diff --git a/docs/core-data-structures/web.md b/docs/core-data-structures/web.md
index 1adde3bd75..42797a8d99 100644
--- a/docs/core-data-structures/web.md
+++ b/docs/core-data-structures/web.md
@@ -10,7 +10,7 @@ Search and fetch share no request schema and no business logic, but they are del
 
 ## Search request and result
 
-The model-facing tool argument is just a `query`; `maxResults` is a consumer-owned bound (`dsh-tool-web`'s `WEB_SEARCH_MAX_RESULTS`, default `8`) passed through the seam and enforced on the way back — if a provider over-returns, the seam truncates `sources[]` and sets `truncated`.
+The model-facing tool argument is just a `query`; `maxResults` is a consumer-owned bound (`dsh-tool-web`'s `searchMaxResults` config, default `8`) passed through the seam and enforced on the way back — if a provider over-returns, the seam truncates `sources[]` and sets `truncated`.
 
 ```ts type-equiv
 interface WebSearchRequest {
diff --git a/docs/rfc/implemented/architecture/2026-06-24-web-capability-seam.md b/docs/rfc/implemented/architecture/2026-06-24-web-capability-seam.md
index 55ada9d576..833cbeebb5 100644
--- a/docs/rfc/implemented/architecture/2026-06-24-web-capability-seam.md
+++ b/docs/rfc/implemented/architecture/2026-06-24-web-capability-seam.md
@@ -175,7 +175,7 @@ The first `web_search` model-facing tool should be small. The only model-facing
 
 - `query`: required string.
 
-`max_results` is NOT exposed to the model in the first version. It is a `dsh-tool-web`-layer decision: the tool sets the result bound — a default of `8` (aligning with OpenCode's Exa default), as an exported constant mirroring `dsh-tool-fs`'s `READ_LIMIT` / `GREP_LIMIT` — and passes it to the seam as `maxResults` on the `WebSearchRequest`. Keeping it off the model schema means the model just asks a question and the product controls how much context comes back; the field can be promoted to a model-facing argument later without breaking the seam.
+`max_results` is NOT exposed to the model in the first version. It is a `dsh-tool-web`-layer decision: the tool sets the result bound — the `searchMaxResults` plugin config, default `8` (aligning with OpenCode's Exa default), mirroring `dsh-tool-fs`'s `readLimit` — and passes it to the seam as `maxResults` on the `WebSearchRequest`. Keeping it off the model schema means the model just asks a question and the product controls how much context comes back; the field can be promoted to a model-facing argument later without breaking the seam.
 
 `maxResults` flows tool → seam → provider, and the bound is enforced on the way back:
 
diff --git a/docs/rfc/proposed/simplification/2026-07-04-prune-write-only-fs-surface.md b/docs/rfc/proposed/simplification/2026-07-04-prune-write-only-fs-surface.md
index 0a4bc14d89..604c1774d5 100644
--- a/docs/rfc/proposed/simplification/2026-07-04-prune-write-only-fs-surface.md
+++ b/docs/rfc/proposed/simplification/2026-07-04-prune-write-only-fs-surface.md
@@ -6,7 +6,7 @@ Status: proposed
 
 The [fs seam split](../../implemented/simplification/2026-06-26-fsspec-style-fs-seam.md) moved read routing and policy out of the backend into `dsh-tool-fs` and `dsh-fs-policy`. Four pieces of surface kept the pre-split shape — populated on every call, read by nobody:
 
-1. **`STREAM_MIN_SIZE` + `FsIoInternals.streamMinSize` in `dsh-fs-local`** (`packages/fs/fs-local/src/fsio.ts`, re-exported from `packages/fs/fs-local/src/index.ts`): zero readers anywhere, including fs-local's own source and tests. The backend has no read routing — `readWholeText`/`streamWholeText` are separate primitives the caller chooses between — and the real routing constant lives in the consumer (`packages/fs/tool-fs/src/read.ts`, compared against `info.size`). Two mirrors of the 10 MiB fact; the backend's is dead, and the knob's JSDoc claims a "read routing" override that does not exist.
+1. **`STREAM_MIN_SIZE` + `FsIoInternals.streamMinSize` in `dsh-fs-local`** — *already removed by the no-hardcoded-tunables audit (the routing bound became `dsh-tool-fs`'s `readStreamMinSize` config); listed here for the record of the full prune, no work remains.* Originally (`packages/fs/fs-local/src/fsio.ts`, re-exported from `packages/fs/fs-local/src/index.ts`): zero readers anywhere, including fs-local's own source and tests. The backend has no read routing — `readWholeText`/`streamWholeText` are separate primitives the caller chooses between — and the real routing constant lives in the consumer (`packages/fs/tool-fs/src/read.ts`, compared against `info.size`). Two mirrors of the 10 MiB fact; the backend's is dead, and the knob's JSDoc claims a "read routing" override that does not exist.
 2. **`FsTarget.inputPath`** (`packages/fs/fs/src/types.ts`): every backend and every test fake must fabricate a "diagnostics only" value with zero production readers — the policy plugin and every error message use `targetKey`/`displayPath`. The `listDir` producer exposes the semantic wobble: directory children get the bare entry name, which was nobody's "input".
 3. **`FsEditOutcome.replacements` + `.replaceAll`** (`packages/fs/fs/src/types.ts`): `replacements` has zero production readers (the single-match policy itself stays — it is enforced by the `FS_AMBIGUOUS_EDIT`/`FS_EDIT_NOT_FOUND` throws inside the backend, whose error message keeps the internal count); `replaceAll` is read only by `formatEditOutput` in `packages/fs/tool-fs/src/edit.ts` — as an echo of the `replace_all` argument the tool already holds. Shrunk, `FsEditOutcome` becomes `{ version, before, after }`, parallel to `FsWriteOutcome`'s genuinely backend-discovered fields.
 4. **`FileReadOutcome.limit` + `.version`** (`packages/fs/tool-fs/src/read-render.ts`): populated by the read tool, but `formatReadOutput` renders `offset`/`lines`/`totalLines`/`truncatedByBytes` only, and the `fs/observed` emit uses `info.version` directly rather than the outcome copy.
diff --git a/packages/bash/bash-local/README.md b/packages/bash/bash-local/README.md
index 109debc24c..c13a3ab923 100644
--- a/packages/bash/bash-local/README.md
+++ b/packages/bash/bash-local/README.md
@@ -12,6 +12,7 @@ Local-subprocess implementation of the `@deepseek-ai/dsh-bash` executor seam: `L
     timeoutMs: 120000          # default foreground timeout
     maxTimeoutMs: 600000       # cap for per-call overrides
     maxOutputBytes: 64000      # per-stream in-memory cap; overflow spills to disk
+    graceMs: 3000              # SIGTERM→SIGKILL escalation grace on kills
 ```
 
 ## Behavior (and where it came from)
@@ -19,7 +20,7 @@ Local-subprocess implementation of the `@deepseek-ai/dsh-bash` executor seam: `L
 Design surveyed against the bash tools of Claude Code, OpenCode, Codex, and pi; the notable choices:
 
 - **Spawn per call, no shell state** — every call is a fresh non-login `bash -c` (deterministic; no rc files). All four surveyed tools spawn per call. `XXX(stateful-shell)` in `src/run.ts` records the two proven stateful designs (Claude Code's cwd-only persistence; Codex's PTY exec sessions) for when real workflows demand them.
-- **Process-group kills with escalation** — children are spawned `detached` (own process group); kills send SIGTERM to the group, then SIGKILL after a 3s grace (OpenCode's escalation; pipelines and subshells die with the parent). ESRCH is tolerated; daemons that re-parent away from the group can still survive — same caveat as the surveyed tools.
+- **Process-group kills with escalation** — children are spawned `detached` (own process group); kills send SIGTERM to the group, then SIGKILL after the `graceMs` grace (default 3s — OpenCode's escalation; pipelines and subshells die with the parent). ESRCH is tolerated; daemons that re-parent away from the group can still survive — same caveat as the surveyed tools.
 - **Tail-keep truncation + spill files** — output beyond `maxOutputBytes` keeps the in-memory TAIL (errors/results cluster at the end — pi/OpenCode rationale) while the FULL stream is appended to a temp file whose path is reported when available. If the final spill close reports a delayed writeback failure, the executor still returns the tail but withholds the path rather than advertising a possibly incomplete file.
 - **Model-friendly env + credential scrub** — `process.env` minus credential-shaped vars (`*KEY*`/`*SECRET*`/`*TOKEN*`), then `NO_COLOR=1 TERM=dumb PAGER=cat GIT_PAGER=cat` (Codex's hardcoded set) so pagers and ANSI color don't garble results. This scrub is the security control that keeps the harness's *ambient* credentials out of a spawned command. A spec's `env` is merged LAST (after the scrub), so a caller's explicit entry — a value it already holds — wins even on a credential-shaped name. The spec's `stdin`, when supplied, is written to the child and closed; with none supplied, fd 0 is `/dev/null` — the exact pre-seam default, so a command that probes stdin's file type is unaffected. Both `env`/`stdin` are set by in-process plugins (the hooks bridges); the model-facing tool doesn't expose them. See [the bash-stdin-env RFC](../../../docs/rfc/implemented/architecture/2026-06-30-bash-stdin-env-trusted-plugin-surface.md).
 - **Background tasks** — `start()` returns immediately, no timeout applies (Claude Code detaches timeouts when backgrounding), `readOutput()` is incremental with whole-stream byte offsets, and disposal kills everything. The spec's opaque `owner` token is stored on the tracked task and returned by `ownerOf(id)` — the executor never interprets it (the consumer's access policy does), and because it lives with the task here it survives a `tool-bash` HMR reload.
diff --git a/packages/bash/bash-local/src/index.ts b/packages/bash/bash-local/src/index.ts
index af4c47e71e..6df7b3da7b 100644
--- a/packages/bash/bash-local/src/index.ts
+++ b/packages/bash/bash-local/src/index.ts
@@ -17,7 +17,7 @@ import { Context } from 'cordis'
 import z from 'schemastery'
 import { BashExecutor, BashTaskId } from '@deepseek-ai/dsh-bash'
 import type { BashExecRequest, BashExecSpec, BashRunResult, BashTask, BashTaskRead, OwnerToken } from '@deepseek-ai/dsh-bash'
-import { runBash } from './run.ts'
+import { DEFAULT_GRACE_MS, runBash } from './run.ts'
 import type { RunInternals, RunningBash } from './run.ts'
 
 export { DEFAULT_GRACE_MS, ENV_OVERRIDES, killGroup, OutputCollector, runBash } from './run.ts'
@@ -33,6 +33,8 @@ export interface Config {
   maxTimeoutMs?: number
   /** Per-stream in-memory output cap; overflow spills to a temp file. */
   maxOutputBytes?: number
+  /** Grace period between the SIGTERM and the SIGKILL escalation on a kill. */
+  graceMs?: number
 }
 
 /** The shape after schemastery applied the defaults (cwd has none). */
@@ -57,7 +59,7 @@ interface TrackedTask extends BashTask {
  * Local-subprocess bash executor. Defaults follow the agent-tool survey
  * consensus: 120s default / 600s max timeout (Claude Code, OpenCode), 64KB
  * in-memory output with full-stream spill files (pi, OpenCode),
- * process-group SIGTERM→SIGKILL kills (OpenCode).
+ * process-group SIGTERM→SIGKILL kills with a 3s grace (OpenCode).
  */
 export class LocalBashExecutor extends BashExecutor {
   static Config: z<Config> = z.object({
@@ -65,11 +67,12 @@ export class LocalBashExecutor extends BashExecutor {
     timeoutMs: z.number().default(120_000),
     maxTimeoutMs: z.number().default(600_000),
     maxOutputBytes: z.number().default(64_000),
+    graceMs: z.number().default(DEFAULT_GRACE_MS),
   })
 
   private tasks = new Map<BashTaskId, TrackedTask>()
   private nextTaskId = 1
-  /** Test seam: timer/spill knobs forwarded to runBash. */
+  /** Test seam: spill knobs forwarded to runBash. */
   internals: RunInternals = {}
 
   /** Validated config (schemastery applied the defaults before construction). */
@@ -83,6 +86,7 @@ export class LocalBashExecutor extends BashExecutor {
     assertPositiveFinite('timeoutMs', this.config.timeoutMs)
     assertPositiveFinite('maxTimeoutMs', this.config.maxTimeoutMs)
     assertPositiveFinite('maxOutputBytes', this.config.maxOutputBytes)
+    assertPositiveFinite('graceMs', this.config.graceMs)
     ctx.effect(() => async () => {
       // Kill every live process group and WAIT for the processes to close so
       // nothing outlives the fiber (HMR safety) — a TERM-trapping child is
@@ -132,6 +136,7 @@ export class LocalBashExecutor extends BashExecutor {
       cwd: spec.workdir,
       timeoutMs: spec.timeoutMs,
       maxOutputBytes: this.config.maxOutputBytes,
+      graceMs: this.config.graceMs,
       signal: spec.signal,
       stdin: spec.stdin,
       env: spec.env,
@@ -150,6 +155,7 @@ export class LocalBashExecutor extends BashExecutor {
       cwd: spec.workdir,
       timeoutMs: 0,
       maxOutputBytes: this.config.maxOutputBytes,
+      graceMs: this.config.graceMs,
       signal: spec.signal,
       stdin: spec.stdin,
       env: spec.env,
diff --git a/packages/bash/bash-local/src/run.ts b/packages/bash/bash-local/src/run.ts
index 023ea0e3d1..489d380787 100644
--- a/packages/bash/bash-local/src/run.ts
+++ b/packages/bash/bash-local/src/run.ts
@@ -73,6 +73,8 @@ export interface SpawnSpec {
   timeoutMs: number
   /** Per-stream in-memory cap; overflow spills to disk (tail kept in memory). */
   maxOutputBytes: number
+  /** Grace period between the SIGTERM and the SIGKILL escalation on a kill. */
+  graceMs: number
   /** Abort signal — kills the process group when fired. */
   signal?: AbortSignal | undefined
   /**
@@ -100,15 +102,13 @@ export interface SpawnOutcome {
   stderr: CollectedOutput
 }
 
-/** Injectable knobs so tests can exercise escalation/spill without long waits. */
+/** Injectable knobs so tests can exercise spill behavior without the OS tmpdir. */
 export interface RunInternals {
-  /** Grace period between SIGTERM and SIGKILL on the process group. */
-  graceMs?: number
   /** Directory for spill files (defaults to the OS temp dir). */
   spillDir?: string
 }
 
-/** Default SIGTERM→SIGKILL grace period (matches OpenCode's 3s). */
+/** Default SIGTERM→SIGKILL grace period (the `graceMs` config; matches OpenCode's 3s). */
 export const DEFAULT_GRACE_MS = 3_000
 
 let spillCounter = 0
@@ -292,7 +292,6 @@ export interface RunningBash {
  * no inherited shell state); revisit when real workflows demand it.
  */
 export function runBash(spec: SpawnSpec, internals: RunInternals = {}): RunningBash {
-  const graceMs = internals.graceMs ?? DEFAULT_GRACE_MS
   const spillDir = internals.spillDir ?? privateSpillDir()
 
   if (spec.signal?.aborted) {
@@ -331,7 +330,7 @@ export function runBash(spec: SpawnSpec, internals: RunInternals = {}): RunningB
   const kill = (): void => {
     if (graceTimer !== undefined) return // escalation already in flight
     killGroup(pid, 'SIGTERM')
-    graceTimer = setTimeout(() => { killGroup(pid, 'SIGKILL') }, graceMs)
+    graceTimer = setTimeout(() => { killGroup(pid, 'SIGKILL') }, spec.graceMs)
   }
 
   if (spec.timeoutMs > 0) {
diff --git a/packages/bash/bash-local/tests/executor.spec.ts b/packages/bash/bash-local/tests/executor.spec.ts
index cf6d1c267e..ce89b2a0ae 100644
--- a/packages/bash/bash-local/tests/executor.spec.ts
+++ b/packages/bash/bash-local/tests/executor.spec.ts
@@ -11,9 +11,10 @@ const spillDir = mkdtempSync(join(tmpdir(), 'dsh-bash-exec-spec-'))
 
 async function setup(config: ConstructorParameters<typeof LocalBashExecutor>[1] = {}) {
   const ctx = new Context()
-  await ctx.plugin(LocalBashExecutor, config)
+  // A short kill grace via the REAL config path, so escalation tests stay fast.
+  await ctx.plugin(LocalBashExecutor, { graceMs: 200, ...config })
   const bash = ctx.bash as LocalBashExecutor
-  bash.internals = { spillDir, graceMs: 200 }
+  bash.internals = { spillDir }
   return { ctx, bash }
 }
 
@@ -80,12 +81,22 @@ describe('LocalBashExecutor.run', () => {
     await expect(setup({ timeoutMs: Number.NaN })).rejects.toThrow(/timeoutMs/)
     await expect(setup({ maxTimeoutMs: 0 })).rejects.toThrow(/maxTimeoutMs/)
     await expect(setup({ maxOutputBytes: -1 })).rejects.toThrow(/maxOutputBytes/)
+    await expect(setup({ graceMs: 0 })).rejects.toThrow(/graceMs/)
 
     const { bash } = await setup()
     expect(() => bash.resolve({ command: 'true', timeoutMs: Number.NaN })).toThrow(/request\.timeoutMs/)
     expect(() => bash.resolve({ command: 'true', timeoutMs: -1 })).toThrow(/request\.timeoutMs/)
   })
 
+  it('kill escalation uses the configured graceMs (a TERM-trapping task dies by SIGKILL)', async () => {
+    const { bash } = await setup() // setup pins graceMs: 200 via config
+    const task = bash.start(bash.resolve({ command: 'trap \'\' TERM; sleep 60' }))
+    await new Promise(resolve => setTimeout(resolve, 100))
+    bash.kill(task.id)
+    await task.done
+    expect(task.signal).toBe('SIGKILL')
+  })
+
   it('per-call timeout takes precedence under the cap and kills on expiry', async () => {
     const { bash } = await setup({ timeoutMs: 60_000 })
     const result = await bash.run(bash.resolve({ command: 'sleep 60', timeoutMs: 100 }))
@@ -271,9 +282,9 @@ describe('LocalBashExecutor background tasks', () => {
 
   it('disposing with already-finished tasks only kills the running ones', async () => {
     const ctx = new Context()
-    const fiber = await ctx.plugin(LocalBashExecutor, {})
+    const fiber = await ctx.plugin(LocalBashExecutor, { graceMs: 200 })
     const bash = ctx.bash as LocalBashExecutor
-    bash.internals = { spillDir, graceMs: 200 }
+    bash.internals = { spillDir }
 
     const finished = bash.start(bash.resolve({ command: 'true' }))
     await finished.done
@@ -288,9 +299,9 @@ describe('LocalBashExecutor background tasks', () => {
 
   it('disposing the executor fiber kills running tasks (no orphans)', async () => {
     const ctx = new Context()
-    const fiber = await ctx.plugin(LocalBashExecutor, {})
+    const fiber = await ctx.plugin(LocalBashExecutor, { graceMs: 200 })
     const bash = ctx.bash as LocalBashExecutor
-    bash.internals = { spillDir, graceMs: 200 }
+    bash.internals = { spillDir }
     const listener = vi.fn()
     bash.onTaskDone(listener)
 
@@ -337,9 +348,9 @@ describe('review fixes: lifecycle hardening', () => {
 
   it('dispose AWAITS a TERM-trapping process (SIGKILL escalation included)', async () => {
     const ctx = new Context()
-    const fiber = await ctx.plugin(LocalBashExecutor, {})
+    const fiber = await ctx.plugin(LocalBashExecutor, { graceMs: 200 })
     const bash = ctx.bash as LocalBashExecutor
-    bash.internals = { spillDir, graceMs: 200 }
+    bash.internals = { spillDir }
 
     const task = bash.start(bash.resolve({ command: 'trap \'\' TERM; sleep 60' }))
     await new Promise(resolve => setTimeout(resolve, 100))
diff --git a/packages/bash/bash-local/tests/run.spec.ts b/packages/bash/bash-local/tests/run.spec.ts
index 3a1ff7c2c5..d2888e2fee 100644
--- a/packages/bash/bash-local/tests/run.spec.ts
+++ b/packages/bash/bash-local/tests/run.spec.ts
@@ -28,6 +28,7 @@ function spec(command: string, overrides: Partial<Parameters<typeof runBash>[0]>
     cwd: process.cwd(),
     timeoutMs: 0,
     maxOutputBytes: 64_000,
+    graceMs: 3_000,
     ...overrides,
   }
 }
@@ -106,7 +107,7 @@ describe('runBash', () => {
   })
 
   it('escalates to SIGKILL when SIGTERM is trapped', async () => {
-    const running = runBash(spec('trap \'\' TERM; echo ready; sleep 60'), { graceMs: 200 })
+    const running = runBash(spec('trap \'\' TERM; echo ready; sleep 60', { graceMs: 200 }))
     await waitForStdout(running, 'ready\n')
     running.kill()
     const result = await running.done
diff --git a/packages/bash/tool-bash/tests/tools.spec.ts b/packages/bash/tool-bash/tests/tools.spec.ts
index 82b69fb133..a01bdc0c86 100644
--- a/packages/bash/tool-bash/tests/tools.spec.ts
+++ b/packages/bash/tool-bash/tests/tools.spec.ts
@@ -21,8 +21,8 @@ async function setup() {
   await ctx.plugin(SystemPrompt)
   await ctx.plugin(ToolRegistry)
   await ctx.plugin(AgentRegistry)
-  await ctx.plugin(LocalBashExecutor, { timeoutMs: 10_000 })
-  ;(ctx.bash as LocalBashExecutor).internals = { spillDir, graceMs: 200 }
+  await ctx.plugin(LocalBashExecutor, { timeoutMs: 10_000, graceMs: 200 })
+  ;(ctx.bash as LocalBashExecutor).internals = { spillDir }
   await ctx.plugin(ToolBash)
   return ctx
 }
@@ -184,8 +184,8 @@ describe('bash tool', () => {
     const ctx = new Context()
     await ctx.plugin(SystemPrompt)
     await ctx.plugin(ToolRegistry)
-    await ctx.plugin(LocalBashExecutor, { maxOutputBytes: 100 })
-    ;(ctx.bash as LocalBashExecutor).internals = { spillDir, graceMs: 200 }
+    await ctx.plugin(LocalBashExecutor, { maxOutputBytes: 100, graceMs: 200 })
+    ;(ctx.bash as LocalBashExecutor).internals = { spillDir }
     await ctx.plugin(ToolBash)
     const result = await call(ctx, 'bash', { command: 'for i in $(seq 1 100); do printf "line-%04d\\n" $i; done', description: 'test command' })
     expect(text(result)).toContain('[output truncated; full output: ')
@@ -316,8 +316,8 @@ describe('background tools', () => {
     const ctx = new Context()
     await ctx.plugin(SystemPrompt)
     await ctx.plugin(ToolRegistry)
-    await ctx.plugin(LocalBashExecutor, { maxOutputBytes: 100 })
-    ;(ctx.bash as LocalBashExecutor).internals = { spillDir, graceMs: 200 }
+    await ctx.plugin(LocalBashExecutor, { maxOutputBytes: 100, graceMs: 200 })
+    ;(ctx.bash as LocalBashExecutor).internals = { spillDir }
     await ctx.plugin(ToolBash)
 
     const started = await call(ctx, 'bash', { command: 'for i in $(seq 1 200); do printf "line-%04d\\n" $i; done', description: 'test command', run_in_background: true })
@@ -568,8 +568,8 @@ describe('background task ownership (cross-session isolation)', () => {
     const ctx = new Context()
     await ctx.plugin(SystemPrompt)
     await ctx.plugin(ToolRegistry)
-    await ctx.plugin(LocalBashExecutor, { timeoutMs: 10_000 })
-    ;(ctx.bash as LocalBashExecutor).internals = { spillDir, graceMs: 200 }
+    await ctx.plugin(LocalBashExecutor, { timeoutMs: 10_000, graceMs: 200 })
+    ;(ctx.bash as LocalBashExecutor).internals = { spillDir }
     const fiber = await ctx.plugin(ToolBash)
 
     const a = fakeAgent('sess-a')
diff --git a/packages/compact/compact-basic/README.md b/packages/compact/compact-basic/README.md
index c195ae42fb..cbd1146634 100644
--- a/packages/compact/compact-basic/README.md
+++ b/packages/compact/compact-basic/README.md
@@ -32,6 +32,7 @@ Every knob is **required** except `auto` — there is no concrete data yet to ju
 | `maxTokens` | yes | Provider generation cap for the summarization call; may include reasoning tokens. |
 | `compactionRetries` | yes | Extra compaction attempts after the first if the compacted surface remains over threshold. |
 | `auto` | no (default `true`) | Register the `agent/pre-step` auto-compaction listener. Set `false` for manual-only. |
+| `charsPerToken` | no (default `4`) | Token-estimator text density (estimated tokens = chars / `charsPerToken`; may be fractional). The default suits English text; CJK-heavy deployments should set ~1-2 or the estimate undershoots several-fold and compaction fires too late. |
 
 ## Usage
 
diff --git a/packages/compact/compact-basic/src/index.ts b/packages/compact/compact-basic/src/index.ts
index f53dace461..26c593a47f 100644
--- a/packages/compact/compact-basic/src/index.ts
+++ b/packages/compact/compact-basic/src/index.ts
@@ -148,9 +148,11 @@ function finishError(finish: FinishReason): Error | undefined {
 }
 
 /**
- * Basic, dependency-light compaction backend. Defaults target a 128K context
- * window, compacting at 80% utilization and retaining ~20K tokens of recent
- * context.
+ * Basic, dependency-light compaction backend: estimates the surface's token
+ * footprint, summarizes the stale prefix through the model, and shadows it
+ * behind a durable checkpoint. Every threshold/budget knob is required config
+ * ({@link BasicCompactConfig}); the estimator's text density is the
+ * `charsPerToken` knob.
  */
 export class BasicCompactService extends CompactService {
   static inject = ['llm']
@@ -207,24 +209,27 @@ export class BasicCompactService extends CompactService {
 
   // ---- Token estimation (overridable hooks) ----
 
-  // TODO: char/4 is a coarse heuristic. Replace with an exact count — a real
-  // tokenizer, or the provider's post-response `usage` (input tokens) fed back
-  // as a correction — so threshold decisions match the model's actual budget.
+  // TODO: chars/charsPerToken is a coarse heuristic. Replace with an exact
+  // count — a real tokenizer, or the provider's post-response `usage` (input
+  // tokens) fed back as a correction — so threshold decisions match the
+  // model's actual budget.
   /**
-   * Estimate the token count of content blocks — char/4 with per-block
-   * overhead. Override in a subclass to plug in a real tokenizer.
+   * Estimate the token count of content blocks — chars divided by the
+   * `charsPerToken` config, with per-block overhead. Override in a subclass to
+   * plug in a real tokenizer.
    */
   estimateContentTokens(blocks: readonly ContentBlock[]): number {
+    const { charsPerToken } = this.config
     let tokens = 0
     for (const block of blocks) {
       switch (block.type) {
         case 'text':
         case 'reasoning':
-          tokens += Math.ceil(block.text.length / 4) + BLOCK_OVERHEAD
+          tokens += Math.ceil(block.text.length / charsPerToken) + BLOCK_OVERHEAD
           break
         case 'tool-call':
-          tokens += Math.ceil(block.name.length / 4)
-            + Math.ceil(block.arguments.length / 4)
+          tokens += Math.ceil(block.name.length / charsPerToken)
+            + Math.ceil(block.arguments.length / charsPerToken)
             + BLOCK_OVERHEAD
           break
         case 'tool-result':
@@ -236,7 +241,7 @@ export class BasicCompactService extends CompactService {
         default:
           // Unknown block types (merge-extensible ContentBlockMap):
           // estimate conservatively via JSON stringify.
-          tokens += BLOCK_OVERHEAD + Math.ceil(JSON.stringify(block).length / 4)
+          tokens += BLOCK_OVERHEAD + Math.ceil(JSON.stringify(block).length / charsPerToken)
       }
     }
     return tokens
@@ -266,7 +271,7 @@ export class BasicCompactService extends CompactService {
       total += this.estimateContentTokens(msg.content)
       total += ROLE_OVERHEAD
     }
-    if (systemPrompt) total += Math.ceil(systemPrompt.length / 4)
+    if (systemPrompt) total += Math.ceil(systemPrompt.length / this.config.charsPerToken)
     return total
   }
 
diff --git a/packages/compact/compact-basic/src/types.ts b/packages/compact/compact-basic/src/types.ts
index 98195d8883..2f10084ac3 100644
--- a/packages/compact/compact-basic/src/types.ts
+++ b/packages/compact/compact-basic/src/types.ts
@@ -10,10 +10,12 @@
  */
 
 /**
- * Backend configuration. Every knob is REQUIRED except `auto`: there is no
- * concrete data yet to justify default thresholds/budgets, so a consumer must
- * state each value explicitly rather than inherit a guessed default. `auto`
- * alone defaults to `true` (auto-compaction is the intended posture).
+ * Backend configuration. Every knob is REQUIRED except `auto` and
+ * `charsPerToken`: there is no concrete data yet to justify default
+ * thresholds/budgets, so a consumer must state each value explicitly rather
+ * than inherit a guessed default. `auto` alone defaults to `true`
+ * (auto-compaction is the intended posture), and `charsPerToken` defaults to
+ * the English-text heuristic its estimator was calibrated on.
  */
 export interface BasicCompactConfig {
   /** Context window size in tokens. */
@@ -30,13 +32,21 @@ export interface BasicCompactConfig {
   compactionRetries: number
   /** Enable automatic compaction on the `agent/pre-step` seam (default true). */
   auto?: boolean
+  /**
+   * Text density for the token estimator: estimated tokens = chars /
+   * `charsPerToken`. Defaults to 4 (typical English text). A CJK-heavy
+   * deployment should set ~1-2 — CJK runs at roughly 1-2 chars per token, so
+   * the default UNDERestimates several-fold and compaction fires far too late.
+   * May be fractional.
+   */
+  charsPerToken?: number
 }
 
-/** Resolved config with `auto` defaulted. */
+/** Resolved config with `auto` and `charsPerToken` defaulted. */
 export type ResolvedConfig = Required<BasicCompactConfig>
 
 /**
- * Default `auto` when unset and reject nonsensical numeric knobs.
+ * Default `auto`/`charsPerToken` when unset and reject nonsensical numeric knobs.
  *
  * Convergence is not a static config invariant: provider generation caps can be
  * spent on hidden or surfaced reasoning tokens, and the model may emit a summary
@@ -46,13 +56,14 @@ export type ResolvedConfig = Required<BasicCompactConfig>
  * throwing if the surface still exceeds the threshold.
  */
 export function resolveConfig(config: BasicCompactConfig): ResolvedConfig {
-  const resolved: ResolvedConfig = { auto: true, ...config }
+  const resolved: ResolvedConfig = { auto: true, charsPerToken: 4, ...config }
 
   assertPositiveInteger('contextWindow', resolved.contextWindow)
   assertRatio('thresholdRatio', resolved.thresholdRatio)
   assertNonNegativeInteger('retainTokens', resolved.retainTokens)
   assertPositiveInteger('maxTokens', resolved.maxTokens)
   assertNonNegativeInteger('compactionRetries', resolved.compactionRetries)
+  assertPositiveFinite('charsPerToken', resolved.charsPerToken)
   if (typeof resolved.summarizationModel !== 'string') {
     throw new Error('BasicCompactConfig: summarizationModel must be a string.')
   }
@@ -74,6 +85,12 @@ function assertNonNegativeInteger(name: string, value: number): void {
   }
 }
 
+function assertPositiveFinite(name: string, value: number): void {
+  if (typeof value !== 'number' || !Number.isFinite(value) || value <= 0) {
+    throw new Error(`BasicCompactConfig: ${name} (${value}) must be a positive finite number.`)
+  }
+}
+
 function assertRatio(name: string, value: number): void {
   if (typeof value !== 'number' || !Number.isFinite(value) || value <= 0 || value > 1) {
     throw new Error(`BasicCompactConfig: ${name} (${value}) must be a number in (0, 1].`)
diff --git a/packages/compact/compact-basic/tests/compact-basic.spec.ts b/packages/compact/compact-basic/tests/compact-basic.spec.ts
index 1929e656be..7d5d67b6db 100644
--- a/packages/compact/compact-basic/tests/compact-basic.spec.ts
+++ b/packages/compact/compact-basic/tests/compact-basic.spec.ts
@@ -820,6 +820,19 @@ describe('BasicCompactService token estimation (char/4 heuristic)', () => {
     const svc = new BasicCompactService(new Context(), cfg({ auto: false }))
     expect(svc.estimateContentTokens([])).toBe(0)
   })
+
+  it('honors a configured charsPerToken (fractional densities included)', () => {
+    // 'this is a somewhat longer text block' = 36 chars.
+    const blocks: ContentBlock[] = [{ type: 'text', text: 'this is a somewhat longer text block' }]
+    // charsPerToken 2: ceil(36/2)+4 = 22 — a CJK-density config doubles the estimate.
+    const dense = new BasicCompactService(new Context(), cfg({ auto: false, charsPerToken: 2 }))
+    expect(dense.estimateContentTokens(blocks)).toBe(22)
+    // Fractional density is legal: ceil(36/1.5)+4 = 28.
+    const fractional = new BasicCompactService(new Context(), cfg({ auto: false, charsPerToken: 1.5 }))
+    expect(fractional.estimateContentTokens(blocks)).toBe(28)
+    // The system-prompt term scales with the same knob: 36-char prompt at density 2 → ceil(36/2) = 18.
+    expect(dense.estimateTokens([], 'this is a somewhat longer text block')).toBe(18)
+  })
 })
 
 describe('BasicCompactService HMR safety', () => {
@@ -862,6 +875,10 @@ describe('BasicCompactService config validation', () => {
     )).toThrow(/summarizationModel must be a string/)
     expect(() => new BasicCompactService(new Context(), cfg({ auto: 'no' } as unknown as Partial<BasicCompactConfig>)))
       .toThrow(/auto must be a boolean/)
+    expect(() => new BasicCompactService(new Context(), cfg({ auto: false, charsPerToken: 0 })))
+      .toThrow(/charsPerToken .* positive finite number/)
+    expect(() => new BasicCompactService(new Context(), cfg({ auto: false, charsPerToken: Number.NaN })))
+      .toThrow(/charsPerToken .* positive finite number/)
   })
 
   it('accepts a large retain budget because convergence is enforced dynamically', () => {
diff --git a/packages/fs/fs-local/src/fsio.ts b/packages/fs/fs-local/src/fsio.ts
index 980cb4764d..64754b2dd4 100644
--- a/packages/fs/fs-local/src/fsio.ts
+++ b/packages/fs/fs-local/src/fsio.ts
@@ -26,9 +26,6 @@ import { basename, dirname, join, resolve } from 'node:path'
 import { TextDecoder } from 'node:util'
 import { FsError, FsTargetKey, FsVersion } from '@deepseek-ai/dsh-fs'
 
-/** Files at or above this size stream their text; smaller files read whole. */
-export const STREAM_MIN_SIZE = 10 * 1024 * 1024
-
 const BINARY_SAMPLE_BYTES = 8192
 
 function isENOENT(error: unknown): boolean {
@@ -85,13 +82,10 @@ function versionOf(info: Stats): FsVersion {
 }
 
 /**
- * Test seam: lets specs force the streaming read path (via a small
- * `streamMinSize`) and pin the temp-file name (to prove exclusive-open
- * behavior) without a 10 MB fixture or a name race.
+ * Test seam: lets specs pin the temp-file name (to prove exclusive-open
+ * behavior) without a name race.
  */
 export interface FsIoInternals {
-  /** Override {@link STREAM_MIN_SIZE} for read routing. */
-  streamMinSize?: number
   /** Override the generated private staging-dir name (relative to the target dir). */
   tempDirName?: (writePath: string) => string
   /** Override the generated temp-file name (relative to the private staging dir). */
diff --git a/packages/fs/fs-local/src/index.ts b/packages/fs/fs-local/src/index.ts
index af74847ed1..abd8d047e6 100644
--- a/packages/fs/fs-local/src/index.ts
+++ b/packages/fs/fs-local/src/index.ts
@@ -41,7 +41,6 @@ import {
 import type { FsIoInternals } from './fsio.ts'
 
 export {
-  STREAM_MIN_SIZE,
   applyLiteralEdit,
   listDirectory,
   probe,
diff --git a/packages/fs/tool-fs/README.md b/packages/fs/tool-fs/README.md
index dacef45590..fedd1ff7a2 100644
--- a/packages/fs/tool-fs/README.md
+++ b/packages/fs/tool-fs/README.md
@@ -11,11 +11,22 @@ await ctx.plugin(ToolFs)                                  // this package — re
 
 `@deepseek-ai/dsh-fs-policy` is **optional**: omit it and the tools run against the bare provider (unconditional write/overwrite/edit, no observed-state). A deployment that loads these tools is expected to also load it, so the behavior is read-before-write/edit.
 
+## Config
+
+All keys are optional; the defaults are the shipped read caps.
+
+| Key | Default | Meaning |
+|---|---|---|
+| `readLimit` | `2000` | Default and maximum lines returned by one `read` call (the tool schema advertises it as the `limit` default). |
+| `readMaxLineLength` | `2000` | Characters kept per line before truncation (the suffix names the cap). |
+| `readMaxBytes` | `51200` | Byte cap on one `read` call's selected lines; overflow ends the window with a "capped" footer. |
+| `readStreamMinSize` | `10485760` | Files at or above this size (or with unknown size) stream instead of loading whole into memory. |
+
 ## Tools (schemas per [the filesystem tool schemas RFC](../../../docs/rfc/implemented/feature/2026-06-17-filesystem-tool-schemas.md))
 
 | Tool | Arguments | Behavior |
 |---|---|---|
-| `read` | `file_path`, `offset?`, `limit?` | Line-numbered UTF-8 content with a pagination footer. `offset` is 1-based; `limit` defaults to and caps at 2000 lines. |
+| `read` | `file_path`, `offset?`, `limit?` | Line-numbered UTF-8 content with a pagination footer. `offset` is 1-based; `limit` defaults to and caps at the configured `readLimit` (2000). |
 | `write` | `file_path`, `content` | Create or fully replace a file. With the policy plugin: overwriting an existing file requires a prior `read` at the unchanged version; creating a new file does not. Without it: unconditional. |
 | `edit` | `file_path`, non-empty `old_string`, `new_string`, `replace_all?` | Literal replacement; unique match required unless `replace_all` is true. With the policy plugin: requires a prior `read` (any window) and the file unchanged since. Without it: unconditional. |
 
diff --git a/packages/fs/tool-fs/package.json b/packages/fs/tool-fs/package.json
index a7f71ce6fa..7e7b78aa38 100644
--- a/packages/fs/tool-fs/package.json
+++ b/packages/fs/tool-fs/package.json
@@ -22,7 +22,8 @@
   ],
   "license": "BSD-3-Clause",
   "dependencies": {
-    "diff": "^9.0.0"
+    "diff": "^9.0.0",
+    "schemastery": "^3.18.0"
   },
   "peerDependencies": {
     "@deepseek-ai/dsh-fs": "^0.0.1",
diff --git a/packages/fs/tool-fs/src/index.ts b/packages/fs/tool-fs/src/index.ts
index 0aaa0c1a7a..5cc87ba597 100644
--- a/packages/fs/tool-fs/src/index.ts
+++ b/packages/fs/tool-fs/src/index.ts
@@ -23,11 +23,14 @@
  */
 
 import type { Context } from 'cordis'
-import { applyReadTool } from './read.ts'
+import z from 'schemastery'
+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'
 
 export { READ_LIMIT, STREAM_MIN_SIZE, applyReadTool, parseReadArgs } from './read.ts'
+export type { ReadToolCaps } from './read.ts'
 export { applyWriteTool, formatWriteOutput, parseWriteArgs } from './write.ts'
 export { applyEditTool, formatEditOutput, parseEditArgs } from './edit.ts'
 export { READ_MAX_BYTES, READ_MAX_LINE_LENGTH, buildWindow, formatReadOutput } from './read-render.ts'
@@ -41,9 +44,49 @@ export const name = 'tool-fs'
 /** Services required by the filesystem tool suite. */
 export const inject = ['tools', 'fs', 'systemPrompt']
 
+/** Plugin config (all optional — `Config` supplies the defaults). */
+export interface Config {
+  /** Default and maximum number of lines returned by one `read` call. */
+  readLimit?: number
+  /** Maximum characters returned for a single line before truncation. */
+  readMaxLineLength?: number
+  /** Maximum bytes returned for the selected lines of one `read` call. */
+  readMaxBytes?: number
+  /** Files at or above this size stream instead of loading whole into memory. */
+  readStreamMinSize?: number
+}
+
+export const Config: z<Config> = z.object({
+  readLimit: z.number().default(READ_LIMIT),
+  readMaxLineLength: z.number().default(READ_MAX_LINE_LENGTH),
+  readMaxBytes: z.number().default(READ_MAX_BYTES),
+  readStreamMinSize: z.number().default(STREAM_MIN_SIZE),
+})
+
+/** The shape after schemastery applied the defaults. */
+type ResolvedConfig = Required<Config>
+
+/** A read cap must be a positive finite number to bound output and memory. */
+function assertPositiveFinite(name: string, value: number): void {
+  if (!Number.isFinite(value) || value <= 0) {
+    throw new Error(`tool-fs: ${name} must be a positive finite number`)
+  }
+}
+
 /** Register the full `read`/`write`/`edit` filesystem tool suite. */
-export function apply(ctx: Context): void {
-  applyReadTool(ctx)
+export function apply(ctx: Context, config: Config): void {
+  // schemastery (Config) has already filled every defaulted field.
+  const resolved = config as ResolvedConfig
+  assertPositiveFinite('readLimit', resolved.readLimit)
+  assertPositiveFinite('readMaxLineLength', resolved.readMaxLineLength)
+  assertPositiveFinite('readMaxBytes', resolved.readMaxBytes)
+  assertPositiveFinite('readStreamMinSize', resolved.readStreamMinSize)
+  applyReadTool(ctx, {
+    limit: resolved.readLimit,
+    maxLineLength: resolved.readMaxLineLength,
+    maxBytes: resolved.readMaxBytes,
+    streamMinSize: resolved.readStreamMinSize,
+  })
   applyWriteTool(ctx)
   applyEditTool(ctx)
 }
diff --git a/packages/fs/tool-fs/src/read-render.ts b/packages/fs/tool-fs/src/read-render.ts
index 97a1384792..ba0f01f214 100644
--- a/packages/fs/tool-fs/src/read-render.ts
+++ b/packages/fs/tool-fs/src/read-render.ts
@@ -19,21 +19,22 @@
 import { FsError } from '@deepseek-ai/dsh-fs'
 import type { FsVersion } from '@deepseek-ai/dsh-fs'
 
-/** Maximum characters returned for a single line. */
+/** Default maximum characters returned for a single line (the `readMaxLineLength` config). */
 export const READ_MAX_LINE_LENGTH = 2000
 
-/** Maximum bytes returned for selected file lines. */
+/** Default maximum bytes returned for selected file lines (the `readMaxBytes` config). */
 export const READ_MAX_BYTES = 50 * 1024
 
-const READ_MAX_LINE_SUFFIX = `... (line truncated to ${READ_MAX_LINE_LENGTH} chars)`
-const LINE_BUFFER_CAP = READ_MAX_LINE_LENGTH + 1
-
 /** Resolved read window. The consumer applies its defaults/caps before calling. */
 export interface ReadWindow {
   /** 1-based first line to return. */
   offset: number
   /** Maximum number of lines to return. */
   limit: number
+  /** Maximum characters returned for a single line; overflow is truncated with a suffix. */
+  maxLineLength: number
+  /** Maximum bytes of selected output; overflow stops the scan and marks `truncatedByBytes`. */
+  maxBytes: number
 }
 
 /** One line returned from a text file. */
@@ -82,8 +83,8 @@ function newAccumulator(): WindowAccumulator {
   return { lines: [], totalLines: 0, outputBytes: 0, truncatedByBytes: false, done: false }
 }
 
-function truncateLine(line: string): string {
-  return line.length > READ_MAX_LINE_LENGTH ? `${line.substring(0, READ_MAX_LINE_LENGTH)}${READ_MAX_LINE_SUFFIX}` : line
+function truncateLine(line: string, maxLineLength: number): string {
+  return line.length > maxLineLength ? `${line.substring(0, maxLineLength)}... (line truncated to ${maxLineLength} chars)` : line
 }
 
 function lineByteSize(line: string, currentLineCount: number): number {
@@ -94,9 +95,9 @@ function consumeLine(acc: WindowAccumulator, rawLine: string, request: ReadWindo
   acc.totalLines += 1
   if (acc.totalLines < request.offset || acc.lines.length >= request.limit) return
 
-  const text = truncateLine(rawLine)
+  const text = truncateLine(rawLine, request.maxLineLength)
   const bytes = lineByteSize(text, acc.lines.length)
-  if (acc.outputBytes + bytes > READ_MAX_BYTES) {
+  if (acc.outputBytes + bytes > request.maxBytes) {
     acc.truncatedByBytes = true
     acc.done = true
     return
@@ -121,7 +122,7 @@ function finish(acc: WindowAccumulator, request: ReadWindow, displayPath: string
  * Accepts an `AsyncIterable<string>` (a chunked `streamText`) or an
  * `Iterable<string>` (a whole-file `readText` wrapped as `[text]`), so one code
  * path serves both. Scans for newlines with a capped line buffer (a newline-free
- * giant line is truncated, never buffered past {@link READ_MAX_LINE_LENGTH}),
+ * giant line is truncated, never buffered past `request.maxLineLength`),
  * enforces the byte cap, and throws `FS_NOT_FOUND` for an offset past EOF.
  */
 export async function buildWindow(
@@ -130,12 +131,14 @@ export async function buildWindow(
   displayPath: string,
 ): Promise<WindowResult> {
   const acc = newAccumulator()
+  // One char past the truncation point is enough to prove a line overflows.
+  const lineBufferCap = request.maxLineLength + 1
   let lineBuffer = ''
 
   function appendToLineBuffer(segment: string): void {
-    if (lineBuffer.length >= LINE_BUFFER_CAP) return
+    if (lineBuffer.length >= lineBufferCap) return
     lineBuffer += segment
-    if (lineBuffer.length > LINE_BUFFER_CAP) lineBuffer = lineBuffer.slice(0, LINE_BUFFER_CAP)
+    if (lineBuffer.length > lineBufferCap) lineBuffer = lineBuffer.slice(0, lineBufferCap)
   }
 
   function flushLine(): void {
diff --git a/packages/fs/tool-fs/src/read.ts b/packages/fs/tool-fs/src/read.ts
index c984b53c9f..68f21231b2 100644
--- a/packages/fs/tool-fs/src/read.ts
+++ b/packages/fs/tool-fs/src/read.ts
@@ -23,12 +23,27 @@ import { buildWindow, formatReadOutput } from './read-render.ts'
 import type { FileReadOutcome } from './read-render.ts'
 import { sessionCwd } from './session-cwd.ts'
 
-/** Default and maximum number of lines returned by one `read` call. */
+/** Default and maximum number of lines returned by one `read` call (the `readLimit` config). */
 export const READ_LIMIT = 2000
 
-/** Files at or above this size stream; smaller files read whole into memory. */
+/**
+ * Default streaming threshold (the `readStreamMinSize` config): files at or
+ * above this size stream; smaller files read whole into memory.
+ */
 export const STREAM_MIN_SIZE = 10 * 1024 * 1024
 
+/** Resolved read-tool caps — plugin config after defaulting (see `Config` in index.ts). */
+export interface ReadToolCaps {
+  /** Default and maximum number of lines returned by one call. */
+  limit: number
+  /** Maximum characters returned for a single line. */
+  maxLineLength: number
+  /** Maximum bytes returned for selected file lines. */
+  maxBytes: number
+  /** Files at or above this size stream; smaller files read whole into memory. */
+  streamMinSize: number
+}
+
 /** Validated `read` arguments after defaulting. */
 interface ReadInput {
   filePath: string
@@ -43,17 +58,17 @@ function parsePositiveInteger(value: number, name: string): number {
   return value
 }
 
-/** Validate value constraints the schema DSL can't express. */
-export function parseReadArgs(args: { file_path: string; offset?: number; limit?: number }): ReadInput {
+/** Validate value constraints the schema DSL can't express. `maxLimit` is the deployment's line cap. */
+export function parseReadArgs(args: { file_path: string; offset?: number; limit?: number }, maxLimit: number): ReadInput {
   if (args.file_path.trim().length === 0) throw new Error('file_path must be a non-empty string')
   const offset = args.offset === undefined ? 1 : parsePositiveInteger(args.offset, 'offset')
-  const limit = args.limit === undefined ? READ_LIMIT : parsePositiveInteger(args.limit, 'limit')
-  if (limit > READ_LIMIT) throw new Error(`limit must be less than or equal to ${READ_LIMIT}`)
+  const limit = args.limit === undefined ? maxLimit : parsePositiveInteger(args.limit, 'limit')
+  if (limit > maxLimit) throw new Error(`limit must be less than or equal to ${maxLimit}`)
   return { filePath: args.file_path, offset, limit }
 }
 
 /** Register the `read` tool and its system-prompt guidance. */
-export function applyReadTool(ctx: Context): void {
+export function applyReadTool(ctx: Context, caps: ReadToolCaps): void {
   ctx.systemPrompt.section({
     name: 'tool:read',
     order: 100,
@@ -66,10 +81,10 @@ export function applyReadTool(ctx: Context): void {
     parameters: {
       file_path: { type: 'string', required: true, description: 'Path to read, resolved by the filesystem backend.' },
       offset: { type: 'number', description: '1-based first line to return. Defaults to 1.' },
-      limit: { type: 'number', description: `Maximum number of lines to return. Defaults to ${READ_LIMIT}.` },
+      limit: { type: 'number', description: `Maximum number of lines to return. Defaults to ${caps.limit}.` },
     },
     async execute(args, exec): Promise<ContentBlock[]> {
-      const input = parseReadArgs(args)
+      const input = parseReadArgs(args, caps.limit)
       const cwd = sessionCwd(exec)
       const target = await ctx.fs.resolve(input.filePath, cwd !== undefined ? { cwd } : undefined)
 
@@ -83,10 +98,14 @@ export function applyReadTool(ctx: Context): void {
 
       // Stream when the file is large OR size is unknown, so a size-less backend
       // never buffers an arbitrarily large file.
-      const chunks = info.size === undefined || info.size >= STREAM_MIN_SIZE
+      const chunks = info.size === undefined || info.size >= caps.streamMinSize
         ? await ctx.fs.streamText(target, exec.signal)
         : [await ctx.fs.readText(target, exec.signal)]
-      const window = await buildWindow(chunks, { offset: input.offset, limit: input.limit }, target.displayPath)
+      const window = await buildWindow(
+        chunks,
+        { offset: input.offset, limit: input.limit, maxLineLength: caps.maxLineLength, maxBytes: caps.maxBytes },
+        target.displayPath,
+      )
 
       const outcome: FileReadOutcome = {
         offset: input.offset,
@@ -106,7 +125,8 @@ export function applyReadTool(ctx: Context): void {
     // appended (`Read foo.txt (5 - 8)`), `read` kind (icon), and a follow-along
     // location whose line is the read's offset (defaulting to 1). The window is
     // derived from the RAW args (offset/limit as the model passed them), NOT the
-    // tool's defaulted 1/READ_LIMIT, so an unbounded read shows a bare title.
+    // tool's defaulted 1/configured limit, so an unbounded read shows a bare
+    // title (and the presenter stays a pure function of args, config-free).
     presentCall(args): GenericCallView {
       const { offset, limit } = args
       const window = limit !== undefined && limit > 0
diff --git a/packages/fs/tool-fs/tests/read-render.spec.ts b/packages/fs/tool-fs/tests/read-render.spec.ts
index b596a47465..c23ad79170 100644
--- a/packages/fs/tool-fs/tests/read-render.spec.ts
+++ b/packages/fs/tool-fs/tests/read-render.spec.ts
@@ -6,10 +6,11 @@
  */
 
 import { describe, expect, it } from 'vitest'
-import { buildWindow, READ_MAX_LINE_LENGTH } from '@deepseek-ai/dsh-tool-fs'
+import { buildWindow, READ_MAX_BYTES, READ_MAX_LINE_LENGTH } from '@deepseek-ai/dsh-tool-fs'
 import type { ReadWindow } from '@deepseek-ai/dsh-tool-fs'
 
-const READ_ALL: ReadWindow = { offset: 1, limit: 2000 }
+const DEFAULT_CAPS = { maxLineLength: READ_MAX_LINE_LENGTH, maxBytes: READ_MAX_BYTES }
+const READ_ALL: ReadWindow = { offset: 1, limit: 2000, ...DEFAULT_CAPS }
 
 /** Yield `text` as one chunk (whole-file read shape). */
 async function* whole(text: string): AsyncIterable<string> {
@@ -34,7 +35,7 @@ describe('buildWindow', () => {
   })
 
   it('applies offset/limit', async () => {
-    const result = await buildWindow(whole('one\ntwo\nthree\nfour'), { offset: 2, limit: 2 }, 'f')
+    const result = await buildWindow(whole('one\ntwo\nthree\nfour'), { offset: 2, limit: 2, ...DEFAULT_CAPS }, 'f')
     expect(result.lines.map(l => l.number)).toEqual([2, 3])
     expect(result.totalLines).toBe(4)
   })
@@ -62,7 +63,7 @@ describe('buildWindow', () => {
   })
 
   it('rejects an offset past EOF', async () => {
-    await expect(buildWindow(whole('one\ntwo'), { offset: 9, limit: 1 }, 'f')).rejects.toMatchObject({ code: 'FS_NOT_FOUND' })
+    await expect(buildWindow(whole('one\ntwo'), { offset: 9, limit: 1, ...DEFAULT_CAPS }, 'f')).rejects.toMatchObject({ code: 'FS_NOT_FOUND' })
   })
 
   it('flushes a final line with no trailing newline', async () => {
@@ -76,9 +77,22 @@ describe('buildWindow', () => {
     expect(result.totalLines).toBe(2)
   })
 
+  describe('caps are per-request (the plugin config reaches the window)', () => {
+    it('truncates lines at a custom maxLineLength and names it in the suffix', async () => {
+      const result = await buildWindow(whole('abcdefghij'), { offset: 1, limit: 10, maxLineLength: 5, maxBytes: READ_MAX_BYTES }, 'f')
+      expect(result.lines[0]?.text).toBe('abcde... (line truncated to 5 chars)')
+    })
+
+    it('caps output at a custom maxBytes', async () => {
+      const result = await buildWindow(whole('aaaa\nbbbb\ncccc'), { offset: 1, limit: 10, maxLineLength: 2000, maxBytes: 9 }, 'f')
+      expect(result.lines.map(l => l.text)).toEqual(['aaaa', 'bbbb'])
+      expect(result.truncatedByBytes).toBe(true)
+    })
+  })
+
   describe('chunked input (streamed read shape)', () => {
     it('windows identically when text arrives in small chunks', async () => {
-      const result = await buildWindow(chunked('one\ntwo\nthree', 2), { offset: 2, limit: 1 }, 'f')
+      const result = await buildWindow(chunked('one\ntwo\nthree', 2), { offset: 2, limit: 1, ...DEFAULT_CAPS }, 'f')
       expect(result.lines).toEqual([{ number: 2, text: 'two' }])
       expect(result.totalLines).toBe(3)
     })
diff --git a/packages/fs/tool-fs/tests/tools.spec.ts b/packages/fs/tool-fs/tests/tools.spec.ts
index 6272ac5c9d..638ce2112b 100644
--- a/packages/fs/tool-fs/tests/tools.spec.ts
+++ b/packages/fs/tool-fs/tests/tools.spec.ts
@@ -495,3 +495,70 @@ describe('result-time contextual diff (meta + presentResult)', () => {
     expect(view).toEqual({ card: 'diff', title: 'Write a.txt', diffs: [{ path: 'a.txt', oldText: null, newText: 'y' }] })
   })
 })
+
+describe('read caps are plugin config', () => {
+  async function setupWith(config: ToolFs.Config) {
+    const ctx = new Context()
+    await ctx.plugin(SystemPrompt)
+    await ctx.plugin(ToolRegistry)
+    await ctx.plugin(FakeFs)
+    await ctx.plugin(FsPolicy)
+    await ctx.plugin(ToolFs, config)
+    return { ctx, fs: ctx.fs as FakeFs }
+  }
+
+  it('a configured readLimit is both the default and the cap, and the schema names it', async () => {
+    const { ctx, fs } = await setupWith({ readLimit: 2 })
+    fs.files.set('key:a.txt', 'one\ntwo\nthree\nfour')
+    const result = await call(ctx, 'read', { file_path: 'a.txt' })
+    expect(text(result)).toContain('(Showing lines 1-2 of 4. Use offset=3 to continue.)')
+    const overCap = await call(ctx, 'read', { file_path: 'a.txt', limit: 3 })
+    expect(overCap.isError).toBe(true)
+    expect(text(overCap)).toContain('less than or equal to 2')
+    const readSchema = ctx.tools.schemas().find(s => s.name === 'read')
+    expect(JSON.stringify(readSchema)).toContain('Defaults to 2.')
+  })
+
+  it('a configured readMaxLineLength truncates lines at the configured length', async () => {
+    const { ctx, fs } = await setupWith({ readMaxLineLength: 4 })
+    fs.files.set('key:a.txt', 'abcdefgh')
+    const result = await call(ctx, 'read', { file_path: 'a.txt' })
+    expect(text(result)).toContain('1: abcd... (line truncated to 4 chars)')
+  })
+
+  it('a configured readMaxBytes caps the window at the configured bytes', async () => {
+    const { ctx, fs } = await setupWith({ readMaxBytes: 9 })
+    fs.files.set('key:a.txt', 'aaaa\nbbbb\ncccc')
+    const result = await call(ctx, 'read', { file_path: 'a.txt' })
+    expect(text(result)).toContain('Output capped.')
+    expect(text(result)).not.toContain('cccc')
+  })
+
+  it('a configured readStreamMinSize routes smaller files to the streaming path', async () => {
+    const { ctx, fs } = await setupWith({ readStreamMinSize: 5 })
+    fs.files.set('key:a.txt', 'alpha\nbeta')
+    const readSpy = vi.spyOn(fs, 'readText')
+    const streamSpy = vi.spyOn(fs, 'streamText')
+    const result = await call(ctx, 'read', { file_path: 'a.txt' })
+    expect(result.isError).toBe(false)
+    expect(streamSpy).toHaveBeenCalled()
+    expect(readSpy).not.toHaveBeenCalled()
+  })
+
+  it.each([
+    ['readLimit', { readLimit: 0 }],
+    ['readMaxLineLength', { readMaxLineLength: -1 }],
+    ['readMaxBytes', { readMaxBytes: Number.NaN }],
+    ['readStreamMinSize', { readStreamMinSize: 0 }],
+  ] as const)('rejects a non-positive %s at load', async (name, config) => {
+    const ctx = new Context()
+    await ctx.plugin(SystemPrompt)
+    await ctx.plugin(ToolRegistry)
+    await ctx.plugin(FakeFs)
+    await expect(ctx.plugin(ToolFs, config)).rejects.toThrow(new RegExp(`tool-fs: ${name} must be a positive finite number`))
+  })
+
+  it('has no default export (namespace plugin export shape)', () => {
+    expect('default' in ToolFs).toBe(false)
+  })
+})
diff --git a/packages/fs/tool-fs/tsconfig.json b/packages/fs/tool-fs/tsconfig.json
index 6af16400c0..f0133b1d2b 100644
--- a/packages/fs/tool-fs/tsconfig.json
+++ b/packages/fs/tool-fs/tsconfig.json
@@ -8,6 +8,7 @@
   "references": [
     { "path": "../../../vendor/cosmokit" },
     { "path": "../../../vendor/cordis" },
+    { "path": "../../../vendor/schemastery" },
     { "path": "../../llm/llm" },
     { "path": "../../core/tools" },
     { "path": "../../core/system-prompt" },
diff --git a/packages/hooks/hook-protocol/src/events.ts b/packages/hooks/hook-protocol/src/events.ts
index 0db75995c9..d7529b0f45 100644
--- a/packages/hooks/hook-protocol/src/events.ts
+++ b/packages/hooks/hook-protocol/src/events.ts
@@ -58,6 +58,18 @@ export function appendHookInvoked(session: Session, invocation: HookInvocation):
   })
 }
 
+/**
+ * Truncate a hook's stderr for {@link HookResultRecord.stderrSummary}: trimmed,
+ * `undefined` when empty, cut at `maxChars` with an ellipsis when over. The
+ * bound is a parameter — like `runHook`'s `defaultTimeoutMs`, each bridge owns
+ * the config default and passes it in.
+ */
+export function summarizeStderr(stderr: string, maxChars: number): string | undefined {
+  const t = stderr.trim()
+  if (t.length === 0) return undefined
+  return t.length > maxChars ? t.slice(0, maxChars) + '…' : t
+}
+
 /** Append a `hook/result` outcome event to `session` (pairs with a prior `hook/invoked`). */
 export function appendHookResult(session: Session, record: HookResultRecord): void {
   session.append('hook/result', {
diff --git a/packages/hooks/hook-protocol/src/index.ts b/packages/hooks/hook-protocol/src/index.ts
index 686a1480ac..a99fd11b6f 100644
--- a/packages/hooks/hook-protocol/src/index.ts
+++ b/packages/hooks/hook-protocol/src/index.ts
@@ -34,5 +34,5 @@ export { runHook } from './runner.ts'
 export type { RunHookOptions, RunHookResult } from './runner.ts'
 export { mergeHookOutputs } from './merge.ts'
 export type { MergedDecision, MergedHookOutcome } from './merge.ts'
-export { appendHookInvoked, appendHookResult } from './events.ts'
+export { appendHookInvoked, appendHookResult, summarizeStderr } from './events.ts'
 export type { HookInvocation, HookResultRecord } from './events.ts'
diff --git a/packages/hooks/hook-protocol/tests/events.spec.ts b/packages/hooks/hook-protocol/tests/events.spec.ts
index f63ae2a9cb..9f705916b9 100644
--- a/packages/hooks/hook-protocol/tests/events.spec.ts
+++ b/packages/hooks/hook-protocol/tests/events.spec.ts
@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest'
 import { Session, SessionId } from '@deepseek-ai/dsh-session'
-import { appendHookInvoked, appendHookResult } from '@deepseek-ai/dsh-hook-protocol'
+import { appendHookInvoked, appendHookResult, summarizeStderr } from '@deepseek-ai/dsh-hook-protocol'
 
 describe('hook/* session events', () => {
   it('appendHookInvoked records a log-only hook/invoked (with matcher when present)', () => {
@@ -59,3 +59,20 @@ describe('hook/* session events', () => {
     expect(result?.type === 'hook/result' && result.data.handlerId).toBe('pair-1')
   })
 })
+
+describe('summarizeStderr', () => {
+  it('returns undefined for empty/whitespace stderr', () => {
+    expect(summarizeStderr('', 500)).toBeUndefined()
+    expect(summarizeStderr('  \n\t ', 500)).toBeUndefined()
+  })
+
+  it('passes through a summary at or under the cap, trimmed', () => {
+    expect(summarizeStderr('  blocked: bad tool  ', 500)).toBe('blocked: bad tool')
+    expect(summarizeStderr('abc', 3)).toBe('abc')
+  })
+
+  it('truncates past the cap with an ellipsis', () => {
+    expect(summarizeStderr('abcdef', 4)).toBe('abcd…')
+    expect(summarizeStderr('x'.repeat(600), 500)).toBe('x'.repeat(500) + '…')
+  })
+})
diff --git a/packages/hooks/hooks-claude/README.md b/packages/hooks/hooks-claude/README.md
index ce1c6b090a..984a86ba18 100644
--- a/packages/hooks/hooks-claude/README.md
+++ b/packages/hooks/hooks-claude/README.md
@@ -13,6 +13,7 @@ const config: Config = {
   pluginRoot: '/path/to/plugin',     // optional: replaces ${CLAUDE_PLUGIN_ROOT} in command strings
   projectDir: '/path/to/project',    // optional: replaces ${CLAUDE_PROJECT_DIR} AND sets the hook env var; defaults to the session cwd when omitted
   defaultTimeoutMs: 600_000,         // optional: per-hook timeout when a hook sets none (CC default)
+  stderrSummaryMaxChars: 500,        // optional: char cap on the hook/result event's persisted stderr summary
 }
 ```
 
diff --git a/packages/hooks/hooks-claude/src/index.ts b/packages/hooks/hooks-claude/src/index.ts
index 6151a11c44..263b201791 100644
--- a/packages/hooks/hooks-claude/src/index.ts
+++ b/packages/hooks/hooks-claude/src/index.ts
@@ -34,6 +34,7 @@ import {
   matchesMatcher,
   mergeHookOutputs,
   runHook,
+  summarizeStderr,
   type HookOutput,
   type MatcherGroup,
   type MergedHookOutcome,
@@ -73,6 +74,8 @@ export interface Config {
   projectDir?: string
   /** Default per-hook timeout in ms when a hook sets none (CC default: 600000). */
   defaultTimeoutMs?: number
+  /** Character cap for the `hook/result` event's persisted stderr summary. */
+  stderrSummaryMaxChars?: number
 }
 
 export const Config: z<Config> = z.object({
@@ -80,6 +83,7 @@ export const Config: z<Config> = z.object({
   pluginRoot: z.string(),
   projectDir: z.string(),
   defaultTimeoutMs: z.number().default(600_000),
+  stderrSummaryMaxChars: z.number().default(500),
 })
 
 /** A stable per-handler id so an invoked/result pair correlates in the log. */
@@ -91,13 +95,6 @@ function nextHandlerId(point: string): string {
 /** The `{kind:'plugin'}` source stamped on every context this bridge injects. */
 const PLUGIN_SOURCE: MessageSource = { kind: 'plugin', plugin: 'hooks-claude' }
 
-/** Truncate a stderr blob for the `hook/result` summary field. */
-function summarize(stderr: string): string | undefined {
-  const t = stderr.trim()
-  if (t.length === 0) return undefined
-  return t.length > 500 ? t.slice(0, 500) + '…' : t
-}
-
 export function apply(ctx: Context, config: Config): void {
   // --- Parse the config ONCE at load. A read/parse failure is contained: the
   // bridge logs and registers nothing rather than crashing boot (a typo'd path
@@ -119,6 +116,7 @@ export function apply(ctx: Context, config: Config): void {
   }
 
   const defaultTimeoutMs = config.defaultTimeoutMs ?? 600_000
+  const stderrSummaryMaxChars = config.stderrSummaryMaxChars ?? 500
 
   /**
    * Run every command hook configured for `point` whose matcher selects
@@ -182,7 +180,7 @@ export function apply(ctx: Context, config: Config): void {
           ctx.logger.warn(`hooks-claude: ${point} hook emitted a systemMessage, which is not yet surfaced (ignored)`)
         }
         if (session && opts.turn !== undefined) {
-          const stderrSummary = summarize(output.stderr)
+          const stderrSummary = summarizeStderr(output.stderr, stderrSummaryMaxChars)
           appendHookResult(session, {
             turn: opts.turn, point, handlerId,
             decision: output.decision ?? (output.continue === false ? 'stop' : 'pass'),
diff --git a/packages/hooks/hooks-claude/tests/coverage.spec.ts b/packages/hooks/hooks-claude/tests/coverage.spec.ts
index 63e2f611ce..f5091ce7a5 100644
--- a/packages/hooks/hooks-claude/tests/coverage.spec.ts
+++ b/packages/hooks/hooks-claude/tests/coverage.spec.ts
@@ -27,7 +27,7 @@ function hooks(d: string, h: unknown): string {
   writeFileSync(join(d, 'hooks.json'), JSON.stringify({ hooks: h })); return join(d, 'hooks.json')
 }
 
-type HarnessOpts = { pluginRoot?: string; projectDir?: string }
+type HarnessOpts = { pluginRoot?: string; projectDir?: string; stderrSummaryMaxChars?: number }
 async function harness(configPath: string, adapter: MockAdapter, opts: HarnessOpts = {}): Promise<Context> {
   const ctx = new Context()
   await ctx.plugin(LlmService)
@@ -139,6 +139,21 @@ describe('hooks-claude coverage — empty/no-op outcomes and no-agent paths', ()
     await waitForIdle(ctx, agent)
     const res = events(agent).find(e => e.type === 'hook/result')
     expect(res?.type === 'hook/result' && res.data.stderrSummary?.endsWith('…')).toBe(true)
+    expect(res?.type === 'hook/result' && res.data.stderrSummary?.length).toBe(501) // default 500-char cap + ellipsis
+  })
+
+  it('the stderr summary cap is plugin config (stderrSummaryMaxChars)', async () => {
+    const d = dir()
+    const s = sh(d, 'long.sh', '#!/usr/bin/env bash\nprintf "x%.0s" {1..600} >&2\nexit 2\n')
+    const path = hooks(d, { PreToolUse: [{ hooks: [{ type: 'command', command: s }] }] })
+    const adapter = new MockAdapter([toolCallResponse('c1', 'echo', {}), textResponse('done')])
+    const ctx = await harness(path, adapter, { stderrSummaryMaxChars: 40 })
+    ctx.tools.register(defineTool({ name: 'echo', description: 'e', parameters: {}, async execute() { return [{ type: 'text', text: 'ok' }] } }))
+    const agent = ctx.agentLoop.create(AgentId('a1'), { model: 'mock' })
+    agent.send([{ type: 'text', text: 'go' }])
+    await waitForIdle(ctx, agent)
+    const res = events(agent).find(e => e.type === 'hook/result')
+    expect(res?.type === 'hook/result' && res.data.stderrSummary).toBe('x'.repeat(40) + '…')
   })
 })
 
diff --git a/packages/hooks/hooks-codex/README.md b/packages/hooks/hooks-codex/README.md
index 72be33f57f..68de9a49ae 100644
--- a/packages/hooks/hooks-codex/README.md
+++ b/packages/hooks/hooks-codex/README.md
@@ -20,6 +20,7 @@ const config: Config = {
   configPath: '/path/to/.codex/hooks.json', // required
   model: 'deepseek-v4',                      // optional: stamped on every payload (Codex includes `model`)
   defaultTimeoutMs: 600_000,                 // optional: per-hook timeout when a hook sets none
+  stderrSummaryMaxChars: 500,                // optional: char cap on the hook/result event's persisted stderr summary
 }
 ```
 
diff --git a/packages/hooks/hooks-codex/src/index.ts b/packages/hooks/hooks-codex/src/index.ts
index a704a6af24..4f7d6c9ed9 100644
--- a/packages/hooks/hooks-codex/src/index.ts
+++ b/packages/hooks/hooks-codex/src/index.ts
@@ -27,6 +27,7 @@ import {
   matchesMatcher,
   mergeHookOutputs,
   runHook,
+  summarizeStderr,
   type HookOutput,
   type MatcherGroup,
   type MergedHookOutcome,
@@ -49,12 +50,15 @@ export interface Config {
   model?: string
   /** Default per-hook timeout in ms when a hook sets none (Codex default: 600000). */
   defaultTimeoutMs?: number
+  /** Character cap for the `hook/result` event's persisted stderr summary. */
+  stderrSummaryMaxChars?: number
 }
 
 export const Config: z<Config> = z.object({
   configPath: z.string().required(),
   model: z.string().default(''),
   defaultTimeoutMs: z.number().default(600_000),
+  stderrSummaryMaxChars: z.number().default(500),
 })
 
 let handlerCounter = 0
@@ -64,12 +68,6 @@ function nextHandlerId(point: string): string {
 
 const PLUGIN_SOURCE: MessageSource = { kind: 'plugin', plugin: 'hooks-codex' }
 
-function summarize(stderr: string): string | undefined {
-  const t = stderr.trim()
-  if (t.length === 0) return undefined
-  return t.length > 500 ? t.slice(0, 500) + '…' : t
-}
-
 export function apply(ctx: Context, config: Config): void {
   let parsed: CodexHookConfig = {}
   try {
@@ -85,6 +83,7 @@ export function apply(ctx: Context, config: Config): void {
   }
 
   const defaultTimeoutMs = config.defaultTimeoutMs ?? 600_000
+  const stderrSummaryMaxChars = config.stderrSummaryMaxChars ?? 500
   const model = config.model ?? ''
 
   async function runPoint(
@@ -140,7 +139,7 @@ export function apply(ctx: Context, config: Config): void {
           ctx.logger.warn(`hooks-codex: ${point} hook emitted a systemMessage, which is not yet surfaced (ignored)`)
         }
         if (session && opts.turn !== undefined) {
-          const stderrSummary = summarize(output.stderr)
+          const stderrSummary = summarizeStderr(output.stderr, stderrSummaryMaxChars)
           appendHookResult(session, {
             turn: opts.turn, point, handlerId,
             decision: output.decision ?? (output.continue === false ? 'stop' : 'pass'),
diff --git a/packages/hooks/hooks-codex/tests/coverage.spec.ts b/packages/hooks/hooks-codex/tests/coverage.spec.ts
index 87032c98ce..861a2691e1 100644
--- a/packages/hooks/hooks-codex/tests/coverage.spec.ts
+++ b/packages/hooks/hooks-codex/tests/coverage.spec.ts
@@ -23,12 +23,12 @@ function hooks(d: string, h: unknown): string {
   writeFileSync(join(d, 'hooks.json'), JSON.stringify({ hooks: h })); return join(d, 'hooks.json')
 }
 
-async function harness(configPath: string, adapter: MockAdapter): Promise<Context> {
+async function harness(configPath: string, adapter: MockAdapter, opts: { stderrSummaryMaxChars?: number } = {}): Promise<Context> {
   const ctx = new Context()
   await ctx.plugin(LlmService); await ctx.plugin(SessionStore); await ctx.plugin(SystemPrompt)
   await ctx.plugin(ToolRegistry); await ctx.plugin(AgentRegistry); await ctx.plugin(AgentLoop, { agents: [] })
   await ctx.plugin(LocalBashExecutor, { timeoutMs: 10_000 })
-  await ctx.plugin(HooksCodex, { configPath, model: 'm' })
+  await ctx.plugin(HooksCodex, { configPath, model: 'm', ...opts })
   ctx.llm.registerAdapter(['mock'], adapter)
   return ctx
 }
@@ -204,6 +204,19 @@ describe('hooks-codex coverage — decision mapping paths', () => {
     agent.send([{ type: 'text', text: 'go' }]); await waitForIdle(ctx, agent)
     const res = events(agent).find(e => e.type === 'hook/result')
     expect(res?.type === 'hook/result' && res.data.stderrSummary?.endsWith('…')).toBe(true)
+    expect(res?.type === 'hook/result' && res.data.stderrSummary?.length).toBe(501) // default 500-char cap + ellipsis
+  })
+
+  it('the stderr summary cap is plugin config (stderrSummaryMaxChars)', async () => {
+    const d = dir()
+    hooks(d, { PreToolUse: [{ hooks: [{ type: 'command', command: sh(d, 'l.sh', '#!/usr/bin/env bash\nprintf "x%.0s" {1..600} >&2\nexit 2\n') }] }] })
+    const adapter = new MockAdapter([toolCallResponse('c1', 'Bash', { command: 'x' }), textResponse('done')])
+    const ctx = await harness(join(d, 'hooks.json'), adapter, { stderrSummaryMaxChars: 40 })
+    ctx.tools.register(defineTool({ name: 'Bash', description: 'b', parameters: { command: { type: 'string' } }, async execute() { return [{ type: 'text', text: 'ok' }] } }))
+    const agent = ctx.agentLoop.create(AgentId('a1'), { model: 'mock' })
+    agent.send([{ type: 'text', text: 'go' }]); await waitForIdle(ctx, agent)
+    const res = events(agent).find(e => e.type === 'hook/result')
+    expect(res?.type === 'hook/result' && res.data.stderrSummary).toBe('x'.repeat(40) + '…')
   })
 
   it('warns on a skipped async hook and a direct apply() defaults the timeout', async () => {
diff --git a/packages/session-persistence/session-persistence-sqlite/README.md b/packages/session-persistence/session-persistence-sqlite/README.md
index 064cc11fce..d7095633c9 100644
--- a/packages/session-persistence/session-persistence-sqlite/README.md
+++ b/packages/session-persistence/session-persistence-sqlite/README.md
@@ -8,7 +8,7 @@ A SQLite durable session-persistence backend — a second `SessionPersistence` i
 
 Each `SessionEvent` maps 1:1 onto a row in an `events` table `(session_id, seq, type, time, data, source_event_seqs, surface_op)` — `data` is the event payload as JSON text, so the row shape is the event verbatim (including `assistant/chunk`, keeping `seq` contiguous). The two `TEXT` columns `source_event_seqs` and `surface_op` are nullable; they store the event's optional surface-metadata fields (see [session surface](../../../docs/rfc/implemented/architecture/2026-06-18-session-surface.md)). Out-of-log metadata (`SessionHeader`) lives in a `sessions` row. A `sessions` row is written only by the first `append` — its existence is the lazy-materialization signal (`list` reports exactly the sessions that have a row), so no separate column is needed.
 
-The repo targets Node ≥ 24 (the root `engines` field), which includes the stable `node:sqlite` module. The database opens with `foreign_keys = ON` (so `ON DELETE CASCADE` drops a session's events with its row) and `journal_mode = WAL`. The table-layout version is stored in `PRAGMA user_version` and checked on open: a fresh database is stamped with the current `SCHEMA_VERSION`; a database written by any other, incompatible build (a non-current `user_version`, older or newer) is rejected rather than opened against an unknown layout — there is no migration (unreleased software).
+The repo targets Node ≥ 24 (the root `engines` field), which includes the stable `node:sqlite` module. The database opens with `foreign_keys = ON` (so `ON DELETE CASCADE` drops a session's events with its row) and the configured `journal_mode` (default `wal`; pick a rollback-journal mode like `delete` on filesystems where WAL's shared-memory files do not work, e.g. network mounts). The table-layout version is stored in `PRAGMA user_version` and checked on open: a fresh database is stamped with the current `SCHEMA_VERSION`; a database written by any other, incompatible build (a non-current `user_version`, older or newer) is rejected rather than opened against an unknown layout — there is no migration (unreleased software).
 
 ## Contract semantics over rows
 
@@ -21,6 +21,7 @@ The repo targets Node ≥ 24 (the root `engines` field), which includes the stab
 ```ts
 interface Config {
   path: string   // SQLite database file path, or ':memory:' for an in-process DB
+  journalMode?: 'wal' | 'delete' | 'truncate' | 'persist'   // journal_mode pragma; default 'wal'
 }
 ```
 
diff --git a/packages/session-persistence/session-persistence-sqlite/src/index.ts b/packages/session-persistence/session-persistence-sqlite/src/index.ts
index 412c3b58fc..30387b4837 100644
--- a/packages/session-persistence/session-persistence-sqlite/src/index.ts
+++ b/packages/session-persistence/session-persistence-sqlite/src/index.ts
@@ -28,7 +28,7 @@ import {
 } from '@deepseek-ai/dsh-session-persistence'
 import type { Session, SessionEvent, SurfaceEventType, SessionId, SessionHeader } from '@deepseek-ai/dsh-session'
 import {
-  openDatabase, rowToMeta, scanRows, type EventRow, type SessionRow,
+  type JournalMode, openDatabase, rowToMeta, scanRows, type EventRow, type SessionRow,
 } from './schema.ts'
 
 export { SCHEMA_VERSION } from './schema.ts'
@@ -54,6 +54,13 @@ export interface Config {
    * dirs) on construction.
    */
   path: string
+  /**
+   * SQLite `journal_mode` pragma. `wal` (the default) is the recorded
+   * durability model; pick a rollback-journal mode (`delete`/`truncate`/
+   * `persist`) on filesystems where WAL's shared-memory files do not work
+   * (network mounts). See {@link JournalMode}.
+   */
+  journalMode?: JournalMode
 }
 
 /**
@@ -66,6 +73,7 @@ export class SessionPersistenceSqlite extends SessionPersistence implements Pers
 
   static Config: z<Config> = z.object({
     path: z.string().required(),
+    journalMode: z.union(['wal', 'delete', 'truncate', 'persist'] as const).default('wal'),
   })
 
   /**
@@ -83,18 +91,19 @@ export class SessionPersistenceSqlite extends SessionPersistence implements Pers
     super(ctx)
     // Open the database asynchronously (the parent directory may need creating);
     // every hook awaits `ready` first. Opening synchronously would force a sync
-    // mkdir and block plugin apply.
-    this.ready = this.openDb(config.path)
+    // mkdir and block plugin apply. schemastery (static Config) has already
+    // filled `journalMode`; the cast records that runtime fact.
+    this.ready = this.openDb(config.path, (config as Required<Config>).journalMode)
     this.coordinator = new PersistenceCoordinator<number>(this.ctx, this)
   }
 
-  private async openDb(path: string): Promise<void> {
+  private async openDb(path: string, journalMode: JournalMode): Promise<void> {
     if (path !== ':memory:') {
       const abs = resolve(path)
       await mkdir(dirname(abs), { recursive: true, mode: 0o700 })
-      this.db = openDatabase(abs)
+      this.db = openDatabase(abs, journalMode)
     } else {
-      this.db = openDatabase(path)
+      this.db = openDatabase(path, journalMode)
     }
   }
 
diff --git a/packages/session-persistence/session-persistence-sqlite/src/schema.ts b/packages/session-persistence/session-persistence-sqlite/src/schema.ts
index d8db0e087b..2ed6f5853c 100644
--- a/packages/session-persistence/session-persistence-sqlite/src/schema.ts
+++ b/packages/session-persistence/session-persistence-sqlite/src/schema.ts
@@ -45,10 +45,21 @@ export interface EventRow {
   surface_op: string | null
 }
 
+/**
+ * Journal modes the backend will run under. `wal` is the default and the
+ * durability model the persistence ADR records; the rollback-journal modes
+ * (`delete`/`truncate`/`persist`) exist for filesystems where WAL's
+ * shared-memory files do not work (network mounts). `memory`/`off` are
+ * excluded: dropping journal durability silently contradicts what this
+ * backend promises.
+ */
+export type JournalMode = 'wal' | 'delete' | 'truncate' | 'persist'
+
 /**
  * Open the database at `path` and apply the schema + pragmas. `foreign_keys`
- * makes `ON DELETE CASCADE` drop a session's events with its row; `journal_mode
- * = WAL` matches the durability model the ADR records (the row shape maps 1:1
+ * makes `ON DELETE CASCADE` drop a session's events with its row; the
+ * `journal_mode` pragma is set from the plugin's `journalMode` config (`wal`
+ * default — the durability model the ADR records; the row shape maps 1:1
  * onto `SessionEvent`; opencode runs this exact shape on SQLite/WAL).
  *
  * The table-layout version is persisted in SQLite's `PRAGMA user_version` and
@@ -66,10 +77,12 @@ export interface EventRow {
  * makes the version check reject both sibling v3 databases instead of opening
  * one against columns it does not have.
  */
-export function openDatabase(path: string): DatabaseSync {
+export function openDatabase(path: string, journalMode: JournalMode): DatabaseSync {
   const db = new DatabaseSync(path)
   db.exec('PRAGMA foreign_keys = ON')
-  db.exec('PRAGMA journal_mode = WAL')
+  // journalMode is a closed in-code union (validated by the plugin Config), not
+  // user-controlled SQL — safe to interpolate (PRAGMA takes no bound params).
+  db.exec(`PRAGMA journal_mode = ${journalMode.toUpperCase()}`)
   // `PRAGMA user_version` always returns exactly one row { user_version }.
   const { user_version: onDisk } = db.prepare('PRAGMA user_version').get() as { user_version: number }
   if (onDisk !== 0 && onDisk !== SCHEMA_VERSION) {
diff --git a/packages/session-persistence/session-persistence-sqlite/tests/sqlite.spec.ts b/packages/session-persistence/session-persistence-sqlite/tests/sqlite.spec.ts
index 7138718aa5..a6eda72685 100644
--- a/packages/session-persistence/session-persistence-sqlite/tests/sqlite.spec.ts
+++ b/packages/session-persistence/session-persistence-sqlite/tests/sqlite.spec.ts
@@ -1,5 +1,6 @@
 import { afterEach, describe, expect, it } from 'vitest'
 import { Context } from 'cordis'
+import { existsSync } from 'node:fs'
 import { mkdtemp, rm } from 'node:fs/promises'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
@@ -53,7 +54,7 @@ runCoordinatorContract('sqlite', async (): Promise<CoordinatorFixture> => {
       // A row past the committed region whose `data` does not parse: scanRows
       // bounds the preserved prefix at it and returns its seq as tornFrom, which
       // the backend surfaces to the coordinator as the tornMarker to delete from.
-      const db = openDatabase(path)
+      const db = openDatabase(path, 'wal')
       const next = (db.prepare('SELECT COALESCE(MAX(seq), -1) + 1 AS n FROM events WHERE session_id = ?')
         .get(id) as { n: number }).n
       db.prepare('INSERT INTO events (session_id, seq, type, time, data) VALUES (?, ?, ?, ?, ?)')
@@ -192,7 +193,7 @@ describe('SessionPersistenceSqlite: durability and crash semantics', () => {
     await b1.ctx.sessionPersistence.append(m.id, oneTurnLog()) // seqs 0..5
     await b1.dispose()
     // Hand-write an interrupted turn (turn/start seq 6, no turn/end).
-    const db = openDatabase(path)
+    const db = openDatabase(path, 'wal')
     db.prepare('INSERT INTO events (session_id, seq, type, time, data) VALUES (?, 6, ?, 7, ?)')
       .run(m.id, 'turn/start', JSON.stringify({ turn: 2, trigger: { kind: 'message', source: { kind: 'user' } } }))
     db.close()
@@ -204,7 +205,7 @@ describe('SessionPersistenceSqlite: durability and crash semantics', () => {
     expect(loaded.events.at(-1)!.type).toBe('turn/end')
     // load() is mutating: the synthetic turn/end MUST be on disk so the stored log
     // is balanced and the cursor is truthful (contract: load closes, not defers).
-    const probe = openDatabase(path)
+    const probe = openDatabase(path, 'wal')
     const stored = probe.prepare('SELECT seq, type FROM events WHERE session_id = ? ORDER BY seq').all(m.id) as { seq: number; type: string }[]
     probe.close()
     expect(stored.map(r => r.seq)).toEqual([0, 1, 2, 3, 4, 5, 6, 7])
@@ -237,21 +238,21 @@ describe('SessionPersistenceSqlite: durability and crash semantics', () => {
 
   it('rejects opening a database whose schema version is not the current build (newer OR older)', async () => {
     const path = await freshDbPath()
-    openDatabase(path).close() // stamp user_version = SCHEMA_VERSION
+    openDatabase(path, 'wal').close() // stamp user_version = SCHEMA_VERSION
     // Bump user_version past what this build supports.
-    const dbNewer = openDatabase(path)
+    const dbNewer = openDatabase(path, 'wal')
     dbNewer.exec(`PRAGMA user_version = ${SCHEMA_VERSION + 1}`)
     dbNewer.close()
-    expect(() => openDatabase(path)).toThrow(/incompatible with this build/)
+    expect(() => openDatabase(path, 'wal')).toThrow(/incompatible with this build/)
 
     // A stale OLDER version (e.g. a pre-summary-drop v1 DB) is also rejected —
     // we do not migrate (unreleased software, no backward-compat).
     const olderPath = await freshDbPath()
-    openDatabase(olderPath).close()
-    const dbOlder = openDatabase(olderPath)
+    openDatabase(olderPath, 'wal').close()
+    const dbOlder = openDatabase(olderPath, 'wal')
     dbOlder.exec('PRAGMA user_version = 1')
     dbOlder.close()
-    expect(() => openDatabase(olderPath)).toThrow(/incompatible with this build/)
+    expect(() => openDatabase(olderPath, 'wal')).toThrow(/incompatible with this build/)
   })
 
   it('rejects a sibling v3 database (the merge-collided version) rather than opening it against missing columns', async () => {
@@ -261,11 +262,11 @@ describe('SessionPersistenceSqlite: durability and crash semantics', () => {
     // of this build's columns, so it MUST be rejected, not opened. Stamp a v3
     // database and confirm the version check refuses it.
     const path = await freshDbPath()
-    openDatabase(path).close() // creates + stamps user_version = SCHEMA_VERSION (4)
-    const db = openDatabase(path)
+    openDatabase(path, 'wal').close() // creates + stamps user_version = SCHEMA_VERSION (4)
+    const db = openDatabase(path, 'wal')
     db.exec('PRAGMA user_version = 3')
     db.close()
-    expect(() => openDatabase(path)).toThrow(/schema version 3, incompatible with this build/)
+    expect(() => openDatabase(path, 'wal')).toThrow(/schema version 3, incompatible with this build/)
   })
 
   it('a corrupt-JSON row in the uncommitted tail is discarded on load, not unloadable', async () => {
@@ -281,7 +282,7 @@ describe('SessionPersistenceSqlite: durability and crash semantics', () => {
     // unloadable; a torn tail must be discarded. scanRows finds the last
     // turn/end on the seq+type columns (never parsing tail `data`), so the
     // unparsable row after it bounds the preserved prefix and is deleted by load.
-    const db = openDatabase(path)
+    const db = openDatabase(path, 'wal')
     db.prepare('INSERT INTO events (session_id, seq, type, time, data) VALUES (?, 6, ?, 7, ?)')
       .run(m.id, 'turn/start', '{not valid json')
     db.close()
@@ -370,6 +371,29 @@ describe('SessionPersistenceSqlite: edge cases', () => {
     await b2.dispose()
   })
 
+  it('journalMode config reaches the database (default wal, rollback modes selectable)', async () => {
+    // :memory: databases always report journal_mode=memory, so probe file DBs.
+    const walPath = await freshDbPath()
+    const bWal = await backend(walPath)
+    await bWal.ctx.sessionPersistence.create(meta('jm-wal'))
+    expect((openDatabase(walPath, 'wal').prepare('PRAGMA journal_mode').get() as { journal_mode: string }).journal_mode).toBe('wal')
+    await bWal.dispose()
+
+    const deletePath = await freshDbPath()
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    const fiber = await ctx.plugin(SessionPersistenceSqlite, { path: deletePath, journalMode: 'delete' })
+    await ctx.sessionPersistence.create(meta('jm-delete'))
+    // Probe through a second connection: journal_mode=delete is a per-database
+    // property only insofar as no WAL files exist — assert the world, not the
+    // backend's self-report (no -wal sidecar after writes in delete mode).
+    const db = openDatabase(deletePath, 'delete')
+    expect((db.prepare('PRAGMA journal_mode').get() as { journal_mode: string }).journal_mode).toBe('delete')
+    db.close()
+    expect(existsSync(`${deletePath}-wal`)).toBe(false)
+    await fiber.dispose()
+  })
+
   it('HMR: a DIFFERENT session colliding with a materialized on-disk id is rejected', async () => {
     const path = await freshDbPath()
     // Instance 1 materializes a session and disposes.
diff --git a/packages/subagent/subagent-acp/README.md b/packages/subagent/subagent-acp/README.md
index 03990a7369..81bf886067 100644
--- a/packages/subagent/subagent-acp/README.md
+++ b/packages/subagent/subagent-acp/README.md
@@ -25,6 +25,8 @@ Unlike the in-process backends, the child does NOT share this cordis context —
 | `cwd` | string | parent cwd | Working directory for the child process and its ACP session. |
 | `permission` | `'allow' \| 'reject'` | `reject` | How to auto-answer the child's `session/request_permission` prompts. `reject` declines every prompt (answer `cancelled`); `allow` approves via the first allow-shaped option. The first cut surfaces no prompt to a human. |
 | `env` | Record<string,string> | `{}` | Extra env vars for the child (e.g. its own `DEEPSEEK_API_KEY`). Forwarded on top of a credential-scrubbed copy of the parent env, so an explicit key reaches the child while ambient secrets do not leak implicitly. |
+| `disposeEofGraceMs` | number | `6000` | Dispose ladder tier 1: how long the child gets to quiesce on its own after stdin EOF (flush persistence, tear down its nested subprocesses) before SIGTERM. |
+| `disposeGraceMs` | number | `3000` | Dispose ladder tier 2: grace between SIGTERM and the SIGKILL escalation. |
 
 ```yaml
 - id: subagent-acp
diff --git a/packages/subagent/subagent-acp/src/index.ts b/packages/subagent/subagent-acp/src/index.ts
index 037d32889e..cd425e763c 100644
--- a/packages/subagent/subagent-acp/src/index.ts
+++ b/packages/subagent/subagent-acp/src/index.ts
@@ -21,7 +21,7 @@
 import type { Context } from 'cordis'
 import z from 'schemastery'
 import type { SubagentCapabilities, SubagentProvider, SubagentStartRequest } from '@deepseek-ai/dsh-subagent'
-import { type AcpRunSpec, type PermissionPolicy, startAcpRun } from './run.ts'
+import { type AcpRunSpec, DEFAULT_DISPOSE_EOF_GRACE_MS, DEFAULT_DISPOSE_GRACE_MS, type PermissionPolicy, startAcpRun } from './run.ts'
 
 export const name = 'subagent-acp'
 export const inject = ['subagents']
@@ -52,6 +52,14 @@ export interface Config {
    * ambient secrets do not leak implicitly.
    */
   env: Record<string, string>
+  /**
+   * Grace period (ms) for the child's EOF-driven quiesce on dispose — its
+   * window to flush persistence and tear down its own nested subprocesses
+   * before the parent escalates to a signal.
+   */
+  disposeEofGraceMs?: number
+  /** Grace period (ms) between `SIGTERM` and the `SIGKILL` escalation on dispose. */
+  disposeGraceMs?: number
 }
 
 export const Config: z<Config> = z.object({
@@ -61,8 +69,20 @@ export const Config: z<Config> = z.object({
   cwd: z.string(),
   permission: z.union(['allow', 'reject'] as const).default('reject'),
   env: z.dict(z.string()).default({}),
+  disposeEofGraceMs: z.number().default(DEFAULT_DISPOSE_EOF_GRACE_MS),
+  disposeGraceMs: z.number().default(DEFAULT_DISPOSE_GRACE_MS),
 })
 
+/** A dispose grace must be a positive finite number (it bounds the teardown wait). */
+function assertPositiveFinite(name: string, value: number): void {
+  if (!Number.isFinite(value) || value <= 0) {
+    throw new Error(`subagent-acp: ${name} must be a positive finite number`)
+  }
+}
+
+/** The shape after schemastery applied the defaults (cwd has none). */
+type ResolvedConfig = Required<Omit<Config, 'cwd'>> & Pick<Config, 'cwd'>
+
 /**
  * The ACP provider. Advertises NO start-time capabilities: an out-of-process
  * child cannot honor `outputSchema`/`maxDepth`/`toolFilter` (the service rejects
@@ -71,7 +91,7 @@ export const Config: z<Config> = z.object({
 class AcpProvider implements SubagentProvider {
   readonly capabilities: SubagentCapabilities = { outputSchema: false, depthLimit: false, toolFilter: false }
 
-  constructor(readonly name: string, private readonly ctx: Context, private readonly config: Config) {}
+  constructor(readonly name: string, private readonly ctx: Context, private readonly config: ResolvedConfig) {}
 
   start(request: SubagentStartRequest) {
     const spec: AcpRunSpec = {
@@ -80,6 +100,8 @@ class AcpProvider implements SubagentProvider {
       cwd: this.config.cwd ?? process.cwd(),
       permission: this.config.permission,
       env: this.config.env,
+      disposeEofGraceMs: this.config.disposeEofGraceMs,
+      disposeGraceMs: this.config.disposeGraceMs,
       onError: (error, stopReason) => {
         // The seam forbids `result` rejecting, so a child-level failure is
         // flattened to a stop reason — preserve it here rather than losing it.
@@ -91,5 +113,9 @@ class AcpProvider implements SubagentProvider {
 }
 
 export function apply(ctx: Context, config: Config): void {
-  ctx.subagents.registerProvider(new AcpProvider(config.providerName, ctx, config))
+  // schemastery (Config) has already filled every defaulted field.
+  const resolved = config as ResolvedConfig
+  assertPositiveFinite('disposeEofGraceMs', resolved.disposeEofGraceMs)
+  assertPositiveFinite('disposeGraceMs', resolved.disposeGraceMs)
+  ctx.subagents.registerProvider(new AcpProvider(resolved.providerName, ctx, resolved))
 }
diff --git a/packages/subagent/subagent-acp/src/run.ts b/packages/subagent/subagent-acp/src/run.ts
index 06f7a9ece8..74291b7e65 100644
--- a/packages/subagent/subagent-acp/src/run.ts
+++ b/packages/subagent/subagent-acp/src/run.ts
@@ -73,16 +73,16 @@ export interface AcpRunSpec {
   /**
    * Grace period (ms) for the child's EOF-driven quiesce in
    * {@link SubagentRun.dispose} — the window to flush persistence and tear down
-   * its OWN nested subprocesses before the parent escalates to a signal. Defaults
-   * to {@link DEFAULT_DISPOSE_EOF_GRACE_MS}; a test injects a small value.
+   * its OWN nested subprocesses before the parent escalates to a signal. The
+   * plugin fills this from its `disposeEofGraceMs` config.
    */
-  disposeEofGraceMs?: number
+  disposeEofGraceMs: number
   /**
    * Grace period (ms) between `SIGTERM` and the `SIGKILL` escalation in
-   * {@link SubagentRun.dispose}. Defaults to {@link DEFAULT_DISPOSE_GRACE_MS};
-   * a test injects a small value to exercise the escalation without a long wait.
+   * {@link SubagentRun.dispose}. The plugin fills this from its
+   * `disposeGraceMs` config.
    */
-  disposeGraceMs?: number
+  disposeGraceMs: number
   /**
    * Sink for a child-level failure that the run flattened into a stop reason
    * (the seam contract forbids `result` rejecting). The driver calls this with
@@ -94,19 +94,20 @@ export interface AcpRunSpec {
 }
 
 /**
- * Default grace for the child's EOF-driven quiesce on dispose — the window for it
- * to flush persistence and tear down its OWN nested subprocesses (which may run
- * their own `SIGTERM`→`SIGKILL` escalation) before the parent escalates to a
- * signal. Deliberately LARGER than {@link DEFAULT_DISPOSE_GRACE_MS}: a cooperative
- * child whose teardown is itself waiting on a signal-trapping grandchild (e.g. a
- * bash subprocess in its own ~3s SIGTERM→SIGKILL grace) plus a final flush needs
- * MORE than a single signal-grace of headroom, or the parent's SIGTERM cuts it off
- * exactly as it reaches its own SIGKILL+flush. The child is an arbitrary ACP agent,
- * so this is a standalone generous default, NOT derived from any child's internals.
+ * Default grace for the child's EOF-driven quiesce on dispose (the
+ * `disposeEofGraceMs` config) — the window for it to flush persistence and tear
+ * down its OWN nested subprocesses (which may run their own `SIGTERM`→`SIGKILL`
+ * escalation) before the parent escalates to a signal. Deliberately LARGER than
+ * {@link DEFAULT_DISPOSE_GRACE_MS}: a cooperative child whose teardown is itself
+ * waiting on a signal-trapping grandchild (e.g. a bash subprocess in its own ~3s
+ * SIGTERM→SIGKILL grace) plus a final flush needs MORE than a single
+ * signal-grace of headroom, or the parent's SIGTERM cuts it off exactly as it
+ * reaches its own SIGKILL+flush. The child is an arbitrary ACP agent, so this is
+ * a standalone generous default, NOT derived from any child's internals.
  */
 export const DEFAULT_DISPOSE_EOF_GRACE_MS = 6_000
 
-/** Default grace between SIGTERM and SIGKILL on dispose (mirrors the bash executor). */
+/** Default grace between SIGTERM and SIGKILL on dispose (the `disposeGraceMs` config; mirrors the bash executor). */
 export const DEFAULT_DISPOSE_GRACE_MS = 3_000
 
 /**
@@ -372,8 +373,8 @@ export function startAcpRun(request: SubagentStartRequest, spec: AcpRunSpec): Su
       // Reach quiescence, not merely request it (dispose must AWAIT the child
       // actually stopping). If the child is already gone, nothing to do.
       if (child.exitCode !== null || child.signalCode !== null) return
-      const eofGraceMs = spec.disposeEofGraceMs ?? DEFAULT_DISPOSE_EOF_GRACE_MS
-      const graceMs = spec.disposeGraceMs ?? DEFAULT_DISPOSE_GRACE_MS
+      const eofGraceMs = spec.disposeEofGraceMs
+      const graceMs = spec.disposeGraceMs
       // 1. Graceful: end the ACP request stream (stdin EOF) and let the child
       //    quiesce ON ITS OWN. Our acp-agent has NO SIGTERM handler in a normal
       //    session — it tears down via the server bridge's connection-close path
diff --git a/packages/subagent/subagent-acp/tests/subagent-acp.spec.ts b/packages/subagent/subagent-acp/tests/subagent-acp.spec.ts
index 9819320ec5..e1e510d19d 100644
--- a/packages/subagent/subagent-acp/tests/subagent-acp.spec.ts
+++ b/packages/subagent/subagent-acp/tests/subagent-acp.spec.ts
@@ -8,7 +8,7 @@ import { fileURLToPath } from 'node:url'
 import SubagentService from '@deepseek-ai/dsh-subagent'
 import type { Agent } from '@deepseek-ai/dsh-agent'
 import * as acp from '../src/index.ts'
-import { acpStopReason, acpContentText, buildChildEnv, SENSITIVE_ENV_PATTERN, startAcpRun, toAcpPrompt, type AcpRunSpec } from '../src/run.ts'
+import { acpStopReason, acpContentText, buildChildEnv, DEFAULT_DISPOSE_EOF_GRACE_MS, DEFAULT_DISPOSE_GRACE_MS, SENSITIVE_ENV_PATTERN, startAcpRun, toAcpPrompt, type AcpRunSpec } from '../src/run.ts'
 
 /**
  * Keyless integration tests for the ACP subagent backend. Each spawns a REAL
@@ -171,7 +171,7 @@ describe('dsh-subagent-acp', () => {
       const run = startAcpRun(
         { prompt: [{ type: 'text', text: 'p' }], parent: fakeParent, signal: controller.signal },
         // `touch <sentinel>` — runs only if the process is actually spawned.
-        { command: 'touch', args: [sentinel], cwd: tmp, permission: 'reject', env: {} },
+        { command: 'touch', args: [sentinel], cwd: tmp, permission: 'reject', env: {}, disposeEofGraceMs: DEFAULT_DISPOSE_EOF_GRACE_MS, disposeGraceMs: DEFAULT_DISPOSE_GRACE_MS },
       )
       const result = await run.result
       expect(result.stopReason).toBe('aborted')
@@ -390,7 +390,7 @@ describe('dsh-subagent-acp', () => {
     // absent-sink branch).
     const run = startAcpRun(
       { prompt: [{ type: 'text', text: 'p' }], parent: fakeParent },
-      { command: '/nonexistent/acp-agent-binary', args: [], cwd: process.cwd(), permission: 'reject', env: {} },
+      { command: '/nonexistent/acp-agent-binary', args: [], cwd: process.cwd(), permission: 'reject', env: {}, disposeEofGraceMs: DEFAULT_DISPOSE_EOF_GRACE_MS, disposeGraceMs: DEFAULT_DISPOSE_GRACE_MS },
     )
     const result = await run.result
     // The seam contract: a child-level failure resolves error, never rejects.
@@ -398,6 +398,16 @@ describe('dsh-subagent-acp', () => {
     await run.dispose()
   })
 
+  it('rejects a non-positive dispose grace at load', async () => {
+    for (const bad of [{ disposeEofGraceMs: 0 }, { disposeGraceMs: -1 }, { disposeEofGraceMs: Number.NaN }]) {
+      const ctx = new Context()
+      await ctx.plugin(SubagentService)
+      await expect(ctx.plugin(acp, { providerName: 'acp', command: 'true', args: [], permission: 'reject', env: {}, ...bad }))
+        .rejects.toThrow(/subagent-acp: dispose(?:Eof)?GraceMs must be a positive finite number/)
+      await ctx.fiber.dispose()
+    }
+  })
+
   it('resolves error via the provider (real load path) when the command does not exist', async () => {
     const ctx = new Context()
     await ctx.plugin(SubagentService)
@@ -428,6 +438,8 @@ describe('dsh-subagent-acp', () => {
         cwd: process.cwd(),
         permission: 'reject',
         env: {},
+        disposeEofGraceMs: DEFAULT_DISPOSE_EOF_GRACE_MS,
+        disposeGraceMs: DEFAULT_DISPOSE_GRACE_MS,
         onError: (error, stopReason) => { errors.push({ message: error.message, stopReason }) },
       },
     )
diff --git a/packages/web/tool-web/README.md b/packages/web/tool-web/README.md
index f57f38d0d5..e789720cbb 100644
--- a/packages/web/tool-web/README.md
+++ b/packages/web/tool-web/README.md
@@ -17,6 +17,7 @@ Each tool is registered independently; a product that wants only one disables th
 |---|---|---|
 | `search` | `true` | Register `web_search`. |
 | `fetch` | `true` | Register `web_fetch`. |
+| `searchMaxResults` | `8` | Upper bound on sources returned by one `web_search` call (the seam truncates a longer provider list and flags it). |
 
 ```yaml
 - id: tool-web
diff --git a/packages/web/tool-web/src/index.ts b/packages/web/tool-web/src/index.ts
index df8029466a..c0191c023b 100644
--- a/packages/web/tool-web/src/index.ts
+++ b/packages/web/tool-web/src/index.ts
@@ -20,7 +20,7 @@
 import type { Context } from 'cordis'
 import z from 'schemastery'
 import type {} from '@deepseek-ai/dsh-web'
-import { applyWebSearchTool } from './search.ts'
+import { applyWebSearchTool, WEB_SEARCH_MAX_RESULTS } from './search.ts'
 import { applyWebFetchTool } from './fetch.ts'
 
 export { WEB_SEARCH_MAX_RESULTS, applyWebSearchTool, formatSearchOutput, parseSearchArgs, presentSearchCall } from './search.ts'
@@ -38,13 +38,26 @@ export interface Config {
   search?: boolean
   /** Register `web_fetch`. Defaults to true. */
   fetch?: boolean
+  /** Upper bound on sources returned by one `web_search` call. */
+  searchMaxResults?: number
 }
 
 export const Config: z<Config> = z.object({
   search: z.boolean().default(true),
   fetch: z.boolean().default(true),
+  searchMaxResults: z.number().default(WEB_SEARCH_MAX_RESULTS),
 })
 
+/** The shape after schemastery applies its defaults to every field. */
+type ResolvedConfig = Required<Config>
+
+/** The result cap must be a positive integer (it bounds a provider's source list). */
+function assertPositiveInteger(name: string, value: number): void {
+  if (!Number.isInteger(value) || value < 1) {
+    throw new Error(`tool-web: ${name} must be a positive integer`)
+  }
+}
+
 /**
  * Register the enabled web tools. `search`/`fetch` default to true; a product
  * that wants only one disables the other in config. The tools' disposers are
@@ -52,6 +65,9 @@ export const Config: z<Config> = z.object({
  * teardown is needed.
  */
 export function apply(ctx: Context, config: Config): void {
-  if (config.search !== false) applyWebSearchTool(ctx)
-  if (config.fetch !== false) applyWebFetchTool(ctx)
+  // schemastery (Config) has already filled every defaulted field.
+  const resolved = config as ResolvedConfig
+  assertPositiveInteger('searchMaxResults', resolved.searchMaxResults)
+  if (resolved.search) applyWebSearchTool(ctx, resolved.searchMaxResults)
+  if (resolved.fetch) applyWebFetchTool(ctx)
 }
diff --git a/packages/web/tool-web/src/search.ts b/packages/web/tool-web/src/search.ts
index 6394d3f7e0..28e4e9a2e9 100644
--- a/packages/web/tool-web/src/search.ts
+++ b/packages/web/tool-web/src/search.ts
@@ -13,10 +13,10 @@ import type { WebSearchResult } from '@deepseek-ai/dsh-web'
 import type {} from '@deepseek-ai/dsh-system-prompt'
 
 /**
- * Default upper bound on returned sources. Owned by the consumer (not the
- * provider or model), mirroring `dsh-tool-fs`'s `READ_LIMIT`/`GREP_LIMIT`. The
- * model just asks a question; the product controls how much context returns.
- * The default `8` aligns with OpenCode's Exa default.
+ * Default upper bound on returned sources (the `searchMaxResults` config).
+ * Owned by the consumer (not the provider or model), mirroring `dsh-tool-fs`'s
+ * `READ_LIMIT`. The model just asks a question; the product controls how much
+ * context returns. The default `8` aligns with OpenCode's Exa default.
  */
 export const WEB_SEARCH_MAX_RESULTS = 8
 
@@ -67,8 +67,8 @@ export function presentSearchCall(args: { query: string }): GenericCallView {
   return { card: 'generic', title: args.query, kind: 'search', rawInput: args.query }
 }
 
-/** Register the `web_search` tool and its system-prompt guidance. */
-export function applyWebSearchTool(ctx: Context): void {
+/** Register the `web_search` tool and its system-prompt guidance. `maxResults` is the deployment's source cap. */
+export function applyWebSearchTool(ctx: Context, maxResults: number): void {
   ctx.systemPrompt.section({
     name: 'tool:web_search',
     order: 110,
@@ -84,7 +84,7 @@ export function applyWebSearchTool(ctx: Context): void {
     async execute(args, exec): Promise<ContentBlock[]> {
       const input = parseSearchArgs(args)
       const result = await ctx.web.search(
-        { query: input.query, maxResults: WEB_SEARCH_MAX_RESULTS },
+        { query: input.query, maxResults },
         exec.signal ? { signal: exec.signal } : undefined,
       )
       return [{ type: 'text', text: formatSearchOutput(result) }]
diff --git a/packages/web/tool-web/tests/tool-web.spec.ts b/packages/web/tool-web/tests/tool-web.spec.ts
index 7af1ce7c36..c253bebfef 100644
--- a/packages/web/tool-web/tests/tool-web.spec.ts
+++ b/packages/web/tool-web/tests/tool-web.spec.ts
@@ -15,6 +15,7 @@ import {
   presentFetchCall,
   renderBody,
   htmlToMarkdown,
+  WEB_SEARCH_MAX_RESULTS,
 } from '@deepseek-ai/dsh-tool-web'
 
 const available: WebProviderStatus = { available: true }
@@ -279,3 +280,48 @@ describe('tool-web execution through the real registry', () => {
     await fiber.dispose()
   })
 })
+
+describe('searchMaxResults is plugin config', () => {
+  it('forwards the default cap to the seam when unconfigured', async () => {
+    const seen: { maxResults?: number | undefined } = {}
+    const provider: WebSearchProvider = {
+      id: 'stub-search',
+      status: () => available,
+      search: (request) => { seen.maxResults = request.maxResults; return Promise.resolve({ providerId: 'stub-search', query: 'q', sources: [], truncated: false }) },
+    }
+    const { fiber, call } = await mountTools({ webConfig: { searchProvider: 'stub-search' }, search: provider })
+    await call('web_search', { query: 'q' })
+    expect(seen.maxResults).toBe(WEB_SEARCH_MAX_RESULTS)
+    await fiber.dispose()
+  })
+
+  it('forwards a configured cap to the seam, which enforces it', async () => {
+    const sources = Array.from({ length: 5 }, (_, i) => ({ url: `https://s${i}.test` }))
+    const provider: WebSearchProvider = {
+      id: 'stub-search',
+      status: () => available,
+      search: request => Promise.resolve({ providerId: 'stub-search', query: request.query, sources, truncated: false }),
+    }
+    const { fiber, call } = await mountTools({ config: { searchMaxResults: 2 }, webConfig: { searchProvider: 'stub-search' }, search: provider })
+    const out = await call('web_search', { query: 'q' })
+    expect(out.isError).toBe(false)
+    const body = out.content.map(b => b.text).join('')
+    expect(body).toContain('https://s1.test')
+    expect(body).not.toContain('https://s2.test')
+    expect(body).toContain('Showing the first 2 sources.')
+    await fiber.dispose()
+  })
+
+  it.each([
+    ['zero', 0],
+    ['negative', -3],
+    ['fractional', 1.5],
+  ])('rejects a %s searchMaxResults at load', async (_label, value) => {
+    const ctx = new Context()
+    await ctx.plugin(SystemPrompt)
+    await ctx.plugin(ToolRegistry)
+    await ctx.plugin(WebService, {})
+    await expect(ctx.plugin(ToolWeb, { searchMaxResults: value }))
+      .rejects.toThrow(/tool-web: searchMaxResults must be a positive integer/)
+  })
+})
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 8045aa9cc3..a58d9cb72d 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -323,6 +323,9 @@ importers:
       diff:
         specifier: ^9.0.0
         version: 9.0.0
+      schemastery:
+        specifier: ^3.18.0
+        version: 3.18.0
     devDependencies:
       '@deepseek-ai/dsh-agent':
         specifier: workspace:^