refactor: identify and freeze messages at creation

packages/pty/pty/tests/service.spec.ts

@@ -1,7 +1,7 @@
 import { describe, expect, expectTypeOf, it } from 'vitest'
 import { Context } from 'cordis'
 import { Session, SessionId } from '@deepseek-ai/dsh-session'
-import AgentRegistry, { AgentMessageId } from '@deepseek-ai/dsh-agent'
+import AgentRegistry, {} from '@deepseek-ai/dsh-agent'
 import type { Agent } from '@deepseek-ai/dsh-agent'
 import PtyService, { PtyBackendCleanupError, PtyError, PtySessionId } from '@deepseek-ai/dsh-pty'
 import type {
@@ -28,10 +28,10 @@ function stubAgent(ctx: Context, rawId: string): Agent {
     status: 'idle',
     acceptsNextStep: false,
     ctx: scopeFiber.ctx,
-    followup: () => AgentMessageId('stub'),
-    steer: () => AgentMessageId('stub'),
-    inject: () => AgentMessageId('stub'),
-    send: () => AgentMessageId('stub'),
+    followup: () => {},
+    steer: () => {},
+    inject: () => {},
+    send: () => {},
     cancel() {},
     whenIdle: () => Promise.resolve(),
   }