marketplaces/docs/backend/BACKEND-HANDOFF.md

# Backend handoff — start here

Single entry point for a backend developer picking this up cold. Written 2026-08-18.

## 1. What this is

`marketplaces` is a multi-tenant marketplace platform frontend (Angular 22). The frontend is built and waiting; **there is no backend yet**. Every wire contract the backend needs to implement is already written and sitting in this directory — see [README.md](README.md) for the full index and build order.

## 1a. Multi-tenancy — the thing that shapes every endpoint

The final executable infrastructure/backend contract is
[TENANT-API-DOMAIN-HANDOFF.md](TENANT-API-DOMAIN-HANDOFF.md). Follow it for
hostname normalization, CORS, nginx, TLS, CI secrets, and acceptance checks.

One deployed bundle serves **every customer domain**. There is no per-tenant build. The chain is:

1. [`TenantResolverService`](../../src/app/core/config/tenant-resolver.service.ts) reads the complete current browser hostname and protocol (localhost still uses the development proxy).
2. [`ApiConfigService`](../../src/app/core/config/api-config.service.ts) uses one API host per base domain: both `example.com` and `store1.example.com` use `api.example.com`.
3. `ApiBootstrapProvider`, auth, legacy API calls, and versioned `/api/...` calls all use that same base.
4. Each base domain owns one API DNS/TLS/reverse-proxy entry. nginx validates the browser origin and forwards the complete storefront hostname as `X-Storefront-Host`.
5. Backend tenant lookup uses that trusted storefront hostname, not the shared API `Host`; frontend nginx remains `default_server` / `server_name _`, so any attached storefront domain receives the same bundle.

**What this means for you:** the bootstrap endpoint is the single most important thing to build after auth. Every request must be tenant-scoped server-side, and a tenant must never be able to read another tenant's data — return `403`, not an empty result (see [TRACK-S §2](TRACK-S-SECURITY-RBAC-CONTRACT.md)). The frontend supplies the tenant identity from the hostname; the backend must treat that as an untrusted hint and derive real scope from the authenticated session.

Constraints already fixed by the frontend design (see the platform-vision facts in `docs/context/`): no marketplace-specific code or hardcoded marketplace data in the frontend; bootstrap carries only what is needed before app start (branding, languages, homepage layout, navigation, enabled widgets, footer pages) and **never** products, orders, cart, or users.

[PHASE-9](PHASE-9-TENANT-REGISTRY-DOMAINS-CONTRACT.md) covers the marketplace registry, domain attachment, and publish/revision model.

## 2. Read in this order

1. [README.md](README.md) — index of all contracts, build order, and what's deliberately excluded.
2. [PHASE-1-MONEY-FX-PAYMENTS-CONTRACT.md](PHASE-1-MONEY-FX-PAYMENTS-CONTRACT.md) — start here. Everything after depends on the money model.
3. Phases 2→4 — the rest of the launch gate (orders, catalog, connectors).
4. [TRACK-S-SECURITY-RBAC-CONTRACT.md](TRACK-S-SECURITY-RBAC-CONTRACT.md) — **gates the launch.** Today the admin role model is decorative: nothing server-side enforces any permission. §8 covers per-marketplace bootstrap admin accounts and self-service sub-admin management.
5. [TRACK-A-ANALYTICS-CONTRACT.md](TRACK-A-ANALYTICS-CONTRACT.md) — longest lead time, start it in parallel with Phase 1.
6. Phases 5→10 — post-launch-gate.
7. [PARTNER-PROVISIONING-API-CONTRACT.md](PARTNER-PROVISIONING-API-CONTRACT.md) — the inbound partner API. Read it **before implementing Phase 1**, not after: it adds `RoutingContext` to `CheckoutSession`/`PaymentIntent`/`Payment` ([Phase 1 §6.5](PHASE-1-MONEY-FX-PAYMENTS-CONTRACT.md)) and two levels above `Marketplace` ([Phase 9 §1](PHASE-9-TENANT-REGISTRY-DOMAINS-CONTRACT.md)). Building the partner API itself can wait; carrying its routing dimension in the payments tables cannot.

[../../BACKEND-API-REFERENCE.md](../../BACKEND-API-REFERENCE.md) documents the *current* live API surface (legacy endpoints, error envelope, mock-only areas). New endpoints use `/api/v2/...` namespaces; legacy endpoints are not being migrated.

## 3. Auth — read before writing any endpoint

Auth is no longer part of this repo. It lives in `@marketplaces/auth`, published from [vitanovaPackages](https://sources.vitanova.network/sdarbinyan/vitanovaPackages.git). See [../PACKAGES-USAGE.md](../PACKAGES-USAGE.md) for the full client surface. What matters on the backend side:

**Two mechanisms exist client-side.**

- **Telegram QR/session (live).** Endpoints under `{authApiUrl}/users/sessions` — `POST` to create, `GET /{id}` to poll, `DELETE /{id}` to log out. Both customer and admin login call the *same* endpoints; only client-side storage differs. The response shape is normalized permissively client-side (many key spellings accepted), but a clean implementation should return `{ webSessionID, user: { userId, username, firstName, lastName }, status, expiresAt }`.
- **Ed25519 challenge/response (not built).** `GET /api/admin/auth/challenge`, `POST /api/admin/auth/verify`, `POST /api/admin/auth/refresh`, `POST /api/admin/auth/logout`. Contracts in [TRACK-S](TRACK-S-SECURITY-RBAC-CONTRACT.md) and the package's `ed25519/models/auth-api.model.ts`. Until these ship, the client shows a `backend-unavailable` screen — nothing is mocked.

**The critical gap:** the session API has no concept of "admin." The frontend cannot distinguish an admin session from a customer one — it only chooses where to *store* the result. **Every admin endpoint must independently verify authorization server-side.** Client-side guards are UI convenience, never security. This is the single most serious open issue in the system.

Admin requests carry `AdminWebSessionID: <sessionId>` (and `Authorization: Bearer <token>` once admin JWTs exist) on paths containing `/admin/`, `/backoffice/`, `/builder/`, `/media/`.

## 4. Environment / infrastructure state

Dev server `213.21.246.138` (user `seto`, sudo, SSH key provided separately).

| Thing | State |
|---|---|
| nginx 1.24 | **Installed, running.** Config at `/etc/nginx/sites-enabled/marketplaces-dev.conf`. Serves frontend from `/srv/marketplaces/current/frontend`, backoffice from `/srv/marketplaces/current/backoffice`, proxies `/api/` → `127.0.0.1:8080`. `/health` returns `ok`. |
| Go toolchain | Installed (`/usr/local/bin/go`). |
| Backend service on :8080 | **Not running.** Nothing is listening. `/srv/marketplaces/current/api` is an empty shell. nginx's `/api/` proxy currently 502s. |
| PostgreSQL | **Installed but inactive.** Needs starting, a database, a user, and schema before anything works. |
| Shared packages | `@marketplaces/auth` installs over plain git from a release branch — no registry, token, or tunnel needed. `npm install` works out of the box. |
| Verdaccio (npm registry) | Running in Docker on port 4873, but **superseded and unused** — nothing depends on it. See [../PACKAGE-EXTRACTION.md](../PACKAGE-EXTRACTION.md) §5. |
| Firewall (ufw) | Active. 80/tcp, 443/tcp, OpenSSH. |
| TLS / certbot | **Not installed.** No certificates. Everything is plain HTTP today. For multi-tenant this is real work: every customer domain needs a certificate (per-domain issuance, or a wildcard if all tenants sit under one apex). |
| DNS / dynamic subdomains | **Not set up.** No domain currently points at the server (reverse DNS is the provider default `silky-bronze.ptr.network`). No wildcard record, no per-tenant subdomain automation, no Hostinger DNS integration. The *application* is fully multi-tenant (§1a) — this is the missing infrastructure underneath it. [PHASE-9](PHASE-9-TENANT-REGISTRY-DOMAINS-CONTRACT.md) specifies the target. |
| Frontend deploy (CD) | **None.** Pushing to `main` deploys nothing. `architecture-governance.yml` builds and checks boundaries but has no deploy step, and nothing writes to `/srv/marketplaces/current/frontend`. Deploys are manual today. |
| CI runner | None on this server; `sources.vitanova.network` CI runs elsewhere. |

## 5. To get a working dev environment

Nothing here is done yet — this is the setup a backend dev does on day one.

1. Start and configure PostgreSQL; create the database and application user.
2. Design the schema from the Phase 1–4 contracts (schema design is explicitly the backend's own call — the contracts specify entities, endpoints, and invariants, never tables). Tenant scoping belongs in the schema from day one; retrofitting it is painful.
3. Build the API service, listen on `127.0.0.1:8080`. nginx already proxies `/api/` to it.
4. Implement the **bootstrap config endpoint** (§1a) — without it the frontend cannot render for any tenant.
5. Implement the Telegram session endpoints — the login flow is fully built client-side and blocked only on these.
6. Implement `GET /api/identity/v1/session/permissions` ([TRACK-S §2](TRACK-S-SECURITY-RBAC-CONTRACT.md)) — frontend route guards derive from it.
7. Seed per-marketplace bootstrap admins ([TRACK-S §8](TRACK-S-SECURITY-RBAC-CONTRACT.md)): login = marketplace slug, cryptographically random one-time password delivered out of band, `mustChangePassword: true`.

Steps 4–6 unblock the entire frontend. Everything after is feature work.

## 6. Frontend deploy

```bash
git clone <marketplaces repo>
npm install     # pulls @marketplaces/auth over git, no credentials needed
npm run build   # -> dist/dexarmarket
```

Angular 22, Node 24+. nginx serves `/srv/marketplaces/current/frontend`.
[`deploy.yml`](../../.github/workflows/deploy.yml) builds and atomically deploys
pushes to `main`; one deployment updates every domain at once. Before activation,
the workflow reconciles TLS, exact CORS, and reverse proxying for every host in
`STOREFRONT_DOMAINS`. Production deployment requires the documented CI secrets
and the one-time [`server-setup.sh`](../../scripts/deploy/server-setup.sh) run.

## 7. Known open decisions

- Registry reachability for CI (reverse proxy + TLS, or a different registry entirely).
- ~~Backend ownership.~~ Answered 2026-08-18: implemented by a separate backend developer against this contract set.
- Additional payment providers (wallets, BNPL) — [Phase 7 §4](PHASE-7-PAYMENTS-RECONCILIATION-CONTRACT.md).
- Per-connector marketplace adapters — written per partner at onboarding, [Phase 4 §8](PHASE-4-CONNECTOR-FRAMEWORK-CONTRACT.md).
- Backfill of `Company`/`Project`/`PaymentPoint` for existing marketplaces — sequence specified in [Phase 9 §1.2](PHASE-9-TENANT-REGISTRY-DOMAINS-CONTRACT.md), not yet scheduled.