subagent: seed inherited policy events at creation

The parent implementation introduced sandboxMode and approvalPolicy as generic SessionHeader fields, then propagated those fields through both persistence backends, session-query indexes, collision checks, policy-specific seed-boundary folds, catalogs, and a broad test matrix. That storage plane is unnecessary: Session already accepts a validated constructor seed, and persistence captures that seed when the session is announced before committing its first batch.

Capture each parent override synchronously at delegation, append source-tagged sandbox/mode and approval/policy records after the optional fork prefix, and create the child with that combined seed. Keeping header.seedLength at the original fork-prefix length preserves lineage while ordinary last-event-wins folds make the inherited records outrank stale parent history and remain subordinate to later child switches. Unswitched parents still stamp nothing, so children continue to follow deployment defaults.

Remove the generic header fields and every persistence/query/schema branch built around them. Collapse the inheritance suite from ten leaking scenarios to four owned-context cases covering real filesystem confinement, stale fork precedence, delegation-time capture, and the no-override path. The assembled headless snapshot now asserts the persisted inheritance event directly.

This keeps the security behavior while restoring policy ownership to the existing event log and deleting the speculative durability machinery that the original tests did not exercise.

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

@@ -152,7 +152,7 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
       },
       {
         signature: 'overrideOf(session: Session): ApprovalPolicy | undefined',
-        jsDoc: '/**\n * {@link approvalOverrideOf} surfaced on the service, for consumers that\n * reach the seam through `ctx.get(\'approval\')` (the subagent driver\'s\n * delegation capture) rather than a value import.\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 */',
+        jsDoc: '/**\n * Read the session override without applying the configured default.\n * @param session - session whose log supplies the override.\n * @returns the last logged policy, or `undefined` without one.\n */',
       },
     ],
   },
@@ -411,8 +411,8 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
     summary: 'Owns the deployment\'s permission presets and their write path.',
     methods: [
       {
-        signature: 'current(session: Session): string',
-        jsDoc: '/**\n * Resolve the preset matching the effective knob values — the same\n * override chains execution reads (own post-seed switches, else the\n * inherited header baseline, else the composition defaults), so a\n * delegated child\'s inherited knobs derive its real preset. A\n * still-matching last selection wins shared-bundle ties, scoped like the\n * knob chains: a delegation child (header baselines present) ignores\n * seed-carried selections as stale parent history, while a generic fork\n * child keeps them alongside its seed-carried knobs; otherwise the first\n * table match wins, or {@link CUSTOM_PRESET} when no entry matches.\n * @param session - the session whose preset to derive.\n * @returns the effective preset name, or `custom` when nothing matches.\n */',
+        signature: 'current(events: readonly SessionEvent[]): string',
+        jsDoc: '/**\n * Resolve the preset matching the effective knob values. A still-matching\n * last selection wins shared-bundle ties; otherwise the first table match\n * wins, or {@link CUSTOM_PRESET} when no entry matches.\n * @param events - the session\'s events in log order.\n * @returns the effective preset name, or `custom` when nothing matches.\n */',
       },
       {
         signature: 'resolve(name: string): PresetSpec',
@@ -500,11 +500,11 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
     methods: [
       {
         signature: 'resolve(request: SandboxPolicyRequest = {}): SandboxExecutionPolicy',
-        jsDoc: '/**\n * Resolve the complete policy for one capability call. An approved explicit\n * mode outranks the session\'s override chain ({@link overrideOf}: own\n * post-seed switches, else the inherited header baseline), which outranks\n * the deployment default. A session cwd is its workspace-write boundary;\n * the configured root is the fallback for agentless calls and sessions\n * without a cwd.\n * @param request - optional session and approved mode override.\n * @returns the fully resolved per-call mode and absolute workspace root.\n */',
+        jsDoc: '/**\n * Resolve the complete policy for one capability call. An approved explicit\n * mode outranks the session\'s last `sandbox/mode` event, which outranks the\n * deployment default. A session cwd is its workspace-write boundary; the\n * configured root is the fallback for agentless calls and sessions without a\n * cwd.\n * @param request - optional session and approved mode override.\n * @returns the fully resolved per-call mode and absolute workspace root.\n */',
       },
       {
         signature: 'overrideOf(session: Session): SandboxMode | undefined',
-        jsDoc: '/**\n * {@link sandboxOverrideOf} surfaced on the service, for consumers that\n * reach policy through `ctx.get(\'sandboxPolicy\')` (the subagent driver\'s\n * delegation capture, pty-local) rather than a value import.\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 */',
+        jsDoc: '/**\n * Read the session override without applying the deployment default.\n * @param session - session whose log supplies the override.\n * @returns the last logged mode, or `undefined` without one.\n */',
       },
     ],
   },
@@ -1593,7 +1593,7 @@ 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        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}',
+    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}',
   },
   {
     name: 'CreateGoalRequest',
@@ -1601,7 +1601,7 @@ 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        readonly sandboxMode?: string;\n        readonly approvalPolicy?: string;\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    };\n}',
   },
   {
     name: 'DiffCallView',
@@ -2109,7 +2109,7 @@ 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    readonly sandboxMode?: string;\n    readonly approvalPolicy?: string;\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}',
   },
   {
     name: 'SessionId',