# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## What this is

A web app for manually fiscalizing (пробивать фискальні чеки) orders from an in-house CRM. Orders come from a CRM (own API, still unbuilt — see stub pattern below), delivery status and cash-on-delivery amount come from Nova Poshta, and fiscal receipts are created via the Checkbox API. Cashiers manually trigger receipt creation from a queue of "delivered, not yet fiscalized" orders; nothing fiscal happens automatically. Single cash register today, but the schema is built for several.

The full architecture rationale (why ARQ over Celery, why CRM is behind a `Protocol`, the receipt state machine, the money-units convention, etc.) lives in the project's plan file — read it before making structural changes. If it's not present in this checkout, ask the user for it rather than re-deriving the design from scratch.



Используй краткие ответы, без лишнего кода - только ключевая информация.

## Repository layout

```
backend/    FastAPI + SQLAlchemy (async) + Alembic + Postgres — see backend/app/
frontend/   React 19 + TypeScript + Vite — see frontend/src/
docker/     nginx.frontend.conf (SPA + /api reverse proxy to the api container)
docker-compose.yml   postgres, redis, migrate (one-shot), api, worker, frontend
```

Backend and frontend are independent projects with their own dependency files (`backend/pyproject.toml`, `frontend/package.json`) — always `cd` into the right one before running tooling.

## Commands

### Backend (from `backend/`)

Uses a local venv at `backend/.venv`, not a global interpreter.

```bash
.venv/Scripts/pip install -e ".[dev]"       # install deps (first time / after pyproject.toml changes)
.venv/Scripts/python -m pytest -q            # run all tests
.venv/Scripts/python -m pytest tests/test_security.py -q          # single file
.venv/Scripts/python -m pytest tests/test_security.py::TestAccessToken::test_rejects_expired_token -q  # single test
.venv/Scripts/python -m ruff check app tests # lint (must be clean — see rules below)
.venv/Scripts/alembic upgrade head           # apply migrations (needs POSTGRES_HOST=localhost etc. in .env)
.venv/Scripts/alembic revision -m "..."      # new migration — but see "Migrations" below, usually hand-written
.venv/Scripts/uvicorn app.main:app --reload  # run API standalone
python -m app.cli bootstrap                  # create first admin from FIRST_ADMIN_* in .env (idempotent)
python -m app.cli gen-keys                   # print a fresh SECRET_KEY + ENCRYPTION_KEY
```

Tests require `SECRET_KEY` and `ENCRYPTION_KEY` env vars to be set (any value works for tests; `tests/conftest.py` sets sane defaults via `os.environ.setdefault` before `app.core.config` is imported — order matters, config is read once at import time via `get_settings()`/`lru_cache`).

Tests that touch `Settings()` directly (e.g. `test_config.py`) need `secret_key` and `encryption_key` passed explicitly since `conftest.py`'s env-var defaults don't retroactively apply to already-`lru_cache`d instances.

No live Postgres is required for most tests — the migration-vs-models consistency test (`test_migration_matches_models.py`) statically diffs `alembic/versions/0001_*.py` against `Base.metadata` by regex, without a DB connection. Only actually running `alembic upgrade head` or the app against real data needs Postgres.

### Frontend (from `frontend/`)

```bash
npm install
npm run dev      # Vite dev server on :5173, proxies /api/* to http://localhost:8000 (see vite.config.ts)
npm run build     # tsc -b && vite build — treat tsc errors as build failures
npm run lint      # oxlint (not eslint — see .oxlintrc.json)
npm run preview
```

### Docker (from repo root)

```bash
cp .env.example .env    # then fill SECRET_KEY / ENCRYPTION_KEY via `python -m app.cli gen-keys`
docker compose up -d --build
docker compose run --rm api python -m app.cli bootstrap   # create first admin
docker compose logs -f api        # or: migrate, worker, frontend, postgres, redis
docker compose ps                 # migrate should show Exited(0) — it's a one-shot job, not a bug
```

`migrate` runs `alembic upgrade head` once and exits; `api`/`worker` `depends_on: migrate: condition: service_completed_successfully`. Don't add migration logic to the `api` container's startup — with multiple replicas that would race.

`worker` runs ARQ (`arq app.worker.WorkerSettings`): cron polls Nova Poshta statuses and Checkbox ETTN receipts every minute, plus the on-demand `create_ettn_receipt` job enqueued by the API. Its Dockerfile HEALTHCHECK is explicitly disabled in `docker-compose.yml` because the worker doesn't serve HTTP; don't re-enable it without giving it something to check.

## Backend architecture

- **Async everywhere.** SQLAlchemy 2.0 async ORM + `asyncpg`, one DSN (`app.core.config.Settings.database_url`) used by both the app and Alembic — no separate sync driver.
- **`app/core/`** — cross-cutting, no DB/HTTP knowledge: `config.py` (Pydantic Settings, `.env`-driven), `security.py` (argon2 passwords, JWT access tokens, refresh-token hashing), `crypto.py` (Fernet — for encrypting cash-register secrets in the DB, not yet wired to a model), `logging.py` (structlog, JSON in prod / console locally).
- **`app/db/models/`** — SQLAlchemy models. Every model file must be imported in `app/db/models/__init__.py` or Alembic autogenerate silently won't see its table.
- **`app/services/`** — business logic that touches the DB (`auth.py`, `audit.py`). Routers in `app/api/v1/` stay thin and call into these.
- **`app/api/deps.py`** — `CurrentUser`, `require_admin`/`require_cashier` deps for role gating. Roles: `admin`, `cashier`, `viewer` (`UserRole(enum.StrEnum)` — do NOT use `class X(str, enum.Enum)`, ruff's `UP042` rejects it).

### Auth model (already built, stage 2 of the plan)

- Access JWT (15 min) in memory only, on the frontend. Refresh token (7 days) is a random value; only its SHA-256 hash is stored in `refresh_tokens.token_hash` — never the raw value.
- Refresh rotates on every use (`services/auth.rotate_refresh_token`): the old row gets `revoked_at` + `replaced_by_id`, a new row is inserted. **Presenting an already-revoked refresh token is treated as theft** — it revokes every active token for that user and logs `AuditAction.TOKEN_REUSE_DETECTED`. Don't "simplify" this into a plain revoke-and-reissue without the reuse check.
- `get_current_user` re-reads the user from the DB on every request (not just from JWT claims) so deactivating a user takes effect immediately instead of waiting for the access token to expire.

### Audit log

`app/services/audit.py` — every state-changing endpoint should call `audit.record(...)` in the same DB transaction as the change it's logging, not after `commit()`. It auto-redacts a fixed set of key names (`password`, `*token`, `*secret`, `license_key`, `api_key`) — if you add a new secret-shaped field, add its key to `_REDACTED_KEYS` rather than trusting callers to remember.

### Config gotchas (both bit us for real, in production-shaped values — not hypothetical)

- **`CORS_ORIGINS`** is stored as a raw string (`cors_origins_raw`) and split in a `@property`, not as `list[str]` on the Settings field directly — pydantic-settings tries to JSON-parse complex-typed env vars before validators run, so a plain `a,b` string blows up at startup. Follow this pattern for any future comma-separated env var.
- **DSN building must percent-encode user/password** (`urllib.parse.quote(..., safe="")` in `Settings.database_url`) — `PostgresDsn.build` does not escape special characters itself, and a password containing `,`, `@`, `:`, or `/` silently corrupts the parsed port/host.
- **Alembic's `env.py` builds the async engine directly from `settings.database_url`** (`create_async_engine(...)`) instead of round-tripping through `config.set_main_option("sqlalchemy.url", ...)` / `alembic.ini`. `ConfigParser` treats `%` as an interpolation character, and a percent-encoded password (e.g. `%2C` for a comma) breaks `config.set_main_option` before migrations even start. Don't reintroduce the `alembic.ini`-based URL path.
- Docker `HEALTHCHECK`s must target `127.0.0.1`, not `localhost` — Alpine's `wget`/musl resolves `localhost` to `::1` first and does not fall back to IPv4 on connection refused (unlike `curl`, which tries all resolved addresses). A container can be fully working and still show `unhealthy` if this is wrong.

### Migrations

Hand-written, not autogenerated blindly — `alembic/versions/0001_users_and_audit.py` is deliberately explicit about column nullability, index names, and `ON DELETE` behavior, using `op.f(...)` with the naming convention defined in `app/db/base.py` (`NAMING_CONVENTION`) so constraint names are deterministic and droppable in `downgrade()`. Keep that pattern for new migrations. `tests/test_migration_matches_models.py` will fail if a migration and the models it's supposed to create drift — run it after writing a migration.

### Money and quantity units

Not yet enforced by types anywhere in the current code, but is a hard project convention for when order/receipt models land (plan stages 3+): **all money amounts are integer kopecks, all quantities are integer thousandths** (Checkbox API convention: `1 pcs = 1000`, `2.25 kg = 2250`). Never introduce `float`/`Decimal`-as-currency in new models — use `bigint`.

## Frontend architecture

- **Path alias `@/`** → `frontend/src/` (configured in both `tsconfig.app.json` `paths` and `vite.config.ts` `resolve.alias`). `tsconfig.app.json` needs `"ignoreDeprecations": "6.0"` alongside `baseUrl` — this TS version deprecates bare `baseUrl` otherwise.
- **`verbatimModuleSyntax: true`** — always use `import type { Foo }` for type-only imports, or the build fails.
- **`erasableSyntaxOnly: true`** — no TS `enum`. Use string-literal union types (see `api/types.ts` `UserRole`) or `StrEnum`-equivalents. This mirrors the backend's `UserRole` values by hand; there's no generated client yet, so keep `api/types.ts` in sync with `backend/app/schemas/*.py` manually.
- **No CORS anywhere, by design.** The frontend always calls relative `/api/v1/...` paths. In dev, Vite's `server.proxy` forwards `/api` to `http://localhost:8000`. In Docker/prod, `docker/nginx.frontend.conf` proxies `/api/` to `http://api:8000/api/` inside the compose network. If you ever need to call the API from a different origin, that's a sign something about this setup broke — don't just add CORS headers as a patch.
- **Token handling is split from React on purpose:** `api/tokenStore.ts` is a plain module-level singleton (not a React context) holding the in-memory access token and localStorage-backed refresh token, with a pub-sub `subscribeToTokens`. `api/client.ts` reads/writes it directly to do silent-refresh-and-retry on a 401 without importing React or `AuthContext` — importing `AuthContext` from `client.ts` would create an import cycle (`client → auth-context → client`). `features/auth/AuthContext.tsx` subscribes to the store for React state. Keep this separation when extending auth.
- **`oxlint`, not `eslint`.** Rule names and disable-comment syntax differ (`// oxlint-disable-next-line react/only-export-components`, not `eslint-disable-next-line react-refresh/only-export-components`). Config is `.oxlintrc.json`.
- Routing: `react-router-dom`. `features/auth/ProtectedRoute.tsx` gates authenticated-only routes via `<Outlet />`; `app/routes.tsx` is the single place routes are declared.
- Data fetching: `@tanstack/react-query`, provider set up in `app/App.tsx` with `refetchOnWindowFocus: false` (order/receipt data will be polled explicitly, not refetched on focus).

## Project status (see the plan for the full roadmap)

Stages 1–4 (scaffolding, auth/audit, CRM order queue, Nova Poshta tracking) are done. The dashboard has four tabs (`GET /orders?tab=no_receipt|has_receipt|received|refused`, `services/orders.OrderTab`); NP status beats receipt presence: an order whose NP status code is «received» (`NP_RECEIVED_STATUS_CODES`) shows only under «Полученные», a refusal (`NP_REFUSAL_STATUS_CODES`) only under «Отказы», whether or not it has a receipt. Checkbox ETTN receipts are implemented per `.plans/checkbox-ettn-receipts.md` but not yet verified on a real cash register.

### Checkbox ETTN receipts

- We never fiscalize ourselves: the cashier creates an **ETTN receipt** in Checkbox bound to a Nova Poshta TTN with payment control; Checkbox fiscalizes it when the customer pays at the NP branch. Invariant: `order total − prepayment == np_cod_amount_kopecks`. Prepayment goes into the receipt as a plain `DISCOUNT` («Знижка»), **not** `PRE_PAYMENT` — the live API rejects `PRE_PAYMENT` on ETTN with 400 `third_party.generic`. The live API also returns statuses lowercase (`EttnOut` upper-cases them).
- Two-phase create: `POST /receipts` writes `Receipt(pending)` + audit and commits, then enqueues `create_ettn_receipt`; the worker calls Checkbox. A timeout leaves the row `pending` with `error` set — the retry first looks the TTN up via `find_ettn` instead of blindly re-posting (would create a second receipt). Keep this.
- State machine and the "one live receipt per order" partial unique index live in `app/db/models/receipt.py`. `orders.receipt_created_at` is set on request and reset to NULL when a receipt ends `failed`/`cancelled` (order goes back to the queue).
- Once Checkbox accepts the receipt, the order is moved to `PACKED` in the CRM (`services/receipts.sync_crm_statuses`, marked by `receipts.crm_status_set_at`; runs right after creation and is retried by cron). The live exoCRM `SetStatus` differs from its docs: params must be `{"Orders": [id], "Status": ...}` (the documented `{"ID": ...}` returns "Undefined order list."), and the reply has no `status: OK` — success is `{"<id>": {"Status": "Success"}}`.
- Nova Poshta's rate limit comes back through Checkbox as a 4xx with `code=third_party.generic` and «To many requests» / `20000401501`, not as a 429. `http_client._transient_error` maps it to `CheckboxRateLimitedError`: the receipt stays `pending` and the worker retries with `arq.Retry`. The client also sends requests one at a time with a `CHECKBOX_MIN_REQUEST_INTERVAL_MS` pause, so don't parallelize Checkbox calls in the worker.
- Each cash register has its own Nova Poshta API key (`cash_registers.np_api_key_enc`, Fernet). `sync_np_statuses` polls TTNs with register keys and binds the order to the register whose key sees the TTN as its own (`orders.cash_register_id`; ownership = response contains `PhoneSender` — a foreign key gets a truncated reply without sender/`AfterpaymentOnGoodsCost`). Receipts are created from the order's register, not the default one; an unbound order is rejected. `NOVA_POSHTA_API_KEY` env is only read by migration 0008.
- ETTN does **not** work on a Checkbox test cash register. Locally use `CHECKBOX_USE_STUB=true`; client selection is only in `services/checkbox/client.get_checkbox_client()`.