# 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.

---

## 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 ./`.

---

## 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)
- [ ] 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)
- [ ] 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.*