subagent: carry inherited policy overrides in the child session header

Review fix (ds-review-bot critical #2 on #623): the first-turn event stamp
had a durability hole no turn anchoring can close — an idle SessionStart-
style injection persists a complete one-shot turn before any prompt turn
opens, so a crash in that window left a resumable-looking child with no
inherited policy, falling back to a possibly wider deployment default.

The captured overrides now ride the child's creation meta into its
immutable SessionHeader (sandboxMode/approvalPolicy, neutral strings at the
session boundary — the delegationDepth precedent), durable from the moment
the session exists: no listener ordering can starve the baseline and no
crash window can lose it. overrideOf(session) on both policy services
resolves fold(events past header.seedLength) ?? header baseline, validating
against the closed vocabulary on read; stampOverride and the prompt-submit
listener machinery are deleted. The header field rides both persistence
backends (JSONL header line; SQLite sessions columns, SCHEMA_VERSION 11 —
pre-release, no migration). pty-local reads through overrideOf so PTY
spawns see the baseline too.

Red-first: header-durability-before-any-turn test (the injection crash
window shape), baseline/seed-boundary/closed-vocabulary contract tests in
both service suites; the real-wall suite (race, veto, fork stale-seed,
grandchild) re-anchored on header assertions and green. The Agent Note's
Alternatives now records the superseded event-stamping iteration with the
review evidence; bilingual docs updated.

packages/cordis/tool-cordis/src/api-catalog.ts

@@ -152,11 +152,7 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
       },
       {
         signature: 'overrideOf(session: Session): ApprovalPolicy | undefined',
-        jsDoc: '/**\n * A session\'s approval-policy OVERRIDE — the fold alone, never the\n * configured default. The read half of delegation inheritance: the subagent\n * driver captures this synchronously at delegation, so a parent switch\n * racing the child\'s asynchronous creation belongs to the parent\'s future,\n * not to the child ([rationale](../../../.agents/notes/implemented/feature/2026-07-25-subagent-policy-inheritance.md)).\n * @param session - the session whose override chain to fold.\n * @returns the last switched policy, or `undefined` for a never-switched session.\n */',
-      },
-      {
-        signature: 'stampOverride(child: Session, policy: ApprovalPolicy): void',
-        jsDoc: '/**\n * Stamp a captured override onto a child session through the canonical\n * write path — the write half of delegation inheritance: a `\'never\'`\n * (headless/CI) parent must not mint children that fall back to a prompting\n * default. A child whose log (e.g. a fork seed) already folds to the policy\n * is left untouched. Callers must append inside an open child turn — a bare\n * between-turn event is crash-tail garbage on reload.\n * @param child - the child session the override is appended to.\n * @param policy - the captured {@link overrideOf} value to stamp.\n */',
+        jsDoc: '/**\n * A session\'s approval-policy OVERRIDE — the override chain alone, never\n * the configured default: the fold of the session\'s OWN switches (events\n * past the seed boundary — a fork seed\'s stale parent switch is subsumed by\n * the baseline captured after it), else the header\'s inherited delegation\n * baseline. The subagent driver stamps `overrideOf(parent.session)` into\n * each child\'s creation meta, so a `\'never\'` (headless/CI) parent cannot\n * mint children that fall back to a prompting default, at any depth\n * ([rationale](../../../.agents/notes/implemented/feature/2026-07-25-subagent-policy-inheritance.md)).\n * @param session - the session whose override chain to resolve.\n * @returns the effective override, or `undefined` for a session following\n *   the configured default.\n * @throws when the durable header baseline is outside the closed policy\n *   vocabulary (a corrupt or foreign log; durable-boundary validation).\n */',
       },
     ],
   },
@@ -496,11 +492,7 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
       },
       {
         signature: 'overrideOf(session: Session): SandboxMode | undefined',
-        jsDoc: '/**\n * A session\'s sandbox-mode OVERRIDE — the fold alone, never the deployment\n * default. The read half of delegation inheritance: the subagent driver\n * captures this synchronously at delegation, so a parent switch racing the\n * child\'s asynchronous creation belongs to the parent\'s future, not to the\n * child ([rationale](../../../.agents/notes/implemented/feature/2026-07-25-subagent-policy-inheritance.md)).\n * @param session - the session whose override chain to fold.\n * @returns the last switched mode, or `undefined` for a never-switched session.\n */',
-      },
-      {
-        signature: 'stampOverride(child: Session, mode: SandboxMode): void',
-        jsDoc: '/**\n * Stamp a captured override onto a child session through the canonical\n * write path — the write half of delegation inheritance: a child agent runs\n * under the policy its delegating parent was switched to, not under the\n * (possibly wider) deployment default. A child whose log (e.g. a fork seed)\n * already folds to the mode is left untouched. Callers must append inside\n * an open child turn — a bare between-turn event is crash-tail garbage on\n * reload.\n * @param child - the child session the override is appended to.\n * @param mode - the captured {@link overrideOf} value to stamp.\n */',
+        jsDoc: '/**\n * A session\'s sandbox-mode OVERRIDE — the override chain alone, never the\n * deployment default: the fold of the session\'s OWN switches (events past\n * the seed boundary — a fork seed\'s stale parent switch is subsumed by the\n * baseline captured after it), else the header\'s inherited delegation\n * baseline. The subagent driver stamps `overrideOf(parent.session)` into\n * each child\'s creation meta, so the chain collapses one level per\n * delegation and a tightened parent binds children at any depth\n * ([rationale](../../../.agents/notes/implemented/feature/2026-07-25-subagent-policy-inheritance.md)).\n * @param session - the session whose override chain to resolve.\n * @returns the effective override, or `undefined` for a session following\n *   the deployment default.\n * @throws when the durable header baseline is outside the closed mode\n *   vocabulary (a corrupt or foreign log; durable-boundary validation).\n */',
       },
     ],
   },
@@ -1514,7 +1506,7 @@ export const TYPE_API: readonly TypeApiEntry[] = [
   },
   {
     name: 'CreateAgentOptions',
-    declaration: 'export interface CreateAgentOptions {\n    readonly sessionId: SessionId;\n    readonly meta?: {\n        readonly cwd?: string;\n        readonly parentSession?: SessionId;\n        readonly seedLength?: number;\n        readonly delegationDepth?: number;\n    };\n    readonly seed?: readonly SessionEvent[];\n    readonly agentOptions?: AgentOptions;\n    readonly signal?: AbortSignal;\n    readonly setup?: (agentCtx: Context) => Promise<void> | void;\n}',
+    declaration: 'export interface CreateAgentOptions {\n    readonly sessionId: SessionId;\n    readonly meta?: {\n        readonly cwd?: string;\n        readonly parentSession?: SessionId;\n        readonly seedLength?: number;\n        readonly delegationDepth?: number;\n        readonly sandboxMode?: string;\n        readonly approvalPolicy?: string;\n    };\n    readonly seed?: readonly SessionEvent[];\n    readonly agentOptions?: AgentOptions;\n    readonly signal?: AbortSignal;\n    readonly setup?: (agentCtx: Context) => Promise<void> | void;\n}',
   },
   {
     name: 'CreateGoalRequest',
@@ -1522,7 +1514,7 @@ export const TYPE_API: readonly TypeApiEntry[] = [
   },
   {
     name: 'CreateSessionOptions',
-    declaration: 'export interface CreateSessionOptions {\n    readonly seed?: readonly SessionEvent[];\n    readonly meta?: {\n        readonly cwd?: string;\n        readonly parentSession?: SessionId;\n        readonly createdAt?: number;\n        readonly seedLength?: number;\n        readonly delegationDepth?: number;\n    };\n}',
+    declaration: 'export interface CreateSessionOptions {\n    readonly seed?: readonly SessionEvent[];\n    readonly meta?: {\n        readonly cwd?: string;\n        readonly parentSession?: SessionId;\n        readonly createdAt?: number;\n        readonly seedLength?: number;\n        readonly delegationDepth?: number;\n        readonly sandboxMode?: string;\n        readonly approvalPolicy?: string;\n    };\n}',
   },
   {
     name: 'DiffCallView',
@@ -2002,7 +1994,7 @@ export const TYPE_API: readonly TypeApiEntry[] = [
   },
   {
     name: 'SessionHeader',
-    declaration: 'export interface SessionHeader {\n    readonly version: number;\n    readonly id: SessionId;\n    readonly createdAt: number;\n    readonly cwd?: string;\n    readonly parentSession?: SessionId;\n    readonly seedLength?: number;\n    readonly delegationDepth?: number;\n}',
+    declaration: 'export interface SessionHeader {\n    readonly version: number;\n    readonly id: SessionId;\n    readonly createdAt: number;\n    readonly cwd?: string;\n    readonly parentSession?: SessionId;\n    readonly seedLength?: number;\n    readonly delegationDepth?: number;\n    readonly sandboxMode?: string;\n    readonly approvalPolicy?: string;\n}',
   },
   {
     name: 'SessionId',