# Git, Process, and Logging Modules

Three infrastructure modules supporting agent execution.

## Git Module (`src/git/`)

Manages git worktrees for isolated agent workspaces.

### Architecture
- **Port**: `WorktreeManager` interface
- **Adapter**: `SimpleGitWorktreeManager` using simple-git library

### WorktreeManager Methods

| Method | Purpose |
|--------|---------|
| `create(id, branch, baseBranch?)` | Create worktree with new branch (default base: 'main') |
| `remove(id)` | Clean up worktree directory |
| `list()` | All worktrees including main |
| `get(id)` | Specific worktree by ID |
| `diff(id)` | Changed files vs HEAD |
| `merge(id, targetBranch)` | Merge worktree branch into target |

### Worktree Storage
Worktrees stored in `.cw-worktrees/` subdirectory of the repo. Each agent gets a worktree at `.cw-worktrees/agent/<alias>/`.

### Merge Flow
1. Check out target branch
2. `git merge <source> --no-edit`
3. On success: emit `worktree:merged`
4. On conflict: `git merge --abort`, emit `worktree:conflict` with conflicting file list
5. Restore original branch

### BranchManager (`src/git/branch-manager.ts`)
- **Port**: `BranchManager` interface
- **Adapter**: `SimpleGitBranchManager` using simple-git

| Method | Purpose |
|--------|---------|
| `ensureBranch(repoPath, branch, baseBranch)` | Create branch from base if it doesn't exist (idempotent) |
| `mergeBranch(repoPath, source, target)` | Merge via ephemeral worktree, returns conflict info |
| `diffBranches(repoPath, base, head)` | Three-dot diff between branches |
| `deleteBranch(repoPath, branch)` | Delete local branch (no-op if missing) |
| `branchExists(repoPath, branch)` | Check local branches |
| `remoteBranchExists(repoPath, branch)` | Check remote tracking branches (`origin/<branch>`) |

`remoteBranchExists` is used by `registerProject` and `updateProject` to validate that a project's default branch actually exists in the cloned repository before saving.

### Project Clones
- `cloneProject(url, destPath)` — Simple git clone wrapper
- `ensureProjectClone(project, workspaceRoot)` — Idempotent: checks if clone exists, clones if not
- `getProjectCloneDir(name, id)` — Canonical path: `repos/<sanitized-name>-<id>/`

### Events Emitted
`worktree:created`, `worktree:removed`, `worktree:merged`, `worktree:conflict`

---

## Process Module (`src/process/`)

Spawns, tracks, and controls child processes.

### Classes

**ProcessRegistry** — In-memory metadata store:
- `register(info)`, `unregister(id)`, `get(id)`, `getAll()`, `getByPid(pid)`, `updateStatus(id, status)`

**ProcessManager** — Lifecycle management:

| Method | Purpose |
|--------|---------|
| `spawn(options)` | Spawn detached process (survives parent exit) |
| `stop(id)` | SIGTERM → wait 5s → SIGKILL |
| `stopAll()` | Stop all running processes in parallel |
| `restart(id)` | Stop + re-spawn with same options |
| `isRunning(id)` | Check with `process.kill(pid, 0)` |

### Spawn Details
- Uses `execa` with `detached: true`, `stdio: 'ignore'`
- Calls `subprocess.unref()` so parent can exit
- Exit handler updates registry and emits events

### Events Emitted
`process:spawned`, `process:stopped`, `process:crashed`

---

## Logger Module (`src/logger/`)

Structured logging via **pino**.

### Usage
```typescript
import { createModuleLogger } from './logger/index.js';
const log = createModuleLogger('my-module');
log.info({ key: 'value' }, 'message');
```

### Configuration
| Env Var | Effect |
|---------|--------|
| `CW_LOG_LEVEL` | Override log level |
| `CW_LOG_PRETTY` | Set to `'1'` for human-readable output |
| `NODE_ENV=development` | Default to 'debug' level |

### Output
- Default: JSON to stderr (fd 2)
- Pretty mode: pino-pretty to stdout with colors and timestamps

---

## Logging Module (`src/logging/`)

File-based per-process output capture (separate from pino).

### Classes

**LogManager** — Directory management:
- Base dir: `~/.cw/logs/`
- Structure: `{processId}/stdout.log`, `{processId}/stderr.log`
- `cleanOldLogs(retainDays)` — removes old directories by mtime

**ProcessLogWriter** — File I/O with timestamps:
- `open()` — create directories and append-mode WriteStreams
- `writeStdout(data)` / `writeStderr(data)` — prefix each line with `[YYYY-MM-DD HH:mm:ss.SSS]`
- Handles backpressure (waits for drain event)
- Emits `log:entry` event via EventBus

### Factory
```typescript
import { createLogger } from './logging/index.js';
const writer = createLogger(processId, eventBus);
await writer.open();
await writer.writeStdout('output data');
await writer.close();
```