fix: switch to processing status when receiving response tokens from LLM

src/hooks/useStreamProcessor.test.ts

@@ -0,0 +1,92 @@
+import { act, renderHook } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+
+vi.mock('../agent/core/AgentCore', () => ({
+  AgentCore: {
+    instance: vi.fn()
+  }
+}));
+
+vi.mock('../utils/chatMessageUtils', () => ({
+  createStreamingMessage: () => ({
+    id: 'streaming-message',
+    role: 'assistant',
+    content: '<span class="processing-wave">Thinking...</span> click here to abort.',
+    isStreaming: true,
+    tokenCount: 0
+  }),
+  createMessage: (role: 'user' | 'assistant', content: string) => ({
+    id: `${role}-message`,
+    role,
+    content
+  })
+}));
+
+import { AgentCore } from '../agent/core/AgentCore';
+import { useStreamProcessor } from './useStreamProcessor';
+import type { ChatMessage } from '../types/projectTypes';
+
+const flushMicrotasks = async (): Promise<void> => {
+  await Promise.resolve();
+  await Promise.resolve();
+};
+
+describe('useStreamProcessor', () => {
+  it('switches from Thinking to Processing after the first text token arrives', async () => {
+    let releaseDone!: () => void;
+    const doneGate = new Promise<void>((resolve) => {
+      releaseDone = resolve;
+    });
+
+    vi.spyOn(AgentCore, 'instance').mockReturnValue({
+      processUserInput: async function* () {
+        yield { type: 'text', content: 'Hello' };
+        await doneGate;
+        yield { type: 'done', content: '' };
+      }
+    } as unknown as AgentCore);
+
+    const messages = new Map<string, ChatMessage>();
+    const processingChanges: boolean[] = [];
+
+    const { result } = renderHook(() => useStreamProcessor({
+      onMessageAdd: (message) => {
+        messages.set(message.id, message);
+      },
+      onMessageUpdate: (messageId, updater) => {
+        const current = messages.get(messageId);
+        if (!current) {
+          throw new Error(`Missing message ${messageId}`);
+        }
+        messages.set(messageId, updater(current));
+      },
+      onMessageRemove: (messageId) => {
+        messages.delete(messageId);
+      },
+      onProcessingChange: (isProcessing) => {
+        processingChanges.push(isProcessing);
+      }
+    }));
+
+    let responsePromise!: Promise<string>;
+    await act(async () => {
+      responsePromise = result.current.processStream('test prompt');
+      await flushMicrotasks();
+    });
+
+    const streamingMessage = [...messages.values()][0];
+    expect(streamingMessage).toBeDefined();
+    expect(streamingMessage.content).toContain('<span class="processing-wave">Processing...</span>');
+    expect(streamingMessage.content).toContain('1 tokens received.');
+    expect(streamingMessage.content).toContain('click here to abort.');
+    expect(streamingMessage.tokenCount).toBe(1);
+    expect(processingChanges).toContain(true);
+
+    await act(async () => {
+      releaseDone();
+      await responsePromise;
+    });
+
+    expect(processingChanges.at(-1)).toBe(false);
+  });
+});