docs: initialize project

Refactoring auto-mode-service.ts (5k+ lines) into smaller, focused services with clear boundaries.

.planning/PROJECT.md

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+# AutoModeService Refactoring
+
+## What This Is
+
+A comprehensive refactoring of the `auto-mode-service.ts` file (5k+ lines) into smaller, focused services with clear boundaries. This is an architectural cleanup of accumulated technical debt from rapid development, breaking the "god object" anti-pattern into maintainable, debuggable modules.
+
+## Core Value
+
+All existing auto-mode functionality continues working — features execute, pipelines flow, merges complete — while the codebase becomes maintainable.
+
+## Requirements
+
+### Validated
+
+<!-- Existing functionality that must be preserved -->
+
+- ✓ Single feature execution with AI agent — existing
+- ✓ Concurrent execution with configurable limits — existing
+- ✓ Pipeline orchestration (backlog → in-progress → approval → verified) — existing
+- ✓ Git worktree isolation per feature — existing
+- ✓ Automatic merging of completed work — existing
+- ✓ Custom pipeline support — existing
+- ✓ Test runner integration — existing
+- ✓ Event streaming to frontend — existing
+
+### Active
+
+<!-- Refactoring goals -->
+
+- [ ] No service file exceeds ~500 lines
+- [ ] Each service has single, clear responsibility
+- [ ] Service boundaries make debugging obvious
+- [ ] Changes to one service don't risk breaking unrelated features
+- [ ] Test coverage for critical paths
+
+### Out of Scope
+
+- New auto-mode features — this is cleanup, not enhancement
+- UI changes — backend refactor only
+- Performance optimization — maintain current performance, don't optimize
+- Other service refactoring — focus on auto-mode-service.ts only
+
+## Context
+
+**Current state:** `apps/server/src/services/auto-mode-service.ts` is ~5700 lines handling:
+
+- Worktree management (create, cleanup, track)
+- Agent/task execution coordination
+- Concurrency control and queue management
+- Pipeline state machine (column transitions)
+- Merge handling and conflict resolution
+- Event emission for real-time updates
+
+**Technical environment:**
+
+- Express 5 backend, TypeScript
+- Event-driven architecture via EventEmitter
+- WebSocket streaming to React frontend
+- Git worktrees via @automaker/git-utils
+- Minimal existing test coverage
+
+**Codebase analysis:** See `.planning/codebase/` for full architecture, conventions, and existing patterns.
+
+## Constraints
+
+- **Breaking changes**: Acceptable — other parts of the app can be updated to match new service interfaces
+- **Test coverage**: Currently minimal — must add tests during refactoring to catch regressions
+- **Incremental approach**: Required — can't do big-bang rewrite with everything critical
+- **Existing patterns**: Follow conventions in `.planning/codebase/CONVENTIONS.md`
+
+## Key Decisions
+
+| Decision                  | Rationale                                           | Outcome   |
+| ------------------------- | --------------------------------------------------- | --------- |
+| Accept breaking changes   | Allows cleaner interfaces, worth the migration cost | — Pending |
+| Add tests during refactor | No existing safety net, need to build one           | — Pending |
+| Incremental extraction    | Everything is critical, can't break it all at once  | — Pending |
+
+---
+
+_Last updated: 2026-01-27 after initialization_