voicepaste/AGENTS.md

# AGENTS.md — VoicePaste

## Project Overview

VoicePaste: phone as microphone via browser → LAN WebSocket → Go server → Doubao ASR → real-time preview on phone → auto-paste to computer's focused app. Single Go binary with embedded frontend.

## Tech Stack

- **Backend**: Go 1.25+, Fiber v3, fasthttp/websocket, CGO required (robotgo + clipboard)
- **Frontend**: React 19, TypeScript, Zustand, Vite 7, Tailwind CSS v4, Biome 2, bun (package manager + runtime)
- **Tooling**: Taskfile (not Make), mise (Go + bun + task)
- **ASR**: Doubao Seed-ASR-2.0 via custom binary WebSocket protocol

## Build & Run Commands

```bash
# Install mise tools (go, bun, task)
mise install

# Build everything (frontend + Go binary → dist/)
task

# Build frontend only
task build:frontend

# Run (build + execute)
task run

# Dev mode (go run, skips frontend build)
task dev

# Clean all artifacts
task clean

# Tidy Go modules
task tidy
```

### Frontend (run from `web/`)

```bash
bun install              # Install deps
bun run build            # Vite production build
bun run dev              # Vite dev server
bun run lint             # Biome check (lint + format)
bun run lint:fix         # Biome check --write (auto-fix)
bun run typecheck        # tsc --noEmit
```

### Go

```bash
go vet ./...             # Lint
go build -o dist/voicepaste .  # Build (add .exe on Windows)
```

No test suite exists yet. No `go test` targets.

## Project Structure

```
main.go                     # Entry point, embed.FS, TLS init, server startup
internal/
  config/config.go          # YAML + env var config, fsnotify hot-reload, atomic global
  server/server.go          # Fiber v3 HTTPS server, static files from embed.FS
  server/net.go             # LAN IP detection
  tls/tls.go                # AnyIP cert download/cache + self-signed fallback
  tls/generate.go           # Self-signed cert generation
  ws/protocol.go            # JSON message types (start/stop/paste/partial/final/pasted/error)
  ws/handler.go             # WS upgrade, token auth, session lifecycle, text accumulation, paste
  asr/protocol.go           # Doubao binary protocol codec (4-byte header, gzip)
  asr/client.go             # WSS client to Doubao, audio streaming, result forwarding
  paste/paste.go            # clipboard.Write + robotgo key simulation (Ctrl+V / Cmd+V)
web/
  index.html                # HTML shell with React root
  vite.config.ts            # Vite config (React + Tailwind plugins)
  biome.json                # Biome config (lint, format, Tailwind class sorting)
  tsconfig.json             # TypeScript strict config (React JSX)
  src/
    main.tsx                # React entry point
    App.tsx                 # Root component: composes hooks + layout
    app.css                 # Tailwind imports, design tokens (@theme), keyframes
    stores/
      app-store.ts           # Zustand store: connection, recording, preview, history, toast
    hooks/
      useWebSocket.ts        # WS client hook: connect, reconnect, message dispatch
      useRecorder.ts         # Audio pipeline hook: WebVoiceProcessor (16kHz Int16 PCM capture)
    components/
      StatusBadge.tsx         # Connection status indicator
      PreviewBox.tsx          # Real-time transcription preview
      MicButton.tsx           # Push-to-talk button with animations
      HistoryList.tsx         # Transcription history with re-send
```

## Code Style — Go

### Imports
Group in stdlib → external → internal order, separated by blank lines:
```go
import (
    "fmt"
    "log/slog"

    "github.com/gofiber/fiber/v3"

    "github.com/imbytecat/voicepaste/internal/config"
)
```
Use aliases only to avoid collisions: `crypto_tls "crypto/tls"`, `vpTLS "...internal/tls"`, `wsMsg "...internal/ws"`.

### Logging
Use `log/slog` exclusively. Structured key-value pairs:
```go
slog.Info("message", "key", value)
slog.Error("failed to X", "err", err)
```
Per-connection loggers via `slog.With("remote", addr)`.

### Error Handling
- Always wrap with context: `fmt.Errorf("dial doubao: %w", err)`
- Return errors up; log at the boundary (main, handler entry)
- Never suppress errors silently. `slog.Warn` for non-fatal, `slog.Error` + exit/return for fatal
- Never use `as any`, `@ts-ignore`, or empty catch blocks

### Naming
- Package names: short, lowercase, single word (`asr`, `ws`, `paste`, `config`)
- Exported types: `PascalCase` with doc comments
- Unexported: `camelCase`
- Constants: `PascalCase` for exported, `camelCase` for unexported
- Acronyms stay uppercase: `ASR`, `TLS`, `WS`, `URL`, `IP`

### Patterns
- `sync.Mutex` for shared state, `chan` for goroutine communication
- `atomic.Value` for hot-reloadable config
- Goroutine cleanup: `defer`, `sync.WaitGroup`, `closeCh chan struct{}`
- Fiber v3 middleware pattern for auth checks before WS upgrade

## Code Style — TypeScript (Frontend)

### Formatting (Biome)
- Indent: tabs
- Quotes: double quotes
- Semicolons: default (enabled)
- Organize imports: enabled via Biome assist

### TypeScript Config
- `strict: true`, `noUnusedLocals`, `noUnusedParameters`
- Target: ES2022, module: ESNext, bundler resolution
- DOM + DOM.Iterable libs

- React 19 with functional components and hooks
- Zustand for global state management (connection, recording, preview, history, toast)
- Custom hooks for imperative APIs: `useWebSocket`, `useRecorder`
- Zustand `getState()` in hooks/callbacks to avoid stale closures
- Pointer Events for touch/mouse (not touch + mouse separately)
- @picovoice/web-voice-processor for audio capture (16kHz Int16 PCM, WASM resampling)
- WebVoiceProcessor handles getUserMedia, AudioContext lifecycle, cross-browser compat
- WebSocket: binary for audio frames, JSON text for control messages
- Tailwind CSS v4 with `@theme` design tokens; minimal custom CSS (keyframes only)

## Language & Locale

- **UI text**: Chinese (中文) — this app is for family members
- **Git commits**: Chinese, conventional format: `feat:`, `fix:`, `chore:`, `refactor:`
- **Code comments**: English
- **Communication with user**: Chinese (中文)

## Key Constraints

- CGO is required (robotgo, clipboard) — no cross-compilation
- Token auth: read from `config.yaml`; empty = no auth. Never auto-generate tokens
- Frontend is embedded via `//go:embed all:web/dist` in `main.go`
- `embed` directive cannot use `../` paths — must be in the package referencing it
- Build output goes to `dist/` (gitignored)
- Frontend ignores (`node_modules`, `dist`) in `web/.gitignore`, not root
- Config file (`config.yaml`) is gitignored; `config.example.yaml` is committed
- `os.UserCacheDir()` for platform-correct cert cache paths
- robotgo paste: `KeyDown(modifier)` → delay → `KeyTap("v")` → delay → `KeyUp(modifier)`

## Hotwords (热词) Feature

Local hotword management for improved ASR accuracy on specific terms (names, technical vocabulary).

### Configuration

```yaml
doubao:
  hotwords:
    - 张三
    - 李四
    - VoicePaste
    - 人工智能
```

### Implementation

- Hotwords stored locally in `config.yaml` (not tied to cloud provider)
- `BuildHotwordsContext()` converts string array to Doubao API format:
  ```json
  {"hotwords":[{"word":"张三"},{"word":"李四"}]}
  ```
- Sent via `corpus.context` parameter in `FullClientRequest`
- Hot-reloadable: config changes apply to new connections
- Platform-agnostic design: easy to migrate to other ASR providers

### Doubao API Details

- Parameter: `request.corpus.context` (JSON string)
- Limits: 100 tokens (双向流式), 5000 tokens (流式输入)
- Priority: `context` hotwords > `boosting_table_id` (if both present)
- No weight support in `context` mode (unlike `boosting_table_id`)