fix: complete immutable message migration

packages/llm/llm-pi-ai/tests/convert.spec.ts

@@ -364,7 +364,7 @@ describe('toPiContext', () => {
   it.each([
     ['provider', { ...validReplay, provider: 'openai' }],
     ['model', { ...validReplay, model: 'deepseek-v4-pro' }],
-  ])('rejects replay metadata whose %s differs from assistant provenance', (field, replayState) => {
+  ])('rejects replay metadata whose %s differs from assistant source', (field, replayState) => {
     try {
       toPiContext({
         provider: 'deepseek',
@@ -382,7 +382,7 @@ describe('toPiContext', () => {
     } catch (error: unknown) {
       expect(error).toBeInstanceOf(LlmError)
       expect((error as LlmError).code).toBe('INVALID_REPLAY_STATE')
-      expect((error as Error).message).toContain(`${field} does not match assistant provenance`)
+      expect((error as Error).message).toContain(`${field} does not match assistant source`)
     }
   })
 

packages/llm/llm-retry/tests/retry.spec.ts

@@ -216,9 +216,10 @@ describe('provider-routed retry policy', () => {
     expect(agent.session.events.filter(item => item.type === 'step/start').map(item => item.data))
       .toEqual([{ turn: 1, step: 1 }, { turn: 2, step: 1 }])
     expect(agent.session.deriveMessages().at(-1)).toEqual({
+      id: expect.any(String) as unknown,
       role: 'assistant',
       content: [{ type: 'text', text: 'done' }],
-      provenance: { provider: 'mock', model: 'mock' },
+      source: { kind: 'model', provider: 'mock', model: 'mock' },
     })
   })
 
@@ -296,7 +297,7 @@ describe('provider-routed retry policy', () => {
     expect(agent.session.deriveMessages().at(-1)).toMatchObject({
       role: 'assistant',
       content: [{ type: 'text', text: 'recovered' }],
-      provenance: { provider: 'mock', model: 'mock' },
+      source: { kind: 'model', provider: 'mock', model: 'mock' },
     })
   })
 

packages/llm/llm/src/message.ts

@@ -128,8 +128,8 @@ export function createAssistantMessage(
     role: 'assistant',
     content: input.content,
     source: {
-      ...input.source,
       kind: 'model',
+      ...input.source,
     },
   })
 }