feat: time tracking + billing — hourly rates, time entries, invoices (P1)

Database: time_entries, billing_rates, invoices tables with RLS. Backend: CRUD services+handlers for time entries, billing rates, invoices. - Time entries: list/create/update/delete, summary by case/user/month - Billing rates: upsert with auto-close previous, current rate lookup - Invoices: create with auto-number (RE-YYYY-NNN), status transitions (draft->sent->paid, cancellation), link time entries on invoice create API: 11 new endpoints under /api/time-entries, /api/billing-rates, /api/invoices Frontend: Zeiterfassung tab on case detail, /abrechnung overview with filters, /abrechnung/rechnungen list+detail with status actions, billing rates settings Also: resolved merge conflicts between audit-trail and role-based branches, added missing types (Notification, AuditLogResponse, NotificationPreferences)
2026-03-30 11:24:36 +02:00
30 changed files with 2339 additions and 1649 deletions
--- a/backend/cmd/server/main.go
+++ b/backend/cmd/server/main.go
@@ -5,9 +5,6 @@ import (
 	"net/http"
 	"os"

-	"github.com/jmoiron/sqlx"
-	_ "github.com/lib/pq"
-
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/config"
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/db"
@@ -34,21 +31,6 @@ func main() {

 	authMW := auth.NewMiddleware(cfg.SupabaseJWTSecret, database)

-	// Optional: connect to youpc.org database for similar case finder
-	var youpcDB *sqlx.DB
-	if cfg.YouPCDatabaseURL != "" {
-		youpcDB, err = sqlx.Connect("postgres", cfg.YouPCDatabaseURL)
-		if err != nil {
-			slog.Warn("failed to connect to youpc.org database — similar case finder disabled", "error", err)
-			youpcDB = nil
-		} else {
-			youpcDB.SetMaxOpenConns(5)
-			youpcDB.SetMaxIdleConns(2)
-			defer youpcDB.Close()
-			slog.Info("connected to youpc.org database for similar case finder")
-		}
-	}
-
 	// Start CalDAV sync service
 	calDAVSvc := services.NewCalDAVService(database)
 	calDAVSvc.Start()
@@ -59,7 +41,7 @@ func main() {
 	notifSvc.Start()
 	defer notifSvc.Stop()

-	handler := router.New(database, authMW, cfg, calDAVSvc, notifSvc, youpcDB)
+	handler := router.New(database, authMW, cfg, calDAVSvc, notifSvc)

 	slog.Info("starting KanzlAI API server", "port", cfg.Port)
 	if err := http.ListenAndServe(":"+cfg.Port, handler); err != nil {
--- a/backend/internal/auth/middleware.go
+++ b/backend/internal/auth/middleware.go
@@ -45,6 +45,7 @@ func (m *Middleware) RequireAuth(next http.Handler) http.Handler {

 		// Tenant resolution is handled by TenantResolver middleware for scoped routes.
 		// Tenant management routes handle their own access control.
+
 		next.ServeHTTP(w, r.WithContext(ctx))
 	})
 }
--- a/backend/internal/auth/tenant_resolver.go
+++ b/backend/internal/auth/tenant_resolver.go
@@ -58,7 +58,7 @@ func (tr *TenantResolver) Resolve(next http.Handler) http.Handler {
 			tenantID = parsed
 			r = r.WithContext(ContextWithUserRole(r.Context(), role))
 		} else {
-			// Default to user's first tenant (role already set by middleware)
+			// Default to user's first tenant
 			first, err := tr.lookup.FirstTenantForUser(r.Context(), userID)
 			if err != nil {
 				slog.Error("failed to resolve default tenant", "error", err, "user_id", userID)
@@ -70,6 +70,15 @@ func (tr *TenantResolver) Resolve(next http.Handler) http.Handler {
 				return
 			}
 			tenantID = *first
+
+			// Also resolve role for default tenant
+			role, err := tr.lookup.GetUserRole(r.Context(), userID, tenantID)
+			if err != nil {
+				slog.Error("failed to get role for default tenant", "error", err, "user_id", userID, "tenant_id", tenantID)
+				http.Error(w, `{"error":"internal error"}`, http.StatusInternalServerError)
+				return
+			}
+			r = r.WithContext(ContextWithUserRole(r.Context(), role))
 		}

 		ctx := ContextWithTenantID(r.Context(), tenantID)
--- a/backend/internal/auth/tenant_resolver_test.go
+++ b/backend/internal/auth/tenant_resolver_test.go
@@ -15,7 +15,6 @@ type mockTenantLookup struct {
 	hasAccess bool
 	accessErr error
 	role      string
-	noAccess  bool // when true, GetUserRole returns ""
 }

 func (m *mockTenantLookup) FirstTenantForUser(ctx context.Context, userID uuid.UUID) (*uuid.UUID, error) {
@@ -27,18 +26,18 @@ func (m *mockTenantLookup) VerifyAccess(ctx context.Context, userID, tenantID uu
 }

 func (m *mockTenantLookup) GetUserRole(ctx context.Context, userID, tenantID uuid.UUID) (string, error) {
-	if m.noAccess {
-		return "", m.err
-	}
 	if m.role != "" {
 		return m.role, m.err
 	}
-	return "associate", m.err
+	if m.hasAccess {
+		return "associate", m.err
+	}
+	return "", m.err
 }

 func TestTenantResolver_FromHeader(t *testing.T) {
 	tenantID := uuid.New()
-	tr := NewTenantResolver(&mockTenantLookup{role: "partner", hasAccess: true})
+	tr := NewTenantResolver(&mockTenantLookup{hasAccess: true, role: "partner"})

 	var gotTenantID uuid.UUID
 	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
@@ -67,7 +66,7 @@ func TestTenantResolver_FromHeader(t *testing.T) {

 func TestTenantResolver_FromHeader_NoAccess(t *testing.T) {
 	tenantID := uuid.New()
-	tr := NewTenantResolver(&mockTenantLookup{noAccess: true})
+	tr := NewTenantResolver(&mockTenantLookup{hasAccess: false})

 	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		t.Fatal("next should not be called")
@@ -87,7 +86,7 @@ func TestTenantResolver_FromHeader_NoAccess(t *testing.T) {

 func TestTenantResolver_DefaultsToFirst(t *testing.T) {
 	tenantID := uuid.New()
-	tr := NewTenantResolver(&mockTenantLookup{tenantID: &tenantID})
+	tr := NewTenantResolver(&mockTenantLookup{tenantID: &tenantID, role: "owner"})

 	var gotTenantID uuid.UUID
 	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
--- a/backend/internal/config/config.go
+++ b/backend/internal/config/config.go
@@ -14,7 +14,6 @@ type Config struct {
 	SupabaseJWTSecret string
 	AnthropicAPIKey   string
 	FrontendOrigin    string
-	YouPCDatabaseURL  string // read-only connection to youpc.org Supabase for similar case finder
 }

 func Load() (*Config, error) {
@@ -27,7 +26,6 @@ func Load() (*Config, error) {
 		SupabaseJWTSecret: os.Getenv("SUPABASE_JWT_SECRET"),
 		AnthropicAPIKey:  os.Getenv("ANTHROPIC_API_KEY"),
 		FrontendOrigin:   getEnv("FRONTEND_ORIGIN", "https://kanzlai.msbls.de"),
-		YouPCDatabaseURL: os.Getenv("YOUPC_DATABASE_URL"),
 	}

 	if cfg.DatabaseURL == "" {
--- a/backend/internal/handlers/ai.go
+++ b/backend/internal/handlers/ai.go
@@ -5,8 +5,6 @@ import (
 	"io"
 	"net/http"

-	"github.com/google/uuid"
-
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
 )
@@ -117,139 +115,3 @@ func (h *AIHandler) SummarizeCase(w http.ResponseWriter, r *http.Request) {
 		"summary": summary,
 	})
 }
-
-// DraftDocument handles POST /api/ai/draft-document
-// Accepts JSON {"case_id": "uuid", "template_type": "string", "instructions": "string", "language": "de|en|fr"}.
-func (h *AIHandler) DraftDocument(w http.ResponseWriter, r *http.Request) {
-	tenantID, ok := auth.TenantFromContext(r.Context())
-	if !ok {
-		writeError(w, http.StatusForbidden, "missing tenant")
-		return
-	}
-
-	var body struct {
-		CaseID       string `json:"case_id"`
-		TemplateType string `json:"template_type"`
-		Instructions string `json:"instructions"`
-		Language     string `json:"language"`
-	}
-	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
-		writeError(w, http.StatusBadRequest, "invalid request body")
-		return
-	}
-
-	if body.CaseID == "" {
-		writeError(w, http.StatusBadRequest, "case_id is required")
-		return
-	}
-	if body.TemplateType == "" {
-		writeError(w, http.StatusBadRequest, "template_type is required")
-		return
-	}
-
-	caseID, err := parseUUID(body.CaseID)
-	if err != nil {
-		writeError(w, http.StatusBadRequest, "invalid case_id")
-		return
-	}
-
-	if len(body.Instructions) > maxDescriptionLen {
-		writeError(w, http.StatusBadRequest, "instructions exceeds maximum length")
-		return
-	}
-
-	draft, err := h.ai.DraftDocument(r.Context(), tenantID, caseID, body.TemplateType, body.Instructions, body.Language)
-	if err != nil {
-		internalError(w, "AI document drafting failed", err)
-		return
-	}
-
-	writeJSON(w, http.StatusOK, draft)
-}
-
-// CaseStrategy handles POST /api/ai/case-strategy
-// Accepts JSON {"case_id": "uuid"}.
-func (h *AIHandler) CaseStrategy(w http.ResponseWriter, r *http.Request) {
-	tenantID, ok := auth.TenantFromContext(r.Context())
-	if !ok {
-		writeError(w, http.StatusForbidden, "missing tenant")
-		return
-	}
-
-	var body struct {
-		CaseID string `json:"case_id"`
-	}
-	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
-		writeError(w, http.StatusBadRequest, "invalid request body")
-		return
-	}
-
-	if body.CaseID == "" {
-		writeError(w, http.StatusBadRequest, "case_id is required")
-		return
-	}
-
-	caseID, err := parseUUID(body.CaseID)
-	if err != nil {
-		writeError(w, http.StatusBadRequest, "invalid case_id")
-		return
-	}
-
-	strategy, err := h.ai.CaseStrategy(r.Context(), tenantID, caseID)
-	if err != nil {
-		internalError(w, "AI case strategy analysis failed", err)
-		return
-	}
-
-	writeJSON(w, http.StatusOK, strategy)
-}
-
-// SimilarCases handles POST /api/ai/similar-cases
-// Accepts JSON {"case_id": "uuid", "description": "string"}.
-func (h *AIHandler) SimilarCases(w http.ResponseWriter, r *http.Request) {
-	tenantID, ok := auth.TenantFromContext(r.Context())
-	if !ok {
-		writeError(w, http.StatusForbidden, "missing tenant")
-		return
-	}
-
-	var body struct {
-		CaseID      string `json:"case_id"`
-		Description string `json:"description"`
-	}
-	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
-		writeError(w, http.StatusBadRequest, "invalid request body")
-		return
-	}
-
-	if body.CaseID == "" && body.Description == "" {
-		writeError(w, http.StatusBadRequest, "either case_id or description is required")
-		return
-	}
-
-	if len(body.Description) > maxDescriptionLen {
-		writeError(w, http.StatusBadRequest, "description exceeds maximum length")
-		return
-	}
-
-	var caseID uuid.UUID
-	if body.CaseID != "" {
-		var err error
-		caseID, err = parseUUID(body.CaseID)
-		if err != nil {
-			writeError(w, http.StatusBadRequest, "invalid case_id")
-			return
-		}
-	}
-
-	cases, err := h.ai.FindSimilarCases(r.Context(), tenantID, caseID, body.Description)
-	if err != nil {
-		internalError(w, "AI similar case search failed", err)
-		return
-	}
-
-	writeJSON(w, http.StatusOK, map[string]any{
-		"cases": cases,
-		"count": len(cases),
-	})
-}
--- a/backend/internal/handlers/billing_rates.go
+++ b/backend/internal/handlers/billing_rates.go
@@ -0,0 +1,66 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
+)
+
+type BillingRateHandler struct {
+	svc *services.BillingRateService
+}
+
+func NewBillingRateHandler(svc *services.BillingRateService) *BillingRateHandler {
+	return &BillingRateHandler{svc: svc}
+}
+
+// List handles GET /api/billing-rates
+func (h *BillingRateHandler) List(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	rates, err := h.svc.List(r.Context(), tenantID)
+	if err != nil {
+		internalError(w, "failed to list billing rates", err)
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{"billing_rates": rates})
+}
+
+// Upsert handles PUT /api/billing-rates
+func (h *BillingRateHandler) Upsert(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	var input services.UpsertBillingRateInput
+	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON body")
+		return
+	}
+
+	if input.Rate < 0 {
+		writeError(w, http.StatusBadRequest, "rate must be non-negative")
+		return
+	}
+	if input.ValidFrom == "" {
+		writeError(w, http.StatusBadRequest, "valid_from is required")
+		return
+	}
+
+	rate, err := h.svc.Upsert(r.Context(), tenantID, input)
+	if err != nil {
+		internalError(w, "failed to upsert billing rate", err)
+		return
+	}
+
+	writeJSON(w, http.StatusOK, rate)
+}
--- a/backend/internal/handlers/deadlines.go
+++ b/backend/internal/handlers/deadlines.go
@@ -198,8 +198,9 @@ func (h *DeadlineHandlers) Delete(w http.ResponseWriter, r *http.Request) {
 		return
 	}

-	if err := h.deadlines.Delete(r.Context(), tenantID, deadlineID); err != nil {
-		writeError(w, http.StatusNotFound, "deadline not found")
+	err = h.deadlines.Delete(r.Context(), tenantID, deadlineID)
+	if err != nil {
+		writeError(w, http.StatusNotFound, err.Error())
 		return
 	}

--- a/backend/internal/handlers/invoices.go
+++ b/backend/internal/handlers/invoices.go
@@ -0,0 +1,170 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
+
+	"github.com/google/uuid"
+)
+
+type InvoiceHandler struct {
+	svc *services.InvoiceService
+}
+
+func NewInvoiceHandler(svc *services.InvoiceService) *InvoiceHandler {
+	return &InvoiceHandler{svc: svc}
+}
+
+// List handles GET /api/invoices?case_id=&status=
+func (h *InvoiceHandler) List(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	var caseID *uuid.UUID
+	if caseStr := r.URL.Query().Get("case_id"); caseStr != "" {
+		parsed, err := uuid.Parse(caseStr)
+		if err != nil {
+			writeError(w, http.StatusBadRequest, "invalid case_id")
+			return
+		}
+		caseID = &parsed
+	}
+
+	invoices, err := h.svc.List(r.Context(), tenantID, caseID, r.URL.Query().Get("status"))
+	if err != nil {
+		internalError(w, "failed to list invoices", err)
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{"invoices": invoices})
+}
+
+// Get handles GET /api/invoices/{id}
+func (h *InvoiceHandler) Get(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	invoiceID, err := parsePathUUID(r, "id")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid invoice ID")
+		return
+	}
+
+	inv, err := h.svc.GetByID(r.Context(), tenantID, invoiceID)
+	if err != nil {
+		internalError(w, "failed to get invoice", err)
+		return
+	}
+	if inv == nil {
+		writeError(w, http.StatusNotFound, "invoice not found")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, inv)
+}
+
+// Create handles POST /api/invoices
+func (h *InvoiceHandler) Create(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+	userID, _ := auth.UserFromContext(r.Context())
+
+	var input services.CreateInvoiceInput
+	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON body")
+		return
+	}
+
+	if input.ClientName == "" {
+		writeError(w, http.StatusBadRequest, "client_name is required")
+		return
+	}
+	if input.CaseID == uuid.Nil {
+		writeError(w, http.StatusBadRequest, "case_id is required")
+		return
+	}
+
+	inv, err := h.svc.Create(r.Context(), tenantID, userID, input)
+	if err != nil {
+		internalError(w, "failed to create invoice", err)
+		return
+	}
+
+	writeJSON(w, http.StatusCreated, inv)
+}
+
+// Update handles PUT /api/invoices/{id}
+func (h *InvoiceHandler) Update(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	invoiceID, err := parsePathUUID(r, "id")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid invoice ID")
+		return
+	}
+
+	var input services.UpdateInvoiceInput
+	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON body")
+		return
+	}
+
+	inv, err := h.svc.Update(r.Context(), tenantID, invoiceID, input)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusOK, inv)
+}
+
+// UpdateStatus handles PATCH /api/invoices/{id}/status
+func (h *InvoiceHandler) UpdateStatus(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	invoiceID, err := parsePathUUID(r, "id")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid invoice ID")
+		return
+	}
+
+	var body struct {
+		Status string `json:"status"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON body")
+		return
+	}
+	if body.Status == "" {
+		writeError(w, http.StatusBadRequest, "status is required")
+		return
+	}
+
+	inv, err := h.svc.UpdateStatus(r.Context(), tenantID, invoiceID, body.Status)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusOK, inv)
+}
--- a/backend/internal/handlers/time_entries.go
+++ b/backend/internal/handlers/time_entries.go
@@ -0,0 +1,209 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+	"strconv"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
+
+	"github.com/google/uuid"
+)
+
+type TimeEntryHandler struct {
+	svc *services.TimeEntryService
+}
+
+func NewTimeEntryHandler(svc *services.TimeEntryService) *TimeEntryHandler {
+	return &TimeEntryHandler{svc: svc}
+}
+
+// ListForCase handles GET /api/cases/{id}/time-entries
+func (h *TimeEntryHandler) ListForCase(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	caseID, err := parsePathUUID(r, "id")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid case ID")
+		return
+	}
+
+	entries, err := h.svc.ListForCase(r.Context(), tenantID, caseID)
+	if err != nil {
+		internalError(w, "failed to list time entries", err)
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{"time_entries": entries})
+}
+
+// List handles GET /api/time-entries?case_id=&user_id=&from=&to=
+func (h *TimeEntryHandler) List(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
+	offset, _ := strconv.Atoi(r.URL.Query().Get("offset"))
+	limit, offset = clampPagination(limit, offset)
+
+	filter := services.TimeEntryFilter{
+		From:   r.URL.Query().Get("from"),
+		To:     r.URL.Query().Get("to"),
+		Limit:  limit,
+		Offset: offset,
+	}
+
+	if caseStr := r.URL.Query().Get("case_id"); caseStr != "" {
+		caseID, err := uuid.Parse(caseStr)
+		if err != nil {
+			writeError(w, http.StatusBadRequest, "invalid case_id")
+			return
+		}
+		filter.CaseID = &caseID
+	}
+	if userStr := r.URL.Query().Get("user_id"); userStr != "" {
+		userID, err := uuid.Parse(userStr)
+		if err != nil {
+			writeError(w, http.StatusBadRequest, "invalid user_id")
+			return
+		}
+		filter.UserID = &userID
+	}
+
+	entries, total, err := h.svc.List(r.Context(), tenantID, filter)
+	if err != nil {
+		internalError(w, "failed to list time entries", err)
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"time_entries": entries,
+		"total":        total,
+	})
+}
+
+// Create handles POST /api/cases/{id}/time-entries
+func (h *TimeEntryHandler) Create(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+	userID, _ := auth.UserFromContext(r.Context())
+
+	caseID, err := parsePathUUID(r, "id")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid case ID")
+		return
+	}
+
+	var input services.CreateTimeEntryInput
+	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON body")
+		return
+	}
+	input.CaseID = caseID
+
+	if input.Description == "" {
+		writeError(w, http.StatusBadRequest, "description is required")
+		return
+	}
+	if input.DurationMinutes <= 0 {
+		writeError(w, http.StatusBadRequest, "duration_minutes must be positive")
+		return
+	}
+	if input.Date == "" {
+		writeError(w, http.StatusBadRequest, "date is required")
+		return
+	}
+
+	entry, err := h.svc.Create(r.Context(), tenantID, userID, input)
+	if err != nil {
+		internalError(w, "failed to create time entry", err)
+		return
+	}
+
+	writeJSON(w, http.StatusCreated, entry)
+}
+
+// Update handles PUT /api/time-entries/{id}
+func (h *TimeEntryHandler) Update(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	entryID, err := parsePathUUID(r, "id")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid time entry ID")
+		return
+	}
+
+	var input services.UpdateTimeEntryInput
+	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON body")
+		return
+	}
+
+	entry, err := h.svc.Update(r.Context(), tenantID, entryID, input)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusOK, entry)
+}
+
+// Delete handles DELETE /api/time-entries/{id}
+func (h *TimeEntryHandler) Delete(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	entryID, err := parsePathUUID(r, "id")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid time entry ID")
+		return
+	}
+
+	if err := h.svc.Delete(r.Context(), tenantID, entryID); err != nil {
+		writeError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]string{"status": "deleted"})
+}
+
+// Summary handles GET /api/time-entries/summary?group_by=case|user|month&from=&to=
+func (h *TimeEntryHandler) Summary(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	groupBy := r.URL.Query().Get("group_by")
+	if groupBy == "" {
+		groupBy = "case"
+	}
+
+	summaries, err := h.svc.Summary(r.Context(), tenantID, groupBy,
+		r.URL.Query().Get("from"), r.URL.Query().Get("to"))
+	if err != nil {
+		internalError(w, "failed to get summary", err)
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{"summary": summaries})
+}
--- a/backend/internal/models/billing_rate.go
+++ b/backend/internal/models/billing_rate.go
@@ -0,0 +1,18 @@
+package models
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+)
+
+type BillingRate struct {
+	ID        uuid.UUID  `db:"id" json:"id"`
+	TenantID  uuid.UUID  `db:"tenant_id" json:"tenant_id"`
+	UserID    *uuid.UUID `db:"user_id" json:"user_id,omitempty"`
+	Rate      float64    `db:"rate" json:"rate"`
+	Currency  string     `db:"currency" json:"currency"`
+	ValidFrom string     `db:"valid_from" json:"valid_from"`
+	ValidTo   *string    `db:"valid_to" json:"valid_to,omitempty"`
+	CreatedAt time.Time  `db:"created_at" json:"created_at"`
+}
--- a/backend/internal/models/invoice.go
+++ b/backend/internal/models/invoice.go
@@ -0,0 +1,38 @@
+package models
+
+import (
+	"encoding/json"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+type Invoice struct {
+	ID            uuid.UUID       `db:"id" json:"id"`
+	TenantID      uuid.UUID       `db:"tenant_id" json:"tenant_id"`
+	CaseID        uuid.UUID       `db:"case_id" json:"case_id"`
+	InvoiceNumber string          `db:"invoice_number" json:"invoice_number"`
+	ClientName    string          `db:"client_name" json:"client_name"`
+	ClientAddress *string         `db:"client_address" json:"client_address,omitempty"`
+	Items         json.RawMessage `db:"items" json:"items"`
+	Subtotal      float64         `db:"subtotal" json:"subtotal"`
+	TaxRate       float64         `db:"tax_rate" json:"tax_rate"`
+	TaxAmount     float64         `db:"tax_amount" json:"tax_amount"`
+	Total         float64         `db:"total" json:"total"`
+	Status        string          `db:"status" json:"status"`
+	IssuedAt      *string         `db:"issued_at" json:"issued_at,omitempty"`
+	DueAt         *string         `db:"due_at" json:"due_at,omitempty"`
+	PaidAt        *time.Time      `db:"paid_at" json:"paid_at,omitempty"`
+	Notes         *string         `db:"notes" json:"notes,omitempty"`
+	CreatedBy     uuid.UUID       `db:"created_by" json:"created_by"`
+	CreatedAt     time.Time       `db:"created_at" json:"created_at"`
+	UpdatedAt     time.Time       `db:"updated_at" json:"updated_at"`
+}
+
+type InvoiceItem struct {
+	Description     string  `json:"description"`
+	DurationMinutes int     `json:"duration_minutes,omitempty"`
+	HourlyRate      float64 `json:"hourly_rate,omitempty"`
+	Amount          float64 `json:"amount"`
+	TimeEntryID     *string `json:"time_entry_id,omitempty"`
+}
--- a/backend/internal/models/time_entry.go
+++ b/backend/internal/models/time_entry.go
@@ -0,0 +1,24 @@
+package models
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+)
+
+type TimeEntry struct {
+	ID              uuid.UUID  `db:"id" json:"id"`
+	TenantID        uuid.UUID  `db:"tenant_id" json:"tenant_id"`
+	CaseID          uuid.UUID  `db:"case_id" json:"case_id"`
+	UserID          uuid.UUID  `db:"user_id" json:"user_id"`
+	Date            string     `db:"date" json:"date"`
+	DurationMinutes int        `db:"duration_minutes" json:"duration_minutes"`
+	Description     string     `db:"description" json:"description"`
+	Activity        *string    `db:"activity" json:"activity,omitempty"`
+	Billable        bool       `db:"billable" json:"billable"`
+	Billed          bool       `db:"billed" json:"billed"`
+	InvoiceID       *uuid.UUID `db:"invoice_id" json:"invoice_id,omitempty"`
+	HourlyRate      *float64   `db:"hourly_rate" json:"hourly_rate,omitempty"`
+	CreatedAt       time.Time  `db:"created_at" json:"created_at"`
+	UpdatedAt       time.Time  `db:"updated_at" json:"updated_at"`
+}
--- a/backend/internal/router/router.go
+++ b/backend/internal/router/router.go
@@ -15,7 +15,7 @@ import (
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
 )

-func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *services.CalDAVService, notifSvc *services.NotificationService, youpcDB ...*sqlx.DB) http.Handler {
+func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *services.CalDAVService, notifSvc *services.NotificationService) http.Handler {
 	mux := http.NewServeMux()

 	// Services
@@ -31,15 +31,14 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	storageCli := services.NewStorageClient(cfg.SupabaseURL, cfg.SupabaseServiceKey)
 	documentSvc := services.NewDocumentService(db, storageCli, auditSvc)
 	assignmentSvc := services.NewCaseAssignmentService(db)
+	timeEntrySvc := services.NewTimeEntryService(db, auditSvc)
+	billingRateSvc := services.NewBillingRateService(db, auditSvc)
+	invoiceSvc := services.NewInvoiceService(db, auditSvc)

 	// AI service (optional — only if API key is configured)
 	var aiH *handlers.AIHandler
 	if cfg.AnthropicAPIKey != "" {
-		var ydb *sqlx.DB
-		if len(youpcDB) > 0 {
-			ydb = youpcDB[0]
-		}
-		aiSvc := services.NewAIService(cfg.AnthropicAPIKey, db, ydb)
+		aiSvc := services.NewAIService(cfg.AnthropicAPIKey, db)
 		aiH = handlers.NewAIHandler(aiSvc)
 	}

@@ -69,6 +68,9 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	eventH := handlers.NewCaseEventHandler(db)
 	docH := handlers.NewDocumentHandler(documentSvc)
 	assignmentH := handlers.NewCaseAssignmentHandler(assignmentSvc)
+	timeEntryH := handlers.NewTimeEntryHandler(timeEntrySvc)
+	billingRateH := handlers.NewBillingRateHandler(billingRateSvc)
+	invoiceH := handlers.NewInvoiceHandler(invoiceSvc)

 	// Public routes
 	mux.HandleFunc("GET /health", handleHealth(db))
@@ -110,7 +112,7 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	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("PUT /api/cases/{id}", caseH.Update)
 	scoped.HandleFunc("DELETE /api/cases/{id}", perm(auth.PermCreateCase, caseH.Delete))

 	// Parties — same access as case editing
@@ -160,24 +162,21 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	// Dashboard — all can view
 	scoped.HandleFunc("GET /api/dashboard", dashboardH.Get)

-	// Audit log
-	scoped.HandleFunc("GET /api/audit-log", auditH.List)
+	// Audit log — view requires PermViewAuditLog
+	scoped.HandleFunc("GET /api/audit-log", perm(auth.PermViewAuditLog, auditH.List))

 	// 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", 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) // permission check inside handler
+	scoped.HandleFunc("DELETE /api/documents/{docId}", docH.Delete)

 	// 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", perm(auth.PermAIExtraction, aiLimiter.LimitFunc(aiH.ExtractDeadlines)))
 		scoped.HandleFunc("POST /api/ai/summarize-case", perm(auth.PermAIExtraction, aiLimiter.LimitFunc(aiH.SummarizeCase)))
-		scoped.HandleFunc("POST /api/ai/draft-document", perm(auth.PermAIExtraction, aiLimiter.LimitFunc(aiH.DraftDocument)))
-		scoped.HandleFunc("POST /api/ai/case-strategy", perm(auth.PermAIExtraction, aiLimiter.LimitFunc(aiH.CaseStrategy)))
-		scoped.HandleFunc("POST /api/ai/similar-cases", perm(auth.PermAIExtraction, aiLimiter.LimitFunc(aiH.SimilarCases)))
 	}

 	// Notifications
@@ -197,6 +196,25 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 		scoped.HandleFunc("GET /api/caldav/status", calDAVH.GetStatus)
 	}

+	// Time entries — billing permission for create/update/delete
+	scoped.HandleFunc("GET /api/cases/{id}/time-entries", timeEntryH.ListForCase)
+	scoped.HandleFunc("POST /api/cases/{id}/time-entries", perm(auth.PermManageBilling, timeEntryH.Create))
+	scoped.HandleFunc("GET /api/time-entries", timeEntryH.List)
+	scoped.HandleFunc("GET /api/time-entries/summary", perm(auth.PermManageBilling, timeEntryH.Summary))
+	scoped.HandleFunc("PUT /api/time-entries/{id}", perm(auth.PermManageBilling, timeEntryH.Update))
+	scoped.HandleFunc("DELETE /api/time-entries/{id}", perm(auth.PermManageBilling, timeEntryH.Delete))
+
+	// Billing rates — billing permission required
+	scoped.HandleFunc("GET /api/billing-rates", perm(auth.PermManageBilling, billingRateH.List))
+	scoped.HandleFunc("PUT /api/billing-rates", perm(auth.PermManageBilling, billingRateH.Upsert))
+
+	// Invoices — billing permission required
+	scoped.HandleFunc("GET /api/invoices", perm(auth.PermManageBilling, invoiceH.List))
+	scoped.HandleFunc("POST /api/invoices", perm(auth.PermManageBilling, invoiceH.Create))
+	scoped.HandleFunc("GET /api/invoices/{id}", perm(auth.PermManageBilling, invoiceH.Get))
+	scoped.HandleFunc("PUT /api/invoices/{id}", perm(auth.PermManageBilling, invoiceH.Update))
+	scoped.HandleFunc("PATCH /api/invoices/{id}/status", perm(auth.PermManageBilling, invoiceH.UpdateStatus))
+
 	// Wire: auth -> tenant routes go directly, scoped routes get tenant resolver
 	api.Handle("/api/", tenantResolver.Resolve(scoped))

--- a/backend/internal/services/ai_service.go
+++ b/backend/internal/services/ai_service.go
@@ -5,7 +5,6 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
-	"strings"
 	"time"

 	"github.com/anthropics/anthropic-sdk-go"
@@ -19,12 +18,11 @@ import (
 type AIService struct {
 	client anthropic.Client
 	db     *sqlx.DB
-	youpcDB *sqlx.DB // read-only connection to youpc.org for similar case finder (may be nil)
 }

-func NewAIService(apiKey string, db *sqlx.DB, youpcDB *sqlx.DB) *AIService {
+func NewAIService(apiKey string, db *sqlx.DB) *AIService {
 	client := anthropic.NewClient(option.WithAPIKey(apiKey))
-	return &AIService{client: client, db: db, youpcDB: youpcDB}
+	return &AIService{client: client, db: db}
 }

 // ExtractedDeadline represents a deadline extracted by AI from a document.
@@ -283,726 +281,3 @@ func (s *AIService) SummarizeCase(ctx context.Context, tenantID, caseID uuid.UUI

 	return summary, nil
 }
-
-// --- Document Drafting ---
-
-// DocumentDraft represents an AI-generated document draft.
-type DocumentDraft struct {
-	Title    string `json:"title"`
-	Content  string `json:"content"`
-	Language string `json:"language"`
-}
-
-// templateDescriptions maps template type IDs to descriptions for Claude.
-var templateDescriptions = map[string]string{
-	"klageschrift":      "Klageschrift (Statement of Claim) — formal complaint initiating legal proceedings",
-	"klageerwiderung":   "Klageerwiderung (Statement of Defence) — formal response to a statement of claim",
-	"abmahnung":         "Abmahnung (Cease and Desist Letter) — formal warning letter demanding cessation of an activity",
-	"schriftsatz":       "Schriftsatz (Legal Brief) — formal legal submission to the court",
-	"berufung":          "Berufungsschrift (Appeal Brief) — formal appeal against a court decision",
-	"antrag":            "Antrag (Motion/Application) — formal application or motion to the court",
-	"stellungnahme":     "Stellungnahme (Statement/Position Paper) — formal response or position paper",
-	"gutachten":         "Gutachten (Legal Opinion/Expert Report) — detailed legal analysis or opinion",
-	"vertrag":           "Vertrag (Contract/Agreement) — legal contract or agreement between parties",
-	"vollmacht":         "Vollmacht (Power of Attorney) — formal authorization document",
-	"upc_claim":         "UPC Statement of Claim — claim filed at the Unified Patent Court",
-	"upc_defence":       "UPC Statement of Defence — defence filed at the Unified Patent Court",
-	"upc_counterclaim":  "UPC Counterclaim for Revocation — counterclaim for patent revocation at the UPC",
-	"upc_injunction":    "UPC Application for Provisional Measures — application for injunctive relief at the UPC",
-}
-
-const draftDocumentSystemPrompt = `You are an expert legal document drafter for German and UPC (Unified Patent Court) patent litigation.
-
-You draft professional legal documents in the requested language, following proper legal formatting conventions.
-
-Guidelines:
- Use proper legal structure with numbered sections and paragraphs
- Include standard legal formalities (headers, salutations, signatures block)
- Reference relevant legal provisions (BGB, ZPO, UPC Rules of Procedure, etc.)
- Use precise legal terminology appropriate for the jurisdiction
- Include placeholders in [BRACKETS] for information that needs to be filled in
- Base the content on the provided case data and instructions
- Output the document as clean text with proper formatting`
-
-// DraftDocument generates an AI-drafted legal document based on case data and a template type.
-func (s *AIService) DraftDocument(ctx context.Context, tenantID, caseID uuid.UUID, templateType, instructions, language string) (*DocumentDraft, error) {
-	if language == "" {
-		language = "de"
-	}
-
-	langLabel := "German"
-	if language == "en" {
-		langLabel = "English"
-	} else if language == "fr" {
-		langLabel = "French"
-	}
-
-	// Load case data
-	var c models.Case
-	if err := s.db.GetContext(ctx, &c,
-		"SELECT * FROM cases WHERE id = $1 AND tenant_id = $2", caseID, tenantID); err != nil {
-		return nil, fmt.Errorf("loading case: %w", err)
-	}
-
-	// Load parties
-	var parties []models.Party
-	_ = s.db.SelectContext(ctx, &parties,
-		"SELECT * FROM parties WHERE case_id = $1 AND tenant_id = $2", caseID, tenantID)
-
-	// Load recent events
-	var events []models.CaseEvent
-	_ = s.db.SelectContext(ctx, &events,
-		"SELECT * FROM case_events WHERE case_id = $1 AND tenant_id = $2 ORDER BY created_at DESC LIMIT 15",
-		caseID, tenantID)
-
-	// Load active deadlines
-	var deadlines []models.Deadline
-	_ = s.db.SelectContext(ctx, &deadlines,
-		"SELECT * FROM deadlines WHERE case_id = $1 AND tenant_id = $2 AND status = 'active' ORDER BY due_date ASC LIMIT 10",
-		caseID, tenantID)
-
-	// Load documents metadata for context
-	var documents []models.Document
-	_ = s.db.SelectContext(ctx, &documents,
-		"SELECT id, title, doc_type, created_at FROM documents WHERE case_id = $1 AND tenant_id = $2 ORDER BY created_at DESC LIMIT 10",
-		caseID, tenantID)
-
-	// Build context
-	var b strings.Builder
-	b.WriteString(fmt.Sprintf("Case: %s — %s\nStatus: %s\n", c.CaseNumber, c.Title, c.Status))
-	if c.Court != nil {
-		b.WriteString(fmt.Sprintf("Court: %s\n", *c.Court))
-	}
-	if c.CourtRef != nil {
-		b.WriteString(fmt.Sprintf("Court Reference: %s\n", *c.CourtRef))
-	}
-	if c.CaseType != nil {
-		b.WriteString(fmt.Sprintf("Type: %s\n", *c.CaseType))
-	}
-
-	if len(parties) > 0 {
-		b.WriteString("\nParties:\n")
-		for _, p := range parties {
-			role := "unknown role"
-			if p.Role != nil {
-				role = *p.Role
-			}
-			b.WriteString(fmt.Sprintf("- %s (%s)", p.Name, role))
-			if p.Representative != nil {
-				b.WriteString(fmt.Sprintf(" — represented by %s", *p.Representative))
-			}
-			b.WriteString("\n")
-		}
-	}
-
-	if len(events) > 0 {
-		b.WriteString("\nRecent Events:\n")
-		for _, e := range events {
-			b.WriteString(fmt.Sprintf("- [%s] %s", e.CreatedAt.Format("2006-01-02"), e.Title))
-			if e.Description != nil {
-				b.WriteString(fmt.Sprintf(": %s", *e.Description))
-			}
-			b.WriteString("\n")
-		}
-	}
-
-	if len(deadlines) > 0 {
-		b.WriteString("\nUpcoming Deadlines:\n")
-		for _, d := range deadlines {
-			b.WriteString(fmt.Sprintf("- %s: due %s\n", d.Title, d.DueDate))
-		}
-	}
-
-	templateDesc, ok := templateDescriptions[templateType]
-	if !ok {
-		templateDesc = templateType
-	}
-
-	prompt := fmt.Sprintf(`Draft a %s for this case in %s.
-
-Document type: %s
-
-Case context:
-%s
-Additional instructions from the lawyer:
-%s
-
-Generate the complete document now.`, templateDesc, langLabel, templateDesc, b.String(), instructions)
-
-	msg, err := s.client.Messages.New(ctx, anthropic.MessageNewParams{
-		Model:     anthropic.ModelClaudeSonnet4_20250514,
-		MaxTokens: 8192,
-		System: []anthropic.TextBlockParam{
-			{Text: draftDocumentSystemPrompt},
-		},
-		Messages: []anthropic.MessageParam{
-			anthropic.NewUserMessage(anthropic.NewTextBlock(prompt)),
-		},
-	})
-	if err != nil {
-		return nil, fmt.Errorf("claude API call: %w", err)
-	}
-
-	var content string
-	for _, block := range msg.Content {
-		if block.Type == "text" {
-			content += block.Text
-		}
-	}
-	if content == "" {
-		return nil, fmt.Errorf("empty response from Claude")
-	}
-
-	title := fmt.Sprintf("%s — %s", templateDesc, c.CaseNumber)
-	return &DocumentDraft{
-		Title:    title,
-		Content:  content,
-		Language: language,
-	}, nil
-}
-
-// --- Case Strategy ---
-
-// StrategyRecommendation represents an AI-generated case strategy analysis.
-type StrategyRecommendation struct {
-	Summary        string           `json:"summary"`
-	NextSteps      []StrategyStep   `json:"next_steps"`
-	RiskAssessment []RiskItem       `json:"risk_assessment"`
-	Timeline       []TimelineItem   `json:"timeline"`
-}
-
-type StrategyStep struct {
-	Priority    string `json:"priority"` // high, medium, low
-	Action      string `json:"action"`
-	Reasoning   string `json:"reasoning"`
-	Deadline    string `json:"deadline,omitempty"`
-}
-
-type RiskItem struct {
-	Level       string `json:"level"` // high, medium, low
-	Risk        string `json:"risk"`
-	Mitigation  string `json:"mitigation"`
-}
-
-type TimelineItem struct {
-	Date        string `json:"date"`
-	Event       string `json:"event"`
-	Importance  string `json:"importance"` // critical, important, routine
-}
-
-type strategyToolInput struct {
-	Summary        string         `json:"summary"`
-	NextSteps      []StrategyStep `json:"next_steps"`
-	RiskAssessment []RiskItem     `json:"risk_assessment"`
-	Timeline       []TimelineItem `json:"timeline"`
-}
-
-var caseStrategyTool = anthropic.ToolParam{
-	Name:        "case_strategy",
-	Description: anthropic.String("Provide strategic case analysis with next steps, risk assessment, and timeline optimization."),
-	InputSchema: anthropic.ToolInputSchemaParam{
-		Properties: map[string]any{
-			"summary": map[string]any{
-				"type":        "string",
-				"description": "Executive summary of the case situation and strategic outlook (2-4 sentences)",
-			},
-			"next_steps": map[string]any{
-				"type":        "array",
-				"description": "Recommended next actions in priority order",
-				"items": map[string]any{
-					"type": "object",
-					"properties": map[string]any{
-						"priority": map[string]any{
-							"type": "string",
-							"enum": []string{"high", "medium", "low"},
-						},
-						"action": map[string]any{
-							"type":        "string",
-							"description": "Specific recommended action",
-						},
-						"reasoning": map[string]any{
-							"type":        "string",
-							"description": "Why this action is recommended",
-						},
-						"deadline": map[string]any{
-							"type":        "string",
-							"description": "Suggested deadline in YYYY-MM-DD format, if applicable",
-						},
-					},
-					"required": []string{"priority", "action", "reasoning"},
-				},
-			},
-			"risk_assessment": map[string]any{
-				"type":        "array",
-				"description": "Key risks and mitigation strategies",
-				"items": map[string]any{
-					"type": "object",
-					"properties": map[string]any{
-						"level": map[string]any{
-							"type": "string",
-							"enum": []string{"high", "medium", "low"},
-						},
-						"risk": map[string]any{
-							"type":        "string",
-							"description": "Description of the risk",
-						},
-						"mitigation": map[string]any{
-							"type":        "string",
-							"description": "Recommended mitigation strategy",
-						},
-					},
-					"required": []string{"level", "risk", "mitigation"},
-				},
-			},
-			"timeline": map[string]any{
-				"type":        "array",
-				"description": "Optimized timeline of upcoming milestones and events",
-				"items": map[string]any{
-					"type": "object",
-					"properties": map[string]any{
-						"date": map[string]any{
-							"type":        "string",
-							"description": "Date in YYYY-MM-DD format",
-						},
-						"event": map[string]any{
-							"type":        "string",
-							"description": "Description of the milestone or event",
-						},
-						"importance": map[string]any{
-							"type": "string",
-							"enum": []string{"critical", "important", "routine"},
-						},
-					},
-					"required": []string{"date", "event", "importance"},
-				},
-			},
-		},
-		Required: []string{"summary", "next_steps", "risk_assessment", "timeline"},
-	},
-}
-
-const caseStrategySystemPrompt = `You are a senior litigation strategist specializing in German law and UPC (Unified Patent Court) patent proceedings.
-
-Analyze the case thoroughly and provide:
-1. An executive summary of the current strategic position
-2. Prioritized next steps with clear reasoning
-3. Risk assessment with mitigation strategies
-4. An optimized timeline of upcoming milestones
-
-Consider:
- Procedural deadlines and their implications
- Strength of the parties' positions based on available information
- Potential settlement opportunities
- Cost-efficiency of different strategic approaches
- UPC-specific procedural peculiarities if applicable (bifurcation, preliminary injunctions, etc.)
-
-Be practical and actionable. Avoid generic advice — tailor recommendations to the specific case data provided.`
-
-// CaseStrategy analyzes a case and returns strategic recommendations.
-func (s *AIService) CaseStrategy(ctx context.Context, tenantID, caseID uuid.UUID) (*StrategyRecommendation, error) {
-	// Load case
-	var c models.Case
-	if err := s.db.GetContext(ctx, &c,
-		"SELECT * FROM cases WHERE id = $1 AND tenant_id = $2", caseID, tenantID); err != nil {
-		return nil, fmt.Errorf("loading case: %w", err)
-	}
-
-	// Load parties
-	var parties []models.Party
-	_ = s.db.SelectContext(ctx, &parties,
-		"SELECT * FROM parties WHERE case_id = $1 AND tenant_id = $2", caseID, tenantID)
-
-	// Load all events
-	var events []models.CaseEvent
-	_ = s.db.SelectContext(ctx, &events,
-		"SELECT * FROM case_events WHERE case_id = $1 AND tenant_id = $2 ORDER BY created_at DESC LIMIT 25",
-		caseID, tenantID)
-
-	// Load all deadlines (active + completed for context)
-	var deadlines []models.Deadline
-	_ = s.db.SelectContext(ctx, &deadlines,
-		"SELECT * FROM deadlines WHERE case_id = $1 AND tenant_id = $2 ORDER BY due_date ASC LIMIT 20",
-		caseID, tenantID)
-
-	// Load documents metadata
-	var documents []models.Document
-	_ = s.db.SelectContext(ctx, &documents,
-		"SELECT id, title, doc_type, created_at FROM documents WHERE case_id = $1 AND tenant_id = $2 ORDER BY created_at DESC LIMIT 15",
-		caseID, tenantID)
-
-	// Build comprehensive context
-	var b strings.Builder
-	b.WriteString(fmt.Sprintf("Case: %s — %s\nStatus: %s\n", c.CaseNumber, c.Title, c.Status))
-	if c.Court != nil {
-		b.WriteString(fmt.Sprintf("Court: %s\n", *c.Court))
-	}
-	if c.CourtRef != nil {
-		b.WriteString(fmt.Sprintf("Court Reference: %s\n", *c.CourtRef))
-	}
-	if c.CaseType != nil {
-		b.WriteString(fmt.Sprintf("Type: %s\n", *c.CaseType))
-	}
-
-	if len(parties) > 0 {
-		b.WriteString("\nParties:\n")
-		for _, p := range parties {
-			role := "unknown"
-			if p.Role != nil {
-				role = *p.Role
-			}
-			b.WriteString(fmt.Sprintf("- %s (%s)", p.Name, role))
-			if p.Representative != nil {
-				b.WriteString(fmt.Sprintf(" — represented by %s", *p.Representative))
-			}
-			b.WriteString("\n")
-		}
-	}
-
-	if len(events) > 0 {
-		b.WriteString("\nCase Events (chronological):\n")
-		for _, e := range events {
-			b.WriteString(fmt.Sprintf("- [%s] %s", e.CreatedAt.Format("2006-01-02"), e.Title))
-			if e.Description != nil {
-				b.WriteString(fmt.Sprintf(": %s", *e.Description))
-			}
-			b.WriteString("\n")
-		}
-	}
-
-	if len(deadlines) > 0 {
-		b.WriteString("\nDeadlines:\n")
-		for _, d := range deadlines {
-			b.WriteString(fmt.Sprintf("- %s: due %s (status: %s)\n", d.Title, d.DueDate, d.Status))
-		}
-	}
-
-	if len(documents) > 0 {
-		b.WriteString("\nDocuments on file:\n")
-		for _, d := range documents {
-			docType := ""
-			if d.DocType != nil {
-				docType = fmt.Sprintf(" [%s]", *d.DocType)
-			}
-			b.WriteString(fmt.Sprintf("- %s%s (%s)\n", d.Title, docType, d.CreatedAt.Format("2006-01-02")))
-		}
-	}
-
-	msg, err := s.client.Messages.New(ctx, anthropic.MessageNewParams{
-		Model:     anthropic.ModelClaudeOpus4_6,
-		MaxTokens: 4096,
-		System: []anthropic.TextBlockParam{
-			{Text: caseStrategySystemPrompt},
-		},
-		Messages: []anthropic.MessageParam{
-			anthropic.NewUserMessage(anthropic.NewTextBlock("Analyze this case and provide strategic recommendations:\n\n" + b.String())),
-		},
-		Tools: []anthropic.ToolUnionParam{
-			{OfTool: &caseStrategyTool},
-		},
-		ToolChoice: anthropic.ToolChoiceParamOfTool("case_strategy"),
-	})
-	if err != nil {
-		return nil, fmt.Errorf("claude API call: %w", err)
-	}
-
-	for _, block := range msg.Content {
-		if block.Type == "tool_use" && block.Name == "case_strategy" {
-			var input strategyToolInput
-			if err := json.Unmarshal(block.Input, &input); err != nil {
-				return nil, fmt.Errorf("parsing strategy output: %w", err)
-			}
-			result := &StrategyRecommendation{
-				Summary:        input.Summary,
-				NextSteps:      input.NextSteps,
-				RiskAssessment: input.RiskAssessment,
-				Timeline:       input.Timeline,
-			}
-			// Cache in database
-			strategyJSON, _ := json.Marshal(result)
-			_, _ = s.db.ExecContext(ctx,
-				"UPDATE cases SET ai_summary = $1, updated_at = $2 WHERE id = $3 AND tenant_id = $4",
-				string(strategyJSON), time.Now(), caseID, tenantID)
-			return result, nil
-		}
-	}
-
-	return nil, fmt.Errorf("no tool_use block in response")
-}
-
-// --- Similar Case Finder ---
-
-// SimilarCase represents a UPC case found to be similar.
-type SimilarCase struct {
-	CaseNumber   string  `json:"case_number"`
-	Title        string  `json:"title"`
-	Court        string  `json:"court"`
-	Date         string  `json:"date"`
-	Relevance    float64 `json:"relevance"`    // 0.0-1.0
-	Explanation  string  `json:"explanation"`   // why this case is similar
-	KeyHoldings  string  `json:"key_holdings"`  // relevant holdings
-	URL          string  `json:"url,omitempty"` // link to youpc.org
-}
-
-// youpcCase represents a case from the youpc.org database.
-type youpcCase struct {
-	ID            string  `db:"id" json:"id"`
-	CaseNumber    *string `db:"case_number" json:"case_number"`
-	Title         *string `db:"title" json:"title"`
-	Court         *string `db:"court" json:"court"`
-	DecisionDate  *string `db:"decision_date" json:"decision_date"`
-	CaseType      *string `db:"case_type" json:"case_type"`
-	Outcome       *string `db:"outcome" json:"outcome"`
-	PatentNumbers *string `db:"patent_numbers" json:"patent_numbers"`
-	Summary       *string `db:"summary" json:"summary"`
-	Claimant      *string `db:"claimant" json:"claimant"`
-	Defendant     *string `db:"defendant" json:"defendant"`
-}
-
-type similarCaseToolInput struct {
-	Cases []struct {
-		CaseID      string  `json:"case_id"`
-		Relevance   float64 `json:"relevance"`
-		Explanation string  `json:"explanation"`
-		KeyHoldings string  `json:"key_holdings"`
-	} `json:"cases"`
-}
-
-var similarCaseTool = anthropic.ToolParam{
-	Name:        "rank_similar_cases",
-	Description: anthropic.String("Rank the provided UPC cases by relevance to the query case and explain why each is similar."),
-	InputSchema: anthropic.ToolInputSchemaParam{
-		Properties: map[string]any{
-			"cases": map[string]any{
-				"type":        "array",
-				"description": "UPC cases ranked by relevance (most relevant first)",
-				"items": map[string]any{
-					"type": "object",
-					"properties": map[string]any{
-						"case_id": map[string]any{
-							"type":        "string",
-							"description": "The ID of the UPC case from the provided list",
-						},
-						"relevance": map[string]any{
-							"type":        "number",
-							"minimum":     0,
-							"maximum":     1,
-							"description": "Relevance score from 0.0 to 1.0",
-						},
-						"explanation": map[string]any{
-							"type":        "string",
-							"description": "Why this case is relevant — what legal issues, parties, patents, or procedural aspects are similar",
-						},
-						"key_holdings": map[string]any{
-							"type":        "string",
-							"description": "Key holdings or legal principles from this case that are relevant",
-						},
-					},
-					"required": []string{"case_id", "relevance", "explanation", "key_holdings"},
-				},
-			},
-		},
-		Required: []string{"cases"},
-	},
-}
-
-const similarCaseSystemPrompt = `You are a UPC (Unified Patent Court) case law expert.
-
-Given a case description and a list of UPC cases from the database, rank the cases by relevance and explain why each one is similar or relevant.
-
-Consider:
- Similar patents or technology areas
- Same parties or representatives
- Similar legal issues (infringement, validity, injunctions, etc.)
- Similar procedural situations
- Relevant legal principles that could apply
-
-Only include cases that are genuinely relevant (relevance > 0.3). Order by relevance descending.`
-
-// FindSimilarCases searches the youpc.org database for similar UPC cases.
-func (s *AIService) FindSimilarCases(ctx context.Context, tenantID, caseID uuid.UUID, description string) ([]SimilarCase, error) {
-	if s.youpcDB == nil {
-		return nil, fmt.Errorf("youpc.org database not configured")
-	}
-
-	// Build query context from the case (if provided) or description
-	var queryText string
-	if caseID != uuid.Nil {
-		var c models.Case
-		if err := s.db.GetContext(ctx, &c,
-			"SELECT * FROM cases WHERE id = $1 AND tenant_id = $2", caseID, tenantID); err != nil {
-			return nil, fmt.Errorf("loading case: %w", err)
-		}
-
-		var parties []models.Party
-		_ = s.db.SelectContext(ctx, &parties,
-			"SELECT * FROM parties WHERE case_id = $1 AND tenant_id = $2", caseID, tenantID)
-
-		var b strings.Builder
-		b.WriteString(fmt.Sprintf("Case: %s — %s\n", c.CaseNumber, c.Title))
-		if c.CaseType != nil {
-			b.WriteString(fmt.Sprintf("Type: %s\n", *c.CaseType))
-		}
-		if c.Court != nil {
-			b.WriteString(fmt.Sprintf("Court: %s\n", *c.Court))
-		}
-		for _, p := range parties {
-			role := ""
-			if p.Role != nil {
-				role = *p.Role
-			}
-			b.WriteString(fmt.Sprintf("Party: %s (%s)\n", p.Name, role))
-		}
-		if description != "" {
-			b.WriteString(fmt.Sprintf("\nAdditional context: %s\n", description))
-		}
-		queryText = b.String()
-	} else if description != "" {
-		queryText = description
-	} else {
-		return nil, fmt.Errorf("either case_id or description must be provided")
-	}
-
-	// Query youpc.org database for candidate cases
-	// Search by text similarity across case titles, summaries, party names
-	var candidates []youpcCase
-	err := s.youpcDB.SelectContext(ctx, &candidates, `
-		SELECT
-			id,
-			case_number,
-			title,
-			court,
-			decision_date,
-			case_type,
-			outcome,
-			patent_numbers,
-			summary,
-			claimant,
-			defendant
-		FROM mlex.cases
-		ORDER BY decision_date DESC NULLS LAST
-		LIMIT 50
-	`)
-	if err != nil {
-		return nil, fmt.Errorf("querying youpc.org cases: %w", err)
-	}
-
-	if len(candidates) == 0 {
-		return []SimilarCase{}, nil
-	}
-
-	// Build candidate list for Claude
-	var candidateText strings.Builder
-	for _, c := range candidates {
-		candidateText.WriteString(fmt.Sprintf("ID: %s\n", c.ID))
-		if c.CaseNumber != nil {
-			candidateText.WriteString(fmt.Sprintf("Case Number: %s\n", *c.CaseNumber))
-		}
-		if c.Title != nil {
-			candidateText.WriteString(fmt.Sprintf("Title: %s\n", *c.Title))
-		}
-		if c.Court != nil {
-			candidateText.WriteString(fmt.Sprintf("Court: %s\n", *c.Court))
-		}
-		if c.DecisionDate != nil {
-			candidateText.WriteString(fmt.Sprintf("Decision Date: %s\n", *c.DecisionDate))
-		}
-		if c.CaseType != nil {
-			candidateText.WriteString(fmt.Sprintf("Type: %s\n", *c.CaseType))
-		}
-		if c.Outcome != nil {
-			candidateText.WriteString(fmt.Sprintf("Outcome: %s\n", *c.Outcome))
-		}
-		if c.PatentNumbers != nil {
-			candidateText.WriteString(fmt.Sprintf("Patents: %s\n", *c.PatentNumbers))
-		}
-		if c.Claimant != nil {
-			candidateText.WriteString(fmt.Sprintf("Claimant: %s\n", *c.Claimant))
-		}
-		if c.Defendant != nil {
-			candidateText.WriteString(fmt.Sprintf("Defendant: %s\n", *c.Defendant))
-		}
-		if c.Summary != nil {
-			candidateText.WriteString(fmt.Sprintf("Summary: %s\n", *c.Summary))
-		}
-		candidateText.WriteString("---\n")
-	}
-
-	prompt := fmt.Sprintf(`Find UPC cases relevant to this matter:
-
-%s
-
-Here are the UPC cases from the database to evaluate:
-
-%s
-
-Rank only the genuinely relevant cases by similarity.`, queryText, candidateText.String())
-
-	msg, err := s.client.Messages.New(ctx, anthropic.MessageNewParams{
-		Model:     anthropic.ModelClaudeSonnet4_20250514,
-		MaxTokens: 4096,
-		System: []anthropic.TextBlockParam{
-			{Text: similarCaseSystemPrompt},
-		},
-		Messages: []anthropic.MessageParam{
-			anthropic.NewUserMessage(anthropic.NewTextBlock(prompt)),
-		},
-		Tools: []anthropic.ToolUnionParam{
-			{OfTool: &similarCaseTool},
-		},
-		ToolChoice: anthropic.ToolChoiceParamOfTool("rank_similar_cases"),
-	})
-	if err != nil {
-		return nil, fmt.Errorf("claude API call: %w", err)
-	}
-
-	for _, block := range msg.Content {
-		if block.Type == "tool_use" && block.Name == "rank_similar_cases" {
-			var input similarCaseToolInput
-			if err := json.Unmarshal(block.Input, &input); err != nil {
-				return nil, fmt.Errorf("parsing similar cases output: %w", err)
-			}
-
-			// Build lookup map for candidate data
-			candidateMap := make(map[string]youpcCase)
-			for _, c := range candidates {
-				candidateMap[c.ID] = c
-			}
-
-			var results []SimilarCase
-			for _, ranked := range input.Cases {
-				if ranked.Relevance < 0.3 {
-					continue
-				}
-				c, ok := candidateMap[ranked.CaseID]
-				if !ok {
-					continue
-				}
-				sc := SimilarCase{
-					Relevance:   ranked.Relevance,
-					Explanation: ranked.Explanation,
-					KeyHoldings: ranked.KeyHoldings,
-				}
-				if c.CaseNumber != nil {
-					sc.CaseNumber = *c.CaseNumber
-				}
-				if c.Title != nil {
-					sc.Title = *c.Title
-				}
-				if c.Court != nil {
-					sc.Court = *c.Court
-				}
-				if c.DecisionDate != nil {
-					sc.Date = *c.DecisionDate
-				}
-				if c.CaseNumber != nil {
-					sc.URL = fmt.Sprintf("https://youpc.org/cases/%s", *c.CaseNumber)
-				}
-				results = append(results, sc)
-			}
-
-			return results, nil
-		}
-	}
-
-	return nil, fmt.Errorf("no tool_use block in response")
-}
--- a/backend/internal/services/billing_rate_service.go
+++ b/backend/internal/services/billing_rate_service.go
@@ -0,0 +1,88 @@
+package services
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/google/uuid"
+	"github.com/jmoiron/sqlx"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/models"
+)
+
+type BillingRateService struct {
+	db    *sqlx.DB
+	audit *AuditService
+}
+
+func NewBillingRateService(db *sqlx.DB, audit *AuditService) *BillingRateService {
+	return &BillingRateService{db: db, audit: audit}
+}
+
+type UpsertBillingRateInput struct {
+	UserID    *uuid.UUID `json:"user_id,omitempty"`
+	Rate      float64    `json:"rate"`
+	Currency  string     `json:"currency"`
+	ValidFrom string     `json:"valid_from"`
+	ValidTo   *string    `json:"valid_to,omitempty"`
+}
+
+func (s *BillingRateService) List(ctx context.Context, tenantID uuid.UUID) ([]models.BillingRate, error) {
+	var rates []models.BillingRate
+	err := s.db.SelectContext(ctx, &rates,
+		`SELECT id, tenant_id, user_id, rate, currency, valid_from, valid_to, created_at
+		 FROM billing_rates
+		 WHERE tenant_id = $1
+		 ORDER BY valid_from DESC, user_id NULLS LAST`,
+		tenantID)
+	if err != nil {
+		return nil, fmt.Errorf("list billing rates: %w", err)
+	}
+	return rates, nil
+}
+
+func (s *BillingRateService) Upsert(ctx context.Context, tenantID uuid.UUID, input UpsertBillingRateInput) (*models.BillingRate, error) {
+	if input.Currency == "" {
+		input.Currency = "EUR"
+	}
+
+	// Close any existing open-ended rate for this user
+	_, err := s.db.ExecContext(ctx,
+		`UPDATE billing_rates SET valid_to = $3
+		 WHERE tenant_id = $1
+		 AND (($2::uuid IS NULL AND user_id IS NULL) OR user_id = $2)
+		 AND valid_to IS NULL
+		 AND valid_from < $3`,
+		tenantID, input.UserID, input.ValidFrom)
+	if err != nil {
+		return nil, fmt.Errorf("close existing rate: %w", err)
+	}
+
+	var rate models.BillingRate
+	err = s.db.QueryRowxContext(ctx,
+		`INSERT INTO billing_rates (tenant_id, user_id, rate, currency, valid_from, valid_to)
+		 VALUES ($1, $2, $3, $4, $5, $6)
+		 RETURNING id, tenant_id, user_id, rate, currency, valid_from, valid_to, created_at`,
+		tenantID, input.UserID, input.Rate, input.Currency, input.ValidFrom, input.ValidTo,
+	).StructScan(&rate)
+	if err != nil {
+		return nil, fmt.Errorf("upsert billing rate: %w", err)
+	}
+
+	s.audit.Log(ctx, "create", "billing_rate", &rate.ID, nil, rate)
+	return &rate, nil
+}
+
+func (s *BillingRateService) GetCurrentRate(ctx context.Context, tenantID uuid.UUID, userID uuid.UUID, date string) (*float64, error) {
+	var rate float64
+	err := s.db.GetContext(ctx, &rate,
+		`SELECT rate FROM billing_rates
+		 WHERE tenant_id = $1 AND (user_id = $2 OR user_id IS NULL)
+		 AND valid_from <= $3 AND (valid_to IS NULL OR valid_to >= $3)
+		 ORDER BY user_id NULLS LAST LIMIT 1`,
+		tenantID, userID, date)
+	if err != nil {
+		return nil, err
+	}
+	return &rate, nil
+}
--- a/backend/internal/services/invoice_service.go
+++ b/backend/internal/services/invoice_service.go
@@ -0,0 +1,292 @@
+package services
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/jmoiron/sqlx"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/models"
+)
+
+type InvoiceService struct {
+	db    *sqlx.DB
+	audit *AuditService
+}
+
+func NewInvoiceService(db *sqlx.DB, audit *AuditService) *InvoiceService {
+	return &InvoiceService{db: db, audit: audit}
+}
+
+type CreateInvoiceInput struct {
+	CaseID        uuid.UUID             `json:"case_id"`
+	ClientName    string                `json:"client_name"`
+	ClientAddress *string               `json:"client_address,omitempty"`
+	Items         []models.InvoiceItem  `json:"items"`
+	TaxRate       *float64              `json:"tax_rate,omitempty"`
+	IssuedAt      *string               `json:"issued_at,omitempty"`
+	DueAt         *string               `json:"due_at,omitempty"`
+	Notes         *string               `json:"notes,omitempty"`
+	TimeEntryIDs  []uuid.UUID           `json:"time_entry_ids,omitempty"`
+}
+
+type UpdateInvoiceInput struct {
+	ClientName    *string               `json:"client_name,omitempty"`
+	ClientAddress *string               `json:"client_address,omitempty"`
+	Items         []models.InvoiceItem  `json:"items,omitempty"`
+	TaxRate       *float64              `json:"tax_rate,omitempty"`
+	IssuedAt      *string               `json:"issued_at,omitempty"`
+	DueAt         *string               `json:"due_at,omitempty"`
+	Notes         *string               `json:"notes,omitempty"`
+}
+
+const invoiceCols = `id, tenant_id, case_id, invoice_number, client_name, client_address,
+	items, subtotal, tax_rate, tax_amount, total, status, issued_at, due_at, paid_at, notes,
+	created_by, created_at, updated_at`
+
+func (s *InvoiceService) List(ctx context.Context, tenantID uuid.UUID, caseID *uuid.UUID, status string) ([]models.Invoice, error) {
+	where := "WHERE tenant_id = $1"
+	args := []any{tenantID}
+	argIdx := 2
+
+	if caseID != nil {
+		where += fmt.Sprintf(" AND case_id = $%d", argIdx)
+		args = append(args, *caseID)
+		argIdx++
+	}
+	if status != "" {
+		where += fmt.Sprintf(" AND status = $%d", argIdx)
+		args = append(args, status)
+		argIdx++
+	}
+
+	var invoices []models.Invoice
+	err := s.db.SelectContext(ctx, &invoices,
+		fmt.Sprintf("SELECT %s FROM invoices %s ORDER BY created_at DESC", invoiceCols, where),
+		args...)
+	if err != nil {
+		return nil, fmt.Errorf("list invoices: %w", err)
+	}
+	return invoices, nil
+}
+
+func (s *InvoiceService) GetByID(ctx context.Context, tenantID, invoiceID uuid.UUID) (*models.Invoice, error) {
+	var inv models.Invoice
+	err := s.db.GetContext(ctx, &inv,
+		`SELECT `+invoiceCols+` FROM invoices WHERE tenant_id = $1 AND id = $2`,
+		tenantID, invoiceID)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, fmt.Errorf("get invoice: %w", err)
+	}
+	return &inv, nil
+}
+
+func (s *InvoiceService) Create(ctx context.Context, tenantID, userID uuid.UUID, input CreateInvoiceInput) (*models.Invoice, error) {
+	tx, err := s.db.BeginTxx(ctx, nil)
+	if err != nil {
+		return nil, fmt.Errorf("begin tx: %w", err)
+	}
+	defer tx.Rollback()
+
+	// Generate invoice number: RE-YYYY-NNN
+	year := time.Now().Year()
+	var seq int
+	err = tx.GetContext(ctx, &seq,
+		`SELECT COUNT(*) + 1 FROM invoices WHERE tenant_id = $1 AND invoice_number LIKE $2`,
+		tenantID, fmt.Sprintf("RE-%d-%%", year))
+	if err != nil {
+		return nil, fmt.Errorf("generate invoice number: %w", err)
+	}
+	invoiceNumber := fmt.Sprintf("RE-%d-%03d", year, seq)
+
+	// Calculate totals
+	taxRate := 19.00
+	if input.TaxRate != nil {
+		taxRate = *input.TaxRate
+	}
+
+	var subtotal float64
+	for _, item := range input.Items {
+		subtotal += item.Amount
+	}
+	taxAmount := subtotal * taxRate / 100
+	total := subtotal + taxAmount
+
+	itemsJSON, err := json.Marshal(input.Items)
+	if err != nil {
+		return nil, fmt.Errorf("marshal items: %w", err)
+	}
+
+	var inv models.Invoice
+	err = tx.QueryRowxContext(ctx,
+		`INSERT INTO invoices (tenant_id, case_id, invoice_number, client_name, client_address,
+			items, subtotal, tax_rate, tax_amount, total, issued_at, due_at, notes, created_by)
+		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14)
+		 RETURNING `+invoiceCols,
+		tenantID, input.CaseID, invoiceNumber, input.ClientName, input.ClientAddress,
+		itemsJSON, subtotal, taxRate, taxAmount, total, input.IssuedAt, input.DueAt, input.Notes, userID,
+	).StructScan(&inv)
+	if err != nil {
+		return nil, fmt.Errorf("create invoice: %w", err)
+	}
+
+	// Mark linked time entries as billed
+	if len(input.TimeEntryIDs) > 0 {
+		query, args, err := sqlx.In(
+			`UPDATE time_entries SET billed = true, invoice_id = ? WHERE tenant_id = ? AND id IN (?)`,
+			inv.ID, tenantID, input.TimeEntryIDs)
+		if err != nil {
+			return nil, fmt.Errorf("build time entry update: %w", err)
+		}
+		query = tx.Rebind(query)
+		_, err = tx.ExecContext(ctx, query, args...)
+		if err != nil {
+			return nil, fmt.Errorf("mark time entries billed: %w", err)
+		}
+	}
+
+	if err := tx.Commit(); err != nil {
+		return nil, fmt.Errorf("commit: %w", err)
+	}
+
+	s.audit.Log(ctx, "create", "invoice", &inv.ID, nil, inv)
+	return &inv, nil
+}
+
+func (s *InvoiceService) Update(ctx context.Context, tenantID, invoiceID uuid.UUID, input UpdateInvoiceInput) (*models.Invoice, error) {
+	old, err := s.GetByID(ctx, tenantID, invoiceID)
+	if err != nil {
+		return nil, err
+	}
+	if old == nil {
+		return nil, fmt.Errorf("invoice not found")
+	}
+	if old.Status != "draft" {
+		return nil, fmt.Errorf("can only update draft invoices")
+	}
+
+	// Recalculate totals if items changed
+	var itemsJSON json.RawMessage
+	var subtotal float64
+	taxRate := old.TaxRate
+
+	if input.Items != nil {
+		for _, item := range input.Items {
+			subtotal += item.Amount
+		}
+		itemsJSON, _ = json.Marshal(input.Items)
+	}
+	if input.TaxRate != nil {
+		taxRate = *input.TaxRate
+	}
+
+	if input.Items != nil {
+		taxAmount := subtotal * taxRate / 100
+		total := subtotal + taxAmount
+
+		var inv models.Invoice
+		err = s.db.QueryRowxContext(ctx,
+			`UPDATE invoices SET
+				client_name = COALESCE($3, client_name),
+				client_address = COALESCE($4, client_address),
+				items = $5,
+				subtotal = $6,
+				tax_rate = $7,
+				tax_amount = $8,
+				total = $9,
+				issued_at = COALESCE($10, issued_at),
+				due_at = COALESCE($11, due_at),
+				notes = COALESCE($12, notes),
+				updated_at = now()
+			 WHERE tenant_id = $1 AND id = $2
+			 RETURNING `+invoiceCols,
+			tenantID, invoiceID, input.ClientName, input.ClientAddress,
+			itemsJSON, subtotal, taxRate, subtotal*taxRate/100, total,
+			input.IssuedAt, input.DueAt, input.Notes,
+		).StructScan(&inv)
+		if err != nil {
+			return nil, fmt.Errorf("update invoice: %w", err)
+		}
+		s.audit.Log(ctx, "update", "invoice", &inv.ID, old, inv)
+		return &inv, nil
+	}
+
+	// Update without changing items
+	var inv models.Invoice
+	err = s.db.QueryRowxContext(ctx,
+		`UPDATE invoices SET
+			client_name = COALESCE($3, client_name),
+			client_address = COALESCE($4, client_address),
+			tax_rate = COALESCE($5, tax_rate),
+			issued_at = COALESCE($6, issued_at),
+			due_at = COALESCE($7, due_at),
+			notes = COALESCE($8, notes),
+			updated_at = now()
+		 WHERE tenant_id = $1 AND id = $2
+		 RETURNING `+invoiceCols,
+		tenantID, invoiceID, input.ClientName, input.ClientAddress,
+		input.TaxRate, input.IssuedAt, input.DueAt, input.Notes,
+	).StructScan(&inv)
+	if err != nil {
+		return nil, fmt.Errorf("update invoice: %w", err)
+	}
+
+	s.audit.Log(ctx, "update", "invoice", &inv.ID, old, inv)
+	return &inv, nil
+}
+
+func (s *InvoiceService) UpdateStatus(ctx context.Context, tenantID, invoiceID uuid.UUID, newStatus string) (*models.Invoice, error) {
+	old, err := s.GetByID(ctx, tenantID, invoiceID)
+	if err != nil {
+		return nil, err
+	}
+	if old == nil {
+		return nil, fmt.Errorf("invoice not found")
+	}
+
+	// Validate transitions
+	validTransitions := map[string][]string{
+		"draft":     {"sent", "cancelled"},
+		"sent":      {"paid", "cancelled"},
+		"paid":      {},
+		"cancelled": {},
+	}
+	allowed := validTransitions[old.Status]
+	valid := false
+	for _, s := range allowed {
+		if s == newStatus {
+			valid = true
+			break
+		}
+	}
+	if !valid {
+		return nil, fmt.Errorf("invalid status transition from %s to %s", old.Status, newStatus)
+	}
+
+	var paidAt *time.Time
+	if newStatus == "paid" {
+		now := time.Now()
+		paidAt = &now
+	}
+
+	var inv models.Invoice
+	err = s.db.QueryRowxContext(ctx,
+		`UPDATE invoices SET status = $3, paid_at = COALESCE($4, paid_at), updated_at = now()
+		 WHERE tenant_id = $1 AND id = $2
+		 RETURNING `+invoiceCols,
+		tenantID, invoiceID, newStatus, paidAt,
+	).StructScan(&inv)
+	if err != nil {
+		return nil, fmt.Errorf("update invoice status: %w", err)
+	}
+
+	s.audit.Log(ctx, "update", "invoice", &inv.ID, old, inv)
+	return &inv, nil
+}
--- a/backend/internal/services/time_entry_service.go
+++ b/backend/internal/services/time_entry_service.go
@@ -0,0 +1,276 @@
+package services
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+
+	"github.com/google/uuid"
+	"github.com/jmoiron/sqlx"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/models"
+)
+
+type TimeEntryService struct {
+	db    *sqlx.DB
+	audit *AuditService
+}
+
+func NewTimeEntryService(db *sqlx.DB, audit *AuditService) *TimeEntryService {
+	return &TimeEntryService{db: db, audit: audit}
+}
+
+type CreateTimeEntryInput struct {
+	CaseID          uuid.UUID `json:"case_id"`
+	Date            string    `json:"date"`
+	DurationMinutes int       `json:"duration_minutes"`
+	Description     string    `json:"description"`
+	Activity        *string   `json:"activity,omitempty"`
+	Billable        *bool     `json:"billable,omitempty"`
+	HourlyRate      *float64  `json:"hourly_rate,omitempty"`
+}
+
+type UpdateTimeEntryInput struct {
+	Date            *string  `json:"date,omitempty"`
+	DurationMinutes *int     `json:"duration_minutes,omitempty"`
+	Description     *string  `json:"description,omitempty"`
+	Activity        *string  `json:"activity,omitempty"`
+	Billable        *bool    `json:"billable,omitempty"`
+	HourlyRate      *float64 `json:"hourly_rate,omitempty"`
+}
+
+type TimeEntryFilter struct {
+	CaseID *uuid.UUID
+	UserID *uuid.UUID
+	From   string
+	To     string
+	Limit  int
+	Offset int
+}
+
+type TimeEntrySummary struct {
+	GroupKey       string  `db:"group_key" json:"group_key"`
+	TotalMinutes   int     `db:"total_minutes" json:"total_minutes"`
+	BillableMinutes int   `db:"billable_minutes" json:"billable_minutes"`
+	TotalAmount    float64 `db:"total_amount" json:"total_amount"`
+	EntryCount     int     `db:"entry_count" json:"entry_count"`
+}
+
+const timeEntryCols = `id, tenant_id, case_id, user_id, date, duration_minutes, description,
+	activity, billable, billed, invoice_id, hourly_rate, created_at, updated_at`
+
+func (s *TimeEntryService) ListForCase(ctx context.Context, tenantID, caseID uuid.UUID) ([]models.TimeEntry, error) {
+	var entries []models.TimeEntry
+	err := s.db.SelectContext(ctx, &entries,
+		`SELECT `+timeEntryCols+` FROM time_entries
+		 WHERE tenant_id = $1 AND case_id = $2
+		 ORDER BY date DESC, created_at DESC`,
+		tenantID, caseID)
+	if err != nil {
+		return nil, fmt.Errorf("list time entries for case: %w", err)
+	}
+	return entries, nil
+}
+
+func (s *TimeEntryService) List(ctx context.Context, tenantID uuid.UUID, filter TimeEntryFilter) ([]models.TimeEntry, int, error) {
+	if filter.Limit <= 0 {
+		filter.Limit = 20
+	}
+	if filter.Limit > 100 {
+		filter.Limit = 100
+	}
+
+	where := "WHERE tenant_id = $1"
+	args := []any{tenantID}
+	argIdx := 2
+
+	if filter.CaseID != nil {
+		where += fmt.Sprintf(" AND case_id = $%d", argIdx)
+		args = append(args, *filter.CaseID)
+		argIdx++
+	}
+	if filter.UserID != nil {
+		where += fmt.Sprintf(" AND user_id = $%d", argIdx)
+		args = append(args, *filter.UserID)
+		argIdx++
+	}
+	if filter.From != "" {
+		where += fmt.Sprintf(" AND date >= $%d", argIdx)
+		args = append(args, filter.From)
+		argIdx++
+	}
+	if filter.To != "" {
+		where += fmt.Sprintf(" AND date <= $%d", argIdx)
+		args = append(args, filter.To)
+		argIdx++
+	}
+
+	var total int
+	err := s.db.GetContext(ctx, &total,
+		"SELECT COUNT(*) FROM time_entries "+where, args...)
+	if err != nil {
+		return nil, 0, fmt.Errorf("count time entries: %w", err)
+	}
+
+	query := fmt.Sprintf("SELECT %s FROM time_entries %s ORDER BY date DESC, created_at DESC LIMIT $%d OFFSET $%d",
+		timeEntryCols, where, argIdx, argIdx+1)
+	args = append(args, filter.Limit, filter.Offset)
+
+	var entries []models.TimeEntry
+	err = s.db.SelectContext(ctx, &entries, query, args...)
+	if err != nil {
+		return nil, 0, fmt.Errorf("list time entries: %w", err)
+	}
+	return entries, total, nil
+}
+
+func (s *TimeEntryService) GetByID(ctx context.Context, tenantID, entryID uuid.UUID) (*models.TimeEntry, error) {
+	var entry models.TimeEntry
+	err := s.db.GetContext(ctx, &entry,
+		`SELECT `+timeEntryCols+` FROM time_entries WHERE tenant_id = $1 AND id = $2`,
+		tenantID, entryID)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, fmt.Errorf("get time entry: %w", err)
+	}
+	return &entry, nil
+}
+
+func (s *TimeEntryService) Create(ctx context.Context, tenantID, userID uuid.UUID, input CreateTimeEntryInput) (*models.TimeEntry, error) {
+	billable := true
+	if input.Billable != nil {
+		billable = *input.Billable
+	}
+
+	// If no hourly rate provided, look up the current billing rate
+	hourlyRate := input.HourlyRate
+	if hourlyRate == nil {
+		var rate float64
+		err := s.db.GetContext(ctx, &rate,
+			`SELECT rate FROM billing_rates
+			 WHERE tenant_id = $1 AND (user_id = $2 OR user_id IS NULL)
+			 AND valid_from <= $3 AND (valid_to IS NULL OR valid_to >= $3)
+			 ORDER BY user_id NULLS LAST LIMIT 1`,
+			tenantID, userID, input.Date)
+		if err == nil {
+			hourlyRate = &rate
+		}
+	}
+
+	var entry models.TimeEntry
+	err := s.db.QueryRowxContext(ctx,
+		`INSERT INTO time_entries (tenant_id, case_id, user_id, date, duration_minutes, description, activity, billable, hourly_rate)
+		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
+		 RETURNING `+timeEntryCols,
+		tenantID, input.CaseID, userID, input.Date, input.DurationMinutes, input.Description, input.Activity, billable, hourlyRate,
+	).StructScan(&entry)
+	if err != nil {
+		return nil, fmt.Errorf("create time entry: %w", err)
+	}
+
+	s.audit.Log(ctx, "create", "time_entry", &entry.ID, nil, entry)
+	return &entry, nil
+}
+
+func (s *TimeEntryService) Update(ctx context.Context, tenantID, entryID uuid.UUID, input UpdateTimeEntryInput) (*models.TimeEntry, error) {
+	old, err := s.GetByID(ctx, tenantID, entryID)
+	if err != nil {
+		return nil, err
+	}
+	if old == nil {
+		return nil, fmt.Errorf("time entry not found")
+	}
+	if old.Billed {
+		return nil, fmt.Errorf("cannot update a billed time entry")
+	}
+
+	var entry models.TimeEntry
+	err = s.db.QueryRowxContext(ctx,
+		`UPDATE time_entries SET
+			date = COALESCE($3, date),
+			duration_minutes = COALESCE($4, duration_minutes),
+			description = COALESCE($5, description),
+			activity = COALESCE($6, activity),
+			billable = COALESCE($7, billable),
+			hourly_rate = COALESCE($8, hourly_rate),
+			updated_at = now()
+		 WHERE tenant_id = $1 AND id = $2
+		 RETURNING `+timeEntryCols,
+		tenantID, entryID, input.Date, input.DurationMinutes, input.Description, input.Activity, input.Billable, input.HourlyRate,
+	).StructScan(&entry)
+	if err != nil {
+		return nil, fmt.Errorf("update time entry: %w", err)
+	}
+
+	s.audit.Log(ctx, "update", "time_entry", &entry.ID, old, entry)
+	return &entry, nil
+}
+
+func (s *TimeEntryService) Delete(ctx context.Context, tenantID, entryID uuid.UUID) error {
+	old, err := s.GetByID(ctx, tenantID, entryID)
+	if err != nil {
+		return err
+	}
+	if old == nil {
+		return fmt.Errorf("time entry not found")
+	}
+	if old.Billed {
+		return fmt.Errorf("cannot delete a billed time entry")
+	}
+
+	_, err = s.db.ExecContext(ctx,
+		`DELETE FROM time_entries WHERE tenant_id = $1 AND id = $2`,
+		tenantID, entryID)
+	if err != nil {
+		return fmt.Errorf("delete time entry: %w", err)
+	}
+
+	s.audit.Log(ctx, "delete", "time_entry", &entryID, old, nil)
+	return nil
+}
+
+func (s *TimeEntryService) Summary(ctx context.Context, tenantID uuid.UUID, groupBy string, from, to string) ([]TimeEntrySummary, error) {
+	var groupExpr string
+	switch groupBy {
+	case "user":
+		groupExpr = "user_id::text"
+	case "month":
+		groupExpr = "to_char(date, 'YYYY-MM')"
+	default:
+		groupExpr = "case_id::text"
+	}
+
+	where := "WHERE tenant_id = $1"
+	args := []any{tenantID}
+	argIdx := 2
+
+	if from != "" {
+		where += fmt.Sprintf(" AND date >= $%d", argIdx)
+		args = append(args, from)
+		argIdx++
+	}
+	if to != "" {
+		where += fmt.Sprintf(" AND date <= $%d", argIdx)
+		args = append(args, to)
+		argIdx++
+	}
+
+	query := fmt.Sprintf(`SELECT %s AS group_key,
+		SUM(duration_minutes) AS total_minutes,
+		SUM(CASE WHEN billable THEN duration_minutes ELSE 0 END) AS billable_minutes,
+		SUM(CASE WHEN billable AND hourly_rate IS NOT NULL THEN duration_minutes * hourly_rate / 60.0 ELSE 0 END) AS total_amount,
+		COUNT(*) AS entry_count
+		FROM time_entries %s
+		GROUP BY %s
+		ORDER BY %s`,
+		groupExpr, where, groupExpr, groupExpr)
+
+	var summaries []TimeEntrySummary
+	err := s.db.SelectContext(ctx, &summaries, query, args...)
+	if err != nil {
+		return nil, fmt.Errorf("time entry summary: %w", err)
+	}
+	return summaries, nil
+}
--- a/frontend/src/app/(app)/abrechnung/page.tsx
+++ b/frontend/src/app/(app)/abrechnung/page.tsx
@@ -0,0 +1,164 @@
+"use client";
+
+import { useQuery } from "@tanstack/react-query";
+import { api } from "@/lib/api";
+import type { TimeEntry } from "@/lib/types";
+import { format } from "date-fns";
+import { de } from "date-fns/locale";
+import { Timer, Loader2 } from "lucide-react";
+import { useState } from "react";
+import Link from "next/link";
+import { Breadcrumb } from "@/components/layout/Breadcrumb";
+
+function formatDuration(minutes: number): string {
+  const h = Math.floor(minutes / 60);
+  const m = minutes % 60;
+  if (h === 0) return `${m}min`;
+  if (m === 0) return `${h}h`;
+  return `${h}h ${m}min`;
+}
+
+export default function AbrechnungPage() {
+  const [from, setFrom] = useState(() => {
+    const d = new Date();
+    d.setDate(1);
+    return format(d, "yyyy-MM-dd");
+  });
+  const [to, setTo] = useState(() => format(new Date(), "yyyy-MM-dd"));
+
+  const { data, isLoading } = useQuery({
+    queryKey: ["time-entries", from, to],
+    queryFn: () =>
+      api.get<{ time_entries: TimeEntry[]; total: number }>(
+        `/time-entries?from=${from}&to=${to}&limit=100`,
+      ),
+  });
+
+  const entries = data?.time_entries ?? [];
+  const totalMinutes = entries.reduce((s, e) => s + e.duration_minutes, 0);
+  const billableMinutes = entries
+    .filter((e) => e.billable)
+    .reduce((s, e) => s + e.duration_minutes, 0);
+  const totalAmount = entries
+    .filter((e) => e.billable && e.hourly_rate)
+    .reduce((s, e) => s + (e.duration_minutes / 60) * (e.hourly_rate ?? 0), 0);
+
+  return (
+    <div className="animate-fade-in">
+      <Breadcrumb
+        items={[
+          { label: "Dashboard", href: "/dashboard" },
+          { label: "Abrechnung" },
+        ]}
+      />
+
+      <div className="mt-4 flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+        <h1 className="text-lg font-semibold text-neutral-900">
+          Zeiterfassung
+        </h1>
+        <Link
+          href="/abrechnung/rechnungen"
+          className="text-sm text-neutral-500 transition-colors hover:text-neutral-700"
+        >
+          Rechnungen ansehen &rarr;
+        </Link>
+      </div>
+
+      {/* Filters */}
+      <div className="mt-4 flex flex-wrap items-center gap-3">
+        <div className="flex items-center gap-2">
+          <label className="text-xs text-neutral-500">Von</label>
+          <input
+            type="date"
+            value={from}
+            onChange={(e) => setFrom(e.target.value)}
+            className="rounded-md border border-neutral-300 px-2 py-1 text-sm focus:border-neutral-500 focus:outline-none"
+          />
+        </div>
+        <div className="flex items-center gap-2">
+          <label className="text-xs text-neutral-500">Bis</label>
+          <input
+            type="date"
+            value={to}
+            onChange={(e) => setTo(e.target.value)}
+            className="rounded-md border border-neutral-300 px-2 py-1 text-sm focus:border-neutral-500 focus:outline-none"
+          />
+        </div>
+      </div>
+
+      {/* Summary cards */}
+      <div className="mt-4 grid grid-cols-1 gap-3 sm:grid-cols-3">
+        <div className="rounded-md border border-neutral-200 bg-white p-4">
+          <p className="text-xs text-neutral-500">Gesamt</p>
+          <p className="mt-1 text-xl font-semibold text-neutral-900">
+            {formatDuration(totalMinutes)}
+          </p>
+        </div>
+        <div className="rounded-md border border-neutral-200 bg-white p-4">
+          <p className="text-xs text-neutral-500">Abrechenbar</p>
+          <p className="mt-1 text-xl font-semibold text-neutral-900">
+            {formatDuration(billableMinutes)}
+          </p>
+        </div>
+        <div className="rounded-md border border-neutral-200 bg-white p-4">
+          <p className="text-xs text-neutral-500">Betrag</p>
+          <p className="mt-1 text-xl font-semibold text-neutral-900">
+            {totalAmount.toFixed(2)} EUR
+          </p>
+        </div>
+      </div>
+
+      {/* Entries */}
+      {isLoading ? (
+        <div className="flex items-center justify-center py-8">
+          <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+        </div>
+      ) : entries.length === 0 ? (
+        <div className="flex flex-col items-center py-12 text-center">
+          <div className="rounded-xl bg-neutral-100 p-3">
+            <Timer className="h-5 w-5 text-neutral-400" />
+          </div>
+          <p className="mt-2 text-sm text-neutral-500">
+            Keine Zeiteintraege im gewaehlten Zeitraum.
+          </p>
+        </div>
+      ) : (
+        <div className="mt-4 space-y-2">
+          {entries.map((entry) => (
+            <div
+              key={entry.id}
+              className="flex items-center justify-between rounded-md border border-neutral-200 bg-white px-4 py-3"
+            >
+              <div className="min-w-0 flex-1">
+                <p className="text-sm font-medium text-neutral-900 truncate">
+                  {entry.description}
+                </p>
+                <div className="mt-0.5 flex gap-3 text-xs text-neutral-500">
+                  <span>
+                    {format(new Date(entry.date), "d. MMM yyyy", { locale: de })}
+                  </span>
+                  <Link
+                    href={`/cases/${entry.case_id}/zeiterfassung`}
+                    className="hover:text-neutral-700"
+                  >
+                    Akte ansehen
+                  </Link>
+                </div>
+              </div>
+              <div className="flex items-center gap-4 ml-4 text-sm">
+                {entry.billable ? (
+                  <span className="text-emerald-600">abrechenbar</span>
+                ) : (
+                  <span className="text-neutral-400">intern</span>
+                )}
+                <span className="font-medium text-neutral-900 whitespace-nowrap">
+                  {formatDuration(entry.duration_minutes)}
+                </span>
+              </div>
+            </div>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}
--- a/frontend/src/app/(app)/abrechnung/rechnungen/[id]/page.tsx
+++ b/frontend/src/app/(app)/abrechnung/rechnungen/[id]/page.tsx
@@ -0,0 +1,225 @@
+"use client";
+
+import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
+import { useParams } from "next/navigation";
+import { api } from "@/lib/api";
+import type { Invoice } from "@/lib/types";
+import { format } from "date-fns";
+import { de } from "date-fns/locale";
+import { Loader2, AlertTriangle } from "lucide-react";
+import { Breadcrumb } from "@/components/layout/Breadcrumb";
+
+const STATUS_BADGE: Record<string, string> = {
+  draft: "bg-neutral-100 text-neutral-600",
+  sent: "bg-blue-50 text-blue-700",
+  paid: "bg-emerald-50 text-emerald-700",
+  cancelled: "bg-red-50 text-red-600",
+};
+
+const STATUS_LABEL: Record<string, string> = {
+  draft: "Entwurf",
+  sent: "Versendet",
+  paid: "Bezahlt",
+  cancelled: "Storniert",
+};
+
+const TRANSITIONS: Record<string, { label: string; next: string }[]> = {
+  draft: [
+    { label: "Als versendet markieren", next: "sent" },
+    { label: "Stornieren", next: "cancelled" },
+  ],
+  sent: [
+    { label: "Als bezahlt markieren", next: "paid" },
+    { label: "Stornieren", next: "cancelled" },
+  ],
+  paid: [],
+  cancelled: [],
+};
+
+export default function InvoiceDetailPage() {
+  const { id } = useParams<{ id: string }>();
+  const queryClient = useQueryClient();
+
+  const { data: invoice, isLoading, error } = useQuery({
+    queryKey: ["invoice", id],
+    queryFn: () => api.get<Invoice>(`/invoices/${id}`),
+  });
+
+  const statusMutation = useMutation({
+    mutationFn: (status: string) =>
+      api.patch<Invoice>(`/invoices/${id}/status`, { status }),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["invoice", id] });
+      queryClient.invalidateQueries({ queryKey: ["invoices"] });
+    },
+  });
+
+  if (isLoading) {
+    return (
+      <div className="flex items-center justify-center py-12">
+        <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+      </div>
+    );
+  }
+
+  if (error || !invoice) {
+    return (
+      <div className="py-12 text-center">
+        <AlertTriangle className="mx-auto h-6 w-6 text-red-500" />
+        <p className="mt-2 text-sm text-neutral-500">
+          Rechnung nicht gefunden.
+        </p>
+      </div>
+    );
+  }
+
+  const items = Array.isArray(invoice.items) ? invoice.items : [];
+  const actions = TRANSITIONS[invoice.status] ?? [];
+
+  return (
+    <div className="animate-fade-in">
+      <Breadcrumb
+        items={[
+          { label: "Dashboard", href: "/dashboard" },
+          { label: "Abrechnung", href: "/abrechnung" },
+          { label: "Rechnungen", href: "/abrechnung/rechnungen" },
+          { label: invoice.invoice_number },
+        ]}
+      />
+
+      <div className="mt-4 flex flex-col gap-3 sm:flex-row sm:items-start sm:justify-between">
+        <div>
+          <div className="flex items-center gap-3">
+            <h1 className="text-lg font-semibold text-neutral-900">
+              {invoice.invoice_number}
+            </h1>
+            <span
+              className={`rounded-full px-2 py-0.5 text-xs font-medium ${STATUS_BADGE[invoice.status]}`}
+            >
+              {STATUS_LABEL[invoice.status]}
+            </span>
+          </div>
+          <p className="mt-1 text-sm text-neutral-500">
+            {invoice.client_name}
+          </p>
+        </div>
+        <div className="flex gap-2">
+          {actions.map((action) => (
+            <button
+              key={action.next}
+              onClick={() => statusMutation.mutate(action.next)}
+              disabled={statusMutation.isPending}
+              className="rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800 disabled:opacity-50"
+            >
+              {action.label}
+            </button>
+          ))}
+        </div>
+      </div>
+
+      {/* Invoice details */}
+      <div className="mt-6 rounded-md border border-neutral-200 bg-white">
+        {/* Client info */}
+        <div className="border-b border-neutral-100 p-4">
+          <p className="text-xs text-neutral-500">Empfaenger</p>
+          <p className="mt-1 text-sm font-medium text-neutral-900">
+            {invoice.client_name}
+          </p>
+          {invoice.client_address && (
+            <p className="mt-0.5 text-sm text-neutral-500 whitespace-pre-line">
+              {invoice.client_address}
+            </p>
+          )}
+        </div>
+
+        {/* Dates */}
+        <div className="flex flex-wrap gap-6 border-b border-neutral-100 p-4">
+          {invoice.issued_at && (
+            <div>
+              <p className="text-xs text-neutral-500">Rechnungsdatum</p>
+              <p className="mt-0.5 text-sm text-neutral-900">
+                {format(new Date(invoice.issued_at), "d. MMMM yyyy", { locale: de })}
+              </p>
+            </div>
+          )}
+          {invoice.due_at && (
+            <div>
+              <p className="text-xs text-neutral-500">Faellig am</p>
+              <p className="mt-0.5 text-sm text-neutral-900">
+                {format(new Date(invoice.due_at), "d. MMMM yyyy", { locale: de })}
+              </p>
+            </div>
+          )}
+          {invoice.paid_at && (
+            <div>
+              <p className="text-xs text-neutral-500">Bezahlt am</p>
+              <p className="mt-0.5 text-sm text-neutral-900">
+                {format(new Date(invoice.paid_at), "d. MMMM yyyy", { locale: de })}
+              </p>
+            </div>
+          )}
+        </div>
+
+        {/* Line items */}
+        <div className="p-4">
+          <table className="w-full text-sm">
+            <thead>
+              <tr className="border-b border-neutral-100 text-left text-xs text-neutral-500">
+                <th className="pb-2 font-medium">Beschreibung</th>
+                <th className="pb-2 font-medium text-right">Betrag</th>
+              </tr>
+            </thead>
+            <tbody>
+              {items.map((item, i) => (
+                <tr key={i} className="border-b border-neutral-50">
+                  <td className="py-2 text-neutral-900">
+                    {item.description}
+                    {item.duration_minutes && item.hourly_rate && (
+                      <span className="ml-2 text-xs text-neutral-400">
+                        ({Math.floor(item.duration_minutes / 60)}h{" "}
+                        {item.duration_minutes % 60}min x {item.hourly_rate} EUR/h)
+                      </span>
+                    )}
+                  </td>
+                  <td className="py-2 text-right text-neutral-900">
+                    {item.amount.toFixed(2)} EUR
+                  </td>
+                </tr>
+              ))}
+            </tbody>
+          </table>
+        </div>
+
+        {/* Totals */}
+        <div className="border-t border-neutral-200 p-4">
+          <div className="flex justify-end">
+            <div className="w-48 space-y-1">
+              <div className="flex justify-between text-sm">
+                <span className="text-neutral-500">Netto</span>
+                <span>{invoice.subtotal.toFixed(2)} EUR</span>
+              </div>
+              <div className="flex justify-between text-sm">
+                <span className="text-neutral-500">
+                  USt. {invoice.tax_rate}%
+                </span>
+                <span>{invoice.tax_amount.toFixed(2)} EUR</span>
+              </div>
+              <div className="flex justify-between border-t border-neutral-200 pt-1 text-sm font-semibold">
+                <span>Gesamt</span>
+                <span>{invoice.total.toFixed(2)} EUR</span>
+              </div>
+            </div>
+          </div>
+        </div>
+
+        {/* Notes */}
+        {invoice.notes && (
+          <div className="border-t border-neutral-100 p-4">
+            <p className="text-xs text-neutral-500">Anmerkungen</p>
+            <p className="mt-1 text-sm text-neutral-700">{invoice.notes}</p>
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}
--- a/frontend/src/app/(app)/abrechnung/rechnungen/page.tsx
+++ b/frontend/src/app/(app)/abrechnung/rechnungen/page.tsx
@@ -0,0 +1,118 @@
+"use client";
+
+import { useQuery } from "@tanstack/react-query";
+import { api } from "@/lib/api";
+import type { Invoice } from "@/lib/types";
+import { format } from "date-fns";
+import { de } from "date-fns/locale";
+import { Receipt, Loader2 } from "lucide-react";
+import Link from "next/link";
+import { useState } from "react";
+import { Breadcrumb } from "@/components/layout/Breadcrumb";
+
+const STATUS_BADGE: Record<string, string> = {
+  draft: "bg-neutral-100 text-neutral-600",
+  sent: "bg-blue-50 text-blue-700",
+  paid: "bg-emerald-50 text-emerald-700",
+  cancelled: "bg-red-50 text-red-600",
+};
+
+const STATUS_LABEL: Record<string, string> = {
+  draft: "Entwurf",
+  sent: "Versendet",
+  paid: "Bezahlt",
+  cancelled: "Storniert",
+};
+
+export default function RechnungenPage() {
+  const [statusFilter, setStatusFilter] = useState("");
+
+  const { data, isLoading } = useQuery({
+    queryKey: ["invoices", statusFilter],
+    queryFn: () => {
+      const params = statusFilter ? `?status=${statusFilter}` : "";
+      return api.get<{ invoices: Invoice[] }>(`/invoices${params}`);
+    },
+  });
+
+  const invoices = data?.invoices ?? [];
+
+  return (
+    <div className="animate-fade-in">
+      <Breadcrumb
+        items={[
+          { label: "Dashboard", href: "/dashboard" },
+          { label: "Abrechnung", href: "/abrechnung" },
+          { label: "Rechnungen" },
+        ]}
+      />
+
+      <div className="mt-4 flex items-center justify-between">
+        <h1 className="text-lg font-semibold text-neutral-900">Rechnungen</h1>
+      </div>
+
+      {/* Filters */}
+      <div className="mt-4 flex gap-2">
+        {["", "draft", "sent", "paid", "cancelled"].map((s) => (
+          <button
+            key={s}
+            onClick={() => setStatusFilter(s)}
+            className={`rounded-md px-2.5 py-1 text-xs font-medium transition-colors ${
+              statusFilter === s
+                ? "bg-neutral-900 text-white"
+                : "bg-neutral-100 text-neutral-600 hover:bg-neutral-200"
+            }`}
+          >
+            {s === "" ? "Alle" : STATUS_LABEL[s]}
+          </button>
+        ))}
+      </div>
+
+      {isLoading ? (
+        <div className="flex items-center justify-center py-8">
+          <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+        </div>
+      ) : invoices.length === 0 ? (
+        <div className="flex flex-col items-center py-12 text-center">
+          <div className="rounded-xl bg-neutral-100 p-3">
+            <Receipt className="h-5 w-5 text-neutral-400" />
+          </div>
+          <p className="mt-2 text-sm text-neutral-500">
+            Keine Rechnungen vorhanden.
+          </p>
+        </div>
+      ) : (
+        <div className="mt-4 space-y-2">
+          {invoices.map((inv) => (
+            <Link
+              key={inv.id}
+              href={`/abrechnung/rechnungen/${inv.id}`}
+              className="flex items-center justify-between rounded-md border border-neutral-200 bg-white px-4 py-3 transition-colors hover:bg-neutral-50"
+            >
+              <div>
+                <div className="flex items-center gap-2">
+                  <p className="text-sm font-medium text-neutral-900">
+                    {inv.invoice_number}
+                  </p>
+                  <span
+                    className={`rounded-full px-2 py-0.5 text-xs font-medium ${STATUS_BADGE[inv.status]}`}
+                  >
+                    {STATUS_LABEL[inv.status]}
+                  </span>
+                </div>
+                <p className="mt-0.5 text-xs text-neutral-500">
+                  {inv.client_name}
+                  {inv.issued_at &&
+                    ` — ${format(new Date(inv.issued_at), "d. MMM yyyy", { locale: de })}`}
+                </p>
+              </div>
+              <p className="text-sm font-semibold text-neutral-900">
+                {inv.total.toFixed(2)} EUR
+              </p>
+            </Link>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}
--- a/frontend/src/app/(app)/cases/[id]/ki/page.tsx
+++ b/frontend/src/app/(app)/cases/[id]/ki/page.tsx
@@ -1,51 +0,0 @@
-"use client";
-
-import { useState } from "react";
-import { useParams } from "next/navigation";
-import { Brain, FileText, Search } from "lucide-react";
-import { CaseStrategy } from "@/components/ai/CaseStrategy";
-import { DocumentDrafter } from "@/components/ai/DocumentDrafter";
-import { SimilarCaseFinder } from "@/components/ai/SimilarCaseFinder";
-
-type AITab = "strategy" | "draft" | "similar";
-
-const TABS: { id: AITab; label: string; icon: typeof Brain }[] = [
-  { id: "strategy", label: "KI-Strategie", icon: Brain },
-  { id: "draft", label: "KI-Entwurf", icon: FileText },
-  { id: "similar", label: "Aehnliche Faelle", icon: Search },
-];
-
-export default function CaseAIPage() {
-  const { id } = useParams<{ id: string }>();
-  const [activeTab, setActiveTab] = useState<AITab>("strategy");
-
-  return (
-    <div>
-      {/* Sub-tabs */}
-      <div className="mb-6 flex gap-1 rounded-lg border border-neutral-200 bg-neutral-50 p-1">
-        {TABS.map((tab) => {
-          const isActive = activeTab === tab.id;
-          return (
-            <button
-              key={tab.id}
-              onClick={() => setActiveTab(tab.id)}
-              className={`inline-flex flex-1 items-center justify-center gap-1.5 rounded-md px-3 py-2 text-sm font-medium transition-colors ${
-                isActive
-                  ? "bg-white text-neutral-900 shadow-sm"
-                  : "text-neutral-500 hover:text-neutral-700"
-              }`}
-            >
-              <tab.icon className="h-4 w-4" />
-              {tab.label}
-            </button>
-          );
-        })}
-      </div>
-
-      {/* Content */}
-      {activeTab === "strategy" && <CaseStrategy caseId={id} />}
-      {activeTab === "draft" && <DocumentDrafter caseId={id} />}
-      {activeTab === "similar" && <SimilarCaseFinder caseId={id} />}
-    </div>
-  );
-}
--- a/frontend/src/app/(app)/cases/[id]/layout.tsx
+++ b/frontend/src/app/(app)/cases/[id]/layout.tsx
@@ -17,7 +17,7 @@ import {
  StickyNote,
  AlertTriangle,
  ScrollText,
-  Brain,
+  Timer,
 } from "lucide-react";
 import { format } from "date-fns";
 import { de } from "date-fns/locale";
@@ -47,9 +47,9 @@ const TABS = [
  { segment: "dokumente", label: "Dokumente", icon: FileText },
  { segment: "parteien", label: "Parteien", icon: Users },
  { segment: "mitarbeiter", label: "Mitarbeiter", icon: UserCheck },
+  { segment: "zeiterfassung", label: "Zeiterfassung", icon: Timer },
  { segment: "notizen", label: "Notizen", icon: StickyNote },
  { segment: "protokoll", label: "Protokoll", icon: ScrollText },
-  { segment: "ki", label: "KI", icon: Brain },
 ] as const;

 const TAB_LABELS: Record<string, string> = {
@@ -58,9 +58,9 @@ const TAB_LABELS: Record<string, string> = {
  dokumente: "Dokumente",
  parteien: "Parteien",
  mitarbeiter: "Mitarbeiter",
+  zeiterfassung: "Zeiterfassung",
  notizen: "Notizen",
  protokoll: "Protokoll",
-  ki: "KI",
 };

 function CaseDetailSkeleton() {
--- a/frontend/src/app/(app)/cases/[id]/zeiterfassung/page.tsx
+++ b/frontend/src/app/(app)/cases/[id]/zeiterfassung/page.tsx
@@ -0,0 +1,306 @@
+"use client";
+
+import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
+import { useParams } from "next/navigation";
+import { api } from "@/lib/api";
+import type { TimeEntry } from "@/lib/types";
+import { format } from "date-fns";
+import { de } from "date-fns/locale";
+import { Timer, Loader2, Plus, Trash2 } from "lucide-react";
+import { useState } from "react";
+
+function formatDuration(minutes: number): string {
+  const h = Math.floor(minutes / 60);
+  const m = minutes % 60;
+  if (h === 0) return `${m}min`;
+  if (m === 0) return `${h}h`;
+  return `${h}h ${m}min`;
+}
+
+function formatAmount(minutes: number, rate?: number): string {
+  if (!rate) return "-";
+  return `${((minutes / 60) * rate).toFixed(2)} EUR`;
+}
+
+const ACTIVITIES = [
+  { value: "", label: "Keine Kategorie" },
+  { value: "research", label: "Recherche" },
+  { value: "drafting", label: "Entwurf" },
+  { value: "hearing", label: "Verhandlung" },
+  { value: "call", label: "Telefonat" },
+  { value: "review", label: "Prüfung" },
+  { value: "travel", label: "Reise" },
+  { value: "meeting", label: "Besprechung" },
+];
+
+export default function ZeiterfassungPage() {
+  const { id } = useParams<{ id: string }>();
+  const queryClient = useQueryClient();
+  const [showForm, setShowForm] = useState(false);
+  const [desc, setDesc] = useState("");
+  const [hours, setHours] = useState("");
+  const [minutes, setMinutes] = useState("");
+  const [date, setDate] = useState(format(new Date(), "yyyy-MM-dd"));
+  const [activity, setActivity] = useState("");
+  const [billable, setBillable] = useState(true);
+
+  const { data, isLoading } = useQuery({
+    queryKey: ["case-time-entries", id],
+    queryFn: () =>
+      api.get<{ time_entries: TimeEntry[] }>(`/cases/${id}/time-entries`),
+  });
+
+  const createMutation = useMutation({
+    mutationFn: (input: {
+      description: string;
+      duration_minutes: number;
+      date: string;
+      activity?: string;
+      billable: boolean;
+    }) => api.post<TimeEntry>(`/cases/${id}/time-entries`, input),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["case-time-entries", id] });
+      setShowForm(false);
+      setDesc("");
+      setHours("");
+      setMinutes("");
+      setActivity("");
+      setBillable(true);
+    },
+  });
+
+  const deleteMutation = useMutation({
+    mutationFn: (entryId: string) =>
+      api.delete(`/time-entries/${entryId}`),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["case-time-entries", id] });
+    },
+  });
+
+  function handleSubmit(e: React.FormEvent) {
+    e.preventDefault();
+    const totalMinutes = (parseInt(hours || "0") * 60) + parseInt(minutes || "0");
+    if (totalMinutes <= 0 || !desc.trim()) return;
+    createMutation.mutate({
+      description: desc.trim(),
+      duration_minutes: totalMinutes,
+      date,
+      activity: activity || undefined,
+      billable,
+    });
+  }
+
+  if (isLoading) {
+    return (
+      <div className="flex items-center justify-center py-8">
+        <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+      </div>
+    );
+  }
+
+  const entries = data?.time_entries ?? [];
+  const totalMinutes = entries.reduce((s, e) => s + e.duration_minutes, 0);
+  const billableMinutes = entries
+    .filter((e) => e.billable)
+    .reduce((s, e) => s + e.duration_minutes, 0);
+
+  return (
+    <div className="space-y-4">
+      {/* Summary bar */}
+      <div className="flex flex-wrap items-center justify-between gap-3">
+        <div className="flex gap-6 text-sm text-neutral-500">
+          <span>
+            Gesamt: <span className="font-medium text-neutral-900">{formatDuration(totalMinutes)}</span>
+          </span>
+          <span>
+            Abrechenbar: <span className="font-medium text-neutral-900">{formatDuration(billableMinutes)}</span>
+          </span>
+        </div>
+        <button
+          onClick={() => setShowForm(!showForm)}
+          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"
+        >
+          <Plus className="h-3.5 w-3.5" />
+          Eintrag
+        </button>
+      </div>
+
+      {/* Quick add form */}
+      {showForm && (
+        <form
+          onSubmit={handleSubmit}
+          className="rounded-md border border-neutral-200 bg-neutral-50 p-4 space-y-3"
+        >
+          <div>
+            <label className="block text-xs font-medium text-neutral-600 mb-1">
+              Beschreibung
+            </label>
+            <input
+              type="text"
+              value={desc}
+              onChange={(e) => setDesc(e.target.value)}
+              placeholder="Was wurde getan?"
+              className="w-full rounded-md border border-neutral-300 px-3 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
+              required
+            />
+          </div>
+          <div className="flex flex-wrap gap-3">
+            <div className="flex-1 min-w-[120px]">
+              <label className="block text-xs font-medium text-neutral-600 mb-1">
+                Dauer
+              </label>
+              <div className="flex gap-2">
+                <div className="flex items-center gap-1">
+                  <input
+                    type="number"
+                    min="0"
+                    value={hours}
+                    onChange={(e) => setHours(e.target.value)}
+                    placeholder="0"
+                    className="w-16 rounded-md border border-neutral-300 px-2 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
+                  />
+                  <span className="text-xs text-neutral-500">h</span>
+                </div>
+                <div className="flex items-center gap-1">
+                  <input
+                    type="number"
+                    min="0"
+                    max="59"
+                    value={minutes}
+                    onChange={(e) => setMinutes(e.target.value)}
+                    placeholder="0"
+                    className="w-16 rounded-md border border-neutral-300 px-2 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
+                  />
+                  <span className="text-xs text-neutral-500">min</span>
+                </div>
+              </div>
+            </div>
+            <div className="flex-1 min-w-[120px]">
+              <label className="block text-xs font-medium text-neutral-600 mb-1">
+                Datum
+              </label>
+              <input
+                type="date"
+                value={date}
+                onChange={(e) => setDate(e.target.value)}
+                className="w-full rounded-md border border-neutral-300 px-3 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
+              />
+            </div>
+            <div className="flex-1 min-w-[120px]">
+              <label className="block text-xs font-medium text-neutral-600 mb-1">
+                Kategorie
+              </label>
+              <select
+                value={activity}
+                onChange={(e) => setActivity(e.target.value)}
+                className="w-full rounded-md border border-neutral-300 px-3 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
+              >
+                {ACTIVITIES.map((a) => (
+                  <option key={a.value} value={a.value}>
+                    {a.label}
+                  </option>
+                ))}
+              </select>
+            </div>
+          </div>
+          <div className="flex items-center justify-between">
+            <label className="flex items-center gap-2 text-sm text-neutral-600">
+              <input
+                type="checkbox"
+                checked={billable}
+                onChange={(e) => setBillable(e.target.checked)}
+                className="rounded border-neutral-300"
+              />
+              Abrechenbar
+            </label>
+            <div className="flex gap-2">
+              <button
+                type="button"
+                onClick={() => setShowForm(false)}
+                className="rounded-md px-3 py-1.5 text-sm text-neutral-600 transition-colors hover:bg-neutral-100"
+              >
+                Abbrechen
+              </button>
+              <button
+                type="submit"
+                disabled={createMutation.isPending}
+                className="rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800 disabled:opacity-50"
+              >
+                {createMutation.isPending ? "Speichern..." : "Speichern"}
+              </button>
+            </div>
+          </div>
+          {createMutation.isError && (
+            <p className="text-sm text-red-600">Fehler beim Speichern.</p>
+          )}
+        </form>
+      )}
+
+      {/* Entries list */}
+      {entries.length === 0 ? (
+        <div className="flex flex-col items-center py-8 text-center">
+          <div className="rounded-xl bg-neutral-100 p-3">
+            <Timer className="h-5 w-5 text-neutral-400" />
+          </div>
+          <p className="mt-2 text-sm text-neutral-500">
+            Keine Zeiteintraege vorhanden.
+          </p>
+        </div>
+      ) : (
+        <div className="space-y-2">
+          {entries.map((entry) => (
+            <div
+              key={entry.id}
+              className="flex items-center justify-between rounded-md border border-neutral-200 bg-white px-4 py-3"
+            >
+              <div className="min-w-0 flex-1">
+                <div className="flex items-center gap-2">
+                  <p className="text-sm font-medium text-neutral-900 truncate">
+                    {entry.description}
+                  </p>
+                  {entry.activity && (
+                    <span className="shrink-0 rounded-full bg-neutral-100 px-2 py-0.5 text-xs text-neutral-500">
+                      {ACTIVITIES.find((a) => a.value === entry.activity)?.label ?? entry.activity}
+                    </span>
+                  )}
+                  {!entry.billable && (
+                    <span className="shrink-0 rounded-full bg-neutral-100 px-2 py-0.5 text-xs text-neutral-400">
+                      nicht abrechenbar
+                    </span>
+                  )}
+                  {entry.billed && (
+                    <span className="shrink-0 rounded-full bg-emerald-50 px-2 py-0.5 text-xs text-emerald-700">
+                      abgerechnet
+                    </span>
+                  )}
+                </div>
+                <div className="mt-0.5 flex gap-4 text-xs text-neutral-500">
+                  <span>
+                    {format(new Date(entry.date), "d. MMM yyyy", { locale: de })}
+                  </span>
+                  {entry.hourly_rate && (
+                    <span>{formatAmount(entry.duration_minutes, entry.hourly_rate)}</span>
+                  )}
+                </div>
+              </div>
+              <div className="flex items-center gap-3 ml-4">
+                <span className="text-sm font-medium text-neutral-900 whitespace-nowrap">
+                  {formatDuration(entry.duration_minutes)}
+                </span>
+                {!entry.billed && (
+                  <button
+                    onClick={() => deleteMutation.mutate(entry.id)}
+                    className="rounded-md p-1 text-neutral-400 transition-colors hover:bg-red-50 hover:text-red-600"
+                    title="Loeschen"
+                  >
+                    <Trash2 className="h-3.5 w-3.5" />
+                  </button>
+                )}
+              </div>
+            </div>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}
--- a/frontend/src/app/(app)/einstellungen/abrechnung/page.tsx
+++ b/frontend/src/app/(app)/einstellungen/abrechnung/page.tsx
@@ -0,0 +1,166 @@
+"use client";
+
+import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
+import { api } from "@/lib/api";
+import type { BillingRate } from "@/lib/types";
+import { format } from "date-fns";
+import { de } from "date-fns/locale";
+import { Loader2, Plus } from "lucide-react";
+import { useState } from "react";
+import { Breadcrumb } from "@/components/layout/Breadcrumb";
+
+export default function BillingRatesPage() {
+  const queryClient = useQueryClient();
+  const [showForm, setShowForm] = useState(false);
+  const [rate, setRate] = useState("");
+  const [validFrom, setValidFrom] = useState(format(new Date(), "yyyy-MM-dd"));
+
+  const { data, isLoading } = useQuery({
+    queryKey: ["billing-rates"],
+    queryFn: () =>
+      api.get<{ billing_rates: BillingRate[] }>("/billing-rates"),
+  });
+
+  const upsertMutation = useMutation({
+    mutationFn: (input: { rate: number; valid_from: string; currency: string }) =>
+      api.put<BillingRate>("/billing-rates", input),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["billing-rates"] });
+      setShowForm(false);
+      setRate("");
+    },
+  });
+
+  function handleSubmit(e: React.FormEvent) {
+    e.preventDefault();
+    const rateNum = parseFloat(rate);
+    if (isNaN(rateNum) || rateNum < 0) return;
+    upsertMutation.mutate({
+      rate: rateNum,
+      valid_from: validFrom,
+      currency: "EUR",
+    });
+  }
+
+  const rates = data?.billing_rates ?? [];
+
+  return (
+    <div className="animate-fade-in">
+      <Breadcrumb
+        items={[
+          { label: "Dashboard", href: "/dashboard" },
+          { label: "Einstellungen", href: "/einstellungen" },
+          { label: "Stundensaetze" },
+        ]}
+      />
+
+      <div className="mt-4 flex items-center justify-between">
+        <h1 className="text-lg font-semibold text-neutral-900">
+          Stundensaetze
+        </h1>
+        <button
+          onClick={() => setShowForm(!showForm)}
+          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"
+        >
+          <Plus className="h-3.5 w-3.5" />
+          Neuer Satz
+        </button>
+      </div>
+
+      {showForm && (
+        <form
+          onSubmit={handleSubmit}
+          className="mt-4 rounded-md border border-neutral-200 bg-neutral-50 p-4 space-y-3"
+        >
+          <div className="flex flex-wrap gap-3">
+            <div className="flex-1 min-w-[150px]">
+              <label className="block text-xs font-medium text-neutral-600 mb-1">
+                Stundensatz (EUR)
+              </label>
+              <input
+                type="number"
+                min="0"
+                step="0.01"
+                value={rate}
+                onChange={(e) => setRate(e.target.value)}
+                placeholder="z.B. 350.00"
+                className="w-full rounded-md border border-neutral-300 px-3 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
+                required
+              />
+            </div>
+            <div className="flex-1 min-w-[150px]">
+              <label className="block text-xs font-medium text-neutral-600 mb-1">
+                Gueltig ab
+              </label>
+              <input
+                type="date"
+                value={validFrom}
+                onChange={(e) => setValidFrom(e.target.value)}
+                className="w-full rounded-md border border-neutral-300 px-3 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
+                required
+              />
+            </div>
+          </div>
+          <div className="flex justify-end gap-2">
+            <button
+              type="button"
+              onClick={() => setShowForm(false)}
+              className="rounded-md px-3 py-1.5 text-sm text-neutral-600 hover:bg-neutral-100"
+            >
+              Abbrechen
+            </button>
+            <button
+              type="submit"
+              disabled={upsertMutation.isPending}
+              className="rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white hover:bg-neutral-800 disabled:opacity-50"
+            >
+              Speichern
+            </button>
+          </div>
+        </form>
+      )}
+
+      {isLoading ? (
+        <div className="flex items-center justify-center py-8">
+          <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+        </div>
+      ) : rates.length === 0 ? (
+        <div className="mt-8 text-center">
+          <p className="text-sm text-neutral-500">
+            Noch keine Stundensaetze definiert.
+          </p>
+        </div>
+      ) : (
+        <div className="mt-4 space-y-2">
+          {rates.map((r) => (
+            <div
+              key={r.id}
+              className="flex items-center justify-between rounded-md border border-neutral-200 bg-white px-4 py-3"
+            >
+              <div>
+                <p className="text-sm font-medium text-neutral-900">
+                  {r.rate.toFixed(2)} {r.currency}/h
+                </p>
+                <p className="mt-0.5 text-xs text-neutral-500">
+                  {r.user_id ? `Benutzer: ${r.user_id.slice(0, 8)}...` : "Standard (alle Benutzer)"}
+                </p>
+              </div>
+              <div className="text-right text-xs text-neutral-500">
+                <p>
+                  Ab{" "}
+                  {format(new Date(r.valid_from), "d. MMM yyyy", { locale: de })}
+                </p>
+                {r.valid_to && (
+                  <p>
+                    Bis{" "}
+                    {format(new Date(r.valid_to), "d. MMM yyyy", { locale: de })}
+                  </p>
+                )}
+              </div>
+            </div>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}
--- a/frontend/src/components/ai/CaseStrategy.tsx
+++ b/frontend/src/components/ai/CaseStrategy.tsx
@@ -1,226 +0,0 @@
-"use client";
-
-import { useMutation } from "@tanstack/react-query";
-import { api } from "@/lib/api";
-import type { StrategyRecommendation } from "@/lib/types";
-import {
-  Loader2,
-  Brain,
-  AlertTriangle,
-  ArrowRight,
-  Shield,
-  Calendar,
-  RefreshCw,
-} from "lucide-react";
-
-interface CaseStrategyProps {
-  caseId: string;
-}
-
-const PRIORITY_STYLES = {
-  high: "bg-red-50 text-red-700 border-red-200",
-  medium: "bg-amber-50 text-amber-700 border-amber-200",
-  low: "bg-emerald-50 text-emerald-700 border-emerald-200",
-} as const;
-
-const IMPORTANCE_STYLES = {
-  critical: "border-l-red-500",
-  important: "border-l-amber-500",
-  routine: "border-l-neutral-300",
-} as const;
-
-export function CaseStrategy({ caseId }: CaseStrategyProps) {
-  const mutation = useMutation({
-    mutationFn: () =>
-      api.post<StrategyRecommendation>("/ai/case-strategy", {
-        case_id: caseId,
-      }),
-  });
-
-  if (!mutation.data && !mutation.isPending && !mutation.isError) {
-    return (
-      <div className="flex flex-col items-center gap-3 py-8 text-center">
-        <div className="rounded-xl bg-neutral-100 p-3">
-          <Brain className="h-6 w-6 text-neutral-400" />
-        </div>
-        <div>
-          <p className="text-sm font-medium text-neutral-900">
-            KI-Strategieanalyse
-          </p>
-          <p className="mt-1 text-sm text-neutral-500">
-            Claude analysiert die Akte und gibt strategische Empfehlungen.
-          </p>
-        </div>
-        <button
-          onClick={() => mutation.mutate()}
-          className="inline-flex items-center gap-2 rounded-md bg-neutral-900 px-4 py-2 text-sm font-medium text-white transition-colors hover:bg-neutral-800"
-        >
-          <Brain className="h-4 w-4" />
-          Strategie analysieren
-        </button>
-      </div>
-    );
-  }
-
-  if (mutation.isPending) {
-    return (
-      <div className="flex flex-col items-center gap-3 py-12 text-center">
-        <Loader2 className="h-6 w-6 animate-spin text-neutral-400" />
-        <p className="text-sm text-neutral-500">
-          Claude analysiert die Akte...
-        </p>
-        <p className="text-xs text-neutral-400">
-          Dies kann bis zu 30 Sekunden dauern.
-        </p>
-      </div>
-    );
-  }
-
-  if (mutation.isError) {
-    return (
-      <div className="flex flex-col items-center gap-3 py-8 text-center">
-        <div className="rounded-xl bg-red-50 p-3">
-          <AlertTriangle className="h-6 w-6 text-red-500" />
-        </div>
-        <p className="text-sm text-neutral-900">Analyse fehlgeschlagen</p>
-        <button
-          onClick={() => mutation.mutate()}
-          className="inline-flex items-center gap-1 text-sm text-neutral-500 transition-colors hover:text-neutral-700"
-        >
-          <RefreshCw className="h-3.5 w-3.5" />
-          Erneut versuchen
-        </button>
-      </div>
-    );
-  }
-
-  const data = mutation.data!;
-
-  return (
-    <div className="space-y-6">
-      <div className="flex items-center justify-between">
-        <h3 className="text-sm font-semibold text-neutral-900">
-          KI-Strategieanalyse
-        </h3>
-        <button
-          onClick={() => mutation.mutate()}
-          className="inline-flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1.5 text-xs font-medium text-neutral-600 transition-colors hover:bg-neutral-50"
-        >
-          <RefreshCw className="h-3.5 w-3.5" />
-          Aktualisieren
-        </button>
-      </div>
-
-      {/* Summary */}
-      <div className="rounded-md border border-blue-100 bg-blue-50 px-4 py-3 text-sm text-blue-800">
-        {data.summary}
-      </div>
-
-      {/* Next Steps */}
-      {data.next_steps?.length > 0 && (
-        <div>
-          <h4 className="mb-2 flex items-center gap-1.5 text-xs font-semibold uppercase tracking-wide text-neutral-500">
-            <ArrowRight className="h-3.5 w-3.5" />
-            Naechste Schritte
-          </h4>
-          <div className="space-y-2">
-            {data.next_steps.map((step, i) => (
-              <div
-                key={i}
-                className="rounded-md border border-neutral-200 bg-white px-4 py-3"
-              >
-                <div className="flex items-start gap-3">
-                  <span
-                    className={`mt-0.5 inline-block shrink-0 rounded-full border px-2 py-0.5 text-xs font-medium ${PRIORITY_STYLES[step.priority]}`}
-                  >
-                    {step.priority === "high"
-                      ? "Hoch"
-                      : step.priority === "medium"
-                        ? "Mittel"
-                        : "Niedrig"}
-                  </span>
-                  <div className="min-w-0">
-                    <p className="text-sm font-medium text-neutral-900">
-                      {step.action}
-                    </p>
-                    <p className="mt-1 text-sm text-neutral-500">
-                      {step.reasoning}
-                    </p>
-                    {step.deadline && (
-                      <p className="mt-1 text-xs text-neutral-400">
-                        Frist: {step.deadline}
-                      </p>
-                    )}
-                  </div>
-                </div>
-              </div>
-            ))}
-          </div>
-        </div>
-      )}
-
-      {/* Risk Assessment */}
-      {data.risk_assessment?.length > 0 && (
-        <div>
-          <h4 className="mb-2 flex items-center gap-1.5 text-xs font-semibold uppercase tracking-wide text-neutral-500">
-            <Shield className="h-3.5 w-3.5" />
-            Risikobewertung
-          </h4>
-          <div className="space-y-2">
-            {data.risk_assessment.map((risk, i) => (
-              <div
-                key={i}
-                className="rounded-md border border-neutral-200 bg-white px-4 py-3"
-              >
-                <div className="flex items-start gap-3">
-                  <span
-                    className={`mt-0.5 inline-block shrink-0 rounded-full border px-2 py-0.5 text-xs font-medium ${PRIORITY_STYLES[risk.level]}`}
-                  >
-                    {risk.level === "high"
-                      ? "Hoch"
-                      : risk.level === "medium"
-                        ? "Mittel"
-                        : "Niedrig"}
-                  </span>
-                  <div className="min-w-0">
-                    <p className="text-sm font-medium text-neutral-900">
-                      {risk.risk}
-                    </p>
-                    <p className="mt-1 text-sm text-neutral-500">
-                      Massnahme: {risk.mitigation}
-                    </p>
-                  </div>
-                </div>
-              </div>
-            ))}
-          </div>
-        </div>
-      )}
-
-      {/* Timeline */}
-      {data.timeline?.length > 0 && (
-        <div>
-          <h4 className="mb-2 flex items-center gap-1.5 text-xs font-semibold uppercase tracking-wide text-neutral-500">
-            <Calendar className="h-3.5 w-3.5" />
-            Zeitplan
-          </h4>
-          <div className="space-y-1">
-            {data.timeline.map((item, i) => (
-              <div
-                key={i}
-                className={`border-l-2 py-2 pl-4 ${IMPORTANCE_STYLES[item.importance]}`}
-              >
-                <div className="flex items-baseline gap-2">
-                  <span className="shrink-0 text-xs font-medium text-neutral-400">
-                    {item.date}
-                  </span>
-                  <span className="text-sm text-neutral-900">{item.event}</span>
-                </div>
-              </div>
-            ))}
-          </div>
-        </div>
-      )}
-    </div>
-  );
-}
--- a/frontend/src/components/ai/DocumentDrafter.tsx
+++ b/frontend/src/components/ai/DocumentDrafter.tsx
@@ -1,198 +0,0 @@
-"use client";
-
-import { useState } from "react";
-import { useMutation } from "@tanstack/react-query";
-import { api } from "@/lib/api";
-import type { DocumentDraft, DraftDocumentRequest } from "@/lib/types";
-import { FileText, Loader2, Copy, Check, Download } from "lucide-react";
-
-const TEMPLATES = {
-  klageschrift: "Klageschrift",
-  klageerwiderung: "Klageerwiderung",
-  abmahnung: "Abmahnung",
-  schriftsatz: "Schriftsatz",
-  berufung: "Berufungsschrift",
-  antrag: "Antrag",
-  stellungnahme: "Stellungnahme",
-  gutachten: "Gutachten",
-  vertrag: "Vertrag",
-  vollmacht: "Vollmacht",
-  upc_claim: "UPC Statement of Claim",
-  upc_defence: "UPC Statement of Defence",
-  upc_counterclaim: "UPC Counterclaim for Revocation",
-  upc_injunction: "UPC Provisional Measures",
-} as const;
-
-const LANGUAGES = [
-  { value: "de", label: "Deutsch" },
-  { value: "en", label: "English" },
-  { value: "fr", label: "Francais" },
-] as const;
-
-const inputClass =
-  "w-full rounded-md border border-neutral-200 bg-white px-3 py-2 text-sm text-neutral-900 outline-none transition-colors focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400";
-
-interface DocumentDrafterProps {
-  caseId: string;
-}
-
-export function DocumentDrafter({ caseId }: DocumentDrafterProps) {
-  const [templateType, setTemplateType] = useState("");
-  const [instructions, setInstructions] = useState("");
-  const [language, setLanguage] = useState("de");
-  const [copied, setCopied] = useState(false);
-
-  const mutation = useMutation({
-    mutationFn: (req: DraftDocumentRequest) =>
-      api.post<DocumentDraft>("/ai/draft-document", req),
-  });
-
-  function handleSubmit(e: React.FormEvent) {
-    e.preventDefault();
-    if (!templateType) return;
-    mutation.mutate({
-      case_id: caseId,
-      template_type: templateType,
-      instructions,
-      language,
-    });
-  }
-
-  function handleCopy() {
-    if (mutation.data?.content) {
-      navigator.clipboard.writeText(mutation.data.content);
-      setCopied(true);
-      setTimeout(() => setCopied(false), 2000);
-    }
-  }
-
-  function handleDownload() {
-    if (!mutation.data?.content) return;
-    const blob = new Blob([mutation.data.content], { type: "text/plain;charset=utf-8" });
-    const url = URL.createObjectURL(blob);
-    const a = document.createElement("a");
-    a.href = url;
-    a.download = `${templateType}_entwurf.txt`;
-    a.click();
-    URL.revokeObjectURL(url);
-  }
-
-  return (
-    <div className="space-y-4">
-      <form onSubmit={handleSubmit} className="space-y-3">
-        <div>
-          <label className="mb-1 block text-xs font-medium text-neutral-500">
-            Dokumenttyp
-          </label>
-          <select
-            value={templateType}
-            onChange={(e) => setTemplateType(e.target.value)}
-            className={inputClass}
-            disabled={mutation.isPending}
-          >
-            <option value="">Dokumenttyp waehlen...</option>
-            {Object.entries(TEMPLATES).map(([key, label]) => (
-              <option key={key} value={key}>
-                {label}
-              </option>
-            ))}
-          </select>
-        </div>
-
-        <div>
-          <label className="mb-1 block text-xs font-medium text-neutral-500">
-            Sprache
-          </label>
-          <select
-            value={language}
-            onChange={(e) => setLanguage(e.target.value)}
-            className={inputClass}
-            disabled={mutation.isPending}
-          >
-            {LANGUAGES.map((lang) => (
-              <option key={lang.value} value={lang.value}>
-                {lang.label}
-              </option>
-            ))}
-          </select>
-        </div>
-
-        <div>
-          <label className="mb-1 block text-xs font-medium text-neutral-500">
-            Anweisungen (optional)
-          </label>
-          <textarea
-            value={instructions}
-            onChange={(e) => setInstructions(e.target.value)}
-            placeholder="z.B. 'Fokus auf Patentanspruch 1, besonders die technischen Merkmale...'"
-            rows={3}
-            className={inputClass}
-            disabled={mutation.isPending}
-          />
-        </div>
-
-        <button
-          type="submit"
-          disabled={!templateType || mutation.isPending}
-          className="inline-flex items-center gap-2 rounded-md bg-neutral-900 px-4 py-2 text-sm font-medium text-white transition-colors hover:bg-neutral-800 disabled:opacity-50"
-        >
-          {mutation.isPending ? (
-            <>
-              <Loader2 className="h-4 w-4 animate-spin" />
-              Dokument wird erstellt...
-            </>
-          ) : (
-            <>
-              <FileText className="h-4 w-4" />
-              KI-Entwurf erstellen
-            </>
-          )}
-        </button>
-      </form>
-
-      {mutation.isError && (
-        <div className="rounded-md border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-700">
-          Fehler beim Erstellen des Entwurfs. Bitte versuchen Sie es erneut.
-        </div>
-      )}
-
-      {mutation.data && (
-        <div className="space-y-3">
-          <div className="flex items-center justify-between">
-            <h4 className="text-sm font-medium text-neutral-900">
-              {mutation.data.title}
-            </h4>
-            <div className="flex items-center gap-2">
-              <button
-                onClick={handleCopy}
-                className="inline-flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1.5 text-xs font-medium text-neutral-600 transition-colors hover:bg-neutral-50"
-              >
-                {copied ? (
-                  <>
-                    <Check className="h-3.5 w-3.5 text-emerald-500" />
-                    Kopiert
-                  </>
-                ) : (
-                  <>
-                    <Copy className="h-3.5 w-3.5" />
-                    Kopieren
-                  </>
-                )}
-              </button>
-              <button
-                onClick={handleDownload}
-                className="inline-flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1.5 text-xs font-medium text-neutral-600 transition-colors hover:bg-neutral-50"
-              >
-                <Download className="h-3.5 w-3.5" />
-                Download
-              </button>
-            </div>
-          </div>
-          <pre className="max-h-[600px] overflow-auto whitespace-pre-wrap rounded-md border border-neutral-200 bg-neutral-50 p-4 text-sm text-neutral-800">
-            {mutation.data.content}
-          </pre>
-        </div>
-      )}
-    </div>
-  );
-}
--- a/frontend/src/components/ai/SimilarCaseFinder.tsx
+++ b/frontend/src/components/ai/SimilarCaseFinder.tsx
@@ -1,183 +0,0 @@
-"use client";
-
-import { useState } from "react";
-import { useMutation } from "@tanstack/react-query";
-import { api } from "@/lib/api";
-import type { SimilarCasesResponse } from "@/lib/types";
-import {
-  Loader2,
-  Search,
-  ExternalLink,
-  AlertTriangle,
-  Scale,
-  RefreshCw,
-} from "lucide-react";
-
-interface SimilarCaseFinderProps {
-  caseId: string;
-}
-
-const inputClass =
-  "w-full rounded-md border border-neutral-200 bg-white px-3 py-2 text-sm text-neutral-900 outline-none transition-colors focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400";
-
-function RelevanceBadge({ score }: { score: number }) {
-  const pct = Math.round(score * 100);
-  let color = "bg-neutral-100 text-neutral-600";
-  if (pct >= 80) color = "bg-emerald-50 text-emerald-700";
-  else if (pct >= 60) color = "bg-blue-50 text-blue-700";
-  else if (pct >= 40) color = "bg-amber-50 text-amber-700";
-  return (
-    <span
-      className={`inline-block shrink-0 rounded-full px-2 py-0.5 text-xs font-medium ${color}`}
-    >
-      {pct}%
-    </span>
-  );
-}
-
-export function SimilarCaseFinder({ caseId }: SimilarCaseFinderProps) {
-  const [description, setDescription] = useState("");
-
-  const mutation = useMutation({
-    mutationFn: (req: { case_id: string; description: string }) =>
-      api.post<SimilarCasesResponse>("/ai/similar-cases", req),
-  });
-
-  function handleSearch(e?: React.FormEvent) {
-    e?.preventDefault();
-    mutation.mutate({ case_id: caseId, description });
-  }
-
-  return (
-    <div className="space-y-4">
-      <form onSubmit={handleSearch} className="space-y-3">
-        <div>
-          <label className="mb-1 block text-xs font-medium text-neutral-500">
-            Zusaetzliche Beschreibung (optional)
-          </label>
-          <textarea
-            value={description}
-            onChange={(e) => setDescription(e.target.value)}
-            placeholder="z.B. 'SEP-Lizenzierung im Mobilfunkbereich, FRAND-Verteidigung...'"
-            rows={2}
-            className={inputClass}
-            disabled={mutation.isPending}
-          />
-        </div>
-
-        <button
-          type="submit"
-          disabled={mutation.isPending}
-          className="inline-flex items-center gap-2 rounded-md bg-neutral-900 px-4 py-2 text-sm font-medium text-white transition-colors hover:bg-neutral-800 disabled:opacity-50"
-        >
-          {mutation.isPending ? (
-            <>
-              <Loader2 className="h-4 w-4 animate-spin" />
-              Suche laeuft...
-            </>
-          ) : (
-            <>
-              <Search className="h-4 w-4" />
-              Aehnliche Faelle suchen
-            </>
-          )}
-        </button>
-      </form>
-
-      {mutation.isError && (
-        <div className="flex flex-col items-center gap-3 py-6 text-center">
-          <div className="rounded-xl bg-red-50 p-3">
-            <AlertTriangle className="h-6 w-6 text-red-500" />
-          </div>
-          <p className="text-sm text-neutral-900">Suche fehlgeschlagen</p>
-          <p className="text-xs text-neutral-500">
-            Die youpc.org-Datenbank ist moeglicherweise nicht verfuegbar.
-          </p>
-          <button
-            onClick={() => handleSearch()}
-            className="inline-flex items-center gap-1 text-sm text-neutral-500 transition-colors hover:text-neutral-700"
-          >
-            <RefreshCw className="h-3.5 w-3.5" />
-            Erneut versuchen
-          </button>
-        </div>
-      )}
-
-      {mutation.data && (
-        <div className="space-y-3">
-          <div className="flex items-center justify-between">
-            <p className="text-xs text-neutral-500">
-              {mutation.data.count} aehnliche{" "}
-              {mutation.data.count === 1 ? "Fall" : "Faelle"} gefunden
-            </p>
-            <button
-              onClick={() => handleSearch()}
-              disabled={mutation.isPending}
-              className="inline-flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1.5 text-xs font-medium text-neutral-600 transition-colors hover:bg-neutral-50"
-            >
-              <RefreshCw className="h-3.5 w-3.5" />
-              Aktualisieren
-            </button>
-          </div>
-
-          {mutation.data.cases?.length === 0 && (
-            <div className="flex flex-col items-center gap-2 py-6 text-center">
-              <Scale className="h-6 w-6 text-neutral-300" />
-              <p className="text-sm text-neutral-500">
-                Keine aehnlichen UPC-Faelle gefunden.
-              </p>
-            </div>
-          )}
-
-          {mutation.data.cases?.map((c, i) => (
-            <div
-              key={i}
-              className="rounded-md border border-neutral-200 bg-white px-4 py-3"
-            >
-              <div className="flex items-start justify-between gap-3">
-                <div className="min-w-0 flex-1">
-                  <div className="flex items-center gap-2">
-                    <RelevanceBadge score={c.relevance} />
-                    <span className="text-xs font-medium text-neutral-400">
-                      {c.case_number}
-                    </span>
-                    {c.url && (
-                      <a
-                        href={c.url}
-                        target="_blank"
-                        rel="noopener noreferrer"
-                        className="text-neutral-400 transition-colors hover:text-neutral-600"
-                      >
-                        <ExternalLink className="h-3.5 w-3.5" />
-                      </a>
-                    )}
-                  </div>
-                  <p className="mt-1 text-sm font-medium text-neutral-900">
-                    {c.title}
-                  </p>
-                  <div className="mt-1 flex flex-wrap gap-x-3 text-xs text-neutral-400">
-                    {c.court && <span>{c.court}</span>}
-                    {c.date && <span>{c.date}</span>}
-                  </div>
-                </div>
-              </div>
-
-              <p className="mt-2 text-sm text-neutral-600">{c.explanation}</p>
-
-              {c.key_holdings && (
-                <div className="mt-2 rounded border border-neutral-100 bg-neutral-50 px-3 py-2">
-                  <p className="text-xs font-medium text-neutral-500">
-                    Relevante Entscheidungsgruende
-                  </p>
-                  <p className="mt-0.5 text-xs text-neutral-600">
-                    {c.key_holdings}
-                  </p>
-                </div>
-              )}
-            </div>
-          ))}
-        </div>
-      )}
-    </div>
-  );
-}
--- a/frontend/src/components/layout/Sidebar.tsx
+++ b/frontend/src/components/layout/Sidebar.tsx
@@ -11,6 +11,7 @@ import {
  Settings,
  Menu,
  X,
+  Receipt,
 } from "lucide-react";
 import { useState, useEffect } from "react";
 import { usePermissions } from "@/lib/hooks/usePermissions";
@@ -27,6 +28,7 @@ const allNavigation: NavItem[] = [
  { name: "Akten", href: "/cases", icon: FolderOpen },
  { name: "Fristen", href: "/fristen", icon: Clock },
  { name: "Termine", href: "/termine", icon: Calendar },
+  { name: "Abrechnung", href: "/abrechnung", icon: Receipt, permission: "manage_billing" },
  { name: "AI Analyse", href: "/ai/extract", icon: Brain, permission: "ai_extraction" },
  { name: "Einstellungen", href: "/einstellungen", icon: Settings, permission: "manage_settings" },
 ];
--- a/frontend/src/lib/types.ts
+++ b/frontend/src/lib/types.ts
@@ -223,6 +223,125 @@ export const CASE_ASSIGNMENT_ROLE_LABELS: Record<CaseAssignmentRole, string> = {
  viewer: "Einsicht",
 };

+// Time tracking & billing
+
+export interface TimeEntry {
+  id: string;
+  tenant_id: string;
+  case_id: string;
+  user_id: string;
+  date: string;
+  duration_minutes: number;
+  description: string;
+  activity?: string;
+  billable: boolean;
+  billed: boolean;
+  invoice_id?: string;
+  hourly_rate?: number;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface BillingRate {
+  id: string;
+  tenant_id: string;
+  user_id?: string;
+  rate: number;
+  currency: string;
+  valid_from: string;
+  valid_to?: string;
+  created_at: string;
+}
+
+export interface InvoiceItem {
+  description: string;
+  duration_minutes?: number;
+  hourly_rate?: number;
+  amount: number;
+  time_entry_id?: string;
+}
+
+export interface Invoice {
+  id: string;
+  tenant_id: string;
+  case_id: string;
+  invoice_number: string;
+  client_name: string;
+  client_address?: string;
+  items: InvoiceItem[];
+  subtotal: number;
+  tax_rate: number;
+  tax_amount: number;
+  total: number;
+  status: "draft" | "sent" | "paid" | "cancelled";
+  issued_at?: string;
+  due_at?: string;
+  paid_at?: string;
+  notes?: string;
+  created_by: string;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface TimeEntrySummary {
+  group_key: string;
+  total_minutes: number;
+  billable_minutes: number;
+  total_amount: number;
+  entry_count: number;
+}
+
+// Notifications
+export interface Notification {
+  id: string;
+  tenant_id: string;
+  user_id: string;
+  type: string;
+  title: string;
+  body?: string;
+  entity_type?: string;
+  entity_id?: string;
+  sent_at?: string;
+  read_at?: string;
+  created_at: string;
+}
+
+export interface NotificationPreferences {
+  user_id: string;
+  tenant_id: string;
+  deadline_reminder_days: number[];
+  email_enabled: boolean;
+  daily_digest: boolean;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface NotificationListResponse {
+  notifications: Notification[];
+  data: Notification[];
+  total: number;
+}
+
+// Audit log
+export interface AuditLogEntry {
+  id: number;
+  tenant_id: string;
+  user_id?: string;
+  action: string;
+  entity_type: string;
+  entity_id?: string;
+  old_values?: Record<string, unknown>;
+  new_values?: Record<string, unknown>;
+  ip_address?: string;
+  user_agent?: string;
+  created_at: string;
+}
+
+export interface AuditLogResponse {
+  entries: AuditLogEntry[];
+  total: number;
+}
+
 export interface ApiError {
  error: string;
  status: number;
@@ -329,81 +448,3 @@ export interface ExtractionResponse {
  deadlines: ExtractedDeadline[];
  count: number;
 }
-
-// AI Document Drafting
-
-export interface DocumentDraft {
-  title: string;
-  content: string;
-  language: string;
-}
-
-export interface DraftDocumentRequest {
-  case_id: string;
-  template_type: string;
-  instructions: string;
-  language: string;
-}
-
-export const TEMPLATE_TYPES: Record<string, string> = {
-  klageschrift: "Klageschrift",
-  klageerwiderung: "Klageerwiderung",
-  abmahnung: "Abmahnung",
-  schriftsatz: "Schriftsatz",
-  berufung: "Berufungsschrift",
-  antrag: "Antrag",
-  stellungnahme: "Stellungnahme",
-  gutachten: "Gutachten",
-  vertrag: "Vertrag",
-  vollmacht: "Vollmacht",
-  upc_claim: "UPC Statement of Claim",
-  upc_defence: "UPC Statement of Defence",
-  upc_counterclaim: "UPC Counterclaim for Revocation",
-  upc_injunction: "UPC Provisional Measures",
-};
-
-// AI Case Strategy
-
-export interface StrategyStep {
-  priority: "high" | "medium" | "low";
-  action: string;
-  reasoning: string;
-  deadline?: string;
-}
-
-export interface RiskItem {
-  level: "high" | "medium" | "low";
-  risk: string;
-  mitigation: string;
-}
-
-export interface TimelineItem {
-  date: string;
-  event: string;
-  importance: "critical" | "important" | "routine";
-}
-
-export interface StrategyRecommendation {
-  summary: string;
-  next_steps: StrategyStep[];
-  risk_assessment: RiskItem[];
-  timeline: TimelineItem[];
-}
-
-// AI Similar Case Finder
-
-export interface SimilarCase {
-  case_number: string;
-  title: string;
-  court: string;
-  date: string;
-  relevance: number;
-  explanation: string;
-  key_holdings: string;
-  url?: string;
-}
-
-export interface SimilarCasesResponse {
-  cases: SimilarCase[];
-  count: number;
-}