feat: role-based permissions (owner/partner/associate/paralegal/secretary)

Backend:
- auth/permissions.go: full permission matrix with RequirePermission/RequireRole
  middleware, CanEditCase, CanDeleteDocument helpers
- auth/context.go: add user role to request context
- auth/middleware.go: resolve role alongside tenant in auth flow
- auth/tenant_resolver.go: verify membership + resolve role for X-Tenant-ID
- handlers/case_assignments.go: CRUD for case-level user assignments
- handlers/tenant_handler.go: UpdateMemberRole, GetMe (/api/me) endpoints
- handlers/documents.go: permission-based delete (own vs all)
- router/router.go: permission-wrapped routes for all endpoints
- services/case_assignment_service.go: assign/unassign with tenant validation
- services/tenant_service.go: UpdateMemberRole with owner protection
- models/case_assignment.go: CaseAssignment model

Database:
- user_tenants.role: CHECK constraint (owner/partner/associate/paralegal/secretary)
- case_assignments table: case_id, user_id, role (lead/team/viewer)
- Migrated existing admin->partner, member->associate

Frontend:
- usePermissions hook: fetches /api/me, provides can() helper
- TeamSettings: 5-role dropdown, role change, permission-gated invite
- CaseAssignments: new component for case-level team management
- Sidebar: conditionally hides AI/Settings based on permissions
- Cases page: hides "Neue Akte" button for non-authorized roles
- Case detail: new "Mitarbeiter" tab for assignment management

AUDIT.md

@@ -0,0 +1,482 @@
+# KanzlAI-mGMT MVP Audit
+
+**Date:** 2026-03-28
+**Auditor:** athena (consultant)
+**Scope:** Full-stack audit of KanzlAI-mGMT — Go backend, Next.js frontend, Supabase database, deployment, security, UX, competitive positioning.
+**Codebase:** ~16,500 lines across ~60 source files, built 2026-03-25 in a single session with parallel workers.
+
+---
+
+## Executive Summary
+
+KanzlAI-mGMT is an impressive MVP built in ~2 hours. It covers the core Kanzleimanagement primitives: cases, deadlines, appointments, parties, documents, notes, dashboard, CalDAV sync, and AI-powered deadline extraction. The architecture is sound — clean separation between Go API and Next.js frontend, proper multi-tenant design with Supabase Auth, parameterized SQL throughout.
+
+However, the speed of construction shows. There are **critical security gaps** that must be fixed before any external user touches this. The frontend has good bones but lacks the polish and completeness a lawyer would expect. And the feature gap vs. established competitors (RA-MICRO, ADVOWARE, AnNoText, Actaport) is enormous — particularly around beA integration, billing/RVG, and document generation, which are table-stakes for German law firms.
+
+**Bottom line:** Fix the security issues, add error recovery and multi-tenant auth verification, then decide whether to pursue the Kanzleimanagement market (massive feature gap) or pivot back to the UPC niche (where you had a genuine competitive advantage).
+
+---
+
+## 1. Critical Issues (Fix Immediately)
+
+### 1.1 Tenant Isolation Bypass in TenantResolver
+**File:** `backend/internal/auth/tenant_resolver.go:37-42`
+
+When the `X-Tenant-ID` header is provided, the TenantResolver parses it and sets it in context **without verifying the user has access to that tenant**. Any authenticated user can access any tenant's data by setting this header.
+
+```go
+if header := r.Header.Get("X-Tenant-ID"); header != "" {
+    parsed, err := uuid.Parse(header)
+    // ... sets tenantID = parsed — NO ACCESS CHECK
+}
+```
+
+Compare with `helpers.go:32-44` where `resolveTenant()` correctly verifies access via `user_tenants` — but this function is unused in the middleware path. The TenantResolver middleware is what actually runs for all scoped routes.
+
+**Impact:** Complete tenant data isolation breach. User A can read/modify/delete User B's cases, deadlines, appointments, documents.
+
+**Fix:** Add `user_tenants` lookup in TenantResolver when X-Tenant-ID is provided, same as `resolveTenant()` does.
+
+### 1.2 Duplicate Tenant Resolution Logic
+**Files:** `backend/internal/auth/tenant_resolver.go` and `backend/internal/handlers/helpers.go:25-57`
+
+Two independent implementations of tenant resolution exist. The middleware (`TenantResolver`) is used for the scoped routes. The handler-level `resolveTenant()` function exists in helpers.go. The auth middleware in `middleware.go:39-47` also resolves a tenant into context. This triple-resolution creates confusion and the security bug above.
+
+**Fix:** Consolidate to a single path. Remove the handler-level `resolveTenant()` and the auth middleware's tenant resolution. Let TenantResolver be the single source of truth, but make it verify access.
+
+### 1.3 CalDAV Credentials Stored in Plaintext
+**File:** `backend/internal/services/caldav_service.go:29-35`
+
+CalDAV username and password are stored as plain JSON in the `tenants.settings` column:
+```go
+type CalDAVConfig struct {
+    URL      string `json:"url"`
+    Username string `json:"username"`
+    Password string `json:"password"`
+    ...
+}
+```
+
+Combined with the tenant isolation bypass above, any authenticated user can read any tenant's CalDAV credentials.
+
+**Fix:** Encrypt CalDAV credentials at rest (e.g., using `pgcrypto` or application-level encryption). At minimum, never return the password in API responses.
+
+### 1.4 No CORS Configuration
+**File:** `backend/internal/router/router.go`, `backend/cmd/server/main.go`
+
+There is zero CORS handling anywhere in the backend. The frontend uses Next.js rewrites to proxy `/api/` to the backend, which works in production. But:
+- If anyone accesses the backend directly (different origin), there's no CORS protection.
+- No `X-Frame-Options`, `X-Content-Type-Options`, or other security headers are set.
+
+**Fix:** Add CORS middleware restricting to the frontend origin. Add standard security headers.
+
+### 1.5 Internal Error Messages Leaked to Clients
+**Files:** Multiple handlers (e.g., `cases.go:44`, `cases.go:73`, `appointments.go`)
+
+```go
+writeError(w, http.StatusInternalServerError, err.Error())
+```
+
+Internal error messages (including SQL errors, connection errors, etc.) are sent directly to the client. This leaks implementation details.
+
+**Fix:** Log the full error server-side, return a generic message to the client.
+
+### 1.6 Race Condition in HolidayService Cache
+**File:** `backend/internal/services/holidays.go`
+
+The `HolidayService` uses a `map[int][]Holiday` cache without any mutex protection. Concurrent requests (e.g., multiple deadline calculations) will cause a data race. The Go race detector would flag this.
+
+**Fix:** Add `sync.RWMutex` to HolidayService.
+
+### 1.7 Rate Limiter Trivially Bypassable
+**File:** `backend/internal/middleware/ratelimit.go:78-79`
+
+```go
+ip := r.Header.Get("X-Forwarded-For")
+if ip == "" { ip = r.RemoteAddr }
+```
+
+Rate limiting keys off `X-Forwarded-For`, which any client can spoof. An attacker can bypass AI endpoint rate limits by rotating this header.
+
+**Fix:** Only trust `X-Forwarded-For` from configured reverse proxy IPs, or use `r.RemoteAddr` exclusively behind a trusted proxy.
+
+---
+
+## 2. Important Gaps (Fix Before Showing to Anyone)
+
+### 2.1 No Input Validation Beyond "Required Fields"
+**Files:** All handlers
+
+Input validation is minimal — typically just checking if required fields are empty:
+```go
+if input.CaseNumber == "" || input.Title == "" {
+    writeError(w, http.StatusBadRequest, "case_number and title are required")
+}
+```
+
+Missing:
+- Length limits on text fields (could store megabytes in a title field)
+- Status value validation (accepts any string for status fields)
+- Date format validation
+- Case type validation against allowed values
+- SQL-safe string validation (although parameterized queries protect against injection)
+
+### 2.2 No Pagination Defaults on Most List Endpoints
+**File:** `backend/internal/services/case_service.go:57-63`
+
+`CaseService.List` has sane defaults (limit=20, max=100). But other list endpoints (`appointments`, `deadlines`, `notes`, `parties`, `case_events`) have no pagination at all — they return all records for a tenant/case. As data grows, these become performance problems.
+
+### 2.3 Dashboard Page is Entirely Client-Side
+**File:** `frontend/src/app/(app)/dashboard/page.tsx`
+
+The entire dashboard is a `"use client"` component that fetches data via API. This means:
+- No SSR benefit — the page is blank until JS loads and API responds
+- SEO doesn't matter for a SaaS app, but initial load time does
+- The skeleton is nice but adds 200-400ms of perceived latency
+
+For an internal tool this is acceptable, but for a commercial product it should use server components for the initial render.
+
+### 2.4 Frontend Auth Uses `getSession()` Instead of `getUser()`
+**File:** `frontend/src/lib/api.ts:10-12`
+
+```typescript
+const { data: { session } } = await supabase.auth.getSession();
+```
+
+`getSession()` reads from local storage without server verification. If a session is expired or revoked server-side, the frontend will still try to use it until the backend rejects it. The middleware correctly uses `getUser()` (which validates server-side), but the API client does not.
+
+### 2.5 Missing Error Recovery in Frontend
+Throughout the frontend, API errors are handled with basic error states, but there's no:
+- Retry logic for transient failures
+- Token refresh on 401 responses
+- Optimistic UI rollback on mutation failures
+- Offline detection
+
+### 2.6 Missing `Content-Disposition` Header Sanitization
+**File:** `backend/internal/handlers/documents.go:133`
+
+```go
+w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="%s"`, title))
+```
+
+The `title` (which comes from user input) is inserted directly into the header. A filename containing `"` or newlines could be used for response header injection.
+
+**Fix:** Sanitize the filename — strip or encode special characters.
+
+### 2.7 No Graceful Shutdown
+**File:** `backend/cmd/server/main.go:42`
+
+```go
+http.ListenAndServe(":"+cfg.Port, handler)
+```
+
+No signal handling or graceful shutdown. When the process receives SIGTERM (e.g., during deployment), in-flight requests are dropped, CalDAV sync operations may be interrupted mid-write, and database connections are not cleanly closed.
+
+### 2.8 Database Connection Pool — search_path is Session-Level
+**File:** `backend/internal/db/connection.go:17`
+
+```go
+db.Exec("SET search_path TO kanzlai, public")
+```
+
+`SET search_path` is session-level in PostgreSQL. With connection pooling (`MaxOpenConns: 25`), this SET runs once on the initial connection. If a connection is recycled or a new one opened from the pool, it may not have the kanzlai search_path. This could cause queries to silently hit the wrong schema.
+
+**Fix:** Use `SET LOCAL search_path` in a transaction, or set it at the database/role level, or qualify all table references with the schema name.
+
+### 2.9 go.sum Missing from Dockerfile
+**File:** `backend/Dockerfile:4`
+
+```dockerfile
+COPY go.mod ./
+RUN go mod download
+```
+
+Only `go.mod` is copied, not `go.sum`. This means the build isn't reproducible and doesn't verify checksums. Should be `COPY go.mod go.sum ./`.
+
+### 2.10 German Umlaut Typos Throughout Frontend
+**Files:** Multiple frontend components
+
+German strings use ASCII approximations instead of proper characters:
+- `login/page.tsx`: "Zurueck" instead of "Zurück"
+- `cases/[id]/layout.tsx`: "Anhaengig" instead of "Anhängig"
+- `cases/[id]/fristen/page.tsx`: "Ueberfaellig" instead of "Überfällig"
+- `termine/page.tsx`: "Uberblick" instead of "Überblick"
+
+A German lawyer would notice this immediately. It signals "this was built by a machine, not tested by a human."
+
+### 2.11 Silent Error Swallowing in Event Creation
+**File:** `backend/internal/services/case_service.go:260-266`
+
+```go
+func createEvent(ctx context.Context, db *sqlx.DB, ...) {
+    db.ExecContext(ctx, /* ... */)  // Error completely ignored
+}
+```
+
+Case events (audit trail) silently fail to create. The calling functions don't check the return. This means you could have cases with no events and no way to know why.
+
+### 2.12 Missing Error Boundaries in Frontend
+No React error boundaries are implemented. If any component throws, the entire page crashes with a white screen. For a law firm tool where data integrity matters, this is unacceptable.
+
+### 2.13 No RLS Policies Defined at Database Level
+Multi-tenant isolation relies entirely on `WHERE tenant_id = $X` clauses in Go code. If any query forgets this clause, data leaks across tenants. There are no PostgreSQL RLS policies as a safety net.
+
+**Fix:** Enable RLS on all tenant-scoped tables and create policies tied to `auth.uid()` via `user_tenants`.
+
+---
+
+## 3. Architecture Assessment
+
+### 3.1 What's Good
+
+- **Clean monorepo structure** — `backend/` and `frontend/` are clearly separated. Each has its own Dockerfile. The Makefile provides unified commands.
+- **Go backend is well-organized** — `cmd/server/`, `internal/{auth,config,db,handlers,middleware,models,router,services}` follows Go best practices.
+- **Handler/Service separation** — handlers do HTTP concerns (parse request, write response), services do business logic. This is correct.
+- **Parameterized SQL everywhere** — no string concatenation in queries. All user input goes through `$N` placeholders.
+- **Multi-tenant design** — `tenant_id` on every row, context-based tenant resolution, RLS at the database level.
+- **Smart use of Go 1.22+ routing** — method+path patterns like `GET /api/cases/{id}` eliminate the need for a third-party router.
+- **CalDAV sync is genuinely impressive** — bidirectional sync with conflict resolution, etag tracking, background polling per-tenant. This is a differentiator.
+- **Deadline calculator** — ported from youpc.org with holiday awareness. Legally important and hard to build.
+- **Frontend routing structure** — German URL paths (`/fristen`, `/termine`, `/einstellungen`), nested case detail routes with layout.tsx for shared chrome. Proper use of App Router patterns.
+
+### 3.2 Structural Concerns
+
+- **No database migrations** — the schema was apparently created via SQL scripts run manually. There's a `seed/demo_data.sql` but no migration system. For a production system, this is unsustainable.
+- **No CI/CD pipeline** — no `.github/workflows/`, `.gitea/`, or any CI configuration. Tests run locally but not automatically.
+- **No API versioning** — all routes are at `/api/`. Adding breaking changes will break clients.
+- **Services take raw `*sqlx.DB`** — no transaction support across service boundaries. Creating a case + event is not atomic (if the event insert fails, the case still exists).
+- **Models are just struct definitions** — no validation methods, no constructor functions. Validation is scattered across handlers.
+
+### 3.3 Data Model
+
+Based on the seed data and model files, the schema is reasonable:
+- `tenants`, `user_tenants` (multi-tenancy)
+- `cases`, `parties` (case management)
+- `deadlines`, `appointments` (time management)
+- `documents`, `case_events`, `notes` (supporting data)
+- `proceeding_types`, `deadline_rules`, `holidays` (reference data)
+
+**Missing indexes likely needed:**
+- `deadlines(tenant_id, status, due_date)` — for dashboard queries
+- `appointments(tenant_id, start_at)` — for calendar queries
+- `case_events(case_id, created_at)` — for event feeds
+- `cases(tenant_id, status)` — for filtered lists
+
+**Missing constraints:**
+- No CHECK constraint on status values (cases, deadlines, appointments)
+- No UNIQUE constraint on `case_number` per tenant
+- No foreign key from `notes` to the parent entity (if polymorphic)
+
+---
+
+## 4. Security Assessment
+
+### 4.1 Authentication
+- **JWT validation is correct** — algorithm check (HMAC only), expiry check, sub claim extraction. Using `golang-jwt/v5`.
+- **Supabase Auth on frontend** — proper cookie-based session with server-side verification in middleware.
+- **No refresh token rotation** — the API client uses `getSession()` which may serve stale tokens.
+
+### 4.2 Authorization
+- **Critical: Tenant isolation bypass** (see 1.1)
+- **No role-based access control** — `user_tenants` has a `role` column but it's never checked. Any member can do anything.
+- **No resource-level permissions** — any user in a tenant can delete any case, document, etc.
+
+### 4.3 Input Validation
+- **SQL injection: Protected** — all queries use parameterized placeholders.
+- **XSS: Partially protected** — React auto-escapes, but the API returns raw strings that could contain HTML. The `Content-Disposition` header is vulnerable (see 2.6).
+- **File upload: Partially protected** — `MaxBytesReader` limits to 50MB, but no file type validation (could upload .exe, .html with scripts, etc.).
+- **Rate limiting: AI endpoints only** — the rest of the API has no rate limiting. Login/register go through Supabase (which has its own limits), but all CRUD endpoints are unlimited.
+
+### 4.4 Secrets
+- **No hardcoded secrets** — all via environment variables. Good.
+- **CalDAV credentials in plaintext** — see 1.3.
+- **Supabase service key in backend** — necessary for storage, but this key has full DB access. Should be scoped.
+
+---
+
+## 5. Testing Assessment
+
+### 5.1 Backend Tests (15 files)
+- **Integration test** — sets up real DB connection, creates JWT, tests full HTTP flow. Excellent pattern but requires DATABASE_URL (skips otherwise).
+- **Handler tests** — mock-based unit tests for most handlers. Test JSON parsing, error responses, basic happy paths.
+- **Service tests** — deadline calculator has solid date arithmetic tests. Holiday service tested. CalDAV service tested with mocks. AI service tested with mocked HTTP.
+- **Middleware tests** — rate limiter tested.
+- **Auth tests** — tenant resolver tested.
+
+### 5.2 Frontend Tests (4 files)
+- `api.test.ts` — tests the API client
+- `DeadlineTrafficLights.test.tsx` — component test
+- `CaseOverviewGrid.test.tsx` — component test
+- `LoginPage.test.tsx` — auth page test
+
+### 5.3 What's Missing
+- **No E2E tests** — no Playwright/Cypress. Critical for a law firm app where correctness matters.
+- **No contract tests** — frontend and backend are tested independently. A schema change could break the frontend without any test catching it.
+- **Deadline calculation edge cases** — needs tests for year boundaries, leap years, holidays falling on weekends, multiple consecutive holidays.
+- **Multi-tenant security tests** — no test verifying that User A can't access Tenant B's data. This is the most important test to add.
+- **Frontend test coverage is thin** — 4 tests for ~30 components. The dashboard, all forms, navigation, error states are untested.
+- **No load testing** — unknown how the system behaves under concurrent users.
+
+---
+
+## 6. UX Assessment
+
+### 6.1 What Works
+- **Dashboard is strong** — traffic light deadline indicators, upcoming timeline, case overview, quick actions. A lawyer can see what matters at a glance.
+- **German localization** — UI is in German with proper legal terminology (Akten, Fristen, Termine, Parteien).
+- **Mobile responsive** — sidebar collapses to hamburger menu, layout uses responsive grids.
+- **Loading states** — skeleton screens on dashboard, not just spinners.
+- **Breadcrumbs** — navigation trail on all pages.
+- **Deadline calculator** — unique feature that provides real value for UPC litigation.
+
+### 6.2 What a Lawyer Would Stumble On
+1. **No onboarding flow** — after registration, user has no tenant, no cases. The app shows empty states but doesn't guide the user to create a tenant or import data.
+2. **No search** — there's no global search. A lawyer with 100+ cases needs to find things fast.
+3. **No keyboard shortcuts** — power users (lawyers are keyboard-heavy) have no shortcuts.
+4. **Sidebar mixes languages** — "Akten" (German) vs "AI Analyse" (English). Should be consistent.
+5. **No notifications** — overdue deadlines don't trigger any alert beyond the dashboard color. No email alerts, no push notifications.
+6. **No print view** — lawyers need to print deadline lists, case summaries. No print stylesheet.
+7. **No bulk operations** — can't mark multiple deadlines as complete, can't bulk-assign parties.
+8. **Document upload has no preview** — uploaded PDFs can't be viewed inline.
+9. **AI features require manual trigger** — AI summary and deadline extraction are manual. Should auto-trigger on document upload.
+10. **No activity log per user** — no audit trail of who changed what. Critical for law firm compliance.
+
+---
+
+## 7. Deployment Assessment
+
+### 7.1 Docker Setup
+- **Multi-stage builds** — both Dockerfiles use builder pattern. Good.
+- **Backend is minimal** — Alpine + static binary + ca-certificates. ~15MB image.
+- **Frontend** — Bun for deps/build, Node for runtime (standalone output). Reasonable.
+- **Missing:** go.sum not copied in backend Dockerfile (see 2.9).
+- **Missing:** No docker-compose.yml for local development.
+- **Missing:** No health check in Dockerfile (`HEALTHCHECK` instruction).
+
+### 7.2 Environment Handling
+- **Config validates required vars** — `DATABASE_URL` and `SUPABASE_JWT_SECRET` are checked at startup.
+- **Supabase URL/keys not validated** — if missing, features silently fail or crash at runtime.
+- **No .env.example** — new developers don't know what env vars are needed.
+
+### 7.3 Reliability
+- **No graceful shutdown** (see 2.7)
+- **No readiness/liveness probes** — `/health` exists but only checks DB connectivity. No readiness distinction.
+- **CalDAV sync runs in-process** — if the sync goroutine panics, it takes down the API server.
+- **No structured error recovery** — panics in handlers will crash the process (no recovery middleware).
+
+---
+
+## 8. Competitive Analysis
+
+### 8.1 The Market
+
+German Kanzleisoftware is a mature, crowded market:
+
+| Tool | Type | Price | Key Strength |
+|------|------|-------|-------------|
+| **RA-MICRO** | Desktop + Cloud | ~100-200 EUR/user/mo | Market leader, 30+ years, full beA integration |
+| **ADVOWARE** | Desktop + Cloud | from 20 EUR/mo | Budget-friendly, strong for small firms |
+| **AnNoText** (Wolters Kluwer) | Desktop + Cloud | Custom pricing | Enterprise, AI document analysis, DictNow |
+| **Actaport** | Cloud-native | from 79.80 EUR/mo | Modern UI, Mandantenportal, integrated Office |
+| **Haufe Advolux** | Cloud | Custom | User-friendly, full-featured |
+| **Renostar Legal Cloud** | Cloud | Custom | Browser-based, no installation |
+
+### 8.2 Table-Stakes Features KanzlAI is Missing
+
+These are **mandatory** for any German Kanzleisoftware to be taken seriously:
+
+1. **beA Integration** — since 2022, German lawyers must use the electronic court mailbox (besonderes elektronisches Anwaltspostfach). No Kanzleisoftware sells without it. This is a **massive** implementation effort (KSW-Schnittstelle from BRAK).
+
+2. **RVG Billing (Gebührenrechner)** — automated fee calculation per RVG (Rechtsanwaltsvergütungsgesetz). Every competitor has this built-in. Without it, lawyers can't bill clients.
+
+3. **Document Generation** — templates for Schriftsätze, Klageschriften, Mahnbescheide with auto-populated case data. Usually integrated with Word.
+
+4. **Accounting (FiBu)** — client trust accounts (Fremdgeld), DATEV export, tax-relevant bookkeeping. Legal requirement.
+
+5. **Conflict Check (Kollisionsprüfung)** — check if the firm has a conflict of interest before taking a case. Legally required (§ 43a BRAO).
+
+6. **Dictation System** — voice-to-text for lawyers. RA-MICRO has DictaNet, AnNoText has DictNow.
+
+### 8.3 Where KanzlAI Could Differentiate
+
+Despite the feature gap, KanzlAI has some advantages:
+
+1. **AI-native** — competitors are bolting AI onto 20-year-old software. KanzlAI has Claude API integration from day one. The deadline extraction from PDFs is genuinely useful.
+2. **UPC specialization** — the deadline calculator with UPC Rules of Procedure knowledge is unique. No competitor has deep UPC litigation support.
+3. **CalDAV sync** — bidirectional sync with external calendars is not common in German Kanzleisoftware.
+4. **Modern tech stack** — React + Go + Supabase vs. the .NET/Java/Desktop world of RA-MICRO et al.
+5. **Multi-tenant from day 1** — designed for SaaS, not converted from desktop software.
+
+### 8.4 Strategic Recommendation
+
+**Don't compete head-on with RA-MICRO.** The feature gap is 10+ person-years of work. Instead:
+
+**Option A: UPC Niche Tool** — Pivot back to UPC patent litigation. Build the best deadline calculator, case tracker, and AI-powered brief analysis tool for UPC practitioners. There are ~1000 UPC practitioners in Europe who need specialized tooling that RA-MICRO doesn't provide. Charge 200-500 EUR/mo.
+
+**Option B: AI-First Legal Assistant** — Don't call it "Kanzleimanagement." Position as an AI assistant that reads court documents, extracts deadlines, and syncs to the lawyer's existing Kanzleisoftware via CalDAV/iCal. This sidesteps the feature gap entirely.
+
+**Option C: Full Kanzleisoftware** — If you pursue this, beA integration is the first priority, then RVG billing. Without these two, no German lawyer will switch.
+
+---
+
+## 9. Strengths (What's Good, Keep Doing It)
+
+1. **Architecture is solid** — the Go + Next.js + Supabase stack is well-chosen. Clean separation of concerns.
+2. **SQL is safe** — parameterized queries throughout. No injection vectors.
+3. **Multi-tenant design** — tenant_id scoping with RLS is the right approach.
+4. **CalDAV implementation** — genuinely impressive for an MVP. Bidirectional sync with conflict resolution.
+5. **Deadline calculator** — ported from youpc.org with holiday awareness. Real domain value.
+6. **AI integration** — Claude API with tool use for structured extraction. Clean implementation.
+7. **Dashboard UX** — traffic lights, timeline, quick actions. Lawyers will get this immediately.
+8. **German-first** — proper legal terminology, German date formats, localized UI.
+9. **Test foundation** — 15 backend test files with integration tests. Good starting point.
+10. **Docker builds are lean** — multi-stage, Alpine-based, standalone Next.js output.
+
+---
+
+## 10. Priority Roadmap
+
+### P0 — This Week
+- [ ] Fix tenant isolation bypass in TenantResolver (1.1)
+- [ ] Consolidate tenant resolution logic (1.2)
+- [ ] Encrypt CalDAV credentials at rest (1.3)
+- [ ] Add CORS middleware + security headers (1.4)
+- [ ] Stop leaking internal errors to clients (1.5)
+- [ ] Add mutex to HolidayService cache (1.6)
+- [ ] Fix rate limiter X-Forwarded-For bypass (1.7)
+- [ ] Fix Dockerfile go.sum copy (2.9)
+
+### P1 — Before Demo/Beta
+- [ ] Add input validation (length limits, allowed values) (2.1)
+- [ ] Add pagination to all list endpoints (2.2)
+- [ ] Fix `search_path` connection pool issue (2.8)
+- [ ] Add graceful shutdown with signal handling (2.7)
+- [ ] Sanitize Content-Disposition filename (2.6)
+- [ ] Fix German umlaut typos throughout frontend (2.10)
+- [ ] Handle createEvent errors instead of swallowing (2.11)
+- [ ] Add React error boundaries (2.12)
+- [ ] Implement RLS policies on all tenant-scoped tables (2.13)
+- [ ] Add multi-tenant security tests
+- [ ] Add database migrations system
+- [ ] Add `.env.example` file
+- [ ] Add onboarding flow for new users
+
+### P2 — Next Iteration
+- [ ] Role-based access control (admin/member/readonly)
+- [ ] Global search
+- [ ] Email notifications for overdue deadlines
+- [ ] Audit trail / activity log per user
+- [ ] Auto-trigger AI extraction on document upload
+- [ ] Print-friendly views
+- [ ] E2E tests with Playwright
+- [ ] CI/CD pipeline
+
+### P3 — Strategic
+- [ ] Decide market positioning (UPC niche vs. AI assistant vs. full Kanzleisoftware)
+- [ ] If Kanzleisoftware: begin beA integration research
+- [ ] If Kanzleisoftware: RVG Gebührenrechner
+- [ ] If UPC niche: integrate lex-research case law database
+
+---
+
+*This audit was conducted by reading every source file in the repository, running all tests, analyzing the database schema via seed data, and comparing against established German Kanzleisoftware competitors.*

backend/internal/auth/context.go

@@ -11,6 +11,7 @@ type contextKey string
 const (
 	userIDKey   contextKey = "user_id"
 	tenantIDKey contextKey = "tenant_id"
+	userRoleKey contextKey = "user_role"
 )
 
 func ContextWithUserID(ctx context.Context, userID uuid.UUID) context.Context {
@@ -30,3 +31,12 @@ func TenantFromContext(ctx context.Context) (uuid.UUID, bool) {
 	id, ok := ctx.Value(tenantIDKey).(uuid.UUID)
 	return id, ok
 }
+
+func ContextWithUserRole(ctx context.Context, role string) context.Context {
+	return context.WithValue(ctx, userRoleKey, role)
+}
+
+func UserRoleFromContext(ctx context.Context) string {
+	role, _ := ctx.Value(userRoleKey).(string)
+	return role
+}

backend/internal/auth/middleware.go

@@ -36,15 +36,19 @@ func (m *Middleware) RequireAuth(next http.Handler) http.Handler {
 
 		ctx := ContextWithUserID(r.Context(), userID)
 
-		// Resolve tenant from user_tenants
-		var tenantID uuid.UUID
-		err = m.db.GetContext(r.Context(), &tenantID,
-			"SELECT tenant_id FROM user_tenants WHERE user_id = $1 LIMIT 1", userID)
+		// Resolve tenant and role from user_tenants
+		var membership struct {
+			TenantID uuid.UUID `db:"tenant_id"`
+			Role     string    `db:"role"`
+		}
+		err = m.db.GetContext(r.Context(), &membership,
+			"SELECT tenant_id, role FROM user_tenants WHERE user_id = $1 LIMIT 1", userID)
 		if err != nil {
 			http.Error(w, "no tenant found for user", http.StatusForbidden)
 			return
 		}
-		ctx = ContextWithTenantID(ctx, tenantID)
+		ctx = ContextWithTenantID(ctx, membership.TenantID)
+		ctx = ContextWithUserRole(ctx, membership.Role)
 
 		next.ServeHTTP(w, r.WithContext(ctx))
 	})

backend/internal/auth/permissions.go

@@ -0,0 +1,213 @@
+package auth
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/google/uuid"
+	"github.com/jmoiron/sqlx"
+)
+
+// Valid roles ordered by privilege level (highest first).
+var ValidRoles = []string{"owner", "partner", "associate", "paralegal", "secretary"}
+
+// IsValidRole checks if a role string is one of the defined roles.
+func IsValidRole(role string) bool {
+	for _, r := range ValidRoles {
+		if r == role {
+			return true
+		}
+	}
+	return false
+}
+
+// Permission represents an action that can be checked against roles.
+type Permission int
+
+const (
+	PermManageTeam Permission = iota
+	PermManageBilling
+	PermCreateCase
+	PermEditAllCases
+	PermEditAssignedCase
+	PermViewAllCases
+	PermManageDeadlines
+	PermManageAppointments
+	PermUploadDocuments
+	PermDeleteDocuments
+	PermDeleteOwnDocuments
+	PermViewAuditLog
+	PermManageSettings
+	PermAIExtraction
+)
+
+// rolePermissions maps each role to its set of permissions.
+var rolePermissions = map[string]map[Permission]bool{
+	"owner": {
+		PermManageTeam:         true,
+		PermManageBilling:      true,
+		PermCreateCase:         true,
+		PermEditAllCases:       true,
+		PermEditAssignedCase:   true,
+		PermViewAllCases:       true,
+		PermManageDeadlines:    true,
+		PermManageAppointments: true,
+		PermUploadDocuments:    true,
+		PermDeleteDocuments:    true,
+		PermDeleteOwnDocuments: true,
+		PermViewAuditLog:       true,
+		PermManageSettings:     true,
+		PermAIExtraction:       true,
+	},
+	"partner": {
+		PermManageTeam:         true,
+		PermManageBilling:      true,
+		PermCreateCase:         true,
+		PermEditAllCases:       true,
+		PermEditAssignedCase:   true,
+		PermViewAllCases:       true,
+		PermManageDeadlines:    true,
+		PermManageAppointments: true,
+		PermUploadDocuments:    true,
+		PermDeleteDocuments:    true,
+		PermDeleteOwnDocuments: true,
+		PermViewAuditLog:       true,
+		PermManageSettings:     true,
+		PermAIExtraction:       true,
+	},
+	"associate": {
+		PermCreateCase:         true,
+		PermEditAssignedCase:   true,
+		PermViewAllCases:       true,
+		PermManageDeadlines:    true,
+		PermManageAppointments: true,
+		PermUploadDocuments:    true,
+		PermDeleteOwnDocuments: true,
+		PermAIExtraction:       true,
+	},
+	"paralegal": {
+		PermEditAssignedCase:   true,
+		PermViewAllCases:       true,
+		PermManageDeadlines:    true,
+		PermManageAppointments: true,
+		PermUploadDocuments:    true,
+	},
+	"secretary": {
+		PermViewAllCases:       true,
+		PermManageAppointments: true,
+		PermUploadDocuments:    true,
+	},
+}
+
+// HasPermission checks if the given role has the specified permission.
+func HasPermission(role string, perm Permission) bool {
+	perms, ok := rolePermissions[role]
+	if !ok {
+		return false
+	}
+	return perms[perm]
+}
+
+// RequirePermission returns middleware that checks if the user's role has the given permission.
+func RequirePermission(perm Permission) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			role := UserRoleFromContext(r.Context())
+			if role == "" || !HasPermission(role, perm) {
+				writeJSONError(w, "insufficient permissions", http.StatusForbidden)
+				return
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+// RequireRole returns middleware that checks if the user has one of the specified roles.
+func RequireRole(roles ...string) func(http.Handler) http.Handler {
+	allowed := make(map[string]bool, len(roles))
+	for _, r := range roles {
+		allowed[r] = true
+	}
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			role := UserRoleFromContext(r.Context())
+			if !allowed[role] {
+				writeJSONError(w, "insufficient permissions", http.StatusForbidden)
+				return
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+// IsAssignedToCase checks if a user is assigned to a specific case.
+func IsAssignedToCase(ctx context.Context, db *sqlx.DB, userID, caseID uuid.UUID) (bool, error) {
+	var exists bool
+	err := db.GetContext(ctx, &exists,
+		`SELECT EXISTS(SELECT 1 FROM case_assignments WHERE user_id = $1 AND case_id = $2)`,
+		userID, caseID)
+	return exists, err
+}
+
+// CanEditCase checks if a user can edit a specific case based on role and assignment.
+func CanEditCase(ctx context.Context, db *sqlx.DB, userID, caseID uuid.UUID, role string) (bool, error) {
+	// Owner and partner can edit all cases
+	if HasPermission(role, PermEditAllCases) {
+		return true, nil
+	}
+	// Others need to be assigned
+	if !HasPermission(role, PermEditAssignedCase) {
+		return false, nil
+	}
+	return IsAssignedToCase(ctx, db, userID, caseID)
+}
+
+// CanDeleteDocument checks if a user can delete a specific document.
+func CanDeleteDocument(role string, docUploaderID, userID uuid.UUID) bool {
+	if HasPermission(role, PermDeleteDocuments) {
+		return true
+	}
+	if HasPermission(role, PermDeleteOwnDocuments) {
+		return docUploaderID == userID
+	}
+	return false
+}
+
+// permissionNames maps Permission constants to their string names for frontend use.
+var permissionNames = map[Permission]string{
+	PermManageTeam:         "manage_team",
+	PermManageBilling:      "manage_billing",
+	PermCreateCase:         "create_case",
+	PermEditAllCases:       "edit_all_cases",
+	PermEditAssignedCase:   "edit_assigned_case",
+	PermViewAllCases:       "view_all_cases",
+	PermManageDeadlines:    "manage_deadlines",
+	PermManageAppointments: "manage_appointments",
+	PermUploadDocuments:    "upload_documents",
+	PermDeleteDocuments:    "delete_documents",
+	PermDeleteOwnDocuments: "delete_own_documents",
+	PermViewAuditLog:       "view_audit_log",
+	PermManageSettings:     "manage_settings",
+	PermAIExtraction:       "ai_extraction",
+}
+
+// GetRolePermissions returns a list of permission name strings for the given role.
+func GetRolePermissions(role string) []string {
+	perms, ok := rolePermissions[role]
+	if !ok {
+		return nil
+	}
+	var names []string
+	for p := range perms {
+		if name, ok := permissionNames[p]; ok {
+			names = append(names, name)
+		}
+	}
+	return names
+}
+
+func writeJSONError(w http.ResponseWriter, msg string, status int) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	w.Write([]byte(`{"error":"` + msg + `"}`))
+}

backend/internal/auth/tenant_resolver.go

@@ -12,6 +12,7 @@ import (
 // Defined as an interface to avoid circular dependency with services.
 type TenantLookup interface {
 	FirstTenantForUser(ctx context.Context, userID uuid.UUID) (*uuid.UUID, error)
+	GetUserRole(ctx context.Context, userID, tenantID uuid.UUID) (string, error)
 }
 
 // TenantResolver is middleware that resolves the tenant from X-Tenant-ID header
@@ -40,9 +41,21 @@ func (tr *TenantResolver) Resolve(next http.Handler) http.Handler {
 				http.Error(w, fmt.Sprintf("invalid X-Tenant-ID: %v", err), http.StatusBadRequest)
 				return
 			}
+			// Verify user has access and get their role
+			role, err := tr.lookup.GetUserRole(r.Context(), userID, parsed)
+			if err != nil {
+				http.Error(w, "error checking tenant access", http.StatusInternalServerError)
+				return
+			}
+			if role == "" {
+				http.Error(w, "no access to this tenant", http.StatusForbidden)
+				return
+			}
 			tenantID = parsed
+			// Override the role from middleware with the correct one for this tenant
+			r = r.WithContext(ContextWithUserRole(r.Context(), role))
 		} else {
-			// Default to user's first tenant
+			// Default to user's first tenant (role already set by middleware)
 			first, err := tr.lookup.FirstTenantForUser(r.Context(), userID)
 			if err != nil {
 				http.Error(w, fmt.Sprintf("resolving tenant: %v", err), http.StatusInternalServerError)

backend/internal/auth/tenant_resolver_test.go

@@ -11,6 +11,7 @@ import (
 
 type mockTenantLookup struct {
 	tenantID *uuid.UUID
+	role     string
 	err      error
 }
 
@@ -18,9 +19,16 @@ func (m *mockTenantLookup) FirstTenantForUser(ctx context.Context, userID uuid.U
 	return m.tenantID, m.err
 }
 
+func (m *mockTenantLookup) GetUserRole(ctx context.Context, userID, tenantID uuid.UUID) (string, error) {
+	if m.role != "" {
+		return m.role, m.err
+	}
+	return "associate", m.err
+}
+
 func TestTenantResolver_FromHeader(t *testing.T) {
 	tenantID := uuid.New()
-	tr := NewTenantResolver(&mockTenantLookup{})
+	tr := NewTenantResolver(&mockTenantLookup{role: "partner"})
 
 	var gotTenantID uuid.UUID
 	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

backend/internal/handlers/case_assignments.go

@@ -0,0 +1,119 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/google/uuid"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
+)
+
+type CaseAssignmentHandler struct {
+	svc *services.CaseAssignmentService
+}
+
+func NewCaseAssignmentHandler(svc *services.CaseAssignmentService) *CaseAssignmentHandler {
+	return &CaseAssignmentHandler{svc: svc}
+}
+
+// List handles GET /api/cases/{id}/assignments
+func (h *CaseAssignmentHandler) List(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	caseID, err := uuid.Parse(r.PathValue("id"))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid case ID")
+		return
+	}
+
+	assignments, err := h.svc.ListByCase(r.Context(), tenantID, caseID)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"assignments": assignments,
+		"total":       len(assignments),
+	})
+}
+
+// Assign handles POST /api/cases/{id}/assignments
+func (h *CaseAssignmentHandler) Assign(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	caseID, err := uuid.Parse(r.PathValue("id"))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid case ID")
+		return
+	}
+
+	var req struct {
+		UserID string `json:"user_id"`
+		Role   string `json:"role"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+
+	userID, err := uuid.Parse(req.UserID)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid user_id")
+		return
+	}
+
+	if req.Role == "" {
+		req.Role = "team"
+	}
+	if req.Role != "lead" && req.Role != "team" && req.Role != "viewer" {
+		writeError(w, http.StatusBadRequest, "role must be lead, team, or viewer")
+		return
+	}
+
+	assignment, err := h.svc.Assign(r.Context(), tenantID, caseID, userID, req.Role)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusCreated, assignment)
+}
+
+// Unassign handles DELETE /api/cases/{id}/assignments/{uid}
+func (h *CaseAssignmentHandler) Unassign(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	caseID, err := uuid.Parse(r.PathValue("id"))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid case ID")
+		return
+	}
+
+	userID, err := uuid.Parse(r.PathValue("uid"))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid user ID")
+		return
+	}
+
+	if err := h.svc.Unassign(r.Context(), tenantID, caseID, userID); err != nil {
+		writeError(w, http.StatusNotFound, err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]string{"status": "removed"})
+}

backend/internal/handlers/documents.go

@@ -167,6 +167,7 @@ func (h *DocumentHandler) Delete(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	userID, _ := auth.UserFromContext(r.Context())
+	role := auth.UserRoleFromContext(r.Context())
 
 	docID, err := uuid.Parse(r.PathValue("docId"))
 	if err != nil {
@@ -174,6 +175,26 @@ func (h *DocumentHandler) Delete(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Check permission: owner/partner can delete any, associate can delete own
+	doc, err := h.svc.GetByID(r.Context(), tenantID, docID)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	if doc == nil {
+		writeError(w, http.StatusNotFound, "document not found")
+		return
+	}
+
+	uploaderID := uuid.Nil
+	if doc.UploadedBy != nil {
+		uploaderID = *doc.UploadedBy
+	}
+	if !auth.CanDeleteDocument(role, uploaderID, userID) {
+		writeError(w, http.StatusForbidden, "insufficient permissions to delete this document")
+		return
+	}
+
 	if err := h.svc.Delete(r.Context(), tenantID, docID, userID); err != nil {
 		writeError(w, http.StatusNotFound, "document not found")
 		return

backend/internal/handlers/tenant_handler.go

@@ -117,14 +117,14 @@ func (h *TenantHandler) InviteUser(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Only owners and admins can invite
+	// Only owners and partners can invite
 	role, err := h.svc.GetUserRole(r.Context(), userID, tenantID)
 	if err != nil {
 		jsonError(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-	if role != "owner" && role != "admin" {
-		jsonError(w, "only owners and admins can invite users", http.StatusForbidden)
+	if role != "owner" && role != "partner" {
+		jsonError(w, "only owners and partners can invite users", http.StatusForbidden)
 		return
 	}
 
@@ -141,10 +141,15 @@ func (h *TenantHandler) InviteUser(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	if req.Role == "" {
-		req.Role = "member"
+		req.Role = "associate"
 	}
-	if req.Role != "member" && req.Role != "admin" {
-		jsonError(w, "role must be member or admin", http.StatusBadRequest)
+	if !auth.IsValidRole(req.Role) {
+		jsonError(w, "invalid role", http.StatusBadRequest)
+		return
+	}
+	// Non-owners cannot invite as owner
+	if role != "owner" && req.Role == "owner" {
+		jsonError(w, "only owners can invite as owner", http.StatusForbidden)
 		return
 	}
 
@@ -177,13 +182,13 @@ func (h *TenantHandler) RemoveMember(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Only owners and admins can remove members (or user removing themselves)
+	// Only owners and partners can remove members (or user removing themselves)
 	role, err := h.svc.GetUserRole(r.Context(), userID, tenantID)
 	if err != nil {
 		jsonError(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-	if role != "owner" && role != "admin" && userID != memberID {
+	if role != "owner" && role != "partner" && userID != memberID {
 		jsonError(w, "insufficient permissions", http.StatusForbidden)
 		return
 	}
@@ -210,14 +215,14 @@ func (h *TenantHandler) UpdateSettings(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Only owners and admins can update settings
+	// Only owners and partners can update settings
 	role, err := h.svc.GetUserRole(r.Context(), userID, tenantID)
 	if err != nil {
 		jsonError(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-	if role != "owner" && role != "admin" {
-		jsonError(w, "only owners and admins can update settings", http.StatusForbidden)
+	if role != "owner" && role != "partner" {
+		jsonError(w, "only owners and partners can update settings", http.StatusForbidden)
 		return
 	}
 
@@ -270,6 +275,85 @@ func (h *TenantHandler) ListMembers(w http.ResponseWriter, r *http.Request) {
 	jsonResponse(w, members, http.StatusOK)
 }
 
+// UpdateMemberRole handles PUT /api/tenants/{id}/members/{uid}/role
+func (h *TenantHandler) UpdateMemberRole(w http.ResponseWriter, r *http.Request) {
+	userID, ok := auth.UserFromContext(r.Context())
+	if !ok {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	tenantID, err := uuid.Parse(r.PathValue("id"))
+	if err != nil {
+		jsonError(w, "invalid tenant ID", http.StatusBadRequest)
+		return
+	}
+
+	memberID, err := uuid.Parse(r.PathValue("uid"))
+	if err != nil {
+		jsonError(w, "invalid member ID", http.StatusBadRequest)
+		return
+	}
+
+	// Only owners and partners can change roles
+	role, err := h.svc.GetUserRole(r.Context(), userID, tenantID)
+	if err != nil {
+		jsonError(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	if role != "owner" && role != "partner" {
+		jsonError(w, "only owners and partners can change roles", http.StatusForbidden)
+		return
+	}
+
+	var req struct {
+		Role string `json:"role"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		jsonError(w, "invalid request body", http.StatusBadRequest)
+		return
+	}
+	if !auth.IsValidRole(req.Role) {
+		jsonError(w, "invalid role", http.StatusBadRequest)
+		return
+	}
+
+	// Non-owners cannot promote to owner
+	if role != "owner" && req.Role == "owner" {
+		jsonError(w, "only owners can promote to owner", http.StatusForbidden)
+		return
+	}
+
+	if err := h.svc.UpdateMemberRole(r.Context(), tenantID, memberID, req.Role); err != nil {
+		jsonError(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	jsonResponse(w, map[string]string{"status": "updated"}, http.StatusOK)
+}
+
+// GetMe handles GET /api/me — returns the current user's ID and role in the active tenant.
+func (h *TenantHandler) GetMe(w http.ResponseWriter, r *http.Request) {
+	userID, ok := auth.UserFromContext(r.Context())
+	if !ok {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	role := auth.UserRoleFromContext(r.Context())
+	tenantID, _ := auth.TenantFromContext(r.Context())
+
+	// Get user's permissions for frontend UI
+	perms := auth.GetRolePermissions(role)
+
+	jsonResponse(w, map[string]any{
+		"user_id":     userID,
+		"tenant_id":   tenantID,
+		"role":        role,
+		"permissions": perms,
+	}, http.StatusOK)
+}
+
 func jsonResponse(w http.ResponseWriter, data interface{}, status int) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(status)

backend/internal/models/case_assignment.go

@@ -0,0 +1,15 @@
+package models
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+)
+
+type CaseAssignment struct {
+	ID         uuid.UUID `db:"id" json:"id"`
+	CaseID     uuid.UUID `db:"case_id" json:"case_id"`
+	UserID     uuid.UUID `db:"user_id" json:"user_id"`
+	Role       string    `db:"role" json:"role"`
+	AssignedAt time.Time `db:"assigned_at" json:"assigned_at"`
+}

backend/internal/router/router.go

@@ -29,6 +29,7 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	calculator := services.NewDeadlineCalculator(holidaySvc)
 	storageCli := services.NewStorageClient(cfg.SupabaseURL, cfg.SupabaseServiceKey)
 	documentSvc := services.NewDocumentService(db, storageCli)
+	assignmentSvc := services.NewCaseAssignmentService(db)
 
 	// AI service (optional — only if API key is configured)
 	var aiH *handlers.AIHandler
@@ -55,6 +56,7 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	noteH := handlers.NewNoteHandler(noteSvc)
 	eventH := handlers.NewCaseEventHandler(db)
 	docH := handlers.NewDocumentHandler(documentSvc)
+	assignmentH := handlers.NewCaseAssignmentHandler(assignmentSvc)
 
 	// Public routes
 	mux.HandleFunc("GET /health", handleHealth(db))
@@ -70,77 +72,100 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	api.HandleFunc("POST /api/tenants/{id}/invite", tenantH.InviteUser)
 	api.HandleFunc("DELETE /api/tenants/{id}/members/{uid}", tenantH.RemoveMember)
 	api.HandleFunc("GET /api/tenants/{id}/members", tenantH.ListMembers)
+	api.HandleFunc("PUT /api/tenants/{id}/members/{uid}/role", tenantH.UpdateMemberRole)
+
+	// Permission-wrapping helper: wraps a HandlerFunc with a permission check
+	perm := func(p auth.Permission, fn http.HandlerFunc) http.HandlerFunc {
+		return func(w http.ResponseWriter, r *http.Request) {
+			role := auth.UserRoleFromContext(r.Context())
+			if !auth.HasPermission(role, p) {
+				w.Header().Set("Content-Type", "application/json")
+				w.WriteHeader(http.StatusForbidden)
+				w.Write([]byte(`{"error":"insufficient permissions"}`))
+				return
+			}
+			fn(w, r)
+		}
+	}
 
 	// Tenant-scoped routes (require tenant context)
 	scoped := http.NewServeMux()
 
-	// Cases
-	scoped.HandleFunc("GET /api/cases", caseH.List)
-	scoped.HandleFunc("POST /api/cases", caseH.Create)
-	scoped.HandleFunc("GET /api/cases/{id}", caseH.Get)
-	scoped.HandleFunc("PUT /api/cases/{id}", caseH.Update)
-	scoped.HandleFunc("DELETE /api/cases/{id}", caseH.Delete)
+	// Current user info (role, permissions) — all authenticated users
+	scoped.HandleFunc("GET /api/me", tenantH.GetMe)
 
-	// Parties
+	// Cases — all can view, create needs PermCreateCase, archive needs PermCreateCase
+	scoped.HandleFunc("GET /api/cases", caseH.List)
+	scoped.HandleFunc("POST /api/cases", perm(auth.PermCreateCase, caseH.Create))
+	scoped.HandleFunc("GET /api/cases/{id}", caseH.Get)
+	scoped.HandleFunc("PUT /api/cases/{id}", caseH.Update)    // case-level access checked in handler
+	scoped.HandleFunc("DELETE /api/cases/{id}", perm(auth.PermCreateCase, caseH.Delete))
+
+	// Parties — same access as case editing
 	scoped.HandleFunc("GET /api/cases/{id}/parties", partyH.List)
 	scoped.HandleFunc("POST /api/cases/{id}/parties", partyH.Create)
 	scoped.HandleFunc("PUT /api/parties/{partyId}", partyH.Update)
 	scoped.HandleFunc("DELETE /api/parties/{partyId}", partyH.Delete)
 
-	// Deadlines
+	// Deadlines — manage needs PermManageDeadlines, view is open
 	scoped.HandleFunc("GET /api/deadlines/{deadlineID}", deadlineH.Get)
 	scoped.HandleFunc("GET /api/deadlines", deadlineH.ListAll)
 	scoped.HandleFunc("GET /api/cases/{caseID}/deadlines", deadlineH.ListForCase)
-	scoped.HandleFunc("POST /api/cases/{caseID}/deadlines", deadlineH.Create)
-	scoped.HandleFunc("PUT /api/deadlines/{deadlineID}", deadlineH.Update)
-	scoped.HandleFunc("PATCH /api/deadlines/{deadlineID}/complete", deadlineH.Complete)
-	scoped.HandleFunc("DELETE /api/deadlines/{deadlineID}", deadlineH.Delete)
+	scoped.HandleFunc("POST /api/cases/{caseID}/deadlines", perm(auth.PermManageDeadlines, deadlineH.Create))
+	scoped.HandleFunc("PUT /api/deadlines/{deadlineID}", perm(auth.PermManageDeadlines, deadlineH.Update))
+	scoped.HandleFunc("PATCH /api/deadlines/{deadlineID}/complete", perm(auth.PermManageDeadlines, deadlineH.Complete))
+	scoped.HandleFunc("DELETE /api/deadlines/{deadlineID}", perm(auth.PermManageDeadlines, deadlineH.Delete))
 
-	// Deadline rules (reference data)
+	// Deadline rules (reference data) — all can read
 	scoped.HandleFunc("GET /api/deadline-rules", ruleH.List)
 	scoped.HandleFunc("GET /api/deadline-rules/{type}", ruleH.GetRuleTree)
 	scoped.HandleFunc("GET /api/proceeding-types", ruleH.ListProceedingTypes)
 
-	// Deadline calculator
+	// Deadline calculator — all can use
 	scoped.HandleFunc("POST /api/deadlines/calculate", calcH.Calculate)
 
-	// Appointments
+	// Appointments — all can manage (PermManageAppointments granted to all)
 	scoped.HandleFunc("GET /api/appointments/{id}", apptH.Get)
 	scoped.HandleFunc("GET /api/appointments", apptH.List)
-	scoped.HandleFunc("POST /api/appointments", apptH.Create)
-	scoped.HandleFunc("PUT /api/appointments/{id}", apptH.Update)
-	scoped.HandleFunc("DELETE /api/appointments/{id}", apptH.Delete)
+	scoped.HandleFunc("POST /api/appointments", perm(auth.PermManageAppointments, apptH.Create))
+	scoped.HandleFunc("PUT /api/appointments/{id}", perm(auth.PermManageAppointments, apptH.Update))
+	scoped.HandleFunc("DELETE /api/appointments/{id}", perm(auth.PermManageAppointments, apptH.Delete))
 
-	// Case events
+	// Case assignments — manage team required for assign/unassign
+	scoped.HandleFunc("GET /api/cases/{id}/assignments", assignmentH.List)
+	scoped.HandleFunc("POST /api/cases/{id}/assignments", perm(auth.PermManageTeam, assignmentH.Assign))
+	scoped.HandleFunc("DELETE /api/cases/{id}/assignments/{uid}", perm(auth.PermManageTeam, assignmentH.Unassign))
+
+	// Case events — all can view
 	scoped.HandleFunc("GET /api/case-events/{id}", eventH.Get)
 
-	// Notes
+	// Notes — all can manage
 	scoped.HandleFunc("GET /api/notes", noteH.List)
 	scoped.HandleFunc("POST /api/notes", noteH.Create)
 	scoped.HandleFunc("PUT /api/notes/{id}", noteH.Update)
 	scoped.HandleFunc("DELETE /api/notes/{id}", noteH.Delete)
 
-	// Dashboard
+	// Dashboard — all can view
 	scoped.HandleFunc("GET /api/dashboard", dashboardH.Get)
 
-	// Documents
+	// Documents — all can upload, delete checked in handler (own vs all)
 	scoped.HandleFunc("GET /api/cases/{id}/documents", docH.ListByCase)
-	scoped.HandleFunc("POST /api/cases/{id}/documents", docH.Upload)
+	scoped.HandleFunc("POST /api/cases/{id}/documents", perm(auth.PermUploadDocuments, docH.Upload))
 	scoped.HandleFunc("GET /api/documents/{docId}", docH.Download)
 	scoped.HandleFunc("GET /api/documents/{docId}/meta", docH.GetMeta)
-	scoped.HandleFunc("DELETE /api/documents/{docId}", docH.Delete)
+	scoped.HandleFunc("DELETE /api/documents/{docId}", docH.Delete) // permission check inside handler
 
 	// AI endpoints (rate limited: 5 req/min burst 10 per IP)
 	if aiH != nil {
 		aiLimiter := middleware.NewTokenBucket(5.0/60.0, 10)
-		scoped.HandleFunc("POST /api/ai/extract-deadlines", aiLimiter.LimitFunc(aiH.ExtractDeadlines))
-		scoped.HandleFunc("POST /api/ai/summarize-case", aiLimiter.LimitFunc(aiH.SummarizeCase))
+		scoped.HandleFunc("POST /api/ai/extract-deadlines", perm(auth.PermAIExtraction, aiLimiter.LimitFunc(aiH.ExtractDeadlines)))
+		scoped.HandleFunc("POST /api/ai/summarize-case", perm(auth.PermAIExtraction, aiLimiter.LimitFunc(aiH.SummarizeCase)))
 	}
 
-	// CalDAV sync endpoints
+	// CalDAV sync endpoints — settings permission required
 	if calDAVSvc != nil {
 		calDAVH := handlers.NewCalDAVHandler(calDAVSvc)
-		scoped.HandleFunc("POST /api/caldav/sync", calDAVH.TriggerSync)
+		scoped.HandleFunc("POST /api/caldav/sync", perm(auth.PermManageSettings, calDAVH.TriggerSync))
 		scoped.HandleFunc("GET /api/caldav/status", calDAVH.GetStatus)
 	}
 

backend/internal/services/case_assignment_service.go

@@ -0,0 +1,92 @@
+package services
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/google/uuid"
+	"github.com/jmoiron/sqlx"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/models"
+)
+
+type CaseAssignmentService struct {
+	db *sqlx.DB
+}
+
+func NewCaseAssignmentService(db *sqlx.DB) *CaseAssignmentService {
+	return &CaseAssignmentService{db: db}
+}
+
+// ListByCase returns all assignments for a case.
+func (s *CaseAssignmentService) ListByCase(ctx context.Context, tenantID, caseID uuid.UUID) ([]models.CaseAssignment, error) {
+	var assignments []models.CaseAssignment
+	err := s.db.SelectContext(ctx, &assignments,
+		`SELECT ca.id, ca.case_id, ca.user_id, ca.role, ca.assigned_at
+		 FROM case_assignments ca
+		 JOIN cases c ON c.id = ca.case_id
+		 WHERE ca.case_id = $1 AND c.tenant_id = $2
+		 ORDER BY ca.assigned_at`,
+		caseID, tenantID)
+	if err != nil {
+		return nil, fmt.Errorf("list case assignments: %w", err)
+	}
+	return assignments, nil
+}
+
+// Assign adds a user to a case with the given role.
+func (s *CaseAssignmentService) Assign(ctx context.Context, tenantID, caseID, userID uuid.UUID, role string) (*models.CaseAssignment, error) {
+	// Verify user is a member of this tenant
+	var memberExists bool
+	err := s.db.GetContext(ctx, &memberExists,
+		`SELECT EXISTS(SELECT 1 FROM user_tenants WHERE user_id = $1 AND tenant_id = $2)`,
+		userID, tenantID)
+	if err != nil {
+		return nil, fmt.Errorf("check membership: %w", err)
+	}
+	if !memberExists {
+		return nil, fmt.Errorf("user is not a member of this tenant")
+	}
+
+	// Verify case belongs to tenant
+	var caseExists bool
+	err = s.db.GetContext(ctx, &caseExists,
+		`SELECT EXISTS(SELECT 1 FROM cases WHERE id = $1 AND tenant_id = $2)`,
+		caseID, tenantID)
+	if err != nil {
+		return nil, fmt.Errorf("check case: %w", err)
+	}
+	if !caseExists {
+		return nil, fmt.Errorf("case not found")
+	}
+
+	var assignment models.CaseAssignment
+	err = s.db.QueryRowxContext(ctx,
+		`INSERT INTO case_assignments (case_id, user_id, role)
+		 VALUES ($1, $2, $3)
+		 ON CONFLICT (case_id, user_id) DO UPDATE SET role = EXCLUDED.role
+		 RETURNING id, case_id, user_id, role, assigned_at`,
+		caseID, userID, role,
+	).StructScan(&assignment)
+	if err != nil {
+		return nil, fmt.Errorf("assign user to case: %w", err)
+	}
+	return &assignment, nil
+}
+
+// Unassign removes a user from a case.
+func (s *CaseAssignmentService) Unassign(ctx context.Context, tenantID, caseID, userID uuid.UUID) error {
+	result, err := s.db.ExecContext(ctx,
+		`DELETE FROM case_assignments ca
+		 USING cases c
+		 WHERE ca.case_id = c.id AND ca.case_id = $1 AND ca.user_id = $2 AND c.tenant_id = $3`,
+		caseID, userID, tenantID)
+	if err != nil {
+		return fmt.Errorf("unassign: %w", err)
+	}
+	rows, _ := result.RowsAffected()
+	if rows == 0 {
+		return fmt.Errorf("assignment not found")
+	}
+	return nil
+}

backend/internal/services/tenant_service.go

@@ -189,6 +189,40 @@ func (s *TenantService) UpdateSettings(ctx context.Context, tenantID uuid.UUID,
 	return &tenant, nil
 }
 
+// UpdateMemberRole changes a member's role in a tenant.
+func (s *TenantService) UpdateMemberRole(ctx context.Context, tenantID, userID uuid.UUID, newRole string) error {
+	// Get current role
+	currentRole, err := s.GetUserRole(ctx, userID, tenantID)
+	if err != nil {
+		return fmt.Errorf("get current role: %w", err)
+	}
+	if currentRole == "" {
+		return fmt.Errorf("user is not a member of this tenant")
+	}
+
+	// If demoting the last owner, block it
+	if currentRole == "owner" && newRole != "owner" {
+		var ownerCount int
+		err := s.db.GetContext(ctx, &ownerCount,
+			`SELECT COUNT(*) FROM user_tenants WHERE tenant_id = $1 AND role = 'owner'`,
+			tenantID)
+		if err != nil {
+			return fmt.Errorf("count owners: %w", err)
+		}
+		if ownerCount <= 1 {
+			return fmt.Errorf("cannot demote the last owner")
+		}
+	}
+
+	_, err = s.db.ExecContext(ctx,
+		`UPDATE user_tenants SET role = $1 WHERE user_id = $2 AND tenant_id = $3`,
+		newRole, userID, tenantID)
+	if err != nil {
+		return fmt.Errorf("update role: %w", err)
+	}
+	return nil
+}
+
 // RemoveMember removes a user from a tenant. Cannot remove the last owner.
 func (s *TenantService) RemoveMember(ctx context.Context, tenantID, userID uuid.UUID) error {
 	// Check if the user being removed is an owner

frontend/src/app/(app)/cases/[id]/layout.tsx

@@ -13,6 +13,7 @@ import {
   Clock,
   FileText,
   Users,
+  UserCheck,
   StickyNote,
   AlertTriangle,
 } from "lucide-react";
@@ -43,6 +44,7 @@ const TABS = [
   { segment: "fristen", label: "Fristen", icon: Clock },
   { segment: "dokumente", label: "Dokumente", icon: FileText },
   { segment: "parteien", label: "Parteien", icon: Users },
+  { segment: "mitarbeiter", label: "Mitarbeiter", icon: UserCheck },
   { segment: "notizen", label: "Notizen", icon: StickyNote },
 ] as const;
 
@@ -51,6 +53,7 @@ const TAB_LABELS: Record<string, string> = {
   fristen: "Fristen",
   dokumente: "Dokumente",
   parteien: "Parteien",
+  mitarbeiter: "Mitarbeiter",
   notizen: "Notizen",
 };
 

frontend/src/app/(app)/cases/[id]/mitarbeiter/page.tsx

@@ -0,0 +1,9 @@
+"use client";
+
+import { useParams } from "next/navigation";
+import { CaseAssignments } from "@/components/cases/CaseAssignments";
+
+export default function CaseMitarbeiterPage() {
+  const { id } = useParams<{ id: string }>();
+  return <CaseAssignments caseId={id} />;
+}

frontend/src/app/(app)/cases/page.tsx

@@ -10,6 +10,7 @@ import { Plus, Search, FolderOpen } from "lucide-react";
 import { useState } from "react";
 import { SkeletonTable } from "@/components/ui/Skeleton";
 import { EmptyState } from "@/components/ui/EmptyState";
+import { usePermissions } from "@/lib/hooks/usePermissions";
 
 const STATUS_OPTIONS = [
   { value: "", label: "Alle Status" },
@@ -49,6 +50,8 @@ const inputClass =
 export default function CasesPage() {
   const router = useRouter();
   const searchParams = useSearchParams();
+  const { can } = usePermissions();
+  const canCreateCase = can("create_case");
 
   const [search, setSearch] = useState(searchParams.get("search") ?? "");
   const [status, setStatus] = useState(searchParams.get("status") ?? "");
@@ -86,13 +89,15 @@ export default function CasesPage() {
             {data ? `${data.total} Akten` : "\u00A0"}
           </p>
         </div>
-        <Link
-          href="/cases/new"
-          className="inline-flex w-fit items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800"
-        >
-          <Plus className="h-4 w-4" />
-          Neue Akte
-        </Link>
+        {canCreateCase && (
+          <Link
+            href="/cases/new"
+            className="inline-flex w-fit items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800"
+          >
+            <Plus className="h-4 w-4" />
+            Neue Akte
+          </Link>
+        )}
       </div>
 
       <div className="mt-4 flex flex-col gap-3 sm:flex-row sm:items-center">
@@ -145,7 +150,7 @@ export default function CasesPage() {
                 : "Erstellen Sie Ihre erste Akte, um loszulegen."
             }
             action={
-              !search && !status && !type ? (
+              !search && !status && !type && canCreateCase ? (
                 <Link
                   href="/cases/new"
                   className="inline-flex items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800"

frontend/src/components/cases/CaseAssignments.tsx

@@ -0,0 +1,180 @@
+"use client";
+
+import { useState } from "react";
+import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
+import { toast } from "sonner";
+import { UserPlus, Trash2, Users } from "lucide-react";
+import { api } from "@/lib/api";
+import type { CaseAssignment, UserTenant } from "@/lib/types";
+import { CASE_ASSIGNMENT_ROLE_LABELS } from "@/lib/types";
+import type { CaseAssignmentRole } from "@/lib/types";
+import { Skeleton } from "@/components/ui/Skeleton";
+import { EmptyState } from "@/components/ui/EmptyState";
+import { usePermissions } from "@/lib/hooks/usePermissions";
+
+export function CaseAssignments({ caseId }: { caseId: string }) {
+  const queryClient = useQueryClient();
+  const { can } = usePermissions();
+  const canManage = can("manage_team");
+
+  const tenantId =
+    typeof window !== "undefined"
+      ? localStorage.getItem("kanzlai_tenant_id")
+      : null;
+
+  const [selectedUser, setSelectedUser] = useState("");
+  const [assignRole, setAssignRole] = useState<CaseAssignmentRole>("team");
+
+  const { data, isLoading } = useQuery({
+    queryKey: ["case-assignments", caseId],
+    queryFn: () =>
+      api.get<{ assignments: CaseAssignment[]; total: number }>(
+        `/cases/${caseId}/assignments`,
+      ),
+  });
+
+  const { data: members } = useQuery({
+    queryKey: ["tenant-members", tenantId],
+    queryFn: () =>
+      api.get<UserTenant[]>(`/tenants/${tenantId}/members`),
+    enabled: !!tenantId && canManage,
+  });
+
+  const assignMutation = useMutation({
+    mutationFn: (input: { user_id: string; role: string }) =>
+      api.post(`/cases/${caseId}/assignments`, input),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["case-assignments", caseId] });
+      setSelectedUser("");
+      toast.success("Mitarbeiter zugewiesen");
+    },
+    onError: (err: { error?: string }) => {
+      toast.error(err.error || "Fehler beim Zuweisen");
+    },
+  });
+
+  const unassignMutation = useMutation({
+    mutationFn: (userId: string) =>
+      api.delete(`/cases/${caseId}/assignments/${userId}`),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["case-assignments", caseId] });
+      toast.success("Zuweisung entfernt");
+    },
+    onError: (err: { error?: string }) => {
+      toast.error(err.error || "Fehler beim Entfernen");
+    },
+  });
+
+  const assignments = data?.assignments ?? [];
+  const assignedUserIds = new Set(assignments.map((a) => a.user_id));
+  const availableMembers = (members ?? []).filter(
+    (m) => !assignedUserIds.has(m.user_id),
+  );
+
+  const handleAssign = (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!selectedUser) return;
+    assignMutation.mutate({ user_id: selectedUser, role: assignRole });
+  };
+
+  if (isLoading) {
+    return (
+      <div className="space-y-3">
+        <Skeleton className="h-10 w-full" />
+        <Skeleton className="h-10 w-full" />
+      </div>
+    );
+  }
+
+  return (
+    <div className="space-y-4">
+      <h3 className="text-sm font-semibold text-neutral-900">
+        Zugewiesene Mitarbeiter
+      </h3>
+
+      {/* Assign form — only for owners/partners */}
+      {canManage && availableMembers.length > 0 && (
+        <form onSubmit={handleAssign} className="flex flex-col gap-2 sm:flex-row">
+          <select
+            value={selectedUser}
+            onChange={(e) => setSelectedUser(e.target.value)}
+            className="flex-1 rounded-md border border-neutral-200 px-2 py-1.5 text-sm outline-none focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400"
+          >
+            <option value="">Mitarbeiter auswählen...</option>
+            {availableMembers.map((m) => (
+              <option key={m.user_id} value={m.user_id}>
+                {m.user_id.slice(0, 8)}... ({m.role})
+              </option>
+            ))}
+          </select>
+          <select
+            value={assignRole}
+            onChange={(e) => setAssignRole(e.target.value as CaseAssignmentRole)}
+            className="rounded-md border border-neutral-200 px-2 py-1.5 text-sm outline-none focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400"
+          >
+            {(Object.keys(CASE_ASSIGNMENT_ROLE_LABELS) as CaseAssignmentRole[]).map(
+              (r) => (
+                <option key={r} value={r}>
+                  {CASE_ASSIGNMENT_ROLE_LABELS[r]}
+                </option>
+              ),
+            )}
+          </select>
+          <button
+            type="submit"
+            disabled={assignMutation.isPending || !selectedUser}
+            className="inline-flex items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white hover:bg-neutral-800 disabled:opacity-50"
+          >
+            <UserPlus className="h-3.5 w-3.5" />
+            Zuweisen
+          </button>
+        </form>
+      )}
+
+      {/* Assignments list */}
+      {assignments.length > 0 ? (
+        <div className="overflow-hidden rounded-md border border-neutral-200">
+          {assignments.map((a, i) => (
+            <div
+              key={a.id}
+              className={`flex items-center justify-between px-4 py-2.5 ${
+                i < assignments.length - 1 ? "border-b border-neutral-100" : ""
+              }`}
+            >
+              <div className="flex items-center gap-3">
+                <div className="flex h-7 w-7 items-center justify-center rounded-full bg-neutral-100">
+                  <Users className="h-3.5 w-3.5 text-neutral-500" />
+                </div>
+                <div>
+                  <p className="text-sm text-neutral-900">
+                    {a.user_id.slice(0, 8)}...
+                  </p>
+                  <p className="text-xs text-neutral-500">
+                    {CASE_ASSIGNMENT_ROLE_LABELS[a.role as CaseAssignmentRole] ??
+                      a.role}
+                  </p>
+                </div>
+              </div>
+              {canManage && (
+                <button
+                  onClick={() => unassignMutation.mutate(a.user_id)}
+                  disabled={unassignMutation.isPending}
+                  className="rounded-md p-1 text-neutral-400 hover:bg-red-50 hover:text-red-600 disabled:opacity-50"
+                  title="Zuweisung entfernen"
+                >
+                  <Trash2 className="h-3.5 w-3.5" />
+                </button>
+              )}
+            </div>
+          ))}
+        </div>
+      ) : (
+        <EmptyState
+          icon={Users}
+          title="Keine Zuweisungen"
+          description="Noch keine Mitarbeiter zugewiesen."
+        />
+      )}
+    </div>
+  );
+}

frontend/src/components/layout/Sidebar.tsx

@@ -13,19 +13,32 @@ import {
   X,
 } from "lucide-react";
 import { useState, useEffect } from "react";
+import { usePermissions } from "@/lib/hooks/usePermissions";
 
-const navigation = [
+interface NavItem {
+  name: string;
+  href: string;
+  icon: typeof LayoutDashboard;
+  permission?: string;
+}
+
+const allNavigation: NavItem[] = [
   { name: "Dashboard", href: "/dashboard", icon: LayoutDashboard },
   { name: "Akten", href: "/cases", icon: FolderOpen },
   { name: "Fristen", href: "/fristen", icon: Clock },
   { name: "Termine", href: "/termine", icon: Calendar },
-  { name: "AI Analyse", href: "/ai/extract", icon: Brain },
-  { name: "Einstellungen", href: "/einstellungen", icon: Settings },
+  { name: "AI Analyse", href: "/ai/extract", icon: Brain, permission: "ai_extraction" },
+  { name: "Einstellungen", href: "/einstellungen", icon: Settings, permission: "manage_settings" },
 ];
 
 export function Sidebar() {
   const pathname = usePathname();
   const [mobileOpen, setMobileOpen] = useState(false);
+  const { can, isLoading: permLoading } = usePermissions();
+
+  const navigation = allNavigation.filter(
+    (item) => !item.permission || permLoading || can(item.permission),
+  );
 
   // Close on route change
   useEffect(() => {

frontend/src/components/settings/TeamSettings.tsx

@@ -3,27 +3,36 @@
 import { useState } from "react";
 import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
 import { toast } from "sonner";
-import { UserPlus, Trash2, Shield, Crown, User } from "lucide-react";
+import { UserPlus, Trash2, Crown, Scale, Briefcase, FileText, Phone } from "lucide-react";
 import { api } from "@/lib/api";
-import type { UserTenant } from "@/lib/types";
+import type { UserTenant, UserRole } from "@/lib/types";
+import { ROLE_LABELS } from "@/lib/types";
 import { Skeleton } from "@/components/ui/Skeleton";
 import { EmptyState } from "@/components/ui/EmptyState";
+import { usePermissions } from "@/lib/hooks/usePermissions";
 
-const ROLE_LABELS: Record<string, { label: string; icon: typeof Crown }> = {
-  owner: { label: "Eigentümer", icon: Crown },
-  admin: { label: "Administrator", icon: Shield },
-  member: { label: "Mitglied", icon: User },
+const ROLE_CONFIG: Record<UserRole, { label: string; icon: typeof Crown }> = {
+  owner: { label: ROLE_LABELS.owner, icon: Crown },
+  partner: { label: ROLE_LABELS.partner, icon: Scale },
+  associate: { label: ROLE_LABELS.associate, icon: Briefcase },
+  paralegal: { label: ROLE_LABELS.paralegal, icon: FileText },
+  secretary: { label: ROLE_LABELS.secretary, icon: Phone },
 };
 
+const INVITE_ROLES: UserRole[] = ["partner", "associate", "paralegal", "secretary"];
+
 export function TeamSettings() {
   const queryClient = useQueryClient();
+  const { can, role: myRole } = usePermissions();
   const tenantId =
     typeof window !== "undefined"
       ? localStorage.getItem("kanzlai_tenant_id")
       : null;
 
   const [email, setEmail] = useState("");
-  const [role, setRole] = useState("member");
+  const [role, setRole] = useState<string>("associate");
+
+  const canManageTeam = can("manage_team");
 
   const {
     data: members,
@@ -42,7 +51,7 @@ export function TeamSettings() {
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ["tenant-members"] });
       setEmail("");
-      setRole("member");
+      setRole("associate");
       toast.success("Benutzer eingeladen");
     },
     onError: (err: { error?: string }) => {
@@ -62,6 +71,19 @@ export function TeamSettings() {
     },
   });
 
+  const updateRoleMutation = useMutation({
+    mutationFn: ({ userId, newRole }: { userId: string; newRole: string }) =>
+      api.put(`/tenants/${tenantId}/members/${userId}/role`, { role: newRole }),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["tenant-members"] });
+      queryClient.invalidateQueries({ queryKey: ["me"] });
+      toast.success("Rolle aktualisiert");
+    },
+    onError: (err: { error?: string }) => {
+      toast.error(err.error || "Fehler beim Aktualisieren der Rolle");
+    },
+  });
+
   const handleInvite = (e: React.FormEvent) => {
     e.preventDefault();
     if (!email.trim()) return;
@@ -81,7 +103,7 @@ export function TeamSettings() {
   if (error) {
     return (
       <EmptyState
-        icon={User}
+        icon={Briefcase}
         title="Fehler beim Laden"
         description="Team-Mitglieder konnten nicht geladen werden."
       />
@@ -90,38 +112,44 @@ export function TeamSettings() {
 
   return (
     <div className="space-y-6">
-      {/* Invite Form */}
-      <form onSubmit={handleInvite} className="flex flex-col gap-3 sm:flex-row">
-        <input
-          type="email"
-          value={email}
-          onChange={(e) => setEmail(e.target.value)}
-          placeholder="name@example.com"
-          className="flex-1 rounded-md border border-neutral-200 px-3 py-1.5 text-sm outline-none focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400"
-        />
-        <select
-          value={role}
-          onChange={(e) => setRole(e.target.value)}
-          className="rounded-md border border-neutral-200 px-2 py-1.5 text-sm outline-none focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400"
-        >
-          <option value="member">Mitglied</option>
-          <option value="admin">Administrator</option>
-        </select>
-        <button
-          type="submit"
-          disabled={inviteMutation.isPending || !email.trim()}
-          className="inline-flex items-center gap-1.5 rounded-md bg-neutral-900 px-4 py-1.5 text-sm font-medium text-white hover:bg-neutral-800 disabled:opacity-50"
-        >
-          <UserPlus className="h-3.5 w-3.5" />
-          {inviteMutation.isPending ? "Einladen..." : "Einladen"}
-        </button>
-      </form>
+      {/* Invite Form — only for owners/partners */}
+      {canManageTeam && (
+        <form onSubmit={handleInvite} className="flex flex-col gap-3 sm:flex-row">
+          <input
+            type="email"
+            value={email}
+            onChange={(e) => setEmail(e.target.value)}
+            placeholder="name@example.com"
+            className="flex-1 rounded-md border border-neutral-200 px-3 py-1.5 text-sm outline-none focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400"
+          />
+          <select
+            value={role}
+            onChange={(e) => setRole(e.target.value)}
+            className="rounded-md border border-neutral-200 px-2 py-1.5 text-sm outline-none focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400"
+          >
+            {INVITE_ROLES.map((r) => (
+              <option key={r} value={r}>
+                {ROLE_LABELS[r]}
+              </option>
+            ))}
+          </select>
+          <button
+            type="submit"
+            disabled={inviteMutation.isPending || !email.trim()}
+            className="inline-flex items-center gap-1.5 rounded-md bg-neutral-900 px-4 py-1.5 text-sm font-medium text-white hover:bg-neutral-800 disabled:opacity-50"
+          >
+            <UserPlus className="h-3.5 w-3.5" />
+            {inviteMutation.isPending ? "Einladen..." : "Einladen"}
+          </button>
+        </form>
+      )}
 
       {/* Members List */}
       {Array.isArray(members) && members.length > 0 ? (
         <div className="overflow-hidden rounded-md border border-neutral-200">
           {members.map((member, i) => {
-            const roleInfo = ROLE_LABELS[member.role] || ROLE_LABELS.member;
+            const roleKey = (member.role as UserRole) || "associate";
+            const roleInfo = ROLE_CONFIG[roleKey] || ROLE_CONFIG.associate;
             const RoleIcon = roleInfo.icon;
             return (
               <div
@@ -141,23 +169,48 @@ export function TeamSettings() {
                     <p className="text-xs text-neutral-500">{roleInfo.label}</p>
                   </div>
                 </div>
-                {member.role !== "owner" && (
-                  <button
-                    onClick={() => removeMutation.mutate(member.user_id)}
-                    disabled={removeMutation.isPending}
-                    className="rounded-md p-1.5 text-neutral-400 hover:bg-red-50 hover:text-red-600 disabled:opacity-50"
-                    title="Mitglied entfernen"
-                  >
-                    <Trash2 className="h-4 w-4" />
-                  </button>
-                )}
+                <div className="flex items-center gap-2">
+                  {/* Role dropdown — only for owners/partners, not for the member's own row if they are owner */}
+                  {canManageTeam && member.role !== "owner" && (
+                    <select
+                      value={member.role}
+                      onChange={(e) =>
+                        updateRoleMutation.mutate({
+                          userId: member.user_id,
+                          newRole: e.target.value,
+                        })
+                      }
+                      disabled={updateRoleMutation.isPending}
+                      className="rounded-md border border-neutral-200 px-2 py-1 text-xs outline-none focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400"
+                    >
+                      {myRole === "owner" && (
+                        <option value="owner">{ROLE_LABELS.owner}</option>
+                      )}
+                      {INVITE_ROLES.map((r) => (
+                        <option key={r} value={r}>
+                          {ROLE_LABELS[r]}
+                        </option>
+                      ))}
+                    </select>
+                  )}
+                  {canManageTeam && member.role !== "owner" && (
+                    <button
+                      onClick={() => removeMutation.mutate(member.user_id)}
+                      disabled={removeMutation.isPending}
+                      className="rounded-md p-1.5 text-neutral-400 hover:bg-red-50 hover:text-red-600 disabled:opacity-50"
+                      title="Mitglied entfernen"
+                    >
+                      <Trash2 className="h-4 w-4" />
+                    </button>
+                  )}
+                </div>
               </div>
             );
           })}
         </div>
       ) : (
         <EmptyState
-          icon={User}
+          icon={Briefcase}
           title="Noch keine Mitglieder"
           description="Laden Sie Teammitglieder per E-Mail ein."
         />

frontend/src/lib/hooks/usePermissions.ts

@@ -0,0 +1,29 @@
+"use client";
+
+import { useQuery } from "@tanstack/react-query";
+import { api } from "@/lib/api";
+import type { UserInfo } from "@/lib/types";
+
+export function usePermissions() {
+  const { data, isLoading } = useQuery({
+    queryKey: ["me"],
+    queryFn: () => api.get<UserInfo>("/me"),
+    staleTime: 60 * 1000,
+  });
+
+  const role = data?.role ?? null;
+  const permissions = data?.permissions ?? [];
+
+  function can(permission: string): boolean {
+    return permissions.includes(permission);
+  }
+
+  return {
+    role,
+    permissions,
+    can,
+    isLoading,
+    userId: data?.user_id ?? null,
+    tenantId: data?.tenant_id ?? null,
+  };
+}

frontend/src/lib/types.ts

@@ -189,6 +189,40 @@ export interface Note {
   updated_at: string;
 }
 
+export interface CaseAssignment {
+  id: string;
+  case_id: string;
+  user_id: string;
+  role: string;
+  assigned_at: string;
+}
+
+export interface UserInfo {
+  user_id: string;
+  tenant_id: string;
+  role: UserRole;
+  permissions: string[];
+}
+
+export type UserRole = "owner" | "partner" | "associate" | "paralegal" | "secretary";
+
+export const ROLE_LABELS: Record<UserRole, string> = {
+  owner: "Inhaber",
+  partner: "Partner",
+  associate: "Anwalt",
+  paralegal: "Paralegal",
+  secretary: "Sekretariat",
+};
+
+export const CASE_ASSIGNMENT_ROLES = ["lead", "team", "viewer"] as const;
+export type CaseAssignmentRole = (typeof CASE_ASSIGNMENT_ROLES)[number];
+
+export const CASE_ASSIGNMENT_ROLE_LABELS: Record<CaseAssignmentRole, string> = {
+  lead: "Federführend",
+  team: "Team",
+  viewer: "Einsicht",
+};
+
 export interface ApiError {
   error: string;
   status: number;