fix: AI chat wikilinks — system prompt + integration tests

Root cause: buildContextSnapshot (the system prompt used when a note is
active — the common case) did NOT instruct the AI to use [[wikilinks]].
Only buildAgentSystemPrompt (the fallback when no context) had it.
So the AI almost never produced clickable wikilinks.

Fix: Add the [[Note Title]] wikilink instruction to
buildContextSnapshot's preamble.

The click handler chain was already correct (verified with new
integration tests): MarkdownContent → AiMessage → AiPanel →
notes.handleNavigateWikilink → findWikilinkTarget → handleSelectNote.

Tests added:
- Unit: buildContextSnapshot includes wikilink instruction
- Integration: clicking wikilinks in AiPanel calls onOpenNote
- Playwright: wikilink renders, click opens note in tab

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/AiPanel.test.tsx

@@ -4,10 +4,12 @@ import { AiPanel } from './AiPanel'
 import type { VaultEntry } from '../types'
 
 // Mock the hooks and utils to isolate component tests
+let mockMessages: ReturnType<typeof import('../hooks/useAiAgent').useAiAgent>['messages'] = []
+let mockStatus: ReturnType<typeof import('../hooks/useAiAgent').useAiAgent>['status'] = 'idle'
 vi.mock('../hooks/useAiAgent', () => ({
   useAiAgent: () => ({
-    messages: [],
-    status: 'idle',
+    messages: mockMessages,
+    status: mockStatus,
     sendMessage: vi.fn(),
     clearConversation: vi.fn(),
   }),
@@ -45,6 +47,11 @@ const makeEntry = (overrides: Partial<VaultEntry> = {}): VaultEntry => ({
 })
 
 describe('AiPanel', () => {
+  beforeEach(() => {
+    mockMessages = []
+    mockStatus = 'idle'
+  })
+
   it('renders panel with AI Chat header', () => {
     render(<AiPanel onClose={vi.fn()} vaultPath="/tmp/vault" />)
     expect(screen.getByText('AI Chat')).toBeTruthy()
@@ -162,4 +169,41 @@ describe('AiPanel', () => {
     fireEvent.keyDown(panel, { key: 'Escape' })
     expect(onClose).toHaveBeenCalledOnce()
   })
+
+  it('clicking a wikilink in AI response calls onOpenNote with the target', () => {
+    mockMessages = [{
+      userMessage: 'Tell me about notes',
+      actions: [],
+      response: 'Check out [[Build Laputa App]] for details.',
+      id: 'msg-1',
+    }]
+    const onOpenNote = vi.fn()
+    const { container } = render(
+      <AiPanel onClose={vi.fn()} vaultPath="/tmp/vault" onOpenNote={onOpenNote} />,
+    )
+    const wikilink = container.querySelector('.chat-wikilink')
+    expect(wikilink).toBeTruthy()
+    expect(wikilink!.textContent).toBe('Build Laputa App')
+    fireEvent.click(wikilink!)
+    expect(onOpenNote).toHaveBeenCalledWith('Build Laputa App')
+  })
+
+  it('renders wikilinks with special characters and clicking works', () => {
+    mockMessages = [{
+      userMessage: 'Tell me about meetings',
+      actions: [],
+      response: 'See [[Meeting — 2024/01/15]] and [[Pasta Carbonara]].',
+      id: 'msg-2',
+    }]
+    const onOpenNote = vi.fn()
+    const { container } = render(
+      <AiPanel onClose={vi.fn()} vaultPath="/tmp/vault" onOpenNote={onOpenNote} />,
+    )
+    const wikilinks = container.querySelectorAll('.chat-wikilink')
+    expect(wikilinks).toHaveLength(2)
+    fireEvent.click(wikilinks[0])
+    expect(onOpenNote).toHaveBeenCalledWith('Meeting — 2024/01/15')
+    fireEvent.click(wikilinks[1])
+    expect(onOpenNote).toHaveBeenCalledWith('Pasta Carbonara')
+  })
 })

src/utils/ai-context.test.ts

@@ -331,6 +331,12 @@ describe('buildContextSnapshot', () => {
     expect(json.noteList).toBeUndefined()
   })
 
+  it('includes wikilink instruction in preamble', () => {
+    const result = buildContextSnapshot({ activeEntry: active, allContent, entries })
+    expect(result).toContain('[[Note Title]]')
+    expect(result).toContain('wikilink')
+  })
+
   it('includes belongsTo and relatedTo in frontmatter', () => {
     const entryWithRels = makeEntry({
       path: '/vault/a.md', title: 'Alpha',

src/utils/ai-context.ts

@@ -152,6 +152,7 @@ export function buildContextSnapshot(params: ContextSnapshotParams): string {
     'You are an AI assistant integrated into Laputa, a personal knowledge management app.',
     'The user is viewing a specific note. Use the structured context below to answer questions accurately.',
     'You can also use MCP tools to search, read, create, or edit notes in the vault.',
+    'When you mention or reference a note by name, always use [[Note Title]] wikilink syntax so the user can click to open it.',
   ].join('\n')
 
   return `${preamble}\n\n## Context Snapshot\n\`\`\`json\n${JSON.stringify(snapshot, null, 2)}\n\`\`\``

tests/smoke/ai-chat-wikilink-clickable.spec.ts

@@ -48,15 +48,19 @@ test.describe('AI chat wikilink rendering', () => {
   })
 
   test('clicking a wikilink opens the note in a tab', async ({ page }) => {
-    const wikilink = page.locator('.chat-wikilink').first()
-    await expect(wikilink).toHaveText('Build Laputa App')
+    // Click the second wikilink ("Matteo Cellini") which is NOT already open in a tab
+    const wikilink = page.locator('.chat-wikilink').nth(1)
+    await expect(wikilink).toHaveText('Matteo Cellini')
+
+    // Verify "Matteo Cellini" is not yet in any tab
+    const tabsBefore = await page.locator('span.truncate:has-text("Matteo Cellini")').count()
 
     // Click the wikilink
     await wikilink.click()
     await page.waitForTimeout(500)
 
-    // Verify the note opened in a tab — the editor breadcrumb shows the active note title
-    const breadcrumb = page.locator('.app__editor span.truncate.font-medium', { hasText: 'Build Laputa App' })
-    await expect(breadcrumb).toBeVisible({ timeout: 3000 })
+    // Verify a new tab appeared with the note title
+    const tabsAfter = await page.locator('span.truncate:has-text("Matteo Cellini")').count()
+    expect(tabsAfter).toBeGreaterThan(tabsBefore)
   })
 })