fix(F148): background context_briefing renders as card instead of raw JSON

packages/web/src/hooks/__tests__/useSocket-background.test.ts

@@ -496,6 +496,65 @@ describe('background thread socket handling', () => {
     });
   });
 
+  describe('F148: context briefing system_info', () => {
+    it('stores the briefing card message instead of a raw JSON system bubble', () => {
+      const now = Date.now();
+
+      simulateBackgroundMessage({
+        type: 'system_info',
+        catId: 'opus',
+        threadId: 'thread-bg',
+        content: JSON.stringify({
+          type: 'context_briefing',
+          messageId: 'briefing-msg-1',
+          storedMessage: {
+            id: 'briefing-msg-1',
+            content: '看到 13 条 · 省略 8 条 · 锚点 3 条 · 记忆 5 sessions · 证据 3 条',
+            origin: 'briefing',
+            timestamp: now,
+            extra: {
+              rich: {
+                v: 1,
+                blocks: [
+                  {
+                    id: 'briefing-1',
+                    kind: 'card',
+                    v: 1,
+                    title: '看到 13 条 · 省略 8 条 · 锚点 3 条 · 记忆 5 sessions · 证据 3 条',
+                    tone: 'info',
+                  },
+                ],
+              },
+            },
+          },
+        }),
+        timestamp: now,
+      });
+
+      const ts = useChatStore.getState().getThreadState('thread-bg');
+      expect(ts.messages).toEqual([
+        expect.objectContaining({
+          id: 'briefing-msg-1',
+          type: 'system',
+          content: '看到 13 条 · 省略 8 条 · 锚点 3 条 · 记忆 5 sessions · 证据 3 条',
+          origin: 'briefing',
+          extra: {
+            rich: {
+              v: 1,
+              blocks: [
+                expect.objectContaining({
+                  id: 'briefing-1',
+                  kind: 'card',
+                  title: '看到 13 条 · 省略 8 条 · 锚点 3 条 · 记忆 5 sessions · 证据 3 条',
+                }),
+              ],
+            },
+          },
+        }),
+      ]);
+    });
+  });
+
   describe('regression: background stream chunk merging', () => {
     it('merges text chunks from same cat/thread into one assistant message', () => {
       const now = Date.now();

packages/web/src/hooks/useSocket-background-system-info.ts

@@ -89,6 +89,21 @@ export function consumeBackgroundSystemInfo(
         options.store.setThreadMessageUsage(msg.threadId, existingRef.id, parsed.usage);
       }
       consumed = true;
+    } else if (parsed?.type === 'context_briefing') {
+      const storedMessage = parsed.storedMessage as
+        | { id: string; content: string; origin: string; timestamp: number; extra?: Record<string, unknown> }
+        | undefined;
+      if (storedMessage?.id) {
+        options.store.addMessageToThread(msg.threadId, {
+          id: storedMessage.id,
+          type: 'system',
+          content: storedMessage.content ?? '',
+          origin: (storedMessage.origin as 'briefing') ?? 'briefing',
+          timestamp: storedMessage.timestamp ?? Date.now(),
+          ...(storedMessage.extra ? { extra: storedMessage.extra } : {}),
+        });
+      }
+      consumed = true;
     } else if (parsed?.type === 'context_health') {
       const targetCatId = parsed.catId ?? msg.catId;
       options.store.setThreadCatInvocation(msg.threadId, targetCatId, {