Expose audited hardcoded tunables as plugin config

The audit swept every packages/*/* plugin for the new AGENTS.md
convention (no hardcoded tunables in plugins) and exposes each finding
as a defaulted, validated Config field. Defaults are the previously
hardcoded values throughout, so no deployment or golden changes.

- tool-fs (had NO Config): readLimit, readMaxLineLength, readMaxBytes,
  readStreamMinSize. The caps thread through ReadToolCaps/ReadWindow —
  read-render already documented that the consumer applies the caps, so
  they become explicit per-request fields.
- tool-web: searchMaxResults (WEB_SEARCH_MAX_RESULTS stays as the
  schemastery default). Also fixes the stale GREP_LIMIT references in
  search.ts and the web-capability-seam RFC (no such constant exists).
- bash-local: graceMs (SIGTERM->SIGKILL escalation grace). The
  RunInternals.graceMs test seam is gone: graceMs is now a required
  SpawnSpec field filled from config, so tests exercise the real
  config path and the defaults live in exactly one place.
- subagent-acp: disposeEofGraceMs / disposeGraceMs. The AcpRunSpec
  fields become required for the same one-defaulting-layer reason.
- session-persistence-sqlite: journalMode ('wal' default; the
  rollback-journal modes serve filesystems where WAL's shared-memory
  files do not work, e.g. network mounts).
- hooks-claude + hooks-codex: stderrSummaryMaxChars for the persisted
  hook/result stderr summary. The duplicated summarize() helpers merge
  into hook-protocol's summarizeStderr(stderr, maxChars), beside the
  HookResultRecord field it feeds, with the bound parameterized the
  same way runHook's defaultTimeoutMs already is.
- compact-basic: charsPerToken for the token estimator (default 4, the
  English-text heuristic; CJK-heavy deployments need ~1-2 or compaction
  fires far too late). Also corrects the BasicCompactService class doc,
  which claimed defaults the required-field config never had.
- fs-local: deletes the dead STREAM_MIN_SIZE constant and the dead
  FsIoInternals.streamMinSize seam — the read-routing bound lives in
  the consumer (tool-fs), where it is now config. This is item 1 of
  the proposed prune-write-only-fs-surface RFC, annotated accordingly.

Every new field gets range validation (following the existing
assertPositiveFinite pattern), a README row, and tests covering the
configured behavior, the schema default, and load-time rejection.

packages/web/tool-web/README.md

@@ -17,6 +17,7 @@ Each tool is registered independently; a product that wants only one disables th
 |---|---|---|
 | `search` | `true` | Register `web_search`. |
 | `fetch` | `true` | Register `web_fetch`. |
+| `searchMaxResults` | `8` | Upper bound on sources returned by one `web_search` call (the seam truncates a longer provider list and flags it). |
 
 ```yaml
 - id: tool-web

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)
 }

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) }]

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/)
+  })
+})