# AGENTS.md — AI Coding Agent Instructions

> **For:** Claude Code, OpenAI Codex, Cursor, GitHub Copilot, Windsurf Cascade, and any AI coding agent.
> **Repo:** `learning_ai_notes` — NoteLett structured notes platform for humans and AI agents.
> **See also:** [`docs/PRD.md`](docs/PRD.md) for full product spec, [`docs/ROADMAP.md`](docs/ROADMAP.md) for implementation plan.

---

## 1. Project Identity

| Key | Value |
|-----|-------|
| **Product** | NoteLett |
| **Product ID** | `notelett` |
| **Bundle ID (iOS)** | `com.bytelyst.notelett` |
| **Bundle ID (Android)** | `com.notelett.app` |
| **Domain** | notelett.app |
| **Repo** | `learning_ai_notes` |
| **Ecosystem** | ByteLyst (shares platform-service with LysnrAI, MindLyst, ChronoMind, JarvisJr, NomGap, PeakPulse) |

## 2. Repo Layout

```
learning_ai_notes/
├── backend/                          # Fastify 5 + TypeScript ESM backend (port 4016)
│   ├── src/
│   │   ├── lib/
│   │   │   ├── config.ts             # Zod-validated env config
│   │   │   ├── product-config.ts     # Product identity from shared/product.json
│   │   │   ├── auth.ts               # JWT extraction helper
│   │   │   ├── request-context.ts    # getUserId(req), getRequestProductId(req)
│   │   │   ├── cosmos-init.ts        # Cosmos container registration
│   │   │   ├── datastore.ts          # @bytelyst/datastore provider (Cosmos or memory)
│   │   │   └── errors.ts             # Re-export from @bytelyst/errors
│   │   ├── modules/
│   │   │   ├── notes/                # Note CRUD (types, repository, routes, test)
│   │   │   ├── workspaces/           # Workspace CRUD (types, repository, routes, test)
│   │   │   ├── note-relationships/   # Note linking (types, repository, routes, test)
│   │   │   ├── note-tasks/           # Task CRUD (types, repository, routes, test)
│   │   │   ├── note-artifacts/       # Artifact CRUD (types, repository, routes, test)
│   │   │   ├── note-agent-actions/   # Agent action audit trail + batch review (types, repository, routes, test)
│   │   │   └── saved-views/          # Persisted saved views CRUD (types, repository, routes)
│   │   ├── mcp/
│   │   │   ├── note-tool-contracts.ts    # 8 MCP tool Zod schemas + definitions
│   │   │   ├── note-tools.ts             # 8 executable MCP tool implementations
│   │   │   ├── register-note-tools.ts    # Fastify plugin to register MCP tools
│   │   │   └── *.test.ts                 # MCP test files
│   │   └── server.ts                 # Fastify entrypoint (7 route modules + MCP)
│   ├── package.json
│   └── tsconfig.json
│
├── web/                              # Next.js 16 + React 19 web app (App Router)
│   ├── src/
│   │   ├── app/
│   │   │   ├── page.tsx              # Landing page
│   │   │   ├── layout.tsx            # Root layout
│   │   │   └── (app)/               # Authenticated route group
│   │   │       ├── dashboard/        # Dashboard with metrics + recent notes
│   │   │       ├── workspaces/       # Workspace list + filters
│   │   │       ├── search/           # Search with saved queries
│   │   │       ├── reviews/          # Approval queue + agent timeline
│   │   │       └── notes/[noteId]/   # Note detail with editor
│   │   ├── components/               # React UI components
│   │   │   ├── Sidebar.tsx
│   │   │   ├── AppShell.tsx
│   │   │   ├── MetadataPanel.tsx
│   │   │   ├── LinkedNotesPanel.tsx
│   │   │   ├── AgentTimeline.tsx
│   │   │   ├── CreateNoteModal.tsx      # Create note modal (workspace, title, body, tags)
│   │   │   └── LinkNoteModal.tsx        # Link note relationship modal
│   │   └── lib/                      # Pure TS clients + config
│   │       ├── product-config.ts     # Product identity + API URLs
│   │       ├── api-helpers.ts        # Shared getAccessToken() + createNotesApiClient()
│   │       ├── auth.ts               # @bytelyst/react-auth provider
│   │       ├── notes-client.ts       # Notes API client (backend)
│   │       ├── review-client.ts      # Approval queue, timeline, batch review
│   │       ├── saved-views-client.ts # Saved views CRUD client
│   │       ├── platform.ts           # @bytelyst/platform-client
│   │       ├── telemetry.ts          # @bytelyst/telemetry-client
│   │       ├── diagnostics.ts        # @bytelyst/diagnostics-client
│   │       ├── feature-flags.ts      # @bytelyst/feature-flag-client
│   │       ├── kill-switch.ts        # @bytelyst/kill-switch-client
│   │       ├── extraction-client.ts  # Extraction-service task extraction
│   │       ├── blob-client.ts        # @bytelyst/blob-client wrapper
│   │       ├── use-keyboard-shortcuts.ts # Global keyboard shortcuts hook
│   │       ├── use-debounce.ts       # Debounce hook for search
│   │       └── types.ts              # Shared TypeScript interfaces
│   ├── package.json
│   └── tsconfig.json
│
├── mobile/                           # React Native + Expo companion app
│   ├── src/
│   │   ├── app/                      # Expo Router screens
│   │   │   ├── (tabs)/              # 4-tab navigator (home, inbox, capture, settings)
│   │   │   ├── note/[noteId].tsx    # Note detail
│   │   │   └── auth.tsx             # Auth screen
│   │   ├── api/                     # API clients
│   │   │   ├── config.ts            # Product identity + API URLs
│   │   │   ├── auth.ts              # @bytelyst/auth-client
│   │   │   ├── notes.ts             # Notes API client
│   │   │   └── note-agent-actions.ts # Agent actions API client
│   │   ├── lib/                     # Platform SDK wrappers
│   │   │   └── platform.ts         # Telemetry, feature flags, kill switch, blob client
│   │   ├── store/                   # Zustand stores
│   │   │   ├── auth-store.ts
│   │   │   ├── inbox-store.ts
│   │   │   ├── workspace-store.ts
│   │   │   ├── notes-store.ts
│   │   │   └── mmkv-storage.ts      # MMKV persistent storage
│   │   └── theme/                   # Design tokens
│   ├── app.json                     # Expo config
│   └── package.json
│
├── shared/
│   └── product.json                 # Canonical product identity
│
├── docs/
│   ├── PRD.md                       # Product requirements
│   ├── ROADMAP.md                   # Master execution tracker
│   ├── ARCHITECTURE_REVIEW_AND_REUSE_ROADMAP.md
│   └── roadmaps/                    # Per-workstream roadmaps
│       ├── 00_MASTER_EXECUTION_PLAN.md
│       ├── 01_FOUNDATIONS_AND_DECISIONS.md
│       ├── 02_BACKEND_ROADMAP.md
│       ├── 03_WEB_ROADMAP.md
│       └── 04_MOBILE_ROADMAP.md
│
├── backend/Dockerfile               # Multi-stage Docker build for backend
├── web/Dockerfile                   # Multi-stage Docker build for web
├── docker-compose.yml               # Backend (4016) + web (3000)
├── scripts/docker-prep.sh           # Pack @bytelyst/* tarballs for Docker
├── .github/workflows/ci.yml         # GitHub Actions CI (backend + web + mobile)
├── AGENTS.md                        # This file
└── README.md
```

## 3. Tech Stack

| Layer | Technology |
|-------|-----------|
| **Backend** | Fastify 5, TypeScript ESM, Zod, jose (JWT), @bytelyst/datastore (Cosmos or memory) |
| **Web** | Next.js 16 (App Router), React 19, TailwindCSS v4, Zustand, Vitest |
| **Mobile** | React Native (Expo), TypeScript, expo-router, Zustand, MMKV |
| **Shared packages** | `@bytelyst/fastify-core`, `@bytelyst/config`, `@bytelyst/cosmos`, `@bytelyst/errors`, `@bytelyst/datastore`, `@bytelyst/api-client`, `@bytelyst/react-auth`, `@bytelyst/auth-client`, `@bytelyst/telemetry-client`, `@bytelyst/diagnostics-client`, `@bytelyst/feature-flag-client`, `@bytelyst/kill-switch-client`, `@bytelyst/platform-client`, `@bytelyst/blob-client` |
| **Platform** | platform-service (port 4003) for auth, flags, telemetry, billing, blob |
| **Extraction** | extraction-service (port 4005) for AI-powered task extraction |
| **Database** | Azure Cosmos DB via `@bytelyst/datastore` — `productId: "notelett"` |
| **Tests** | Vitest — 80 backend tests (19 files), 14 web tests (7 files), 23 mobile tests (4 files), 7 Playwright E2E (scaffolded) |

## 4. Coding Conventions

### MUST follow

- Every Cosmos document MUST include a `productId: "notelett"` field
- Backend modules follow `types.ts` → `repository.ts` → `routes.ts` pattern
- All repositories use `@bytelyst/datastore` getCollection() — never direct Cosmos SDK calls
- Web engine logic in `web/src/lib/` — pure TS, no React imports
- Web components in `web/src/components/` — React UI only
- Mobile API clients in `mobile/src/api/` — pure TS
- Theme tokens use `--nl-*` CSS custom properties (web) or `NoteLettTheme` (native)
- Commit messages: `type(scope): description` — types: `feat`, `fix`, `docs`, `refactor`, `test`, `chore`

### MUST NOT do

- Never use `console.log` in production code — use `req.log` or `app.log` in Fastify
- Never use `any` type — use Zod inference or explicit types
- Never hardcode colors — use theme tokens
- Never hardcode API URLs — use env vars or config
- Never hardcode product ID — use `PRODUCT_ID` from `product-config.ts`
- Never modify tests to make them pass — fix the actual code
- Never delete existing comments or documentation unless explicitly asked
- Never add emojis to code unless explicitly asked

## 5. Key Design Decisions

### MCP Tool Architecture
- 8 MCP tools: list, get, search, create_draft, update, link_notes, extract_tasks, attach_artifact
- Every write tool records an agent action audit trail
- All tools enforce product scope and user authentication
- Dry-run, idempotency key, and correlation ID support on all write tools

### Datastore Abstraction
- `@bytelyst/datastore` provides `CosmosDatastoreProvider` and `MemoryDatastoreProvider`
- `DB_PROVIDER` env var controls which provider is used (default: cosmos, test: memory)
- All 7 repositories use `getCollection()` — no direct Cosmos SDK calls

### Agent Action Audit Trail
- Every MCP tool write operation creates a `NoteAgentActionDoc` record
- Actions track: actorId, actorType, toolName, actionType, state, reason, before/after summaries
- Supports approval workflows: draft → proposed → approved/rejected → applied

### Cosmos Containers
- `notes` (partition: `/workspaceId`)
- `workspaces` (partition: `/userId`)
- `note_relationships` (partition: `/workspaceId`)
- `note_tasks` (partition: `/workspaceId`)
- `note_artifacts` (partition: `/workspaceId`)
- `note_agent_actions` (partition: `/workspaceId`)
- `saved_views` (partition: `/userId`)

## 6. Build & Test Commands

```bash
# ── Backend ────────────────────────────────────────
cd backend && npm run dev              # Dev server (port 4016)
cd backend && npm run typecheck        # tsc --noEmit
cd backend && npm test                 # 80 Vitest tests

# ── Web ────────────────────────────────────────────
cd web && npm run dev -- --webpack     # Dev server (port 3000)
cd web && npm run build -- --webpack   # Production build
cd web && npm run typecheck            # tsc --noEmit
cd web && npm test                     # 14 Vitest tests

# ── Mobile ─────────────────────────────────────────
cd mobile && npm start                 # Expo dev server
cd mobile && npm run typecheck         # tsc --noEmit
cd mobile && npm test                  # 23 Vitest tests
```

## 7. Backend API Endpoints

| Method | Path | Description |
|--------|------|-------------|
| GET/POST | `/api/notes` | List / create notes |
| GET/PATCH | `/api/notes/:id` | Note CRUD |
| POST | `/api/notes/:id/archive` | Archive note |
| POST | `/api/notes/:id/restore` | Restore note |
| POST | `/api/notes/:id/summarize` | Summarize note via extraction-service |
| GET | `/api/notes/export` | Export notes (JSON or Markdown) |
| GET | `/api/notes/search` | Search notes |
| GET/POST | `/api/workspaces` | List / create workspaces |
| GET/PATCH | `/api/workspaces/:id` | Workspace CRUD |
| GET/POST | `/api/note-relationships` | List / create relationships |
| GET/POST | `/api/note-tasks` | List / create tasks |
| GET/PATCH | `/api/note-tasks/:id` | Task CRUD |
| GET/POST | `/api/note-artifacts` | List / create artifacts |
| PATCH | `/api/note-artifacts/:id` | Update artifact |
| GET/POST | `/api/note-agent-actions` | List / create agent actions |
| PATCH | `/api/note-agent-actions/:id` | Update agent action state |
| POST | `/api/note-agent-actions/batch-review` | Batch approve/reject (up to 50) |
| GET/POST | `/api/saved-views` | List / create saved views |
| GET/PATCH/DELETE | `/api/saved-views/:id` | Saved view CRUD |
| GET | `/health` | Health check |

## 8. MCP Tools

| Tool Name | Description | Role |
|-----------|-------------|------|
| `notes.notes.list` | List notes in a workspace | viewer |
| `notes.notes.get` | Get a single note | viewer |
| `notes.notes.search` | Search notes with lexical query | viewer |
| `notes.notes.create_draft` | Create a note draft | admin |
| `notes.notes.update` | Update note title/body/status/tags | admin |
| `notes.relationships.link` | Create typed relationship between notes | admin |
| `notes.tasks.extract` | Extract tasks from note body | admin |
| `notes.artifacts.attach` | Attach artifact to a note | admin |


---

## Cross-Repo Automation

For periodic maintenance tasks that span all ByteLyst repos (test audits, coverage gaps, dependency checks, secret scans, typecheck sweeps), see the **Coding Agent Automation Playbook**:

> [`../learning_ai_common_plat/docs/devops/CODING_AGENT_AUTOMATION_PLAYBOOK.md`](../learning_ai_common_plat/docs/devops/CODING_AGENT_AUTOMATION_PLAYBOOK.md)

Key tasks: workspace hygiene sweep, cross-repo test suite, backend/web coverage gap analysis, TypeScript typecheck sweep, dependency health check, secret scan, code quality audit, AGENTS.md consistency check.