# Architecture

## Overview

Identity Platform follows an **Adobe-style holding model**: the Platform is the central hub/reference, and products (Bermooda, Hamsoo, future apps) are sub-products that connect to it. The Platform owns identity; products own their domain data.

```
┌──────────────────────────────────────────────────────────────┐
│                    IDENTITY PLATFORM                          │
│  ┌────────────┐  ┌────────────┐  ┌────────────┐              │
│  │  Identity  │  │ Authentication│ │ Organization │           │
│  │  (User)    │  │  (Session)   │  │  (Membership)│           │
│  └──────┬─────┘  └──────┬─────┘  └──────┬─────┘              │
│         └────────────────┴────────────────┘                  │
│            PRIVATE KEY (RS256) — NEVER LEAVES PLATFORM       │
└────────────────────────────┬─────────────────────────────────┘
                             │
              ┌──────────────┼──────────────┐
              ▼              ▼              ▼
        ┌───────────┐  ┌───────────┐  ┌───────────┐
        │  Bermooda │  │  Hamsoo   │  │  Future   │
        │   (ERP)   │  │ (Network) │  │   Apps    │
        └───────────┘  └───────────┘  └───────────┘
              ▲              ▲              ▲
              │  PUBLIC KEY (verify only)  │
              └──────────────┴──────────────┘
```

## Data Ownership Boundary

| Data | Owner | Notes |
|------|-------|-------|
| **User ID (UUID)** | Identity Platform | Immutable, globally unique |
| **Email & Phone** | Identity Platform | Verified, used for auth |
| **Password Hash** | Identity Platform | Never exposed |
| **Authentication & Sessions** | Identity Platform | Full lifecycle |
| **Organizations** | Identity Platform | Shared across products |
| **Memberships & Roles** | Identity Platform | Owner/Admin/Member |
| **Applications (OAuth Clients)** | Identity Platform | Per-product credentials |
| **Service Credentials** | Identity Platform | Client credentials flow |
| **Security Events / Audit Log** | Identity Platform | Immutable, queryable |
| **Employee & Payroll** | Bermooda | Domain data |
| **Profile & Resume** | Hamsoo | Domain data |
| **Projects & Listings** | Product | Domain data |

**Rule:** Identity Platform never stores domain data (payroll, resumes, projects). Products never store auth data (passwords, sessions, tokens).

## Modular Monolith (Backend)

The Django backend is a **modular monolith** with 11 apps:

| App | Responsibility |
|-----|----------------|
| `common` | Base models, permissions, pagination, rate limiting, exceptions |
| `identity` | Custom User model (UUID PK), managers, serializers |
| `authentication` | Login, refresh, logout, MFA-ready, rate limiting |
| `organization` | Organization CRUD, slug generation |
| `membership` | Membership model (User↔Org), roles, statuses |
| `application` | OAuth clients (confidential/public), scopes |
| `session` | Session tracking, device info, revocation |
| `security` | SecurityEvent model, audit log |
| `oauth` | OIDC discovery, JWKS, authorization server stubs |
| `config` | Settings, URLs, WSGI/ASGI |
| `admin` | Django admin registrations |

## API Versioning

All endpoints under `/api/v1/`. Breaking changes → `/api/v2/`.

OpenAPI schema via `drf-spectacular` at:
- JSON: `/api/schema/`
- Swagger UI: `/api/docs/`
- ReDoc: `/api/redoc/`

## Key Design Decisions

### UUID Primary Keys
- User PK = UUID (immutable, unguessable)
- All references use UUID — no integer IDs exposed

### RS256 Asymmetric Signing
- Platform holds **private key** (signing tokens)
- Products hold **public key** (verifying tokens via JWKS)
- Private key **never** leaves platform — products cannot forge tokens

### Session Model
- Each login creates a `Session` record (type: browser/api/device)
- Refresh token stored hashed; rotatable; revocable
- Device fingerprinting for detection

### Organization Model
- Single `Organization` model reusable as company/team/workspace
- `Membership` links User→Org with role (owner/admin/member) and status
- Products query memberships for authorization

### Rate Limiting
- Per-user and per-IP via Django cache (Redis in prod)
- Configurable windows; brute-force triggers lockout
- Endpoint-level decorators

### Security Events
- Immutable `SecurityEvent` model
- Types: `login_success`, `login_failed`, `logout`, `token_refreshed`, `session_revoked`, `password_changed`, `mfa_changed`, `suspicious_activity`
- Severity: `low`, `medium`, `high`, `critical`

## Web UI (server-rendered)

The account UI is rendered by Django templates — no Node.js toolchain, no
separate frontend service, no build step.

| Route | View | Purpose |
|-------|------|---------|
| `/` | `identity.ui_views.home` | Landing page |
| `/register/` | `identity.ui_views.register` | Self-registration (reuses `RegisterSerializer`) |
| `/account/` | `identity.ui_views.account` | Profile summary and active sessions |
| `/account/profile/` | `identity.ui_views.profile` | Edit self-service profile fields |
| `/account/security/` | `identity.ui_views.security` | Email verification, TOTP MFA, recovery codes, passkeys |
| `/account/organizations/` | `identity.ui_views.organizations` | Workspaces the user belongs to + create |
| `/account/organizations/<slug>/` | `identity.ui_views.organization_detail` | Members and roles (owners/admins only) |
| `/account/developers/` | `identity.ui_views.developers` | OAuth clients; staff can register apps and rotate secrets |
| `/account/password/` | `identity.ui_views.password_change` | Change password |
| `/account/reset-password/` | `identity.ui_views.password_reset` | Request and confirm reset (`?token=`) |
| `/p/<token>/` | `passport.ui_views.public_passport` | Public share-link passport page |
| `/sso/login/` | `sso.views.SsoLoginView` | Central login (session cookie for `*.hamsoo.me`) |
| `/oauth/consent` | `oauth.views.ConsentView` | First-time authorization consent |
| `/admin/` | Django admin | Users, organizations, applications, sessions, events |

Templates live next to their apps (`apps/*/templates/`) and share
`identity/templates/base.html`. Styling is self-contained inline CSS in that
base template, so WhiteNoise/collectstatic is not on the critical path for the
account pages.

### Why no SPA
The platform is an IdP: its pages are credential entry points. Server rendering
keeps passwords and tokens out of client-side state, gives CSRF protection by
default, and removes a second deployable. Products (Hamsoo, Bermooda) keep
their own frontends and talk to the API/OIDC endpoints.
## Deployment

### Docker Compose (Production-Ready)
```yaml
services:
  postgres:  postgres:16-alpine
  redis:     redis:7-alpine
  api:       gunicorn (3 workers, serves API + account pages)
```

### Environment Separation
- `.env` for secrets (not committed)
- `.env.example` as template
- `DJANGO_ENV=production` enforces `DJANGO_SECRET_KEY`

### Static Files
- Django: WhiteNoise (`CompressedManifestStaticFilesStorage`)
- Account pages carry their CSS inline; `collectstatic` is only needed for the
  Django admin assets.

## Scaling Considerations

| Component | Horizontal Scale |
|-----------|------------------|
| API (Django) | Stateless — add workers/containers behind LB |
| PostgreSQL | Read replicas for query-heavy workloads |
| Redis | Cluster mode for cache/sessions |
| Web UI (Django) | Horizontal scale with the API workers |

## Future: Multi-Region

- Platform deployable per region with shared user namespace
- Cross-region session sync via Redis
- DNS-based routing to nearest region