Feature/ai post suggestions (#40)

* feat: first cut on ai suggestion system for title and summary

* feat: completion of titling/excerpt/slug-suggestion AI quick action

* feat: feeds use existing excerpts. also documentation.

---------

Co-authored-by: hugo <hugoms@me.com>

tests/engine/ai/analyzePost.test.ts

@@ -0,0 +1,184 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+// Mock the AI SDK generateText before importing OneShotTasks
+vi.mock('ai', () => ({
+  generateText: vi.fn(),
+}));
+
+// Mock i18n
+vi.mock('../../../src/main/shared/i18n', () => ({
+  resolveSupportedRenderLanguage: vi.fn((lang: string) => lang),
+  translateRender: vi.fn((_lang: string, key: string) => {
+    const prompts: Record<string, string> = {
+      'ai.postAnalysis.system': 'You are a blog editor assistant. Analyze the blog post and suggest improvements. Return JSON with "title", "excerpt", "slug". Respond in en.',
+      'ai.postAnalysis.user': 'Analyze this blog post.',
+    };
+    return prompts[key] || key;
+  }),
+}));
+
+import { OneShotTasks, type PostAnalysisResult } from '../../../src/main/engine/ai/tasks';
+import { generateText } from 'ai';
+
+const mockGenerateText = vi.mocked(generateText);
+
+function createMockDeps() {
+  const chatEngine = {
+    getSetting: vi.fn().mockResolvedValue(null),
+  } as any;
+
+  const providers = {
+    detectModelProvider: vi.fn().mockReturnValue('opencode'),
+    isProviderKeySet: vi.fn().mockReturnValue(true),
+    getOpencodeKey: vi.fn().mockReturnValue('test-key'),
+    getMistralKey: vi.fn().mockReturnValue(null),
+    resolveModel: vi.fn().mockReturnValue('mock-model'),
+    isOfflineMode: vi.fn().mockReturnValue(false),
+    isOllamaModel: vi.fn().mockReturnValue(false),
+    isLmstudioModel: vi.fn().mockReturnValue(false),
+    getFirstKnownLocalModelId: vi.fn().mockReturnValue(null),
+  } as any;
+
+  const mediaEngine = {} as any;
+
+  const postEngine = {
+    getPost: vi.fn(),
+  } as any;
+
+  return { chatEngine, providers, mediaEngine, postEngine };
+}
+
+describe('OneShotTasks.analyzePost', () => {
+  let deps: ReturnType<typeof createMockDeps>;
+  let tasks: OneShotTasks;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    deps = createMockDeps();
+    tasks = new OneShotTasks(deps.providers, deps.chatEngine, deps.mediaEngine, deps.postEngine);
+  });
+
+  it('returns title, excerpt, and slug from AI response', async () => {
+    deps.postEngine.getPost.mockResolvedValue({
+      id: 'post-1',
+      title: 'My Post',
+      slug: 'my-post',
+      excerpt: '',
+      content: 'This is the content of my blog post about testing.',
+      status: 'draft',
+    });
+
+    mockGenerateText.mockResolvedValue({
+      text: '{"title": "Better Title", "excerpt": "A concise summary of the post.", "slug": "better-title"}',
+    } as any);
+
+    const result: PostAnalysisResult = await tasks.analyzePost('post-1', 'en');
+
+    expect(result.success).toBe(true);
+    expect(result.title).toBe('Better Title');
+    expect(result.excerpt).toBe('A concise summary of the post.');
+    expect(result.slug).toBe('better-title');
+    expect(deps.postEngine.getPost).toHaveBeenCalledWith('post-1');
+  });
+
+  it('returns error when post is not found', async () => {
+    deps.postEngine.getPost.mockResolvedValue(null);
+
+    const result = await tasks.analyzePost('nonexistent', 'en');
+
+    expect(result.success).toBe(false);
+    expect(result.error).toBe('Post not found');
+  });
+
+  it('returns error when post has no content', async () => {
+    deps.postEngine.getPost.mockResolvedValue({
+      id: 'post-1',
+      title: '',
+      slug: 'post-1',
+      content: '',
+      status: 'draft',
+    });
+
+    const result = await tasks.analyzePost('post-1', 'en');
+
+    expect(result.success).toBe(false);
+    expect(result.error).toBe('Post has no content to analyze');
+  });
+
+  it('returns error when no API key is configured', async () => {
+    deps.providers.getOpencodeKey.mockReturnValue(null);
+    deps.providers.getMistralKey.mockReturnValue(null);
+    deps.providers.isProviderKeySet.mockReturnValue(false);
+
+    deps.postEngine.getPost.mockResolvedValue({
+      id: 'post-1',
+      title: 'Test',
+      content: 'Content here',
+      status: 'draft',
+    });
+
+    const result = await tasks.analyzePost('post-1', 'en');
+
+    expect(result.success).toBe(false);
+    expect(result.error).toContain('API key');
+  });
+
+  it('sanitizes slug to lowercase with hyphens only', async () => {
+    deps.postEngine.getPost.mockResolvedValue({
+      id: 'post-1',
+      title: 'Test',
+      slug: 'test',
+      content: 'Content here',
+      status: 'draft',
+    });
+
+    mockGenerateText.mockResolvedValue({
+      text: '{"title": "New Title", "excerpt": "Summary text.", "slug": "Some Weird Slug!"}',
+    } as any);
+
+    const result = await tasks.analyzePost('post-1', 'en');
+
+    expect(result.success).toBe(true);
+    expect(result.slug).toMatch(/^[a-z0-9-]+$/);
+  });
+
+  it('handles AI response parse errors gracefully', async () => {
+    deps.postEngine.getPost.mockResolvedValue({
+      id: 'post-1',
+      title: 'Test',
+      content: 'Content',
+      status: 'draft',
+    });
+
+    mockGenerateText.mockResolvedValue({
+      text: 'not valid json at all',
+    } as any);
+
+    const result = await tasks.analyzePost('post-1', 'en');
+
+    expect(result.success).toBe(false);
+    expect(result.error).toBe('Invalid response format from AI');
+  });
+
+  it('uses title model when configured', async () => {
+    deps.chatEngine.getSetting.mockResolvedValue('custom-model-id');
+    deps.providers.detectModelProvider.mockReturnValue('opencode');
+    deps.providers.isProviderKeySet.mockReturnValue(true);
+
+    deps.postEngine.getPost.mockResolvedValue({
+      id: 'post-1',
+      title: 'Test',
+      content: 'Content',
+      status: 'draft',
+    });
+
+    mockGenerateText.mockResolvedValue({
+      text: '{"title": "T", "excerpt": "E", "slug": "t"}',
+    } as any);
+
+    await tasks.analyzePost('post-1', 'en');
+
+    expect(deps.chatEngine.getSetting).toHaveBeenCalledWith('chat_title_model');
+    expect(deps.providers.resolveModel).toHaveBeenCalledWith('custom-model-id');
+  });
+});