       ctx.emit('fs/observed', target, outcome.version, exec)
       // The result-time applied-hunk diff (before→after with context lines). An

packages/fs/tool-fs/src/index.ts

@@ -24,10 +24,12 @@
 
 import type { Context } from 'cordis'
 import z from 'schemastery'
+import type {} from '@deepseek-ai/dsh-user-approval'
 import { applyReadTool, READ_LIMIT, STREAM_MIN_SIZE } from './read.ts'
 import { applyWriteTool } from './write.ts'
 import { applyEditTool } from './edit.ts'
 import { READ_MAX_BYTES, READ_MAX_LINE_LENGTH } from './read-render.ts'
+import { FsSandboxSurface } from './sandbox.ts'
 
 export { READ_LIMIT, STREAM_MIN_SIZE, applyReadTool, parseReadArgs } from './read.ts'
 export type { ReadToolCaps } from './read.ts'
@@ -37,6 +39,8 @@ export { READ_MAX_BYTES, READ_MAX_LINE_LENGTH, buildWindow, formatReadOutput } f
 export type { FileReadOutcome, FileTextLine, ReadWindow, WindowResult } from './read-render.ts'
 export { DIFF_CONTEXT, computeHunkDiffs, diffsFromMeta } from './diff.ts'
 export type { FsDiffMeta } from './diff.ts'
+export { FsSandboxSurface } from './sandbox.ts'
+export type { EscalationSchemaFields, FsEscalationArgs } from './sandbox.ts'
 
 /** Cordis plugin name used by loader diagnostics. */
 export const name = 'tool-fs'
@@ -87,6 +91,10 @@ export function apply(ctx: Context, config: Config): void {
     maxBytes: resolved.readMaxBytes,
     streamMinSize: resolved.readStreamMinSize,
   })
-  applyWriteTool(ctx)
-  applyEditTool(ctx)
+  // One escalation surface shared by both mutating tools: advertisement gating,
+  // per-call mode stamping, and denial-marker mapping, all keyed off whether
+  // the mounted ctx.fs confines (ctx.fs.sandboxMode).
+  const sandbox = new FsSandboxSurface(ctx)
+  applyWriteTool(ctx, sandbox)
+  applyEditTool(ctx, sandbox)
 }

packages/fs/tool-fs/src/sandbox.ts

@@ -0,0 +1,132 @@
+/**
+ * The sandbox-escalation surface shared by the `write` and `edit` tools: the
+ * per-call mode stamp, the advertised escalation fields, and the denial-marker
+ * mapping — all delegating the vocabulary and the fail-closed approval
+ * sequence to `@deepseek-ai/dsh-sandbox` (the same pieces `@deepseek-ai/dsh-tool-bash`
+ * uses), so bash and fs escalate identically. Built ONCE per plugin from
+ * `ctx.fs.sandboxMode` (the capability fact — is a confining backend mounted?)
+ * and shared by both mutating tools.
+ *
+ * @module @deepseek-ai/dsh-tool-fs/sandbox
+ */
+
+import type { Context } from 'cordis'
+import type { ToolExecution } from '@deepseek-ai/dsh-tools'
+import type { SandboxMode } from '@deepseek-ai/dsh-sandbox'
+import { ESCALATION_TARGETS, approveEscalation, escalationHintMarker, sandboxDenialMarker, validateEscalationArgs } from '@deepseek-ai/dsh-sandbox'
+import { effectiveSandboxMode } from '@deepseek-ai/dsh-sandbox-policy'
+import { FsError } from '@deepseek-ai/dsh-fs'
+
+/** The two escalation arguments a mutating tool may carry (advertised only under a confining backend). */
+export interface FsEscalationArgs {
+  sandbox_permissions?: string
+  justification?: string
+}
+
+/** The schema fields for the escalation arguments, spread into a tool's `parameters` when a confining backend is mounted. */
+export interface EscalationSchemaFields {
+  sandbox_permissions: { type: 'string'; enum: string[]; description: string }
+  justification: { type: 'string'; description: string }
+}
+
+/**
+ * The filesystem escalation surface: advertisement gating, per-call mode
+ * stamping (folding the session's `sandbox/mode` override), the one-approved
+ * wider retry, and denial-marker mapping. A pure product of `ctx` at plugin
+ * apply time.
+ */
+export class FsSandboxSurface {
+  /** The escalation targets this composition advertises (`[]` when no confining backend is mounted). */
+  readonly escalationModes: readonly SandboxMode[]
+  /** The backend's default mode, or `undefined` when `ctx.fs` does not confine. */
+  private readonly defaultMode: SandboxMode | undefined
+
+  constructor(private readonly ctx: Context) {
+    this.defaultMode = ctx.fs.sandboxMode
+    this.escalationModes = this.defaultMode === undefined ? [] : ESCALATION_TARGETS
+  }
+
+  /**
+   * The escalation schema fields for a mutating tool's `parameters`. Call it
+   * only under a confining backend (guard on {@link escalationModes}); the
+   * enum pins the closed target vocabulary, the strict-wider check happens per
+   * call at execution.
+   * @returns the two escalation parameter specs.
+   */
+  schemaFields(): EscalationSchemaFields {
+    return {
+      sandbox_permissions: {
+        type: 'string',
+        enum: [...this.escalationModes],
+        description: 'The wider sandbox mode this file operation needs. Only valid as a one-shot retry '
+          + 'of an operation the sandbox just denied; requires justification and user approval.',
+      },
+      justification: {
+        type: 'string',
+        description: 'Required with sandbox_permissions: one sentence for the user explaining '
+          + 'why this exact file operation needs the wider access.',
+      },
+    }
+  }
+
+  /**
+   * The session's standing mode override for an ordinary (non-escalating)
+   * call — the `sandbox/mode` fold of the calling agent's log. Undefined for a
+   * non-confining backend and for agent-less callers.
+   */
+  private sessionOverride(exec: ToolExecution): SandboxMode | undefined {
+    if (this.defaultMode === undefined || exec.agent === undefined) return undefined
+    return effectiveSandboxMode(exec.agent.session.events)
+  }
+
+  /**
+   * The mode to STAMP onto this mutation: an approved escalation grant (a
+   * strictly wider retry resolved through `ctx.approval` before anything
+   * executes), else the session's standing override, else `undefined` (the
+   * backend applies its own default). Validates the escalation argument
+   * pairing first.
+   * @param toolName - the mutating tool's name, for the approval audit trail.
+   * @param args - the call's escalation arguments.
+   * @param exec - the tool-execution context (agent, callId, signal).
+   * @returns the mode to pass to the mutation, or undefined for the backend default.
+   */
+  async stampMode(toolName: string, args: FsEscalationArgs, exec: ToolExecution): Promise<SandboxMode | undefined> {
+    validateEscalationArgs(args.sandbox_permissions, args.justification)
+    if (args.sandbox_permissions === undefined || args.justification === undefined) {
+      return this.sessionOverride(exec)
+    }
+    if (this.escalationModes.length === 0) {
+      throw new Error('sandbox_permissions is not available in this composition (no sandboxing filesystem to escalate)')
+    }
+    const effectiveMode = (this.sessionOverride(exec) ?? this.defaultMode) as SandboxMode
+    return approveEscalation(
+      { requestedMode: args.sandbox_permissions, justification: args.justification, effectiveMode, subject: 'operation' },
+      {
+        approver: this.ctx.get('approval'),
+        agent: exec.agent,
+        callId: exec.callId,
+        toolName,
+        ...exec.signal ? { signal: exec.signal } : {},
+      },
+    )
+  }
+
+  /**
+   * Map a thrown provider error for the model: a `FS_SANDBOX_DENIED` becomes an
+   * error whose text is the shared `[sandbox: …]` denial marker plus the
+   * same-turn escalation hint, so a policy denial reads identically to bash's;
+   * any other error passes through unchanged. A `FS_SANDBOX_DENIED` only arises
+   * under a confining backend, which always advertises the escalation fields,
+   * so the hint always applies here.
+   * @param error - the error thrown by the mutation.
+   * @param stampedMode - the mode stamped onto the call (names the mode in the marker).
+   * @returns the error to throw — the marker error for a sandbox denial, else the original.
+   */
+  mapError(error: unknown, stampedMode: SandboxMode | undefined): unknown {
+    if (!(error instanceof FsError) || error.code !== 'FS_SANDBOX_DENIED') return error
+    // A FS_SANDBOX_DENIED only arises under a confining backend, so defaultMode
+    // (hence the resolved mode) is defined here.
+    const mode = (stampedMode ?? this.defaultMode) as SandboxMode
+    return new Error(`${sandboxDenialMarker(mode)}\n${escalationHintMarker('operation')}`)
+  }
+}

packages/fs/tool-fs/src/write.ts

@@ -20,6 +20,7 @@ import type {} from '@deepseek-ai/dsh-fs'
 import type {} from '@deepseek-ai/dsh-system-prompt'
 import { computeHunkDiffs, diffsFromMeta, type FsDiffMeta } from './diff.ts'
 import { sessionCwd } from './session-cwd.ts'
+import type { FsSandboxSurface } from './sandbox.ts'
 
 /**
  * Validate value constraints the schema DSL can't express: only a non-blank
@@ -47,11 +48,24 @@ ${verb} file
 </content>`
 }
 
+/**
+ * The `write` tool's validated argument shape: the base parameters plus the
+ * two escalation fields, advertised only under a confining `ctx.fs` (absent
+ * from the schema otherwise, so the validator rejects them before `execute`).
+ */
+interface WriteToolArgs {
+  file_path: string
+  content: string
+  sandbox_permissions?: string
+  justification?: string
+}
+
 /**
  * Register the `write` tool and its system-prompt guidance.
  * @param ctx - the plugin context; registrations are effects scoped to it, and execution uses its `fs` service.
+ * @param sandbox - the shared sandbox-escalation surface (advertisement, mode stamping, denial mapping).
  */
-export function applyWriteTool(ctx: Context): void {
+export function applyWriteTool(ctx: Context, sandbox: FsSandboxSurface): void {
   ctx.systemPrompt.section({
     name: 'tool:write',
     order: 101,
@@ -64,15 +78,27 @@ export function applyWriteTool(ctx: Context): void {
     parameters: {
       file_path: { type: 'string', required: true, description: 'Path to write, resolved by the filesystem backend.' },
       content: { type: 'string', required: true, description: 'Full UTF-8 text content to write.' },
+      ...sandbox.escalationModes.length > 0 ? sandbox.schemaFields() : {},
     },
-    async execute(args, exec): Promise<{ content: ContentBlock[]; meta?: FsDiffMeta }> {
+    async execute(args: WriteToolArgs, exec): Promise<{ content: ContentBlock[]; meta?: FsDiffMeta }> {
       const input = parseWriteArgs(args)
+      // Resolve the per-call sandbox mode (escalation grant > session override
+      // > backend default) BEFORE anything executes; an escalating call
+      // resolves approval here and throws its distinct text on any non-grant.
+      const sandboxMode = await sandbox.stampMode('write', args, exec)
       const cwd = sessionCwd(exec)
       const target = await ctx.fs.resolve(input.filePath, cwd !== undefined ? { cwd } : undefined)
       // Single-slot decision: the policy plugin produces createIfAbsent/
       // replaceIfVersion; the bare default is undefined (unconditional). No stat.
       const intent = await ctx.waterfall('fs/write-intent', target, exec, () => undefined)
-      const outcome = await ctx.fs.writeText(target, input.content, intent, exec.signal)
+      let outcome: FsWriteOutcome
+      try {
+        outcome = await ctx.fs.writeText(target, input.content, intent, exec.signal, sandboxMode)
+      } catch (error: unknown) {
+        // A sandbox denial becomes the shared [sandbox: …] marker (the model
+        // recognizes it from bash); any other error passes through.
+        throw sandbox.mapError(error, sandboxMode)
+      }
       // Record the observed version (a no-op when no policy plugin listens).
       ctx.emit('fs/observed', target, outcome.version, exec)
       // Attach a contextual hunk as `meta` ONLY for an overwrite (a before-version

packages/fs/tool-fs/tests/tools.spec.ts

@@ -27,6 +27,8 @@ import * as FsPolicy from '@deepseek-ai/dsh-fs-policy'
 import * as ToolFs from '@deepseek-ai/dsh-tool-fs'
 import { formatReadOutput, STREAM_MIN_SIZE } from '@deepseek-ai/dsh-tool-fs'
 import type { FileReadOutcome } from '@deepseek-ai/dsh-tool-fs'
+import ApprovalService from '@deepseek-ai/dsh-user-approval'
+import type { SandboxMode } from '@deepseek-ai/dsh-sandbox'
 
 /** An in-memory fake provider; a test can arm a rejection on any primitive. */
 class FakeFs extends FileSystem {
@@ -570,3 +572,163 @@ describe('read caps are plugin config', () => {
     expect('default' in ToolFs).toBe(false)
   })
 })
+
+describe('sandbox escalation surface (write/edit)', () => {
+  /** A confining fake `ctx.fs`: reports a default mode, records the per-call mode stamped, and can arm a sandbox denial. */
+  class SandboxingFakeFs extends FakeFs {
+    stamped: (SandboxMode | undefined)[] = []
+    override get sandboxMode(): SandboxMode {
+      return 'workspace-write'
+    }
+    override async writeText(
+      target: FsTarget,
+      content: string,
+      expected?: FsWriteIntent,
+      _signal?: AbortSignal,
+      sandboxMode?: SandboxMode,
+    ): Promise<FsWriteOutcome> {
+      this.stamped.push(sandboxMode)
+      return super.writeText(target, content, expected)
+    }
+    override async editText(
+      target: FsTarget,
+      edit: FsEditRequest,
+      expected?: { version: FsVersion },
+      _signal?: AbortSignal,
+      sandboxMode?: SandboxMode,
+    ): Promise<FsEditOutcome> {
+      this.stamped.push(sandboxMode)
+      return super.editText(target, edit, expected)
+    }
+  }
+
+  async function setupConfining(opts: { approval?: boolean } = {}) {
+    const ctx = new Context()
+    await ctx.plugin(SystemPrompt)
+    await ctx.plugin(ToolRegistry)
+    await ctx.plugin(SandboxingFakeFs)
+    await ctx.plugin(FsPolicy)
+    if (opts.approval === true) await ctx.plugin(ApprovalService)
+    await ctx.plugin(ToolFs)
+    return { ctx, fs: ctx.fs as SandboxingFakeFs }
+  }
+
+  /** A fake agent whose session records appends (the approval audit surface), mid-turn, carrying the given events for the fold. */
+  function escalationAgent(events: Array<{ type: string; data?: Record<string, unknown> }> = []): object {
+    return {
+      id: 'agent-fs-esc',
+      session: {
+        header: { version: 0, id: 'sess-fs-esc', createdAt: 0 },
+        events: [{ type: 'turn/start' }, ...events],
+        append: (type: string, data: Record<string, unknown>) => { events.push({ type, data }) },
+      },
+    }
+  }
+
+  function fsSchema(ctx: Context, name: 'write' | 'edit') {
+    const schema = ctx.tools.schemas().find(s => s.name === name)
+    if (!schema) throw new Error(`${name} tool not registered`)
+    return schema as unknown as { parameters: { properties: Record<string, { enum?: string[] }> } }
+  }
+
+  it('advertises no escalation fields under a non-confining backend', async () => {
+    const { ctx } = await setup()
+    expect(ctx.fs.sandboxMode).toBeUndefined()
+    for (const name of ['write', 'edit'] as const) {
+      const props = fsSchema(ctx, name).parameters.properties
+      expect(props['sandbox_permissions']).toBeUndefined()
+      expect(props['justification']).toBeUndefined()
+    }
+  })
+
+  it('advertises the closed target vocabulary on write and edit under a confining backend', async () => {
+    const { ctx } = await setupConfining()
+    for (const name of ['write', 'edit'] as const) {
+      const props = fsSchema(ctx, name).parameters.properties
+      expect(props['sandbox_permissions']?.enum).toEqual(['workspace-write', 'danger-full-access'])
+      expect(props['justification']).toBeDefined()
+    }
+  })
+
+  it('a plain write stamps nothing (backend default) and no session override folds without one', async () => {
+    const { ctx, fs } = await setupConfining()
+    await call(ctx, 'write', { file_path: 'a.txt', content: 'x' }, escalationAgent())
+    expect(fs.stamped).toEqual([undefined])
+  })
+
+  it('a standing session override folds onto the stamp', async () => {
+    const { ctx, fs } = await setupConfining()
+    await call(ctx, 'write', { file_path: 'a.txt', content: 'x' }, escalationAgent([{ type: 'sandbox/mode', data: { mode: 'read-only' } }]))
+    expect(fs.stamped).toEqual(['read-only'])
+  })
+
+  it('a denied write maps to the shared marker plus the escalation hint (isError)', async () => {
+    const { ctx, fs } = await setupConfining()
+    fs.rejectWith = new FsError('denied', 'FS_SANDBOX_DENIED')
+    const result = await call(ctx, 'write', { file_path: 'a.txt', content: 'x' }, escalationAgent())
+    expect(result.isError).toBe(true)
+    expect(text(result)).toContain('[sandbox: file access denied under workspace-write mode]')
+    expect(text(result)).toContain('retry this exact operation once with sandbox_permissions')
+  })
+
+  it('a non-FS_SANDBOX_DENIED provider error passes through unchanged', async () => {
+    const { ctx, fs } = await setupConfining()
+    fs.rejectWith = new FsError('boom', 'FS_IO_ERROR')
+    const result = await call(ctx, 'write', { file_path: 'a.txt', content: 'x' }, escalationAgent())
+    expect(result.isError).toBe(true)
+    expect(text(result)).toContain('boom')
+    expect(text(result)).not.toContain('[sandbox:')
+  })
+
+  it('an approved escalation stamps the granted mode onto that write', async () => {
+    const { ctx, fs } = await setupConfining({ approval: true })
+    ctx.on('approval/request', () => Promise.resolve('allowed-once' as const))
+    // Pass a signal so the escalation ask forwards it to the approval request
+    // (the request rides the tool-execution abort signal).
+    await ctx.tools.execute({
+      callId: CallId('call-fs-esc-grant'),
+      name: 'write',
+      arguments: { file_path: 'a.txt', content: 'x', sandbox_permissions: 'danger-full-access', justification: 'the test needs it' },
+      agent: escalationAgent() as never,
+      signal: new AbortController().signal,
+    })
+    expect(fs.stamped).toEqual(['danger-full-access'])
+  })
+
+  it('a rejected escalation fails closed with its own text and never mutates', async () => {
+    const { ctx, fs } = await setupConfining({ approval: true })
+    ctx.on('approval/request', () => Promise.resolve('rejected' as const))
+    const result = await call(ctx, 'edit', { file_path: 'a.txt', old_string: 'x', new_string: 'y', sandbox_permissions: 'danger-full-access', justification: 'the test needs it' }, escalationAgent())
+    expect(result.isError).toBe(true)
+    expect(text(result)).toContain('the user rejected escalating this operation to "danger-full-access"')
+    expect(fs.stamped).toEqual([])
+  })
+
+  it('escalation without an approval service fails closed', async () => {
+    const { ctx } = await setupConfining()
+    const result = await call(ctx, 'write', { file_path: 'a.txt', content: 'x', sandbox_permissions: 'danger-full-access', justification: 'why' }, escalationAgent())
+    expect(result.isError).toBe(true)
+    expect(text(result)).toContain('no approval service is composed')
+  })
+
+  it('escalation with an approval service but no agent fails closed', async () => {
+    const { ctx } = await setupConfining({ approval: true })
+    const result = await call(ctx, 'write', { file_path: 'a.txt', content: 'x', sandbox_permissions: 'danger-full-access', justification: 'why' })
+    expect(result.isError).toBe(true)
+    expect(text(result)).toContain('no agent to route it through')
+  })
+
+  it('rejects the escalation argument pairing (one field without the other)', async () => {
+    const { ctx } = await setupConfining()
+    const missing = await call(ctx, 'write', { file_path: 'a.txt', content: 'x', sandbox_permissions: 'workspace-write' }, escalationAgent())
+    expect(missing.isError).toBe(true)
+    expect(text(missing)).toContain('sandbox_permissions requires a justification')
+  })
+
+  it('sandbox_permissions under a non-confining backend fails closed (unadvertised field still reaches execute)', async () => {
+    const { ctx } = await setup()
+    const result = await call(ctx, 'write', { file_path: 'a.txt', content: 'x', sandbox_permissions: 'workspace-write', justification: 'why' }, escalationAgent())
+    expect(result.isError).toBe(true)
+    expect(text(result)).toContain('not available in this composition')
+  })
+})

packages/fs/tool-fs/tsconfig.json

@@ -13,6 +13,9 @@
     { "path": "../../core/tools" },
     { "path": "../../core/system-prompt" },
     { "path": "../fs" },
-    { "path": "../fs-policy" }
+    { "path": "../fs-policy" },
+    { "path": "../../sandbox/sandbox" },
+    { "path": "../../sandbox/sandbox-policy" },
+    { "path": "../../ui/user-approval" }
   ]
 }

packages/sandbox/README.md

@@ -1,12 +1,13 @@
 # sandbox/ — process-sandbox capability family
 
-The confinement half of the [capability-seam split](../../docs/rfc/implemented/architecture/2026-06-13-capability-seams.md): an abstract provider interface and platform backends. Consumers hand `ctx.sandbox` the exact argv they are about to spawn and spawn the returned (wrapped) argv instead; policy (`SandboxPolicy`: mode + workspace root) rides each call, so different consumers confine under different policies at the same instant. All **product** packages.
+The confinement half of the [capability-seam split](../../docs/rfc/implemented/architecture/2026-06-13-capability-seams.md): an abstract provider interface, platform backends, and the shared policy home. Consumers hand `ctx.sandbox` the exact argv they are about to spawn and spawn the returned (wrapped) argv instead; policy (`SandboxPolicy`: mode + workspace root) rides each call, so different consumers confine under different policies at the same instant. All **product** packages.
 
 | Package | Role | ctx key |
 |---|---|---|
-| `sandbox/` | Abstract process-sandbox seam (the `SandboxProvider` contract + the mode/enforcement/policy vocabulary) | `ctx.sandbox` |
+| `sandbox/` | Abstract process-sandbox seam (the `SandboxProvider` contract + the mode/enforcement/policy vocabulary) plus the shared ESCALATION kit (`approveEscalation`, the strictly-wider ladder, the denial/hint markers) and the `writableRoots` derivation every enforcement dialect shares | `ctx.sandbox` |
 | `sandbox-local/` | Local backends by platform chain: Linux `bwrap` else the `landlock-run` launcher (the npm-distributed [`node-addon-landlock-run`](https://www.npmjs.com/package/node-addon-landlock-run) family, built and released from its own repository), darwin `sandbox-exec`/Seatbelt — multi-candidate chains functionally probed, sole candidates selected directly, verdict cached, fail-closed | (registers `ctx.sandbox`) |
+| `sandbox-policy/` | The policy home: the deployment default (mode + `workspace-write` boundary root) and the per-session `sandbox/mode` override (event + fold + write path). Both enforcing families read it, so bash and fs can never confine to different roots | `ctx.sandboxPolicy` |
 
 The seam confines SAME-WORLD subprocesses only (shared filesystem and kernel). Containers, microVMs, and remote executors are NOT backends here — they replace whole capability implementations (`ctx.bash`, `ctx.fs`) as environment-coherent groups; the boundary is recorded in [the sandbox RFC](../../docs/rfc/implemented/feature/2026-07-06-sandbox.md).
 
-Consumers today: [`bash/bash-sandbox`](../bash/bash-sandbox/) (wraps `['bash', '-c', command]`; see [the acp-agent example's default composition](../../examples/acp-agent/) for the composed leaf). In-process tools (fs/web) cannot be confined by an OS wrapper — their sandbox semantics are policy at their own seams (the sandbox RFC's cross-family phase).
+Consumers today: [`bash/bash-sandbox`](../bash/bash-sandbox/) (wraps `['bash', '-c', command]` through `ctx.sandbox`) and [`fs/fs-sandbox`](../fs/fs-sandbox/) (an in-process path fence, not an argv wrapper — reads `ctx.sandboxPolicy` and enforces the shared mode on write/edit). The cross-family boundary is the sandbox RFC's [cross-family fs sandbox](../../docs/rfc/implemented/feature/2026-07-14-cross-family-fs-sandbox.md) phase; the shared vocabulary lets both families teach the model one denial marker and one escalation flow.

packages/sandbox/sandbox-policy/README.md

@@ -0,0 +1,23 @@
+# dsh-sandbox-policy — the sandbox policy home (`ctx.sandboxPolicy`)
+
+The single owner of the deployment's sandbox policy: the file-effect [`SandboxMode`](../sandbox/README.md) a session starts from, the `workspace-write` boundary root, and the per-session `sandbox/mode` override every enforcing capability family reads.
+
+## Why a shared home
+
+Two families enforce the same mode vocabulary: the sandboxed bash executor (`@deepseek-ai/dsh-bash-sandbox`) and the sandboxed filesystem provider (`@deepseek-ai/dsh-fs-sandbox`). If each held its own `mode` + `workspaceRoot` config, the two could drift into a split world — bash confined to one root while fs fences another, exactly what [the sandbox RFC](../../../docs/rfc/implemented/feature/2026-07-06-sandbox.md) warns against. Both inject `ctx.sandboxPolicy` and read the SAME default instead. The [cross-family fs sandbox RFC](../../../docs/rfc/implemented/feature/2026-07-14-cross-family-fs-sandbox.md) records the decision.
+
+## Config
+
+- `mode` — the deployment default `SandboxMode` (`read-only` / `workspace-write` / `danger-full-access`), validated at load. Default `read-only` (fail-safe).
+- `workspaceRoot` — the absolute directory `workspace-write` may write under. Default `process.cwd()`, resolved absolute either way.
+
+## Surface
+
+- `ctx.sandboxPolicy.defaultMode` / `ctx.sandboxPolicy.workspaceRoot` — the deployment default the enforcing implementations read for their resolve fallback and boundary.
+- `effectiveSandboxMode(events)` — the pure fold of a session's `sandbox/mode` events (the last switch wins, or `undefined`). The tool layers apply it to stamp each call, so neither the executor nor the provider depends on session events.
+- `setSandboxMode(session, mode)` — THE write path for a per-session override: appends exactly one `sandbox/mode` event. The switch IS its event; nothing mutates the mode out of band.
+- `SANDBOX_MODES` — every mode, for option advertisement and runtime validation.
+
+## The per-session store
+
+A runtime switch (an ACP `session/set_config_option`, a test scenario) is one log-only `sandbox/mode` event on the session it applies to. `effective = fold(events) ?? the deployment default`, so an override survives restart by replay, two sessions never see each other's state, and there is no external config store. The event is log-only (the `approval/*` precedent): the model learns the mode from the enforcing tools' denial markers, never from the event. Execution honors the fold in each tool layer, weakest-precedence beneath an escalation grant.

packages/sandbox/sandbox-policy/package.json

@@ -0,0 +1,37 @@
+{
+  "name": "@deepseek-ai/dsh-sandbox-policy",
+  "description": "Sandbox policy home (ctx.sandboxPolicy) for the DeepSeek Harness: the deployment default mode + workspace root and the per-session sandbox/mode override, shared by every enforcing capability family",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "main": "lib/index.js",
+  "types": "lib/types/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./lib/types/index.d.ts",
+      "default": "./lib/index.js"
+    },
+    "./src/*": "./src/*",
+    "./package.json": "./package.json"
+  },
+  "files": [
+    "lib/index.js",
+    "lib/types/**/*.d.ts",
+    "lib/types/**/*.d.ts.map",
+    "src"
+  ],
+  "license": "BSD-3-Clause",
+  "peerDependencies": {
+    "@deepseek-ai/dsh-sandbox": "^0.0.1",
+    "@deepseek-ai/dsh-session": "^0.0.1",
+    "cordis": "^4.0.0-rc.6"
+  },
+  "dependencies": {
+    "schemastery": "^3.18.0"
+  },
+  "devDependencies": {
+    "@deepseek-ai/dsh-sandbox": "workspace:^",
+    "@deepseek-ai/dsh-session": "workspace:^",
+    "cordis": "^4.0.0-rc.6"
+  }
+}

packages/sandbox/sandbox-policy/src/index.ts

@@ -0,0 +1,84 @@
+/**
+ * The sandbox POLICY home (`ctx.sandboxPolicy`): the single owner of the
+ * deployment's sandbox default — the file-effect {@link SandboxMode} a session
+ * starts from and the `workspace-write` boundary root — plus the per-session
+ * override kit (the `sandbox/mode` event, its fold, and its write path, from
+ * `./session-mode.ts`).
+ *
+ * Both enforcing capability families read the SAME policy here: the sandboxed
+ * bash executor (`@deepseek-ai/dsh-bash-sandbox`) and the sandboxed filesystem
+ * provider (`@deepseek-ai/dsh-fs-sandbox`) inject `ctx.sandboxPolicy` for the
+ * default mode and workspace root, so bash and fs can never confine to
+ * different roots — the split world the sandbox RFC warns about. The default
+ * lives here rather than on either executor's config precisely because it is
+ * one fact two families share.
+ *
+ * This service holds only the DEFAULT; the per-session fold
+ * ({@link effectiveSandboxMode}) is a pure function the tool layers apply to
+ * stamp each call, so neither the executor nor the provider depends on session
+ * events.
+ *
+ * @module @deepseek-ai/dsh-sandbox-policy
+ */
+
+import { resolve } from 'node:path'
+import { Context, Service } from 'cordis'
+import z from 'schemastery'
+import type { SandboxMode } from '@deepseek-ai/dsh-sandbox'
+
+export { SANDBOX_MODES, effectiveSandboxMode, setSandboxMode } from './session-mode.ts'
+
+declare module 'cordis' {
+  interface Context {
+    sandboxPolicy: SandboxPolicyService
+  }
+}
+
+/**
+ * Plugin config: the deployment's sandbox default. All optional — `Config`
+ * supplies the defaults (`mode: 'read-only'` is the fail-safe default; a
+ * deployment that wants a workspace-writable agent opts in explicitly). The
+ * runner choice is NOT here (it is the `ctx.sandbox` provider's config), nor
+ * is any per-family knob: this is the one shared policy home.
+ */
+export interface Config {
+  /** File-sandbox mode a session starts from (default: `read-only`). */
+  mode?: SandboxMode
+  /**
+   * Absolute root directory `workspace-write` may write under (default:
+   * `process.cwd()`). Both enforcing families fence against this SAME root.
+   */
+  workspaceRoot?: string
+}
+
+/**
+ * The sandbox-policy service (`ctx.sandboxPolicy`). Owns the deployment
+ * default mode and workspace root; enforcing implementations read
+ * {@link defaultMode} and {@link workspaceRoot}, and the tool layers fold each
+ * session's `sandbox/mode` override with {@link effectiveSandboxMode} on top.
+ */
+export class SandboxPolicyService extends Service {
+  // Inline schema call: the config catalog walks `static Config` statically.
+  static Config: z<Config> = z.object({
+    mode: z.union(['read-only', 'workspace-write', 'danger-full-access'] as const).default('read-only'),
+    // No schema default: process.cwd() is resolved in the constructor so the
+    // stored root is always absolute regardless of how it was supplied.
+    workspaceRoot: z.string(),
+  })
+
+  /** The deployment default mode — the fallback beneath a session override. */
+  readonly defaultMode: SandboxMode
+  /** The absolute `workspace-write` boundary root both families fence against. */
+  readonly workspaceRoot: string
+
+  constructor(ctx: Context, config: Config) {
+    super(ctx, 'sandboxPolicy')
+    // schemastery (static Config) already filled `mode`; the cast records that
+    // runtime fact. `workspaceRoot` has NO schema default, so its fallback to
+    // the process cwd is real branching, resolved absolute either way.
+    this.defaultMode = config.mode as SandboxMode
+    this.workspaceRoot = resolve(config.workspaceRoot ?? process.cwd())
+  }
+}
+
+export default SandboxPolicyService

packages/bash/bash/src/session-mode.ts → packages/sandbox/sandbox-policy/src/session-mode.ts

@@ -1,18 +1,21 @@
 /**
  * Per-session sandbox-mode override: the session log as the store. A runtime
  * switch (an ACP `session/set_config_option`, a test scenario) is recorded as
- * one `bash/sandbox-mode` event on the session it applies to;
- * `effective = fold(events) ?? the executor's configured default`, so an
- * override survives restart by replay, two sessions can never see each
- * other's state, and there is no external config store. The event is
- * log-only (the `approval/*` precedent): the model learns the mode from the
- * prompt section and the boundary notices in `@deepseek-ai/dsh-tool-bash`,
- * never from the event itself. EXECUTION honors the fold in the tool layer —
- * it stamps the effective mode onto each call's `BashExecRequest.sandboxMode`
- * (weakest-precedence: an escalation grant for the call outranks it) — the
- * executor itself stays a config-fixed default plus per-call overrides.
+ * one `sandbox/mode` event on the session it applies to;
+ * `effective = fold(events) ?? the deployment default`, so an override
+ * survives restart by replay, two sessions can never see each other's state,
+ * and there is no external config store. The event is log-only (the
+ * `approval/*` precedent): the model learns the mode from the boundary
+ * markers in the enforcing tools, never from the event itself. EXECUTION
+ * honors the fold in each tool layer — it stamps the effective mode onto the
+ * per-call policy carrier (a bash request's `sandboxMode`, an fs mutation's
+ * `sandboxMode`), weakest-precedence beneath an escalation grant.
  *
- * @module dsh-bash/session-mode
+ * The override is policy state shared by every enforcing family (bash and
+ * filesystem alike), so it lives here in the policy package rather than in any
+ * one capability's seam.
+ *
+ * @module dsh-sandbox-policy/session-mode
  */
 
 import type { Session, SessionEvent } from '@deepseek-ai/dsh-session'
@@ -28,7 +31,7 @@ declare module '@deepseek-ai/dsh-session' {
      * from position (an event after the log's last `request/header*` was a
      * runtime switch by the user; see the tool layer's narrator).
      */
-    'bash/sandbox-mode': { mode: SandboxMode }
+    'sandbox/mode': { mode: SandboxMode }
   }
 }
 
@@ -36,30 +39,30 @@ declare module '@deepseek-ai/dsh-session' {
 export const SANDBOX_MODES: readonly SandboxMode[] = ['read-only', 'workspace-write', 'danger-full-access']
 
 /**
- * The session's sandbox-mode override: the last `bash/sandbox-mode` event in
- * the log, or undefined when the session never switched (callers apply the
- * executor's configured default). The pure fold — resume needs no catch-up
- * machinery because replaying the log IS the state.
+ * The session's sandbox-mode override: the last `sandbox/mode` event in the
+ * log, or undefined when the session never switched (callers apply the
+ * deployment default). The pure fold — resume needs no catch-up machinery
+ * because replaying the log IS the state.
  * @param events - session events in log order (other event types are skipped).
  * @returns the mode of the last switch event, or undefined without one.
  */
 export function effectiveSandboxMode(events: readonly SessionEvent[]): SandboxMode | undefined {
   for (let index = events.length - 1; index >= 0; index -= 1) {
     const event = events[index] as SessionEvent
-    if (event.type === 'bash/sandbox-mode') return event.data.mode
+    if (event.type === 'sandbox/mode') return event.data.mode
   }
   return undefined
 }
 
 /**
  * THE write path for a session's sandbox-mode override: appends exactly one
- * `bash/sandbox-mode` event — the switch IS its event; nothing mutates mode
- * state out of band. Takes effect on the session's next bash call and next
- * prompt assembly (the consumers fold on every read).
+ * `sandbox/mode` event — the switch IS its event; nothing mutates mode state
+ * out of band. Takes effect on the session's next confined call (bash or fs)
+ * — the consumers fold on every read.
  * @param session - the session the override belongs to.
- * @param mode - the mode every subsequent bash call in this session runs
+ * @param mode - the mode every subsequent confined call in this session runs
  *   under (until the next switch).
  */
 export function setSandboxMode(session: Session, mode: SandboxMode): void {
-  session.append('bash/sandbox-mode', { mode })
+  session.append('sandbox/mode', { mode })
 }

packages/sandbox/sandbox-policy/tests/policy.spec.ts

@@ -0,0 +1,67 @@
+/**
+ * Tests for the sandbox-policy home: the deployment default (mode +
+ * workspaceRoot) the service exposes, and the per-session `sandbox/mode`
+ * override kit (fold + write path) both enforcing families read.
+ */
+
+import { resolve } from 'node:path'
+import { describe, expect, it } from 'vitest'
+import { Context } from 'cordis'
+import { Session, SessionId } from '@deepseek-ai/dsh-session'
+import SandboxPolicyService, { SANDBOX_MODES, effectiveSandboxMode, setSandboxMode } from '@deepseek-ai/dsh-sandbox-policy'
+
+async function mounted(config: { mode?: 'read-only' | 'workspace-write' | 'danger-full-access'; workspaceRoot?: string } = {}) {
+  const ctx = new Context()
+  await ctx.plugin(SandboxPolicyService, config)
+  return ctx
+}
+
+describe('SandboxPolicyService', () => {
+  it('defaults to read-only under the process cwd', async () => {
+    const ctx = await mounted()
+    expect(ctx.sandboxPolicy.defaultMode).toBe('read-only')
+    expect(ctx.sandboxPolicy.workspaceRoot).toBe(resolve(process.cwd()))
+  })
+
+  it('carries a configured mode and resolves the workspace root absolute', async () => {
+    const ctx = await mounted({ mode: 'workspace-write', workspaceRoot: '/ws/../ws/./sub' })
+    expect(ctx.sandboxPolicy.defaultMode).toBe('workspace-write')
+    expect(ctx.sandboxPolicy.workspaceRoot).toBe(resolve('/ws/../ws/./sub'))
+  })
+
+  it('rejects a mode outside the closed vocabulary at load', async () => {
+    const ctx = new Context()
+    // schemastery rejects the union violation when the plugin loads.
+    await expect(ctx.plugin(SandboxPolicyService, { mode: 'yolo' as never })).rejects.toThrow()
+  })
+
+  it('unregisters cleanly from a child fiber (HMR safety)', async () => {
+    const ctx = new Context()
+    const fiber = await ctx.plugin(SandboxPolicyService, {})
+    expect(ctx.sandboxPolicy).toBeDefined()
+    await fiber.dispose()
+    expect(ctx.get('sandboxPolicy')).toBeUndefined()
+  })
+})
+
+describe('the sandbox/mode session kit', () => {
+  it('SANDBOX_MODES lists every mode for advertisement and validation', () => {
+    expect(SANDBOX_MODES).toEqual(['read-only', 'workspace-write', 'danger-full-access'])
+  })
+
+  it('effectiveSandboxMode folds to the last switch, or undefined without one', () => {
+    const session = new Session(SessionId('sess-fold'))
+    expect(effectiveSandboxMode(session.events)).toBeUndefined()
+    setSandboxMode(session, 'workspace-write')
+    setSandboxMode(session, 'read-only')
+    expect(effectiveSandboxMode(session.events)).toBe('read-only')
+  })
+
+  it('setSandboxMode appends exactly one sandbox/mode event per switch', () => {
+    const session = new Session(SessionId('sess-write'))
+    setSandboxMode(session, 'danger-full-access')
+    const modeEvents = session.events.filter(e => e.type === 'sandbox/mode')
+    expect(modeEvents).toHaveLength(1)
+    expect(modeEvents[0]?.data).toEqual({ mode: 'danger-full-access' })
+  })
+})

packages/sandbox/sandbox-policy/tsconfig.json

@@ -0,0 +1,27 @@
+{
+  "extends": "../../../tsconfig.base.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "lib/types"
+  },
+  "include": [
+    "src"
+  ],
+  "references": [
+    {
+      "path": "../../../vendor/cosmokit"
+    },
+    {
+      "path": "../../../vendor/cordis"
+    },
+    {
+      "path": "../../../vendor/schemastery"
+    },
+    {
+      "path": "../sandbox"
+    },
+    {
+      "path": "../../core/session"
+    }
+  ]
+}

packages/sandbox/sandbox/src/escalation.ts

@@ -0,0 +1,189 @@
+/**
+ * The escalation vocabulary and choreography shared by every sandbox-enforcing
+ * tool family (`@deepseek-ai/dsh-tool-bash`, `@deepseek-ai/dsh-tool-fs`): the
+ * strictly-wider ladder, the argument-pairing validation, the model-facing
+ * denial/hint markers, and {@link approveEscalation} — the ordered fail-closed
+ * sequence that resolves a `sandbox_permissions` request through a
+ * user-approval channel BEFORE anything executes. One home keeps the two
+ * families' approval ordering and verbatim error texts from drifting apart.
+ *
+ * The channel is a minimal STRUCTURAL function shape ({@link EscalationAsk}),
+ * not the approval service type: the tool layer — which owns the agent, the
+ * call id, and the tool name — closes over `ctx.approval.request(...)` and
+ * hands the closure down, so this package never depends on the approval or
+ * agent packages.
+ *
+ * @module dsh-sandbox/escalation
+ */
+
+import { assertNever } from '@deepseek-ai/dsh-llm'
+import type { SandboxMode } from './index.ts'
+
+/**
+ * The strictly-wider table: what a call whose effective mode is the key may
+ * escalate TO. Checked at EXECUTION, never baked into a tool schema — the
+ * schema's enum is {@link ESCALATION_TARGETS}, because schemas are
+ * registry-global while the effective mode is per-call truth.
+ */
+export const WIDER_MODES: Record<string, readonly SandboxMode[]> = {
+  'read-only': ['workspace-write', 'danger-full-access'],
+  'workspace-write': ['danger-full-access'],
+}
+
+/**
+ * The closed escalation-target vocabulary — every mode a call could ever
+ * escalate TO (`read-only` is the floor; nothing escalates to it). Advertised
+ * whenever the mounted capability confines: cutting the enum down to the modes
+ * wider than the composition's DEFAULT would strand a session whose effective
+ * mode sits below it (a `danger-full-access` default would advertise nothing
+ * while a narrower-switched session stays confined with no lever).
+ */
+export const ESCALATION_TARGETS: readonly SandboxMode[] = ['workspace-write', 'danger-full-access']
+
+/**
+ * Validate the escalation argument pairing a tool schema cannot express:
+ * `sandbox_permissions` and `justification` travel together — an approval
+ * prompt without a reason, or a reason driving nothing, is a malformed ask —
+ * and the justification must be a non-empty sentence.
+ * @param sandboxPermissions - the raw `sandbox_permissions` argument, if given.
+ * @param justification - the raw `justification` argument, if given.
+ */
+export function validateEscalationArgs(sandboxPermissions: string | undefined, justification: string | undefined): void {
+  if (sandboxPermissions !== undefined && justification === undefined) {
+    throw new Error('invalid escalation: sandbox_permissions requires a justification')
+  }
+  if (justification !== undefined && sandboxPermissions === undefined) {
+    throw new Error('invalid escalation: justification is only valid together with sandbox_permissions')
+  }
+  if (justification !== undefined && justification.trim().length === 0) {
+    throw new Error('invalid justification: expected a non-empty sentence')
+  }
+}
+
+/**
+ * The model-facing denial marker — the one vocabulary both enforcing families
+ * teach and report, so the model recognizes a policy denial identically
+ * whether the kernel refused a bash file effect or the filesystem provider's
+ * fence refused a mutation.
+ * @param mode - the mode the denied call ran under.
+ * @returns the marker line, exactly as the model sees it.
+ */
+export function sandboxDenialMarker(mode: SandboxMode): string {
+  return `[sandbox: file access denied under ${mode} mode]`
+}
+
+/**
+ * The same-turn escalation hint that rides a denial when the composition
+ * advertises the escalation fields — the nudge lives at the decision point so
+ * the sanctioned retry does not depend on the model recalling the tool
+ * description.
+ * @param subject - the family's noun for the denied action (`command` for
+ *   bash, `operation` for a filesystem mutation).
+ * @returns the hint line, exactly as the model sees it.
+ */
+export function escalationHintMarker(subject: string): string {
+  return `[sandbox: escalation available — retry this exact ${subject} once with sandbox_permissions (the narrowest wider mode that suffices) + justification; the approval prompt asks the user]`
+}
+
+/**
+ * The closed outcome vocabulary of one escalation ask — structurally identical
+ * to the approval seam's `ApprovalOutcome` so an `ApprovalService.request`
+ * return is assignable without this package importing it.
+ */
+export type EscalationOutcome = 'allowed-once' | 'rejected' | 'cancelled' | 'unavailable'
+
+/**
+ * The minimal approval-request shape {@link approveEscalation} needs —
+ * structurally the approval seam's `ApprovalService`, generic over the agent
+ * type `A` and call-id type `C` so this package resolves escalations through
+ * `ctx.approval` without importing the approval or agent packages (the tool
+ * layer infers `A`/`C` as its own `Agent`/`CallId`).
+ */
+export interface EscalationApprover<A = object, C = string> {
+  /**
+   * Ask the human to approve one action, resolving to a closed outcome.
+   * @param req - the audit-self-contained request (agent, tool, call id, reason, optional signal).
+   * @returns the human's decision as a closed {@link EscalationOutcome}.
+   */
+  request(req: { agent: A; toolName: string; callId: C; reason: string; signal?: AbortSignal }): Promise<EscalationOutcome>
+}
+
+/**
+ * The approval ingredients an escalating tool hands {@link approveEscalation}:
+ * the approval requester (`ctx.approval`, or `undefined` when none is
+ * composed), the calling agent (or `undefined` for an agent-less execution),
+ * and the call's identity. The tool layer holds all of these; this package
+ * only judges them.
+ */
+export interface EscalationApproval<A = object, C = string> {
+  /** The approval requester (`ctx.approval`), or `undefined` when none is composed. */
+  approver: EscalationApprover<A, C> | undefined
+  /** The calling agent, or `undefined` for an agent-less execution (fails closed). */
+  agent: A | undefined
+  /** The tool-call id the approval prompt attaches to. */
+  callId: C
+  /** The tool name recorded on the approval request. */
+  toolName: string
+  /** The tool-execution abort signal the approval request rides, when present. */
+  signal?: AbortSignal
+}
+
+/** One escalation request, as {@link approveEscalation} judges it. */
+export interface EscalationRequest {
+  /** The requested target mode (schema-pinned to {@link ESCALATION_TARGETS} when advertised). */
+  requestedMode: string
+  /** The model's one-sentence reason, shown verbatim to the user inside the audit reason. */
+  justification: string
+  /** The call's effective mode (session override ?? composition default) the request must strictly widen. */
+  effectiveMode: SandboxMode
+  /** The family's noun for the escalated action in user-facing texts (`command` for bash, `operation` for fs). */
+  subject: string
+}
+
+/**
+ * Resolve a sandbox-escalation request BEFORE anything executes: check strict
+ * widening against the call's effective mode, then resolve the approval
+ * channel, then map every outcome — the ordered fail-closed sequence both
+ * enforcing families share. Returns the granted mode to stamp onto exactly
+ * this call; throws the distinct verbatim text for every other path (a
+ * non-widening request, a missing approval service, an agent-less execution,
+ * a rejection, a cancellation, an unanswerable ask) — the tool registry turns
+ * the throw into the call's isError result, and nothing has run. A
+ * non-widening request never prompts a human.
+ * @param request - the escalation to judge (see {@link EscalationRequest}).
+ * @param approval - the approval ingredients the tool holds (see {@link EscalationApproval}).
+ * @returns the granted mode, consumed by the one call that asked.
+ */
+export async function approveEscalation<A, C>(request: EscalationRequest, approval: EscalationApproval<A, C>): Promise<SandboxMode> {
+  const { requestedMode: mode, effectiveMode, justification, subject } = request
+  // Strict widening is an EXECUTION check against the call's effective mode —
+  // deliberately not a schema constraint (the enum is the closed target
+  // vocabulary; the effective mode is per-call truth).
+  if (!(WIDER_MODES[effectiveMode] ?? []).includes(mode as SandboxMode)) {
+    throw new Error(`sandbox escalation to "${mode}" is not strictly wider than this call's current "${effectiveMode}" mode`)
+  }
+  if (approval.approver === undefined) {
+    throw new Error(`sandbox escalation to "${mode}" requires approval, but no approval service is composed`)
+  }
+  if (approval.agent === undefined) {
+    throw new Error(`sandbox escalation to "${mode}" requires approval, but the call has no agent to route it through`)
+  }
+  // Self-contained for the audit trail: approval/asked stores this reason,
+  // and the target mode is part of the grant's identity.
+  const outcome = await approval.approver.request({
+    agent: approval.agent,
+    toolName: approval.toolName,
+    callId: approval.callId,
+    reason: `escalate sandbox to ${mode}: ${justification}`,
+    ...approval.signal ? { signal: approval.signal } : {},
+  })
+  switch (outcome) {
+    // The schema enum already pinned `mode` to the closed target vocabulary;
+    // the check above proved it is strictly wider.
+    case 'allowed-once': return mode as SandboxMode
+    case 'rejected': throw new Error(`the user rejected escalating this ${subject} to "${mode}"`)
+    case 'cancelled': throw new Error(`approval for escalating to "${mode}" was cancelled`)
+    case 'unavailable': throw new Error(`sandbox escalation to "${mode}" requires approval, but no approval channel is available`)
+    default: return assertNever(outcome, 'EscalationOutcome')
+  }
+}

packages/sandbox/sandbox/src/index.ts

@@ -25,6 +25,17 @@
 import { Context, Service } from 'cordis'
 import { HarnessError } from '@deepseek-ai/dsh-llm'
 
+export {
+  ESCALATION_TARGETS,
+  WIDER_MODES,
+  approveEscalation,
+  escalationHintMarker,
+  sandboxDenialMarker,
+  validateEscalationArgs,
+} from './escalation.ts'
+export type { EscalationApproval, EscalationApprover, EscalationOutcome, EscalationRequest } from './escalation.ts'
+export { canonicalPath, writableRoots } from './roots.ts'
+
 /**
  * File-effect policy a sandbox backend enforces on confined processes.
  *

packages/sandbox/sandbox/src/roots.ts

@@ -0,0 +1,51 @@
+/**
+ * The writable-root derivation shared by every enforcement dialect that
+ * expresses a mode as a canonical allow-list: `workspace-write` means "the
+ * workspace root plus the platform temp areas", and this module is that
+ * meaning's one home. The Seatbelt profile
+ * (`@deepseek-ai/dsh-sandbox-local`) and the in-process filesystem fence
+ * (`@deepseek-ai/dsh-fs-sandbox`) both derive their allow-list here, so "the
+ * write tool cannot write /tmp but bash can" asymmetries cannot arise between
+ * them. The bwrap and Landlock dialects keep their own grant spellings (an
+ * ephemeral `/tmp` mount, launcher-owned flags) — the honest per-runner
+ * differences recorded in the sandbox RFC — with parity pinned by test.
+ *
+ * @module dsh-sandbox/roots
+ */
+
+import { realpathSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import type { SandboxPolicy } from './index.ts'
+
+/**
+ * Resolve a granted root to the path the enforcement layer actually compares:
+ * canonical (symlinks resolved), because both Seatbelt filters and the fs
+ * fence's containment check match resolved paths — `/tmp` IS `/private/tmp`
+ * on darwin, and an as-spelled grant would match nothing.
+ * @param path - the root as configured or platform-reported.
+ * @returns the canonical path, or the spelling as-is when resolution fails
+ *   (a missing root matches nothing until it exists — the conservative
+ *   outcome; inventing a fallback would grant a path the caller never named).
+ */
+export function canonicalPath(path: string): string {
+  try {
+    return realpathSync(path)
+  } catch {
+    // realpathSync failed: the path (or a prefix) is missing or unreadable.
+    return path
+  }
+}
+
+/**
+ * The roots one confined execution may WRITE under — the mode's meaning as a
+ * canonical, deduplicated allow-list. `read-only` allows nothing;
+ * `workspace-write` allows the policy's workspace root, the host `/tmp`, and
+ * the per-user platform temp dir (`os.tmpdir()` — the real temp area for
+ * mkstemp-family tools; omitting it would deny what the mode promises).
+ * @param policy - the file-effect policy to derive the allow-list from.
+ * @returns the canonical writable roots; empty exactly under `read-only`.
+ */
+export function writableRoots(policy: SandboxPolicy): string[] {
+  if (policy.mode !== 'workspace-write') return []
+  return [...new Set([policy.workspaceRoot, '/tmp', tmpdir()].map(canonicalPath))]
+}

packages/sandbox/sandbox/tests/escalation.spec.ts

@@ -0,0 +1,111 @@
+/**
+ * Tests for the shared escalation vocabulary and choreography: the strictly-
+ * wider ladder, the argument-pairing validation, the model-facing markers, and
+ * {@link approveEscalation}'s ordered fail-closed sequence. Both enforcing tool
+ * families (`dsh-tool-bash`, `dsh-tool-fs`) delegate here, so the ordering and
+ * verbatim texts are pinned once, next to the vocabulary that owns them.
+ */
+
+import { describe, expect, it } from 'vitest'
+import {
+  ESCALATION_TARGETS,
+  WIDER_MODES,
+  approveEscalation,
+  escalationHintMarker,
+  sandboxDenialMarker,
+  validateEscalationArgs,
+} from '@deepseek-ai/dsh-sandbox'
+import type { EscalationApprover, EscalationOutcome } from '@deepseek-ai/dsh-sandbox'
+
+describe('the strictly-wider ladder', () => {
+  it('read-only escalates to either wider mode; workspace-write only to full access', () => {
+    expect(WIDER_MODES['read-only']).toEqual(['workspace-write', 'danger-full-access'])
+    expect(WIDER_MODES['workspace-write']).toEqual(['danger-full-access'])
+    expect(WIDER_MODES['danger-full-access']).toBeUndefined()
+  })
+
+  it('the target enum is the closed set every session could escalate TO (read-only is the floor)', () => {
+    expect(ESCALATION_TARGETS).toEqual(['workspace-write', 'danger-full-access'])
+  })
+})
+
+describe('validateEscalationArgs', () => {
+  it('accepts neither field, or both with a non-empty justification', () => {
+    expect(() => { validateEscalationArgs(undefined, undefined) }).not.toThrow()
+    expect(() => { validateEscalationArgs('workspace-write', 'because the workspace needs it') }).not.toThrow()
+  })
+
+  it('rejects one field without the other, and a blank justification', () => {
+    expect(() => { validateEscalationArgs('workspace-write', undefined) }).toThrow(/requires a justification/)
+    expect(() => { validateEscalationArgs(undefined, 'orphan reason') }).toThrow(/only valid together with sandbox_permissions/)
+    expect(() => { validateEscalationArgs('workspace-write', '   ') }).toThrow(/non-empty sentence/)
+  })
+})
+
+describe('the model-facing markers', () => {
+  it('the denial marker names the mode', () => {
+    expect(sandboxDenialMarker('read-only')).toBe('[sandbox: file access denied under read-only mode]')
+    expect(sandboxDenialMarker('workspace-write')).toBe('[sandbox: file access denied under workspace-write mode]')
+  })
+
+  it('the hint marker names the family subject', () => {
+    expect(escalationHintMarker('command')).toContain('retry this exact command once with sandbox_permissions')
+    expect(escalationHintMarker('operation')).toContain('retry this exact operation once with sandbox_permissions')
+  })
+})
+
+describe('approveEscalation', () => {
+  const req = (over: Partial<Parameters<typeof approveEscalation>[0]> = {}) => ({
+    requestedMode: 'workspace-write',
+    justification: 'the user asked to write in the workspace',
+    effectiveMode: 'read-only' as const,
+    subject: 'command',
+    ...over,
+  })
+  /** An approver that records the request and returns a fixed outcome. */
+  const approver = (outcome: EscalationOutcome, sink?: (req: unknown) => void): EscalationApprover => ({
+    request: async (request) => { sink?.(request); return outcome },
+  })
+  const ingredients = (over: Partial<Parameters<typeof approveEscalation>[1]> = {}) => ({
+    approver: approver('allowed-once'),
+    agent: {},
+    callId: 'call-1',
+    toolName: 'bash',
+    ...over,
+  })
+
+  it('grants: returns the requested mode, asking through the approver with the audit reason', async () => {
+    const seen: { reason?: string }[] = []
+    const granted = await approveEscalation(req(), ingredients({ approver: approver('allowed-once', r => seen.push(r as { reason?: string })) }))
+    expect(granted).toBe('workspace-write')
+    expect(seen[0]?.reason).toBe('escalate sandbox to workspace-write: the user asked to write in the workspace')
+  })
+
+  it('a non-widening request fails closed with its own text and never asks', async () => {
+    const seen: unknown[] = []
+    const spy = ingredients({ approver: approver('allowed-once', r => seen.push(r)) })
+    await expect(approveEscalation(req({ requestedMode: 'read-only' }), spy))
+      .rejects.toThrow(/not strictly wider than this call's current "read-only" mode/)
+    await expect(approveEscalation(req({ requestedMode: 'workspace-write', effectiveMode: 'danger-full-access' as never }), spy))
+      .rejects.toThrow(/not strictly wider/)
+    expect(seen).toEqual([])
+  })
+
+  it('a missing approval service and an agent-less call each fail closed with distinct text', async () => {
+    await expect(approveEscalation(req(), ingredients({ approver: undefined }))).rejects.toThrow(/no approval service is composed/)
+    await expect(approveEscalation(req(), ingredients({ agent: undefined }))).rejects.toThrow(/no agent to route it through/)
+  })
+
+  it('maps each non-grant outcome to its distinct verbatim text (subject in the rejection)', async () => {
+    await expect(approveEscalation(req({ subject: 'operation' }), ingredients({ approver: approver('rejected') })))
+      .rejects.toThrow('the user rejected escalating this operation to "workspace-write"')
+    await expect(approveEscalation(req(), ingredients({ approver: approver('cancelled') })))
+      .rejects.toThrow('approval for escalating to "workspace-write" was cancelled')
+    await expect(approveEscalation(req(), ingredients({ approver: approver('unavailable') })))
+      .rejects.toThrow('no approval channel is available')
+  })
+
+  it('an outcome outside the closed union trips the exhaustiveness guard (defensive)', async () => {
+    await expect(approveEscalation(req(), ingredients({ approver: approver('bogus' as never) }))).rejects.toThrow()
+  })
+})

packages/sandbox/sandbox/tests/roots.spec.ts

@@ -0,0 +1,39 @@
+/**
+ * Tests for the writable-root derivation: the mode's meaning as a canonical
+ * allow-list. Pinned here so the fs fence and the Seatbelt profile — both
+ * deriving from `writableRoots` — cannot drift.
+ */
+
+import { realpathSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { mkdtempSync } from 'node:fs'
+import { join } from 'node:path'
+import { describe, expect, it } from 'vitest'
+import { canonicalPath, writableRoots } from '@deepseek-ai/dsh-sandbox'
+
+describe('canonicalPath', () => {
+  it('resolves symlinks (an existing path realpaths)', () => {
+    const dir = mkdtempSync(join(tmpdir(), 'dsh-roots-'))
+    expect(canonicalPath(dir)).toBe(realpathSync(dir))
+  })
+
+  it('returns the spelling as-is when the path cannot be resolved (conservative — matches nothing until it exists)', () => {
+    expect(canonicalPath('/does/not/exist/anywhere-xyz')).toBe('/does/not/exist/anywhere-xyz')
+  })
+})
+
+describe('writableRoots', () => {
+  it('read-only grants nothing', () => {
+    expect(writableRoots({ mode: 'read-only', workspaceRoot: process.cwd() })).toEqual([])
+  })
+
+  it('workspace-write grants the workspace root plus the platform temp areas, canonical and deduplicated', () => {
+    const ws = mkdtempSync(join(tmpdir(), 'dsh-ws-'))
+    const roots = writableRoots({ mode: 'workspace-write', workspaceRoot: ws })
+    expect(roots).toContain(realpathSync(ws))
+    expect(roots).toContain(canonicalPath('/tmp'))
+    expect(roots).toContain(realpathSync(tmpdir()))
+    // Deduplicated after canonicalization (/tmp and os.tmpdir() may coincide).
+    expect(new Set(roots).size).toBe(roots.length)
+  })
+})

packages/ui/acp/tests/config-options.spec.ts

@@ -99,12 +99,12 @@ describe('acp bridge — session config options', () => {
 
     // Idle: nothing in the log yet — turn-enclosure forbids a bare append.
     const session = h.ctx.agents.list()[0]?.session
-    expect(session?.events.some(e => e.type === 'permission/preset' || e.type === 'bash/sandbox-mode' || e.type === 'approval/policy')).toBe(false)
+    expect(session?.events.some(e => e.type === 'permission/preset' || e.type === 'sandbox/mode' || e.type === 'approval/policy')).toBe(false)
 
     await h.client.prompt({ sessionId, prompt: [{ type: 'text', text: 'anchor' }] })
     const events = session?.events ?? []
     expect(events.filter(e => e.type === 'permission/preset').map(e => e.data)).toEqual([{ preset: 'danger-full-access' }])
-    expect(events.filter(e => e.type === 'bash/sandbox-mode').map(e => e.data)).toEqual([{ mode: 'danger-full-access' }])
+    expect(events.filter(e => e.type === 'sandbox/mode').map(e => e.data)).toEqual([{ mode: 'danger-full-access' }])
     expect(events.filter(e => e.type === 'approval/policy').map(e => e.data)).toEqual([{ policy: 'never' }])
     const turnStart = events.findIndex(e => e.type === 'turn/start')
     const anchored = events.findIndex(e => e.type === 'permission/preset')
@@ -135,7 +135,7 @@ describe('acp bridge — session config options', () => {
     expect(back.configOptions).toEqual([permissionOption('workspace-write')])
     await h.client.prompt({ sessionId, prompt: [{ type: 'text', text: 'anchor' }] })
     const events = h.ctx.agents.list()[0]?.session.events ?? []
-    expect(events.some(e => e.type === 'permission/preset' || e.type === 'bash/sandbox-mode' || e.type === 'approval/policy')).toBe(false)
+    expect(events.some(e => e.type === 'permission/preset' || e.type === 'sandbox/mode' || e.type === 'approval/policy')).toBe(false)
   })
 
   it('a no-op switch (the value already shown) records nothing and keeps a live pending', async () => {
@@ -163,7 +163,7 @@ describe('acp bridge — session config options', () => {
     const anchored = events.findIndex(e => e.type === 'permission/preset')
     expect(turnStart).toBeGreaterThanOrEqual(0)
     expect(anchored).toBeGreaterThan(turnStart)
-    expect(events.some(e => e.type === 'bash/sandbox-mode')).toBe(true)
+    expect(events.some(e => e.type === 'sandbox/mode')).toBe(true)
     expect(events.some(e => e.type === 'approval/policy')).toBe(true)
     await h.client.cancel({ sessionId })
     await hung
@@ -213,7 +213,7 @@ describe('acp bridge — session config options', () => {
     const agent = h.ctx.agents.list()[0]
     if (agent === undefined) throw new Error('expected an agent')
     agent.session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
-    agent.session.append('bash/sandbox-mode', { mode: 'read-only' })
+    agent.session.append('sandbox/mode', { mode: 'read-only' })
     agent.session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
     // The echo of the derived current is a no-op, not an unknown-value error…
     const echo = await h.client.setSessionConfigOption({ sessionId, configId: 'permission', value: 'custom' })

packages/ui/permission/package.json

@@ -24,6 +24,7 @@
   "peerDependencies": {
     "@deepseek-ai/dsh-bash": "^0.0.1",
     "@deepseek-ai/dsh-sandbox": "^0.0.1",
+    "@deepseek-ai/dsh-sandbox-policy": "^0.0.1",
     "@deepseek-ai/dsh-session": "^0.0.1",
     "@deepseek-ai/dsh-user-approval": "^0.0.1",
     "cordis": "^4.0.0-rc.6"
@@ -34,6 +35,7 @@
   "devDependencies": {
     "@deepseek-ai/dsh-bash": "workspace:^",
     "@deepseek-ai/dsh-sandbox": "workspace:^",
+    "@deepseek-ai/dsh-sandbox-policy": "workspace:^",
     "@deepseek-ai/dsh-session": "workspace:^",
     "@deepseek-ai/dsh-user-approval": "workspace:^",
     "cordis": "^4.0.0-rc.6"

packages/ui/permission/src/index.ts

@@ -1,7 +1,7 @@
 /**
  * User-facing PERMISSION PRESETS: one product-level knob over the two
  * mechanism knobs. A preset names a bundle — its sandbox mode
- * (`bash/sandbox-mode`) and its approval policy (`approval/policy`) — so a
+ * (`sandbox/mode`) and its approval policy (`approval/policy`) — so a
  * user picks `workspace-write` or `danger-full-access` while the mechanism
  * tiers stay orthogonal capabilities. Switching a preset WRITES THROUGH: one `permission/preset` event
  * records the chosen bundle (the audit fact reverse-mapping cannot recover —
@@ -19,7 +19,10 @@ import { Context, Service } from 'cordis'
 import z from 'schemastery'
 import type { Session, SessionEvent } from '@deepseek-ai/dsh-session'
 import type { SandboxMode } from '@deepseek-ai/dsh-sandbox'
-import { SANDBOX_MODES, effectiveSandboxMode, setSandboxMode } from '@deepseek-ai/dsh-bash'
+import { SANDBOX_MODES, effectiveSandboxMode, setSandboxMode } from '@deepseek-ai/dsh-sandbox-policy'
+// Side-effect type import: declaration-merges `ctx.bash` (the capability fact
+// `sandboxMode` this service reads), without a value dependency on the seam.
+import type {} from '@deepseek-ai/dsh-bash'
 import type { ApprovalPolicy } from '@deepseek-ai/dsh-user-approval'
 import { APPROVAL_POLICIES, effectiveApprovalPolicy, setApprovalPolicy } from '@deepseek-ai/dsh-user-approval'
 
@@ -33,7 +36,7 @@ declare module '@deepseek-ai/dsh-session' {
   interface SessionEventMap {
     /**
      * The session's permission preset was switched — log-only (the
-     * `bash/sandbox-mode` precedent): durable and replayable, never in the
+     * `sandbox/mode` precedent): durable and replayable, never in the
      * model transcript. The LAST such event is the session's preset
      * ({@link effectivePermissionPreset}); the knob events the switch wrote
      * through follow it in the same turn, and they — not this record of the
@@ -48,7 +51,7 @@ declare module '@deepseek-ai/dsh-session' {
  * runs under while the preset is active — plus its presentation.
  */
 export interface PresetSpec {
-  /** The `bash/sandbox-mode` value the preset writes through. */
+  /** The `sandbox/mode` value the preset writes through. */
   sandbox: SandboxMode
   /** The `approval/policy` value the preset writes through. */
   approval: ApprovalPolicy

packages/ui/permission/tests/permission.spec.ts

@@ -53,7 +53,7 @@ describe('PermissionService', () => {
   it('a knob state matching no table entry derives custom — a state, not an error', async () => {
     const ctx = await mounted()
     const session = freshSession('sess-custom')
-    session.append('bash/sandbox-mode', { mode: 'read-only' })
+    session.append('sandbox/mode', { mode: 'read-only' })
     expect(ctx.permission.current(session.events)).toBe(CUSTOM_PRESET)
     // Switching FROM custom is an ordinary write-through; custom itself is
     // never a target.
@@ -80,7 +80,7 @@ describe('PermissionService', () => {
     expect(ctx.permission.current(session.events)).toBe('agentish')
     // A knob drifts: the fold's bundle no longer matches → reverse map wins.
     session.append('approval/policy', { policy: 'never' })
-    session.append('bash/sandbox-mode', { mode: 'danger-full-access' })
+    session.append('sandbox/mode', { mode: 'danger-full-access' })
     expect(ctx.permission.current(session.events)).toBe('danger-full-access')
   })
 
@@ -90,7 +90,7 @@ describe('PermissionService', () => {
     ctx.permission.set(session, 'danger-full-access')
     expect(session.events.map(e => [e.type, e.data])).toEqual([
       ['permission/preset', { preset: 'danger-full-access' }],
-      ['bash/sandbox-mode', { mode: 'danger-full-access' }],
+      ['sandbox/mode', { mode: 'danger-full-access' }],
       ['approval/policy', { policy: 'never' }],
     ])
   })
@@ -109,12 +109,12 @@ describe('PermissionService', () => {
     // A knob drifts out from under the preset (a direct setter call, a test
     // scenario): the session derives custom, and re-asserting the preset is
     // a real switch again — choice re-recorded, only the drifted knob moves.
-    session.append('bash/sandbox-mode', { mode: 'read-only' })
+    session.append('sandbox/mode', { mode: 'read-only' })
     ctx.permission.set(session, 'danger-full-access')
     const tail = session.events.slice(4)
     expect(tail.map(e => [e.type, e.data])).toEqual([
       ['permission/preset', { preset: 'danger-full-access' }],
-      ['bash/sandbox-mode', { mode: 'danger-full-access' }],
+      ['sandbox/mode', { mode: 'danger-full-access' }],
     ])
   })
 

packages/ui/permission/tsconfig.json

@@ -23,6 +23,9 @@
     {
       "path": "../../sandbox/sandbox"
     },
+    {
+      "path": "../../sandbox/sandbox-policy"
+    },
     {
       "path": "../../bash/bash"
     },

pnpm-lock.yaml

@@ -89,9 +89,6 @@ importers:
       '@deepseek-ai/dsh-sandbox':
         specifier: workspace:^
         version: link:../../sandbox/sandbox
-      '@deepseek-ai/dsh-session':
-        specifier: workspace:^
-        version: link:../../core/session
       cordis:
         specifier: ^4.0.0-rc.6
         version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
@@ -113,10 +110,6 @@ importers:
         version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
 
   packages/bash/bash-sandbox:
-    dependencies:
-      schemastery:
-        specifier: ^3.18.0
-        version: 3.18.0
     devDependencies:
       '@deepseek-ai/dsh-bash':
         specifier: workspace:^
@@ -130,6 +123,9 @@ importers:
       '@deepseek-ai/dsh-sandbox-local':
         specifier: workspace:^
         version: link:../../sandbox/sandbox-local
+      '@deepseek-ai/dsh-sandbox-policy':
+        specifier: workspace:^
+        version: link:../../sandbox/sandbox-policy
       cordis:
         specifier: ^4.0.0-rc.6
         version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
@@ -163,6 +159,9 @@ importers:
       '@deepseek-ai/dsh-sandbox-local':
         specifier: workspace:^
         version: link:../../sandbox/sandbox-local
+      '@deepseek-ai/dsh-sandbox-policy':
+        specifier: workspace:^
+        version: link:../../sandbox/sandbox-policy
       '@deepseek-ai/dsh-session':
         specifier: workspace:^
         version: link:../../core/session
@@ -457,6 +456,9 @@ importers:
       '@deepseek-ai/dsh-llm':
         specifier: workspace:^
         version: link:../../llm/llm
+      '@deepseek-ai/dsh-sandbox':
+        specifier: workspace:^
+        version: link:../../sandbox/sandbox
       cordis:
         specifier: ^4.0.0-rc.6
         version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
@@ -489,6 +491,24 @@ importers:
         specifier: ^4.0.0-rc.6
         version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
 
+  packages/fs/fs-sandbox:
+    devDependencies:
+      '@deepseek-ai/dsh-fs':
+        specifier: workspace:^
+        version: link:../fs
+      '@deepseek-ai/dsh-fs-local':
+        specifier: workspace:^
+        version: link:../fs-local
+      '@deepseek-ai/dsh-sandbox':
+        specifier: workspace:^
+        version: link:../../sandbox/sandbox
+      '@deepseek-ai/dsh-sandbox-policy':
+        specifier: workspace:^
+        version: link:../../sandbox/sandbox-policy
+      cordis:
+        specifier: ^4.0.0-rc.6
+        version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
+
   packages/fs/tool-fs:
     dependencies:
       diff:
@@ -519,6 +539,12 @@ importers:
       '@deepseek-ai/dsh-llm-deepseek':
         specifier: workspace:^
         version: link:../../llm/llm-deepseek
+      '@deepseek-ai/dsh-sandbox':
+        specifier: workspace:^
+        version: link:../../sandbox/sandbox
+      '@deepseek-ai/dsh-sandbox-policy':
+        specifier: workspace:^
+        version: link:../../sandbox/sandbox-policy
       '@deepseek-ai/dsh-session':
         specifier: workspace:^
         version: link:../../core/session
@@ -528,6 +554,9 @@ importers:
       '@deepseek-ai/dsh-tools':
         specifier: workspace:^
         version: link:../../core/tools
+      '@deepseek-ai/dsh-user-approval':
+        specifier: workspace:^
+        version: link:../../ui/user-approval
       cordis:
         specifier: ^4.0.0-rc.6
         version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
@@ -718,6 +747,22 @@ importers:
         specifier: ^4.0.0-rc.6
         version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
 
+  packages/sandbox/sandbox-policy:
+    dependencies:
+      schemastery:
+        specifier: ^3.18.0
+        version: 3.18.0
+    devDependencies:
+      '@deepseek-ai/dsh-sandbox':
+        specifier: workspace:^
+        version: link:../sandbox
+      '@deepseek-ai/dsh-session':
+        specifier: workspace:^
+        version: link:../../core/session
+      cordis:
+        specifier: ^4.0.0-rc.6
+        version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
+
   packages/session-persistence/session-persistence:
     devDependencies:
       '@deepseek-ai/dsh-session':
@@ -1280,28 +1325,6 @@ importers:
         specifier: ^4.0.0-rc.6
         version: 4.0.0-rc.6(@cordisjs/plugin-include@vendor+include)(@cordisjs/plugin-loader@vendor+loader)
 
-  packages/ui/permission:
-    dependencies:
-      schemastery:
-        specifier: ^3.18.0
-        version: 3.18.0
-    devDependencies:
-      '@deepseek-ai/dsh-bash':
-        specifier: workspace:^
-        version: link:../../bash/bash
-      '@deepseek-ai/dsh-sandbox':
-        specifier: workspace:^
-        version: link:../../sandbox/sandbox
-      '@deepseek-ai/dsh-session':
-        specifier: workspace:^
-        version: link:../../core/session
-      '@deepseek-ai/dsh-user-approval':
-        specifier: workspace:^
-        version: link:../user-approval
-      cordis:
-        specifier: ^4.0.0-rc.6
-        version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
-
   packages/ui/jsonrpc:
     dependencies:
       schemastery:
@@ -1346,6 +1369,31 @@ importers:
         specifier: ^4.0.0-rc.6
         version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
 
+  packages/ui/permission:
+    dependencies:
+      schemastery:
+        specifier: ^3.18.0
+        version: 3.18.0
+    devDependencies:
+      '@deepseek-ai/dsh-bash':
+        specifier: workspace:^
+        version: link:../../bash/bash
+      '@deepseek-ai/dsh-sandbox':
+        specifier: workspace:^
+        version: link:../../sandbox/sandbox
+      '@deepseek-ai/dsh-sandbox-policy':
+        specifier: workspace:^
+        version: link:../../sandbox/sandbox-policy
+      '@deepseek-ai/dsh-session':
+        specifier: workspace:^
+        version: link:../../core/session
+      '@deepseek-ai/dsh-user-approval':
+        specifier: workspace:^
+        version: link:../user-approval
+      cordis:
+        specifier: ^4.0.0-rc.6
+        version: 4.0.0-rc.6(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.4)
+
   packages/ui/stdio-agent:
     devDependencies:
       '@cordisjs/plugin-include':
@@ -1762,6 +1810,9 @@ importers:
       '@deepseek-ai/dsh-sandbox':
         specifier: workspace:^
         version: link:../../packages/sandbox/sandbox
+      '@deepseek-ai/dsh-sandbox-policy':
+        specifier: workspace:^
+        version: link:../../packages/sandbox/sandbox-policy
       '@deepseek-ai/dsh-scope':
         specifier: workspace:^
         version: link:../../packages/core/scope

python/sdk-runtime/package.json

@@ -35,6 +35,7 @@
     "@deepseek-ai/dsh-permission": "workspace:^",
     "@deepseek-ai/dsh-repeat-tool-guard": "workspace:^",
     "@deepseek-ai/dsh-sandbox": "workspace:^",
+    "@deepseek-ai/dsh-sandbox-policy": "workspace:^",
     "@deepseek-ai/dsh-scope": "workspace:^",
     "@deepseek-ai/dsh-session": "workspace:^",
     "@deepseek-ai/dsh-session-persistence": "workspace:^",

scripts/doc-budgets.manifest.json

@@ -1,7 +1,7 @@
 {
   "AGENTS.md": 1802,
   "docs/AGENTS.md": 1315,
-  "docs/architecture.md": 1790,
+  "docs/architecture.md": 1800,
   "docs/cordis-primer.md": 550,
   "docs/defensive-patterns.md": 550,
   "docs/testing.md": 800,

scripts/gen-doc-graphs.ts

@@ -180,6 +180,15 @@ const SERVICE_ROLES: ServiceRole[] = [
     consumers: ['bash-sandbox'],
     note: 'Consumers hand over the exact argv they are about to spawn; same-world backends wrap it under a per-call policy and report enforcement.',
   },
+  {
+    key: 'sandboxPolicy',
+    pkg: 'sandbox',
+    title: 'Sandbox policy home',
+    mode: 'core',
+    implementations: [],
+    consumers: ['bash-sandbox', 'fs-sandbox', 'tool-bash', 'tool-fs'],
+    note: 'The one home for the deployment default mode + workspace root and the per-session `sandbox/mode` override; both enforcing families read it so bash and fs cannot confine to different roots.',
+  },
   {
     key: 'approval',
     pkg: 'approval',
@@ -212,10 +221,10 @@ const SERVICE_ROLES: ServiceRole[] = [
     pkg: 'fs',
     title: 'Filesystem provider seam',
     mode: 'seam',
-    implementations: ['fs-local'],
+    implementations: ['fs-local', 'fs-sandbox'],
     consumers: ['tool-fs'],
     companions: ['fs-policy'],
-    note: 'tool-fs executes read/write/edit through ctx.fs; fs-policy contributes observed-state checks through the fs/* event gate.',
+    note: 'tool-fs executes read/write/edit through ctx.fs; fs-sandbox fences mutations by the shared sandbox mode; fs-policy contributes observed-state checks through the fs/* event gate.',
   },
   {
     key: 'compact',

tsconfig.build.json

@@ -41,11 +41,13 @@
     { "path": "./packages/bash/bash-local" },
     { "path": "./packages/sandbox/sandbox" },
     { "path": "./packages/sandbox/sandbox-local" },
+    { "path": "./packages/sandbox/sandbox-policy" },
     { "path": "./packages/bash/bash-sandbox" },
     { "path": "./packages/bash/tool-bash" },
     { "path": "./packages/fs/fs" },
     { "path": "./packages/fs/fs-local" },
     { "path": "./packages/fs/fs-policy" },
+    { "path": "./packages/fs/fs-sandbox" },
     { "path": "./packages/fs/tool-fs" },
     { "path": "./packages/web/web" },
     { "path": "./packages/web/web-search-exa" },

tsconfig.json

@@ -50,11 +50,13 @@
     { "path": "./packages/bash/bash-local" },
     { "path": "./packages/sandbox/sandbox" },
     { "path": "./packages/sandbox/sandbox-local" },
+    { "path": "./packages/sandbox/sandbox-policy" },
     { "path": "./packages/bash/bash-sandbox" },
     { "path": "./packages/bash/tool-bash" },
     { "path": "./packages/fs/fs" },
     { "path": "./packages/fs/fs-local" },
     { "path": "./packages/fs/fs-policy" },
+    { "path": "./packages/fs/fs-sandbox" },
     { "path": "./packages/fs/tool-fs" },
     { "path": "./packages/compact/compact" },
     { "path": "./packages/compact/compact-basic" },