diff --git a/web/src/api/chatRetry.test.ts b/web/src/api/chatRetry.test.ts
new file mode 100644
index 00000000..694a9261
--- /dev/null
+++ b/web/src/api/chatRetry.test.ts
@@ -0,0 +1,22 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { shouldAutoRetry, autoRetryDelayMs, fallbackErrorClass } from './chatRetry';
+
+test('shouldAutoRetry: transient only, max 2', () => {
+  assert.equal(shouldAutoRetry({ class: 'transient' }, 0), true);
+  assert.equal(shouldAutoRetry({ class: 'transient' }, 1), true);
+  assert.equal(shouldAutoRetry({ class: 'transient' }, 2), false);
+  assert.equal(shouldAutoRetry({ class: 'fatal' }, 0), false);
+  assert.equal(shouldAutoRetry({ class: 'resumable' }, 0), false);
+});
+
+test('autoRetryDelayMs: 1s then 2s', () => {
+  assert.equal(autoRetryDelayMs(0), 1000);
+  assert.equal(autoRetryDelayMs(1), 2000);
+});
+
+test('fallbackErrorClass: network → transient, workspace → resumable', () => {
+  assert.equal(fallbackErrorClass({ network: true }), 'transient');
+  assert.equal(fallbackErrorClass({ workspaceId: 'research_1' }), 'resumable');
+  assert.equal(fallbackErrorClass({}), 'fatal');
+});
diff --git a/web/src/api/chatRetry.ts b/web/src/api/chatRetry.ts
new file mode 100644
index 00000000..22fcffb6
--- /dev/null
+++ b/web/src/api/chatRetry.ts
@@ -0,0 +1,21 @@
+import type { ChatErrorInfo } from '../types/workbench';
+
+export function shouldAutoRetry(
+  info: Pick<ChatErrorInfo, 'class'>,
+  attemptIndex: number,
+): boolean {
+  return info.class === 'transient' && attemptIndex < 2;
+}
+
+export function autoRetryDelayMs(attemptIndex: number): number {
+  return attemptIndex === 0 ? 1000 : 2000;
+}
+
+export function fallbackErrorClass(criteria: {
+  network?: boolean;
+  workspaceId?: string;
+}): ChatErrorInfo['class'] {
+  if (criteria.network) return 'transient';
+  if (criteria.workspaceId) return 'resumable';
+  return 'fatal';
+}
diff --git a/web/src/api/chatStream.test.ts b/web/src/api/chatStream.test.ts
new file mode 100644
index 00000000..858b9dca
--- /dev/null
+++ b/web/src/api/chatStream.test.ts
@@ -0,0 +1,19 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { parseSSEChunk } from './chatStream';
+
+test('parseSSEChunk: parses event and data lines', () => {
+  const raw =
+    'event: phase\ndata: {"type":"phase","phase":{"phase_id":"intent_recognizing","message":"正在研判您的意图与项目上下文..."}}\n\n';
+  const { events, rest } = parseSSEChunk(raw);
+  assert.equal(rest, '');
+  assert.equal(events.length, 1);
+  assert.equal(events[0].type, 'phase');
+  assert.equal(events[0].phase?.phase_id, 'intent_recognizing');
+});
+
+test('parseSSEChunk: keeps incomplete frame in rest', () => {
+  const { events, rest } = parseSSEChunk('event: delta\ndata: {"type":"delta"');
+  assert.equal(events.length, 0);
+  assert.ok(rest.includes('event: delta'));
+});
diff --git a/web/src/api/chatStream.ts b/web/src/api/chatStream.ts
new file mode 100644
index 00000000..d4fa10a3
--- /dev/null
+++ b/web/src/api/chatStream.ts
@@ -0,0 +1,157 @@
+import type { ChatErrorInfo } from '../types/workbench';
+import { fallbackErrorClass } from './chatRetry';
+
+export type StreamEvent = {
+  id?: string;
+  type: string;
+  phase?: {
+    phase_id?: string;
+    message?: string;
+    step_index?: number;
+    total_steps?: number;
+    progress?: number;
+  };
+  status?: { message?: string; intent?: string };
+  delta?: string;
+  error?: string;
+  error_info?: {
+    user_message?: string;
+    code?: string;
+    class?: string;
+    phase_id?: string;
+    upstream?: string;
+    request_id?: string;
+    session_id?: string;
+    workspace_id?: string;
+    actions?: string[];
+  };
+  done?: { session_id?: string; duration_ms?: number };
+};
+
+type ErrorAction = ChatErrorInfo['actions'][number];
+
+const VALID_ACTIONS: readonly ErrorAction[] = ['retry', 'continue', 'restart'];
+
+function isErrorClass(value: unknown): value is ChatErrorInfo['class'] {
+  return (
+    value === 'transient' ||
+    value === 'resumable' ||
+    value === 'fatal' ||
+    value === 'cancelled'
+  );
+}
+
+function defaultActionsForClass(cls: ChatErrorInfo['class']): ChatErrorInfo['actions'] {
+  switch (cls) {
+    case 'transient':
+      return ['retry'];
+    case 'resumable':
+      return ['continue', 'restart'];
+    case 'fatal':
+      return ['restart'];
+    case 'cancelled':
+      return ['retry'];
+    default: {
+      const _exhaustive: never = cls;
+      return _exhaustive;
+    }
+  }
+}
+
+function parseActions(raw?: string[]): ChatErrorInfo['actions'] {
+  if (!raw?.length) return [];
+  return raw.filter((a): a is ErrorAction => (VALID_ACTIONS as readonly string[]).includes(a));
+}
+
+function parseFrame(frame: string): StreamEvent | null {
+  if (!frame.trim()) return null;
+
+  let dataLine: string | undefined;
+  for (const line of frame.split('\n')) {
+    if (line.startsWith('data:')) {
+      dataLine = line.slice(5).trim();
+    }
+  }
+  if (!dataLine) return null;
+
+  return JSON.parse(dataLine) as StreamEvent;
+}
+
+export function parseSSEChunk(buffer: string): { events: StreamEvent[]; rest: string } {
+  const events: StreamEvent[] = [];
+  if (!buffer) return { events, rest: '' };
+
+  const frames = buffer.split('\n\n');
+  const hasTrailingDelimiter = buffer.endsWith('\n\n');
+  const processCount = hasTrailingDelimiter ? frames.length : Math.max(0, frames.length - 1);
+
+  for (let i = 0; i < processCount; i++) {
+    const ev = parseFrame(frames[i]);
+    if (ev) events.push(ev);
+  }
+
+  const rest = hasTrailingDelimiter ? '' : (frames[frames.length - 1] ?? '');
+  return { events, rest };
+}
+
+export async function streamChat(
+  body: Record<string, unknown>,
+  handlers: {
+    onEvent: (ev: StreamEvent) => void;
+    onRequestId?: (id: string) => void;
+  },
+  signal?: AbortSignal,
+): Promise<void> {
+  const resp = await fetch('/api/v1/chat/stream', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json', Accept: 'text/event-stream' },
+    body: JSON.stringify(body),
+    signal,
+  });
+  const rid = resp.headers.get('X-Request-Id') || resp.headers.get('x-request-id');
+  if (rid) handlers.onRequestId?.(rid);
+  if (!resp.ok || !resp.body) {
+    throw Object.assign(new Error(`HTTP ${resp.status}`), {
+      httpStatus: resp.status,
+      requestId: rid,
+    });
+  }
+  const reader = resp.body.getReader();
+  const decoder = new TextDecoder();
+  let buf = '';
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) break;
+    buf += decoder.decode(value, { stream: true });
+    const parsed = parseSSEChunk(buf);
+    buf = parsed.rest;
+    for (const ev of parsed.events) handlers.onEvent(ev);
+  }
+}
+
+export function mapErrorInfo(ev: StreamEvent): ChatErrorInfo {
+  const ei = ev.error_info ?? {};
+  const userMessage = ei.user_message ?? ev.error ?? '发生未知错误';
+  const code = ei.code ?? 'UNKNOWN_ERROR';
+
+  const cls: ChatErrorInfo['class'] = isErrorClass(ei.class)
+    ? ei.class
+    : fallbackErrorClass({ workspaceId: ei.workspace_id });
+
+  let actions = parseActions(ei.actions);
+  if (!actions.length) {
+    actions = defaultActionsForClass(cls);
+  }
+
+  return {
+    userMessage,
+    code,
+    class: cls,
+    phaseId: ei.phase_id,
+    upstream: ei.upstream,
+    requestId: ei.request_id,
+    sessionId: ei.session_id,
+    workspaceId: ei.workspace_id,
+    actions,
+  };
+}
diff --git a/web/src/types/workbench.ts b/web/src/types/workbench.ts
index bd133372..bc9f4ec8 100644
--- a/web/src/types/workbench.ts
+++ b/web/src/types/workbench.ts
@@ -5,6 +5,8 @@ export type StageKey = 'V0.1' | 'V0.5' | 'V1.0';
 
 export interface ProjectSession {
   sessionId: string;
+  /** 会话归属用户：每人与智能体私聊，互不可见 */
+  userId: number;
   projectId: number;
   title: string;
   deviceType: string;
@@ -73,6 +75,26 @@ export interface InteractiveCardData {
   resolvedBy?: string;
 }
 
+export type AssistantMessageStatus =
+  | 'pending'
+  | 'streaming_status'
+  | 'auto_retrying'
+  | 'completed'
+  | 'failed'
+  | 'cancelled';
+
+export interface ChatErrorInfo {
+  userMessage: string;
+  code: string;
+  class: 'transient' | 'resumable' | 'fatal' | 'cancelled';
+  phaseId?: string;
+  upstream?: string;
+  requestId?: string;
+  sessionId?: string;
+  workspaceId?: string;
+  actions: Array<'retry' | 'continue' | 'restart'>;
+}
+
 export interface ChatMessage {
   id: string;
   sessionId: string;
@@ -90,6 +112,11 @@ export interface ChatMessage {
   phaseEvents?: PhaseEvent[];
   recommendedCases?: RecommendedCase[];
   interactiveCard?: InteractiveCardData;
+  status?: AssistantMessageStatus;
+  livePhaseLabel?: string;
+  errorInfo?: ChatErrorInfo;
+  requestId?: string;
+  sourceUserMessageId?: string;
 }
 
 export type DeliverableCategory = 'workflow' | 'shared' | 'private';