refactor: identify and freeze messages at creation

packages/llm/llm/tests/message.spec.ts

@@ -0,0 +1,99 @@
+import { describe, expect, it } from 'vitest'
+import {
+  CallId,
+  createAssistantMessage,
+  createToolResultMessage,
+  createUserMessage,
+  freezeMessage,
+  MessageId,
+} from '@deepseek-ai/dsh-llm'
+
+describe('message construction', () => {
+  it('assigns identity immediately and returns a detached deep-frozen message', () => {
+    const input = {
+      content: [{ type: 'text' as const, text: 'original' }],
+      source: { kind: 'plugin' as const, plugin: 'test' },
+    }
+
+    const message = createUserMessage(input)
+
+    expect(message.id).toEqual(expect.any(String))
+    expect(message.role).toBe('user')
+    expect(message.id).not.toHaveLength(0)
+    expect(message).not.toBe(input)
+    expect(Object.isFrozen(message)).toBe(true)
+    expect(Object.isFrozen(message.content)).toBe(true)
+    expect(Object.isFrozen(message.content[0])).toBe(true)
+    expect(Object.isFrozen(message.source)).toBe(true)
+
+    input.content[0]!.text = 'caller mutation'
+    expect(message.content).toEqual([{ type: 'text', text: 'original' }])
+    expect(() => {
+      (message.content[0] as { text: string }).text = 'observer mutation'
+    }).toThrow()
+  })
+
+  it('freezes an existing identity without minting a replacement', () => {
+    const id = MessageId('existing')
+    const input = {
+      id,
+      role: 'assistant' as const,
+      content: [{ type: 'text' as const, text: 'answer' }],
+      source: { kind: 'model' as const, provider: 'test', model: 'test' },
+    }
+
+    const message = freezeMessage(input)
+
+    expect(message).not.toBe(input)
+    expect(message.id).toBe(id)
+    expect(Object.isFrozen(message)).toBe(true)
+    expect(Object.isFrozen(message.content[0])).toBe(true)
+  })
+
+  it('fixes the assistant role and model source kind at creation', () => {
+    const message = createAssistantMessage({
+      content: [{ type: 'text', text: 'answer' }],
+      source: {
+        provider: 'test-provider',
+        model: 'test-model',
+        replayState: { request: 1 },
+      },
+    })
+
+    expect(message).toMatchObject({
+      role: 'assistant',
+      source: {
+        kind: 'model',
+        provider: 'test-provider',
+        model: 'test-model',
+        replayState: { request: 1 },
+      },
+    })
+    expect(message.id).not.toHaveLength(0)
+    expect(Object.isFrozen(message)).toBe(true)
+    expect(Object.isFrozen(message.source)).toBe(true)
+  })
+
+  it('couples tool-result content and provenance to one call identity', () => {
+    const callId = CallId('call-1')
+    const message = createToolResultMessage({
+      callId,
+      content: [{ type: 'text', text: 'result' }],
+      isError: false,
+    })
+
+    expect(message).toMatchObject({
+      role: 'user',
+      source: { kind: 'tool', callId },
+      content: [{
+        type: 'tool-result',
+        toolCallId: callId,
+        content: [{ type: 'text', text: 'result' }],
+        isError: false,
+      }],
+    })
+    expect(message.id).not.toHaveLength(0)
+    expect(Object.isFrozen(message)).toBe(true)
+    expect(Object.isFrozen(message.content[0])).toBe(true)
+  })
+})