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/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)
     }
   }
 

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) {