Sync remaining chars-per-token prose in overview READMEs

The convergence pass found four summary-level sites still describing
the estimator as fixed char/4: packages/README.md (twice), the compact
group and interface READMEs, and compact-basic's package.json
description. All now say chars-per-token with the charsPerToken
default, matching the authoritative package README/module doc/RFC.

packages/README.md

@@ -34,7 +34,7 @@ dsh-session       ← dsh-llm, dsh-brand
 dsh-system-prompt ← dsh-llm
 dsh-agent         ← dsh-llm, dsh-session, dsh-brand
 dsh-compact       ← dsh-session, dsh-llm                (abstract compaction seam; tool deferred)
-dsh-compact-basic ← dsh-compact, dsh-session, dsh-llm, dsh-agent  (char/4 + token-budget retention backend)
+dsh-compact-basic ← dsh-compact, dsh-session, dsh-llm, dsh-agent  (chars-per-token + token-budget retention backend)
 dsh-tools         ← dsh-llm, dsh-system-prompt, dsh-agent
 dsh-bash-local    ← dsh-bash                       (BashExecutor impl)
 dsh-tool-bash     ← dsh-bash, dsh-tools            (bash tool schemas)
@@ -89,7 +89,7 @@ The rule: **extension** plugins depend on interfaces, never on the concrete loop
 | `fs-policy/` | `fs` | Policy gate plugin: observed-state + read-before-edit + version-guarded write/edit via the `fs/*` event gate | (no service — `fs/*` listeners) |
 | `tool-fs/` | `fs` | Model-facing `read`/`write`/`edit` tools + executor (reads via `ctx.fs`, owns read windowing, dispatches `fs/*`) | (registers on `ctx.tools`) |
 | `compact/` | `compact` | Abstract compaction seam + `compact/*` events + `CompactionResult` | `ctx.compact` |
-| `compact-basic/` | `compact` | A backend: char/4 estimation + token-budget retention + `llm.stream()` summarization | (registers `ctx.compact`) |
+| `compact-basic/` | `compact` | A backend: chars-per-token estimation (`charsPerToken`, default 4) + token-budget retention + `llm.stream()` summarization | (registers `ctx.compact`) |
 | `web/` | `web` | Abstract web seam (search/fetch provider registries + selection + vocabulary + `WebError`) | `ctx.web` |
 | `web-search-exa/` | `web` | Exa-backed `WebSearchProvider` | (registers on `ctx.web`) |
 | `web-search-perplexity/` | `web` | Perplexity-backed `WebSearchProvider` | (registers on `ctx.web`) |

packages/compact/README.md

@@ -5,7 +5,7 @@ A three-package capability seam (see [capability seams](../../docs/rfc/implement
 | Package | Role | ctx key |
 |---|---|---|
 | `compact/` | Abstract compaction seam (interface + `compact/*` events + `CompactionResult`) | `ctx.compact` |
-| `compact-basic/` | A backend: char/4 estimation + token-budget retention + `llm.stream()` summarization | (registers `ctx.compact`) |
+| `compact-basic/` | A backend: chars-per-token estimation (`charsPerToken`, default 4) + token-budget retention + `llm.stream()` summarization | (registers `ctx.compact`) |
 | `tool-compact/` (deferred) | Model-facing `/compact` tool over `ctx.compact` | (registers on `ctx.tools`) |
 
 The interface lives at `compact/compact/`, the backend at `compact/compact-basic/`. Unlike the bash seam, it depends on `dsh-session` and `dsh-llm` — its verbs are defined over a `Session` and its output is the `ContentBlock` vocabulary, so the contract cannot be expressed without naming them. That deviation from the "interface depends only on cordis" guidance is intentional and recorded in the [compaction capability-seam RFC](../../docs/rfc/implemented/feature/2026-06-18-compaction-capability-seam.md). A tokenizer- or template-based backend would replace `compact-basic` without touching the interface or the tool.

packages/compact/compact-basic/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@deepseek-ai/dsh-compact-basic",
-  "description": "Basic compaction backend (char/4 token estimation + token-budget retention + llm.generate() summarization) for the DeepSeek Harness",
+  "description": "Basic compaction backend (chars-per-token estimation + token-budget retention + llm.generate() summarization) for the DeepSeek Harness",
   "version": "0.0.1",
   "private": true,
   "type": "module",

packages/compact/compact/README.md

@@ -7,7 +7,7 @@ This package is the interface tier of the compaction capability, split so each c
 | Package | Role |
 |---|---|
 | `@deepseek-ai/dsh-compact` (this) | the interface: abstract service + `compact/*` events + `CompactionResult` |
-| `@deepseek-ai/dsh-compact-basic` (deferred) | a backend: char/4 estimation + token-budget retention + `llm.stream()` summarization |
+| `@deepseek-ai/dsh-compact-basic` (deferred) | a backend: chars-per-token estimation (`charsPerToken`, default 4) + token-budget retention + `llm.stream()` summarization |
 | `@deepseek-ai/dsh-tool-compact` (deferred) | the model-facing `/compact` tool over `ctx.compact` |
 
 Unlike the bash seam, this interface depends on `@deepseek-ai/dsh-session` and `@deepseek-ai/dsh-llm` — the contract's verbs are defined over a `Session` and its output is the `ContentBlock` vocabulary, so they cannot be expressed without naming those packages. That deviation from the "interface depends only on cordis" guidance is intentional and recorded in the [compaction capability-seam RFC](../../../docs/rfc/implemented/feature/2026-06-18-compaction-capability-seam.md).