Optimize workspace instruction change detection

docs/rfc/implemented/architecture/2026-06-17-filesystem-capability-seam.md

@@ -81,7 +81,7 @@ Resolved targets must expose at least three concepts:
 - An opaque `targetKey`, used for stale guards and file-state lookup. The local backend might use a realpath-like key; a remote backend might use a workspace URI or file id. Consumers must not parse or assume this is a local absolute path.
 - A `displayPath`, used for model/UI-facing output. It may be a local absolute path, workspace-relative path, or remote URI depending on the backend.
 
-Read and mutation results must include an opaque file `version`. A local backend can use mtime/size or a hash-like token; a remote backend can use a revision id. The `dsh-fs-policy` plugin records versions for stale checks; consumers may display related metadata but must not interpret the version token.
+Read and mutation results must include an opaque file `version`. The local backend derives its token from bigint stat metadata (`dev`, `ino`, `size`, `mtimeNs`, and `ctimeNs`) so same-size rewrites and inode replacement invalidate consumers reliably; a remote backend can use a revision id or hash-like token. The `dsh-fs-policy` plugin records versions for stale checks; consumers may display related metadata but must not interpret the version token.
 
 The provider hands back decoded text: `readText` returns a whole regular text file, `streamText` streams the same text semantics for large files. Both own regular-file checks, bounded line/output handling is NOT theirs — line windowing, numbered-line rendering, and total-line accounting live in the executor (`dsh-tool-fs`), which reads through `ctx.fs` and renders the model-facing window. The provider owns UTF-8 decoding and binary/NUL rejection; it does not know about line windows or views.
 

docs/rfc/implemented/feature/2026-06-24-workspace-context.md

@@ -60,7 +60,7 @@ There is intentionally no watcher. Detection occurs at the next successful struc
 
 `maxBytes` is required and applies separately to a rendered baseline or one dynamic reconciliation batch; there is no implicit or unbounded render budget. Non-positive and non-finite values disable loading. When content exceeds the budget, broader files are omitted before the most-specific file is truncated. A visible `Workspace instruction budget ...` notice names omitted and truncated paths and byte counts, and output never exceeds the configured bytes.
 
-`maxSourceBytes` is a positive per-file cap with a 1 MiB default. The loader checks reported size before reading and still consumes content through `streamText()` with a running UTF-8 byte count, so missing/stale metadata cannot force an unbounded allocation. An oversized winning candidate is unavailable rather than a reason to fall through to another same-directory name. The plugin deliberately keeps no process-wide content cache: every reconciliation observes the current bounded text, then computes the SHA-1 used by visible structured duplicate-suppression state.
+`maxSourceBytes` is a positive per-file cap with a 1 MiB default. The loader checks reported size before reading and still consumes content through `streamText()` with a running UTF-8 byte count, so missing/stale metadata cannot force an unbounded allocation. An oversized winning candidate is unavailable rather than a reason to fall through to another same-directory name. The plugin deliberately keeps no process-wide cache and never retains instruction prose. It keeps only `{ path, version, digest }` per effective scope in a `WeakMap<Session, Map<scope, state>>`: a matching provider `FsVersion` plus matching effective prompt state skips the read, while a changed version triggers a bounded read and SHA-1 confirmation. SHA-1 remains the cross-provider content identity persisted in visible structured metadata; provider versions are only an in-memory invalidation fast path. Cache transitions for model-visible changes commit only when the corresponding context survives the complete tool-result policy chain.
 
 ## Alternatives considered
 

packages/fs/fs-local/README.md

@@ -13,7 +13,7 @@ await ctx.plugin(LocalFileSystem, { cwd: process.cwd() })
 ## Behavior
 
 - **`resolve(path, opts?)`** — a relative `path` resolves against `opts.cwd` when the caller supplies one (the model-facing tools pass the calling agent's session cwd — see [the per-session cwd RFC](../../../docs/rfc/implemented/architecture/2026-07-02-fs-per-session-cwd.md)), else `config.cwd` (default `process.cwd()`); an absolute `path` ignores both. `opts.signal` is checked before and after local resolution, while a remote sibling backend may use it to abort its round-trip. The `targetKey` is the file's `realpath`, so two input paths reaching the same file through symlinks share one identity, and writes/edits land on the link target (preserving the link). A not-yet-existing path uses the realpathed parent directory plus basename when the parent exists; only an unresolvable parent falls back to the absolute path. `displayPath` is the absolute (un-resolved) path.
-- **`stat`** — returns `FsInfo` (`version` = `mtimeMs:size`, `type` of `file`/`directory`/`other`, byte `size`) or `undefined` when the target is absent.
+- **`stat`** — returns `FsInfo` (`version` = an opaque token derived from bigint `dev:ino:size:mtimeNs:ctimeNs`, `type` of `file`/`directory`/`other`, byte `size`) or `undefined` when the target is absent.
 - **`readText` / `streamText`** — UTF-8 only. `readText` reads the whole file; `streamText` streams it in chunks (cross-chunk decoding) so a huge file never has to be held whole in memory. Both reject invalid UTF-8 and NUL-byte binary samples (`FS_NOT_TEXT`) and non-regular targets. The `read` tool (`@deepseek-ai/dsh-tool-fs`) decides which to call by size and owns the line windowing.
 - **`listDir`** — lists one directory level in stable `name.localeCompare()` order. Each entry carries the child basename, type, resolved child target (`displayPath` under the listed directory, `targetKey` as the realpath identity), and cheap stat metadata (`version`, plus `size` for regular files). It never opens or decodes file contents. Missing targets report `FS_NOT_FOUND`, file/special-file targets report `FS_NOT_DIRECTORY`, aborted calls report `FS_ABORTED`, permission failures report `FS_PERMISSION_DENIED`, and other listing or child metadata I/O failures report `FS_IO_ERROR`. Broken/disappeared children are returned as `other` without metadata, but permission/IO failures while resolving a child fail the whole listing with a structured `FsError`.
 - **`writeText`** — atomic: writes to a temp file opened exclusively (`wx`, `0o600`) inside a randomly-named private staging dir (`0o700`) next to the target, fsyncs, then renames over the target. An existing file's mode is preserved, while new files default to `0o600`. The `expected` guard is OPTIONAL: omitting it unconditionally creates-or-overwrites; `createIfAbsent` creates a missing target and rejects an existing one (`FS_NOT_OBSERVED`); `replaceIfVersion` replaces only at the observed version (a missing target or mismatch is `FS_STALE_VERSION`).

packages/fs/fs-local/src/fsio.ts

@@ -21,7 +21,7 @@
 import { randomUUID } from 'node:crypto'
 import { createReadStream } from 'node:fs'
 import { chmod, lstat, mkdir, open, readFile, realpath, readdir, rename, rm, stat } from 'node:fs/promises'
-import type { Dirent, Stats } from 'node:fs'
+import type { BigIntStats, Dirent, Stats } from 'node:fs'
 import { basename, dirname, join, resolve } from 'node:path'
 import { TextDecoder } from 'node:util'
 import { FsError, FsTargetKey, FsVersion } from '@deepseek-ai/dsh-fs'
@@ -76,9 +76,9 @@ async function readFileAbortable(absolutePath: string, verb: 'read' | 'edit', si
   }
 }
 
-/** Opaque version token from a stat: millisecond mtime plus byte size. */
-function versionOf(info: Stats): FsVersion {
-  return FsVersion(`${info.mtimeMs}:${info.size}`)
+/** Opaque version token from high-resolution identity and freshness metadata. */
+function versionOf(info: BigIntStats): FsVersion {
+  return FsVersion(`${info.dev}:${info.ino}:${info.size}:${info.mtimeNs}:${info.ctimeNs}`)
 }
 
 /**
@@ -176,18 +176,21 @@ export async function resolveLocalTarget(cwd: string, path: string): Promise<Loc
   }
 }
 
-function pathType(info: Stats): PathInfo['type'] {
+function pathType(info: Stats | BigIntStats): PathInfo['type'] {
   if (info.isFile()) return 'file'
   if (info.isDirectory()) return 'directory'
   return 'other'
 }
 
-function pathLinkType(info: Stats): PathLinkInfo['type'] {
+function pathLinkType(info: Stats | BigIntStats): PathLinkInfo['type'] {
   if (info.isSymbolicLink()) return 'symlink'
   return pathType(info)
 }
 
-async function probeStats(absolutePath: string, readStats: (path: string) => Promise<Stats>): Promise<Stats | null> {
+async function probeStats<T extends Stats | BigIntStats>(
+  absolutePath: string,
+  readStats: (path: string) => Promise<T>,
+): Promise<T | null> {
   try {
     return await readStats(absolutePath)
   } catch (error: unknown) {
@@ -206,9 +209,14 @@ async function probeStats(absolutePath: string, readStats: (path: string) => Pro
  * @returns the metadata, or null when the path — or a parent segment — does not exist.
  */
 export async function probe(absolutePath: string): Promise<PathInfo | null> {
-  const info = await probeStats(absolutePath, stat)
+  const info = await probeStats(absolutePath, path => stat(path, { bigint: true }))
   if (!info) return null
-  return { version: versionOf(info), mode: info.mode & 0o777, type: pathType(info), size: info.size }
+  return {
+    version: versionOf(info),
+    mode: Number(info.mode & 0o777n),
+    type: pathType(info),
+    size: Number(info.size),
+  }
 }
 
 /**
@@ -217,9 +225,14 @@ export async function probe(absolutePath: string): Promise<PathInfo | null> {
  * @returns path-entry metadata, or null when the entry is absent.
  */
 export async function probeNoFollow(absolutePath: string): Promise<PathLinkInfo | null> {
-  const info = await probeStats(absolutePath, lstat)
+  const info = await probeStats(absolutePath, path => lstat(path, { bigint: true }))
   if (!info) return null
-  return { version: versionOf(info), mode: info.mode & 0o777, type: pathLinkType(info), size: info.size }
+  return {
+    version: versionOf(info),
+    mode: Number(info.mode & 0o777n),
+    type: pathLinkType(info),
+    size: Number(info.size),
+  }
 }
 
 // --- Directory listing ---

packages/fs/fs-local/tests/filesystem.spec.ts

@@ -7,7 +7,7 @@
  */
 
 import { afterEach, beforeEach, describe, expect, it } from 'vitest'
-import { mkdir, mkdtemp, readFile, realpath, rm, stat, symlink, writeFile, unlink } from 'node:fs/promises'
+import { mkdir, mkdtemp, readFile, realpath, rm, stat, symlink, unlink, utimes, writeFile } from 'node:fs/promises'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { Context } from 'cordis'
@@ -99,6 +99,20 @@ describe('stat', () => {
     expect(await fs.stat(await fs.resolve('missing.txt'))).toBeUndefined()
   })
 
+  it('changes version after a same-size rewrite even when mtime is restored', async () => {
+    const path = join(dir, 'same-size.txt')
+    await writeFile(path, 'first')
+    const target = await fs.resolve(path)
+    const beforeInfo = await stat(path)
+    const beforeVersion = await versionOf(target)
+
+    await fs.writeText(target, 'other')
+    await utimes(path, beforeInfo.atime, beforeInfo.mtime)
+
+    expect((await stat(path)).size).toBe(beforeInfo.size)
+    expect(await versionOf(target)).not.toBe(beforeVersion)
+  })
+
   it('honors a pre-aborted signal', async () => {
     await expect(fs.stat(await fs.resolve('a.txt'), AbortSignal.abort())).rejects.toMatchObject({ code: 'FS_ABORTED' })
   })
@@ -327,9 +341,6 @@ describe('writeText', () => {
     await writeFile(join(dir, 'a.txt'), 'v1')
     const target = await fs.resolve('a.txt')
     const before = await versionOf(target)
-    // Change the byte length so the mtimeMs:size token provably differs (a
-    // same-size same-tick rewrite can collide — the documented version-token
-    // limitation; not what this test is about).
     const outcome = await fs.writeText(target, 'a much longer replacement body', { kind: 'replaceIfVersion', version: before })
     expect(outcome.version).not.toBe(before)
     expect(outcome.version).toBe(await versionOf(target))

packages/fs/fs/src/types.ts

@@ -41,16 +41,17 @@ export function FsTargetKey(key: string): FsTargetKey {
 
 /**
  * Opaque file-version token — the freshness token a write/edit guards against.
- * The local backend derives it from mtime+size; a remote backend might use a
- * revision id. The policy layer records it for stale checks; consumers may
- * display related metadata but MUST NOT interpret this token.
+ * The local backend derives it from high-resolution stat identity and freshness
+ * fields; a remote backend might use a revision id. The policy layer records it
+ * for stale checks; consumers may display related metadata but MUST NOT
+ * interpret this token.
  */
 export type FsVersion = Branded<'FsVersion'>
 
 /**
  * Brand a string as an {@link FsVersion}. For backend use only — a consumer
  * never manufactures a version, it receives one from `stat`/write/edit outcomes.
- * @param v - the backend's raw version string (the local backend derives it from mtime+size).
+ * @param v - the backend's raw version string.
  * @returns the same string, branded; no validation is performed.
  */
 export function FsVersion(v: string): FsVersion {

packages/prompt/workspace-context/README.md

@@ -48,7 +48,7 @@ The core `context/message` envelope is disabled for these messages because the p
 
 Model-visible text contains no hidden state markers. Each dynamic context event instead carries JSON metadata with a versioned list of `{ action, scope, path, previousPath?, digest? }` changes. On every relevant tool touch, the plugin reconstructs loaded state from its visible session events and overlays a short in-memory pending window for context present on the immutable top-level `tools/result` but not yet appended by the loop. Nested Code Mode results stage pending changes under the outer execution token for same-run duplicate suppression; the outer result rolls that state back and recommits only contexts that survived outer policy.
 
-An unchanged path and SHA-1 content digest is not injected again. Resume works because visible metadata is persisted in the session log. Compaction re-arms a scope after its context event leaves the visible surface. A removal is a tombstone, so a later candidate reappearance is loaded again. Only changes actually rendered within the byte budget enter metadata and pending state; an omitted change remains eligible for a later touch.
+An unchanged path and SHA-1 content digest is not injected again. A per-session, per-scope metadata cache stores only `{ path, version, digest }`: when the provider's opaque `FsVersion` and the effective visible state both match, reconciliation skips the content read; a changed version triggers a bounded read and SHA-1 confirmation before any model-visible update. Resume works because SHA-1 state is persisted in the session log, while an empty in-memory version cache merely causes one confirming read. Compaction re-arms a scope after its context event leaves the visible surface even when the cached version is unchanged. A removal is a tombstone, so a later candidate reappearance is loaded again. Only model-visible changes actually rendered within the byte budget enter metadata, pending state, and the version cache; an omitted change remains eligible for a later touch, while a same-digest version refresh updates metadata only.
 
 The frozen baseline itself is not rewritten mid-instance. Its initial path/digest map is retained as comparison state; the next successful filesystem touch appends any baseline replacement or removal. A resumed loop recomposes the current baseline and also reconciles still-visible dynamic scopes during prefix composition. There is no file watcher, so an on-disk change becomes visible at the next successful `read`, `write`, or `edit` touch, or when a resumed loop composes its prefix.
 
@@ -72,7 +72,7 @@ The user-global file is always `$DSH_HOME/AGENTS.md`; the candidate list only co
 
 Rendering preserves the most specific instruction files first. It drops whole broader files before truncating the most-specific file and emits a visible `Workspace instruction budget ...` notice naming omitted and truncated paths. The rendered bytes never exceed `maxBytes`.
 
-Instruction content is read through `streamText()` under `maxSourceBytes`, even when provider metadata omits size or a file grows after its metadata probe. An oversized file is ignored without falling through to a lower-priority same-directory candidate; during dynamic reconciliation it is temporarily unavailable rather than removed. The plugin keeps no process-wide prose cache: every reconciliation observes current content, computes its SHA-1 only after the bounded read, and relies on persisted structured metadata for duplicate suppression.
+Instruction content is read through `streamText()` under `maxSourceBytes`, even when provider metadata omits size or a file grows after its metadata probe. An oversized file is ignored without falling through to a lower-priority same-directory candidate; during dynamic reconciliation it is temporarily unavailable rather than removed. The plugin keeps no process-wide cache and never caches instruction prose. Its session-local scope cache uses provider versions only as a fast invalidation signal; after invalidation, SHA-1 over the bounded read remains the cross-provider content identity stored in structured session metadata.
 
 ## Non-goals
 

packages/prompt/workspace-context/src/files.ts

@@ -7,7 +7,7 @@
 import { createReadStream } from 'node:fs'
 import { lstat, stat } from 'node:fs/promises'
 import { dirname, isAbsolute, join, relative, resolve } from 'node:path'
-import type { FileSystem, FsInfo, FsPathInfo, FsTarget } from '@deepseek-ai/dsh-fs'
+import type { FileSystem, FsInfo, FsPathInfo, FsTarget, FsVersion } from '@deepseek-ai/dsh-fs'
 import { DEFAULT_DSH_HOME_DISPLAY, defaultDshHome } from '@deepseek-ai/dsh-paths'
 import { resolveConfig, resolveDiscoveryConfig, type ResolvedConfig } from './config.ts'
 import { renderWorkspaceContext, type RenderedWorkspaceContext } from './render.ts'
@@ -21,11 +21,21 @@ export interface InstructionFile {
 /** An instruction file whose UTF-8 content was read successfully. */
 export interface LoadedInstructionFile extends InstructionFile {
   content: string
+  /** Provider freshness token when the file was loaded through `ctx.fs`. */
+  version?: FsVersion
 }
 
 interface DiscoveredInstructionFile extends InstructionFile {
   target?: FsTarget
   size?: number
+  version?: FsVersion
+}
+
+/** Provider metadata for a winning scope candidate before its content is read. */
+export interface ProbedInstructionFile extends InstructionFile {
+  target: FsTarget
+  version: FsVersion
+  size?: number
 }
 
 interface DiscoverOptions {
@@ -49,7 +59,7 @@ export interface RenderedInstructionSet {
 
 /** Tri-state scope probe that distinguishes confirmed absence from provider failure. */
 export type ScopeInstructionProbe =
-  | { kind: 'present'; file: LoadedInstructionFile }
+  | { kind: 'present'; file: ProbedInstructionFile }
   | { kind: 'absent' }
   | { kind: 'unavailable' }
 
@@ -75,14 +85,14 @@ async function fsStatFile(
   path: string,
   fileSystem: FileSystem,
   signal?: AbortSignal,
-): Promise<{ target: FsTarget; size?: number } | undefined> {
+): Promise<{ target: FsTarget; size?: number; version: FsVersion } | undefined> {
   try {
     const pathInfo = await fileSystem.lstat(path, undefined, signal)
     if (pathInfo?.type !== 'file') return undefined
     const target = await fileSystem.resolve(path, signalOptions(signal))
     const info = await fileSystem.stat(target, signal)
     if (info?.type !== 'file') return undefined
-    return { target, ...info.size === undefined ? {} : { size: info.size } }
+    return { target, version: info.version, ...info.size === undefined ? {} : { size: info.size } }
   } catch {
     signal?.throwIfAborted()
     // Provider absence and discovery races are both non-fatal.
@@ -94,7 +104,7 @@ async function statFile(
   path: string,
   fileSystem?: FileSystem,
   signal?: AbortSignal,
-): Promise<{ target?: FsTarget; size?: number } | undefined> {
+): Promise<{ target?: FsTarget; size?: number; version?: FsVersion } | undefined> {
   return fileSystem === undefined ? nodeStatFile(path, signal) : fsStatFile(path, fileSystem, signal)
 }
 
@@ -316,7 +326,14 @@ export async function loadBaselineInstructionSet(
   const loaded: LoadedInstructionFile[] = []
   for (const file of discovered) {
     const content = await readBounded(file, config.maxSourceBytes, fileSystem, options.signal)
-    if (content !== undefined) loaded.push({ absolutePath: file.absolutePath, displayPath: file.displayPath, content })
+    if (content !== undefined) {
+      loaded.push({
+        absolutePath: file.absolutePath,
+        displayPath: file.displayPath,
+        content,
+        ...file.version === undefined ? {} : { version: file.version },
+      })
+    }
   }
   if (loaded.length === 0) return undefined
   const rendered = renderWorkspaceContext(loaded, { maxBytes: config.maxBytes })
@@ -329,11 +346,11 @@ export async function loadBaselineInstructionSet(
  * @param scope - `user-global`, `.`, or a project-relative directory.
  * @param projectRoot - project root used to resolve and display project scopes.
  * @param resolved - normalized plugin configuration.
- * @param fileSystem - provider used for no-follow probing and reading.
- * @param signal - cancellation for provider probes and streaming.
- * @returns present content, confirmed absence, or temporary unavailability.
+ * @param fileSystem - provider used for no-follow probing.
+ * @param signal - cancellation for provider probes.
+ * @returns present metadata, confirmed absence, or temporary unavailability.
  */
-export async function loadScopeInstruction(
+export async function probeScopeInstruction(
   scope: string,
   projectRoot: string,
   resolved: ResolvedConfig,
@@ -364,19 +381,42 @@ export async function loadScopeInstruction(
       return { kind: 'unavailable' }
     }
     if (info?.type !== 'file') return { kind: 'unavailable' }
-    const discovered: DiscoveredInstructionFile = {
+    const file: ProbedInstructionFile = {
       absolutePath,
       displayPath: scope === 'user-global' ? userGlobalDisplayPath(resolved.dshHome) : relativeDisplay(projectRoot, absolutePath),
       target,
+      version: info.version,
       ...info.size === undefined ? {} : { size: info.size },
     }
-    const content = await readBounded(discovered, resolved.maxSourceBytes, fileSystem, signal)
-    if (content === undefined) return { kind: 'unavailable' }
-    return { kind: 'present', file: { absolutePath, displayPath: discovered.displayPath, content } }
+    return { kind: 'present', file }
   }
   return { kind: 'absent' }
 }
 
+/**
+ * Read one already-probed scope candidate under the configured source cap.
+ * @param file - winning provider candidate and its metadata snapshot.
+ * @param maxSourceBytes - maximum UTF-8 bytes accepted from the source.
+ * @param fileSystem - provider used for the streaming read.
+ * @param signal - cancellation for provider streaming.
+ * @returns loaded content with the probed version, or undefined when unavailable.
+ */
+export async function readScopeInstruction(
+  file: ProbedInstructionFile,
+  maxSourceBytes: number,
+  fileSystem: FileSystem,
+  signal?: AbortSignal,
+): Promise<LoadedInstructionFile | undefined> {
+  const content = await readBounded(file, maxSourceBytes, fileSystem, signal)
+  if (content === undefined) return undefined
+  return {
+    absolutePath: file.absolutePath,
+    displayPath: file.displayPath,
+    content,
+    version: file.version,
+  }
+}
+
 function userGlobalDisplayPath(dshHome: string): string {
   return dshHome === resolve(defaultDshHome()) ? `${DEFAULT_DSH_HOME_DISPLAY}/AGENTS.md` : '$DSH_HOME/AGENTS.md'
 }

packages/prompt/workspace-context/src/index.ts

@@ -16,13 +16,17 @@ import type { PostToolDecision, ToolExecution, ToolExecutionResult, ToolExecutio
 import { Config, resolveConfig, type ResolvedConfig } from './config.ts'
 import { loadBaselineInstructionSet } from './files.ts'
 import {
-  baselineInstructionChanges,
+  applyInstructionVersionUpdates,
+  baselineInstructionState,
   commitPendingInstructionContexts,
   dynamicInstructionContext,
   name,
   reconcileInstructionContext,
+  retainedInstructionVersionUpdates,
   rollbackPendingInstructionChanges,
   workspaceContextMessage,
+  type InstructionVersionCache,
+  type InstructionVersionUpdate,
   type PendingInstructionChange,
 } from './state.ts'
 import type { WorkspaceInstructionChange } from './render.ts'
@@ -43,7 +47,13 @@ export function apply(ctx: Context, config: Config): void {
   const resolved: ResolvedConfig = resolveConfig(config)
   const pendingNestedChanges = new WeakMap<object, Map<string, PendingInstructionChange>>()
   const baselineInstructionStates = new WeakMap<object, Map<string, WorkspaceInstructionChange>>()
-  const pendingByParent = new Map<ToolExecutionToken, { agent: Agent; changes: WorkspaceInstructionChange[] }>()
+  const instructionVersions: InstructionVersionCache = new WeakMap()
+  const pendingVersionUpdates = new Map<ToolExecutionToken, InstructionVersionUpdate[]>()
+  const pendingByParent = new Map<ToolExecutionToken, {
+    agent: Agent
+    changes: WorkspaceInstructionChange[]
+    versionUpdates: InstructionVersionUpdate[]
+  }>()
 
   ctx.on('agent/session-prefix', async (agent: Agent, _prefix, signal, next): Promise<Message[]> => {
     const rest = await next()
@@ -61,22 +71,26 @@ export function apply(ctx: Context, config: Config): void {
       instructionFileCandidates: resolved.instructionFileCandidates,
       signal,
     }, fileSystem)
-    baselineInstructionStates.set(agent.session, baselineInstructionChanges(instructions?.included ?? []))
+    const baseline = baselineInstructionState(instructions?.included ?? [])
+    baselineInstructionStates.set(agent.session, baseline.changes)
+    instructionVersions.set(agent.session, baseline.versions)
 
     const update = await reconcileInstructionContext(
       agent,
       resolved,
       pendingNestedChanges,
       baselineInstructionStates,
+      instructionVersions,
       fileSystem,
       { includeBaselineScopes: false, signal },
     )
     if (update !== undefined) {
-      agent.inject(update.content, {
-        source: update.source,
-        envelope: update.envelope,
-        meta: update.meta,
+      agent.inject(update.context.content, {
+        source: update.context.source,
+        envelope: update.context.envelope,
+        meta: update.context.meta,
       })
+      applyInstructionVersionUpdates(agent.session, update.versionUpdates, instructionVersions)
     }
     if (instructions === undefined || instructions.rendered.text.length === 0) return rest
     return [workspaceContextMessage(instructions.rendered.text), ...rest]
@@ -97,33 +111,41 @@ export function apply(ctx: Context, config: Config): void {
     if (downstream.kind === 'block') return downstream
     const fileSystem = ctx.get('fs')
     if (fileSystem === undefined) return downstream
-    const context = await dynamicInstructionContext(
+    const update = await dynamicInstructionContext(
       exec.agent,
       exec,
       result,
       resolved,
       pendingNestedChanges,
       baselineInstructionStates,
+      instructionVersions,
       fileSystem,
     )
-    if (context === undefined) return downstream
+    if (update === undefined) return downstream
+    pendingVersionUpdates.set(exec.token, update.versionUpdates)
     return {
       kind: 'accept',
       ...downstream.content !== undefined ? { content: downstream.content } : {},
-      additionalContexts: [context, ...downstream.additionalContexts ?? []],
+      additionalContexts: [update.context, ...downstream.additionalContexts ?? []],
     }
   })
 
   ctx.on('tools/result', (exec: ToolExecution, result: ToolExecutionResult) => {
+    const ownVersionUpdates = pendingVersionUpdates.get(exec.token) ?? []
+    pendingVersionUpdates.delete(exec.token)
     if (exec.parent !== undefined) {
       if (exec.agent === undefined) return
       // Child contexts participate in duplicate suppression within one composite
       // run, but remain provisional until the parent reaches its final policy.
       const changes = commitPendingInstructionContexts(exec.agent, result.additionalContexts, pendingNestedChanges)
       if (changes.length === 0) return
+      const versionUpdates = retainedInstructionVersionUpdates(ownVersionUpdates, changes)
       const staged = pendingByParent.get(exec.parent)
-      if (staged === undefined) pendingByParent.set(exec.parent, { agent: exec.agent, changes })
-      else staged.changes.push(...changes)
+      if (staged === undefined) pendingByParent.set(exec.parent, { agent: exec.agent, changes, versionUpdates })
+      else {
+        staged.changes.push(...changes)
+        staged.versionUpdates.push(...versionUpdates)
+      }
       return
     }
 
@@ -135,6 +157,12 @@ export function apply(ctx: Context, config: Config): void {
       rollbackPendingInstructionChanges(staged.agent, staged.changes, pendingNestedChanges)
     }
     if (exec.agent === undefined) return
-    commitPendingInstructionContexts(exec.agent, result.additionalContexts, pendingNestedChanges)
+    const committed = commitPendingInstructionContexts(exec.agent, result.additionalContexts, pendingNestedChanges)
+    const stagedVersionUpdates = staged?.versionUpdates ?? []
+    const versionUpdates = retainedInstructionVersionUpdates(
+      [...stagedVersionUpdates, ...ownVersionUpdates],
+      committed,
+    )
+    applyInstructionVersionUpdates(exec.agent.session, versionUpdates, instructionVersions)
   })
 }

packages/prompt/workspace-context/src/state.ts

@@ -6,8 +6,8 @@
 
 import type { Agent, HookContext } from '@deepseek-ai/dsh-agent'
 import type { Message } from '@deepseek-ai/dsh-llm'
-import type { JsonValue } from '@deepseek-ai/dsh-session'
-import type { FileSystem } from '@deepseek-ai/dsh-fs'
+import type { JsonValue, Session } from '@deepseek-ai/dsh-session'
+import type { FileSystem, FsVersion } from '@deepseek-ai/dsh-fs'
 import type { ToolExecution, ToolExecutionResult } from '@deepseek-ai/dsh-tools'
 import type { ResolvedConfig } from './config.ts'
 import { instructionContentSha1 } from './digest.ts'
@@ -15,7 +15,8 @@ import {
   ancestorChain,
   descendantDirsBetween,
   findProjectRoot,
-  loadScopeInstruction,
+  probeScopeInstruction,
+  readScopeInstruction,
   relativeDisplay,
   type LoadedInstructionFile,
 } from './files.ts'
@@ -37,6 +38,28 @@ export interface PendingInstructionChange {
   afterSeq: number
 }
 
+/** Per-scope metadata cache; instruction prose is deliberately not retained. */
+export interface InstructionVersionState {
+  path: string
+  version: FsVersion
+  digest: string
+}
+
+/** Session-isolated fast-path state keyed by logical instruction scope. */
+export type InstructionVersionCache = WeakMap<Session, Map<string, InstructionVersionState>>
+
+/** A cache transition coupled to the model-visible change that authorizes it. */
+export interface InstructionVersionUpdate {
+  change: WorkspaceInstructionChange
+  state?: InstructionVersionState
+}
+
+/** Rendered reconciliation plus cache transitions awaiting final policy. */
+export interface ReconciledInstructionContext {
+  context: WorkspaceHookContext
+  versionUpdates: InstructionVersionUpdate[]
+}
+
 /** Plugin-owned raw context with required replay metadata. */
 export interface WorkspaceHookContext extends HookContext {
   envelope: 'raw'
@@ -103,7 +126,11 @@ function workspaceInstructionChanges(meta: JsonValue | undefined): WorkspaceInst
 }
 
 function sameInstructionChange(a: WorkspaceInstructionChange, b: WorkspaceInstructionChange): boolean {
-  return a.action === b.action && a.scope === b.scope && a.path === b.path && a.digest === b.digest
+  return a.action === b.action
+    && a.scope === b.scope
+    && a.path === b.path
+    && a.previousPath === b.previousPath
+    && a.digest === b.digest
 }
 
 function visibleInstructionChanges(
@@ -128,20 +155,72 @@ function visibleInstructionChanges(
 }
 
 /**
- * Convert retained baseline files into scope/path/digest comparison state.
+ * Convert retained baseline files into comparison and metadata-cache state.
  * @param files - baseline files that survived rendering.
- * @returns latest baseline state keyed by logical scope.
+ * @returns latest baseline changes and provider versions keyed by logical scope.
  */
-export function baselineInstructionChanges(files: LoadedInstructionFile[]): Map<string, WorkspaceInstructionChange> {
-  return new Map(files.map((file) => {
+export function baselineInstructionState(files: LoadedInstructionFile[]): {
+  changes: Map<string, WorkspaceInstructionChange>
+  versions: Map<string, InstructionVersionState>
+} {
+  const changes = new Map<string, WorkspaceInstructionChange>()
+  const versions = new Map<string, InstructionVersionState>()
+  for (const file of files) {
+    const digest = instructionContentSha1(file.content)
     const change: WorkspaceInstructionChange = {
       action: 'set',
       scope: scopeForDisplayPath(file.displayPath),
       path: file.displayPath,
-      digest: instructionContentSha1(file.content),
+      digest,
     }
-    return [change.scope, change]
-  }))
+    changes.set(change.scope, change)
+    if (file.version !== undefined) {
+      versions.set(change.scope, { path: file.displayPath, version: file.version, digest })
+    }
+  }
+  return { changes, versions }
+}
+
+function versionStatesFor(session: Session, cache: InstructionVersionCache): Map<string, InstructionVersionState> {
+  let states = cache.get(session)
+  if (states === undefined) {
+    states = new Map()
+    cache.set(session, states)
+  }
+  return states
+}
+
+/**
+ * Keep only cache updates whose model-visible changes survived final policy.
+ * @param updates - proposed updates from one or more reconciliations.
+ * @param committedChanges - transitions retained on the authoritative result.
+ * @returns updates authorized by an exact retained transition.
+ */
+export function retainedInstructionVersionUpdates(
+  updates: readonly InstructionVersionUpdate[],
+  committedChanges: readonly WorkspaceInstructionChange[],
+): InstructionVersionUpdate[] {
+  return updates.filter(update => committedChanges.some(change => sameInstructionChange(update.change, change)))
+}
+
+/**
+ * Apply authorized metadata-cache transitions without retaining instruction prose.
+ * @param session - owning session.
+ * @param updates - ordered set/delete transitions.
+ * @param cache - session-isolated metadata cache.
+ */
+export function applyInstructionVersionUpdates(
+  session: Session,
+  updates: readonly InstructionVersionUpdate[],
+  cache: InstructionVersionCache,
+): void {
+  if (updates.length === 0) return
+  const states = versionStatesFor(session, cache)
+  for (const update of updates) {
+    if (update.state === undefined) states.delete(update.change.scope)
+    else states.set(update.change.scope, update.state)
+  }
+  if (states.size === 0) cache.delete(session)
 }
 
 function pendingChangesFor(
@@ -217,18 +296,20 @@ function relativeScope(projectRoot: string, dir: string): string {
  * @param resolved - normalized plugin configuration.
  * @param pendingBySession - short pending window before returned context is logged.
  * @param baselineBySession - frozen baseline comparison state per session.
+ * @param versionCache - per-session scope metadata used to skip unchanged reads.
  * @param fileSystem - provider used for current file probes.
  * @param options - touched path and whether baseline scopes should be checked.
- * @returns a structured context update, or undefined when state is unchanged/unavailable.
+ * @returns rendered context plus deferred cache updates, or undefined when unchanged/unavailable.
  */
 export async function reconcileInstructionContext(
   agent: Agent,
   resolved: ResolvedConfig,
   pendingBySession: WeakMap<object, Map<string, PendingInstructionChange>>,
   baselineBySession: WeakMap<object, Map<string, WorkspaceInstructionChange>>,
+  versionCache: InstructionVersionCache,
   fileSystem: FileSystem,
   options: { touchedPath?: string; includeBaselineScopes: boolean; signal?: AbortSignal },
-): Promise<WorkspaceHookContext | undefined> {
+): Promise<ReconciledInstructionContext | undefined> {
   const session = agent.session
   const pending = pendingChangesFor(session, pendingBySession)
   const visible = visibleInstructionChanges(agent, pending)
@@ -247,57 +328,74 @@ export async function reconcileInstructionContext(
     for (const dir of descendantDirsBetween(cwd, options.touchedPath)) scopes.add(relativeScope(projectRoot, dir))
   }
 
-  const current = new Map<string, LoadedInstructionFile>()
-  const unavailable = new Set<string>()
+  const versions = versionStatesFor(session, versionCache)
   const seenAbsolutePaths = new Set<string>()
-  for (const scope of scopes) {
-    const probe = await loadScopeInstruction(scope, projectRoot, resolved, fileSystem, options.signal)
-    if (probe.kind === 'unavailable') {
-      unavailable.add(scope)
-      continue
-    }
-    if (probe.kind === 'absent') continue
-    const { file } = probe
-    if (seenAbsolutePaths.has(file.absolutePath)) continue
-    seenAbsolutePaths.add(file.absolutePath)
-    current.set(scope, file)
-  }
-
   const items: ChangeRenderItem[] = []
+  const versionUpdates: InstructionVersionUpdate[] = []
   for (const scope of scopes) {
-    if (unavailable.has(scope)) continue
     const previous = effective.get(scope)
-    const file = current.get(scope)
-    if (file === undefined) {
-      if (previous !== undefined && previous.action !== 'remove') {
-        items.push({
-          change: { action: 'remove', scope, path: previous.path },
-          file: { absolutePath: `removed:${scope}`, displayPath: previous.path, content: '' },
-        })
+    const probe = await probeScopeInstruction(scope, projectRoot, resolved, fileSystem, options.signal)
+    if (probe.kind === 'unavailable') continue
+    if (probe.kind === 'absent') {
+      if (previous === undefined || previous.action === 'remove') {
+        versions.delete(scope)
+        continue
       }
+      const change: WorkspaceInstructionChange = { action: 'remove', scope, path: previous.path }
+      items.push({
+        change,
+        file: { absolutePath: `removed:${scope}`, displayPath: previous.path, content: '' },
+      })
+      versionUpdates.push({ change })
       continue
     }
+    const { file: probedFile } = probe
+    if (seenAbsolutePaths.has(probedFile.absolutePath)) continue
+    seenAbsolutePaths.add(probedFile.absolutePath)
+    const cached = versions.get(scope)
+    if (
+      cached !== undefined
+      && cached.path === probedFile.displayPath
+      && cached.version === probedFile.version
+      && previous !== undefined
+      && previous.action !== 'remove'
+      && previous.path === cached.path
+      && previous.digest === cached.digest
+    ) continue
+
+    const file = await readScopeInstruction(probedFile, resolved.maxSourceBytes, fileSystem, options.signal)
+    if (file === undefined) continue
     const currentDigest = instructionContentSha1(file.content)
-    if (previous !== undefined && previous.action !== 'remove' && previous.path === file.displayPath && previous.digest === currentDigest) continue
+    const nextVersion: InstructionVersionState = {
+      path: file.displayPath,
+      version: probedFile.version,
+      digest: currentDigest,
+    }
+    if (previous !== undefined && previous.action !== 'remove' && previous.path === file.displayPath && previous.digest === currentDigest) {
+      versions.set(scope, nextVersion)
+      continue
+    }
     const action = previous === undefined || previous.action === 'remove' ? 'set' : 'replace'
     const previousPath = action === 'replace' && previous !== undefined && previous.path !== file.displayPath
       ? previous.path
       : undefined
-    items.push({
-      change: {
-        action,
-        scope,
-        path: file.displayPath,
-        ...previousPath === undefined ? {} : { previousPath },
-        digest: currentDigest,
-      },
-      file,
-    })
+    const change: WorkspaceInstructionChange = {
+      action,
+      scope,
+      path: file.displayPath,
+      ...previousPath === undefined ? {} : { previousPath },
+      digest: currentDigest,
+    }
+    items.push({ change, file })
+    versionUpdates.push({ change, state: nextVersion })
   }
   if (items.length === 0) return undefined
   const rendered = renderInstructionChanges(items, resolved.maxBytes)
   if (rendered.text.length === 0 || rendered.changes.length === 0) return undefined
-  return workspaceContextHook(rendered.text, rendered.changes)
+  return {
+    context: workspaceContextHook(rendered.text, rendered.changes),
+    versionUpdates: retainedInstructionVersionUpdates(versionUpdates, rendered.changes),
+  }
 }
 
 /**
@@ -308,8 +406,9 @@ export async function reconcileInstructionContext(
  * @param resolved - normalized plugin configuration.
  * @param pendingNestedChanges - per-session pending transition maps.
  * @param baselineInstructionStates - retained baseline comparison state.
+ * @param versionCache - per-session scope metadata used to skip unchanged reads.
  * @param fileSystem - provider used for current file probes.
- * @returns a structured context update, or undefined for irrelevant/failed/unchanged calls.
+ * @returns rendered context plus deferred cache updates, or undefined for irrelevant/failed/unchanged calls.
  */
 export async function dynamicInstructionContext(
   agent: Agent | undefined,
@@ -318,13 +417,14 @@ export async function dynamicInstructionContext(
   resolved: ResolvedConfig,
   pendingNestedChanges: WeakMap<object, Map<string, PendingInstructionChange>>,
   baselineInstructionStates: WeakMap<object, Map<string, WorkspaceInstructionChange>>,
+  versionCache: InstructionVersionCache,
   fileSystem: FileSystem,
-): Promise<WorkspaceHookContext | undefined> {
+): Promise<ReconciledInstructionContext | undefined> {
   if (agent === undefined || result.isError) return undefined
   const touchedPath = filePathFromExecution(exec)
   if (touchedPath === undefined) return undefined
   return reconcileInstructionContext(
-    agent, resolved, pendingNestedChanges, baselineInstructionStates, fileSystem,
+    agent, resolved, pendingNestedChanges, baselineInstructionStates, versionCache, fileSystem,
     {
       touchedPath,
       includeBaselineScopes: baselineInstructionStates.has(agent.session),

packages/prompt/workspace-context/tests/workspace-context.spec.ts

@@ -31,6 +31,7 @@ import {
   renderWorkspaceContext,
 } from '@deepseek-ai/dsh-workspace-context'
 import {
+  baselineInstructionState,
   commitPendingInstructionContexts,
   rollbackPendingInstructionChanges,
   type PendingInstructionChange,
@@ -46,7 +47,7 @@ async function write(path: string, content: string): Promise<void> {
 }
 
 class RecordingFileSystem extends FileSystem {
-  entries = new Map<string, { type: FsInfo['type']; content?: string }>()
+  entries = new Map<string, { type: FsInfo['type']; content?: string; version?: FsVersion }>()
   lstatTypes = new Map<string, FsPathInfo['type']>()
   throwOnStat = new Set<string>()
   omitSizes = new Set<string>()
@@ -68,7 +69,7 @@ class RecordingFileSystem extends FileSystem {
     const entry = this.entries.get(target.targetKey)
     if (entry === undefined) return undefined
     const info: FsInfo = {
-      version: FsVersion(`v:${target.targetKey}`),
+      version: entry.version ?? FsVersion(`v:${target.targetKey}:${entry.type}:${entry.content ?? ''}`),
       type: entry.type,
     }
     if (entry.content !== undefined && !this.omitSizes.has(target.targetKey)) info.size = Buffer.byteLength(entry.content, 'utf8')
@@ -1062,7 +1063,7 @@ describe('workspace context request injection', () => {
 
       expect(derivedText(agent)).toContain('ctx.fs rule')
       expect(derivedText(agent)).not.toContain('node fs rule')
-      expect(fs.readTargets).toEqual([join(root, 'AGENTS.md'), join(root, 'AGENTS.md')])
+      expect(fs.readTargets).toEqual([join(root, 'AGENTS.md')])
     } finally {
       await rm(root, { recursive: true, force: true })
       await rm(home, { recursive: true, force: true })
@@ -1084,7 +1085,7 @@ describe('workspace context request injection', () => {
       await composeBaselinePrefix(ctx, agent)
 
       expect(derivedText(agent)).toContain('provider-only rule')
-      expect(fs.readTargets).toEqual([join(root, 'AGENTS.md'), join(root, 'AGENTS.md')])
+      expect(fs.readTargets).toEqual([join(root, 'AGENTS.md')])
     } finally {
       await ctx.fiber.dispose()
       await rm(dirname(root), { recursive: true, force: true })
@@ -1490,6 +1491,22 @@ describe('workspace context request injection', () => {
 })
 
 describe('dynamic nested workspace context injection', () => {
+  it('builds persisted digest state without inventing a provider version', () => {
+    const state = baselineInstructionState([{
+      absolutePath: '/repo/AGENTS.md',
+      displayPath: 'AGENTS.md',
+      content: 'root rule',
+    }])
+
+    const change = state.changes.get('.')
+    expect(change).toMatchObject({
+      action: 'set',
+      path: 'AGENTS.md',
+    })
+    expect(change?.digest).toMatch(/^[a-f0-9]{40}$/)
+    expect(state.versions).toEqual(new Map())
+  })
+
   it('propagates the tool execution signal into dynamic filesystem reconciliation', async () => {
     const root = join(await tempRepo(), 'virtual-repo')
     const home = join(await tempRepo(), 'virtual-home')
@@ -1647,6 +1664,113 @@ describe('dynamic nested workspace context injection', () => {
     }
   })
 
+  it('skips instruction content reads while provider version and effective state are unchanged', async () => {
+    const root = join(await tempRepo(), 'virtual-repo')
+    const home = join(await tempRepo(), 'virtual-home')
+    const ctx = new Context()
+    try {
+      await ctx.plugin(SystemPrompt)
+      await ctx.plugin(ToolRegistry)
+      await ctx.plugin(RecordingFileSystem)
+      const fs = ctx.fs as RecordingFileSystem
+      const instructionPath = join(root, 'pkg/AGENTS.md')
+      fs.entries.set(join(root, '.git'), { type: 'directory' })
+      fs.entries.set(instructionPath, { type: 'file', content: 'nested package rule' })
+      fs.entries.set(join(root, 'pkg/file.txt'), { type: 'file', content: 'hello' })
+      await ctx.plugin(ToolFs)
+      await ctx.plugin(workspaceContext, { dshHome: home, maxBytes: 65536 })
+      const agent = stubAgent(root)
+
+      const first = await ctx.tools.execute({
+        callId: CallId('read-before-version-fast-path'), name: 'read', arguments: { file_path: 'pkg/file.txt' }, agent,
+      })
+      appendAdditionalContexts(agent, first)
+      const second = await ctx.tools.execute({
+        callId: CallId('read-with-version-fast-path'), name: 'read', arguments: { file_path: 'pkg/file.txt' }, agent,
+      })
+
+      expect(first.additionalContexts).toBeDefined()
+      expect(second.additionalContexts).toBeUndefined()
+      expect(fs.readTargets.filter(path => path === instructionPath)).toHaveLength(1)
+    } finally {
+      await ctx.fiber.dispose()
+      await rm(dirname(root), { recursive: true, force: true })
+      await rm(dirname(home), { recursive: true, force: true })
+    }
+  })
+
+  it('re-reads a changed provider version, then refreshes metadata when SHA-1 is unchanged', async () => {
+    const root = join(await tempRepo(), 'virtual-repo')
+    const home = join(await tempRepo(), 'virtual-home')
+    const ctx = new Context()
+    try {
+      await ctx.plugin(SystemPrompt)
+      await ctx.plugin(ToolRegistry)
+      await ctx.plugin(RecordingFileSystem)
+      const fs = ctx.fs as RecordingFileSystem
+      const instructionPath = join(root, 'pkg/AGENTS.md')
+      fs.entries.set(join(root, '.git'), { type: 'directory' })
+      fs.entries.set(instructionPath, { type: 'file', content: 'same package rule', version: FsVersion('revision-1') })
+      fs.entries.set(join(root, 'pkg/file.txt'), { type: 'file', content: 'hello' })
+      await ctx.plugin(ToolFs)
+      await ctx.plugin(workspaceContext, { dshHome: home, maxBytes: 65536 })
+      const agent = stubAgent(root)
+
+      const first = await ctx.tools.execute({
+        callId: CallId('read-before-same-digest-version-change'), name: 'read', arguments: { file_path: 'pkg/file.txt' }, agent,
+      })
+      appendAdditionalContexts(agent, first)
+      fs.entries.set(instructionPath, { type: 'file', content: 'same package rule', version: FsVersion('revision-2') })
+      const afterVersionChange = await ctx.tools.execute({
+        callId: CallId('read-after-same-digest-version-change'), name: 'read', arguments: { file_path: 'pkg/file.txt' }, agent,
+      })
+      const afterRefresh = await ctx.tools.execute({
+        callId: CallId('read-after-version-cache-refresh'), name: 'read', arguments: { file_path: 'pkg/file.txt' }, agent,
+      })
+
+      expect(afterVersionChange.additionalContexts).toBeUndefined()
+      expect(afterRefresh.additionalContexts).toBeUndefined()
+      expect(fs.readTargets.filter(path => path === instructionPath)).toHaveLength(2)
+    } finally {
+      await ctx.fiber.dispose()
+      await rm(dirname(root), { recursive: true, force: true })
+      await rm(dirname(home), { recursive: true, force: true })
+    }
+  })
+
+  it('isolates instruction version caches between sessions that touch the same scope', async () => {
+    const root = join(await tempRepo(), 'virtual-repo')
+    const home = join(await tempRepo(), 'virtual-home')
+    const ctx = new Context()
+    try {
+      await ctx.plugin(SystemPrompt)
+      await ctx.plugin(ToolRegistry)
+      await ctx.plugin(RecordingFileSystem)
+      const fs = ctx.fs as RecordingFileSystem
+      const instructionPath = join(root, 'pkg/AGENTS.md')
+      fs.entries.set(join(root, '.git'), { type: 'directory' })
+      fs.entries.set(instructionPath, { type: 'file', content: 'shared path, separate sessions' })
+      fs.entries.set(join(root, 'pkg/file.txt'), { type: 'file', content: 'hello' })
+      await ctx.plugin(ToolFs)
+      await ctx.plugin(workspaceContext, { dshHome: home, maxBytes: 65536 })
+
+      const first = await ctx.tools.execute({
+        callId: CallId('read-from-first-session'), name: 'read', arguments: { file_path: 'pkg/file.txt' }, agent: stubAgent(root),
+      })
+      const second = await ctx.tools.execute({
+        callId: CallId('read-from-second-session'), name: 'read', arguments: { file_path: 'pkg/file.txt' }, agent: stubAgent(root),
+      })
+
+      expect(first.additionalContexts).toBeDefined()
+      expect(second.additionalContexts).toBeDefined()
+      expect(fs.readTargets.filter(path => path === instructionPath)).toHaveLength(2)
+    } finally {
+      await ctx.fiber.dispose()
+      await rm(dirname(root), { recursive: true, force: true })
+      await rm(dirname(home), { recursive: true, force: true })
+    }
+  })
+
   it('replaces previously loaded instructions when the same file content changes', async () => {
     const root = await tempRepo()
     const home = await tempRepo()