feat(v0.6): per-project detail view — branch/worktrees + active sessions

Clicking a project's name opens an in-app detail view (back button returns to
the grid) with:
- header: name, path, branch, dirty
- Branch / Worktrees: each `git worktree list` entry (branch or detached@head,
  main/current/locked/prunable tags, path) — a single-worktree repo shows its
  branch; a multi-worktree repo shows them all
- Active sessions (N): detailed rows (status, devices watching, started-ago)
  with Open + Kill
- the Claude/Codex/VS Code launcher row

Backend: src/http/worktrees.ts (parseWorktrees pure + listWorktrees via
execFile, no shell, best-effort); buildProjectDetail(cfg, path, liveSessions)
in projects.ts (validates absolute existing dir, reuses branch/dirty/session
helpers, uncached — detail is on-demand and wants fresh state); read-only
GET /projects/detail?path= (no Origin guard, like /projects; 400 missing /
404 invalid). Types: WorktreeInfo, ProjectDetail.

Frontend: detail view + navigation in projects.ts (grid<->detail), project
name becomes a link, Kill via DELETE /live-sessions/:id.

Tests +21 (452 total): worktree parser, buildProjectDetail (validation,
non-git, session merge, real git-init worktree), renderProjectDetail.
worktrees.ts 100% / projects.ts 93.8% cov. Verified in-browser: opened a
Claude session, then the detail showed its branch+worktree and the live
session with Open/Kill.

test/projects-panel.test.ts

@@ -21,8 +21,16 @@ class FakeTerminal {
 vi.mock('@xterm/xterm', () => ({ Terminal: FakeTerminal }))
 
 // Dynamic import AFTER mock declaration so the factory is in place.
-const { filterProjects, sortProjects, getFavs, saveFavs, toggleFav, normalizeProject, makeProjectCard } =
-  await import('../public/projects.js')
+const {
+  filterProjects,
+  sortProjects,
+  getFavs,
+  saveFavs,
+  toggleFav,
+  normalizeProject,
+  makeProjectCard,
+  renderProjectDetail,
+} = await import('../public/projects.js')
 
 /* ── Helpers ───────────────────────────────────────────────────────────────── */
 
@@ -352,4 +360,109 @@ describe('makeProjectCard — launcher row', () => {
     const card = makeProjectCard(p, new Set(), noopHooks(), () => {})
     expect(card.querySelector('.proj-launch-claude .proj-launch-badge')?.textContent).toBe('2')
   })
+
+  it('makes the name a detail link only when onOpenDetail is given', () => {
+    const onOpenDetail = vi.fn()
+    const card = makeProjectCard(makeProject({ path: '/p/r' }), new Set(), noopHooks(), () => {}, onOpenDetail)
+    const name = card.querySelector('.proj-name') as HTMLElement
+    expect(name.classList.contains('proj-name-link')).toBe(true)
+    name.click()
+    expect(onOpenDetail).toHaveBeenCalledWith('/p/r')
+
+    const plain = makeProjectCard(makeProject(), new Set(), noopHooks(), () => {})
+    expect(plain.querySelector('.proj-name')!.classList.contains('proj-name-link')).toBe(false)
+  })
+})
+
+/* ── renderProjectDetail (branch/worktrees + active sessions) ───────────────── */
+
+describe('renderProjectDetail', () => {
+  const hooks = () => ({ onOpenProject: vi.fn(), onEnterSession: vi.fn() })
+  const cbs = () => ({ onBack: vi.fn(), onKill: vi.fn() })
+
+  function detail(over: Partial<import('../src/types.js').ProjectDetail> = {}) {
+    return {
+      name: 'repo',
+      path: '/p/repo',
+      isGit: true,
+      branch: 'main',
+      worktrees: [],
+      sessions: [],
+      ...over,
+    }
+  }
+
+  it('renders "Project not found" + working Back for a null detail', () => {
+    const cb = cbs()
+    const root = renderProjectDetail(null, hooks(), cb)
+    expect(root.textContent).toContain('Project not found')
+    ;(root.querySelector('.proj-back') as HTMLButtonElement).click()
+    expect(cb.onBack).toHaveBeenCalled()
+  })
+
+  it('shows the header name, path, and branch', () => {
+    const root = renderProjectDetail(detail(), hooks(), cbs())
+    expect(root.querySelector('.proj-detail-name')?.textContent).toBe('repo')
+    expect(root.querySelector('.proj-detail-path')?.textContent).toBe('/p/repo')
+    expect(root.querySelector('.proj-branch')?.textContent).toBe('main')
+  })
+
+  it('lists worktrees with branch, tags, and path', () => {
+    const root = renderProjectDetail(
+      detail({
+        worktrees: [
+          { path: '/p/repo', branch: 'main', head: 'abc12345', isMain: true, isCurrent: true },
+          { path: '/p/wt/feat', branch: 'feature/x', head: 'def67890', isMain: false, isCurrent: false },
+        ],
+      }),
+      hooks(),
+      cbs(),
+    )
+    const rows = root.querySelectorAll('.proj-wt-row')
+    expect(rows).toHaveLength(2)
+    expect(rows[0]?.querySelector('.proj-wt-branch')?.textContent).toBe('main')
+    expect(rows[0]?.querySelector('.proj-wt-tag-current')).not.toBeNull()
+    expect(rows[1]?.querySelector('.proj-wt-branch')?.textContent).toBe('feature/x')
+  })
+
+  it('renders detached worktrees as "detached @ head"', () => {
+    const root = renderProjectDetail(
+      detail({ worktrees: [{ path: '/p/repo', head: 'deadbeef', isMain: true, isCurrent: true }] }),
+      hooks(),
+      cbs(),
+    )
+    expect(root.querySelector('.proj-wt-branch')?.textContent).toBe('detached @ deadbeef')
+  })
+
+  it('lists active sessions with Open + Kill wired, ignoring exited ones', () => {
+    const h = hooks()
+    const cb = cbs()
+    const root = renderProjectDetail(
+      detail({
+        sessions: [
+          { id: 's1', title: 'claude', status: 'working', clientCount: 2, createdAt: 1, exited: false },
+          { id: 'gone', status: 'idle', clientCount: 0, createdAt: 1, exited: true },
+        ],
+      }),
+      h,
+      cb,
+    )
+    const rows = root.querySelectorAll('.proj-dsession')
+    expect(rows).toHaveLength(1)
+    ;(rows[0]!.querySelector('.proj-dsession-open') as HTMLButtonElement).click()
+    expect(h.onEnterSession).toHaveBeenCalledWith('s1')
+    ;(rows[0]!.querySelector('.proj-dsession-kill') as HTMLButtonElement).click()
+    expect(cb.onKill).toHaveBeenCalledWith('s1')
+  })
+
+  it('shows an empty-state when no sessions are running, plus the launcher row', () => {
+    const root = renderProjectDetail(detail(), hooks(), cbs())
+    expect(root.textContent).toContain('No running sessions')
+    expect(root.querySelectorAll('.proj-launch')).toHaveLength(3)
+  })
+
+  it('flags a non-git directory', () => {
+    const root = renderProjectDetail(detail({ isGit: false, branch: undefined }), hooks(), cbs())
+    expect(root.textContent).toContain('Not a git repository')
+  })
 })