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/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)
     })