Merge pull request #156 from deepseek-harness/worktree-plugin-config-guideline

No hardcoded tunables in plugins: convention, review check, audit + fixes
2026-08-15 21:04:50 +00:00 · 2026-07-04 20:43:54 +08:00
parent 6c7bbe0e6a 0c5eadf9de
commit c2c13529cd
51 changed files with 672 additions and 176 deletions
--- a/.agents/skills/dsh-code-review/SKILL.md
+++ b/.agents/skills/dsh-code-review/SKILL.md
@@ -21,7 +21,7 @@ Independent judgment governs *what to look at* and *how to apply a rule to this

 These define the conventions and gates this repo is checked against, and they are authoritative. Read them at the source so this skill never drifts out of sync — and apply judgment in *interpreting* them for the case at hand, not in deciding whether they apply.

- **[AGENTS.md](../../../AGENTS.md) § Conventions** — effect-based registrations, declaration-merging for events/ctx keys, waterfall `next()` discipline, discriminated-union match-don't-chain, explicit-over-implicit at seams, the empty-`catch` rule, symmetry.
+- **[AGENTS.md](../../../AGENTS.md) § Conventions** — effect-based registrations, declaration-merging for events/ctx keys, waterfall `next()` discipline, discriminated-union match-don't-chain, explicit-over-implicit at seams, no hardcoded tunables in plugins, the empty-`catch` rule, symmetry.
 - **[docs/defensive-patterns.md](../../../docs/defensive-patterns.md)** — each section is a bug class that bit us. Reviewing anything touching process lifecycle, async/await, disposal, or adapter error paths? Re-read this first — then look for the *adjacent* mistake it doesn't name.
 - **AGENTS.md § Type safety and documentation + [docs/AGENTS.md](../../../docs/AGENTS.md)** — the doc-sync rule (code change ⇒ update README + JSDoc in the SAME commit) and the writing rules (current-state-never-history, one line per paragraph, one home per fact, the word-budget gate).
 - **[packages/AGENTS.md](../../../packages/AGENTS.md)** — per-package conventions (file layout, the HMR-safety test requirement).
@@ -44,6 +44,7 @@ Where your independent reasoning earns its keep. Start here, then keep going acr
 - **e2e verifies the world, not the agent's self-report.** For real-API tests, confirm the assertion re-runs the command/checks the file externally — a keyword probe lets a cheating agent pass. For a behavior change to the agent's real flows, a no-key/mock test alone is usually insufficient: a with-key e2e (especially a smoke test that boots the real example and checks the world) is cheap here and catches "green units, broken product" — encourage it rather than treating real-API tests as expensive (see [docs/testing.md](../../../docs/testing.md)).
 - **Plugin export shape + real-loader coverage.** A new/changed `cordis.yml`-loaded plugin: is it a function/namespace plugin (`name`/`inject`/`Config`/`apply` named exports) with NO `export default`? A stray default export makes the Loader's `unwrapExports` drop `inject` and the plugin crashes at load with `cannot get property … without inject` — invisible to hand-built `ctx.plugin({...})` tests and to line coverage. Confirm there's a test driving it through the REAL loader path (the no-key subprocess e2e for ACP is the model). And any opportunistic read of a service NOT in `static inject` should use `ctx.get(name)`, not `ctx.<name>` (the property proxy throws through a foreign shadow). See [packages/AGENTS.md](../../../packages/AGENTS.md) and [docs/postmortem/0001](../../../docs/postmortem/0001-acp-default-export-drops-inject.md).
 - **Seam discipline.** New swappable capability? Check it's split per the capability-seams RFC (interface / impl / consumer), and that the consumer injects the interface key, never an implementation type.
+- **Hardcoded tunables that should be plugin config.** A literal timeout, grace period, output/truncation cap, result-count limit, retry count, buffer size, model name, API base URL, user agent, or filesystem path introduced inside a plugin belongs on the plugin's schemastery `Config` with the shipped value as its default (AGENTS.md § Conventions "No hardcoded tunables in plugins"). A named `DEFAULT_*` constant or a test-only injection seam is not configurability — the question to ask is whether a `cordis.yml` deployment can change the value without a code edit. Protocol/wire constants, semantic constants, values pinned by an external spec, and security invariants are exempt; a new `Config` field also needs its README row and range validation. No gate detects a hardcoded tunable — this check is entirely on the reviewer.
 - **Test quality — sufficiency, not just coverage.** 100% per-file coverage and a green suite are necessary, not sufficient: they prove the lines *ran*, not that the feature *works the way it ships*. Judge whether the tests are sufficient on two axes. (1) **Would they fail if the behavior regressed?** A test that passes but asserts the wrong thing — or restates the implementation instead of the contract (events fired, disposal reached, the world changed) — is worse than none. (2) **Do they exercise the REAL thing, the way it's actually used?** Prefer the genuine collaborator over a fake, drive the change through its real entry path (the cordis Loader, the ACP bridge, a booted subprocess — not a hand-built `ctx.plugin({...})` that bypasses `unwrapExports`), and verify the WORLD (re-read the file/log/registry externally), not the agent's self-report. A test that fakes the inputs just enough to cover every line will agree with whatever the author assumed; the real thing won't. When a test sets up a *clean/happy* path to reach a line, ask whether the line's PURPOSE is exercised — e.g. a durability/teardown path "tested" by a fully-completed turn never proves the mid-flight teardown it exists for; a torn-tail recovery branch covered by a well-formed log never proves recovery. Flag tests that hit the line but not the scenario. See [docs/testing.md](../../../docs/testing.md) § "Test the real entry path" and § "Prefer the real implementation over a mock".
 - **Snapshot coverage for transcript/UX changes.** If the PR changes the editor-facing transcript or end-to-end agent UX — the ACP bridge's event→update translation, the agent loop's observable output, tool presentation, or anything an editor renders — it must add or update a snapshot scenario (`examples/*/tests/**/*.snapshot.ts`, goldens under `examples/acp-agent/tests/snapshots/`) or note explicitly why none applies (AGENTS.md § Conventions). Review the golden diff itself: a changed `stdout.golden.txt` / `session.golden.txt` is a behavior change in disguise — confirm it's intended, not an accidental regression someone re-recorded away. A pure internal refactor with no observable-output change is exempt, but the PR should say so. See [docs/rfc/implemented/testing/2026-06-19-acp-snapshot-tests.md](../../../docs/rfc/implemented/testing/2026-06-19-acp-snapshot-tests.md).
 - **Bilingual docs: review translation quality, not just pairing.** If the PR adds or edits a doc pair, read the changed English and Chinese sides and compare the meaning, not only the mechanical diff. Verify terms against [terminology.md](../../../docs/i18n/terminology.md), including first-occurrence annotations and "do not translate as" prohibitions; if a new term has no established precedent, the PR should keep it in English, list it under `待定术语`, and update the terminology table once the rendering is decided. A green `verify-translation-pairing` only proves hashes, switchers, and structure were recorded — it does not prove the translation is faithful, natural, or correctly termed. Treat [translation-rules.md](../../../docs/i18n/translation-rules.md) MUST/MUST NOT violations as blocking.
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -89,6 +89,7 @@ Real-API tests and demos read `DEEPSEEK_API_KEY` (and optional `DEEPSEEK_BASE_UR
 - **Plugins, not loop changes**: new behavior goes on the documented extension seams; changing `agent-loop` requires updating docs/architecture.md.
 - **Capability seams are three packages** — interface / implementation / consumer ([capability seams](docs/rfc/implemented/architecture/2026-06-13-capability-seams.md)); don't split preemptively.
 - **Explicit > implicit at package seams**: no optional field silently filled by a hidden `?? default` inside `run()`; defaulting is an explicit `resolve(request): Spec` step in the owning implementation (the `dsh-bash` request/spec split is the template).
+- **No hardcoded tunables in plugins**: anything two deployments could want different — timeouts, caps, grace periods, model names, base URLs — is a defaulted, validated `Config` field, not a literal; a `DEFAULT_*` constant or test-only seam is not configurability. The test: changeable from `cordis.yml`, no code edit. Protocol/wire constants, external-spec values, security invariants stay hardcoded.
 - **Opaque cross-boundary ids are branded** (`Branded<B>` from `dsh-brand`), never bare `string` ([branded IDs](docs/rfc/implemented/architecture/2026-06-20-branded-ids.md)).
 - **An empty `catch` names what it swallows** and why nothing else can reach it; keep the `try` to one statement.
 - **Symmetry is usually more correct**: parallel values get parallel form; asymmetry is a smell for a missed extraction.
--- 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 {
--- 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:

--- a/docs/rfc/implemented/feature/2026-06-18-compaction-capability-seam.md
+++ b/docs/rfc/implemented/feature/2026-06-18-compaction-capability-seam.md
@@ -17,7 +17,7 @@ Two forces shape the design. First, compaction is **swappable**: token counting
 Per the [capability-seams RFC](../../implemented/architecture/2026-06-13-capability-seams.md), compaction ships as separate packages so the contract, the algorithm, and (later) the consumer surface evolve independently:

 1. **Interface** — `@deepseek-ai/dsh-compact`: an abstract `CompactService` owning the `ctx.compact` key, the `CompactionResult` vocabulary, and the `compact/*` session events. It declares `compactIfNeeded()` and `compactRegion()` as **abstract** — the contract states *what* compaction does, not *how*.
-2. **Implementation** — `@deepseek-ai/dsh-compact-basic`: a concrete `BasicCompactService` that owns the entire algorithm — token estimation (char/4 + per-block overhead), the tail→head retention walk, summarization via `ctx.llm.stream()`, the surface replacement, the lock, and the `agent/pre-step` auto-compaction listener. A tokenizer-based or template-based backend is a sibling package (or a subclass overriding the two protected estimation/summarization hooks).
+2. **Implementation** — `@deepseek-ai/dsh-compact-basic`: a concrete `BasicCompactService` that owns the entire algorithm — token estimation (chars per token — the `charsPerToken` config, default 4 — + per-block overhead), the tail→head retention walk, summarization via `ctx.llm.stream()`, the surface replacement, the lock, and the `agent/pre-step` auto-compaction listener. A tokenizer-based or template-based backend is a sibling package (or a subclass overriding the two protected estimation/summarization hooks).
 3. **Consumer** — deferred. A `/compact` tool and slash command will `inject: ['compact']` and call the contract; they are intentionally out of scope here so the seam settles first.

 ### The contract depends on `dsh-session` and `dsh-llm` — a deliberate deviation
--- 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.
--- 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.
--- 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,
--- 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) {
--- 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))
--- 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
--- 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')
--- a/packages/compact/README.md
+++ b/packages/compact/README.md
@@ -5,7 +5,7 @@ A three-package capability seam (see [capability seams](../../docs/rfc/implement
 | Package | Role | ctx key |
 |---|---|---|
 | `compact/` | Abstract compaction seam (interface + `compact/*` events + `CompactionResult`) | `ctx.compact` |
-| `compact-basic/` | A backend: char/4 estimation + token-budget retention + `llm.stream()` summarization | (registers `ctx.compact`) |
+| `compact-basic/` | A backend: chars-per-token estimation (`charsPerToken`, default 4) + token-budget retention + `llm.stream()` summarization | (registers `ctx.compact`) |
 | `tool-compact/` (deferred) | Model-facing `/compact` tool over `ctx.compact` | (registers on `ctx.tools`) |

 The interface lives at `compact/compact/`, the backend at `compact/compact-basic/`. Unlike the bash seam, it depends on `dsh-session` and `dsh-llm` — its verbs are defined over a `Session` and its output is the `ContentBlock` vocabulary, so the contract cannot be expressed without naming them. That deviation from the "interface depends only on cordis" guidance is intentional and recorded in the [compaction capability-seam RFC](../../docs/rfc/implemented/feature/2026-06-18-compaction-capability-seam.md). A tokenizer- or template-based backend would replace `compact-basic` without touching the interface or the tool.
--- a/packages/compact/compact-basic/README.md
+++ b/packages/compact/compact-basic/README.md
@@ -1,6 +1,6 @@
 # @deepseek-ai/dsh-compact-basic

-The **basic compaction backend**: a `BasicCompactService` implementing the `@deepseek-ai/dsh-compact` seam with a char/4 token heuristic, token-budget retention, and summarization routed through the agent request pipeline.
+The **basic compaction backend**: a `BasicCompactService` implementing the `@deepseek-ai/dsh-compact` seam with a chars-per-token heuristic (the `charsPerToken` config, default 4), token-budget retention, and summarization routed through the agent request pipeline.

 This is the implementation tier of the compaction capability — see the [interface package](../compact/README.md) for the seam and the [capability-seam RFC](../../../docs/rfc/implemented/feature/2026-06-18-compaction-capability-seam.md) for the design.

@@ -8,7 +8,7 @@ This is the implementation tier of the compaction capability — see the [interf

 The abstract contract states only WHAT compaction does; this backend owns every HOW decision:

- **Token estimation** — `estimateContentTokens()`: char/4 with per-block structural overhead (`text`/`reasoning` = `ceil(len/4) + 4`, `tool-call` from name + arguments, `tool-result` recursive, `image` = 85, unknown blocks via JSON length).
+- **Token estimation** — `estimateContentTokens()`: chars divided by the `charsPerToken` config (default 4) with per-block structural overhead (`text`/`reasoning` = `ceil(len/charsPerToken) + 4`, `tool-call` from name + arguments, `tool-result` recursive, `image` = 85, unknown blocks via JSON length).
 - **Retention policy** — `compactIfNeeded()` walks the surface nodes tail→head summing per-node token estimates, and retains the smallest tail-run of WHOLE units (a closed step, or a single no-step node such as a pre-step `user/message` or inter-step `steering/message`) whose total reaches `retainTokens`; everything older is compacted. Retention is **turn-agnostic** — turn boundaries play no role, so a single runaway turn that alone exceeds the window compacts its OWN early closed steps rather than being retained verbatim (the failure mode that motivated dropping turn-protection: a tool-heavy turn must stay compactable or the harness dies exactly when compaction is needed). The only structural guard is **tool-pairing balance**: the compacted region's edges are balanced cuts on the surface (no unanswered tool-call crosses either edge), so it never splits a step's `assistant/message` tool-calls from their `tool/result`s. When the only compactable content left is an un-splittable open tail step, it declines (returns `null`) and retries once an older step closes. **Single-unit overflow is out of scope, by design**: if one retained unit (a single closed step, or a large pasted `user/message`) ALONE exceeds the budget, compaction cannot help and the call may go out over-budget — bounding an individual unit's size is a separate concern. `compactRegion()` enforces tool-pairing balance strictly, throwing on a boundary that would split a step. `dsh-session` exports `isToolPairingBalanced` for the check.
 - **Dynamic convergence** — no static summary-length config pretends to bound what the model will write. If framing/estimator/system overhead leaves the compacted surface above threshold, `compactIfNeeded()` re-compacts the head checkpoint up to `compactionRetries` extra times; if it still cannot get below threshold, it throws. A summary whose estimated stored size is not smaller than the shadowed content fails closed before it mutates the surface.
 - **Summarization** — `summarize()`: a `GenerateOptions` request assembled via `BlockAssembler` with a fixed system prompt that asks for a structured checkpoint (Primary Request and Intent · Key Technical Concepts · Files and Code · Errors and Fixes · Pending Tasks · Current Work · Next Step · Critical Context), every section mandatory, exact paths/commands/identifiers preserved. The request runs through the `agent/request` waterfall before `ctx.llm.stream()`, so router agents that choose the concrete model there also route compaction summaries. `maxTokens` is the provider-side generation cap; only text blocks from the model's reply are kept before the checkpoint is stored (reasoning is dropped so private chain-of-thought never leaks into the durable summary, and a stray `tool-call` is dropped so the synthesized `user/message` summary cannot land an orphaned call with no matching `tool-result`). The compacted region is flattened to a plain-text transcript first: text and reasoning contribute their text, and every non-text block (image, tool-call, tool-result, plugin-added types) contributes a type-tagged placeholder (`[image]`, `[tool-call: name(args)]`, …) so the summarizer is told what existed rather than silently dropping it.
@@ -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

--- a/packages/compact/compact-basic/package.json
+++ b/packages/compact/compact-basic/package.json
@@ -1,6 +1,6 @@
 {
  "name": "@deepseek-ai/dsh-compact-basic",
-  "description": "Basic compaction backend (char/4 token estimation + token-budget retention + llm.generate() summarization) for the DeepSeek Harness",
+  "description": "Basic compaction backend (chars-per-token estimation + token-budget retention + llm.generate() summarization) for the DeepSeek Harness",
  "version": "0.0.1",
  "private": true,
  "type": "module",
--- a/packages/compact/compact-basic/src/index.ts
+++ b/packages/compact/compact-basic/src/index.ts
@@ -2,7 +2,8 @@
 * `BasicCompactService`: the first implementation of the
 * `@deepseek-ai/dsh-compact` seam. It owns the entire compaction strategy:
 *
- * - **Token estimation** — char/4 heuristic with per-block structural overhead.
+ * - **Token estimation** — chars/`charsPerToken` heuristic (config, default 4)
+ *   with per-block structural overhead.
 * - **Retention policy** — walk surface nodes tail→head, keep recent nodes up
 *   to a token budget, compact everything older. The cutoff is snapped forward
 *   to the next balanced tool-pairing boundary so a compacted region never
@@ -148,9 +149,11 @@ 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 +210,27 @@ 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 +242,7 @@ 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 +272,7 @@ 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
  }

--- 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].`)
--- 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', () => {
--- a/packages/compact/compact/README.md
+++ b/packages/compact/compact/README.md
@@ -7,7 +7,7 @@ This package is the interface tier of the compaction capability, split so each c
 | Package | Role |
 |---|---|
 | `@deepseek-ai/dsh-compact` (this) | the interface: abstract service + `compact/*` events + `CompactionResult` |
-| `@deepseek-ai/dsh-compact-basic` (deferred) | a backend: char/4 estimation + token-budget retention + `llm.stream()` summarization |
+| `@deepseek-ai/dsh-compact-basic` (deferred) | a backend: chars-per-token estimation (`charsPerToken`, default 4) + token-budget retention + `llm.stream()` summarization |
 | `@deepseek-ai/dsh-tool-compact` (deferred) | the model-facing `/compact` tool over `ctx.compact` |

 Unlike the bash seam, this interface depends on `@deepseek-ai/dsh-session` and `@deepseek-ai/dsh-llm` — the contract's verbs are defined over a `Session` and its output is the `ContentBlock` vocabulary, so they cannot be expressed without naming those packages. That deviation from the "interface depends only on cordis" guidance is intentional and recorded in the [compaction capability-seam RFC](../../../docs/rfc/implemented/feature/2026-06-18-compaction-capability-seam.md).
--- 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). */
--- 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,
--- 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. |

--- 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",
--- 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>
+
+/** Every read cap counts lines/chars/bytes — a positive integer, or windowing arithmetic misbehaves silently. */
+function assertPositiveInteger(name: string, value: number): void {
+  if (!Number.isInteger(value) || value < 1) {
+    throw new Error(`tool-fs: ${name} must be a positive integer`)
+  }
+}
+
 /** 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
+  assertPositiveInteger('readLimit', resolved.readLimit)
+  assertPositiveInteger('readMaxLineLength', resolved.readMaxLineLength)
+  assertPositiveInteger('readMaxBytes', resolved.readMaxBytes)
+  assertPositiveInteger('readStreamMinSize', resolved.readStreamMinSize)
+  applyReadTool(ctx, {
+    limit: resolved.readLimit,
+    maxLineLength: resolved.readMaxLineLength,
+    maxBytes: resolved.readMaxBytes,
+    streamMinSize: resolved.readStreamMinSize,
+  })
  applyWriteTool(ctx)
  applyEditTool(ctx)
 }
--- 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 {
--- 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
--- 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)
    })
--- a/packages/fs/tool-fs/tests/tools.spec.ts
+++ b/packages/fs/tool-fs/tests/tools.spec.ts
@@ -495,3 +495,71 @@ 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 }],
+    ['readLimit', { readLimit: 2.5 }],
+    ['readMaxLineLength', { readMaxLineLength: -1 }],
+    ['readMaxBytes', { readMaxBytes: Number.NaN }],
+    ['readStreamMinSize', { readStreamMinSize: 0 }],
+  ] as const)('rejects a non-positive or fractional %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 integer`))
+  })
+
+  it('has no default export (namespace plugin export shape)', () => {
+    expect('default' in ToolFs).toBe(false)
+  })
+})
--- 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" },
--- 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', {
--- 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'
--- 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) + '…')
+  })
+})
--- 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
 }
 ```

--- 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. */
@@ -91,14 +95,18 @@ 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
+/** The summary cap bounds a persisted event field — a positive integer or the slice misbehaves silently. */
+function assertPositiveInteger(name: string, value: number): void {
+  if (!Number.isInteger(value) || value < 1) {
+    throw new Error(`hooks-claude: ${name} must be a positive integer`)
+  }
 }

 export function apply(ctx: Context, config: Config): void {
+  // Validate the cap BEFORE the config-file parse: a bad value must fail the
+  // load loudly, not be skipped by the parse-failure early return.
+  const stderrSummaryMaxChars = config.stderrSummaryMaxChars ?? 500
+  assertPositiveInteger('stderrSummaryMaxChars', stderrSummaryMaxChars)
  // --- 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
  // must not take the agent down). ---
@@ -182,7 +190,7 @@ 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'),
--- 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 +139,31 @@ 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('rejects a non-positive or fractional stderrSummaryMaxChars at load', async () => {
+    const d = dir()
+    const path = hooks(d, {})
+    for (const bad of [0, -5, 1.5, Number.NaN]) {
+      const adapter = new MockAdapter([])
+      await expect(harness(path, adapter, { stderrSummaryMaxChars: bad }))
+        .rejects.toThrow(/hooks-claude: stderrSummaryMaxChars must be a positive integer/)
+    }
+  })
+
+  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) + '…')
  })
 })

--- 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
 }
 ```

--- 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
@@ -64,13 +68,18 @@ 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
+/** The summary cap bounds a persisted event field — a positive integer or the slice misbehaves silently. */
+function assertPositiveInteger(name: string, value: number): void {
+  if (!Number.isInteger(value) || value < 1) {
+    throw new Error(`hooks-codex: ${name} must be a positive integer`)
+  }
 }

 export function apply(ctx: Context, config: Config): void {
+  // Validate the cap BEFORE the config-file parse: a bad value must fail the
+  // load loudly, not be skipped by the parse-failure early return.
+  const stderrSummaryMaxChars = config.stderrSummaryMaxChars ?? 500
+  assertPositiveInteger('stderrSummaryMaxChars', stderrSummaryMaxChars)
  let parsed: CodexHookConfig = {}
  try {
    const raw: unknown = JSON.parse(readFileSync(config.configPath, 'utf8'))
@@ -140,7 +149,7 @@ 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'),
--- 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 +204,29 @@ 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('rejects a non-positive or fractional stderrSummaryMaxChars at load', async () => {
+    const d = dir()
+    hooks(d, {})
+    for (const bad of [0, -5, 1.5, Number.NaN]) {
+      const adapter = new MockAdapter([])
+      await expect(harness(join(d, 'hooks.json'), adapter, { stderrSummaryMaxChars: bad }))
+        .rejects.toThrow(/hooks-codex: stderrSummaryMaxChars must be a positive integer/)
+    }
+  })
+
+  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 () => {
--- 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'
 }
 ```

--- 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)
    }
  }

--- 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) {
--- 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.
--- 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
--- 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))
 }
--- 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
--- 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 +398,47 @@ describe('dsh-subagent-acp', () => {
    await run.dispose()
  })

+  it('plugin-config dispose graces reach the run (SIGKILL escalation through the provider)', async () => {
+    // Same trap scenario as the direct startAcpRun escalation test, but the
+    // graces arrive via the PLUGIN CONFIG through the registered provider — so a
+    // regression that stops threading config into AcpRunSpec (falling back to
+    // the 6s/3s defaults) blows past the 4000ms bound and fails loud.
+    const tmp = mkdtempSync(join(tmpdir(), 'acp-cfg-trap-'))
+    const ready = join(tmp, 'trap-armed')
+    try {
+      const ctx = new Context()
+      await ctx.plugin(SubagentService)
+      await ctx.plugin(acp, {
+        providerName: 'acp',
+        command: process.execPath,
+        args: ['--import', tsxLoader, mockServer],
+        permission: 'reject',
+        env: { MOCK_TRAP_SIGTERM: '1', MOCK_TEXT: 'x', MOCK_READY_FILE: ready, TSX_TSCONFIG_PATH: repoTsconfig },
+        disposeEofGraceMs: 150,
+        disposeGraceMs: 150,
+      })
+      const run = ctx.subagents.start('acp', { prompt: [{ type: 'text', text: 'p' }], parent: fakeParent })
+      await waitForFile(ready)
+      await expect(Promise.race([
+        run.dispose(),
+        new Promise((_r, reject) => { setTimeout(() => { reject(new Error('dispose did not return — config graces not threaded to the run')) }, 4000) }),
+      ])).resolves.toBeUndefined()
+      await ctx.fiber.dispose()
+    } finally {
+      rmSync(tmp, { recursive: true, force: true })
+    }
+  })
+
+  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 +469,8 @@ 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 }) },
      },
    )
--- a/packages/web/tool-web/README.md
+++ b/packages/web/tool-web/README.md
@@ -8,7 +8,7 @@ Each tool is registered independently; a product that wants only one disables th

 | Tool | Args | Behavior |
 |---|---|---|
-| `web_search` | `query` (string) | Discovery. Returns an optional answer plus source URLs. `max_results` is **not** model-facing — the tool sets the bound (`WEB_SEARCH_MAX_RESULTS = 8`) and passes it to the seam. |
+| `web_search` | `query` (string) | Discovery. Returns an optional answer plus source URLs. `max_results` is **not** model-facing — the tool sets the bound (the `searchMaxResults` config, default 8) and passes it to the seam. |
 | `web_fetch` | `url` (string), `timeout_ms` (number, optional) | Retrieves a specific URL. HTML bodies are rendered to markdown-ish text; text bodies pass through. A non-2xx status is reported, not an error. |

 ## Config
@@ -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
--- 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)
 }
--- 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) }]
--- 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/)
+  })
+})
--- 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:^