feat: macOS menu bar app (Wails v3 + Svelte 5 + Tailwind 4)

[amargiovanni]

Fair warning: This is a deep architectural change that nobody asked for. I got excited and built it. If this is too much, too soon, or just not the direction you want — feel free to tell me to go pound sand. I'd rather discuss it in an issue first than force something unwanted. No hard feelings either way.

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Summary

• New macOS menu bar app (lazyagent-app) using Wails v3 + Svelte 5 + Tailwind 4, living alongside the existing TUI
• Core library extraction (internal/core/) — shared session management, file watcher, activity state machine, config system, and helpers used by both TUI and app
• TUI refactored to import from internal/core/ instead of local implementations — zero behavior changes, same binary size
• Both entry points build from the same go.mod: go build ./cmd/tui/ (5MB) and go build ./cmd/app/ (18MB)

What the menu bar app does

• System tray icon (no Dock icon) with click-to-toggle frameless floating panel
• Real-time session list with SVG sparklines, activity badges, token/cost display
• Detail panel with model, branch, messages, conversation preview, recent tools
• Keyboard shortcuts: j/k navigate, / search, f filter, +/- time window, r refresh
• FSEvents file watcher + 1s activity tick + 30s full reload (same strategy as TUI)
• Catppuccin Mocha dark theme via Tailwind 4 @theme
• Right-click context menu: Show Panel, Refresh Now, Quit

Architecture

cmd/tui/          → TUI entry point (unchanged behavior)
cmd/app/          → Wails v3 macOS app (new)
internal/core/    → Shared: watcher, activity, session, config, helpers (extracted)
internal/ui/      → TUI-only rendering (now thin, imports core)
internal/assets/  → Embedded frontend dist (go:embed)
frontend/         → Svelte 5 + Tailwind 4 (new)

Code quality fixes included

After the initial implementation, I ran a three-way review (reuse, quality, efficiency) and fixed:

• CRITICAL: Added sync.RWMutex to SessionManager — prevents data races between the background watchLoop goroutine and Wails IPC handler goroutines
• HIGH: watchLoop now selects on ctx.Done() for clean goroutine shutdown
• MEDIUM: 1s ticker only emits sessions:updated when activity states actually changed (was unconditional)
• MEDIUM: Extracted EffectiveCost() helper — cost fallback pattern was duplicated 3x
• MEDIUM: Extracted buildSessionItem() — SessionItem construction was copy-pasted between GetSessions and GetSessionDetail
• MEDIUM: OpenInEditor now checks Config.Editor before falling back to $VISUAL/$EDITOR
• LOW: Window-minutes bounds centralized in core.SetWindowMinutes() via Clamp() — was magic numbers in 3 files
• LOW: Sparkline SVG coordinate math unified into single $derived

Intentionally left out of scope (and why)

Item	Reason
formatTokens/formatCost duplicated in Go and TypeScript	Both are display formatters. Pre-formatting server-side would couple presentation to backend. Acceptable duplication at the system boundary.
Activity filter list hardcoded in both Go and Svelte	Matches AllActivities in Go. Generating from bindings would add build complexity for a list that changes ~never.
.catch(() => {}) on frontend IPC calls	These are fire-and-forget UI actions (filter, search, window adjust). Errors are non-fatal — next tick retries via the event loop.
Events.On listener not cleaned up in onDestroy	Single-page app in a single window that never unmounts. No practical leak.
GetActiveCount binding unused by frontend	Kept for the planned dynamic tray label feature (show active count in menu bar).
Stale ago values in tool list	Pre-computed server-side when detail is fetched. Refreshes on next sessions:updated event. Acceptable staleness for a monitoring tool.
GetConfig re-reads from disk every call	Called rarely (on demand). Caching would add complexity for no measurable gain.
JSONL incremental parsing / mtime caching	DiscoverSessions re-parses all files on reload. For typical session counts (5-20) this is fast enough. Worth optimizing later if session counts grow.
git rev-parse cache promotion to SessionManager	Per-invocation cache in DiscoverSessions is rebuilt every reload. Fine for now, could be promoted if git subprocess cost becomes noticeable.

Test plan

• go vet ./... passes clean
• go build ./cmd/tui/ produces working TUI (verify sparkline, cost, spinner, filter, search, open)
• go build ./cmd/app/ produces 18MB arm64 binary
• App starts, tray icon appears, no Dock icon
• Click tray → panel opens with real sessions
• Click session → detail panel with sparkline, model, tokens, conversation
• Keyboard shortcuts work (j/k, /, f, +/-, r, esc)
• Right-click tray → context menu works
• Panel closes on focus lost
• go build . (root alias) still works

🤖 Generated with Claude Code

[nahime0]

@amargiovanni I'd prefer having a single binary with flags for the different modes rather than two separate binaries. I've refactored the branch so that:

• lazyagent → launches the TUI (default)
• lazyagent --tray → launches the macOS menu bar app (auto-detaches)
• lazyagent --tui --tray → launches both simultaneously