leocrm/architecture.md

# LeoCRM — Architecture Document

> **Scope:** This document covers both v1 (Core) and v2 (Plugin) architecture.
> **v1 Features:** 73 Core features (F-AUTH, F-COMP, F-CONT, F-CORE, F-DATA, F-UI, F-A11Y, F-SEC, F-INFRA, F-INT, F-MIG, F-NAV, F-SET, F-PLUGIN, F-SCHED, F-SEARCH, F-TEST, F-ENV, F-DOC, F-PERF, F-AI, F-WF)
> **v2 Features:** 70 Plugin features (F-CAL, F-DMS, F-FILE, F-FILEUI, F-LINK, F-MAIL, F-PERM, F-TAG)
> **v1 Tasks:** T01, T02, T03, T07, T09, T10
> **v2 Tasks:** T04, T05, T06, T11, T08a, T08b, T08c

**Projekt:** leocrm — Greenfield
**Architekt:** Solution Architect (Agent Zero)
**Datum:** 2026-06-28
**Status:** Draft — ready for review

---

## 1. System Architecture

### Overview

LeoCRM ist ein Multi-Tenant CRM mit Plugin-basiertem Erweiterungs-System. Die Architektur folgt API-First-Prinzip: alle Features sind primär über REST API nutzbar, die React SPA ist ein API-Client.

### High-Level Diagramm

```
┌───────────────────────────────────────────────────────┐
│                    Coolify (Docker)                     │
├───────────────────────────────────────────────────────┤
│  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐ │
│  │  React SPA    │  │  FastAPI     │  │  ARQ Worker  │ │
│  │  (Vite build) │  │  Backend     │  │  (async jobs)│ │
│  │  :80          │  │  :8000       │  │  (background)│ │
│  └──────┬───────┘  └──────┬───────┘  └──────┬───────┘ │
│         │                  │                  │         │
│         │   ┌──────────────┼──────────────┐   │         │
│         │   │  PostgreSQL 16  │  Redis   │   │         │
│         │   │  (data + FTS)    │ (cache+  │   │         │
│         │   │  :5432           │  queue)  │   │         │
│         │   └─────────────────┴──────────┘   │         │
│         │                                    │         │
│  ┌──────┴─────────────────────────────────────┴──────┐ │
│  │  OnlyOffice Document Server :8080 (optional)      │ │
│  └───────────────────────────────────────────────────┘ │
│  ┌───────────────────────────────────────────────────┐ │
│  │  Storage Volume (/data/leocrm)                    │ │
│  │  S3-kompatibel oder lokales Volume               │ │
│  └───────────────────────────────────────────────────┘ │
└───────────────────────────────────────────────────────┘
```

### Services (Docker Compose)

| Service | Container | Port | Purpose |
|---------|----------|------|--------|
| `backend` | FastAPI + Uvicorn | 8000 | REST API, Session-Auth, OpenAPI |
| `frontend` | Nginx + React SPA (static) | 80 | React SPA, served as static files |
| `postgres` | PostgreSQL 16 | 5432 | Primary database, Full-Text-Search |
| `redis` | Redis 7 | 6379 | Cache, Session-Store, Job-Queue |
| `worker` | ARQ Worker (Python) | — | Background jobs (export, mail-sync, reminders) |
| `onlyoffice` | OnlyOffice Document Server | 8080 | Inline Office-Editing (optional) |

### Backend Architecture

```
backend/
├── app/
│   ├── main.py                 — FastAPI app, lifespan, middleware
│   ├── config.py               — Pydantic Settings (env vars)
│   ├── deps.py                 — Dependency injection (auth, db, tenant)
│   ├── core/                   — Core infrastructure
│   │   ├── db/                 — SQLAlchemy engine, session, base model
│   │   ├── tenant.py           — Tenant-scoping middleware/query filter
│   │   ├── auth.py             — Session auth, password hashing, RBAC
│   │   ├── event_bus.py        — Event publishing/subscribing
│   │   ├── service_container.py — DI container for services
│   │   ├── storage.py          — File storage backend (S3/local)
│   │   ├── cache.py            — Redis cache wrapper
│   │   ├── jobs.py             — ARQ job queue integration
│   │   ├── notifications.py    — Notification service
│   │   └── audit.py            — Audit log middleware
│   ├── models/                 — SQLAlchemy models (one file per module)
│   ├── schemas/                — Pydantic schemas (one file per module)
│   ├── services/               — Business logic (one file per module)
│   ├── routes/                  — FastAPI routers (one file per module)
│   ├── plugins/                — Plugin system
│   │   ├── registry.py         — Plugin discovery, registration
│   │   ├── manifest.py         — Plugin manifest schema
│   │   ├── lifecycle.py        — Install/activate/deactivate/uninstall
│   │   ├── migrations.py       — Plugin DB migration runner
│   │   ├── ui_registry.py      — Plugin UI component registration
│   │   └── builtins/           — Built-in plugins
│   │       ├── dms/            — DMS plugin
│   │       ├── calendar/       — Calendar plugin
│   │       ├── mail/           — Mail plugin
│   │       └── tags/           — Tags plugin
│   ├── workflows/              — Workflow engine
│   │   ├── engine.py           — Workflow execution engine
│   │   ├── code/               — Code-based core workflows
│   │   └── models.py           — Workflow SQLAlchemy models
│   ├── ai/                     — KI-Copilot integration
│   │   ├── copilot.py          — Copilot query/execute logic
│   │   ├── llm_client.py       — LLM API client (OpenAI/Anthropic)
│   │   └── models.py           — ai_conversations model
│   └── utils/                  — Shared utilities (validation, export, import)
├── tests/                     — pytest + httpx
├── alembic/                    — DB migrations
├── pyproject.toml
└── Dockerfile
```

### Frontend Architecture

```
frontend/
├── src/
│   ├── main.tsx               — React entry point
│   ├── App.tsx                — Root component, router, providers
│   ├── api/                   — API client (axios/fetch), interceptors
│   ├── components/            — Shared UI components
│   │   ├── layout/            — Shell, Sidebar, TopBar, ContentArea
│   │   ├── ui/               — Button, Input, Select, Modal, Toast, Table
│   │   └── shared/           — EmptyState, LoadingState, ConfirmDialog, Pagination
│   ├── features/              — Feature modules
│   │   ├── auth/             — Login, PasswordReset, UserManagement
│   │   ├── companies/        — CompanyList, CompanyDetail, CompanyForm
│   │   ├── contacts/         — ContactList, ContactDetail, ContactForm
│   │   ├── settings/         — SettingsTree, ProfileSettings, RoleEditor
│   │   ├── audit/            — AuditLog
│   │   ├── dashboard/        — Dashboard
│   │   └── search/           — GlobalSearch
│   ├── plugins/              — Plugin UI loading framework
│   │   ├── PluginRegistry.tsx — Plugin UI component registry
│   │   └── PluginLoader.tsx   — Dynamic plugin component loading
│   ├── hooks/                 — Custom React hooks
│   ├── store/                 — Zustand stores
│   ├── i18n/                  — react-i18next setup + locale files
│   ├── styles/                — Global CSS, design tokens, accessibility
│   └── utils/                  — Utilities (format, validation, export)
├── public/
├── index.html
├── vite.config.ts
├── package.json
├── tsconfig.json
└── Dockerfile
```

---

## 2. DB Schema

### Design Principles (F-DATA-03, F-DATA-04, F-DATA-06)

> **v1 Core Features:**
> - F-DATA-03: Daten-Validierung — Pydantic schemas validate all API inputs
> - F-DATA-04: PostgreSQL als Datenbank — PostgreSQL 16 with Row-Level Security for tenant isolation
> - F-DATA-06: ARIA-Rollen auf DataTable — frontend tables use ARIA roles for accessibility

- **Multi-Tenant:** Jede Tabelle hat `tenant_id` (UUID). ORM filtert automatisch.
- **Soft-Delete:** `deleted_at TIMESTAMP NULL` auf Companies, Contacts, Folders, Files.
- **Audit Trail:** `created_at`, `updated_at`, `created_by`, `updated_by` auf alle Core-Tabellen.
- **UUID Primary Keys:** Alle IDs sind UUID (gen_random_uuid() default).
- **Timestamps:** `TIMESTAMPTZ` für alle Datumsfelder.

### Core Tables

#### `tenants`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK, default gen_random_uuid() |
| name | VARCHAR(200) | NOT NULL |
| slug | VARCHAR(100) | UNIQUE, NOT NULL |
| created_at | TIMESTAMPTZ | NOT NULL, default NOW() |
| updated_at | TIMESTAMPTZ | NOT NULL, default NOW() |

#### `users`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id, NOT NULL |
| email | VARCHAR(255) | NOT NULL |
| name | VARCHAR(200) | NOT NULL |
| password_hash | VARCHAR(255) | NOT NULL (bcrypt cost=12) |
| role | VARCHAR(50) | NOT NULL, default 'viewer' |
| is_active | BOOLEAN | default true |
| preferences | JSONB | default '{}' |
| default_calendar_id | UUID | NULL (v2: FK→calendars.id, added in v2 migration) |
| default_mail_account_id | UUID | NULL (v2: FK→mail_accounts.id, added in v2 migration) |
| created_at | TIMESTAMPTZ | NOT NULL |
| updated_at | TIMESTAMPTZ | NOT NULL |

**Unique:** (tenant_id, email)

#### `user_tenants` (N:M — User kann mehreren Tenant angehören)
| Column | Type | Constraints |
|--------|------|-------------|
| user_id | UUID | FK→users.id |
| tenant_id | UUID | FK→tenants.id |
| is_default | BOOLEAN | default false |

**PK:** (user_id, tenant_id)

#### `roles`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(100) | NOT NULL |
| permissions | JSONB | NOT NULL (module→action→read/write/delete/admin) |
| field_permissions | JSONB | default '{}' (field→read/write/hidden) |
| created_at | TIMESTAMPTZ | NOT NULL |

#### `sessions` (Audit Trail — primary session store is Redis)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| user_id | UUID | FK→users.id |
| tenant_id | UUID | FK→tenants.id (active tenant) |
| csrf_token | VARCHAR(255) | NOT NULL |
| expires_at | TIMESTAMPTZ | NOT NULL |
| created_at | TIMESTAMPTZ | NOT NULL |

**Note:** Session lookup at runtime uses Redis (`session:{id}` with TTL=8h). This PostgreSQL table is an immutable audit trail of all sessions ever created, used for security analysis and forensic logging. Session invalidation deletes the Redis key; the PostgreSQL record persists.

#### `companies`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id, NOT NULL |
| name | VARCHAR(100) | NOT NULL |
| account_number | VARCHAR(40) | NULL |
| industry | VARCHAR(50) | NULL (picklist) |
| account_type | VARCHAR(50) | NULL (picklist) |
| ownership | VARCHAR(50) | NULL (picklist) |
| employees | INTEGER | NULL |
| annual_revenue | DECIMAL(15,2) | NULL |
| phone | VARCHAR(30) | NULL |
| fax | VARCHAR(30) | NULL |
| email | VARCHAR(255) | NULL |
| website | VARCHAR(500) | NULL |
| rating | VARCHAR(20) | NULL (Hot/Warm/Cold) |
| parent_account_id | UUID | FK→companies.id NULL (self-ref) |
| billing_street | VARCHAR(250) | NULL |
| billing_city | VARCHAR(100) | NULL |
| billing_state | VARCHAR(100) | NULL |
| billing_postal_code | VARCHAR(20) | NULL |
| billing_country | VARCHAR(100) | NULL |
| shipping_street | VARCHAR(250) | NULL |
| shipping_city | VARCHAR(100) | NULL |
| shipping_state | VARCHAR(100) | NULL |
| shipping_postal_code | VARCHAR(20) | NULL |
| shipping_country | VARCHAR(100) | NULL |
| description | TEXT | NULL |
| sic_code | VARCHAR(10) | NULL |
| ticker_symbol | VARCHAR(30) | NULL |
| account_site | VARCHAR(80) | NULL |
| deleted_at | TIMESTAMPTZ | NULL (soft-delete) |
| created_at | TIMESTAMPTZ | NOT NULL |
| updated_at | TIMESTAMPTZ | NOT NULL |
| created_by | UUID | FK→users.id |
| updated_by | UUID | FK→users.id |

**Index:** (tenant_id), (tenant_id, deleted_at), (tenant_id, name), (tenant_id, industry), (tenant_id, billing_country), (tenant_id, rating)

#### `contacts`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id, NOT NULL |
| first_name | VARCHAR(50) | NULL |
| last_name | VARCHAR(50) | NOT NULL |
| salutation | VARCHAR(20) | NULL |
| email | VARCHAR(255) | NULL |
| secondary_email | VARCHAR(255) | NULL |
| phone | VARCHAR(30) | NULL |
| mobile | VARCHAR(30) | NULL |
| home_phone | VARCHAR(30) | NULL |
| fax | VARCHAR(30) | NULL |
| title | VARCHAR(100) | NULL |
| department | VARCHAR(100) | NULL |
| reports_to | UUID | FK→contacts.id NULL |
| date_of_birth | DATE | NULL |
| assistant | VARCHAR(50) | NULL |
| assistant_phone | VARCHAR(30) | NULL |
| mailing_street | VARCHAR(250) | NULL |
| mailing_city | VARCHAR(100) | NULL |
| mailing_state | VARCHAR(100) | NULL |
| mailing_postal_code | VARCHAR(20) | NULL |
| mailing_country | VARCHAR(100) | NULL |
| other_street | VARCHAR(250) | NULL |
| other_city | VARCHAR(100) | NULL |
| other_state | VARCHAR(100) | NULL |
| other_postal_code | VARCHAR(20) | NULL |
| other_country | VARCHAR(100) | NULL |
| skype_id | VARCHAR(50) | NULL |
| linkedin | VARCHAR(500) | NULL |
| twitter | VARCHAR(50) | NULL |
| description | TEXT | NULL |
| deleted_at | TIMESTAMPTZ | NULL (soft-delete) |
| created_at | TIMESTAMPTZ | NOT NULL |
| updated_at | TIMESTAMPTZ | NOT NULL |
| created_by | UUID | FK→users.id |
| updated_by | UUID | FK→users.id |

**Index:** (tenant_id, deleted_at), (tenant_id, last_name), (tenant_id, first_name), (tenant_id, email), GIN(tenant_id, to_tsvector('simple', last_name||' '||first_name||' '||email))

#### `company_contacts`
| Column | Type | Constraints |
|--------|------|-------------|
| company_id | UUID | FK→companies.id |
| contact_id | UUID | FK→contacts.id |
| tenant_id | UUID | FK→tenants.id (denormalized for filter) |
| created_at | TIMESTAMPTZ | NOT NULL |

**PK:** (company_id, contact_id)
**Index:** (tenant_id), (contact_id)

#### `audit_log`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| action | VARCHAR(50) | NOT NULL (create/update/delete/gdpr_delete/login) |
| entity_type | VARCHAR(50) | NOT NULL |
| entity_id | UUID | NULL |
| changes | JSONB | NULL (field→old/new) |
| timestamp | TIMESTAMPTZ | NOT NULL |

**Index:** (tenant_id, timestamp), (tenant_id, entity_type), (tenant_id, user_id)

#### `deletion_log` (unveränderlich)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| entity_type | VARCHAR(50) | NOT NULL |
| entity_id | UUID | NOT NULL |
| entity_snapshot | JSONB | NOT NULL (full record before deletion) |
| deleted_at | TIMESTAMPTZ | NOT NULL |

#### `notifications`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| type | VARCHAR(20) | NOT NULL (info/warning/error/success) |
| title | VARCHAR(200) | NOT NULL |
| body | TEXT | NULL |
| read_at | TIMESTAMPTZ | NULL |
| created_at | TIMESTAMPTZ | NOT NULL |

**Index:** (tenant_id, user_id, read_at)

#### `password_reset_tokens`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| token_hash | VARCHAR(255) | NOT NULL |
| expires_at | TIMESTAMPTZ | NOT NULL |
| used_at | TIMESTAMPTZ | NULL |

#### `plugins` (Plugin Registry in DB)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(100) | NOT NULL |
| version | VARCHAR(20) | NOT NULL |
| status | VARCHAR(20) | NOT NULL (installed/active/inactive/error) |
| manifest | JSONB | NOT NULL |
| installed_at | TIMESTAMPTZ | NOT NULL |
| activated_at | TIMESTAMPTZ | NULL |

#### `api_tokens` (API Token Auth — post-MVP, architecture ready)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| token_hash | VARCHAR(255) | NOT NULL (SHA-256 hash of token) |
| name | VARCHAR(200) | NOT NULL (user-provided label) |
| scopes | JSONB | NOT NULL (array of scope strings, e.g. ["companies:read","contacts:write"]) |
| expires_at | TIMESTAMPTZ | NULL (NULL = no expiry) |
| last_used_at | TIMESTAMPTZ | NULL |
| created_at | TIMESTAMPTZ | NOT NULL |
| revoked_at | TIMESTAMPTZ | NULL |

**Index:** (tenant_id, user_id), (token_hash)

### Workflow Engine Tables

#### `workflows` (Workflow Definition)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(200) | NOT NULL |
| description | TEXT | NULL |
| entity_type | VARCHAR(50) | NOT NULL (company/contact/entry/mail/generic) |
| trigger_type | VARCHAR(30) | NOT NULL (manual/event/schedule) |
| trigger_config | JSONB | NULL (event name or cron expression) |
| steps | JSONB | NOT NULL (ordered array of step definitions) |
| is_active | BOOLEAN | default true |
| created_by | UUID | FK→users.id |
| created_at | TIMESTAMPTZ | NOT NULL |
| updated_at | TIMESTAMPTZ | NOT NULL |

**Index:** (tenant_id, entity_type), (tenant_id, is_active)

#### `workflow_instances` (Running Workflow)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| workflow_id | UUID | FK→workflows.id |
| entity_type | VARCHAR(50) | NOT NULL |
| entity_id | UUID | NULL |
| current_step_index | INTEGER | NOT NULL default 0 |
| status | VARCHAR(20) | NOT NULL (pending/in_progress/approved/rejected/cancelled/completed) |
| context | JSONB | NOT NULL (trigger data + step results) |
| initiated_by | UUID | FK→users.id |
| created_at | TIMESTAMPTZ | NOT NULL |
| updated_at | TIMESTAMPTZ | NOT NULL |
| completed_at | TIMESTAMPTZ | NULL |

**Index:** (tenant_id, status), (tenant_id, workflow_id), (tenant_id, initiated_by)

#### `workflow_step_history` (Audit Trail per Step)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| instance_id | UUID | FK→workflow_instances.id |
| step_index | INTEGER | NOT NULL |
| step_name | VARCHAR(200) | NOT NULL |
| action | VARCHAR(50) | NOT NULL (advance/approve/reject/cancel/timeout) |
| actor_id | UUID | FK→users.id NULL (NULL for system) |
| result | JSONB | NULL (step output data) |
| created_at | TIMESTAMPTZ | NOT NULL |

**Index:** (tenant_id, instance_id, step_index)

### KI-Copilot Tables

#### `ai_conversations`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| role | VARCHAR(20) | NOT NULL (user/assistant) |
| content | TEXT | NOT NULL |
| proposed_actions | JSONB | NULL (array of {method, path, body, description}) |
| executed | BOOLEAN | default false |
| created_at | TIMESTAMPTZ | NOT NULL |

**Index:** (tenant_id, user_id, created_at)

### DMS Plugin Tables (v2 — Plugin Phase)

#### `dms_folders`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(255) | NOT NULL |
| parent_id | UUID | FK→dms_folders.id NULL |
| owner_id | UUID | FK→users.id |
| path | VARCHAR(1000) | NOT NULL (materialized path) |
| deleted_at | TIMESTAMPTZ | NULL |
| created_at | TIMESTAMPTZ | NOT NULL |
| updated_at | TIMESTAMPTZ | NOT NULL |

**Index:** (tenant_id, parent_id), (tenant_id, path)

#### `dms_files`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(255) | NOT NULL |
| folder_id | UUID | FK→dms_folders.id NULL |
| size | BIGINT | NOT NULL |
| mime_type | VARCHAR(100) | NOT NULL |
| storage_path | VARCHAR(1000) | NOT NULL |
| uploaded_by | UUID | FK→users.id |
| uploaded_at | TIMESTAMPTZ | NOT NULL |
| modified_at | TIMESTAMPTZ | NOT NULL |
| deleted_at | TIMESTAMPTZ | NULL |

**Index:** (tenant_id, folder_id), (tenant_id, deleted_at)

#### `file_links`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| file_id | UUID | FK→dms_files.id |
| entity_type | VARCHAR(50) | NOT NULL (company/contact) |
| entity_id | UUID | NOT NULL |

**Unique:** (file_id, entity_type, entity_id)

#### `tags`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(100) | NOT NULL |
| color | VARCHAR(7) | default '#808080' |
| created_at | TIMESTAMPTZ | NOT NULL |

**Unique:** (tenant_id, name)

#### `tag_assignments`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| entity_type | VARCHAR(50) | NOT NULL |
| entity_id | UUID | NOT NULL |
| tag_id | UUID | FK→tags.id |

**Unique:** (entity_type, entity_id, tag_id)

#### `folder_permissions`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| folder_id | UUID | FK→dms_folders.id |
| group_id | UUID | NULL |
| user_id | UUID | NULL |
| permission | VARCHAR(10) | NOT NULL (read/write/admin) |

#### `file_shares`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| file_id | UUID | FK→dms_files.id |
| user_id | UUID | NULL |
| group_id | UUID | NULL |
| permission | VARCHAR(10) | NOT NULL (read/write) |

#### `share_links`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| file_id | UUID | FK→dms_files.id |
| token | VARCHAR(64) | NOT NULL UNIQUE |
| password_hash | VARCHAR(255) | NULL |
| expires_at | TIMESTAMPTZ | NULL |
| download_only | BOOLEAN | default false |

### Calendar Plugin Tables (v2 — Plugin Phase)

#### `calendars`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(200) | NOT NULL |
| color | VARCHAR(7) | default '#3B82F6' |
| type | VARCHAR(20) | NOT NULL (personal/team/project/company) |
| owner_id | UUID | FK→users.id |
| created_at | TIMESTAMPTZ | NOT NULL |

#### `calendar_entries`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| calendar_id | UUID | FK→calendars.id |
| entry_type | VARCHAR(15) | NOT NULL (appointment/task) |
| subtype | VARCHAR(20) | default 'normal' (normal/follow_up/private) |
| title | VARCHAR(500) | NOT NULL |
| description | TEXT | NULL |
| start_at | TIMESTAMPTZ | NULL (appointment) |
| end_at | TIMESTAMPTZ | NULL (appointment) |
| all_day | BOOLEAN | default false |
| location | VARCHAR(500) | NULL |
| due_date | TIMESTAMPTZ | NULL (task) |
| priority | VARCHAR(10) | NULL (high/medium/low) (task) |
| status | VARCHAR(20) | default 'open' (open/in_progress/done/cancelled) |
| assigned_to | UUID | FK→users.id NULL (task) |
| reminder | JSONB | NULL ({value, unit, channel}) |
| recurrence | JSONB | NULL ({pattern, custom_rule, end_date, exceptions}) |
| source_mail_id | UUID | NULL (mail integration) |
| created_at | TIMESTAMPTZ | NOT NULL |
| updated_at | TIMESTAMPTZ | NOT NULL |
| deleted_at | TIMESTAMPTZ | NULL |

**Index:** (tenant_id, calendar_id), (tenant_id, start_at), (tenant_id, due_date), (tenant_id, assigned_to, status)

#### `calendar_entry_links`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| entry_id | UUID | FK→calendar_entries.id |
| entity_type | VARCHAR(50) | NOT NULL (company/contact) |
| entity_id | UUID | NOT NULL |

#### `calendar_shares`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| calendar_id | UUID | FK→calendars.id |
| user_id | UUID | NULL |
| group_id | UUID | NULL |
| permission | VARCHAR(10) | NOT NULL (read/write) |

#### `user_calendar_visibility`
| Column | Type | Constraints |
|--------|------|-------------|
| user_id | UUID | FK→users.id |
| calendar_id | UUID | FK→calendars.id |
| tenant_id | UUID | FK→tenants.id |
| visible | BOOLEAN | default true |

**PK:** (user_id, calendar_id)

#### `subtasks`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| entry_id | UUID | FK→calendar_entries.id |
| title | VARCHAR(500) | NOT NULL |
| completed | BOOLEAN | default false |
| created_at | TIMESTAMPTZ | NOT NULL |

#### `resources`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(200) | NOT NULL |
| type | VARCHAR(50) | NOT NULL (room/equipment) |

#### `resource_bookings`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| resource_id | UUID | FK→resources.id |
| entry_id | UUID | FK→calendar_entries.id |
| start_at | TIMESTAMPTZ | NOT NULL |
| end_at | TIMESTAMPTZ | NOT NULL |

### Mail Plugin Tables (v2 — Plugin Phase)

#### `mail_accounts`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| name | VARCHAR(200) | NOT NULL |
| type | VARCHAR(20) | default 'personal' (personal/shared) |
| imap_host | VARCHAR(255) | NOT NULL |
| imap_port | INTEGER | NOT NULL |
| imap_ssl | BOOLEAN | default true |
| smtp_host | VARCHAR(255) | NOT NULL |
| smtp_port | INTEGER | NOT NULL |
| smtp_starttls | BOOLEAN | default true |
| username | VARCHAR(255) | NOT NULL |
| password_encrypted | BYTEA | NOT NULL (AES-256) |
| default_signature_id | UUID | NULL |

#### `mail_folders`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| account_id | UUID | FK→mail_accounts.id |
| name | VARCHAR(200) | NOT NULL |
| type | VARCHAR(20) | NOT NULL (inbox/sent/drafts/spam/custom) |
| parent_id | UUID | FK→mail_folders.id NULL |
| unread_count | INTEGER | default 0 |
| total_count | INTEGER | default 0 |

#### `mails`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| account_id | UUID | FK→mail_accounts.id |
| folder_id | UUID | FK→mail_folders.id |
| subject | TEXT | NULL |
| body_html | TEXT | NULL (sanitized with DOMPurify) |
| body_text | TEXT | NULL |
| from_addr | VARCHAR(255) | NOT NULL |
| to_addrs | JSONB | NOT NULL (array) |
| cc_addrs | JSONB | NULL |
| bcc_addrs | JSONB | NULL |
| date | TIMESTAMPTZ | NOT NULL |
| in_reply_to | VARCHAR(255) | NULL |
| references | TEXT | NULL |
| thread_id | VARCHAR(255) | NULL |
| seen | BOOLEAN | default false |
| flagged | BOOLEAN | default false |
| has_attachments | BOOLEAN | default false |
| body_tsv | TSVECTOR | NULL (full-text search) |

**Index:** GIN(body_tsv), (tenant_id, account_id, folder_id), (tenant_id, thread_id)

#### `mail_attachments`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| mail_id | UUID | FK→mails.id |
| filename | VARCHAR(255) | NOT NULL |
| mime_type | VARCHAR(100) | NOT NULL |
| size | BIGINT | NOT NULL |
| dms_file_id | UUID | FK→dms_files.id NULL |
| content_id | VARCHAR(255) | NULL (inline images) |

#### `mail_labels`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(100) | NOT NULL |
| color | VARCHAR(7) | NOT NULL |

#### `mail_label_assignments`
| Column | Type | Constraints |
|--------|------|-------------|
| mail_id | UUID | FK→mails.id |
| label_id | UUID | FK→mail_labels.id |
| tenant_id | UUID | FK→tenants.id |

**PK:** (mail_id, label_id)

#### `mail_rules`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| account_id | UUID | FK→mail_accounts.id |
| name | VARCHAR(200) | NOT NULL |
| conditions | JSONB | NOT NULL |
| actions | JSONB | NOT NULL |
| priority | INTEGER | default 0 |

#### `mail_templates`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id NULL (NULL=shared) |
| name | VARCHAR(200) | NOT NULL |
| subject | VARCHAR(500) | NULL |
| body_html | TEXT | NOT NULL |

#### `mail_signatures`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| name | VARCHAR(200) | NOT NULL |
| body_html | TEXT | NOT NULL |

#### `vacation_sent_log`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| account_id | UUID | FK→mail_accounts.id |
| sender_address | VARCHAR(255) | NOT NULL |
| sent_at | TIMESTAMPTZ | NOT NULL |

#### `mail_seen_by`
| Column | Type | Constraints |
|--------|------|-------------|
| mail_id | UUID | FK→mails.id |
| user_id | UUID | FK→users.id |
| seen_at | TIMESTAMPTZ | NOT NULL |

**PK:** (mail_id, user_id)

#### `mail_account_delegates`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| account_id | UUID | FK→mail_accounts.id |
| delegate_user_id | UUID | FK→users.id |
| permission | VARCHAR(10) | NOT NULL (read/full) |

#### `mail_account_send_permissions`
| Column | Type | Constraints |
|--------|------|-------------|
| account_id | UUID | FK→mail_accounts.id |
| user_id | UUID | FK→users.id |

**PK:** (account_id, user_id)

#### `pgp_keys`
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| private_key_encrypted | BYTEA | NULL |
| public_key | TEXT | NOT NULL |

#### `contact_pgp_keys`
| Column | Type | Constraints |
|--------|------|-------------|
| contact_id | UUID | FK→contacts.id |
| public_key | TEXT | NOT NULL |
| tenant_id | UUID | FK→tenants.id |

**PK:** (contact_id)

### Full-Text Search

PostgreSQL `tsvector` with GIN index on:
- `contacts`: `to_tsvector('simple', last_name || ' ' || first_name || ' ' || COALESCE(email, ''))`
- `companies`: `to_tsvector('simple', name || ' ' || COALESCE(description, '') || ' ' || COALESCE(billing_city, ''))`
- `mails`: `to_tsvector('simple', subject || ' ' || body_text)` stored in `body_tsv` column

---

## 3. API Design

### Conventions

- **Versioning:** URL-based: `/api/v1/...`
- **Auth:** Session cookie (HttpOnly, Secure, SameSite=Strict). All endpoints except `/api/v1/health` and `/api/v1/auth/*` require auth.
- **Tenant Context:** Active tenant stored in session. All API responses are tenant-scoped.
- **Error Format:** `{"detail": "message", "code": "error_code", "fields": {"field": "msg"}}`
- **Pagination:** `?page=1&page_size=25` → `{items: [...], total: N, page: P, page_size: S}`
- **Sort:** `?sort_by=name&sort_order=asc|desc`
- **Search:** `?search=text` → full-text search
- **Filter:** `?industry=IT&country=Germany` → structured filters
- **Export:** `?format=csv|xlsx` on list endpoints
- **CSRF:** SameSite=Strict + Origin-Header-Validierung (no double-submit token)

### Auth Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| POST | `/api/v1/auth/login` | F-AUTH-01 | Login with email+password, sets session cookie |
| POST | `/api/v1/auth/logout` | F-AUTH-02 | Invalidate session, clear cookie |
| GET | `/api/v1/auth/me` | F-AUTH-01 | Get current user + active tenant |
| POST | `/api/v1/auth/switch-tenant` | F-AUTH-07 | Switch active tenant |
| POST | `/api/v1/auth/password-reset/request` | F-AUTH-05 | Request password reset email |
| POST | `/api/v1/auth/password-reset/confirm` | F-AUTH-05 | Reset password with token |

### User Management Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/users` | F-AUTH-03 | List users (admin only, paginated) |
| POST | `/api/v1/users` | F-AUTH-03 | Create user (admin only) |
| GET | `/api/v1/users/{id}` | F-AUTH-03 | Get user details |
| PATCH | `/api/v1/users/{id}` | F-AUTH-03 | Update user |
| DELETE | `/api/v1/users/{id}` | F-AUTH-03 | Delete user |
| GET | `/api/v1/users/me/settings` | F-CORE-09 | Get current user preferences |
| PATCH | `/api/v1/users/me/settings` | F-CORE-09 | Update preferences (language, theme, etc.) |

### Role Management Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/roles` | F-AUTH-06 | List roles |
| POST | `/api/v1/roles` | F-AUTH-06 | Create role |
| PATCH | `/api/v1/roles/{id}` | F-AUTH-06 | Update role (incl. field permissions) |
| DELETE | `/api/v1/roles/{id}` | F-AUTH-06 | Delete role |

### Tenant Management Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/tenants` | F-AUTH-07 | List tenants for current user |
| POST | `/api/v1/tenants` | F-AUTH-07 | Create tenant (admin) |
| GET | `/api/v1/tenants/{id}/users` | F-AUTH-07 | List users in tenant |
| POST | `/api/v1/tenants/{id}/users` | F-AUTH-07 | Assign user to tenant |

### Company Endpoints (F-DATA-01, F-DATA-02)

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/companies` | F-COMP-05,06 | List with search, filter, pagination, sort |
| POST | `/api/v1/companies` | F-COMP-01 | Create company |
| GET | `/api/v1/companies/{id}` | F-COMP-02 | Get company detail (incl. contacts) |
| PUT | `/api/v1/companies/{id}` | F-COMP-03 | Update company |
| DELETE | `/api/v1/companies/{id}` | F-COMP-04 | Soft-delete (?cascade=true) |
| POST | `/api/v1/companies/{id}/contacts/{contact_id}` | F-CONT-07 | Add N:M contact link |
| DELETE | `/api/v1/companies/{id}/contacts/{contact_id}` | F-CONT-07 | Remove N:M contact link |
| GET | `/api/v1/companies/export` | F-DATA-01,02 | Export (?format=csv|xlsx) |
| GET | `/api/v1/companies/{id}/emails` | F-MAIL-10 | Company email history |

### Contact Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/contacts` | F-CONT-05,06 | List with search, filter, pagination |
| POST | `/api/v1/contacts` | F-CONT-01 | Create contact (with company_ids array) |
| GET | `/api/v1/contacts/{id}` | F-CONT-02 | Get contact detail (incl. companies) |
| PUT | `/api/v1/contacts/{id}` | F-CONT-03 | Update contact |
| DELETE | `/api/v1/contacts/{id}` | F-CONT-04 | Soft-delete |
| DELETE | `/api/v1/contacts/{id}?gdpr=true` | F-COMP-08 | Hard delete (DSGVO) |
| GET | `/api/v1/contacts/export` | F-DATA-01,02 | Export (?format=csv|xlsx) |
| GET | `/api/v1/contacts/{id}/emails` | F-MAIL-10 | Contact email history |

### Import Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| POST | `/api/v1/import` | F-MIG-01 | CSV import (entity_type + file) |
| POST | `/api/v1/import/preview` | F-CORE-11 | Dry-run import preview |

### Audit Log Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/audit-log` | F-COMP-07 | List audit log (admin, paginated) |

### Notification Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/notifications` | F-CORE-13 | List notifications (unread first) |
| PATCH | `/api/v1/notifications/{id}/read` | F-CORE-13 | Mark as read |
| GET | `/api/v1/notifications/unread-count` | F-CORE-13 | Unread badge count |
| PATCH | `/api/v1/users/me/notification-prefs` | F-CORE-13 | Update notification preferences |

### Global Search Endpoint (F-COMP-06, F-CONT-06, F-SEARCH-01)

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/search?q=text` | F-SEARCH-01 | Search across all entities |

### Health & Infrastructure

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/health` | F-INFRA-01 | Health check (no auth) |
| GET | `/api/v1/jobs/{id}/status` | F-SCHED-01 | Background job status |

### Plugin System Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/plugins` | F-PLUGIN-01 | List plugins (status) |
| POST | `/api/v1/plugins/{name}/install` | F-PLUGIN-02 | Install plugin |
| POST | `/api/v1/plugins/{name}/activate` | F-PLUGIN-02 | Activate plugin |
| POST | `/api/v1/plugins/{name}/deactivate` | F-PLUGIN-02 | Deactivate plugin |
| DELETE | `/api/v1/plugins/{name}` | F-PLUGIN-02 | Uninstall (?remove_data=true) |
| GET | `/api/v1/plugins/manifest` | F-PLUGIN-02 | Plugin manifest schema (for developers) |

### DMS Plugin Endpoints (v2 — Plugin Phase)

> **v2 Plugin Features** — These endpoints are implemented in T04 (DMS Backend) and T08a (DMS Frontend). Not available in v1.

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/dms/folders` | F-FILEUI-01 | List folders (tree) |
| POST | `/api/v1/dms/folders` | F-DMS-01 | Create folder |
| PATCH | `/api/v1/dms/folders/{id}` | F-DMS-01 | Rename/move folder |
| DELETE | `/api/v1/dms/folders/{id}` | F-DMS-01 | Soft-delete folder |
| POST | `/api/v1/dms/files/upload` | F-DMS-02 | Upload file (multipart) |
| GET | `/api/v1/dms/files/{id}` | F-DMS-06 | File metadata |
| PATCH | `/api/v1/dms/files/{id}` | F-DMS-03 | Rename/move file |
| DELETE | `/api/v1/dms/files/{id}` | F-DMS-03 | Soft-delete file |
| POST | `/api/v1/dms/files/{id}/restore` | F-DMS-03 | Restore from trash |
| GET | `/api/v1/dms/files/{id}/preview` | F-DMS-04 | PDF preview stream |
| POST | `/api/v1/dms/files/{id}/edit-session` | F-DMS-05 | OnlyOffice edit session |
| GET | `/api/v1/dms/files/{id}/permissions` | F-PERM-06 | Permission overview |
| POST | `/api/v1/dms/files/{id}/link` | F-LINK-01,02 | Link to entity |
| DELETE | `/api/v1/dms/files/{id}/link` | F-LINK-05 | Remove entity link |
| POST | `/api/v1/dms/files/{id}/share` | F-PERM-03,04 | Share with user/group |
| DELETE | `/api/v1/dms/files/{id}/share` | F-PERM-03,04 | Remove share |
| POST | `/api/v1/dms/files/{id}/share-link` | F-PERM-05 | Create public share link |
| GET | `/api/v1/dms/search` | F-DMS-07 | Search files (?folder_id) |
| GET | `/api/v1/dms/shared-with-me` | F-PERM-03 | Shared files list |
| POST | `/api/v1/dms/files/bulk-move` | F-FILEUI-04 | Bulk move |
| POST | `/api/v1/dms/files/bulk-delete` | F-FILEUI-04 | Bulk delete |

### Tag Plugin Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/tags` | F-TAG-04 | List tags (with counts) |
| POST | `/api/v1/tags` | F-TAG-02 | Create tag (admin) |
| PATCH | `/api/v1/tags/{id}` | F-TAG-02 | Update tag |
| DELETE | `/api/v1/tags/{id}` | F-TAG-02 | Delete tag (cascade) |
| POST | `/api/v1/tags/assign` | F-TAG-01 | Assign tag to entity |
| DELETE | `/api/v1/tags/assign` | F-TAG-01 | Remove tag from entity |
| POST | `/api/v1/tags/bulk-assign` | F-FILEUI-04 | Bulk tag assign |

### Calendar Plugin Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/calendars` | F-CAL-11 | List calendars |
| POST | `/api/v1/calendars` | F-CAL-11 | Create calendar |
| PATCH | `/api/v1/calendars/{id}` | F-CAL-11 | Update calendar |
| DELETE | `/api/v1/calendars/{id}` | F-CAL-11 | Delete calendar (cascade) |
| POST | `/api/v1/calendars/{id}/share` | F-CAL-13 | Share calendar |
| GET | `/api/v1/calendars/{id}/permissions` | F-CAL-13 | Calendar permissions |
| GET | `/api/v1/calendar/entries` | F-CAL-01,17 | List entries (filter, paginate) |
| POST | `/api/v1/calendar/entries` | F-CAL-03 | Create entry (appointment/task) |
| GET | `/api/v1/calendar/entries/{id}` | F-CAL-03 | Get entry detail |
| PATCH | `/api/v1/calendar/entries/{id}` | F-CAL-05 | Update entry (drag&drop, status) |
| DELETE | `/api/v1/calendar/entries/{id}` | — | Delete entry |
| POST | `/api/v1/calendar/entries/{id}/link` | F-CAL-04 | Link to entity |
| POST | `/api/v1/calendar/entries/{id}/subtasks` | F-CAL-16 | Create subtask |
| PATCH | `/api/v1/calendar/entries/{id}/subtasks/{sub_id}` | F-CAL-16 | Toggle subtask |
| POST | `/api/v1/calendar/entries/bulk` | F-CAL-18 | Bulk actions |
| GET | `/api/v1/calendar/kanban` | F-CAL-02 | Kanban board view |
| GET | `/api/v1/calendar/entries/export` | F-CAL-17 | Export tasks CSV |
| GET | `/api/v1/calendar/{calendar_id}/ics-feed` | F-CAL-09 | ICS feed export |
| POST | `/api/v1/calendar/import` | F-CAL-09 | ICS import |
| POST | `/api/v1/resources` | F-CAL-10 | Create resource (admin) |
| POST | `/api/v1/calendar/entries/{id}/book-resource` | F-CAL-10 | Book resource |

### Mail Plugin Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/mail/accounts` | F-MAIL-14 | List mail accounts |
| POST | `/api/v1/mail/accounts` | F-MAIL-18 | Create mail account |
| PATCH | `/api/v1/mail/accounts/{id}` | F-MAIL-14 | Update account |
| GET | `/api/v1/mail/accounts/shared` | F-MAIL-15 | Shared mailboxes |
| POST | `/api/v1/mail/accounts/{id}/users` | F-MAIL-15 | Assign shared mailbox users |
| POST | `/api/v1/mail/accounts/{id}/delegates` | F-MAIL-16 | Delegate access |
| POST | `/api/v1/mail/accounts/{id}/send-permissions` | F-MAIL-17 | Grant send permission |
| GET | `/api/v1/mail/folders` | F-MAIL-01,19 | List mail folders |
| POST | `/api/v1/mail/folders` | F-MAIL-19 | Create folder |
| PATCH | `/api/v1/mail/folders/{id}` | F-MAIL-19 | Rename folder |
| DELETE | `/api/v1/mail/folders/{id}` | F-MAIL-19 | Delete folder |
| GET | `/api/v1/mail` | F-MAIL-03 | List mails (filter, search, paginate) |
| GET | `/api/v1/mail/{id}` | F-MAIL-02 | Get mail detail |
| POST | `/api/v1/mail/send` | F-MAIL-02 | Send mail |
| POST | `/api/v1/mail/{id}/reply` | F-MAIL-02 | Reply to mail |
| POST | `/api/v1/mail/{id}/forward` | F-MAIL-02 | Forward mail |
| PATCH | `/api/v1/mail/{id}/flags` | F-MAIL-09 | Update flags (seen/flagged) |
| GET | `/api/v1/mail/{id}/attachments/{att_id}` | F-MAIL-04 | Download attachment |
| POST | `/api/mail/{id}/link` | F-MAIL-10 | Manual contact/company link |
| POST | `/api/v1/mail/{id}/create-event` | F-MAIL-11 | Create calendar event from mail |
| GET | `/api/v1/mail/search` | F-MAIL-03 | Full-text mail search |
| GET | `/api/v1/mail/threads` | F-MAIL-05 | Threaded view |
| POST | `/api/v1/mail/templates` | F-MAIL-06 | Create template |
| GET | `/api/v1/mail/templates` | F-MAIL-06 | List templates |
| POST | `/api/v1/mail/signatures` | F-MAIL-13 | Create signature |
| GET | `/api/v1/mail/signatures` | F-MAIL-13 | List signatures |
| POST | `/api/v1/mail/rules` | F-MAIL-07 | Create mail rule |
| GET | `/api/v1/mail/rules` | F-MAIL-07 | List rules |
| DELETE | `/api/v1/mail/rules/{id}` | F-MAIL-07 | Delete rule |
| POST | `/api/v1/mail/vacation` | F-MAIL-08 | Set vacation auto-reply |
| POST | `/api/v1/mail/pgp/keys` | F-MAIL-12 | Import PGP private key |
| POST | `/api/v1/contacts/{id}/pgp-key` | F-MAIL-12 | Import contact public key |
| POST | `/api/v1/mail/labels` | F-MAIL-09 | Create label |
| POST | `/api/v1/mail/{id}/labels` | F-MAIL-09 | Assign label to mail |

### Public Endpoints (no auth)

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/health` | F-INFRA-01 | Health check |
| GET | `/api/public/share/{token}` | F-PERM-05 | Public share link access |
| GET | `/api/v1/calendar/{calendar_id}/ics-feed?token=...` | F-CAL-09 | ICS feed (token auth) |

### KI-Copilot Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| POST | `/api/v1/ai/copilot/query` | F-AI-01 | Natural language → proposed API calls |
| GET | `/api/v1/ai/copilot/history` | F-AI-01 | Conversation history (per user, paginated) |
| POST | `/api/v1/ai/copilot/execute` | F-AI-01 | Execute proposed API action (with user confirmation) |

### Workflow Engine Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/workflows` | F-WF-01 | List workflow definitions (paginated, filter by entity_type) |
| POST | `/api/v1/workflows` | F-WF-01 | Create workflow definition (admin only) |
| GET | `/api/v1/workflows/{id}` | F-WF-01 | Get workflow definition detail |
| PATCH | `/api/v1/workflows/{id}` | F-WF-01 | Update workflow definition |
| DELETE | `/api/v1/workflows/{id}` | F-WF-01 | Delete workflow definition |
| POST | `/api/v1/workflows/{id}/instances` | F-WF-01 | Start workflow instance (trigger) |
| GET | `/api/v1/workflows/instances` | F-WF-01 | List workflow instances (filter by status, paginated) |
| GET | `/api/v1/workflows/instances/{id}` | F-WF-01 | Get instance detail (current step, history) |
| POST | `/api/v1/workflows/instances/{id}/advance` | F-WF-01 | Advance to next step (approve/reject) |
| POST | `/api/v1/workflows/instances/{id}/cancel` | F-WF-01 | Cancel workflow instance |

### Monitoring Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/health` | F-INFRA-01,F-INFRA-04 | Extended health check (DB, Redis, storage, worker) |
| GET | `/api/v1/metrics` | F-INFRA-04 | Prometheus metrics (admin only) |

---

## 4. Plugin Architecture

### Plugin Manifest Format

```json
{
  "name": "dms",
  "version": "1.0.0",
  "display_name": "Dateien (DMS)",
  "description": "Datei-Management-System mit Ordnerstruktur, Upload, OnlyOffice",
  "author": "LeoCRM Team",
  "dependencies": [],
  "min_core_version": "1.0.0",
  "services": ["db", "cache", "event_bus", "storage", "notifications"],
  "endpoints": {
    "router": "app.plugins.builtins.dms.router:router"
  },
  "migrations": {
    "package": "app.plugins.builtins.dms.migrations",
    "versions_dir": "migrations"
  },
  "ui": {
    "routes": [{"path": "/dms", "component": "DmsView"}],
    "menu_items": [{"label": "Dateien", "icon": "folder", "route": "/dms", "order": 40}],
    "detail_tabs": [
      {"entity": "company", "tab_id": "files", "label": "Dateien", "component": "CompanyFilesTab"},
      {"entity": "contact", "tab_id": "files", "label": "Dateien", "component": "ContactFilesTab"}
    ],
    "settings_pages": [{"id": "dms-settings", "label": "DMS-Einstellungen", "component": "DmsSettings"}],
    "dashboard_widgets": []
  },
  "events": {
    "listens_to": ["company.deleted", "contact.deleted"],
    "emits": ["dms.file.uploaded", "dms.file.shared"]
  },
  "preferences": [
    {"key": "default_folder_view", "type": "string", "default": "grid", "options": ["grid", "list"]}
  ],
  "notification_types": ["dms.share_received", "dms.upload_complete"]
}
```

### Lifecycle Hooks

```
install()   → Run DB migrations, register plugin in DB (status=installed)
activate()  → Register routes, event listeners, UI components (status=active)
deactivate()→ Unregister routes, event listeners, UI components (status=inactive)
uninstall() → Optional: drop plugin tables (?remove_data=true, status=removed)
```

### Event Bus (F-CORE-01)

> **v1 Core Feature** — Event Bus is part of T01 (Core Infrastructure).

```python
# Publishing events
await event_bus.publish("company.created", payload={"company_id": uuid, "tenant_id": uuid})
await event_bus.publish("contact.deleted", payload={"contact_id": uuid, "tenant_id": uuid})

# Subscribing (plugins register during activate())
@event_bus.subscribe("company.created")
async def on_company_created(event):
    # e.g., create default folder for company
    ...
``

**Implementation:** Async in-process event bus. Events are dispatched to registered handlers. For persistence/retry, events are also pushed to Redis job queue for reliable processing.

### Service Container / DI (F-CORE-05, F-CORE-07, F-CORE-08, F-CORE-10, F-CORE-12)

> **v1 Core Features:**
> - F-CORE-07: Async Job Queue (ARQ) — background jobs for export, backup, mail sync
> - F-CORE-08: Caching-Strategie — Redis-based caching for sessions, query results, plugin metadata
> - F-CORE-10: Storage-Backend — abstract storage interface (local filesystem, S3-compatible)
> - F-CORE-12: PDF/Document Generation Service — WeasyPrint for PDF generation (export, reports)

```python
# Core services registered in container
class ServiceContainer:
    db: SessionManager
    cache: RedisCache
    event_bus: EventBus
    storage: StorageBackend
    notifications: NotificationService
    audit: AuditLogger
    jobs: JobQueue

# Plugin requests services via manifest
def activate(container: ServiceContainer):
    db = container.db
    event_bus = container.event_bus
    ...
```

### Plugin DB Migration (F-CORE-03)

Each plugin has its own `migrations/` directory with versioned SQL/Python files. Migrations are tracked in a `plugin_migrations` table:

| Column | Type |
|--------|------|
| plugin_name | VARCHAR |
| migration_id | VARCHAR |
| executed_at | TIMESTAMPTZ |

All plugin tables include `tenant_id` column for isolation.

### UI Plugin Framework (F-CORE-04)

The backend plugin manifest declares UI components. The frontend `PluginRegistry.tsx` fetches active plugin manifests on startup and dynamically renders:
- Routes (React Router)
- Menu items (Sidebar)
- Detail tabs (Company/Contact detail views)
- Settings pages (Settings tree)
- Dashboard widgets

Plugin UI components are lazy-loaded via `React.lazy()` with Suspense boundaries.

---

## 5. Multi-Tenant Architecture

### Implementation (F-CORE-02)

1. **Session Context:** Active `tenant_id` stored in session. Set at login (default tenant) or via `switch-tenant`.

2. **ORM Auto-Filtering:** SQLAlchemy `before_query` event listener automatically injects `tenant_id` filter on all models that have a `tenant_id` column. This prevents cross-tenant data access at the ORM level.

```python
@event.listens_for(Session, "do_orm_execute")
def auto_filter_tenant(execute_state):
    if not _tenant_filter_disabled:
        execute_state.statement = execute_state.statement.where(
            TenantMixin.tenant_id == current_tenant_id()
        )
```

3. **TenantMixin:** All models with tenant isolation inherit from a `TenantMixin` base class that adds `tenant_id` column.

4. **Tenant Switch:** `POST /api/v1/auth/switch-tenant` updates session. All subsequent queries use new tenant_id.

5. **Cross-Tenant Protection:** If a user tries to access a resource not in their active tenant → 404 (not 403, to prevent information leakage).

6. **Plugin Tables:** All plugin-created tables MUST include `tenant_id`. The plugin migration validator checks this.

---

## 6. Auth Architecture

### Session-Based Auth (F-AUTH-01, F-INT-02)

```
Login Flow:
1. POST /api/v1/auth/login {email, password}
2. Backend validates → bcrypt.check_password(password, user.password_hash)
3. Create session in Redis (key: `session:{session_id}`, value: {user_id, tenant_id, csrf_token}, TTL=8h)
4. Write session record to PostgreSQL `sessions` table for audit trail (id, user_id, tenant_id, csrf_token, expires_at, created_at)
5. Set cookie: leocrm_session=<session_id>; HttpOnly; Secure; SameSite=Strict; Path=/
6. Return {user, tenant} info
```

### RBAC (F-AUTH-04, F-AUTH-06, F-AUTH-08)

```
Role → Permissions Structure:
{
  "companies": {"read": true, "write": true, "delete": true, "admin": false},
  "contacts": {"read": true, "write": true, "delete": true, "admin": false},
  "users": {"read": false, "write": false, "delete": false, "admin": false},
  ...
}

Field-Level Permissions:
{
  "companies.annual_revenue": "hidden",  // viewer can't see
  "companies.phone": "read_only",       // editor can't edit
  "contacts.email": "read_write"         // full access
}
```

Default roles: `admin` (all permissions), `editor` (CRUD on companies/contacts, no user management), `viewer` (read-only).

Custom roles can be created via `POST /api/v1/roles` with custom permissions.

### API Tokens (F-INT-02)

API tokens for external integrations (post-MVP, but architecture supports it):
- Tokens stored in `api_tokens` table (user_id, token_hash, name, scopes, expires_at)
- Token auth via `Authorization: Bearer <token>` header
- Token respects RBAC and tenant isolation

### CSRF Protection (F-SEC-01, F-SEC-03)

> **v1 Core Feature** — CSRF protection via SameSite=Strict + Origin validation.

- SameSite=Strict cookie (browser blocks cross-site requests)
- Origin-Header-Validierung middleware (server-side check)
- Only GET/HEAD/OPTIONS are exempt

### Content-Security-Policy (F-SEC-02)

- **CSP-Header** gesetzt im Nginx-Reverse-Proxy für alle Responses:
  `Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob:; font-src 'self' data:; connect-src 'self'; frame-src 'self' https://onlyoffice:8080; object-src 'none'; base-uri 'self'; form-action 'self'`
- **X-Content-Type-Options:** `nosniff`
- **X-Frame-Options:** `SAMEORIGIN` (nur OnlyOffice iframe erlaubt)
- **X-XSS-Protection:** `1; mode=block`
- **Strict-Transport-Security:** `max-age=31536000; includeSubDomains`
- **Referrer-Policy:** `strict-origin-when-cross-origin`
- HTML in User-Eingaben wird serverseitig via Pydantic validiert und im Frontend via DOMPurify/escaped rendering sanitized

### CORS Configuration

> **v1 Core Feature** — Cross-Origin Resource Sharing policy for API security.

- **Production:** Same-origin only (`Access-Control-Allow-Origin: <self>`). Frontend and API served from same domain via Nginx reverse proxy.
- **Development:** Explicit origins allowed: `http://localhost:5173` (Vite dev), `http://localhost:3000` (alt dev). No wildcard `*`.
- **Methods:** `GET, POST, PATCH, PUT, DELETE, OPTIONS`
- **Headers:** `Authorization, Content-Type, X-CSRF-Token, X-Tenant-ID`
- **Credentials:** `true` (cookies allowed for session auth)
- **Max-Age:** `3600` (preflight cache)
- **Implementation:** FastAPI `CORSMiddleware` with explicit origin list, not wildcard.

### Auth Rate Limiting (Brute-Force Protection)

> **v1 Core Feature** — Rate limiting for authentication endpoints to prevent brute-force attacks.

- **Login endpoint** (`POST /api/v1/auth/login`):
  - Redis-based counter: `auth:login:{ip}:{email}` with TTL=15min
  - Max 5 failed attempts per 15min window → 429 Too Many Requests
  - On success: counter reset
  - On failure: counter incremented, response includes `Retry-After` header
- **Password reset request** (`POST /api/v1/auth/password-reset/request`):
  - Redis-based counter: `auth:reset:{ip}` with TTL=1h
  - Max 3 requests per hour → 429 (prevents email enumeration via timing)
  - Always returns 200 (no user enumeration) but blocks after limit
- **Password reset confirm** (`POST /api/v1/auth/password-reset/confirm`):
  - Redis-based counter: `auth:reset_confirm:{ip}` with TTL=1h
  - Max 5 attempts per hour → 429
- **General API rate limiting** (all endpoints):
  - Redis-based sliding window: `rate:{ip}:{endpoint}` with TTL=1min
  - Default: 60 requests/min per IP per endpoint
  - Auth endpoints: 10 requests/min per IP (stricter)
- **Implementation:** FastAPI middleware using Redis INCR + EXPIRE

### PostgreSQL Row-Level Security (RLS) — Defense-in-Depth

> **v1 Core Feature** — Database-level tenant isolation as defense-in-depth alongside ORM-level tenant filtering.

**Strategy:** ORM-level tenant filtering (SQLAlchemy event listener) is the primary isolation mechanism. PostgreSQL RLS policies provide a secondary defense layer to prevent data leaks if ORM filtering is bypassed (raw SQL, ARQ worker jobs, admin queries).

**Implementation:**

```sql
-- Enable RLS on all tenant-scoped tables
ALTER TABLE companies ENABLE ROW LEVEL SECURITY;
ALTER TABLE contacts ENABLE ROW LEVEL SECURITY;
ALTER TABLE users ENABLE ROW LEVEL SECURITY;
ALTER TABLE roles ENABLE ROW LEVEL SECURITY;
ALTER TABLE sessions ENABLE ROW LEVEL SECURITY;
ALTER TABLE audit_log ENABLE ROW LEVEL SECURITY;
ALTER TABLE notifications ENABLE ROW LEVEL SECURITY;
ALTER TABLE api_tokens ENABLE ROW LEVEL SECURITY;
-- (v2: dms_folders, dms_files, calendars, mail_accounts, etc.)

-- Create policy: users can only see rows in their current tenant
CREATE POLICY tenant_isolation ON companies
  USING (tenant_id = current_setting('app.current_tenant_id')::uuid);

-- Same pattern for all tenant-scoped tables
CREATE POLICY tenant_isolation ON contacts
  USING (tenant_id = current_setting('app.current_tenant_id')::uuid);

-- ... (repeat for all tenant-scoped tables)

-- Application sets tenant context per request:
-- SET LOCAL app.current_tenant_id = '<uuid>';
-- This is set in SQLAlchemy session event listener after tenant resolution
```

**Tenant Context Propagation:**
- **API requests:** SQLAlchemy `before_request` event sets `app.current_tenant_id` session variable
- **ARQ worker jobs:** Job payload includes `tenant_id`; worker sets session variable before processing
- **Raw SQL queries:** Must explicitly set tenant context or use `SET LOCAL`
- **Admin/superuser:** Can bypass RLS via `SET row_security = off` (logged in audit_log)

**Testing:**
- Integration test: create 2 tenants, verify tenant A cannot read tenant B's data even with raw SQL
- Test: ARQ worker processes job with correct tenant context
- Test: RLS bypass attempt is logged in audit_log

### Password Reset (F-AUTH-05, F-INT-01)

> **v1 Core Feature** — F-INT-01: E-Mail-Integration for password reset via SMTP.

```
1. POST /api/v1/auth/password-reset/request {email}
   → Generate token, store hash in `password_reset_tokens` (24h expiry)
   → Send email with reset link
   → Always return 200 (no user enumeration)

2. POST /api/v1/auth/password-reset/confirm {token, new_password}
   → Verify token hash + expiry
   → Update password_hash
   → Mark token as used
   → Invalidate all sessions for user
```

---

## 7. Frontend Architecture

### Stack (F-UI-01, F-UI-02, F-UI-03, F-UI-04, F-UI-05, F-UI-06, F-UI-08)

| Component | Technology |
|-----------|------------|
| Framework | React 18 |
| Build Tool | Vite |
| Router | React Router v6 |
| State (Server) | TanStack Query (React Query v5) |
| State (Client) | Zustand |
| i18n | react-i18next |
| Forms | React Hook Form + Zod |
| Styling | Tailwind CSS |
| Icons | lucide-react |
| Tables | TanStack Table |
| Calendar | Custom (FullCalendar or custom) |
| Rich Text | TipTap (mail composer) |
| PDF Viewer | PDF.js |
| Testing | Vitest + @testing-library/react |

### Routing (F-NAV-01, F-SET-01)

```
/                 → Dashboard
/login            → Login page
/password-reset   → Password reset flow
/companies        → Company list
/companies/:id    → Company detail
/contacts         → Contact list
/contacts/:id     → Contact detail
/calendar         → Calendar (plugin)
/dms              → DMS file browser (plugin)
/mail             → Mail (plugin)
/users            → User management (admin)
/audit-log        → Audit log (admin)
/settings         → Settings tree
/settings/*       → Settings sub-pages
/search           → Global search results
/*                → Plugin routes (dynamic)
```

### State Management

- **TanStack Query:** Server state (API data, caching, optimistic updates, loading/error states).
- **Zustand:** Client state (active tenant, sidebar collapsed, theme, language, UI toggles).
- **URL State:** Filters, pagination, sort via URL search params (shareable URLs).

### i18n

- Locale files: `src/i18n/locales/de.json`, `src/i18n/locales/en.json`
- Default: German. Fallback: German.
- Date/time format via `date-fns` with locale.
- Language stored in user preferences (synced to backend).

### Accessibility (F-A11Y-01, F-A11Y-02, F-A11Y-03)

- Semantic HTML, ARIA roles on all interactive elements.
- `prefers-reduced-motion` media query in global CSS.
- 44px touch targets via Tailwind `min-h-[44px] min-w-[44px]` on buttons/links.
- `.sr-only` class for screen-reader-only text.
- Keyboard navigation: logical tab order, focus visible.
- WCAG 2.1 AA contrast (>4.5:1).

### Design System

Based on the approved prototype (`leocrm-prototype-x7k2p9`):
- Color tokens via Tailwind config
- Component library: Button, Input, Select, Modal, Toast, Table, Card, Badge, Avatar, Pagination, EmptyState, Skeleton
- Responsive breakpoints: `sm: 375px`, `md: 768px`, `lg: 1024px`, `xl: 1280px`

---

## 8. Deployment Architecture

### Docker Compose

```yaml
services:
  backend:
    build: ./backend
    ports: ["8000:8000"]
    env_file: .env
    depends_on: [postgres, redis]
    healthcheck:
      test: curl -f http://localhost:8000/api/v1/health || exit 1
      interval: 30s
      timeout: 10s
      retries: 3

  frontend:
    build: ./frontend
    ports: ["80:80"]
    depends_on: [backend]

  postgres:
    image: postgres:16-alpine
    volumes: ["pgdata:/var/lib/postgresql/data"]
    env_file: .env

  redis:
    image: redis:7-alpine
    volumes: ["redisdata:/data"]

  worker:
    build: ./backend
    command: arq app.core.jobs.WorkerSettings
    env_file: .env
    depends_on: [postgres, redis]

  onlyoffice:
    image: onlyoffice/documentserver:latest
    ports: ["8080:80"]
    volumes: ["onlyoffice_data:/var/www/onlyoffice/Data"]

volumes:
  pgdata:
  redisdata:
  onlyoffice_data:
  storage_data:
```

### Environment Variables (F-ENV-01)

> **v1 Core Feature** — F-ENV-01: Environments & Secrets — dev/test/prod profiles with .env.example.

```env
# Database
POSTGRES_HOST=postgres
POSTGRES_PORT=5432
POSTGRES_DB=leocrm
POSTGRES_USER=leocrm
POSTGRES_PASSWORD=<secret>

# Redis
REDIS_URL=redis://redis:6379/0

# Session
LEOCRM_SECRET_KEY=<min-32-chars>
SESSION_TIMEOUT_HOURS=8

# SMTP (for password reset + mail plugin)
SMTP_HOST=
SMTP_PORT=587
SMTP_USER=
SMTP_PASS=

# Mail encryption key
MAIL_ENCRYPTION_KEY=<32-byte-hex>

# Storage
STORAGE_BACKEND=local  # or s3
STORAGE_PATH=/data/leocrm/storage
S3_ENDPOINT=
S3_BUCKET=
S3_ACCESS_KEY=
S3_SECRET_KEY=

# OnlyOffice
ONLYOFFICE_URL=http://onlyoffice:80

# Logging
LOG_LEVEL=INFO
```

### Backup (F-INFRA-02)

> **v1 Core Feature** — F-INFRA-02: Backup & Restore — pg_dump + file storage backup.

- `pg_dump` daily cron job → backup volume or S3
- Storage volume backup (files)
- Restore documented in `docs/admin-guide.md`

---

## 8b. KI-Integration (F-AI-01)

### Architektur-Grundlage

LeoCRM ist API-First (F-CORE-06): alle Features sind über die REST API nutzbar. Der KI-Copilot nutzt dieselbe API wie das Frontend — er ist ein API-Client mit eigener Authentifizierung.

### KI-Copilot API-Endpoint

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| POST | `/api/v1/ai/copilot/query` | F-AI-01 | Natural language → API call translation |
| GET | `/api/v1/ai/copilot/history` | F-AI-01 | Conversation history (per user) |
| POST | `/api/v1/ai/copilot/execute` | F-AI-01 | Execute proposed API action (with user confirmation) |

### RBAC-Durchsetzung

Der KI-Copilot respektiert das Rollen-/Rechte-System des zugehörigen Users:

1. **Authentifizierung:** Copilot-Requests verwenden die Session des Users (gleicher Cookie). Keine separate Copilot-Auth.
2. **RBAC:** Copilot-API-Calls gehen durch dieselbe RBAC-Middleware wie Frontend-Calls. Ein Viewer-Copilot kann keine Daten löschen.
3. **Field-Level Permissions:** Copilot sieht nur Felder, die die User-Rolle erlaubt (`hidden` fields werden aus Responses gefiltert).
4. **Tenant-Isolation:** Copilot ist an den `tenant_id` der aktiven Session gebunden. Cross-Tenant → 404.
5. **Audit Log:** Alle Copilot-Aktionen werden im Audit-Log als `entity_type=ai_copilot` protokolliert.

### Implementation-Modell (v1)

v1 implementiert die API-Schnittstelle (`/api/v1/ai/copilot/*`) mit:
- **Query-Endpoint:** Nimmt Natural-Language-Input → returns vorgeschlagene API-Calls (Method, Path, Body) + Erklärung
- **Execute-Endpoint:** Führt den vorgeschlagenen API-Call aus (mit User-Bestätigung im Frontend)
- **History:** Speichert Konversationsverlauf pro User
- Die eigentliche LLM-Integration (z.B. OpenAI/Anthropic) ist konfigurierbar via Env-Vars (`AI_MODEL`, `AI_API_KEY`)

### Frontend-Integration

- Sidebar-Eintrag „KI-Copilot" (sichtbar wenn `AI_ENABLED=true`)
- Chat-Interface mit Vorschlags-Karten (zeigt geplante API-Calls vor Ausführung)
- User muss jede destruktive Aktion bestätigen (Confirm-Dialog)

### DB-Tabelle: `ai_conversations`

| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| user_id | UUID | FK→users.id |
| role | VARCHAR(20) | NOT NULL (user/assistant) |
| content | TEXT | NOT NULL |
| proposed_actions | JSONB | NULL (array of {method, path, body, description}) |
| executed | BOOLEAN | default false |
| created_at | TIMESTAMPTZ | NOT NULL |

**Index:** (tenant_id, user_id, created_at)

---

## 8c. Workflow Engine (F-WF-01)

### Hybrid-Ansatz

Zwei Engine-Typen:

1. **Code-Engine (Kern-Workflows):** Hartkodierte Python-Workflows für System-Prozesse (z.B. User-Onboarding, Plugin-Installation-Sequence, Mail-Sync-Trigger). Definiert als `async def` Funktionen im `app/workflows/` Modul. Nicht vom User konfigurierbar.

2. **Configurable Workflow-Engine (User-Workflows):** User-definierte Prozesse via Admin-UI. Mehrstufige Prozesse mit Bedingungen, Genehmigungs-Ketten, Notifications.

### Workflow API Endpoints

| Method | Path | Feature | Description |
|--------|------|---------|-------------|
| GET | `/api/v1/workflows` | F-WF-01 | List workflow definitions |
| POST | `/api/v1/workflows` | F-WF-01 | Create workflow definition (admin) |
| GET | `/api/v1/workflows/{id}` | F-WF-01 | Get workflow definition |
| PATCH | `/api/v1/workflows/{id}` | F-WF-01 | Update workflow definition |
| DELETE | `/api/v1/workflows/{id}` | F-WF-01 | Delete workflow definition |
| POST | `/api/v1/workflows/{id}/instances` | F-WF-01 | Start workflow instance (trigger) |
| GET | `/api/v1/workflows/instances` | F-WF-01 | List workflow instances (filter by status) |
| GET | `/api/v1/workflows/instances/{id}` | F-WF-01 | Get instance detail (current step, history) |
| POST | `/api/v1/workflows/instances/{id}/advance` | F-WF-01 | Advance to next step (approve/reject) |
| POST | `/api/v1/workflows/instances/{id}/cancel` | F-WF-01 | Cancel workflow instance |

### DB-Tabellen

#### `workflows` (Workflow Definition)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| name | VARCHAR(200) | NOT NULL |
| description | TEXT | NULL |
| entity_type | VARCHAR(50) | NOT NULL (company/contact/entry/mail/generic) |
| trigger_type | VARCHAR(30) | NOT NULL (manual/event/schedule) |
| trigger_config | JSONB | NULL (event name or cron expression) |
| steps | JSONB | NOT NULL (ordered array of step definitions) |
| is_active | BOOLEAN | default true |
| created_by | UUID | FK→users.id |
| created_at | TIMESTAMPTZ | NOT NULL |
| updated_at | TIMESTAMPTZ | NOT NULL |

**Index:** (tenant_id, entity_type), (tenant_id, is_active)

**`steps` JSONB Structure:**
```json
[
  {
    "id": "step_1",
    "name": "Angebot erstellen",
    "type": "action",
    "action": "create_entity",
    "entity": "company",
    "fields": {"name": "${trigger.company_name}", "industry": "${trigger.industry}"}
  },
  {
    "id": "step_2",
    "name": "Genehmigung durch Manager",
    "type": "approval",
    "approver_role": "admin",
    "timeout_hours": 48,
    "on_reject": "notify_initiator"
  },
  {
    "id": "step_3",
    "name": "Benachrichtigung senden",
    "type": "notification",
    "template": "offer_approved",
    "recipients": ["initiator"]
  }
]
```

#### `workflow_instances` (Running Workflow)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| workflow_id | UUID | FK→workflows.id |
| entity_type | VARCHAR(50) | NOT NULL |
| entity_id | UUID | NULL |
| current_step_index | INTEGER | NOT NULL default 0 |
| status | VARCHAR(20) | NOT NULL (pending/in_progress/approved/rejected/cancelled/completed) |
| context | JSONB | NOT NULL (trigger data + step results) |
| initiated_by | UUID | FK→users.id |
| created_at | TIMESTAMPTZ | NOT NULL |
| updated_at | TIMESTAMPTZ | NOT NULL |
| completed_at | TIMESTAMPTZ | NULL |

**Index:** (tenant_id, status), (tenant_id, workflow_id), (tenant_id, initiated_by)

#### `workflow_step_history` (Audit Trail per Step)
| Column | Type | Constraints |
|--------|------|-------------|
| id | UUID | PK |
| tenant_id | UUID | FK→tenants.id |
| instance_id | UUID | FK→workflow_instances.id |
| step_index | INTEGER | NOT NULL |
| step_name | VARCHAR(200) | NOT NULL |
| action | VARCHAR(50) | NOT NULL (advance/approve/reject/cancel/timeout) |
| actor_id | UUID | FK→users.id NULL (NULL for system) |
| result | JSONB | NULL (step output data) |
| created_at | TIMESTAMPTZ | NOT NULL |

**Index:** (tenant_id, instance_id, step_index)

### Event Bus Integration

- Workflows mit `trigger_type=event` werden automatisch gestartet, wenn das konfigurierte Event auf dem Event Bus veröffentlicht wird.
- Workflow-Schritte können Events emitten (z.B. `workflow.step_completed`, `workflow.approved`).
- Der Event Bus dispatcht Events an registrierte Workflow-Handler.

### Code-Engine Workflows

Hartkodierte Workflows leben in `app/workflows/code/`:
- `onboarding.py` — User-Onboarding-Sequence (Default-Rolle, Default-Kalender, Welcome-Mail)
- `plugin_sequence.py` — Plugin-Activation-Sequenz (migrations → activate → notify)
- `mail_sync_trigger.py` — Trigger IMAP-Sync beim Account-Setup

Code-Workflows verwenden denselben `workflow_instances` + `workflow_step_history` tables für Audit-Trail.

---

## 8d. Monitoring & Alerting (F-INFRA-04)

### Health Endpoint (erweitert)

`GET /api/v1/health` gibt strukturierten Status zurück:

```json
{
  "status": "healthy",
  "checks": {
    "database": {"status": "up", "latency_ms": 2.3},
    "redis": {"status": "up", "latency_ms": 0.8},
    "storage": {"status": "up"},
    "worker": {"status": "up", "queue_depth": 3}
  },
  "version": "1.0.0",
  "uptime_seconds": 86400
}
}
```

Bei Degradation: `"status": "degraded"` mit betroffenen Checks markiert als `"down"`.

### Prometheus Metrics Endpoint

`GET /api/v1/metrics` (Prometheus format, admin-only auth):
- `leocrm_http_requests_total{method, path, status}` — Request counter
- `leocrm_http_request_duration_seconds{method, path}` — Histogram
- `leocrm_db_pool_connections{state}` — DB pool gauge (idle/used/overflow)
- `leocrm_redis_pool_connections{state}` — Redis pool gauge
- `leocrm_arq_jobs_total{queue, status}` — Job counter
- `leocrm_tenant_active_sessions{tenant_id}` — Active session gauge

### Alerting

- **DB-Connection-Pool erschöpft:** Warning-Alert via structured log (`ALERT: db_pool_exhausted`)
- **App down:** Coolify healthcheck erkennt `status=unhealthy` → Auto-Restart
- **Backup-Fehler:** ARQ job failure → Notification an Admin-User + Error-Log
- **Worker-Queue-Depth > 100:** Warning-Log `ALERT: worker_queue_backlog`
- **Response-Zeit > 2s:** Slow-request-log mit Request-Details

### Structured Logging (F-INFRA-03)

Alle Logs sind JSON-formatiert (`structlog`):
```json
{"timestamp": "2026-06-28T13:00:00Z", "level": "INFO", "event": "http_request", "method": "GET", "path": "/api/v1/companies", "status": 200, "duration_ms": 45, "tenant_id": "...", "user_id": "..."}
```

Log-Level via `LOG_LEVEL` env var (DEBUG/INFO/WARNING/ERROR).

---

## 8e. Performance (F-PERF-01)

### Requirements

- API-Response <500ms für List-Endpunkte bei 200k Datensätzen
- Full-Text-Search <500ms bei 200k Datensätzen
- Frontend: Lazy Loading, Code-Splitting, minimal bundle size

### DB Indexing Strategy

Alle Such- und Filter-Felder haben PostgreSQL-Indizes:

| Table | Index | Type |
|-------|-------|------|
| companies | (tenant_id, name) | B-Tree |
| companies | (tenant_id, industry) | B-Tree |
| companies | (tenant_id, billing_country) | B-Tree |
| companies | (tenant_id, rating) | B-Tree |
| companies | (tenant_id, deleted_at) | B-Tree (partial: WHERE deleted_at IS NULL) |
| contacts | (tenant_id, last_name) | B-Tree |
| contacts | (tenant_id, first_name) | B-Tree |
| contacts | (tenant_id, email) | B-Tree |
| contacts | (tenant_id, deleted_at) | B-Tree (partial) |
| contacts | GIN(tenant_id, body_tsv) | GIN (FTS) |
| mails | GIN(body_tsv) | GIN (FTS) |
| mails | (tenant_id, thread_id) | B-Tree |
| calendar_entries | (tenant_id, start_at) | B-Tree |
| calendar_entries | (tenant_id, due_date) | B-Tree |
| audit_log | (tenant_id, timestamp) | B-Tree |
| audit_log | (tenant_id, entity_type) | B-Tree |

### Query Optimization

- **Pagination:** Default `page_size=25`, max `page_size=100`. Keyset pagination für >10k Ergebnisse (`?cursor=...` statt OFFSET).
- **Eager Loading:** SQLAlchemy `selectinload()` für N:M Beziehungen (vermeidet N+1 Queries).
- **Query Limits:** Alle List-Queries haben `LIMIT` (max 100 rows per page). Full-Table-Scans verboten.
- **Export als Background-Job:** Export >1000 Datensätze → ARQ background job → Notification bei Fertigstellung (F-SCHED-01).
- **Streaming-Response:** CSV-Export streamed via `StreamingResponse` (kein full in-memory load).

### Frontend Performance

- **Code-Splitting:** Route-level `React.lazy()` + `Suspense` (minimal initial bundle).
- **Plugin Lazy-Load:** Plugin UI components lazy-loaded.
- **TanStack Query Caching:** Stale time 60s, Garbage collection 5min, Background refetch on focus.
- **Virtual Scrolling:** Tabellen mit >1000 rows verwenden virtual scrolling (TanStack Virtual).
- **Image Optimization:** User-Avatar via `srcset` + lazy loading.

### Performance Tests

```bash
# Seed 200k contacts
python scripts/seed_perf_data.py --count 200000

# Benchmark list endpoint
curl -w '%{time_total}' 'http://localhost:8000/api/v1/contacts?page=1&page_size=25' -b cookie.txt

# Benchmark FTS search
curl -w '%{time_total}' 'http://localhost:8000/api/v1/contacts?search=Mueller' -b cookie.txt
# Expected: <500ms
```

---

## 9. Test Strategy (F-TEST-01)

> **v1 Core Feature** — F-TEST-01: Testing-Strategie — pytest + httpx (backend), Vitest + Testing Library (frontend), Playwright (E2E).

### Backend (pytest + httpx)

```
tests/
├── conftest.py              — Fixtures: test client, test DB, auth helpers, seed data
├── test_auth.py            — Login, logout, RBAC, password reset, tenant switch
├── test_companies.py       — CRUD, search, filter, pagination, soft-delete, N:M, audit
├── test_contacts.py        — CRUD, search, filter, N:M, DSGVO delete
├── test_tenant.py          — Tenant isolation, cross-tenant access
├── test_plugins.py         — Plugin install/activate/deactivate, event bus, migrations
├── test_dms.py             — Folders, files, upload, search, links, permissions, shares
├── test_calendar.py       — Entries, appointments, tasks, kanban, recurrence, ICS
├── test_mail.py            — Accounts, IMAP mock, send, search, threading, templates
├── test_import_export.py  — CSV import/export, Excel export
├── test_notifications.py   — Create, read, unread count
├── test_health.py          — Health endpoint
├── test_ai_copilot.py     — KI-Copilot API (query, execute, RBAC enforcement, history)
├── test_workflows.py       — Workflow CRUD, instances, steps, approval/rejection, event triggers
├── test_monitoring.py     — Extended health check, Prometheus metrics, alerting
└── test_performance.py    — 200k seed + list <500ms, FTS <500ms, export streaming
```

**Coverage Target:** >80% backend (measured via pytest-cov).

### Frontend (Vitest + Testing Library)

```
frontend/src/__tests__/
├── components/             — UI component tests
├── features/               — Feature integration tests
└── hooks/                  — Custom hook tests
```

### E2E (Playwright)

```
e2e/
├── auth.spec.ts            — Login → logout
├── company-crud.spec.ts    — Create → edit → delete company
├── contact-crud.spec.ts    — Create → link to company → delete
├── search.spec.ts          — Global search
└── plugin-toggle.spec.ts   — Activate/deactivate plugin
```

---

## 10. ADRs (Architecture Decision Records)

### ADR-01: PostgreSQL 16 instead of SQLite

**Context:** Original requirements specified SQLite. System needs 200k records + multi-user concurrent writes.

**Decision:** PostgreSQL 16.

**Rationale:** SQLite has file-level locking (~15 updates/sec under concurrency). PostgreSQL uses MVCC (~1500 updates/sec). Full-Text-Search via `tsvector` + GIN indexes. JSONB support for flexible fields.

**Alternatives:** SQLite+WAL (insufficient concurrency), MySQL (no native FTS in same way), MongoDB (no relational integrity).

### ADR-02: ARQ instead of Celery for Background Jobs

**Context:** Background jobs needed for exports, mail-sync, reminders, backups.

**Decision:** ARQ (async Redis-based job queue for Python).

**Rationale:** Native async (works with FastAPI/asyncio). Simpler than Celery. Redis already in stack for caching. No separate broker needed. Lightweight.

**Alternatives:** Celery (heavier, needs RabbitMQ or Redis as broker), FastAPI BackgroundTasks (no retry, no status tracking, no persistence).

### ADR-03: Plugin System via Python Entry Points + Manifest

**Context:** Module system needed for Mail, Calendar, DMS, Tags as plugins.

**Decision:** Built-in plugins in `app/plugins/builtins/` with manifest-driven registration. No dynamic external plugin loading in v1.

**Rationale:** All v1 plugins are built-in (shipped with the code). External plugin installation is post-MVP. Manifest provides metadata for UI registration and lifecycle hooks. Simpler and safer than dynamic imports.

**Alternatives:** Dynamic pip-installable plugins (complex, security risk for v1), Microservices (overkill for small team).

### ADR-04: TanStack Query for Server State

**Context:** Frontend needs to manage API data with caching, loading states, error handling.

**Decision:** TanStack Query (React Query v5).

**Rationale:** Built-in caching, optimistic updates, background refetching, request deduplication. Eliminates need for global state manager for API data. Works with React 18 Suspense.

**Alternatives:** Redux Toolkit Query (heavier), SWR (less features), manual fetch+useEffect (no caching).

### ADR-05: Session-based Auth instead of JWT

**Context:** Requirements specify session-based auth with HttpOnly cookies.

**Decision:** Server-side sessions in Redis (primary store for fast lookup), session ID in HttpOnly+Secure+SameSite=Strict cookie. PostgreSQL `sessions` table retains session records as an audit trail (created_at, expires_at, user_id, tenant_id).

**Rationale:** No JWT complexity (refresh tokens, rotation). Server can invalidate sessions immediately (delete Redis key). CSRF protection via SameSite=Strict + Origin validation. 8h timeout (Redis TTL). Redis for fast session lookup on every request; PostgreSQL `sessions` table as immutable audit trail for security analysis. Session validation flow: check Redis key → if expired/missing, check PostgreSQL audit record for forensic logging → deny request.

**Alternatives:** JWT (harder to invalidate, token leakage risk), OAuth2 (overkill for internal CRM).

### ADR-06: Soft-Delete with deleted_at Column

**Context:** Companies and contacts need recoverable deletion.

**Decision:** `deleted_at TIMESTAMPTZ NULL` column. NULL = active, NOT NULL = soft-deleted.

**Rationale:** Simple, queryable, recoverable. ORM auto-filters `deleted_at IS NULL` on list endpoints. DSGVO hard-delete removes row entirely and logs to `deletion_log`.

**Alternatives:** Separate trash table (more complex), status column (less clear semantics).

---

## Open Questions

1. **SMTP Provider (Production):** Welcher Provider? → Deployment-Phase.
2. **Backup Strategy:** pg_dump + S3 or Coolify volume backup? → Deployment-Phase.
3. **OnlyOffice:** Separate container or embedded? → Separate container confirmed in docker-compose.
4. **Frontend Calendar Library:** FullCalendar (heavy) or custom React implementation? → Implementation-Phase.

---

## Documentation (F-DOC-01)

> **v1 Core Feature** — F-DOC-01: Dokumentation — README.md, docs/admin-guide.md, docs/api-overview.md, Swagger UI at /api/v1/docs.

## Handoff

- Architecture status: COMPLETE
- Task graph status: PENDING (see task_graph.json)
- AGENTS.md status: PENDING
- Open questions: 4 (listed above, non-blocking for implementation)
- Ready for implementation: NO (pending quality_reviewer review + task graph + AGENTS.md)