Merge remote-tracking branch 'origin/master' into codex/project-instruction-files

# Conflicts:
#	AGENTS.md
#	docs/config-catalog.md
#	docs/cordis-catalog/events.md
#	docs/cordis-catalog/services.md
#	docs/core-data-structures/core.md
#	docs/event-producer-consumer.md
#	docs/persistence-catalog.md
#	docs/rfc/implemented/architecture/2026-07-05-reconstructable-requests.md
#	docs/rfc/implemented/feature/2026-06-15-code-mode.md
#	docs/rfc/implemented/feature/2026-06-30-hook-bridges.md
#	docs/rfc/implemented/feature/2026-06-30-interception-seams.md
#	docs/rfc/implemented/feature/2026-07-08-repeat-tool-guard.md
#	docs/rfc/proposed/simplification/2026-07-04-prune-dead-core-spine-surface.md
#	examples/AGENTS.md
#	examples/acp-agent/cordis.yml
#	examples/acp-agent/tests/acp.snapshot.ts
#	examples/echo-agent/cordis.yml
#	examples/sandbox-acp-agent/cordis.yml
#	packages/cordis/tool-cordis/src/api-catalog.ts
#	packages/core/agent-core/README.md
#	packages/core/agent-core/src/index.ts
#	packages/core/agent-loop/README.md
#	packages/core/agent-loop/src/loop.ts
#	packages/core/agent-loop/tests/interception.spec.ts
#	packages/core/agent/src/types.ts
#	packages/core/tools/README.md
#	packages/core/tools/src/code-mode.ts
#	packages/core/tools/src/index.ts
#	packages/fs/fs-local/src/index.ts
#	packages/fs/fs/README.md
#	packages/fs/fs/src/index.ts
#	packages/guard/repeat-tool-guard/README.md
#	packages/guard/repeat-tool-guard/src/index.ts
#	packages/hooks/hooks-claude/src/index.ts
#	packages/hooks/hooks-codex/src/index.ts
#	packages/ui/acp-agent/src/index.ts

packages/core/session/tests/session.spec.ts

@@ -103,9 +103,6 @@ describe('Session', () => {
     const before = structuredClone(session.events)
 
     // A misbehaving consumer tries to mutate the messages it was handed.
-    // Derived messages are frozen shared projections (cloned once off the
-    // log, then deep-frozen): every mutation attempt THROWS in strict mode —
-    // isolation by unrepresentability, not by per-call cloning.
     const messages = session.deriveMessages()
     const userBlock = messages[0]!.content[0]!
     expect(() => { if (userBlock.type === 'text') userBlock.text = 'HACKED' }).toThrow(TypeError)
@@ -154,11 +151,8 @@ describe('Session', () => {
   it('rejects a surface-eligible append with no surfaceOp marker (runtime guard for the union-widening loophole)', () => {
     const session = new Session(SessionId('s5b'))
     session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
-    // The typed overload makes surfaceOp mandatory only when the type argument is
-    // a SPECIFIC SurfaceEventType literal. A caller iterating raw events widens it
-    // to the SessionEventType union, where the conditional rest collapses to
-    // optional — the exact shape `for (const e of log) append(e.type, e.data)`
-    // produces. Reproduce that here and assert the runtime guard rejects it.
+    // A widened SessionEventType bypasses the overload's conditional requirement,
+    // so the runtime guard must still reject the missing surface marker.
     const widenedType = 'user/message' as SessionEventType
     expect(() => session.append(widenedType, { content: [{ type: 'text', text: 'hi' }], source: { kind: 'user' } }))
       .toThrow(/surface-eligible and requires a surfaceOp marker/)
@@ -685,10 +679,8 @@ describe('SessionStore', () => {
   })
 
   it('enter() rejects a stale prepared session whose id is already live (no overwrite)', async () => {
-    // prepare()/enter() are public cross-package primitives that a caller may
-    // separate with arbitrary work. A stale prepared session must NOT overwrite
-    // a live store entry of the same id — its detach disposer would later delete
-    // the REAL session, breaking the store-uniqueness invariant.
+    // A stale prepared object must not replace the live same-id entry; its later
+    // detach would otherwise remove the wrong session.
     const ctx = new Context()
     await ctx.plugin(SessionStore)
     const stale = ctx.sessions.prepare(SessionId('racy'))