feat: UPC deadline determination — event-driven model with proceeding timeline

Full event-driven deadline determination system ported from youpc.org:

Backend:
- DetermineService: walks proceeding event tree, calculates cascading
  dates with holiday adjustment and conditional logic
- GET /api/proceeding-types/{code}/timeline — full event tree structure
- POST /api/deadlines/determine — calculate timeline with conditions
- POST /api/cases/{caseID}/deadlines/batch — batch-create deadlines
- DeadlineRule model: added is_spawn, spawn_label fields
- GetFullTimeline: recursive CTE following cross-type spawn branches
- Conditional deadlines: condition_rule_id toggles alt_duration/rule_code
  (e.g. Reply changes from RoP.029b to RoP.029a when CCR is filed)
- Seed SQL with full UPC event trees (INF, REV, CCR, APM, APP, AMD)

Frontend:
- DeadlineWizard: interactive proceeding timeline with step-by-step flow
  1. Select proceeding type (visual cards)
  2. Enter trigger event date
  3. Toggle conditional branches (CCR, Appeal, Amend)
  4. See full calculated timeline with color-coded urgency
  5. Batch-create all deadlines on a selected case
- Visual timeline tree with party icons, rule codes, duration badges
- Kept existing DeadlineCalculator as "Schnell" quick mode

Also resolved merge conflicts across 6 files (auth, router, handlers)
merging role-based permissions + audit trail features.

backend/cmd/server/main.go

@@ -36,7 +36,12 @@ func main() {
 	calDAVSvc.Start()
 	defer calDAVSvc.Stop()
 
-	handler := router.New(database, authMW, cfg, calDAVSvc)
+	// Start notification reminder service
+	notifSvc := services.NewNotificationService(database)
+	notifSvc.Start()
+	defer notifSvc.Stop()
+
+	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 {

backend/internal/auth/context.go

@@ -9,9 +9,11 @@ import (
 type contextKey string
 
 const (
-	userIDKey   contextKey = "user_id"
-	tenantIDKey contextKey = "tenant_id"
-	userRoleKey contextKey = "user_role"
+	userIDKey    contextKey = "user_id"
+	tenantIDKey  contextKey = "tenant_id"
+	ipKey        contextKey = "ip_address"
+	userAgentKey contextKey = "user_agent"
+	userRoleKey  contextKey = "user_role"
 )
 
 func ContextWithUserID(ctx context.Context, userID uuid.UUID) context.Context {
@@ -32,6 +34,26 @@ func TenantFromContext(ctx context.Context) (uuid.UUID, bool) {
 	return id, ok
 }
 
+func ContextWithRequestInfo(ctx context.Context, ip, userAgent string) context.Context {
+	ctx = context.WithValue(ctx, ipKey, ip)
+	ctx = context.WithValue(ctx, userAgentKey, userAgent)
+	return ctx
+}
+
+func IPFromContext(ctx context.Context) *string {
+	if v, ok := ctx.Value(ipKey).(string); ok && v != "" {
+		return &v
+	}
+	return nil
+}
+
+func UserAgentFromContext(ctx context.Context) *string {
+	if v, ok := ctx.Value(userAgentKey).(string); ok && v != "" {
+		return &v
+	}
+	return nil
+}
+
 func ContextWithUserRole(ctx context.Context, role string) context.Context {
 	return context.WithValue(ctx, userRoleKey, role)
 }

backend/internal/auth/middleware.go

@@ -24,32 +24,26 @@ func (m *Middleware) RequireAuth(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		token := extractBearerToken(r)
 		if token == "" {
-			http.Error(w, "missing authorization token", http.StatusUnauthorized)
+			http.Error(w, `{"error":"missing authorization token"}`, http.StatusUnauthorized)
 			return
 		}
 
 		userID, err := m.verifyJWT(token)
 		if err != nil {
-			http.Error(w, fmt.Sprintf("invalid token: %v", err), http.StatusUnauthorized)
+			http.Error(w, `{"error":"invalid token"}`, http.StatusUnauthorized)
 			return
 		}
 
 		ctx := ContextWithUserID(r.Context(), userID)
 
-		// Resolve tenant and role from user_tenants
-		var membership struct {
-			TenantID uuid.UUID `db:"tenant_id"`
-			Role     string    `db:"role"`
+		// Capture IP and user-agent for audit logging
+		ip := r.Header.Get("X-Forwarded-For")
+		if ip == "" {
+			ip = r.RemoteAddr
 		}
-		err = m.db.GetContext(r.Context(), &membership,
-			"SELECT tenant_id, role FROM user_tenants WHERE user_id = $1 LIMIT 1", userID)
-		if err != nil {
-			http.Error(w, "no tenant found for user", http.StatusForbidden)
-			return
-		}
-		ctx = ContextWithTenantID(ctx, membership.TenantID)
-		ctx = ContextWithUserRole(ctx, membership.Role)
+		ctx = ContextWithRequestInfo(ctx, ip, r.UserAgent())
 
+		// Tenant and role resolution handled by TenantResolver middleware for scoped routes.
 		next.ServeHTTP(w, r.WithContext(ctx))
 	})
 }

backend/internal/auth/tenant_resolver.go

@@ -2,13 +2,13 @@ package auth
 
 import (
 	"context"
-	"fmt"
+	"log/slog"
 	"net/http"
 
 	"github.com/google/uuid"
 )
 
-// TenantLookup resolves the default tenant for a user.
+// TenantLookup resolves and verifies tenant access for a user.
 // Defined as an interface to avoid circular dependency with services.
 type TenantLookup interface {
 	FirstTenantForUser(ctx context.Context, userID uuid.UUID) (*uuid.UUID, error)
@@ -16,7 +16,7 @@ type TenantLookup interface {
 }
 
 // TenantResolver is middleware that resolves the tenant from X-Tenant-ID header
-// or defaults to the user's first tenant.
+// or defaults to the user's first tenant. Always verifies user has access.
 type TenantResolver struct {
 	lookup TenantLookup
 }
@@ -29,46 +29,59 @@ func (tr *TenantResolver) Resolve(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		userID, ok := UserFromContext(r.Context())
 		if !ok {
-			http.Error(w, "unauthorized", http.StatusUnauthorized)
+			http.Error(w, `{"error":"unauthorized"}`, http.StatusUnauthorized)
 			return
 		}
 
 		var tenantID uuid.UUID
+		ctx := r.Context()
 
 		if header := r.Header.Get("X-Tenant-ID"); header != "" {
 			parsed, err := uuid.Parse(header)
 			if err != nil {
-				http.Error(w, fmt.Sprintf("invalid X-Tenant-ID: %v", err), http.StatusBadRequest)
+				http.Error(w, `{"error":"invalid X-Tenant-ID"}`, http.StatusBadRequest)
 				return
 			}
+
 			// Verify user has access and get their role
 			role, err := tr.lookup.GetUserRole(r.Context(), userID, parsed)
 			if err != nil {
-				http.Error(w, "error checking tenant access", http.StatusInternalServerError)
+				slog.Error("tenant access check failed", "error", err, "user_id", userID, "tenant_id", parsed)
+				http.Error(w, `{"error":"internal error"}`, http.StatusInternalServerError)
 				return
 			}
 			if role == "" {
-				http.Error(w, "no access to this tenant", http.StatusForbidden)
+				http.Error(w, `{"error":"no access to tenant"}`, http.StatusForbidden)
 				return
 			}
+
 			tenantID = parsed
-			// Override the role from middleware with the correct one for this tenant
-			r = r.WithContext(ContextWithUserRole(r.Context(), role))
+			ctx = ContextWithUserRole(ctx, 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 {
-				http.Error(w, fmt.Sprintf("resolving tenant: %v", err), http.StatusInternalServerError)
+				slog.Error("failed to resolve default tenant", "error", err, "user_id", userID)
+				http.Error(w, `{"error":"internal error"}`, http.StatusInternalServerError)
 				return
 			}
 			if first == nil {
-				http.Error(w, "no tenant found for user", http.StatusBadRequest)
+				http.Error(w, `{"error":"no tenant found for user"}`, http.StatusBadRequest)
 				return
 			}
 			tenantID = *first
+
+			// Look up role for default tenant
+			role, err := tr.lookup.GetUserRole(r.Context(), userID, tenantID)
+			if err != nil {
+				slog.Error("failed to get user role", "error", err, "user_id", userID, "tenant_id", tenantID)
+				http.Error(w, `{"error":"internal error"}`, http.StatusInternalServerError)
+				return
+			}
+			ctx = ContextWithUserRole(ctx, role)
 		}
 
-		ctx := ContextWithTenantID(r.Context(), tenantID)
+		ctx = ContextWithTenantID(ctx, tenantID)
 		next.ServeHTTP(w, r.WithContext(ctx))
 	})
 }

backend/internal/auth/tenant_resolver_test.go

@@ -20,10 +20,7 @@ func (m *mockTenantLookup) FirstTenantForUser(ctx context.Context, userID uuid.U
 }
 
 func (m *mockTenantLookup) GetUserRole(ctx context.Context, userID, tenantID uuid.UUID) (string, error) {
-	if m.role != "" {
-		return m.role, m.err
-	}
-	return "associate", m.err
+	return m.role, m.err
 }
 
 func TestTenantResolver_FromHeader(t *testing.T) {
@@ -31,12 +28,14 @@ func TestTenantResolver_FromHeader(t *testing.T) {
 	tr := NewTenantResolver(&mockTenantLookup{role: "partner"})
 
 	var gotTenantID uuid.UUID
+	var gotRole string
 	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		id, ok := TenantFromContext(r.Context())
 		if !ok {
 			t.Fatal("tenant ID not in context")
 		}
 		gotTenantID = id
+		gotRole = UserRoleFromContext(r.Context())
 		w.WriteHeader(http.StatusOK)
 	})
 
@@ -53,11 +52,34 @@ func TestTenantResolver_FromHeader(t *testing.T) {
 	if gotTenantID != tenantID {
 		t.Errorf("expected tenant %s, got %s", tenantID, gotTenantID)
 	}
+	if gotRole != "partner" {
+		t.Errorf("expected role partner, got %s", gotRole)
+	}
+}
+
+func TestTenantResolver_FromHeader_NoAccess(t *testing.T) {
+	tenantID := uuid.New()
+	tr := NewTenantResolver(&mockTenantLookup{role: ""})
+
+	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		t.Fatal("next should not be called")
+	})
+
+	r := httptest.NewRequest("GET", "/api/cases", nil)
+	r.Header.Set("X-Tenant-ID", tenantID.String())
+	r = r.WithContext(ContextWithUserID(r.Context(), uuid.New()))
+	w := httptest.NewRecorder()
+
+	tr.Resolve(next).ServeHTTP(w, r)
+
+	if w.Code != http.StatusForbidden {
+		t.Errorf("expected 403, got %d", w.Code)
+	}
 }
 
 func TestTenantResolver_DefaultsToFirst(t *testing.T) {
 	tenantID := uuid.New()
-	tr := NewTenantResolver(&mockTenantLookup{tenantID: &tenantID})
+	tr := NewTenantResolver(&mockTenantLookup{tenantID: &tenantID, role: "associate"})
 
 	var gotTenantID uuid.UUID
 	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

backend/internal/config/config.go

@@ -13,6 +13,7 @@ type Config struct {
 	SupabaseServiceKey string
 	SupabaseJWTSecret string
 	AnthropicAPIKey   string
+	FrontendOrigin    string
 }
 
 func Load() (*Config, error) {
@@ -24,6 +25,7 @@ func Load() (*Config, error) {
 		SupabaseServiceKey: os.Getenv("SUPABASE_SERVICE_KEY"),
 		SupabaseJWTSecret: os.Getenv("SUPABASE_JWT_SECRET"),
 		AnthropicAPIKey:  os.Getenv("ANTHROPIC_API_KEY"),
+		FrontendOrigin:   getEnv("FRONTEND_ORIGIN", "https://kanzlai.msbls.de"),
 	}
 
 	if cfg.DatabaseURL == "" {

backend/internal/handlers/ai.go

@@ -5,18 +5,16 @@ import (
 	"io"
 	"net/http"
 
-	"github.com/jmoiron/sqlx"
-
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
 )
 
 type AIHandler struct {
 	ai *services.AIService
-	db *sqlx.DB
 }
 
-func NewAIHandler(ai *services.AIService, db *sqlx.DB) *AIHandler {
-	return &AIHandler{ai: ai, db: db}
+func NewAIHandler(ai *services.AIService) *AIHandler {
+	return &AIHandler{ai: ai}
 }
 
 // ExtractDeadlines handles POST /api/ai/extract-deadlines
@@ -61,10 +59,14 @@ func (h *AIHandler) ExtractDeadlines(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "provide either a PDF file or text")
 		return
 	}
+	if len(text) > maxDescriptionLen {
+		writeError(w, http.StatusBadRequest, "text exceeds maximum length")
+		return
+	}
 
 	deadlines, err := h.ai.ExtractDeadlines(r.Context(), pdfData, text)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, "AI extraction failed: "+err.Error())
+		internalError(w, "AI deadline extraction failed", err)
 		return
 	}
 
@@ -77,9 +79,9 @@ func (h *AIHandler) ExtractDeadlines(w http.ResponseWriter, r *http.Request) {
 // SummarizeCase handles POST /api/ai/summarize-case
 // Accepts JSON {"case_id": "uuid"}.
 func (h *AIHandler) SummarizeCase(w http.ResponseWriter, r *http.Request) {
-	tenantID, err := resolveTenant(r, h.db)
-	if err != nil {
-		handleTenantError(w, err)
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
 		return
 	}
 
@@ -104,7 +106,7 @@ func (h *AIHandler) SummarizeCase(w http.ResponseWriter, r *http.Request) {
 
 	summary, err := h.ai.SummarizeCase(r.Context(), tenantID, caseID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, "AI summarization failed: "+err.Error())
+		internalError(w, "AI case summarization failed", err)
 		return
 	}
 

backend/internal/handlers/ai_handler_test.go

@@ -42,7 +42,7 @@ func TestAIExtractDeadlines_InvalidJSON(t *testing.T) {
 	}
 }
 
-func TestAISummarizeCase_MissingCaseID(t *testing.T) {
+func TestAISummarizeCase_MissingTenant(t *testing.T) {
 	h := &AIHandler{}
 
 	body := `{"case_id":""}`
@@ -52,9 +52,9 @@ func TestAISummarizeCase_MissingCaseID(t *testing.T) {
 
 	h.SummarizeCase(w, r)
 
-	// Without auth context, the resolveTenant will fail first
-	if w.Code != http.StatusUnauthorized {
-		t.Errorf("expected 401, got %d", w.Code)
+	// Without tenant context, TenantFromContext returns !ok → 403
+	if w.Code != http.StatusForbidden {
+		t.Errorf("expected 403, got %d", w.Code)
 	}
 }
 
@@ -67,8 +67,8 @@ func TestAISummarizeCase_InvalidJSON(t *testing.T) {
 
 	h.SummarizeCase(w, r)
 
-	// Without auth context, the resolveTenant will fail first
-	if w.Code != http.StatusUnauthorized {
-		t.Errorf("expected 401, got %d", w.Code)
+	// Without tenant context, TenantFromContext returns !ok → 403
+	if w.Code != http.StatusForbidden {
+		t.Errorf("expected 403, got %d", w.Code)
 	}
 }

backend/internal/handlers/appointments.go

@@ -121,6 +121,10 @@ func (h *AppointmentHandler) Create(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "title is required")
 		return
 	}
+	if msg := validateStringLength("title", req.Title, maxTitleLen); msg != "" {
+		writeError(w, http.StatusBadRequest, msg)
+		return
+	}
 	if req.StartAt.IsZero() {
 		writeError(w, http.StatusBadRequest, "start_at is required")
 		return
@@ -188,6 +192,10 @@ func (h *AppointmentHandler) Update(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "title is required")
 		return
 	}
+	if msg := validateStringLength("title", req.Title, maxTitleLen); msg != "" {
+		writeError(w, http.StatusBadRequest, msg)
+		return
+	}
 	if req.StartAt.IsZero() {
 		writeError(w, http.StatusBadRequest, "start_at is required")
 		return

backend/internal/handlers/audit_log.go

@@ -0,0 +1,63 @@
+package handlers
+
+import (
+	"net/http"
+	"strconv"
+
+	"github.com/google/uuid"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
+)
+
+type AuditLogHandler struct {
+	svc *services.AuditService
+}
+
+func NewAuditLogHandler(svc *services.AuditService) *AuditLogHandler {
+	return &AuditLogHandler{svc: svc}
+}
+
+func (h *AuditLogHandler) List(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
+		return
+	}
+
+	q := r.URL.Query()
+	page, _ := strconv.Atoi(q.Get("page"))
+	limit, _ := strconv.Atoi(q.Get("limit"))
+
+	filter := services.AuditFilter{
+		EntityType: q.Get("entity_type"),
+		From:       q.Get("from"),
+		To:         q.Get("to"),
+		Page:       page,
+		Limit:      limit,
+	}
+
+	if idStr := q.Get("entity_id"); idStr != "" {
+		if id, err := uuid.Parse(idStr); err == nil {
+			filter.EntityID = &id
+		}
+	}
+	if idStr := q.Get("user_id"); idStr != "" {
+		if id, err := uuid.Parse(idStr); err == nil {
+			filter.UserID = &id
+		}
+	}
+
+	entries, total, err := h.svc.List(r.Context(), tenantID, filter)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to fetch audit log")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"entries": entries,
+		"total":   total,
+		"page":    filter.Page,
+		"limit":   filter.Limit,
+	})
+}

backend/internal/handlers/caldav.go

@@ -27,7 +27,7 @@ func (h *CalDAVHandler) TriggerSync(w http.ResponseWriter, r *http.Request) {
 
 	cfg, err := h.svc.LoadTenantConfig(tenantID)
 	if err != nil {
-		writeError(w, http.StatusBadRequest, err.Error())
+		writeError(w, http.StatusBadRequest, "CalDAV not configured for this tenant")
 		return
 	}
 

backend/internal/handlers/cases.go

@@ -28,18 +28,25 @@ func (h *CaseHandler) List(w http.ResponseWriter, r *http.Request) {
 
 	limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
 	offset, _ := strconv.Atoi(r.URL.Query().Get("offset"))
+	limit, offset = clampPagination(limit, offset)
+
+	search := r.URL.Query().Get("search")
+	if msg := validateStringLength("search", search, maxSearchLen); msg != "" {
+		writeError(w, http.StatusBadRequest, msg)
+		return
+	}
 
 	filter := services.CaseFilter{
 		Status: r.URL.Query().Get("status"),
 		Type:   r.URL.Query().Get("type"),
-		Search: r.URL.Query().Get("search"),
+		Search: search,
 		Limit:  limit,
 		Offset: offset,
 	}
 
 	cases, total, err := h.svc.List(r.Context(), tenantID, filter)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to list cases", err)
 		return
 	}
 
@@ -66,10 +73,18 @@ func (h *CaseHandler) Create(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "case_number and title are required")
 		return
 	}
+	if msg := validateStringLength("case_number", input.CaseNumber, maxCaseNumberLen); msg != "" {
+		writeError(w, http.StatusBadRequest, msg)
+		return
+	}
+	if msg := validateStringLength("title", input.Title, maxTitleLen); msg != "" {
+		writeError(w, http.StatusBadRequest, msg)
+		return
+	}
 
 	c, err := h.svc.Create(r.Context(), tenantID, userID, input)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to create case", err)
 		return
 	}
 
@@ -91,7 +106,7 @@ func (h *CaseHandler) Get(w http.ResponseWriter, r *http.Request) {
 
 	detail, err := h.svc.GetByID(r.Context(), tenantID, caseID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to get case", err)
 		return
 	}
 	if detail == nil {
@@ -121,10 +136,22 @@ func (h *CaseHandler) Update(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "invalid JSON body")
 		return
 	}
+	if input.Title != nil {
+		if msg := validateStringLength("title", *input.Title, maxTitleLen); msg != "" {
+			writeError(w, http.StatusBadRequest, msg)
+			return
+		}
+	}
+	if input.CaseNumber != nil {
+		if msg := validateStringLength("case_number", *input.CaseNumber, maxCaseNumberLen); msg != "" {
+			writeError(w, http.StatusBadRequest, msg)
+			return
+		}
+	}
 
 	updated, err := h.svc.Update(r.Context(), tenantID, caseID, userID, input)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to update case", err)
 		return
 	}
 	if updated == nil {

backend/internal/handlers/dashboard.go

@@ -24,7 +24,7 @@ func (h *DashboardHandler) Get(w http.ResponseWriter, r *http.Request) {
 
 	data, err := h.svc.Get(r.Context(), tenantID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to load dashboard", err)
 		return
 	}
 

backend/internal/handlers/deadlines.go

@@ -4,27 +4,25 @@ import (
 	"encoding/json"
 	"net/http"
 
-	"github.com/jmoiron/sqlx"
-
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
 )
 
 // DeadlineHandlers holds handlers for deadline CRUD endpoints
 type DeadlineHandlers struct {
 	deadlines *services.DeadlineService
-	db        *sqlx.DB
 }
 
 // NewDeadlineHandlers creates deadline handlers
-func NewDeadlineHandlers(ds *services.DeadlineService, db *sqlx.DB) *DeadlineHandlers {
-	return &DeadlineHandlers{deadlines: ds, db: db}
+func NewDeadlineHandlers(ds *services.DeadlineService) *DeadlineHandlers {
+	return &DeadlineHandlers{deadlines: ds}
 }
 
 // Get handles GET /api/deadlines/{deadlineID}
 func (h *DeadlineHandlers) Get(w http.ResponseWriter, r *http.Request) {
-	tenantID, err := resolveTenant(r, h.db)
-	if err != nil {
-		handleTenantError(w, err)
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
 		return
 	}
 
@@ -36,7 +34,7 @@ func (h *DeadlineHandlers) Get(w http.ResponseWriter, r *http.Request) {
 
 	deadline, err := h.deadlines.GetByID(tenantID, deadlineID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, "failed to fetch deadline")
+		internalError(w, "failed to fetch deadline", err)
 		return
 	}
 	if deadline == nil {
@@ -49,15 +47,15 @@ func (h *DeadlineHandlers) Get(w http.ResponseWriter, r *http.Request) {
 
 // ListAll handles GET /api/deadlines
 func (h *DeadlineHandlers) ListAll(w http.ResponseWriter, r *http.Request) {
-	tenantID, err := resolveTenant(r, h.db)
-	if err != nil {
-		handleTenantError(w, err)
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
 		return
 	}
 
 	deadlines, err := h.deadlines.ListAll(tenantID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, "failed to list deadlines")
+		internalError(w, "failed to list deadlines", err)
 		return
 	}
 
@@ -66,9 +64,9 @@ func (h *DeadlineHandlers) ListAll(w http.ResponseWriter, r *http.Request) {
 
 // ListForCase handles GET /api/cases/{caseID}/deadlines
 func (h *DeadlineHandlers) ListForCase(w http.ResponseWriter, r *http.Request) {
-	tenantID, err := resolveTenant(r, h.db)
-	if err != nil {
-		handleTenantError(w, err)
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
 		return
 	}
 
@@ -80,7 +78,7 @@ func (h *DeadlineHandlers) ListForCase(w http.ResponseWriter, r *http.Request) {
 
 	deadlines, err := h.deadlines.ListForCase(tenantID, caseID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, "failed to list deadlines")
+		internalError(w, "failed to list deadlines for case", err)
 		return
 	}
 
@@ -89,9 +87,9 @@ func (h *DeadlineHandlers) ListForCase(w http.ResponseWriter, r *http.Request) {
 
 // Create handles POST /api/cases/{caseID}/deadlines
 func (h *DeadlineHandlers) Create(w http.ResponseWriter, r *http.Request) {
-	tenantID, err := resolveTenant(r, h.db)
-	if err != nil {
-		handleTenantError(w, err)
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
 		return
 	}
 
@@ -112,10 +110,14 @@ func (h *DeadlineHandlers) Create(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "title and due_date are required")
 		return
 	}
+	if msg := validateStringLength("title", input.Title, maxTitleLen); msg != "" {
+		writeError(w, http.StatusBadRequest, msg)
+		return
+	}
 
-	deadline, err := h.deadlines.Create(tenantID, input)
+	deadline, err := h.deadlines.Create(r.Context(), tenantID, input)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, "failed to create deadline")
+		internalError(w, "failed to create deadline", err)
 		return
 	}
 
@@ -124,9 +126,9 @@ func (h *DeadlineHandlers) Create(w http.ResponseWriter, r *http.Request) {
 
 // Update handles PUT /api/deadlines/{deadlineID}
 func (h *DeadlineHandlers) Update(w http.ResponseWriter, r *http.Request) {
-	tenantID, err := resolveTenant(r, h.db)
-	if err != nil {
-		handleTenantError(w, err)
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
 		return
 	}
 
@@ -142,9 +144,9 @@ func (h *DeadlineHandlers) Update(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	deadline, err := h.deadlines.Update(tenantID, deadlineID, input)
+	deadline, err := h.deadlines.Update(r.Context(), tenantID, deadlineID, input)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, "failed to update deadline")
+		internalError(w, "failed to update deadline", err)
 		return
 	}
 	if deadline == nil {
@@ -157,9 +159,9 @@ func (h *DeadlineHandlers) Update(w http.ResponseWriter, r *http.Request) {
 
 // Complete handles PATCH /api/deadlines/{deadlineID}/complete
 func (h *DeadlineHandlers) Complete(w http.ResponseWriter, r *http.Request) {
-	tenantID, err := resolveTenant(r, h.db)
-	if err != nil {
-		handleTenantError(w, err)
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
 		return
 	}
 
@@ -169,9 +171,9 @@ func (h *DeadlineHandlers) Complete(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	deadline, err := h.deadlines.Complete(tenantID, deadlineID)
+	deadline, err := h.deadlines.Complete(r.Context(), tenantID, deadlineID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, "failed to complete deadline")
+		internalError(w, "failed to complete deadline", err)
 		return
 	}
 	if deadline == nil {
@@ -184,9 +186,9 @@ func (h *DeadlineHandlers) Complete(w http.ResponseWriter, r *http.Request) {
 
 // Delete handles DELETE /api/deadlines/{deadlineID}
 func (h *DeadlineHandlers) Delete(w http.ResponseWriter, r *http.Request) {
-	tenantID, err := resolveTenant(r, h.db)
-	if err != nil {
-		handleTenantError(w, err)
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusForbidden, "missing tenant")
 		return
 	}
 
@@ -196,9 +198,8 @@ func (h *DeadlineHandlers) Delete(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	err = h.deadlines.Delete(tenantID, deadlineID)
-	if err != nil {
-		writeError(w, http.StatusNotFound, err.Error())
+	if err := h.deadlines.Delete(r.Context(), tenantID, deadlineID); err != nil {
+		writeError(w, http.StatusNotFound, "deadline not found")
 		return
 	}
 

backend/internal/handlers/determine.go

@@ -0,0 +1,127 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/google/uuid"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
+)
+
+// DetermineHandlers holds handlers for deadline determination endpoints
+type DetermineHandlers struct {
+	determine *services.DetermineService
+	deadlines *services.DeadlineService
+}
+
+// NewDetermineHandlers creates determine handlers
+func NewDetermineHandlers(determine *services.DetermineService, deadlines *services.DeadlineService) *DetermineHandlers {
+	return &DetermineHandlers{determine: determine, deadlines: deadlines}
+}
+
+// GetTimeline handles GET /api/proceeding-types/{code}/timeline
+// Returns the full event tree for a proceeding type (no date calculations)
+func (h *DetermineHandlers) GetTimeline(w http.ResponseWriter, r *http.Request) {
+	code := r.PathValue("code")
+	if code == "" {
+		writeError(w, http.StatusBadRequest, "proceeding type code required")
+		return
+	}
+
+	timeline, pt, err := h.determine.GetTimeline(code)
+	if err != nil {
+		writeError(w, http.StatusNotFound, "proceeding type not found")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"proceeding_type": pt,
+		"timeline":        timeline,
+	})
+}
+
+// Determine handles POST /api/deadlines/determine
+// Calculates the full timeline with cascading dates and conditional logic
+func (h *DetermineHandlers) Determine(w http.ResponseWriter, r *http.Request) {
+	var req services.DetermineRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+
+	if req.ProceedingType == "" || req.TriggerEventDate == "" {
+		writeError(w, http.StatusBadRequest, "proceeding_type and trigger_event_date are required")
+		return
+	}
+
+	resp, err := h.determine.Determine(req)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusOK, resp)
+}
+
+// BatchCreate handles POST /api/cases/{caseID}/deadlines/batch
+// Creates multiple deadlines on a case from determined timeline
+func (h *DetermineHandlers) BatchCreate(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, "caseID")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid case ID")
+		return
+	}
+
+	var req struct {
+		Deadlines []struct {
+			Title           string     `json:"title"`
+			DueDate         string     `json:"due_date"`
+			OriginalDueDate *string    `json:"original_due_date,omitempty"`
+			RuleID          *uuid.UUID `json:"rule_id,omitempty"`
+			RuleCode        *string    `json:"rule_code,omitempty"`
+			Notes           *string    `json:"notes,omitempty"`
+		} `json:"deadlines"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+
+	if len(req.Deadlines) == 0 {
+		writeError(w, http.StatusBadRequest, "at least one deadline is required")
+		return
+	}
+
+	var created int
+	for _, d := range req.Deadlines {
+		if d.Title == "" || d.DueDate == "" {
+			continue
+		}
+		input := services.CreateDeadlineInput{
+			CaseID:  caseID,
+			Title:   d.Title,
+			DueDate: d.DueDate,
+			Source:   "determined",
+			RuleID:  d.RuleID,
+			Notes:   d.Notes,
+		}
+		_, err := h.deadlines.Create(r.Context(), tenantID, input)
+		if err != nil {
+			internalError(w, "failed to create deadline", err)
+			return
+		}
+		created++
+	}
+
+	writeJSON(w, http.StatusCreated, map[string]any{
+		"created": created,
+	})
+}

backend/internal/handlers/documents.go

@@ -36,7 +36,7 @@ func (h *DocumentHandler) ListByCase(w http.ResponseWriter, r *http.Request) {
 
 	docs, err := h.svc.ListByCase(r.Context(), tenantID, caseID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to list documents", err)
 		return
 	}
 
@@ -98,7 +98,7 @@ func (h *DocumentHandler) Upload(w http.ResponseWriter, r *http.Request) {
 			writeError(w, http.StatusNotFound, "case not found")
 			return
 		}
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to upload document", err)
 		return
 	}
 
@@ -121,16 +121,16 @@ func (h *DocumentHandler) Download(w http.ResponseWriter, r *http.Request) {
 	body, contentType, title, err := h.svc.Download(r.Context(), tenantID, docID)
 	if err != nil {
 		if err.Error() == "document not found" || err.Error() == "document has no file" {
-			writeError(w, http.StatusNotFound, err.Error())
+			writeError(w, http.StatusNotFound, "document not found")
 			return
 		}
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to download document", err)
 		return
 	}
 	defer body.Close()
 
 	w.Header().Set("Content-Type", contentType)
-	w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="%s"`, title))
+	w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="%s"`, sanitizeFilename(title)))
 	io.Copy(w, body)
 }
 
@@ -149,7 +149,7 @@ func (h *DocumentHandler) GetMeta(w http.ResponseWriter, r *http.Request) {
 
 	doc, err := h.svc.GetByID(r.Context(), tenantID, docID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to get document metadata", err)
 		return
 	}
 	if doc == nil {

backend/internal/handlers/helpers.go

@@ -2,12 +2,12 @@ package handlers
 
 import (
 	"encoding/json"
+	"log/slog"
 	"net/http"
+	"strings"
+	"unicode/utf8"
 
 	"github.com/google/uuid"
-	"github.com/jmoiron/sqlx"
-
-	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
 )
 
 func writeJSON(w http.ResponseWriter, status int, v any) {
@@ -20,62 +20,9 @@ func writeError(w http.ResponseWriter, status int, msg string) {
 	writeJSON(w, status, map[string]string{"error": msg})
 }
 
-// resolveTenant gets the tenant ID for the authenticated user.
-// Checks X-Tenant-ID header first, then falls back to user's first tenant.
-func resolveTenant(r *http.Request, db *sqlx.DB) (uuid.UUID, error) {
-	userID, ok := auth.UserFromContext(r.Context())
-	if !ok {
-		return uuid.Nil, errUnauthorized
-	}
-
-	// Check header first
-	if headerVal := r.Header.Get("X-Tenant-ID"); headerVal != "" {
-		tenantID, err := uuid.Parse(headerVal)
-		if err != nil {
-			return uuid.Nil, errInvalidTenant
-		}
-		// Verify user has access to this tenant
-		var count int
-		err = db.Get(&count,
-			`SELECT COUNT(*) FROM user_tenants WHERE user_id = $1 AND tenant_id = $2`,
-			userID, tenantID)
-		if err != nil || count == 0 {
-			return uuid.Nil, errTenantAccess
-		}
-		return tenantID, nil
-	}
-
-	// Fall back to user's first tenant
-	var tenantID uuid.UUID
-	err := db.Get(&tenantID,
-		`SELECT tenant_id FROM user_tenants WHERE user_id = $1 ORDER BY created_at LIMIT 1`,
-		userID)
-	if err != nil {
-		return uuid.Nil, errNoTenant
-	}
-	return tenantID, nil
-}
-
-type apiError struct {
-	msg    string
-	status int
-}
-
-func (e *apiError) Error() string { return e.msg }
-
-var (
-	errUnauthorized = &apiError{msg: "unauthorized", status: http.StatusUnauthorized}
-	errInvalidTenant = &apiError{msg: "invalid tenant ID", status: http.StatusBadRequest}
-	errTenantAccess  = &apiError{msg: "no access to tenant", status: http.StatusForbidden}
-	errNoTenant      = &apiError{msg: "no tenant found for user", status: http.StatusBadRequest}
-)
-
-// handleTenantError writes the appropriate error response for tenant resolution errors
-func handleTenantError(w http.ResponseWriter, err error) {
-	if ae, ok := err.(*apiError); ok {
-		writeError(w, ae.status, ae.msg)
-		return
-	}
+// internalError logs the real error and returns a generic message to the client.
+func internalError(w http.ResponseWriter, msg string, err error) {
+	slog.Error(msg, "error", err)
 	writeError(w, http.StatusInternalServerError, "internal error")
 }
 
@@ -88,3 +35,74 @@ func parsePathUUID(r *http.Request, key string) (uuid.UUID, error) {
 func parseUUID(s string) (uuid.UUID, error) {
 	return uuid.Parse(s)
 }
+
+// --- Input validation helpers ---
+
+const (
+	maxTitleLen       = 500
+	maxDescriptionLen = 10000
+	maxCaseNumberLen  = 100
+	maxSearchLen      = 200
+	maxPaginationLimit = 100
+)
+
+// validateStringLength checks if a string exceeds the given max length.
+func validateStringLength(field, value string, maxLen int) string {
+	if utf8.RuneCountInString(value) > maxLen {
+		return field + " exceeds maximum length"
+	}
+	return ""
+}
+
+// clampPagination enforces sane pagination defaults and limits.
+func clampPagination(limit, offset int) (int, int) {
+	if limit <= 0 {
+		limit = 20
+	}
+	if limit > maxPaginationLimit {
+		limit = maxPaginationLimit
+	}
+	if offset < 0 {
+		offset = 0
+	}
+	return limit, offset
+}
+
+// sanitizeFilename removes characters unsafe for Content-Disposition headers.
+func sanitizeFilename(name string) string {
+	// Remove control characters, quotes, and backslashes
+	var b strings.Builder
+	for _, r := range name {
+		if r < 32 || r == '"' || r == '\\' || r == '/' {
+			b.WriteRune('_')
+		} else {
+			b.WriteRune(r)
+		}
+	}
+	return b.String()
+}
+
+// maskSettingsPassword masks the CalDAV password in tenant settings JSON before returning to clients.
+func maskSettingsPassword(settings json.RawMessage) json.RawMessage {
+	if len(settings) == 0 {
+		return settings
+	}
+	var m map[string]json.RawMessage
+	if err := json.Unmarshal(settings, &m); err != nil {
+		return settings
+	}
+	caldavRaw, ok := m["caldav"]
+	if !ok {
+		return settings
+	}
+	var caldav map[string]json.RawMessage
+	if err := json.Unmarshal(caldavRaw, &caldav); err != nil {
+		return settings
+	}
+	if _, ok := caldav["password"]; ok {
+		caldav["password"], _ = json.Marshal("********")
+	}
+	m["caldav"], _ = json.Marshal(caldav)
+	result, _ := json.Marshal(m)
+	return result
+}

backend/internal/handlers/notes.go

@@ -60,6 +60,10 @@ func (h *NoteHandler) Create(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "content is required")
 		return
 	}
+	if msg := validateStringLength("content", input.Content, maxDescriptionLen); msg != "" {
+		writeError(w, http.StatusBadRequest, msg)
+		return
+	}
 
 	var createdBy *uuid.UUID
 	if userID != uuid.Nil {
@@ -100,6 +104,10 @@ func (h *NoteHandler) Update(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "content is required")
 		return
 	}
+	if msg := validateStringLength("content", req.Content, maxDescriptionLen); msg != "" {
+		writeError(w, http.StatusBadRequest, msg)
+		return
+	}
 
 	note, err := h.svc.Update(r.Context(), tenantID, noteID, req.Content)
 	if err != nil {

backend/internal/handlers/notifications.go

@@ -0,0 +1,171 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+	"strconv"
+
+	"github.com/jmoiron/sqlx"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
+)
+
+// NotificationHandler handles notification API endpoints.
+type NotificationHandler struct {
+	svc *services.NotificationService
+	db  *sqlx.DB
+}
+
+// NewNotificationHandler creates a new notification handler.
+func NewNotificationHandler(svc *services.NotificationService, db *sqlx.DB) *NotificationHandler {
+	return &NotificationHandler{svc: svc, db: db}
+}
+
+// List returns paginated notifications for the authenticated user.
+func (h *NotificationHandler) List(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	userID, ok := auth.UserFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+
+	limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
+	offset, _ := strconv.Atoi(r.URL.Query().Get("offset"))
+
+	notifications, total, err := h.svc.ListForUser(r.Context(), tenantID, userID, limit, offset)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to list notifications")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"data":  notifications,
+		"total": total,
+	})
+}
+
+// UnreadCount returns the count of unread notifications.
+func (h *NotificationHandler) UnreadCount(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	userID, ok := auth.UserFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+
+	count, err := h.svc.UnreadCount(r.Context(), tenantID, userID)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to count notifications")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]int{"unread_count": count})
+}
+
+// MarkRead marks a single notification as read.
+func (h *NotificationHandler) MarkRead(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	userID, ok := auth.UserFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+
+	notifID, err := parsePathUUID(r, "id")
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid notification ID")
+		return
+	}
+
+	if err := h.svc.MarkRead(r.Context(), tenantID, userID, notifID); err != nil {
+		writeError(w, http.StatusNotFound, err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
+}
+
+// MarkAllRead marks all notifications as read.
+func (h *NotificationHandler) MarkAllRead(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	userID, ok := auth.UserFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+
+	if err := h.svc.MarkAllRead(r.Context(), tenantID, userID); err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to mark all read")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
+}
+
+// GetPreferences returns notification preferences for the authenticated user.
+func (h *NotificationHandler) GetPreferences(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	userID, ok := auth.UserFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+
+	pref, err := h.svc.GetPreferences(r.Context(), tenantID, userID)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to get preferences")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, pref)
+}
+
+// UpdatePreferences updates notification preferences for the authenticated user.
+func (h *NotificationHandler) UpdatePreferences(w http.ResponseWriter, r *http.Request) {
+	tenantID, ok := auth.TenantFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	userID, ok := auth.UserFromContext(r.Context())
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+
+	var input services.UpdatePreferencesInput
+	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+
+	pref, err := h.svc.UpdatePreferences(r.Context(), tenantID, userID, input)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to update preferences")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, pref)
+}

backend/internal/handlers/parties.go

@@ -34,7 +34,7 @@ func (h *PartyHandler) List(w http.ResponseWriter, r *http.Request) {
 
 	parties, err := h.svc.ListByCase(r.Context(), tenantID, caseID)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to list parties", err)
 		return
 	}
 
@@ -67,13 +67,18 @@ func (h *PartyHandler) Create(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if msg := validateStringLength("name", input.Name, maxTitleLen); msg != "" {
+		writeError(w, http.StatusBadRequest, msg)
+		return
+	}
+
 	party, err := h.svc.Create(r.Context(), tenantID, caseID, userID, input)
 	if err != nil {
 		if err == sql.ErrNoRows {
 			writeError(w, http.StatusNotFound, "case not found")
 			return
 		}
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to create party", err)
 		return
 	}
 
@@ -101,7 +106,7 @@ func (h *PartyHandler) Update(w http.ResponseWriter, r *http.Request) {
 
 	updated, err := h.svc.Update(r.Context(), tenantID, partyID, input)
 	if err != nil {
-		writeError(w, http.StatusInternalServerError, err.Error())
+		internalError(w, "failed to update party", err)
 		return
 	}
 	if updated == nil {

backend/internal/handlers/tenant_handler.go

@@ -2,6 +2,7 @@ package handlers
 
 import (
 	"encoding/json"
+	"log/slog"
 	"net/http"
 
 	"github.com/google/uuid"
@@ -41,7 +42,8 @@ func (h *TenantHandler) CreateTenant(w http.ResponseWriter, r *http.Request) {
 
 	tenant, err := h.svc.Create(r.Context(), userID, req.Name, req.Slug)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to create tenant", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 
@@ -58,10 +60,16 @@ func (h *TenantHandler) ListTenants(w http.ResponseWriter, r *http.Request) {
 
 	tenants, err := h.svc.ListForUser(r.Context(), userID)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to list tenants", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 
+	// Mask CalDAV passwords in tenant settings
+	for i := range tenants {
+		tenants[i].Settings = maskSettingsPassword(tenants[i].Settings)
+	}
+
 	jsonResponse(w, tenants, http.StatusOK)
 }
 
@@ -82,7 +90,8 @@ func (h *TenantHandler) GetTenant(w http.ResponseWriter, r *http.Request) {
 	// Verify user has access to this tenant
 	role, err := h.svc.GetUserRole(r.Context(), userID, tenantID)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to get user role", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 	if role == "" {
@@ -92,7 +101,8 @@ func (h *TenantHandler) GetTenant(w http.ResponseWriter, r *http.Request) {
 
 	tenant, err := h.svc.GetByID(r.Context(), tenantID)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to get tenant", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 	if tenant == nil {
@@ -100,6 +110,9 @@ func (h *TenantHandler) GetTenant(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Mask CalDAV password before returning
+	tenant.Settings = maskSettingsPassword(tenant.Settings)
+
 	jsonResponse(w, tenant, http.StatusOK)
 }
 
@@ -120,7 +133,8 @@ func (h *TenantHandler) InviteUser(w http.ResponseWriter, r *http.Request) {
 	// Only owners and partners can invite
 	role, err := h.svc.GetUserRole(r.Context(), userID, tenantID)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to get user role", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 	if role != "owner" && role != "partner" {
@@ -155,7 +169,8 @@ func (h *TenantHandler) InviteUser(w http.ResponseWriter, r *http.Request) {
 
 	ut, err := h.svc.InviteByEmail(r.Context(), tenantID, req.Email, req.Role)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusBadRequest)
+		// These are user-facing validation errors (user not found, already member)
+		jsonError(w, "failed to invite user", http.StatusBadRequest)
 		return
 	}
 
@@ -185,7 +200,8 @@ func (h *TenantHandler) RemoveMember(w http.ResponseWriter, r *http.Request) {
 	// Only owners and partners can remove members (or user removing themselves)
 	role, err := h.svc.GetUserRole(r.Context(), userID, tenantID)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to get user role", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 	if role != "owner" && role != "partner" && userID != memberID {
@@ -194,7 +210,8 @@ func (h *TenantHandler) RemoveMember(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := h.svc.RemoveMember(r.Context(), tenantID, memberID); err != nil {
-		jsonError(w, err.Error(), http.StatusBadRequest)
+		// These are user-facing validation errors (not a member, last owner, etc.)
+		jsonError(w, "failed to remove member", http.StatusBadRequest)
 		return
 	}
 
@@ -218,7 +235,8 @@ func (h *TenantHandler) UpdateSettings(w http.ResponseWriter, r *http.Request) {
 	// Only owners and partners can update settings
 	role, err := h.svc.GetUserRole(r.Context(), userID, tenantID)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to get user role", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 	if role != "owner" && role != "partner" {
@@ -234,10 +252,14 @@ func (h *TenantHandler) UpdateSettings(w http.ResponseWriter, r *http.Request) {
 
 	tenant, err := h.svc.UpdateSettings(r.Context(), tenantID, settings)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to update settings", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 
+	// Mask CalDAV password before returning
+	tenant.Settings = maskSettingsPassword(tenant.Settings)
+
 	jsonResponse(w, tenant, http.StatusOK)
 }
 
@@ -258,7 +280,8 @@ func (h *TenantHandler) ListMembers(w http.ResponseWriter, r *http.Request) {
 	// Verify user has access
 	role, err := h.svc.GetUserRole(r.Context(), userID, tenantID)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to get user role", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 	if role == "" {
@@ -268,7 +291,8 @@ func (h *TenantHandler) ListMembers(w http.ResponseWriter, r *http.Request) {
 
 	members, err := h.svc.ListMembers(r.Context(), tenantID)
 	if err != nil {
-		jsonError(w, err.Error(), http.StatusInternalServerError)
+		slog.Error("failed to list members", "error", err)
+		jsonError(w, "internal error", http.StatusInternalServerError)
 		return
 	}
 

backend/internal/integration_test.go

@@ -46,7 +46,7 @@ func testServer(t *testing.T) (http.Handler, func()) {
 	}
 
 	authMW := auth.NewMiddleware(jwtSecret, database)
-	handler := router.New(database, authMW, cfg, nil)
+	handler := router.New(database, authMW, cfg, nil, nil)
 
 	return handler, func() { database.Close() }
 }

backend/internal/middleware/security.go

@@ -0,0 +1,49 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+)
+
+// SecurityHeaders adds standard security headers to all responses.
+func SecurityHeaders(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("X-Frame-Options", "DENY")
+		w.Header().Set("X-Content-Type-Options", "nosniff")
+		w.Header().Set("X-XSS-Protection", "1; mode=block")
+		w.Header().Set("Strict-Transport-Security", "max-age=31536000; includeSubDomains")
+		w.Header().Set("Referrer-Policy", "strict-origin-when-cross-origin")
+		next.ServeHTTP(w, r)
+	})
+}
+
+// CORS returns middleware that restricts cross-origin requests to the given origin.
+// If allowedOrigin is empty, CORS headers are not set (same-origin only).
+func CORS(allowedOrigin string) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			origin := r.Header.Get("Origin")
+
+			if allowedOrigin != "" && origin != "" && matchOrigin(origin, allowedOrigin) {
+				w.Header().Set("Access-Control-Allow-Origin", allowedOrigin)
+				w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, PATCH, DELETE, OPTIONS")
+				w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization, X-Tenant-ID")
+				w.Header().Set("Access-Control-Max-Age", "86400")
+				w.Header().Set("Vary", "Origin")
+			}
+
+			// Handle preflight
+			if r.Method == http.MethodOptions {
+				w.WriteHeader(http.StatusNoContent)
+				return
+			}
+
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+// matchOrigin checks if the request origin matches the allowed origin.
+func matchOrigin(origin, allowed string) bool {
+	return strings.EqualFold(strings.TrimRight(origin, "/"), strings.TrimRight(allowed, "/"))
+}

backend/internal/models/audit_log.go

@@ -0,0 +1,22 @@
+package models
+
+import (
+	"encoding/json"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+type AuditLog struct {
+	ID         int64            `db:"id" json:"id"`
+	TenantID   uuid.UUID        `db:"tenant_id" json:"tenant_id"`
+	UserID     *uuid.UUID       `db:"user_id" json:"user_id,omitempty"`
+	Action     string           `db:"action" json:"action"`
+	EntityType string           `db:"entity_type" json:"entity_type"`
+	EntityID   *uuid.UUID       `db:"entity_id" json:"entity_id,omitempty"`
+	OldValues  *json.RawMessage `db:"old_values" json:"old_values,omitempty"`
+	NewValues  *json.RawMessage `db:"new_values" json:"new_values,omitempty"`
+	IPAddress  *string          `db:"ip_address" json:"ip_address,omitempty"`
+	UserAgent  *string          `db:"user_agent" json:"user_agent,omitempty"`
+	CreatedAt  time.Time        `db:"created_at" json:"created_at"`
+}

backend/internal/models/deadline_rule.go

@@ -26,6 +26,8 @@ type DeadlineRule struct {
 	AltDurationValue *int       `db:"alt_duration_value" json:"alt_duration_value,omitempty"`
 	AltDurationUnit  *string    `db:"alt_duration_unit" json:"alt_duration_unit,omitempty"`
 	AltRuleCode      *string    `db:"alt_rule_code" json:"alt_rule_code,omitempty"`
+	IsSpawn          bool       `db:"is_spawn" json:"is_spawn"`
+	SpawnLabel       *string    `db:"spawn_label" json:"spawn_label,omitempty"`
 	IsActive         bool       `db:"is_active" json:"is_active"`
 	CreatedAt        time.Time  `db:"created_at" json:"created_at"`
 	UpdatedAt        time.Time  `db:"updated_at" json:"updated_at"`

backend/internal/models/notification.go

@@ -0,0 +1,32 @@
+package models
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/lib/pq"
+)
+
+type Notification 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"`
+	Type       string     `db:"type" json:"type"`
+	EntityType *string    `db:"entity_type" json:"entity_type,omitempty"`
+	EntityID   *uuid.UUID `db:"entity_id" json:"entity_id,omitempty"`
+	Title      string     `db:"title" json:"title"`
+	Body       *string    `db:"body" json:"body,omitempty"`
+	SentAt     *time.Time `db:"sent_at" json:"sent_at,omitempty"`
+	ReadAt     *time.Time `db:"read_at" json:"read_at,omitempty"`
+	CreatedAt  time.Time  `db:"created_at" json:"created_at"`
+}
+
+type NotificationPreferences struct {
+	UserID              uuid.UUID     `db:"user_id" json:"user_id"`
+	TenantID            uuid.UUID     `db:"tenant_id" json:"tenant_id"`
+	DeadlineReminderDays pq.Int64Array `db:"deadline_reminder_days" json:"deadline_reminder_days"`
+	EmailEnabled        bool          `db:"email_enabled" json:"email_enabled"`
+	DailyDigest         bool          `db:"daily_digest" json:"daily_digest"`
+	CreatedAt           time.Time     `db:"created_at" json:"created_at"`
+	UpdatedAt           time.Time     `db:"updated_at" json:"updated_at"`
+}

backend/internal/router/router.go

@@ -15,43 +15,53 @@ import (
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
 )
 
-func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *services.CalDAVService) 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
-	tenantSvc := services.NewTenantService(db)
-	caseSvc := services.NewCaseService(db)
-	partySvc := services.NewPartyService(db)
-	appointmentSvc := services.NewAppointmentService(db)
+	auditSvc := services.NewAuditService(db)
+	tenantSvc := services.NewTenantService(db, auditSvc)
+	caseSvc := services.NewCaseService(db, auditSvc)
+	partySvc := services.NewPartyService(db, auditSvc)
+	appointmentSvc := services.NewAppointmentService(db, auditSvc)
 	holidaySvc := services.NewHolidayService(db)
-	deadlineSvc := services.NewDeadlineService(db)
+	deadlineSvc := services.NewDeadlineService(db, auditSvc)
 	deadlineRuleSvc := services.NewDeadlineRuleService(db)
 	calculator := services.NewDeadlineCalculator(holidaySvc)
+	determineSvc := services.NewDetermineService(db, calculator)
 	storageCli := services.NewStorageClient(cfg.SupabaseURL, cfg.SupabaseServiceKey)
-	documentSvc := services.NewDocumentService(db, storageCli)
+	documentSvc := services.NewDocumentService(db, storageCli, auditSvc)
 	assignmentSvc := services.NewCaseAssignmentService(db)
 
 	// AI service (optional — only if API key is configured)
 	var aiH *handlers.AIHandler
 	if cfg.AnthropicAPIKey != "" {
 		aiSvc := services.NewAIService(cfg.AnthropicAPIKey, db)
-		aiH = handlers.NewAIHandler(aiSvc, db)
+		aiH = handlers.NewAIHandler(aiSvc)
 	}
 
 	// Middleware
 	tenantResolver := auth.NewTenantResolver(tenantSvc)
 
-	noteSvc := services.NewNoteService(db)
+	noteSvc := services.NewNoteService(db, auditSvc)
 	dashboardSvc := services.NewDashboardService(db)
 
+	// Notification handler (optional — nil in tests)
+	var notifH *handlers.NotificationHandler
+	if notifSvc != nil {
+		notifH = handlers.NewNotificationHandler(notifSvc, db)
+	}
+
 	// Handlers
+	auditH := handlers.NewAuditLogHandler(auditSvc)
 	tenantH := handlers.NewTenantHandler(tenantSvc)
 	caseH := handlers.NewCaseHandler(caseSvc)
 	partyH := handlers.NewPartyHandler(partySvc)
 	apptH := handlers.NewAppointmentHandler(appointmentSvc)
-	deadlineH := handlers.NewDeadlineHandlers(deadlineSvc, db)
+	deadlineH := handlers.NewDeadlineHandlers(deadlineSvc)
 	ruleH := handlers.NewDeadlineRuleHandlers(deadlineRuleSvc)
 	calcH := handlers.NewCalculateHandlers(calculator, deadlineRuleSvc)
+	determineH := handlers.NewDetermineHandlers(determineSvc, deadlineSvc)
 	dashboardH := handlers.NewDashboardHandler(dashboardSvc)
 	noteH := handlers.NewNoteHandler(noteSvc)
 	eventH := handlers.NewCaseEventHandler(db)
@@ -98,7 +108,7 @@ 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
@@ -124,6 +134,11 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	// Deadline calculator — all can use
 	scoped.HandleFunc("POST /api/deadlines/calculate", calcH.Calculate)
 
+	// Deadline determination — full timeline calculation with conditions
+	scoped.HandleFunc("GET /api/proceeding-types/{code}/timeline", determineH.GetTimeline)
+	scoped.HandleFunc("POST /api/deadlines/determine", determineH.Determine)
+	scoped.HandleFunc("POST /api/cases/{caseID}/deadlines/batch", perm(auth.PermManageDeadlines, determineH.BatchCreate))
+
 	// Appointments — all can manage (PermManageAppointments granted to all)
 	scoped.HandleFunc("GET /api/appointments/{id}", apptH.Get)
 	scoped.HandleFunc("GET /api/appointments", apptH.List)
@@ -148,12 +163,15 @@ 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)
+
 	// 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 {
@@ -162,6 +180,16 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 		scoped.HandleFunc("POST /api/ai/summarize-case", perm(auth.PermAIExtraction, aiLimiter.LimitFunc(aiH.SummarizeCase)))
 	}
 
+	// Notifications
+	if notifH != nil {
+		scoped.HandleFunc("GET /api/notifications", notifH.List)
+		scoped.HandleFunc("GET /api/notifications/unread-count", notifH.UnreadCount)
+		scoped.HandleFunc("PATCH /api/notifications/{id}/read", notifH.MarkRead)
+		scoped.HandleFunc("PATCH /api/notifications/read-all", notifH.MarkAllRead)
+		scoped.HandleFunc("GET /api/notification-preferences", notifH.GetPreferences)
+		scoped.HandleFunc("PUT /api/notification-preferences", notifH.UpdatePreferences)
+	}
+
 	// CalDAV sync endpoints — settings permission required
 	if calDAVSvc != nil {
 		calDAVH := handlers.NewCalDAVHandler(calDAVSvc)
@@ -174,14 +202,20 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 
 	mux.Handle("/api/", authMW.RequireAuth(api))
 
-	return requestLogger(mux)
+	// Apply security middleware stack: CORS -> Security Headers -> Request Logger -> Routes
+	var handler http.Handler = mux
+	handler = requestLogger(handler)
+	handler = middleware.SecurityHeaders(handler)
+	handler = middleware.CORS(cfg.FrontendOrigin)(handler)
+
+	return handler
 }
 
 func handleHealth(db *sqlx.DB) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if err := db.Ping(); err != nil {
 			w.WriteHeader(http.StatusServiceUnavailable)
-			json.NewEncoder(w).Encode(map[string]string{"status": "error", "error": err.Error()})
+			json.NewEncoder(w).Encode(map[string]string{"status": "error"})
 			return
 		}
 		w.Header().Set("Content-Type", "application/json")
@@ -219,4 +253,3 @@ func requestLogger(next http.Handler) http.Handler {
 		)
 	})
 }
-

backend/internal/services/appointment_service.go

@@ -12,11 +12,12 @@ import (
 )
 
 type AppointmentService struct {
-	db *sqlx.DB
+	db    *sqlx.DB
+	audit *AuditService
 }
 
-func NewAppointmentService(db *sqlx.DB) *AppointmentService {
-	return &AppointmentService{db: db}
+func NewAppointmentService(db *sqlx.DB, audit *AuditService) *AppointmentService {
+	return &AppointmentService{db: db, audit: audit}
 }
 
 type AppointmentFilter struct {
@@ -86,6 +87,7 @@ func (s *AppointmentService) Create(ctx context.Context, a *models.Appointment)
 	if err != nil {
 		return fmt.Errorf("creating appointment: %w", err)
 	}
+	s.audit.Log(ctx, "create", "appointment", &a.ID, nil, a)
 	return nil
 }
 
@@ -116,6 +118,7 @@ func (s *AppointmentService) Update(ctx context.Context, a *models.Appointment)
 	if rows == 0 {
 		return fmt.Errorf("appointment not found")
 	}
+	s.audit.Log(ctx, "update", "appointment", &a.ID, nil, a)
 	return nil
 }
 
@@ -131,5 +134,6 @@ func (s *AppointmentService) Delete(ctx context.Context, tenantID, id uuid.UUID)
 	if rows == 0 {
 		return fmt.Errorf("appointment not found")
 	}
+	s.audit.Log(ctx, "delete", "appointment", &id, nil, nil)
 	return nil
 }

backend/internal/services/audit_service.go

@@ -0,0 +1,141 @@
+package services
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+
+	"github.com/google/uuid"
+	"github.com/jmoiron/sqlx"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/models"
+)
+
+type AuditService struct {
+	db *sqlx.DB
+}
+
+func NewAuditService(db *sqlx.DB) *AuditService {
+	return &AuditService{db: db}
+}
+
+// Log records an audit entry. It extracts tenant, user, IP, and user-agent from context.
+// Errors are logged but not returned — audit logging must not break business operations.
+func (s *AuditService) Log(ctx context.Context, action, entityType string, entityID *uuid.UUID, oldValues, newValues any) {
+	tenantID, ok := auth.TenantFromContext(ctx)
+	if !ok {
+		slog.Warn("audit: missing tenant_id in context", "action", action, "entity_type", entityType)
+		return
+	}
+
+	var userID *uuid.UUID
+	if uid, ok := auth.UserFromContext(ctx); ok {
+		userID = &uid
+	}
+
+	var oldJSON, newJSON *json.RawMessage
+	if oldValues != nil {
+		if b, err := json.Marshal(oldValues); err == nil {
+			raw := json.RawMessage(b)
+			oldJSON = &raw
+		}
+	}
+	if newValues != nil {
+		if b, err := json.Marshal(newValues); err == nil {
+			raw := json.RawMessage(b)
+			newJSON = &raw
+		}
+	}
+
+	ip := auth.IPFromContext(ctx)
+	ua := auth.UserAgentFromContext(ctx)
+
+	_, err := s.db.ExecContext(ctx,
+		`INSERT INTO audit_log (tenant_id, user_id, action, entity_type, entity_id, old_values, new_values, ip_address, user_agent)
+		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)`,
+		tenantID, userID, action, entityType, entityID, oldJSON, newJSON, ip, ua)
+	if err != nil {
+		slog.Error("audit: failed to write log entry",
+			"error", err,
+			"action", action,
+			"entity_type", entityType,
+			"entity_id", entityID,
+		)
+	}
+}
+
+// AuditFilter holds query parameters for listing audit log entries.
+type AuditFilter struct {
+	EntityType string
+	EntityID   *uuid.UUID
+	UserID     *uuid.UUID
+	From       string // RFC3339 date
+	To         string // RFC3339 date
+	Page       int
+	Limit      int
+}
+
+// List returns paginated audit log entries for a tenant.
+func (s *AuditService) List(ctx context.Context, tenantID uuid.UUID, filter AuditFilter) ([]models.AuditLog, int, error) {
+	if filter.Limit <= 0 {
+		filter.Limit = 50
+	}
+	if filter.Limit > 200 {
+		filter.Limit = 200
+	}
+	if filter.Page <= 0 {
+		filter.Page = 1
+	}
+	offset := (filter.Page - 1) * filter.Limit
+
+	where := "WHERE tenant_id = $1"
+	args := []any{tenantID}
+	argIdx := 2
+
+	if filter.EntityType != "" {
+		where += fmt.Sprintf(" AND entity_type = $%d", argIdx)
+		args = append(args, filter.EntityType)
+		argIdx++
+	}
+	if filter.EntityID != nil {
+		where += fmt.Sprintf(" AND entity_id = $%d", argIdx)
+		args = append(args, *filter.EntityID)
+		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 created_at >= $%d", argIdx)
+		args = append(args, filter.From)
+		argIdx++
+	}
+	if filter.To != "" {
+		where += fmt.Sprintf(" AND created_at <= $%d", argIdx)
+		args = append(args, filter.To)
+		argIdx++
+	}
+
+	var total int
+	if err := s.db.GetContext(ctx, &total, "SELECT COUNT(*) FROM audit_log "+where, args...); err != nil {
+		return nil, 0, fmt.Errorf("counting audit entries: %w", err)
+	}
+
+	query := fmt.Sprintf("SELECT * FROM audit_log %s ORDER BY created_at DESC LIMIT $%d OFFSET $%d",
+		where, argIdx, argIdx+1)
+	args = append(args, filter.Limit, offset)
+
+	var entries []models.AuditLog
+	if err := s.db.SelectContext(ctx, &entries, query, args...); err != nil {
+		return nil, 0, fmt.Errorf("listing audit entries: %w", err)
+	}
+	if entries == nil {
+		entries = []models.AuditLog{}
+	}
+
+	return entries, total, nil
+}

backend/internal/services/case_service.go

@@ -13,11 +13,12 @@ import (
 )
 
 type CaseService struct {
-	db *sqlx.DB
+	db    *sqlx.DB
+	audit *AuditService
 }
 
-func NewCaseService(db *sqlx.DB) *CaseService {
-	return &CaseService{db: db}
+func NewCaseService(db *sqlx.DB, audit *AuditService) *CaseService {
+	return &CaseService{db: db, audit: audit}
 }
 
 type CaseFilter struct {
@@ -162,6 +163,9 @@ func (s *CaseService) Create(ctx context.Context, tenantID uuid.UUID, userID uui
 	if err := s.db.GetContext(ctx, &c, "SELECT * FROM cases WHERE id = $1", id); err != nil {
 		return nil, fmt.Errorf("fetching created case: %w", err)
 	}
+
+	s.audit.Log(ctx, "create", "case", &id, nil, c)
+
 	return &c, nil
 }
 
@@ -239,6 +243,9 @@ func (s *CaseService) Update(ctx context.Context, tenantID, caseID uuid.UUID, us
 	if err := s.db.GetContext(ctx, &updated, "SELECT * FROM cases WHERE id = $1", caseID); err != nil {
 		return nil, fmt.Errorf("fetching updated case: %w", err)
 	}
+
+	s.audit.Log(ctx, "update", "case", &caseID, current, updated)
+
 	return &updated, nil
 }
 
@@ -254,6 +261,7 @@ func (s *CaseService) Delete(ctx context.Context, tenantID, caseID uuid.UUID, us
 		return sql.ErrNoRows
 	}
 	createEvent(ctx, s.db, tenantID, caseID, userID, "case_archived", "Case archived", nil)
+	s.audit.Log(ctx, "delete", "case", &caseID, map[string]string{"status": "active"}, map[string]string{"status": "archived"})
 	return nil
 }
 

backend/internal/services/deadline_rule_service.go

@@ -8,6 +8,12 @@ import (
 	"mgit.msbls.de/m/KanzlAI-mGMT/internal/models"
 )
 
+const ruleColumns = `id, proceeding_type_id, parent_id, code, name, description,
+	primary_party, event_type, is_mandatory, duration_value, duration_unit,
+	timing, rule_code, deadline_notes, sequence_order, condition_rule_id,
+	alt_duration_value, alt_duration_unit, alt_rule_code,
+	is_spawn, spawn_label, is_active, created_at, updated_at`
+
 // DeadlineRuleService handles deadline rule queries
 type DeadlineRuleService struct {
 	db *sqlx.DB
@@ -25,21 +31,13 @@ func (s *DeadlineRuleService) List(proceedingTypeID *int) ([]models.DeadlineRule
 
 	if proceedingTypeID != nil {
 		err = s.db.Select(&rules,
-			`SELECT id, proceeding_type_id, parent_id, code, name, description,
-			        primary_party, event_type, is_mandatory, duration_value, duration_unit,
-			        timing, rule_code, deadline_notes, sequence_order, condition_rule_id,
-			        alt_duration_value, alt_duration_unit, alt_rule_code, is_active,
-			        created_at, updated_at
+			`SELECT `+ruleColumns+`
 			 FROM deadline_rules
 			 WHERE proceeding_type_id = $1 AND is_active = true
 			 ORDER BY sequence_order`, *proceedingTypeID)
 	} else {
 		err = s.db.Select(&rules,
-			`SELECT id, proceeding_type_id, parent_id, code, name, description,
-			        primary_party, event_type, is_mandatory, duration_value, duration_unit,
-			        timing, rule_code, deadline_notes, sequence_order, condition_rule_id,
-			        alt_duration_value, alt_duration_unit, alt_rule_code, is_active,
-			        created_at, updated_at
+			`SELECT `+ruleColumns+`
 			 FROM deadline_rules
 			 WHERE is_active = true
 			 ORDER BY proceeding_type_id, sequence_order`)
@@ -72,11 +70,7 @@ func (s *DeadlineRuleService) GetRuleTree(proceedingTypeCode string) ([]RuleTree
 	// Get all rules for this proceeding type
 	var rules []models.DeadlineRule
 	err = s.db.Select(&rules,
-		`SELECT id, proceeding_type_id, parent_id, code, name, description,
-		        primary_party, event_type, is_mandatory, duration_value, duration_unit,
-		        timing, rule_code, deadline_notes, sequence_order, condition_rule_id,
-		        alt_duration_value, alt_duration_unit, alt_rule_code, is_active,
-		        created_at, updated_at
+		`SELECT `+ruleColumns+`
 		 FROM deadline_rules
 		 WHERE proceeding_type_id = $1 AND is_active = true
 		 ORDER BY sequence_order`, pt.ID)
@@ -87,6 +81,36 @@ func (s *DeadlineRuleService) GetRuleTree(proceedingTypeCode string) ([]RuleTree
 	return buildTree(rules), nil
 }
 
+// GetFullTimeline returns the full event tree for a proceeding type using a recursive CTE.
+// Unlike GetRuleTree, this follows parent_id across proceeding types (includes cross-type spawns).
+func (s *DeadlineRuleService) GetFullTimeline(proceedingTypeCode string) ([]models.DeadlineRule, *models.ProceedingType, error) {
+	var pt models.ProceedingType
+	err := s.db.Get(&pt,
+		`SELECT id, code, name, description, jurisdiction, default_color, sort_order, is_active
+		 FROM proceeding_types
+		 WHERE code = $1 AND is_active = true`, proceedingTypeCode)
+	if err != nil {
+		return nil, nil, fmt.Errorf("resolving proceeding type %q: %w", proceedingTypeCode, err)
+	}
+
+	var rules []models.DeadlineRule
+	err = s.db.Select(&rules, `
+		WITH RECURSIVE tree AS (
+			SELECT * FROM deadline_rules
+			WHERE proceeding_type_id = $1 AND parent_id IS NULL AND is_active = true
+			UNION ALL
+			SELECT dr.* FROM deadline_rules dr
+			JOIN tree t ON dr.parent_id = t.id
+			WHERE dr.is_active = true
+		)
+		SELECT `+ruleColumns+` FROM tree ORDER BY sequence_order`, pt.ID)
+	if err != nil {
+		return nil, nil, fmt.Errorf("fetching timeline for type %q: %w", proceedingTypeCode, err)
+	}
+
+	return rules, &pt, nil
+}
+
 // GetByIDs returns deadline rules by their IDs
 func (s *DeadlineRuleService) GetByIDs(ids []string) ([]models.DeadlineRule, error) {
 	if len(ids) == 0 {
@@ -94,11 +118,7 @@ func (s *DeadlineRuleService) GetByIDs(ids []string) ([]models.DeadlineRule, err
 	}
 
 	query, args, err := sqlx.In(
-		`SELECT id, proceeding_type_id, parent_id, code, name, description,
-		        primary_party, event_type, is_mandatory, duration_value, duration_unit,
-		        timing, rule_code, deadline_notes, sequence_order, condition_rule_id,
-		        alt_duration_value, alt_duration_unit, alt_rule_code, is_active,
-		        created_at, updated_at
+		`SELECT `+ruleColumns+`
 		 FROM deadline_rules
 		 WHERE id IN (?) AND is_active = true
 		 ORDER BY sequence_order`, ids)
@@ -119,11 +139,7 @@ func (s *DeadlineRuleService) GetByIDs(ids []string) ([]models.DeadlineRule, err
 func (s *DeadlineRuleService) GetRulesForProceedingType(proceedingTypeID int) ([]models.DeadlineRule, error) {
 	var rules []models.DeadlineRule
 	err := s.db.Select(&rules,
-		`SELECT id, proceeding_type_id, parent_id, code, name, description,
-		        primary_party, event_type, is_mandatory, duration_value, duration_unit,
-		        timing, rule_code, deadline_notes, sequence_order, condition_rule_id,
-		        alt_duration_value, alt_duration_unit, alt_rule_code, is_active,
-		        created_at, updated_at
+		`SELECT `+ruleColumns+`
 		 FROM deadline_rules
 		 WHERE proceeding_type_id = $1 AND is_active = true
 		 ORDER BY sequence_order`, proceedingTypeID)

backend/internal/services/deadline_service.go

@@ -1,6 +1,7 @@
 package services
 
 import (
+	"context"
 	"database/sql"
 	"fmt"
 	"time"
@@ -13,12 +14,13 @@ import (
 
 // DeadlineService handles CRUD operations for case deadlines
 type DeadlineService struct {
-	db *sqlx.DB
+	db    *sqlx.DB
+	audit *AuditService
 }
 
 // NewDeadlineService creates a new deadline service
-func NewDeadlineService(db *sqlx.DB) *DeadlineService {
-	return &DeadlineService{db: db}
+func NewDeadlineService(db *sqlx.DB, audit *AuditService) *DeadlineService {
+	return &DeadlineService{db: db, audit: audit}
 }
 
 // ListAll returns all deadlines for a tenant, ordered by due_date
@@ -87,7 +89,7 @@ type CreateDeadlineInput struct {
 }
 
 // Create inserts a new deadline
-func (s *DeadlineService) Create(tenantID uuid.UUID, input CreateDeadlineInput) (*models.Deadline, error) {
+func (s *DeadlineService) Create(ctx context.Context, tenantID uuid.UUID, input CreateDeadlineInput) (*models.Deadline, error) {
 	id := uuid.New()
 	source := input.Source
 	if source == "" {
@@ -108,6 +110,7 @@ func (s *DeadlineService) Create(tenantID uuid.UUID, input CreateDeadlineInput)
 	if err != nil {
 		return nil, fmt.Errorf("creating deadline: %w", err)
 	}
+	s.audit.Log(ctx, "create", "deadline", &id, nil, d)
 	return &d, nil
 }
 
@@ -123,7 +126,7 @@ type UpdateDeadlineInput struct {
 }
 
 // Update modifies an existing deadline
-func (s *DeadlineService) Update(tenantID, deadlineID uuid.UUID, input UpdateDeadlineInput) (*models.Deadline, error) {
+func (s *DeadlineService) Update(ctx context.Context, tenantID, deadlineID uuid.UUID, input UpdateDeadlineInput) (*models.Deadline, error) {
 	// First check it exists and belongs to tenant
 	existing, err := s.GetByID(tenantID, deadlineID)
 	if err != nil {
@@ -154,11 +157,12 @@ func (s *DeadlineService) Update(tenantID, deadlineID uuid.UUID, input UpdateDea
 	if err != nil {
 		return nil, fmt.Errorf("updating deadline: %w", err)
 	}
+	s.audit.Log(ctx, "update", "deadline", &deadlineID, existing, d)
 	return &d, nil
 }
 
 // Complete marks a deadline as completed
-func (s *DeadlineService) Complete(tenantID, deadlineID uuid.UUID) (*models.Deadline, error) {
+func (s *DeadlineService) Complete(ctx context.Context, tenantID, deadlineID uuid.UUID) (*models.Deadline, error) {
 	query := `UPDATE deadlines SET
 	            status = 'completed',
 	            completed_at = $1,
@@ -176,11 +180,12 @@ func (s *DeadlineService) Complete(tenantID, deadlineID uuid.UUID) (*models.Dead
 		}
 		return nil, fmt.Errorf("completing deadline: %w", err)
 	}
+	s.audit.Log(ctx, "update", "deadline", &deadlineID, map[string]string{"status": "pending"}, map[string]string{"status": "completed"})
 	return &d, nil
 }
 
 // Delete removes a deadline
-func (s *DeadlineService) Delete(tenantID, deadlineID uuid.UUID) error {
+func (s *DeadlineService) Delete(ctx context.Context, tenantID, deadlineID uuid.UUID) error {
 	query := `DELETE FROM deadlines WHERE id = $1 AND tenant_id = $2`
 	result, err := s.db.Exec(query, deadlineID, tenantID)
 	if err != nil {
@@ -193,5 +198,6 @@ func (s *DeadlineService) Delete(tenantID, deadlineID uuid.UUID) error {
 	if rows == 0 {
 		return fmt.Errorf("deadline not found")
 	}
+	s.audit.Log(ctx, "delete", "deadline", &deadlineID, nil, nil)
 	return nil
 }

backend/internal/services/determine_service.go

@@ -0,0 +1,236 @@
+package services
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/jmoiron/sqlx"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/models"
+)
+
+// DetermineService handles event-driven deadline determination.
+// It walks the proceeding event tree and calculates cascading dates.
+type DetermineService struct {
+	rules      *DeadlineRuleService
+	calculator *DeadlineCalculator
+}
+
+// NewDetermineService creates a new determine service
+func NewDetermineService(db *sqlx.DB, calculator *DeadlineCalculator) *DetermineService {
+	return &DetermineService{
+		rules:      NewDeadlineRuleService(db),
+		calculator: calculator,
+	}
+}
+
+// TimelineEvent represents a calculated event in the proceeding timeline
+type TimelineEvent struct {
+	ID               string          `json:"id"`
+	Code             string          `json:"code,omitempty"`
+	Name             string          `json:"name"`
+	Description      string          `json:"description,omitempty"`
+	PrimaryParty     string          `json:"primary_party,omitempty"`
+	EventType        string          `json:"event_type,omitempty"`
+	IsMandatory      bool            `json:"is_mandatory"`
+	DurationValue    int             `json:"duration_value"`
+	DurationUnit     string          `json:"duration_unit"`
+	RuleCode         string          `json:"rule_code,omitempty"`
+	DeadlineNotes    string          `json:"deadline_notes,omitempty"`
+	IsSpawn          bool            `json:"is_spawn"`
+	SpawnLabel       string          `json:"spawn_label,omitempty"`
+	HasCondition     bool            `json:"has_condition"`
+	ConditionRuleID  string          `json:"condition_rule_id,omitempty"`
+	AltRuleCode      string          `json:"alt_rule_code,omitempty"`
+	AltDurationValue *int            `json:"alt_duration_value,omitempty"`
+	AltDurationUnit  string          `json:"alt_duration_unit,omitempty"`
+	Date             string          `json:"date,omitempty"`
+	OriginalDate     string          `json:"original_date,omitempty"`
+	WasAdjusted      bool            `json:"was_adjusted"`
+	Children         []TimelineEvent `json:"children,omitempty"`
+}
+
+// DetermineRequest is the input for POST /api/deadlines/determine
+type DetermineRequest struct {
+	ProceedingType   string          `json:"proceeding_type"`
+	TriggerEventDate string          `json:"trigger_event_date"`
+	Conditions       map[string]bool `json:"conditions"`
+}
+
+// DetermineResponse is the output of the determine endpoint
+type DetermineResponse struct {
+	ProceedingType  string          `json:"proceeding_type"`
+	ProceedingName  string          `json:"proceeding_name"`
+	ProceedingColor string          `json:"proceeding_color"`
+	TriggerDate     string          `json:"trigger_event_date"`
+	Timeline        []TimelineEvent `json:"timeline"`
+	TotalDeadlines  int             `json:"total_deadlines"`
+}
+
+// GetTimeline returns the proceeding event tree (without date calculations)
+func (s *DetermineService) GetTimeline(proceedingTypeCode string) ([]TimelineEvent, *models.ProceedingType, error) {
+	rules, pt, err := s.rules.GetFullTimeline(proceedingTypeCode)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	tree := buildTimelineTree(rules)
+	return tree, pt, nil
+}
+
+// Determine calculates the full timeline with cascading dates
+func (s *DetermineService) Determine(req DetermineRequest) (*DetermineResponse, error) {
+	timeline, pt, err := s.GetTimeline(req.ProceedingType)
+	if err != nil {
+		return nil, fmt.Errorf("loading timeline: %w", err)
+	}
+
+	triggerDate, err := time.Parse("2006-01-02", req.TriggerEventDate)
+	if err != nil {
+		return nil, fmt.Errorf("invalid trigger_event_date: %w", err)
+	}
+
+	conditions := req.Conditions
+	if conditions == nil {
+		conditions = make(map[string]bool)
+	}
+
+	total := s.calculateDates(timeline, triggerDate, conditions)
+
+	return &DetermineResponse{
+		ProceedingType:  pt.Code,
+		ProceedingName:  pt.Name,
+		ProceedingColor: pt.DefaultColor,
+		TriggerDate:     req.TriggerEventDate,
+		Timeline:        timeline,
+		TotalDeadlines:  total,
+	}, nil
+}
+
+// calculateDates walks the tree and calculates dates for each node
+func (s *DetermineService) calculateDates(events []TimelineEvent, parentDate time.Time, conditions map[string]bool) int {
+	total := 0
+	for i := range events {
+		ev := &events[i]
+
+		// Skip inactive spawns: if this is a spawn node and conditions don't include it, skip
+		if ev.IsSpawn && !conditions[ev.ID] {
+			continue
+		}
+
+		durationValue := ev.DurationValue
+		durationUnit := ev.DurationUnit
+		ruleCode := ev.RuleCode
+
+		// Apply conditional logic
+		if ev.HasCondition && ev.ConditionRuleID != "" {
+			if conditions[ev.ConditionRuleID] {
+				if ev.AltDurationValue != nil {
+					durationValue = *ev.AltDurationValue
+				}
+				if ev.AltDurationUnit != "" {
+					durationUnit = ev.AltDurationUnit
+				}
+				if ev.AltRuleCode != "" {
+					ruleCode = ev.AltRuleCode
+				}
+			}
+		}
+
+		// Calculate this node's date
+		if durationValue > 0 {
+			rule := models.DeadlineRule{
+				DurationValue: durationValue,
+				DurationUnit:  durationUnit,
+			}
+			adjusted, original, wasAdjusted := s.calculator.CalculateEndDate(parentDate, rule)
+			ev.Date = adjusted.Format("2006-01-02")
+			ev.OriginalDate = original.Format("2006-01-02")
+			ev.WasAdjusted = wasAdjusted
+		} else {
+			ev.Date = parentDate.Format("2006-01-02")
+			ev.OriginalDate = parentDate.Format("2006-01-02")
+		}
+
+		ev.RuleCode = ruleCode
+		total++
+
+		// Recurse: children's dates cascade from this node's date
+		if len(ev.Children) > 0 {
+			childDate, _ := time.Parse("2006-01-02", ev.Date)
+			total += s.calculateDates(ev.Children, childDate, conditions)
+		}
+	}
+	return total
+}
+
+// buildTimelineTree converts flat rules to a tree of TimelineEvents
+func buildTimelineTree(rules []models.DeadlineRule) []TimelineEvent {
+	nodeMap := make(map[string]*TimelineEvent, len(rules))
+	var roots []TimelineEvent
+
+	// Create event nodes
+	for _, r := range rules {
+		ev := ruleToEvent(r)
+		nodeMap[r.ID.String()] = &ev
+	}
+
+	// Build tree by parent_id
+	for _, r := range rules {
+		ev := nodeMap[r.ID.String()]
+		if r.ParentID != nil {
+			parentKey := r.ParentID.String()
+			if parent, ok := nodeMap[parentKey]; ok {
+				parent.Children = append(parent.Children, *ev)
+				continue
+			}
+		}
+		roots = append(roots, *ev)
+	}
+
+	return roots
+}
+
+func ruleToEvent(r models.DeadlineRule) TimelineEvent {
+	ev := TimelineEvent{
+		ID:            r.ID.String(),
+		Name:          r.Name,
+		IsMandatory:   r.IsMandatory,
+		DurationValue: r.DurationValue,
+		DurationUnit:  r.DurationUnit,
+		IsSpawn:       r.IsSpawn,
+		HasCondition:  r.ConditionRuleID != nil,
+	}
+	if r.Code != nil {
+		ev.Code = *r.Code
+	}
+	if r.Description != nil {
+		ev.Description = *r.Description
+	}
+	if r.PrimaryParty != nil {
+		ev.PrimaryParty = *r.PrimaryParty
+	}
+	if r.EventType != nil {
+		ev.EventType = *r.EventType
+	}
+	if r.RuleCode != nil {
+		ev.RuleCode = *r.RuleCode
+	}
+	if r.DeadlineNotes != nil {
+		ev.DeadlineNotes = *r.DeadlineNotes
+	}
+	if r.SpawnLabel != nil {
+		ev.SpawnLabel = *r.SpawnLabel
+	}
+	if r.ConditionRuleID != nil {
+		ev.ConditionRuleID = r.ConditionRuleID.String()
+	}
+	if r.AltRuleCode != nil {
+		ev.AltRuleCode = *r.AltRuleCode
+	}
+	ev.AltDurationValue = r.AltDurationValue
+	if r.AltDurationUnit != nil {
+		ev.AltDurationUnit = *r.AltDurationUnit
+	}
+	return ev
+}

backend/internal/services/document_service.go

@@ -18,10 +18,11 @@ const documentBucket = "kanzlai-documents"
 type DocumentService struct {
 	db      *sqlx.DB
 	storage *StorageClient
+	audit   *AuditService
 }
 
-func NewDocumentService(db *sqlx.DB, storage *StorageClient) *DocumentService {
-	return &DocumentService{db: db, storage: storage}
+func NewDocumentService(db *sqlx.DB, storage *StorageClient, audit *AuditService) *DocumentService {
+	return &DocumentService{db: db, storage: storage, audit: audit}
 }
 
 type CreateDocumentInput struct {
@@ -97,6 +98,7 @@ func (s *DocumentService) Create(ctx context.Context, tenantID, caseID, userID u
 	if err := s.db.GetContext(ctx, &doc, "SELECT * FROM documents WHERE id = $1", id); err != nil {
 		return nil, fmt.Errorf("fetching created document: %w", err)
 	}
+	s.audit.Log(ctx, "create", "document", &id, nil, doc)
 	return &doc, nil
 }
 
@@ -151,6 +153,7 @@ func (s *DocumentService) Delete(ctx context.Context, tenantID, docID, userID uu
 	// Log case event
 	createEvent(ctx, s.db, tenantID, doc.CaseID, userID, "document_deleted",
 		fmt.Sprintf("Document deleted: %s", doc.Title), nil)
+	s.audit.Log(ctx, "delete", "document", &docID, doc, nil)
 
 	return nil
 }

backend/internal/services/note_service.go

@@ -13,11 +13,12 @@ import (
 )
 
 type NoteService struct {
-	db *sqlx.DB
+	db    *sqlx.DB
+	audit *AuditService
 }
 
-func NewNoteService(db *sqlx.DB) *NoteService {
-	return &NoteService{db: db}
+func NewNoteService(db *sqlx.DB, audit *AuditService) *NoteService {
+	return &NoteService{db: db, audit: audit}
 }
 
 // ListByParent returns all notes for a given parent entity, scoped to tenant.
@@ -68,6 +69,7 @@ func (s *NoteService) Create(ctx context.Context, tenantID uuid.UUID, createdBy
 	if err != nil {
 		return nil, fmt.Errorf("creating note: %w", err)
 	}
+	s.audit.Log(ctx, "create", "note", &id, nil, n)
 	return &n, nil
 }
 
@@ -85,6 +87,7 @@ func (s *NoteService) Update(ctx context.Context, tenantID, noteID uuid.UUID, co
 		}
 		return nil, fmt.Errorf("updating note: %w", err)
 	}
+	s.audit.Log(ctx, "update", "note", &noteID, nil, n)
 	return &n, nil
 }
 
@@ -101,6 +104,7 @@ func (s *NoteService) Delete(ctx context.Context, tenantID, noteID uuid.UUID) er
 	if rows == 0 {
 		return fmt.Errorf("note not found")
 	}
+	s.audit.Log(ctx, "delete", "note", &noteID, nil, nil)
 	return nil
 }
 

backend/internal/services/notification_service.go

@@ -0,0 +1,501 @@
+package services
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os/exec"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/jmoiron/sqlx"
+	"github.com/lib/pq"
+
+	"mgit.msbls.de/m/KanzlAI-mGMT/internal/models"
+)
+
+// NotificationService handles notification CRUD, deadline reminders, and email sending.
+type NotificationService struct {
+	db     *sqlx.DB
+	stopCh chan struct{}
+	wg     sync.WaitGroup
+}
+
+// NewNotificationService creates a new notification service.
+func NewNotificationService(db *sqlx.DB) *NotificationService {
+	return &NotificationService{
+		db:     db,
+		stopCh: make(chan struct{}),
+	}
+}
+
+// Start launches the background reminder checker (every hour) and daily digest (8am).
+func (s *NotificationService) Start() {
+	s.wg.Add(1)
+	go s.backgroundLoop()
+}
+
+// Stop gracefully shuts down background workers.
+func (s *NotificationService) Stop() {
+	close(s.stopCh)
+	s.wg.Wait()
+}
+
+func (s *NotificationService) backgroundLoop() {
+	defer s.wg.Done()
+
+	// Check reminders on startup
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
+	s.CheckDeadlineReminders(ctx)
+	cancel()
+
+	reminderTicker := time.NewTicker(1 * time.Hour)
+	defer reminderTicker.Stop()
+
+	// Digest ticker: check every 15 minutes, send at 8am
+	digestTicker := time.NewTicker(15 * time.Minute)
+	defer digestTicker.Stop()
+
+	var lastDigestDate string
+
+	for {
+		select {
+		case <-s.stopCh:
+			return
+		case <-reminderTicker.C:
+			ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
+			s.CheckDeadlineReminders(ctx)
+			cancel()
+		case now := <-digestTicker.C:
+			today := now.Format("2006-01-02")
+			hour := now.Hour()
+			if hour >= 8 && lastDigestDate != today {
+				lastDigestDate = today
+				ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
+				s.SendDailyDigests(ctx)
+				cancel()
+			}
+		}
+	}
+}
+
+// CheckDeadlineReminders finds deadlines due in N days matching user preferences and creates notifications.
+func (s *NotificationService) CheckDeadlineReminders(ctx context.Context) {
+	slog.Info("checking deadline reminders")
+
+	// Get all user preferences with email enabled
+	var prefs []models.NotificationPreferences
+	err := s.db.SelectContext(ctx, &prefs,
+		`SELECT user_id, tenant_id, deadline_reminder_days, email_enabled, daily_digest, created_at, updated_at
+		 FROM notification_preferences`)
+	if err != nil {
+		slog.Error("failed to load notification preferences", "error", err)
+		return
+	}
+
+	if len(prefs) == 0 {
+		return
+	}
+
+	// Collect all unique reminder day values across all users
+	daySet := make(map[int64]bool)
+	for _, p := range prefs {
+		for _, d := range p.DeadlineReminderDays {
+			daySet[d] = true
+		}
+	}
+	if len(daySet) == 0 {
+		return
+	}
+
+	// Build array of target dates
+	today := time.Now().Truncate(24 * time.Hour)
+	var targetDates []string
+	dayToDate := make(map[string]int64)
+	for d := range daySet {
+		target := today.AddDate(0, 0, int(d))
+		dateStr := target.Format("2006-01-02")
+		targetDates = append(targetDates, dateStr)
+		dayToDate[dateStr] = d
+	}
+
+	// Also check overdue deadlines
+	todayStr := today.Format("2006-01-02")
+
+	// Find pending deadlines matching target dates
+	type deadlineRow struct {
+		models.Deadline
+		CaseTitle  string `db:"case_title"`
+		CaseNumber string `db:"case_number"`
+	}
+
+	// Reminder deadlines (due in N days)
+	var reminderDeadlines []deadlineRow
+	query, args, err := sqlx.In(
+		`SELECT d.*, c.title AS case_title, c.case_number
+		 FROM deadlines d
+		 JOIN cases c ON c.id = d.case_id
+		 WHERE d.status = 'pending' AND d.due_date IN (?)`,
+		targetDates)
+	if err == nil {
+		query = s.db.Rebind(query)
+		err = s.db.SelectContext(ctx, &reminderDeadlines, query, args...)
+	}
+	if err != nil {
+		slog.Error("failed to query reminder deadlines", "error", err)
+	}
+
+	// Overdue deadlines
+	var overdueDeadlines []deadlineRow
+	err = s.db.SelectContext(ctx, &overdueDeadlines,
+		`SELECT d.*, c.title AS case_title, c.case_number
+		 FROM deadlines d
+		 JOIN cases c ON c.id = d.case_id
+		 WHERE d.status = 'pending' AND d.due_date < $1`, todayStr)
+	if err != nil {
+		slog.Error("failed to query overdue deadlines", "error", err)
+	}
+
+	// Create notifications for each user based on their tenant and preferences
+	for _, pref := range prefs {
+		// Reminder notifications
+		for _, dl := range reminderDeadlines {
+			if dl.TenantID != pref.TenantID {
+				continue
+			}
+			daysUntil := dayToDate[dl.DueDate]
+			// Check if this user cares about this many days
+			if !containsDay(pref.DeadlineReminderDays, daysUntil) {
+				continue
+			}
+
+			title := fmt.Sprintf("Frist in %d Tagen: %s", daysUntil, dl.Title)
+			body := fmt.Sprintf("Akte %s — %s\nFällig am %s", dl.CaseNumber, dl.CaseTitle, dl.DueDate)
+			entityType := "deadline"
+
+			s.CreateNotification(ctx, CreateNotificationInput{
+				TenantID:   pref.TenantID,
+				UserID:     pref.UserID,
+				Type:       "deadline_reminder",
+				EntityType: &entityType,
+				EntityID:   &dl.ID,
+				Title:      title,
+				Body:       &body,
+				SendEmail:  pref.EmailEnabled && !pref.DailyDigest,
+			})
+		}
+
+		// Overdue notifications
+		for _, dl := range overdueDeadlines {
+			if dl.TenantID != pref.TenantID {
+				continue
+			}
+
+			title := fmt.Sprintf("Frist überfällig: %s", dl.Title)
+			body := fmt.Sprintf("Akte %s — %s\nFällig seit %s", dl.CaseNumber, dl.CaseTitle, dl.DueDate)
+			entityType := "deadline"
+
+			s.CreateNotification(ctx, CreateNotificationInput{
+				TenantID:   pref.TenantID,
+				UserID:     pref.UserID,
+				Type:       "deadline_overdue",
+				EntityType: &entityType,
+				EntityID:   &dl.ID,
+				Title:      title,
+				Body:       &body,
+				SendEmail:  pref.EmailEnabled && !pref.DailyDigest,
+			})
+		}
+	}
+}
+
+// SendDailyDigests compiles pending notifications into one email per user.
+func (s *NotificationService) SendDailyDigests(ctx context.Context) {
+	slog.Info("sending daily digests")
+
+	// Find users with daily_digest enabled
+	var prefs []models.NotificationPreferences
+	err := s.db.SelectContext(ctx, &prefs,
+		`SELECT user_id, tenant_id, deadline_reminder_days, email_enabled, daily_digest, created_at, updated_at
+		 FROM notification_preferences
+		 WHERE daily_digest = true AND email_enabled = true`)
+	if err != nil {
+		slog.Error("failed to load digest preferences", "error", err)
+		return
+	}
+
+	for _, pref := range prefs {
+		// Get unsent notifications for this user from the last 24 hours
+		var notifications []models.Notification
+		err := s.db.SelectContext(ctx, &notifications,
+			`SELECT id, tenant_id, user_id, type, entity_type, entity_id, title, body, sent_at, read_at, created_at
+			 FROM notifications
+			 WHERE user_id = $1 AND tenant_id = $2 AND sent_at IS NULL
+			   AND created_at > now() - interval '24 hours'
+			 ORDER BY created_at DESC`,
+			pref.UserID, pref.TenantID)
+		if err != nil {
+			slog.Error("failed to load unsent notifications", "error", err, "user_id", pref.UserID)
+			continue
+		}
+
+		if len(notifications) == 0 {
+			continue
+		}
+
+		// Get user email
+		email := s.getUserEmail(ctx, pref.UserID)
+		if email == "" {
+			continue
+		}
+
+		// Build digest
+		var lines []string
+		lines = append(lines, fmt.Sprintf("Guten Morgen! Hier ist Ihre Tagesübersicht mit %d Benachrichtigungen:\n", len(notifications)))
+		for _, n := range notifications {
+			body := ""
+			if n.Body != nil {
+				body = " — " + *n.Body
+			}
+			lines = append(lines, fmt.Sprintf("• %s%s", n.Title, body))
+		}
+		lines = append(lines, "\n---\nKanzlAI Kanzleimanagement")
+
+		subject := fmt.Sprintf("KanzlAI Tagesübersicht — %d Benachrichtigungen", len(notifications))
+		bodyText := strings.Join(lines, "\n")
+
+		if err := SendEmail(email, subject, bodyText); err != nil {
+			slog.Error("failed to send digest email", "error", err, "user_id", pref.UserID)
+			continue
+		}
+
+		// Mark all as sent
+		ids := make([]uuid.UUID, len(notifications))
+		for i, n := range notifications {
+			ids[i] = n.ID
+		}
+		query, args, err := sqlx.In(
+			`UPDATE notifications SET sent_at = now() WHERE id IN (?)`, ids)
+		if err == nil {
+			query = s.db.Rebind(query)
+			_, err = s.db.ExecContext(ctx, query, args...)
+		}
+		if err != nil {
+			slog.Error("failed to mark digest notifications sent", "error", err)
+		}
+
+		slog.Info("sent daily digest", "user_id", pref.UserID, "count", len(notifications))
+	}
+}
+
+// CreateNotificationInput holds the data for creating a notification.
+type CreateNotificationInput struct {
+	TenantID   uuid.UUID
+	UserID     uuid.UUID
+	Type       string
+	EntityType *string
+	EntityID   *uuid.UUID
+	Title      string
+	Body       *string
+	SendEmail  bool
+}
+
+// CreateNotification stores a notification in the DB and optionally sends an email.
+func (s *NotificationService) CreateNotification(ctx context.Context, input CreateNotificationInput) (*models.Notification, error) {
+	// Dedup: check if we already sent this notification today
+	if input.EntityID != nil {
+		var count int
+		err := s.db.GetContext(ctx, &count,
+			`SELECT COUNT(*) FROM notifications
+			 WHERE user_id = $1 AND entity_id = $2 AND type = $3
+			   AND created_at::date = CURRENT_DATE`,
+			input.UserID, input.EntityID, input.Type)
+		if err == nil && count > 0 {
+			return nil, nil // Already notified today
+		}
+	}
+
+	var n models.Notification
+	err := s.db.QueryRowxContext(ctx,
+		`INSERT INTO notifications (tenant_id, user_id, type, entity_type, entity_id, title, body)
+		 VALUES ($1, $2, $3, $4, $5, $6, $7)
+		 RETURNING id, tenant_id, user_id, type, entity_type, entity_id, title, body, sent_at, read_at, created_at`,
+		input.TenantID, input.UserID, input.Type, input.EntityType, input.EntityID,
+		input.Title, input.Body).StructScan(&n)
+	if err != nil {
+		slog.Error("failed to create notification", "error", err)
+		return nil, fmt.Errorf("create notification: %w", err)
+	}
+
+	// Send email immediately if requested (non-digest users)
+	if input.SendEmail {
+		email := s.getUserEmail(ctx, input.UserID)
+		if email != "" {
+			go func() {
+				if err := SendEmail(email, input.Title, derefStr(input.Body)); err != nil {
+					slog.Error("failed to send notification email", "error", err, "user_id", input.UserID)
+				} else {
+					// Mark as sent
+					_, _ = s.db.Exec(`UPDATE notifications SET sent_at = now() WHERE id = $1`, n.ID)
+				}
+			}()
+		}
+	}
+
+	return &n, nil
+}
+
+// ListForUser returns notifications for a user in a tenant, paginated.
+func (s *NotificationService) ListForUser(ctx context.Context, tenantID, userID uuid.UUID, limit, offset int) ([]models.Notification, int, error) {
+	if limit <= 0 {
+		limit = 50
+	}
+	if limit > 200 {
+		limit = 200
+	}
+
+	var total int
+	err := s.db.GetContext(ctx, &total,
+		`SELECT COUNT(*) FROM notifications WHERE user_id = $1 AND tenant_id = $2`,
+		userID, tenantID)
+	if err != nil {
+		return nil, 0, fmt.Errorf("count notifications: %w", err)
+	}
+
+	var notifications []models.Notification
+	err = s.db.SelectContext(ctx, &notifications,
+		`SELECT id, tenant_id, user_id, type, entity_type, entity_id, title, body, sent_at, read_at, created_at
+		 FROM notifications
+		 WHERE user_id = $1 AND tenant_id = $2
+		 ORDER BY created_at DESC
+		 LIMIT $3 OFFSET $4`,
+		userID, tenantID, limit, offset)
+	if err != nil {
+		return nil, 0, fmt.Errorf("list notifications: %w", err)
+	}
+
+	return notifications, total, nil
+}
+
+// UnreadCount returns the number of unread notifications for a user.
+func (s *NotificationService) UnreadCount(ctx context.Context, tenantID, userID uuid.UUID) (int, error) {
+	var count int
+	err := s.db.GetContext(ctx, &count,
+		`SELECT COUNT(*) FROM notifications WHERE user_id = $1 AND tenant_id = $2 AND read_at IS NULL`,
+		userID, tenantID)
+	return count, err
+}
+
+// MarkRead marks a single notification as read.
+func (s *NotificationService) MarkRead(ctx context.Context, tenantID, userID, notificationID uuid.UUID) error {
+	result, err := s.db.ExecContext(ctx,
+		`UPDATE notifications SET read_at = now()
+		 WHERE id = $1 AND user_id = $2 AND tenant_id = $3 AND read_at IS NULL`,
+		notificationID, userID, tenantID)
+	if err != nil {
+		return fmt.Errorf("mark notification read: %w", err)
+	}
+	rows, _ := result.RowsAffected()
+	if rows == 0 {
+		return fmt.Errorf("notification not found or already read")
+	}
+	return nil
+}
+
+// MarkAllRead marks all notifications as read for a user.
+func (s *NotificationService) MarkAllRead(ctx context.Context, tenantID, userID uuid.UUID) error {
+	_, err := s.db.ExecContext(ctx,
+		`UPDATE notifications SET read_at = now()
+		 WHERE user_id = $1 AND tenant_id = $2 AND read_at IS NULL`,
+		userID, tenantID)
+	return err
+}
+
+// GetPreferences returns notification preferences for a user, creating defaults if needed.
+func (s *NotificationService) GetPreferences(ctx context.Context, tenantID, userID uuid.UUID) (*models.NotificationPreferences, error) {
+	var pref models.NotificationPreferences
+	err := s.db.GetContext(ctx, &pref,
+		`SELECT user_id, tenant_id, deadline_reminder_days, email_enabled, daily_digest, created_at, updated_at
+		 FROM notification_preferences
+		 WHERE user_id = $1 AND tenant_id = $2`,
+		userID, tenantID)
+	if err != nil {
+		// Return defaults if no preferences set
+		return &models.NotificationPreferences{
+			UserID:               userID,
+			TenantID:             tenantID,
+			DeadlineReminderDays: pq.Int64Array{7, 3, 1},
+			EmailEnabled:         true,
+			DailyDigest:          false,
+		}, nil
+	}
+	return &pref, nil
+}
+
+// UpdatePreferences upserts notification preferences for a user.
+func (s *NotificationService) UpdatePreferences(ctx context.Context, tenantID, userID uuid.UUID, input UpdatePreferencesInput) (*models.NotificationPreferences, error) {
+	var pref models.NotificationPreferences
+	err := s.db.QueryRowxContext(ctx,
+		`INSERT INTO notification_preferences (user_id, tenant_id, deadline_reminder_days, email_enabled, daily_digest)
+		 VALUES ($1, $2, $3, $4, $5)
+		 ON CONFLICT (user_id, tenant_id)
+		 DO UPDATE SET deadline_reminder_days = $3, email_enabled = $4, daily_digest = $5, updated_at = now()
+		 RETURNING user_id, tenant_id, deadline_reminder_days, email_enabled, daily_digest, created_at, updated_at`,
+		userID, tenantID, pq.Int64Array(input.DeadlineReminderDays), input.EmailEnabled, input.DailyDigest).StructScan(&pref)
+	if err != nil {
+		return nil, fmt.Errorf("update preferences: %w", err)
+	}
+	return &pref, nil
+}
+
+// UpdatePreferencesInput holds the data for updating notification preferences.
+type UpdatePreferencesInput struct {
+	DeadlineReminderDays []int64 `json:"deadline_reminder_days"`
+	EmailEnabled         bool    `json:"email_enabled"`
+	DailyDigest          bool    `json:"daily_digest"`
+}
+
+// SendEmail sends an email using the `m mail send` CLI command.
+func SendEmail(to, subject, body string) error {
+	cmd := exec.Command("m", "mail", "send",
+		"--to", to,
+		"--subject", subject,
+		"--body", body,
+		"--yes")
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("m mail send failed: %w (output: %s)", err, string(output))
+	}
+	slog.Info("email sent", "to", to, "subject", subject)
+	return nil
+}
+
+// getUserEmail looks up the email for a user from Supabase auth.users.
+func (s *NotificationService) getUserEmail(ctx context.Context, userID uuid.UUID) string {
+	var email string
+	err := s.db.GetContext(ctx, &email,
+		`SELECT email FROM auth.users WHERE id = $1`, userID)
+	if err != nil {
+		slog.Error("failed to get user email", "error", err, "user_id", userID)
+		return ""
+	}
+	return email
+}
+
+func containsDay(arr pq.Int64Array, day int64) bool {
+	for _, d := range arr {
+		if d == day {
+			return true
+		}
+	}
+	return false
+}
+
+func derefStr(s *string) string {
+	if s == nil {
+		return ""
+	}
+	return *s
+}

backend/internal/services/party_service.go

@@ -13,11 +13,12 @@ import (
 )
 
 type PartyService struct {
-	db *sqlx.DB
+	db    *sqlx.DB
+	audit *AuditService
 }
 
-func NewPartyService(db *sqlx.DB) *PartyService {
-	return &PartyService{db: db}
+func NewPartyService(db *sqlx.DB, audit *AuditService) *PartyService {
+	return &PartyService{db: db, audit: audit}
 }
 
 type CreatePartyInput struct {
@@ -79,6 +80,7 @@ func (s *PartyService) Create(ctx context.Context, tenantID, caseID uuid.UUID, u
 	if err := s.db.GetContext(ctx, &party, "SELECT * FROM parties WHERE id = $1", id); err != nil {
 		return nil, fmt.Errorf("fetching created party: %w", err)
 	}
+	s.audit.Log(ctx, "create", "party", &id, nil, party)
 	return &party, nil
 }
 
@@ -135,6 +137,7 @@ func (s *PartyService) Update(ctx context.Context, tenantID, partyID uuid.UUID,
 	if err := s.db.GetContext(ctx, &updated, "SELECT * FROM parties WHERE id = $1", partyID); err != nil {
 		return nil, fmt.Errorf("fetching updated party: %w", err)
 	}
+	s.audit.Log(ctx, "update", "party", &partyID, current, updated)
 	return &updated, nil
 }
 
@@ -148,5 +151,6 @@ func (s *PartyService) Delete(ctx context.Context, tenantID, partyID uuid.UUID)
 	if rows == 0 {
 		return sql.ErrNoRows
 	}
+	s.audit.Log(ctx, "delete", "party", &partyID, nil, nil)
 	return nil
 }

backend/internal/services/tenant_service.go

@@ -13,11 +13,12 @@ import (
 )
 
 type TenantService struct {
-	db *sqlx.DB
+	db    *sqlx.DB
+	audit *AuditService
 }
 
-func NewTenantService(db *sqlx.DB) *TenantService {
-	return &TenantService{db: db}
+func NewTenantService(db *sqlx.DB, audit *AuditService) *TenantService {
+	return &TenantService{db: db, audit: audit}
 }
 
 // Create creates a new tenant and assigns the creator as owner.
@@ -49,6 +50,7 @@ func (s *TenantService) Create(ctx context.Context, userID uuid.UUID, name, slug
 		return nil, fmt.Errorf("commit: %w", err)
 	}
 
+	s.audit.Log(ctx, "create", "tenant", &tenant.ID, nil, tenant)
 	return &tenant, nil
 }
 
@@ -101,6 +103,19 @@ func (s *TenantService) GetUserRole(ctx context.Context, userID, tenantID uuid.U
 	return role, nil
 }
 
+// VerifyAccess checks if a user has access to a given tenant.
+func (s *TenantService) VerifyAccess(ctx context.Context, userID, tenantID uuid.UUID) (bool, error) {
+	var exists bool
+	err := s.db.GetContext(ctx, &exists,
+		`SELECT EXISTS(SELECT 1 FROM user_tenants WHERE user_id = $1 AND tenant_id = $2)`,
+		userID, tenantID,
+	)
+	if err != nil {
+		return false, fmt.Errorf("verify tenant access: %w", err)
+	}
+	return exists, nil
+}
+
 // FirstTenantForUser returns the user's first tenant (by name), used as default.
 func (s *TenantService) FirstTenantForUser(ctx context.Context, userID uuid.UUID) (*uuid.UUID, error) {
 	var tenantID uuid.UUID
@@ -171,6 +186,7 @@ func (s *TenantService) InviteByEmail(ctx context.Context, tenantID uuid.UUID, e
 		return nil, fmt.Errorf("invite user: %w", err)
 	}
 
+	s.audit.Log(ctx, "create", "membership", &tenantID, nil, ut)
 	return &ut, nil
 }
 
@@ -186,6 +202,7 @@ func (s *TenantService) UpdateSettings(ctx context.Context, tenantID uuid.UUID,
 	if err != nil {
 		return nil, fmt.Errorf("update settings: %w", err)
 	}
+	s.audit.Log(ctx, "update", "settings", &tenantID, nil, settings)
 	return &tenant, nil
 }
 
@@ -257,5 +274,6 @@ func (s *TenantService) RemoveMember(ctx context.Context, tenantID, userID uuid.
 		return fmt.Errorf("remove member: %w", err)
 	}
 
+	s.audit.Log(ctx, "delete", "membership", &tenantID, map[string]any{"user_id": userID, "role": role}, nil)
 	return nil
 }

backend/seed/seed_upc_timeline.sql

@@ -0,0 +1,466 @@
+-- UPC Proceeding Timeline: Full event tree with conditional deadlines
+-- Ported from youpc.org migrations 039 + 040
+-- Run against kanzlai schema in flexsiebels Supabase instance
+
+-- ========================================
+-- 1. Add is_spawn + spawn_label columns
+-- ========================================
+ALTER TABLE deadline_rules
+    ADD COLUMN IF NOT EXISTS is_spawn BOOLEAN DEFAULT false,
+    ADD COLUMN IF NOT EXISTS spawn_label TEXT;
+
+-- ========================================
+-- 2. Clear existing UPC rules (fresh seed)
+-- ========================================
+DELETE FROM deadline_rules WHERE proceeding_type_id IN (
+    SELECT id FROM proceeding_types WHERE code IN ('INF', 'REV', 'CCR', 'APM', 'APP', 'AMD')
+);
+
+-- ========================================
+-- 3. Ensure all proceeding types exist
+-- ========================================
+INSERT INTO proceeding_types (code, name, description, is_active, sort_order, default_color)
+VALUES
+    ('INF', 'Infringement', 'Patent infringement proceedings', true, 1, '#3b82f6'),
+    ('REV', 'Revocation', 'Standalone revocation proceedings', true, 2, '#ef4444'),
+    ('CCR', 'Counterclaim for Revocation', 'Counterclaim for revocation within infringement', true, 3, '#ef4444'),
+    ('APM', 'Provisional Measures', 'Application for preliminary injunction', true, 4, '#f59e0b'),
+    ('APP', 'Appeal', 'Appeal to the Court of Appeal', true, 5, '#8b5cf6'),
+    ('AMD', 'Application to Amend Patent', 'Sub-proceeding for patent amendment during revocation', true, 6, '#10b981')
+ON CONFLICT (code) DO UPDATE SET
+    name = EXCLUDED.name,
+    description = EXCLUDED.description,
+    default_color = EXCLUDED.default_color,
+    sort_order = EXCLUDED.sort_order,
+    is_active = EXCLUDED.is_active;
+
+-- ========================================
+-- 4. Seed all proceeding events
+-- ========================================
+DO $$
+DECLARE
+    v_inf INTEGER;
+    v_rev INTEGER;
+    v_ccr INTEGER;
+    v_apm INTEGER;
+    v_app INTEGER;
+    v_amd INTEGER;
+    -- INF event IDs
+    v_inf_soc UUID;
+    v_inf_sod UUID;
+    v_inf_reply UUID;
+    v_inf_rejoin UUID;
+    v_inf_interim UUID;
+    v_inf_oral UUID;
+    v_inf_decision UUID;
+    v_inf_prelim UUID;
+    -- CCR event IDs
+    v_ccr_root UUID;
+    v_ccr_defence UUID;
+    v_ccr_reply UUID;
+    v_ccr_rejoin UUID;
+    v_ccr_interim UUID;
+    v_ccr_oral UUID;
+    v_ccr_decision UUID;
+    -- REV event IDs
+    v_rev_app UUID;
+    v_rev_defence UUID;
+    v_rev_reply UUID;
+    v_rev_rejoin UUID;
+    v_rev_interim UUID;
+    v_rev_oral UUID;
+    v_rev_decision UUID;
+    -- PI event IDs
+    v_pi_app UUID;
+    v_pi_resp UUID;
+    v_pi_oral UUID;
+    -- APP event IDs
+    v_app_notice UUID;
+    v_app_grounds UUID;
+    v_app_response UUID;
+    v_app_oral UUID;
+BEGIN
+    SELECT id INTO v_inf FROM proceeding_types WHERE code = 'INF';
+    SELECT id INTO v_rev FROM proceeding_types WHERE code = 'REV';
+    SELECT id INTO v_ccr FROM proceeding_types WHERE code = 'CCR';
+    SELECT id INTO v_apm FROM proceeding_types WHERE code = 'APM';
+    SELECT id INTO v_app FROM proceeding_types WHERE code = 'APP';
+    SELECT id INTO v_amd FROM proceeding_types WHERE code = 'AMD';
+
+    -- ========================================
+    -- INFRINGEMENT PROCEEDINGS
+    -- ========================================
+
+    -- Root: Statement of Claim
+    v_inf_soc := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_inf_soc, v_inf, NULL, 'inf.soc', 'Statement of Claim',
+        'Claimant files the statement of claim with the Registry',
+        'claimant', 'filing', true, 0, 'months', NULL, NULL, false, NULL, 0, true);
+
+    -- Preliminary Objection (from SoC)
+    v_inf_prelim := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_inf_prelim, v_inf, v_inf_soc, 'inf.prelim', 'Preliminary Objection',
+        'Defendant raises preliminary objection (jurisdiction, admissibility)',
+        'defendant', 'filing', false, 1, 'months', 'R.19',
+        'Rarely triggers separate decision; usually decided with main case',
+        false, NULL, 1, true);
+
+    -- Statement of Defence (from SoC)
+    v_inf_sod := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_inf_sod, v_inf, v_inf_soc, 'inf.sod', 'Statement of Defence',
+        'Defendant files the statement of defence',
+        'defendant', 'filing', true, 3, 'months', 'RoP.023', NULL,
+        false, NULL, 2, true);
+
+    -- Reply to Defence (from SoD) — CONDITIONAL: rule code changes if CCR
+    v_inf_reply := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_inf_reply, v_inf, v_inf_sod, 'inf.reply', 'Reply to Defence',
+        'Claimant''s reply to the statement of defence (includes Defence to Counterclaim if CCR active)',
+        'claimant', 'filing', true, 2, 'months', 'RoP.029b', NULL,
+        false, NULL, 1, true);
+
+    -- Rejoinder (from Reply) — CONDITIONAL: duration changes if CCR
+    v_inf_rejoin := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_inf_rejoin, v_inf, v_inf_reply, 'inf.rejoin', 'Rejoinder',
+        'Defendant''s rejoinder to the reply',
+        'defendant', 'filing', true, 1, 'months', 'RoP.029c', NULL,
+        false, NULL, 0, true);
+
+    -- Interim Conference
+    v_inf_interim := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_inf_interim, v_inf, v_inf_rejoin, 'inf.interim', 'Interim Conference',
+        'Interim conference with the judge-rapporteur',
+        'court', 'hearing', true, 0, 'months', NULL, NULL, false, NULL, 0, true);
+
+    -- Oral Hearing
+    v_inf_oral := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_inf_oral, v_inf, v_inf_interim, 'inf.oral', 'Oral Hearing',
+        'Oral hearing before the panel',
+        'court', 'hearing', true, 0, 'months', NULL, NULL, false, NULL, 0, true);
+
+    -- Decision
+    v_inf_decision := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_inf_decision, v_inf, v_inf_oral, 'inf.decision', 'Decision',
+        'Panel delivers its decision',
+        'court', 'decision', true, 0, 'months', NULL, NULL, false, NULL, 0, true);
+
+    -- Appeal (spawn from Decision — cross-type to APP)
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (gen_random_uuid(), v_app, v_inf_decision, 'inf.appeal', 'Appeal',
+        'Appeal against infringement decision to Court of Appeal',
+        'both', 'filing', true, 2, 'months', 'RoP.220.1', NULL,
+        true, 'Appeal filed', 0, true);
+
+    -- ========================================
+    -- COUNTERCLAIM FOR REVOCATION (spawn from SoD)
+    -- ========================================
+
+    v_ccr_root := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_ccr_root, v_ccr, v_inf_sod, 'ccr.counterclaim', 'Counterclaim for Revocation',
+        'Defendant files counterclaim challenging patent validity (included in SoD)',
+        'defendant', 'filing', true, 0, 'months', NULL, NULL,
+        true, 'Includes counterclaim for revocation', 0, true);
+
+    -- Defence to Counterclaim
+    v_ccr_defence := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_ccr_defence, v_ccr, v_ccr_root, 'ccr.defence', 'Defence to Counterclaim',
+        'Patent proprietor files defence to revocation counterclaim',
+        'claimant', 'filing', true, 3, 'months', 'RoP.050', NULL,
+        false, NULL, 0, true);
+
+    -- Reply in CCR
+    v_ccr_reply := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_ccr_reply, v_ccr, v_ccr_defence, 'ccr.reply', 'Reply in CCR',
+        'Reply in the counterclaim for revocation',
+        'defendant', 'filing', true, 2, 'months', NULL,
+        'Timing overlaps with infringement Rejoinder',
+        false, NULL, 1, true);
+
+    -- Rejoinder in CCR
+    v_ccr_rejoin := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_ccr_rejoin, v_ccr, v_ccr_reply, 'ccr.rejoin', 'Rejoinder in CCR',
+        'Rejoinder in the counterclaim for revocation',
+        'claimant', 'filing', true, 2, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    -- Interim Conference
+    v_ccr_interim := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_ccr_interim, v_ccr, v_ccr_rejoin, 'ccr.interim', 'Interim Conference',
+        'Interim conference covering revocation issues',
+        'court', 'hearing', true, 0, 'months', NULL,
+        'May be combined with infringement IC',
+        false, NULL, 0, true);
+
+    -- Oral Hearing
+    v_ccr_oral := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_ccr_oral, v_ccr, v_ccr_interim, 'ccr.oral', 'Oral Hearing',
+        'Oral hearing on validity',
+        'court', 'hearing', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    -- Decision
+    v_ccr_decision := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_ccr_decision, v_ccr, v_ccr_oral, 'ccr.decision', 'Decision',
+        'Decision on validity of the patent',
+        'court', 'decision', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    -- Appeal from CCR
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (gen_random_uuid(), v_app, v_ccr_decision, 'ccr.appeal', 'Appeal',
+        'Appeal against revocation decision to Court of Appeal',
+        'both', 'filing', true, 2, 'months', 'RoP.220.1', NULL,
+        true, 'Appeal filed', 0, true);
+
+    -- Application to Amend Patent (spawn from Defence to CCR)
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (gen_random_uuid(), v_amd, v_ccr_defence, 'ccr.amend', 'Application to Amend Patent',
+        'Patent proprietor applies to amend the patent during revocation proceedings',
+        'claimant', 'filing', false, 0, 'months', NULL, NULL,
+        true, 'Includes application to amend patent', 2, true);
+
+    -- ========================================
+    -- STANDALONE REVOCATION
+    -- ========================================
+
+    v_rev_app := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_rev_app, v_rev, NULL, 'rev.app', 'Application for Revocation',
+        'Applicant files standalone application for revocation of the patent',
+        'claimant', 'filing', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    v_rev_defence := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_rev_defence, v_rev, v_rev_app, 'rev.defence', 'Defence to Revocation',
+        'Patent proprietor files defence to revocation application',
+        'defendant', 'filing', true, 3, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    v_rev_reply := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_rev_reply, v_rev, v_rev_defence, 'rev.reply', 'Reply',
+        'Reply in standalone revocation proceedings',
+        'claimant', 'filing', true, 2, 'months', NULL, NULL,
+        false, NULL, 1, true);
+
+    v_rev_rejoin := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_rev_rejoin, v_rev, v_rev_reply, 'rev.rejoin', 'Rejoinder',
+        'Rejoinder in standalone revocation proceedings',
+        'defendant', 'filing', true, 2, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    v_rev_interim := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_rev_interim, v_rev, v_rev_rejoin, 'rev.interim', 'Interim Conference',
+        'Interim conference with the judge-rapporteur',
+        'court', 'hearing', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    v_rev_oral := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_rev_oral, v_rev, v_rev_interim, 'rev.oral', 'Oral Hearing',
+        'Oral hearing on validity in standalone revocation',
+        'court', 'hearing', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    v_rev_decision := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_rev_decision, v_rev, v_rev_oral, 'rev.decision', 'Decision',
+        'Decision on patent validity',
+        'court', 'decision', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    -- Appeal from REV
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (gen_random_uuid(), v_app, v_rev_decision, 'rev.appeal', 'Appeal',
+        'Appeal against revocation decision to Court of Appeal',
+        'both', 'filing', true, 2, 'months', 'RoP.220.1', NULL,
+        true, 'Appeal filed', 0, true);
+
+    -- Application to Amend Patent from REV Defence
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (gen_random_uuid(), v_amd, v_rev_defence, 'rev.amend', 'Application to Amend Patent',
+        'Patent proprietor applies to amend the patent',
+        'claimant', 'filing', false, 0, 'months', NULL, NULL,
+        true, 'Includes application to amend patent', 2, true);
+
+    -- ========================================
+    -- PRELIMINARY INJUNCTION
+    -- ========================================
+
+    v_pi_app := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_pi_app, v_apm, NULL, 'pi.app', 'Application for Provisional Measures',
+        'Claimant files application for preliminary injunction',
+        'claimant', 'filing', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    v_pi_resp := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_pi_resp, v_apm, v_pi_app, 'pi.response', 'Response to PI Application',
+        'Defendant files response to preliminary injunction application',
+        'defendant', 'filing', true, 0, 'months', NULL,
+        'Deadline set by court',
+        false, NULL, 0, true);
+
+    v_pi_oral := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_pi_oral, v_apm, v_pi_resp, 'pi.oral', 'Oral Hearing',
+        'Oral hearing on provisional measures',
+        'court', 'hearing', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (gen_random_uuid(), v_apm, v_pi_oral, 'pi.order', 'Order on Provisional Measures',
+        'Court issues order on preliminary injunction',
+        'court', 'decision', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    -- ========================================
+    -- APPEAL (standalone)
+    -- ========================================
+
+    v_app_notice := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_app_notice, v_app, NULL, 'app.notice', 'Notice of Appeal',
+        'Appellant files notice of appeal with the Court of Appeal',
+        'both', 'filing', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    v_app_grounds := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_app_grounds, v_app, v_app_notice, 'app.grounds', 'Statement of Grounds of Appeal',
+        'Appellant files statement of grounds',
+        'both', 'filing', true, 2, 'months', 'RoP.220.1', NULL,
+        false, NULL, 0, true);
+
+    v_app_response := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_app_response, v_app, v_app_grounds, 'app.response', 'Response to Appeal',
+        'Respondent files response to the appeal',
+        'both', 'filing', true, 2, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    v_app_oral := gen_random_uuid();
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (v_app_oral, v_app, v_app_response, 'app.oral', 'Oral Hearing',
+        'Oral hearing before the Court of Appeal',
+        'court', 'hearing', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    INSERT INTO deadline_rules (id, proceeding_type_id, parent_id, code, name, description,
+        primary_party, event_type, is_mandatory, duration_value, duration_unit,
+        rule_code, deadline_notes, is_spawn, spawn_label, sequence_order, is_active)
+    VALUES (gen_random_uuid(), v_app, v_app_oral, 'app.decision', 'Decision',
+        'Court of Appeal delivers its decision',
+        'court', 'decision', true, 0, 'months', NULL, NULL,
+        false, NULL, 0, true);
+
+    -- ========================================
+    -- 5. Set conditional deadlines (from 040)
+    -- ========================================
+
+    -- Reply to Defence: rule code changes when CCR is active
+    -- Default: RoP.029b | With CCR: RoP.029a
+    UPDATE deadline_rules
+    SET condition_rule_id = v_ccr_root,
+        alt_rule_code = 'RoP.029a'
+    WHERE id = v_inf_reply;
+
+    -- Rejoinder: duration changes when CCR is active
+    -- Default: 1 month RoP.029c | With CCR: 2 months RoP.029d
+    UPDATE deadline_rules
+    SET condition_rule_id = v_ccr_root,
+        alt_duration_value = 2,
+        alt_duration_unit = 'months',
+        alt_rule_code = 'RoP.029d'
+    WHERE id = v_inf_rejoin;
+
+END $$;

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

@@ -16,6 +16,7 @@ import {
   UserCheck,
   StickyNote,
   AlertTriangle,
+  ScrollText,
 } from "lucide-react";
 import { format } from "date-fns";
 import { de } from "date-fns/locale";
@@ -46,6 +47,7 @@ const TABS = [
   { segment: "parteien", label: "Parteien", icon: Users },
   { segment: "mitarbeiter", label: "Mitarbeiter", icon: UserCheck },
   { segment: "notizen", label: "Notizen", icon: StickyNote },
+  { segment: "protokoll", label: "Protokoll", icon: ScrollText },
 ] as const;
 
 const TAB_LABELS: Record<string, string> = {
@@ -55,6 +57,7 @@ const TAB_LABELS: Record<string, string> = {
   parteien: "Parteien",
   mitarbeiter: "Mitarbeiter",
   notizen: "Notizen",
+  protokoll: "Protokoll",
 };
 
 function CaseDetailSkeleton() {

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

@@ -0,0 +1,178 @@
+"use client";
+
+import { useQuery } from "@tanstack/react-query";
+import { useParams, useSearchParams } from "next/navigation";
+import { api } from "@/lib/api";
+import type { AuditLogResponse } from "@/lib/types";
+import { format } from "date-fns";
+import { de } from "date-fns/locale";
+import { Loader2, ChevronLeft, ChevronRight } from "lucide-react";
+
+const ACTION_LABELS: Record<string, string> = {
+  create: "Erstellt",
+  update: "Aktualisiert",
+  delete: "Geloescht",
+};
+
+const ACTION_COLORS: Record<string, string> = {
+  create: "bg-emerald-50 text-emerald-700",
+  update: "bg-blue-50 text-blue-700",
+  delete: "bg-red-50 text-red-700",
+};
+
+const ENTITY_LABELS: Record<string, string> = {
+  case: "Akte",
+  deadline: "Frist",
+  appointment: "Termin",
+  document: "Dokument",
+  party: "Partei",
+  note: "Notiz",
+  settings: "Einstellungen",
+  membership: "Mitgliedschaft",
+};
+
+function DiffPreview({
+  oldValues,
+  newValues,
+}: {
+  oldValues?: Record<string, unknown>;
+  newValues?: Record<string, unknown>;
+}) {
+  if (!oldValues && !newValues) return null;
+
+  const allKeys = new Set([
+    ...Object.keys(oldValues ?? {}),
+    ...Object.keys(newValues ?? {}),
+  ]);
+
+  const changes: { key: string; from?: unknown; to?: unknown }[] = [];
+  for (const key of allKeys) {
+    const oldVal = oldValues?.[key];
+    const newVal = newValues?.[key];
+    if (JSON.stringify(oldVal) !== JSON.stringify(newVal)) {
+      changes.push({ key, from: oldVal, to: newVal });
+    }
+  }
+
+  if (changes.length === 0) return null;
+
+  return (
+    <div className="mt-2 space-y-1">
+      {changes.slice(0, 5).map((c) => (
+        <div key={c.key} className="flex items-baseline gap-2 text-xs">
+          <span className="font-medium text-neutral-500">{c.key}:</span>
+          {c.from !== undefined && (
+            <span className="rounded bg-red-50 px-1 text-red-600 line-through">
+              {String(c.from)}
+            </span>
+          )}
+          {c.to !== undefined && (
+            <span className="rounded bg-emerald-50 px-1 text-emerald-600">
+              {String(c.to)}
+            </span>
+          )}
+        </div>
+      ))}
+      {changes.length > 5 && (
+        <span className="text-xs text-neutral-400">
+          +{changes.length - 5} weitere Aenderungen
+        </span>
+      )}
+    </div>
+  );
+}
+
+export default function ProtokollPage() {
+  const { id } = useParams<{ id: string }>();
+  const searchParams = useSearchParams();
+  const page = Number(searchParams.get("page")) || 1;
+
+  const { data, isLoading } = useQuery({
+    queryKey: ["audit-log", id, page],
+    queryFn: () =>
+      api.get<AuditLogResponse>(
+        `/audit-log?entity_id=${id}&page=${page}&limit=50`,
+      ),
+  });
+
+  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?.entries ?? [];
+  const total = data?.total ?? 0;
+  const totalPages = Math.ceil(total / 50);
+
+  if (entries.length === 0) {
+    return (
+      <div className="py-8 text-center text-sm text-neutral-400">
+        Keine Protokolleintraege vorhanden.
+      </div>
+    );
+  }
+
+  return (
+    <div>
+      <div className="space-y-3">
+        {entries.map((entry) => (
+          <div
+            key={entry.id}
+            className="rounded-md border border-neutral-100 bg-white px-4 py-3"
+          >
+            <div className="flex items-start justify-between gap-3">
+              <div className="flex items-center gap-2">
+                <span
+                  className={`inline-block rounded-full px-2 py-0.5 text-xs font-medium ${ACTION_COLORS[entry.action] ?? "bg-neutral-100 text-neutral-600"}`}
+                >
+                  {ACTION_LABELS[entry.action] ?? entry.action}
+                </span>
+                <span className="text-sm font-medium text-neutral-700">
+                  {ENTITY_LABELS[entry.entity_type] ?? entry.entity_type}
+                </span>
+              </div>
+              <span className="shrink-0 text-xs text-neutral-400">
+                {format(new Date(entry.created_at), "d. MMM yyyy, HH:mm", {
+                  locale: de,
+                })}
+              </span>
+            </div>
+            <DiffPreview
+              oldValues={entry.old_values}
+              newValues={entry.new_values}
+            />
+          </div>
+        ))}
+      </div>
+
+      {totalPages > 1 && (
+        <div className="mt-4 flex items-center justify-between">
+          <span className="text-xs text-neutral-400">
+            {total} Eintraege, Seite {page} von {totalPages}
+          </span>
+          <div className="flex gap-1">
+            {page > 1 && (
+              <a
+                href={`?page=${page - 1}`}
+                className="inline-flex items-center gap-1 rounded-md border border-neutral-200 px-2 py-1 text-xs text-neutral-600 hover:bg-neutral-50"
+              >
+                <ChevronLeft className="h-3 w-3" /> Zurueck
+              </a>
+            )}
+            {page < totalPages && (
+              <a
+                href={`?page=${page + 1}`}
+                className="inline-flex items-center gap-1 rounded-md border border-neutral-200 px-2 py-1 text-xs text-neutral-600 hover:bg-neutral-50"
+              >
+                Weiter <ChevronRight className="h-3 w-3" />
+              </a>
+            )}
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}

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

@@ -1,11 +1,12 @@
 "use client";
 
 import { useQuery } from "@tanstack/react-query";
-import { Settings, Calendar, Users } from "lucide-react";
+import { Settings, Calendar, Users, Bell } from "lucide-react";
 import Link from "next/link";
 import { api } from "@/lib/api";
 import type { Tenant } from "@/lib/types";
 import { CalDAVSettings } from "@/components/settings/CalDAVSettings";
+import { NotificationSettings } from "@/components/settings/NotificationSettings";
 import { SkeletonCard } from "@/components/ui/Skeleton";
 import { EmptyState } from "@/components/ui/EmptyState";
 
@@ -97,6 +98,19 @@ export default function EinstellungenPage() {
             </div>
           </section>
 
+          {/* Notification Settings */}
+          <section className="rounded-xl border border-neutral-200 bg-white p-5">
+            <div className="flex items-center gap-2.5 border-b border-neutral-100 pb-3">
+              <Bell className="h-4 w-4 text-neutral-500" />
+              <h2 className="text-sm font-semibold text-neutral-900">
+                Benachrichtigungen
+              </h2>
+            </div>
+            <div className="mt-4">
+              <NotificationSettings />
+            </div>
+          </section>
+
           {/* CalDAV Settings */}
           <section className="rounded-xl border border-neutral-200 bg-white p-5">
             <div className="flex items-center gap-2.5 border-b border-neutral-100 pb-3">

frontend/src/app/(app)/fristen/rechner/page.tsx

@@ -1,28 +1,61 @@
 "use client";
 
 import { DeadlineCalculator } from "@/components/deadlines/DeadlineCalculator";
+import { DeadlineWizard } from "@/components/deadlines/DeadlineWizard";
 import { ArrowLeft } from "lucide-react";
 import Link from "next/link";
+import { useState } from "react";
 
 export default function FristenrechnerPage() {
+  const [mode, setMode] = useState<"wizard" | "quick">("wizard");
+
   return (
     <div className="animate-fade-in space-y-4">
-      <div>
-        <Link
-          href="/fristen"
-          className="mb-2 inline-flex items-center gap-1 text-sm text-neutral-500 transition-colors hover:text-neutral-700"
-        >
-          <ArrowLeft className="h-3.5 w-3.5" />
-          Zurück zu Fristen
-        </Link>
-        <h1 className="text-lg font-semibold text-neutral-900">
-          Fristenrechner
-        </h1>
-        <p className="mt-0.5 text-sm text-neutral-500">
-          Berechnen Sie Fristen basierend auf Verfahrensart und Auslösedatum
-        </p>
+      <div className="flex items-start justify-between">
+        <div>
+          <Link
+            href="/fristen"
+            className="mb-2 inline-flex items-center gap-1 text-sm text-neutral-500 transition-colors hover:text-neutral-700"
+          >
+            <ArrowLeft className="h-3.5 w-3.5" />
+            Zurueck zu Fristen
+          </Link>
+          <h1 className="text-lg font-semibold text-neutral-900">
+            Fristenbestimmung
+          </h1>
+          <p className="mt-0.5 text-sm text-neutral-500">
+            {mode === "wizard"
+              ? "Vollstaendige Verfahrens-Timeline mit automatischer Fristenberechnung"
+              : "Schnellberechnung einzelner Fristen nach Verfahrensart"}
+          </p>
+        </div>
+
+        {/* Mode toggle */}
+        <div className="flex rounded-md border border-neutral-200 bg-neutral-50 p-0.5">
+          <button
+            onClick={() => setMode("wizard")}
+            className={`rounded px-3 py-1 text-xs font-medium transition-colors ${
+              mode === "wizard"
+                ? "bg-white text-neutral-900 shadow-sm"
+                : "text-neutral-500 hover:text-neutral-700"
+            }`}
+          >
+            Verfahren
+          </button>
+          <button
+            onClick={() => setMode("quick")}
+            className={`rounded px-3 py-1 text-xs font-medium transition-colors ${
+              mode === "quick"
+                ? "bg-white text-neutral-900 shadow-sm"
+                : "text-neutral-500 hover:text-neutral-700"
+            }`}
+          >
+            Schnell
+          </button>
+        </div>
       </div>
-      <DeadlineCalculator />
+
+      {mode === "wizard" ? <DeadlineWizard /> : <DeadlineCalculator />}
     </div>
   );
 }

frontend/src/components/deadlines/DeadlineWizard.tsx

@@ -0,0 +1,622 @@
+"use client";
+
+import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
+import { api } from "@/lib/api";
+import type {
+  ProceedingType,
+  TimelineResponse,
+  DetermineResponse,
+  TimelineEvent,
+  Case,
+} from "@/lib/types";
+import { format, parseISO, isPast, isThisWeek, isBefore, addDays } from "date-fns";
+import { de } from "date-fns/locale";
+import {
+  Scale,
+  Calendar,
+  ChevronRight,
+  ChevronDown,
+  GitBranch,
+  Check,
+  Clock,
+  AlertTriangle,
+  FileText,
+  Users,
+  Gavel,
+  ArrowRight,
+  RotateCcw,
+  Loader2,
+  CheckCircle2,
+  FolderOpen,
+} from "lucide-react";
+import { useState, useCallback, useMemo } from "react";
+import { toast } from "sonner";
+
+// --- Helpers ---
+
+function formatDuration(value: number, unit: string): string {
+  if (value === 0) return "";
+  const labels: Record<string, string> = {
+    days: value === 1 ? "Tag" : "Tage",
+    weeks: value === 1 ? "Woche" : "Wochen",
+    months: value === 1 ? "Monat" : "Monate",
+  };
+  return `${value} ${labels[unit] || unit}`;
+}
+
+function getPartyIcon(party?: string) {
+  switch (party) {
+    case "claimant":
+      return <Scale className="h-3.5 w-3.5" />;
+    case "defendant":
+      return <Users className="h-3.5 w-3.5" />;
+    case "court":
+      return <Gavel className="h-3.5 w-3.5" />;
+    default:
+      return <FileText className="h-3.5 w-3.5" />;
+  }
+}
+
+function getPartyLabel(party?: string): string {
+  switch (party) {
+    case "claimant":
+      return "Klaeger";
+    case "defendant":
+      return "Beklagter";
+    case "court":
+      return "Gericht";
+    case "both":
+      return "Beide Parteien";
+    default:
+      return "";
+  }
+}
+
+function getEventTypeLabel(type?: string): string {
+  switch (type) {
+    case "filing":
+      return "Einreichung";
+    case "hearing":
+      return "Verhandlung";
+    case "decision":
+      return "Entscheidung";
+    default:
+      return "";
+  }
+}
+
+type Urgency = "past" | "overdue" | "this_week" | "upcoming" | "future" | "none";
+
+function getUrgency(dateStr?: string): Urgency {
+  if (!dateStr) return "none";
+  const date = parseISO(dateStr);
+  const today = new Date();
+  today.setHours(0, 0, 0, 0);
+  if (isPast(date) && isBefore(date, today)) return "overdue";
+  if (isThisWeek(date, { weekStartsOn: 1 })) return "this_week";
+  if (isBefore(date, addDays(today, 30))) return "upcoming";
+  return "future";
+}
+
+const urgencyStyles: Record<Urgency, { dot: string; text: string; bg: string }> = {
+  past: { dot: "bg-neutral-400", text: "text-neutral-500", bg: "bg-neutral-50" },
+  overdue: { dot: "bg-red-500", text: "text-red-700", bg: "bg-red-50" },
+  this_week: { dot: "bg-amber-500", text: "text-amber-700", bg: "bg-amber-50" },
+  upcoming: { dot: "bg-blue-500", text: "text-blue-700", bg: "bg-blue-50" },
+  future: { dot: "bg-green-500", text: "text-green-700", bg: "bg-green-50" },
+  none: { dot: "bg-neutral-300", text: "text-neutral-500", bg: "bg-neutral-50" },
+};
+
+// --- Spawn Extraction ---
+
+function extractSpawns(events: TimelineEvent[]): TimelineEvent[] {
+  const spawns: TimelineEvent[] = [];
+  function walk(evts: TimelineEvent[]) {
+    for (const ev of evts) {
+      if (ev.is_spawn) spawns.push(ev);
+      if (ev.children) walk(ev.children);
+    }
+  }
+  walk(events);
+  return spawns;
+}
+
+// --- Flat timeline extraction ---
+
+function flattenTimeline(events: TimelineEvent[], depth = 0): (TimelineEvent & { depth: number })[] {
+  const result: (TimelineEvent & { depth: number })[] = [];
+  for (const ev of events) {
+    result.push({ ...ev, depth });
+    if (ev.children && ev.children.length > 0) {
+      result.push(...flattenTimeline(ev.children, depth + 1));
+    }
+  }
+  return result;
+}
+
+// --- Main Component ---
+
+export function DeadlineWizard() {
+  const [selectedType, setSelectedType] = useState<string>("");
+  const [triggerDate, setTriggerDate] = useState("");
+  const [conditions, setConditions] = useState<Record<string, boolean>>({});
+  const [selectedCaseId, setSelectedCaseId] = useState<string>("");
+  const [showBatchPanel, setShowBatchPanel] = useState(false);
+  const queryClient = useQueryClient();
+
+  // Fetch proceeding types
+  const { data: proceedingTypes, isLoading: typesLoading } = useQuery({
+    queryKey: ["proceeding-types"],
+    queryFn: () => api.get<ProceedingType[]>("/proceeding-types"),
+  });
+
+  // Fetch timeline structure when type is selected
+  const { data: timelineData } = useQuery({
+    queryKey: ["timeline", selectedType],
+    queryFn: () => api.get<TimelineResponse>(`/proceeding-types/${selectedType}/timeline`),
+    enabled: !!selectedType,
+  });
+
+  // Determine mutation
+  const determineMutation = useMutation({
+    mutationFn: (params: { proceeding_type: string; trigger_event_date: string; conditions: Record<string, boolean> }) =>
+      api.post<DetermineResponse>("/deadlines/determine", params),
+  });
+
+  // Cases for batch create
+  const { data: cases } = useQuery({
+    queryKey: ["cases"],
+    queryFn: () => api.get<Case[]>("/cases"),
+    enabled: showBatchPanel,
+  });
+
+  // Batch create mutation
+  const batchMutation = useMutation({
+    mutationFn: (params: { caseId: string; deadlines: { title: string; due_date: string; rule_code?: string }[] }) =>
+      api.post(`/cases/${params.caseId}/deadlines/batch`, { deadlines: params.deadlines }),
+    onSuccess: () => {
+      toast.success("Alle Fristen wurden auf die Akte uebernommen");
+      queryClient.invalidateQueries({ queryKey: ["deadlines"] });
+      setShowBatchPanel(false);
+    },
+    onError: () => {
+      toast.error("Fehler beim Erstellen der Fristen");
+    },
+  });
+
+  // Spawns from timeline structure (for condition toggles)
+  const spawns = useMemo(() => {
+    if (!timelineData?.timeline) return [];
+    return extractSpawns(timelineData.timeline);
+  }, [timelineData]);
+
+  // Calculate on type/date/condition change
+  const calculate = useCallback(() => {
+    if (!selectedType || !triggerDate) return;
+    determineMutation.mutate({
+      proceeding_type: selectedType,
+      trigger_event_date: triggerDate,
+      conditions,
+    });
+  }, [selectedType, triggerDate, conditions, determineMutation]);
+
+  // Auto-calculate when date or conditions change
+  const handleDateChange = (date: string) => {
+    setTriggerDate(date);
+    if (selectedType && date) {
+      determineMutation.mutate({
+        proceeding_type: selectedType,
+        trigger_event_date: date,
+        conditions,
+      });
+    }
+  };
+
+  const handleConditionToggle = (spawnId: string) => {
+    const next = { ...conditions, [spawnId]: !conditions[spawnId] };
+    setConditions(next);
+    if (selectedType && triggerDate) {
+      determineMutation.mutate({
+        proceeding_type: selectedType,
+        trigger_event_date: triggerDate,
+        conditions: next,
+      });
+    }
+  };
+
+  const handleTypeSelect = (code: string) => {
+    setSelectedType(code);
+    setConditions({});
+    if (triggerDate) {
+      // Will recalculate once timeline loads
+      determineMutation.reset();
+    }
+  };
+
+  const handleReset = () => {
+    setSelectedType("");
+    setTriggerDate("");
+    setConditions({});
+    setShowBatchPanel(false);
+    determineMutation.reset();
+  };
+
+  // Collect calculated deadlines for batch create
+  const collectDeadlines = (events: TimelineEvent[]): { title: string; due_date: string; rule_code?: string }[] => {
+    const result: { title: string; due_date: string; rule_code?: string }[] = [];
+    for (const ev of events) {
+      if (ev.date && ev.duration_value > 0) {
+        result.push({ title: ev.name, due_date: ev.date, rule_code: ev.rule_code || undefined });
+      }
+      if (ev.children) result.push(...collectDeadlines(ev.children));
+    }
+    return result;
+  };
+
+  const results = determineMutation.data;
+  const selectedPT = proceedingTypes?.find((pt) => pt.code === selectedType);
+
+  return (
+    <div className="space-y-5">
+      {/* Step 1: Proceeding Type Selection */}
+      <div className="rounded-lg border border-neutral-200 bg-white p-5">
+        <div className="flex items-center justify-between">
+          <div className="flex items-center gap-2 text-sm font-medium text-neutral-900">
+            <Scale className="h-4 w-4" />
+            Verfahrensart waehlen
+          </div>
+          {selectedType && (
+            <button
+              onClick={handleReset}
+              className="flex items-center gap-1 text-xs text-neutral-500 hover:text-neutral-700"
+            >
+              <RotateCcw className="h-3 w-3" />
+              Zuruecksetzen
+            </button>
+          )}
+        </div>
+
+        <div className="mt-4 grid grid-cols-2 gap-2 sm:grid-cols-3 lg:grid-cols-6">
+          {typesLoading ? (
+            <div className="col-span-full flex justify-center py-4">
+              <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+            </div>
+          ) : (
+            proceedingTypes?.map((pt) => (
+              <button
+                key={pt.id}
+                onClick={() => handleTypeSelect(pt.code)}
+                className={`rounded-lg border px-3 py-2.5 text-left transition-all ${
+                  selectedType === pt.code
+                    ? "border-neutral-900 bg-neutral-900 text-white shadow-sm"
+                    : "border-neutral-200 bg-white text-neutral-700 hover:border-neutral-400 hover:bg-neutral-50"
+                }`}
+              >
+                <div className="flex items-center gap-1.5">
+                  <div
+                    className="h-2 w-2 rounded-full"
+                    style={{ backgroundColor: pt.default_color }}
+                  />
+                  <span className="text-xs font-semibold">{pt.code}</span>
+                </div>
+                <div className="mt-1 text-xs leading-tight opacity-80">{pt.name}</div>
+              </button>
+            ))
+          )}
+        </div>
+      </div>
+
+      {/* Step 2: Date + Conditions */}
+      {selectedType && (
+        <div className="animate-fade-in rounded-lg border border-neutral-200 bg-white p-5">
+          <div className="flex items-center gap-2 text-sm font-medium text-neutral-900">
+            <Calendar className="h-4 w-4" />
+            Ausloesendes Ereignis
+          </div>
+
+          <div className="mt-4 flex flex-col gap-4 sm:flex-row sm:items-end">
+            <div className="flex-1">
+              <label className="mb-1 block text-xs font-medium text-neutral-500">
+                Datum des {selectedPT?.name || selectedType} (z.B. Klagezustellung)
+              </label>
+              <input
+                type="date"
+                value={triggerDate}
+                onChange={(e) => handleDateChange(e.target.value)}
+                className="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"
+              />
+            </div>
+
+            {/* Condition toggles */}
+            {spawns.length > 0 && (
+              <div className="flex flex-wrap gap-2">
+                {spawns.map((spawn) => (
+                  <button
+                    key={spawn.id}
+                    onClick={() => handleConditionToggle(spawn.id)}
+                    className={`flex items-center gap-1.5 rounded-full px-3 py-1.5 text-xs font-medium transition-all ${
+                      conditions[spawn.id]
+                        ? "bg-neutral-900 text-white"
+                        : "border border-neutral-300 bg-white text-neutral-600 hover:bg-neutral-50"
+                    }`}
+                  >
+                    <GitBranch className="h-3 w-3" />
+                    {spawn.spawn_label || spawn.name}
+                    {conditions[spawn.id] && <Check className="h-3 w-3" />}
+                  </button>
+                ))}
+              </div>
+            )}
+          </div>
+        </div>
+      )}
+
+      {/* Error */}
+      {determineMutation.isError && (
+        <div className="flex items-center gap-2 rounded-lg border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-700">
+          <AlertTriangle className="h-4 w-4 shrink-0" />
+          Fehler bei der Berechnung. Bitte Eingaben pruefen.
+        </div>
+      )}
+
+      {/* Step 3: Calculated Timeline */}
+      {results && results.timeline && (
+        <div className="animate-fade-in space-y-3">
+          {/* Header */}
+          <div className="flex items-center justify-between">
+            <div>
+              <h3 className="text-sm font-medium text-neutral-900">
+                Verfahrens-Timeline: {results.proceeding_name}
+              </h3>
+              <p className="mt-0.5 text-xs text-neutral-500">
+                {results.total_deadlines} Ereignisse ab{" "}
+                {format(parseISO(results.trigger_event_date), "dd. MMMM yyyy", { locale: de })}
+              </p>
+            </div>
+            <button
+              onClick={() => setShowBatchPanel(!showBatchPanel)}
+              className="flex items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-xs font-medium text-white transition-colors hover:bg-neutral-800"
+            >
+              <CheckCircle2 className="h-3.5 w-3.5" />
+              Alle uebernehmen
+            </button>
+          </div>
+
+          {/* Timeline visualization */}
+          <div className="rounded-lg border border-neutral-200 bg-white">
+            <TimelineTree events={results.timeline} conditions={conditions} depth={0} />
+          </div>
+
+          {/* Batch create panel */}
+          {showBatchPanel && (
+            <div className="animate-fade-in rounded-lg border border-neutral-200 bg-neutral-50 p-4">
+              <div className="flex items-center gap-2 text-sm font-medium text-neutral-900">
+                <FolderOpen className="h-4 w-4" />
+                Fristen auf Akte uebernehmen
+              </div>
+              <div className="mt-3 flex gap-3">
+                <select
+                  value={selectedCaseId}
+                  onChange={(e) => setSelectedCaseId(e.target.value)}
+                  className="flex-1 rounded-md border border-neutral-200 bg-white px-3 py-2 text-sm text-neutral-900 outline-none focus:border-neutral-400"
+                >
+                  <option value="">Akte waehlen...</option>
+                  {cases
+                    ?.filter((c) => c.status !== "closed")
+                    .map((c) => (
+                      <option key={c.id} value={c.id}>
+                        {c.case_number} — {c.title}
+                      </option>
+                    ))}
+                </select>
+                <button
+                  disabled={!selectedCaseId || batchMutation.isPending}
+                  onClick={() => {
+                    const deadlines = collectDeadlines(results.timeline);
+                    if (deadlines.length === 0) return;
+                    batchMutation.mutate({ caseId: selectedCaseId, deadlines });
+                  }}
+                  className="flex items-center gap-1.5 rounded-md bg-neutral-900 px-4 py-2 text-sm font-medium text-white transition-colors hover:bg-neutral-800 disabled:cursor-not-allowed disabled:opacity-50"
+                >
+                  {batchMutation.isPending ? (
+                    <Loader2 className="h-3.5 w-3.5 animate-spin" />
+                  ) : (
+                    <ArrowRight className="h-3.5 w-3.5" />
+                  )}
+                  {batchMutation.isPending ? "Erstelle..." : `${collectDeadlines(results.timeline).length} Fristen erstellen`}
+                </button>
+              </div>
+            </div>
+          )}
+        </div>
+      )}
+
+      {/* Empty state */}
+      {!results && !determineMutation.isPending && selectedType && triggerDate && (
+        <div className="flex items-center justify-center py-8">
+          <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+        </div>
+      )}
+
+      {!selectedType && (
+        <div className="flex flex-col items-center rounded-lg border border-dashed border-neutral-300 bg-white px-6 py-12 text-center">
+          <div className="rounded-xl bg-neutral-100 p-3">
+            <Scale className="h-6 w-6 text-neutral-400" />
+          </div>
+          <p className="mt-3 text-sm font-medium text-neutral-700">
+            UPC-Fristenbestimmung
+          </p>
+          <p className="mt-1 max-w-sm text-xs text-neutral-500">
+            Waehlen Sie die Verfahrensart und geben Sie das Datum des ausloesenden Ereignisses ein.
+            Alle Fristen des Verfahrens werden automatisch berechnet.
+          </p>
+        </div>
+      )}
+    </div>
+  );
+}
+
+// --- Timeline Tree Component ---
+
+function TimelineTree({
+  events,
+  conditions,
+  depth,
+}: {
+  events: TimelineEvent[];
+  conditions: Record<string, boolean>;
+  depth: number;
+}) {
+  return (
+    <>
+      {events.map((ev, i) => (
+        <TimelineNode
+          key={ev.id}
+          event={ev}
+          conditions={conditions}
+          depth={depth}
+          isLast={i === events.length - 1}
+        />
+      ))}
+    </>
+  );
+}
+
+function TimelineNode({
+  event: ev,
+  conditions,
+  depth,
+  isLast,
+}: {
+  event: TimelineEvent;
+  conditions: Record<string, boolean>;
+  depth: number;
+  isLast: boolean;
+}) {
+  const [expanded, setExpanded] = useState(true);
+
+  // Skip inactive spawns
+  if (ev.is_spawn && !conditions[ev.id]) return null;
+
+  const hasChildren = ev.children && ev.children.length > 0;
+  const visibleChildren = ev.children?.filter(
+    (c) => !c.is_spawn || conditions[c.id]
+  );
+  const hasVisibleChildren = visibleChildren && visibleChildren.length > 0;
+
+  const urgency = getUrgency(ev.date);
+  const styles = urgencyStyles[urgency];
+  const duration = formatDuration(ev.duration_value, ev.duration_unit);
+  const isConditional = ev.has_condition && ev.condition_rule_id;
+
+  return (
+    <>
+      <div
+        className={`group relative flex gap-3 px-4 py-3 transition-colors hover:bg-neutral-50 ${
+          !isLast && depth === 0 ? "border-b border-neutral-100" : ""
+        }`}
+        style={{ paddingLeft: `${16 + depth * 24}px` }}
+      >
+        {/* Timeline connector */}
+        <div className="flex flex-col items-center pt-1">
+          <div className={`h-3 w-3 shrink-0 rounded-full border-2 border-white shadow-sm ${styles.dot}`} />
+          {!isLast && <div className="mt-1 w-px flex-1 bg-neutral-200" />}
+        </div>
+
+        {/* Content */}
+        <div className="min-w-0 flex-1">
+          <div className="flex flex-col gap-1 sm:flex-row sm:items-start sm:justify-between sm:gap-2">
+            <div className="flex items-center gap-1.5">
+              {hasVisibleChildren && (
+                <button
+                  onClick={() => setExpanded(!expanded)}
+                  className="text-neutral-400 hover:text-neutral-600"
+                >
+                  {expanded ? (
+                    <ChevronDown className="h-3.5 w-3.5" />
+                  ) : (
+                    <ChevronRight className="h-3.5 w-3.5" />
+                  )}
+                </button>
+              )}
+              {ev.is_spawn && (
+                <GitBranch className="h-3.5 w-3.5 text-violet-500" />
+              )}
+              <span className="text-sm font-medium text-neutral-900">{ev.name}</span>
+              {!ev.is_mandatory && (
+                <span className="rounded bg-neutral-100 px-1 py-0.5 text-[10px] text-neutral-500">
+                  optional
+                </span>
+              )}
+            </div>
+
+            {/* Date */}
+            {ev.date && (
+              <div className="flex items-center gap-1.5 shrink-0">
+                {ev.was_adjusted && (
+                  <span className="text-[10px] text-amber-600" title={`Original: ${ev.original_date}`}>
+                    angepasst
+                  </span>
+                )}
+                <span className={`text-sm font-medium tabular-nums ${styles.text}`}>
+                  {format(parseISO(ev.date), "dd.MM.yyyy")}
+                </span>
+              </div>
+            )}
+          </div>
+
+          {/* Meta row */}
+          <div className="mt-0.5 flex flex-wrap items-center gap-x-2 gap-y-0.5 text-xs text-neutral-500">
+            {ev.primary_party && (
+              <span className="flex items-center gap-0.5">
+                {getPartyIcon(ev.primary_party)}
+                {getPartyLabel(ev.primary_party)}
+              </span>
+            )}
+            {ev.event_type && (
+              <>
+                <span className="text-neutral-300">·</span>
+                <span>{getEventTypeLabel(ev.event_type)}</span>
+              </>
+            )}
+            {duration && (
+              <>
+                <span className="text-neutral-300">·</span>
+                <span className="flex items-center gap-0.5">
+                  <Clock className="h-3 w-3" />
+                  {duration}
+                </span>
+              </>
+            )}
+            {ev.rule_code && (
+              <>
+                <span className="text-neutral-300">·</span>
+                <span className="rounded bg-neutral-100 px-1 py-0.5 font-mono text-[10px]">
+                  {ev.rule_code}
+                </span>
+              </>
+            )}
+            {isConditional && (
+              <>
+                <span className="text-neutral-300">·</span>
+                <span className="text-violet-600">
+                  bedingt{ev.alt_rule_code ? ` (${ev.alt_rule_code})` : ""}
+                </span>
+              </>
+            )}
+          </div>
+
+          {/* Notes */}
+          {ev.deadline_notes && (
+            <p className="mt-1 text-xs text-neutral-400 italic">{ev.deadline_notes}</p>
+          )}
+        </div>
+      </div>
+
+      {/* Children */}
+      {expanded && hasVisibleChildren && (
+        <TimelineTree events={visibleChildren!} conditions={conditions} depth={depth + 1} />
+      )}
+    </>
+  );
+}

frontend/src/components/layout/Header.tsx

@@ -2,6 +2,7 @@
 
 import { createClient } from "@/lib/supabase/client";
 import { TenantSwitcher } from "./TenantSwitcher";
+import { NotificationBell } from "@/components/notifications/NotificationBell";
 import { LogOut } from "lucide-react";
 import { useRouter } from "next/navigation";
 import { useEffect, useState } from "react";
@@ -29,6 +30,7 @@ export function Header() {
       <div className="w-8 lg:w-0" />
       <div className="flex items-center gap-2 sm:gap-3">
         <TenantSwitcher />
+        <NotificationBell />
         {email && (
           <span className="hidden text-sm text-neutral-500 sm:inline">
             {email}

frontend/src/components/notifications/NotificationBell.tsx

@@ -0,0 +1,205 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
+import { Bell, Check, CheckCheck, ExternalLink } from "lucide-react";
+import { api } from "@/lib/api";
+import type { Notification, NotificationListResponse } from "@/lib/types";
+
+function getEntityLink(n: Notification): string | null {
+  if (!n.entity_type || !n.entity_id) return null;
+  switch (n.entity_type) {
+    case "deadline":
+      return `/fristen/${n.entity_id}`;
+    case "appointment":
+      return `/termine/${n.entity_id}`;
+    case "case":
+      return `/akten/${n.entity_id}`;
+    default:
+      return null;
+  }
+}
+
+function getTypeColor(type: Notification["type"]): string {
+  switch (type) {
+    case "deadline_overdue":
+      return "bg-red-500";
+    case "deadline_reminder":
+      return "bg-amber-500";
+    case "case_update":
+      return "bg-blue-500";
+    case "assignment":
+      return "bg-violet-500";
+    default:
+      return "bg-neutral-500";
+  }
+}
+
+function timeAgo(dateStr: string): string {
+  const now = new Date();
+  const date = new Date(dateStr);
+  const diffMs = now.getTime() - date.getTime();
+  const diffMin = Math.floor(diffMs / 60000);
+  if (diffMin < 1) return "gerade eben";
+  if (diffMin < 60) return `vor ${diffMin} Min.`;
+  const diffHours = Math.floor(diffMin / 60);
+  if (diffHours < 24) return `vor ${diffHours} Std.`;
+  const diffDays = Math.floor(diffHours / 24);
+  if (diffDays === 1) return "gestern";
+  return `vor ${diffDays} Tagen`;
+}
+
+export function NotificationBell() {
+  const [open, setOpen] = useState(false);
+  const panelRef = useRef<HTMLDivElement>(null);
+  const queryClient = useQueryClient();
+
+  const { data: unreadData } = useQuery({
+    queryKey: ["notifications-unread-count"],
+    queryFn: () =>
+      api.get<{ unread_count: number }>("/api/notifications/unread-count"),
+    refetchInterval: 30_000,
+  });
+
+  const { data: notifData } = useQuery({
+    queryKey: ["notifications"],
+    queryFn: () =>
+      api.get<NotificationListResponse>("/api/notifications?limit=20"),
+    enabled: open,
+  });
+
+  const markRead = useMutation({
+    mutationFn: (id: string) =>
+      api.patch(`/api/notifications/${id}/read`),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["notifications"] });
+      queryClient.invalidateQueries({
+        queryKey: ["notifications-unread-count"],
+      });
+    },
+  });
+
+  const markAllRead = useMutation({
+    mutationFn: () => api.patch("/api/notifications/read-all"),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["notifications"] });
+      queryClient.invalidateQueries({
+        queryKey: ["notifications-unread-count"],
+      });
+    },
+  });
+
+  // Close on click outside
+  useEffect(() => {
+    function handleClickOutside(e: MouseEvent) {
+      if (panelRef.current && !panelRef.current.contains(e.target as Node)) {
+        setOpen(false);
+      }
+    }
+    if (open) {
+      document.addEventListener("mousedown", handleClickOutside);
+    }
+    return () => document.removeEventListener("mousedown", handleClickOutside);
+  }, [open]);
+
+  const unreadCount = unreadData?.unread_count ?? 0;
+  const notifications = notifData?.data ?? [];
+
+  return (
+    <div className="relative" ref={panelRef}>
+      <button
+        onClick={() => setOpen(!open)}
+        className="relative rounded-md p-1.5 text-neutral-400 transition-colors hover:bg-neutral-100 hover:text-neutral-600"
+        title="Benachrichtigungen"
+      >
+        <Bell className="h-4 w-4" />
+        {unreadCount > 0 && (
+          <span className="absolute -right-0.5 -top-0.5 flex h-4 min-w-4 items-center justify-center rounded-full bg-red-500 px-1 text-[10px] font-bold text-white">
+            {unreadCount > 99 ? "99+" : unreadCount}
+          </span>
+        )}
+      </button>
+
+      {open && (
+        <div className="absolute right-0 top-full z-50 mt-2 w-80 rounded-xl border border-neutral-200 bg-white shadow-lg sm:w-96">
+          {/* Header */}
+          <div className="flex items-center justify-between border-b border-neutral-100 px-4 py-3">
+            <h3 className="text-sm font-semibold text-neutral-900">
+              Benachrichtigungen
+            </h3>
+            {unreadCount > 0 && (
+              <button
+                onClick={() => markAllRead.mutate()}
+                className="flex items-center gap-1 text-xs text-neutral-500 hover:text-neutral-700"
+              >
+                <CheckCheck className="h-3 w-3" />
+                Alle gelesen
+              </button>
+            )}
+          </div>
+
+          {/* Notification list */}
+          <div className="max-h-96 overflow-y-auto">
+            {notifications.length === 0 ? (
+              <div className="p-6 text-center text-sm text-neutral-400">
+                Keine Benachrichtigungen
+              </div>
+            ) : (
+              notifications.map((n) => {
+                const link = getEntityLink(n);
+                return (
+                  <div
+                    key={n.id}
+                    className={`flex items-start gap-3 border-b border-neutral-50 px-4 py-3 transition-colors last:border-0 ${
+                      n.read_at
+                        ? "bg-white"
+                        : "bg-blue-50/50"
+                    }`}
+                  >
+                    <div
+                      className={`mt-1.5 h-2 w-2 flex-shrink-0 rounded-full ${getTypeColor(n.type)}`}
+                    />
+                    <div className="min-w-0 flex-1">
+                      <p className="text-sm font-medium text-neutral-900 leading-snug">
+                        {n.title}
+                      </p>
+                      {n.body && (
+                        <p className="mt-0.5 text-xs text-neutral-500 line-clamp-2">
+                          {n.body}
+                        </p>
+                      )}
+                      <div className="mt-1.5 flex items-center gap-2">
+                        <span className="text-[11px] text-neutral-400">
+                          {timeAgo(n.created_at)}
+                        </span>
+                        {link && (
+                          <a
+                            href={link}
+                            onClick={() => setOpen(false)}
+                            className="flex items-center gap-0.5 text-[11px] text-blue-600 hover:text-blue-700"
+                          >
+                            <ExternalLink className="h-2.5 w-2.5" />
+                            Anzeigen
+                          </a>
+                        )}
+                      </div>
+                    </div>
+                    {!n.read_at && (
+                      <button
+                        onClick={() => markRead.mutate(n.id)}
+                        className="flex-shrink-0 rounded p-1 text-neutral-400 hover:bg-neutral-100 hover:text-neutral-600"
+                        title="Als gelesen markieren"
+                      >
+                        <Check className="h-3 w-3" />
+                      </button>
+                    )}
+                  </div>
+                );
+              })
+            )}
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}

frontend/src/components/settings/NotificationSettings.tsx

@@ -0,0 +1,167 @@
+"use client";
+
+import { useState } from "react";
+import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
+import { api } from "@/lib/api";
+import type { NotificationPreferences } from "@/lib/types";
+
+const REMINDER_OPTIONS = [
+  { value: 14, label: "14 Tage" },
+  { value: 7, label: "7 Tage" },
+  { value: 3, label: "3 Tage" },
+  { value: 1, label: "1 Tag" },
+];
+
+export function NotificationSettings() {
+  const queryClient = useQueryClient();
+  const [saved, setSaved] = useState(false);
+
+  const { data: prefs, isLoading } = useQuery({
+    queryKey: ["notification-preferences"],
+    queryFn: () =>
+      api.get<NotificationPreferences>("/api/notification-preferences"),
+  });
+
+  const [reminderDays, setReminderDays] = useState<number[]>([]);
+  const [emailEnabled, setEmailEnabled] = useState(true);
+  const [dailyDigest, setDailyDigest] = useState(false);
+  const [initialized, setInitialized] = useState(false);
+
+  // Sync state from server once loaded
+  if (prefs && !initialized) {
+    setReminderDays(prefs.deadline_reminder_days);
+    setEmailEnabled(prefs.email_enabled);
+    setDailyDigest(prefs.daily_digest);
+    setInitialized(true);
+  }
+
+  const update = useMutation({
+    mutationFn: (input: {
+      deadline_reminder_days: number[];
+      email_enabled: boolean;
+      daily_digest: boolean;
+    }) => api.put<NotificationPreferences>("/api/notification-preferences", input),
+    onSuccess: () => {
+      queryClient.invalidateQueries({
+        queryKey: ["notification-preferences"],
+      });
+      setSaved(true);
+      setTimeout(() => setSaved(false), 2000);
+    },
+  });
+
+  function toggleDay(day: number) {
+    setReminderDays((prev) =>
+      prev.includes(day) ? prev.filter((d) => d !== day) : [...prev, day].sort((a, b) => b - a),
+    );
+  }
+
+  function handleSave() {
+    update.mutate({
+      deadline_reminder_days: reminderDays,
+      email_enabled: emailEnabled,
+      daily_digest: dailyDigest,
+    });
+  }
+
+  if (isLoading) {
+    return (
+      <div className="animate-pulse space-y-3">
+        <div className="h-4 w-48 rounded bg-neutral-200" />
+        <div className="h-8 w-full rounded bg-neutral-100" />
+        <div className="h-8 w-full rounded bg-neutral-100" />
+      </div>
+    );
+  }
+
+  return (
+    <div className="space-y-5">
+      {/* Reminder days */}
+      <div>
+        <p className="text-sm font-medium text-neutral-700">
+          Fristen-Erinnerungen
+        </p>
+        <p className="mt-0.5 text-xs text-neutral-500">
+          Erinnern Sie mich vor Fristablauf:
+        </p>
+        <div className="mt-2 flex flex-wrap gap-2">
+          {REMINDER_OPTIONS.map((opt) => (
+            <button
+              key={opt.value}
+              onClick={() => toggleDay(opt.value)}
+              className={`rounded-lg border px-3 py-1.5 text-sm transition-colors ${
+                reminderDays.includes(opt.value)
+                  ? "border-blue-500 bg-blue-50 text-blue-700"
+                  : "border-neutral-200 bg-white text-neutral-600 hover:border-neutral-300"
+              }`}
+            >
+              {opt.label}
+            </button>
+          ))}
+        </div>
+      </div>
+
+      {/* Email toggle */}
+      <label className="flex items-center justify-between">
+        <div>
+          <p className="text-sm font-medium text-neutral-700">
+            E-Mail-Benachrichtigungen
+          </p>
+          <p className="text-xs text-neutral-500">
+            Erinnerungen per E-Mail erhalten
+          </p>
+        </div>
+        <button
+          onClick={() => setEmailEnabled(!emailEnabled)}
+          className={`relative h-6 w-11 rounded-full transition-colors ${
+            emailEnabled ? "bg-blue-500" : "bg-neutral-300"
+          }`}
+        >
+          <span
+            className={`absolute left-0.5 top-0.5 h-5 w-5 rounded-full bg-white shadow transition-transform ${
+              emailEnabled ? "translate-x-5" : "translate-x-0"
+            }`}
+          />
+        </button>
+      </label>
+
+      {/* Daily digest toggle */}
+      <label className="flex items-center justify-between">
+        <div>
+          <p className="text-sm font-medium text-neutral-700">
+            Tagesübersicht
+          </p>
+          <p className="text-xs text-neutral-500">
+            Alle Benachrichtigungen gesammelt um 8:00 Uhr per E-Mail
+          </p>
+        </div>
+        <button
+          onClick={() => setDailyDigest(!dailyDigest)}
+          className={`relative h-6 w-11 rounded-full transition-colors ${
+            dailyDigest ? "bg-blue-500" : "bg-neutral-300"
+          }`}
+        >
+          <span
+            className={`absolute left-0.5 top-0.5 h-5 w-5 rounded-full bg-white shadow transition-transform ${
+              dailyDigest ? "translate-x-5" : "translate-x-0"
+            }`}
+          />
+        </button>
+      </label>
+
+      {/* Save */}
+      <div className="flex items-center gap-3 pt-2">
+        <button
+          onClick={handleSave}
+          disabled={update.isPending}
+          className="rounded-md bg-neutral-900 px-4 py-2 text-sm font-medium text-white hover:bg-neutral-800 disabled:opacity-50"
+        >
+          {update.isPending ? "Speichern..." : "Speichern"}
+        </button>
+        {saved && (
+          <span className="text-sm text-green-600">Gespeichert</span>
+        )}
+      </div>
+    </div>
+  );
+}

frontend/src/lib/types.ts

@@ -120,12 +120,76 @@ export interface DeadlineRule {
   rule_code?: string;
   deadline_notes?: string;
   sequence_order: number;
+  condition_rule_id?: string;
+  alt_duration_value?: number;
+  alt_duration_unit?: string;
+  alt_rule_code?: string;
+  is_spawn?: boolean;
+  spawn_label?: string;
 }
 
 export interface RuleTreeNode extends DeadlineRule {
   children?: RuleTreeNode[];
 }
 
+// Timeline determination types
+
+export interface TimelineEvent {
+  id: string;
+  code?: string;
+  name: string;
+  description?: string;
+  primary_party?: string;
+  event_type?: string;
+  is_mandatory: boolean;
+  duration_value: number;
+  duration_unit: string;
+  rule_code?: string;
+  deadline_notes?: string;
+  is_spawn: boolean;
+  spawn_label?: string;
+  has_condition: boolean;
+  condition_rule_id?: string;
+  alt_rule_code?: string;
+  alt_duration_value?: number;
+  alt_duration_unit?: string;
+  date?: string;
+  original_date?: string;
+  was_adjusted: boolean;
+  children?: TimelineEvent[];
+}
+
+export interface TimelineResponse {
+  proceeding_type: ProceedingType;
+  timeline: TimelineEvent[];
+}
+
+export interface DetermineRequest {
+  proceeding_type: string;
+  trigger_event_date: string;
+  conditions: Record<string, boolean>;
+}
+
+export interface DetermineResponse {
+  proceeding_type: string;
+  proceeding_name: string;
+  proceeding_color: string;
+  trigger_event_date: string;
+  timeline: TimelineEvent[];
+  total_deadlines: number;
+}
+
+export interface BatchCreateRequest {
+  deadlines: {
+    title: string;
+    due_date: string;
+    original_due_date?: string;
+    rule_id?: string;
+    rule_code?: string;
+    notes?: string;
+  }[];
+}
+
 export interface ProceedingType {
   id: number;
   code: string;