feat: align AI chat protocol with Vercel AI SDK, remove custom types and schemas

- Re-export ModelMessage, ToolCallPart, ToolResultPart, TextStreamPart from 'ai'
- Remove AiChatRequestSchema/AiChatResponseSchema (use Vercel wire protocol)
- Update IAIService/LLMAdapter to use Vercel types
- Deprecate AIMessage, AIToolCall, AIToolResult, AIStreamEvent as aliases
- Remove aiChat from IObjectStackAPI, client SDK, and DEFAULT_AI_ROUTES
- Keep NLQ/Suggest/Insights protocols (ObjectStack-specific)
- Update all tests (6772 pass)
- Update CHANGELOG.md and ROADMAP.md

Agent-Logs-Url: https://github.com/objectstack-ai/spec/sessions/2515d700-01d1-4303-8678-41f0ce9674da

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

CHANGELOG.md

@@ -7,6 +7,32 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+- **AI Chat Protocol Aligned with Vercel AI SDK** — Removed custom AI chat protocol
+  types and Zod schemas (`AIMessage`, `AIToolCall`, `AIStreamEvent`,
+  `AiChatRequestSchema`, `AiChatResponseSchema`) from `@objectstack/spec`. The
+  canonical message, tool-call, and streaming types are now re-exported from the
+  Vercel AI SDK (`ai` v6):
+  - `ModelMessage` replaces `AIMessage`
+  - `ToolCallPart` replaces `AIToolCall`
+  - `ToolResultPart` replaces `AIToolResult`
+  - `TextStreamPart<ToolSet>` replaces `AIStreamEvent`
+  - `IAIService` and `LLMAdapter` method signatures now accept `ModelMessage[]`
+    and return `TextStreamPart<ToolSet>` for streaming
+  - Deprecated type aliases preserved for migration convenience
+  - NLQ, Suggest, and Insights protocols (ObjectStack-specific) are retained
+
+### Removed
+- `AiChatRequestSchema` / `AiChatResponseSchema` Zod schemas from
+  `@objectstack/spec/api` — the AI chat wire protocol now uses Vercel AI SDK's
+  data stream format (`toDataStreamResponse()`)
+- `aiChat` method from `IObjectStackAPI` and client SDK — consumers should use
+  `@ai-sdk/react/useChat` directly
+- AI `/chat` endpoint from `DEFAULT_AI_ROUTES` plugin REST API definition
+
+### Added
+- `ai` v6 as a dependency of `@objectstack/spec` for type re-exports
+
 ## [4.0.1] — 2026-03-31
 
 ### Fixed

ROADMAP.md

@@ -1,6 +1,6 @@
 # ObjectStack Protocol — Road Map
 
-> **Last Updated:** 2026-03-31  
+> **Last Updated:** 2026-04-01  
 > **Current Version:** v4.0.1  
 > **Status:** Protocol Specification Complete · Runtime Implementation In Progress
 

packages/client/src/index.ts

@@ -62,8 +62,6 @@ import {
   MarkAllNotificationsReadResponse,
   AiNlqRequest,
   AiNlqResponse,
-  AiChatRequest,
-  AiChatResponse,
   AiSuggestRequest,
   AiSuggestResponse,
   AiInsightsRequest,
@@ -1209,17 +1207,7 @@ export class ObjectStackClient {
       return this.unwrapResponse<AiNlqResponse>(res);
     },
 
-    /**
-     * Multi-turn AI chat
-     */
-    chat: async (request: AiChatRequest): Promise<AiChatResponse> => {
-      const route = this.getRoute('ai');
-      const res = await this.fetch(`${this.baseUrl}${route}/chat`, {
-        method: 'POST',
-        body: JSON.stringify(request)
-      });
-      return this.unwrapResponse<AiChatResponse>(res);
-    },
+    // AI chat method removed — use Vercel AI SDK `useChat()` / `@ai-sdk/react` directly.
 
     /**
      * AI-powered field value suggestions
@@ -1826,8 +1814,6 @@ export type {
   ListNotificationsResponse,
   AiNlqRequest,
   AiNlqResponse,
-  AiChatRequest,
-  AiChatResponse,
   AiSuggestRequest,
   AiSuggestResponse,
   AiInsightsRequest,

packages/spec/src/api/plugin-rest-api.test.ts

@@ -571,13 +571,10 @@ describe('plugin-rest-api.zod', () => {
       expect(DEFAULT_AI_ROUTES.service).toBe('ai');
       expect(DEFAULT_AI_ROUTES.category).toBe('ai');
       expect(DEFAULT_AI_ROUTES.methods).toContain('aiNlq');
-      expect(DEFAULT_AI_ROUTES.methods).toContain('aiChat');
+      // aiChat removed — wire protocol aligned with Vercel AI SDK
       expect(DEFAULT_AI_ROUTES.methods).toContain('aiSuggest');
       expect(DEFAULT_AI_ROUTES.methods).toContain('aiInsights');
-      expect(DEFAULT_AI_ROUTES.endpoints).toHaveLength(4);
-      // AI endpoints should have extended timeouts
-      const chatEndpoint = DEFAULT_AI_ROUTES.endpoints?.find(e => e.handler === 'aiChat');
-      expect(chatEndpoint?.timeout).toBe(60000);
+      expect(DEFAULT_AI_ROUTES.endpoints).toHaveLength(3);
     });
 
     it('should validate DEFAULT_I18N_ROUTES', () => {

packages/spec/src/api/plugin-rest-api.zod.ts

@@ -1398,7 +1398,7 @@ export const DEFAULT_AI_ROUTES: RestApiRouteRegistration = {
   prefix: '/api/v1/ai',
   service: 'ai',
   category: 'ai',
-  methods: ['aiNlq', 'aiChat', 'aiSuggest', 'aiInsights'],
+  methods: ['aiNlq', 'aiSuggest', 'aiInsights'],
   authRequired: true,
   endpoints: [
     {
@@ -1415,20 +1415,8 @@ export const DEFAULT_AI_ROUTES: RestApiRouteRegistration = {
       timeout: 30000,
       cacheable: false,
     },
-    {
-      method: 'POST',
-      path: '/chat',
-      handler: 'aiChat',
-      category: 'ai',
-      public: false,
-      summary: 'AI chat interaction',
-      description: 'Sends a message to the AI assistant and receives a response',
-      tags: ['AI'],
-      requestSchema: 'AiChatRequestSchema',
-      responseSchema: 'AiChatResponseSchema',
-      timeout: 60000,
-      cacheable: false,
-    },
+    // AI chat route removed — wire protocol aligned with Vercel AI SDK.
+    // The chat endpoint should use Vercel's `toDataStreamResponse()` directly.
     {
       method: 'POST',
       path: '/suggest',

packages/spec/src/api/protocol.test.ts

@@ -54,8 +54,6 @@ import {
   // AI
   AiNlqRequestSchema,
   AiNlqResponseSchema,
-  AiChatRequestSchema,
-  AiChatResponseSchema,
   AiSuggestRequestSchema,
   AiSuggestResponseSchema,
   AiInsightsRequestSchema,
@@ -285,11 +283,7 @@ describe('ObjectStack Protocol', () => {
       query: { object: 'task', where: { status: 'open' } },
       explanation: 'Find all tasks with open status', confidence: 0.92,
     }).success).toBe(true);
-    expect(AiChatRequestSchema.safeParse({ message: 'How many tasks are overdue?', conversationId: 'c1' }).success).toBe(true);
-    expect(AiChatResponseSchema.safeParse({
-      message: 'There are 5 overdue tasks.', conversationId: 'c1',
-      actions: [{ type: 'navigate', label: 'View overdue tasks' }],
-    }).success).toBe(true);
+    // AiChatRequestSchema/AiChatResponseSchema removed — chat protocol aligned with Vercel AI SDK
     expect(AiSuggestRequestSchema.safeParse({ object: 'task', field: 'priority', partial: 'hi' }).success).toBe(true);
     expect(AiSuggestResponseSchema.safeParse({
       suggestions: [{ value: 'high', label: 'High', confidence: 0.95, reason: 'Matches partial input' }],

packages/spec/src/api/protocol.zod.ts

@@ -851,21 +851,10 @@ export const AiNlqResponseSchema = z.object({
   suggestions: z.array(z.string()).optional().describe('Suggested follow-up queries'),
 });
 
-export const AiChatRequestSchema = z.object({
-  message: z.string().describe('User message'),
-  conversationId: z.string().optional().describe('Conversation ID for context'),
-  context: z.record(z.string(), z.unknown()).optional().describe('Additional context data'),
-});
-
-export const AiChatResponseSchema = z.object({
-  message: z.string().describe('Assistant response message'),
-  conversationId: z.string().describe('Conversation ID'),
-  actions: z.array(z.object({
-    type: z.string().describe('Action type'),
-    label: z.string().describe('Action display label'),
-    data: z.record(z.string(), z.unknown()).optional().describe('Action data'),
-  })).optional().describe('Suggested actions'),
-});
+// AiChatRequestSchema and AiChatResponseSchema have been removed.
+// The AI chat wire protocol is now fully aligned with the Vercel AI SDK (`ai`).
+// Frontend consumers should use `@ai-sdk/react/useChat` directly.
+// See: https://ai-sdk.dev/docs
 
 export const AiSuggestRequestSchema = z.object({
   object: z.string().describe('Object name for context'),
@@ -1264,8 +1253,6 @@ export type MarkAllNotificationsReadResponse = z.infer<typeof MarkAllNotificatio
 // AI Types
 export type AiNlqRequest = z.input<typeof AiNlqRequestSchema>;
 export type AiNlqResponse = z.infer<typeof AiNlqResponseSchema>;
-export type AiChatRequest = z.input<typeof AiChatRequestSchema>;
-export type AiChatResponse = z.infer<typeof AiChatResponseSchema>;
 export type AiSuggestRequest = z.input<typeof AiSuggestRequestSchema>;
 export type AiSuggestResponse = z.infer<typeof AiSuggestResponseSchema>;
 export type AiInsightsRequest = z.input<typeof AiInsightsRequestSchema>;
@@ -1416,9 +1403,8 @@ export interface ObjectStackProtocol {
   markNotificationsRead?(request: MarkNotificationsReadRequest): Promise<MarkNotificationsReadResponse>;
   markAllNotificationsRead?(request: MarkAllNotificationsReadRequest): Promise<MarkAllNotificationsReadResponse>;
 
-  // AI (optional)
+  // AI (optional — chat is now handled by Vercel AI SDK wire protocol)
   aiNlq?(request: AiNlqRequest): Promise<AiNlqResponse>;
-  aiChat?(request: AiChatRequest): Promise<AiChatResponse>;
   aiSuggest?(request: AiSuggestRequest): Promise<AiSuggestResponse>;
   aiInsights?(request: AiInsightsRequest): Promise<AiInsightsResponse>;