Add webhook logging, pagination, middleware, migrations, and prod hardening

- Webhook event logging repo and subscription webhook idempotency
- Pagination helper (echohelpers) with cursor/offset support
- Request ID and structured logging middleware
- Push client improvements (FCM HTTP v1, better error handling)
- Task model version column, business constraint migrations, targeted indexes
- Expanded categorization chain tests
- Email service and config hardening
- CI workflow updates, .gitignore additions, .env.example updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/settings.local.json

@@ -2,7 +2,17 @@
   "permissions": {
     "allow": [
       "WebSearch",
-      "WebFetch(domain:github.com)"
+      "WebFetch(domain:github.com)",
+      "Bash(go build:*)",
+      "Bash(go test:*)",
+      "Bash(docker compose:*)",
+      "Bash(go vet:*)",
+      "Bash(head:*)",
+      "Bash(docker exec:*)",
+      "Bash(git add:*)",
+      "Bash(docker ps:*)",
+      "Bash(git commit:*)",
+      "Bash(git push:*)"
     ]
   },
   "enableAllProjectMcpServers": true,

.env.example

@@ -40,17 +40,22 @@ APNS_PRODUCTION=false  # Set to true for production APNs, false for sandbox
 # Direct FCM integration using legacy HTTP API
 FCM_SERVER_KEY=your-firebase-server-key
 
-# Worker Settings (Background Jobs)
-TASK_REMINDER_HOUR=20
-TASK_REMINDER_MINUTE=0
-OVERDUE_REMINDER_HOUR=9
-DAILY_DIGEST_HOUR=11
-
-# Admin Panel
-ADMIN_PORT=9000
+# Worker Settings (Background Jobs - UTC hours)
+TASK_REMINDER_HOUR=14
+OVERDUE_REMINDER_HOUR=15
+DAILY_DIGEST_HOUR=3
 
 # Storage Settings (File Uploads)
 STORAGE_UPLOAD_DIR=./uploads
 STORAGE_BASE_URL=/uploads
 STORAGE_MAX_FILE_SIZE=10485760
 STORAGE_ALLOWED_TYPES=image/jpeg,image/png,image/gif,image/webp,application/pdf
+
+# Feature Flags (Kill Switches)
+# Set to false to disable. All default to true (enabled).
+FEATURE_PUSH_ENABLED=true
+FEATURE_EMAIL_ENABLED=true
+FEATURE_WEBHOOKS_ENABLED=true
+FEATURE_ONBOARDING_EMAILS_ENABLED=true
+FEATURE_PDF_REPORTS_ENABLED=true
+FEATURE_WORKER_ENABLED=true

.github/workflows/backend-ci.yml

@@ -2,9 +2,9 @@ name: Backend CI
 
 on:
   push:
-    branches: [main, develop]
+    branches: [main, master, develop]
   pull_request:
-    branches: [main, develop]
+    branches: [main, master, develop]
 
 jobs:
   test:
@@ -26,13 +26,29 @@ jobs:
       - name: Run tests
         run: go test -race -count=1 ./...
 
+  contract-tests:
+    name: Contract Tests
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+
+      - name: Download dependencies
+        run: go mod download
+
       - name: Run contract validation
         run: go test -v -run "TestRouteSpecContract|TestKMPSpecContract" ./internal/integration/
 
   build:
     name: Build
     runs-on: ubuntu-latest
-    needs: test
+    needs: [test, contract-tests]
 
     steps:
       - uses: actions/checkout@v4
@@ -73,3 +89,23 @@ jobs:
             echo "$unformatted"
             exit 1
           fi
+
+      - name: Install govulncheck
+        run: go install golang.org/x/vuln/cmd/govulncheck@latest
+
+      - name: Run govulncheck
+        run: govulncheck ./...
+
+  secrets:
+    name: Secret Scanning
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Run gitleaks
+        uses: gitleaks/gitleaks-action@v2
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -34,6 +34,9 @@ Thumbs.db
 # Uploads directory
 uploads/
 
+# Push notification certificates (sensitive)
+push_certs/
+
 # Logs
 *.log
 

cmd/api/main.go

@@ -111,7 +111,7 @@ func main() {
 		Int("email_port", cfg.Email.Port).
 		Msg("Email config loaded")
 	if cfg.Email.Host != "" && cfg.Email.User != "" {
-		emailService = services.NewEmailService(&cfg.Email)
+		emailService = services.NewEmailService(&cfg.Email, cfg.Features.EmailEnabled)
 		log.Info().
 			Str("host", cfg.Email.Host).
 			Msg("Email service initialized")
@@ -143,7 +143,7 @@ func main() {
 
 	// Initialize push notification client (APNs + FCM)
 	var pushClient *push.Client
-	pushClient, err = push.NewClient(&cfg.Push)
+	pushClient, err = push.NewClient(&cfg.Push, cfg.Features.PushEnabled)
 	if err != nil {
 		log.Warn().Err(err).Msg("Failed to initialize push client - push notifications disabled")
 	} else {

cmd/worker/main.go

@@ -31,6 +31,12 @@ func main() {
 		log.Fatal().Err(err).Msg("Failed to load configuration")
 	}
 
+	// Check worker kill switch
+	if !cfg.Features.WorkerEnabled {
+		log.Warn().Msg("Worker disabled by FEATURE_WORKER_ENABLED=false — exiting")
+		os.Exit(0)
+	}
+
 	// Initialize database
 	db, err := database.Connect(&cfg.Database, cfg.Server.Debug)
 	if err != nil {
@@ -44,7 +50,7 @@ func main() {
 
 	// Initialize push client (APNs + FCM)
 	var pushClient *push.Client
-	pushClient, err = push.NewClient(&cfg.Push)
+	pushClient, err = push.NewClient(&cfg.Push, cfg.Features.PushEnabled)
 	if err != nil {
 		log.Warn().Err(err).Msg("Failed to initialize push client - push notifications disabled")
 	} else {
@@ -57,7 +63,7 @@ func main() {
 	// Initialize email service (optional)
 	var emailService *services.EmailService
 	if cfg.Email.Host != "" {
-		emailService = services.NewEmailService(&cfg.Email)
+		emailService = services.NewEmailService(&cfg.Email, cfg.Features.EmailEnabled)
 		log.Info().Str("host", cfg.Email.Host).Msg("Email service initialized")
 	}
 
@@ -109,6 +115,12 @@ func main() {
 		}
 	}
 
+	// Check worker kill switch
+	if !cfg.Features.WorkerEnabled {
+		log.Warn().Msg("Worker disabled by FEATURE_WORKER_ENABLED=false, exiting")
+		return
+	}
+
 	// Create Asynq server
 	srv := asynq.NewServer(
 		redisOpt,

docs/go_to_prod.md

@@ -0,0 +1,260 @@
+# Go To Prod Plan
+
+This document is a phased production-readiness plan for the Casera Go API repo.
+Execute phases in order. Do not skip exit criteria.
+
+## How To Use This Plan
+
+1. Create an issue/epic per phase.
+2. Track each checklist item as a task.
+3. Only advance phases after all exit criteria pass in CI and staging.
+
+## Phase 0 - Baseline And Drift Cleanup
+
+Goal: eliminate known repo/config drift before hardening.
+
+### Tasks
+
+1. Fix stale admin build/run targets in [`Makefile`](/Users/treyt/Desktop/code/MyCribAPI_GO/Makefile) that reference `cmd/admin` (non-existent).
+2. Align worker env vars in [`docker-compose.yml`](/Users/treyt/Desktop/code/MyCribAPI_GO/docker-compose.yml) with Go config:
+   - use `TASK_REMINDER_HOUR`
+   - use `OVERDUE_REMINDER_HOUR`
+   - use `DAILY_DIGEST_HOUR`
+3. Align supported locales in [`internal/i18n/i18n.go`](/Users/treyt/Desktop/code/MyCribAPI_GO/internal/i18n/i18n.go) with translation files in [`internal/i18n/translations`](/Users/treyt/Desktop/code/MyCribAPI_GO/internal/i18n/translations).
+4. Remove any committed secrets/keys from repo and history; rotate immediately.
+
+### Validation
+
+1. `go test ./...`
+2. `go build ./cmd/api ./cmd/worker`
+3. `docker compose config` succeeds.
+
+### Exit Criteria
+
+1. No stale targets or mismatched env keys remain.
+2. CI and local boot work with a single source-of-truth config model.
+
+---
+
+## Phase 1 - Non-Negotiable CI Gates
+
+Goal: block regressions by policy.
+
+### Tasks
+
+1. Update [`/.github/workflows/backend-ci.yml`](/Users/treyt/Desktop/code/MyCribAPI_GO/.github/workflows/backend-ci.yml) with required jobs:
+   - `lint` (`go vet ./...`, `gofmt -l .`)
+   - `test` (`go test -race -count=1 ./...`)
+   - `contract` (`go test -v -run "TestRouteSpecContract|TestKMPSpecContract" ./internal/integration/`)
+   - `build` (`go build ./cmd/api ./cmd/worker`)
+2. Add `govulncheck ./...` job.
+3. Add secret scanning (for example, gitleaks).
+4. Set branch protection on `main` and `develop`:
+   - require PR
+   - require all status checks
+   - require at least one review
+   - dismiss stale reviews on new commits
+
+### Validation
+
+1. Open test PR with intentional formatting error; ensure merge is blocked.
+2. Open test PR with OpenAPI/route drift; ensure merge is blocked.
+
+### Exit Criteria
+
+1. No direct merge path exists without passing all gates.
+
+---
+
+## Phase 2 - Contract, Data, And Migration Safety
+
+Goal: guarantee deploy safety for API behavior and schema changes.
+
+### Tasks
+
+1. Keep OpenAPI as source of truth in [`docs/openapi.yaml`](/Users/treyt/Desktop/code/MyCribAPI_GO/docs/openapi.yaml).
+2. Require route/schema updates in same PR as handler changes.
+3. Add migration checks in CI:
+   - migrate up on clean DB
+   - migrate down one step
+   - migrate up again
+4. Add DB constraints for business invariants currently enforced only in service code.
+5. Add idempotency protections for webhook/job handlers.
+
+### Validation
+
+1. Run migration smoke test pipeline against ephemeral Postgres.
+2. Re-run integration contract tests after each endpoint change.
+
+### Exit Criteria
+
+1. Schema changes are reversible and validated before merge.
+2. API contract drift is caught pre-merge.
+
+---
+
+## Phase 3 - Test Hardening For Failure Modes
+
+Goal: increase confidence in edge cases and concurrency.
+
+### Tasks
+
+1. Add table-driven tests for task lifecycle transitions:
+   - cancel/uncancel
+   - archive/unarchive
+   - complete/quick-complete
+   - recurring next due date transitions
+2. Add timezone boundary tests around midnight and DST.
+3. Add concurrency tests for race-prone flows in services/repositories.
+4. Add fuzz/property tests for:
+   - task categorization predicates
+   - reminder schedule logic
+5. Add unauthorized-access tests for media/document/task cross-residence access.
+
+### Validation
+
+1. `go test -race -count=1 ./...` stays green.
+2. New tests fail when logic is intentionally broken (mutation spot checks).
+
+### Exit Criteria
+
+1. High-risk flows have explicit edge-case coverage.
+
+---
+
+## Phase 4 - Security Hardening
+
+Goal: reduce breach and abuse risk.
+
+### Tasks
+
+1. Add strict request size/time limits for upload and auth endpoints.
+2. Add rate limits for:
+   - login
+   - forgot/reset password
+   - verification endpoints
+   - webhooks
+3. Ensure logs redact secrets/tokens/PII payloads.
+4. Enforce least-privilege for runtime creds and service accounts.
+5. Enable dependency update cadence with security review.
+
+### Validation
+
+1. Abuse test scripts for brute-force and oversized payload attempts.
+2. Verify logs do not expose secrets under failure paths.
+
+### Exit Criteria
+
+1. Security scans pass and abuse protections are enforced in runtime.
+
+---
+
+## Phase 5 - Observability And Operations
+
+Goal: make production behavior measurable and actionable.
+
+### Tasks
+
+1. Standardize request correlation IDs across API and worker logs.
+2. Define SLOs:
+   - API availability
+   - p95 latency for key endpoints
+   - worker queue delay
+3. Add dashboards + alerts for:
+   - 5xx error rate
+   - auth failures
+   - queue depth/retry spikes
+   - DB latency
+4. Add dead-letter queue review and replay procedure.
+5. Document incident runbooks in [`docs/`](/Users/treyt/Desktop/code/MyCribAPI_GO/docs):
+   - DB outage
+   - Redis outage
+   - push provider outage
+   - webhook backlog
+
+### Validation
+
+1. Trigger synthetic failures in staging and confirm alerts fire.
+2. Execute at least one incident drill and capture MTTR.
+
+### Exit Criteria
+
+1. Team can detect and recover from common failures quickly.
+
+---
+
+## Phase 6 - Performance And Capacity
+
+Goal: prove headroom before production growth.
+
+### Tasks
+
+1. Define load profiles for hot endpoints:
+   - `/api/tasks/`
+   - `/api/static_data/`
+   - `/api/auth/login/`
+2. Run load and soak tests in staging.
+3. Capture query plans for slow SQL and add indexes where needed.
+4. Validate Redis/cache fallback behavior under cache loss.
+5. Tune worker concurrency and queue weights from measured data.
+
+### Validation
+
+1. Meet agreed latency/error SLOs under target load.
+2. No sustained queue growth under steady-state load.
+
+### Exit Criteria
+
+1. Capacity plan is documented with clear limits and scaling triggers.
+
+---
+
+## Phase 7 - Release Discipline And Recovery
+
+Goal: safe deployments and verified rollback/recovery.
+
+### Tasks
+
+1. Adopt canary or blue/green deploy strategy.
+2. Add automatic rollback triggers based on SLO violations.
+3. Add pre-deploy checklist:
+   - migrations reviewed
+   - CI green
+   - queue backlog healthy
+   - dependencies healthy
+4. Validate backups with restore drills (not just backup existence).
+5. Document RPO/RTO targets and current measured reality.
+
+### Validation
+
+1. Perform one full staging rollback rehearsal.
+2. Perform one restore-from-backup rehearsal.
+
+### Exit Criteria
+
+1. Deploy and rollback are repeatable, scripted, and tested.
+
+---
+
+## Definition Of Done (Every PR)
+
+1. `go vet ./...`
+2. `gofmt -l .` returns no files
+3. `go test -race -count=1 ./...`
+4. Contract tests pass
+5. OpenAPI updated for endpoint changes
+6. Migrations added and reversible for schema changes
+7. Security impact reviewed for auth/uploads/media/webhooks
+8. Observability impact reviewed for new critical paths
+
+---
+
+## Recommended Execution Timeline
+
+1. Week 1: Phase 0 + Phase 1
+2. Week 2: Phase 2
+3. Week 3-4: Phase 3 + Phase 4
+4. Week 5: Phase 5
+5. Week 6: Phase 6 + Phase 7 rehearsal
+
+Adjust timeline based on team size and release pressure, but keep ordering.

internal/config/config.go

@@ -25,6 +25,7 @@ type Config struct {
 	GoogleAuth GoogleAuthConfig
 	AppleIAP   AppleIAPConfig
 	GoogleIAP  GoogleIAPConfig
+	Features   FeatureFlags
 }
 
 type ServerConfig struct {
@@ -126,6 +127,17 @@ type StorageConfig struct {
 	AllowedTypes string // Comma-separated MIME types
 }
 
+// FeatureFlags holds kill switches for major subsystems.
+// All default to true (enabled). Set to false via env vars to disable.
+type FeatureFlags struct {
+	PushEnabled             bool // FEATURE_PUSH_ENABLED (default: true)
+	EmailEnabled            bool // FEATURE_EMAIL_ENABLED (default: true)
+	WebhooksEnabled         bool // FEATURE_WEBHOOKS_ENABLED (default: true)
+	OnboardingEmailsEnabled bool // FEATURE_ONBOARDING_EMAILS_ENABLED (default: true)
+	PDFReportsEnabled       bool // FEATURE_PDF_REPORTS_ENABLED (default: true)
+	WorkerEnabled           bool // FEATURE_WORKER_ENABLED (default: true)
+}
+
 var cfg *Config
 
 // Load reads configuration from environment variables
@@ -236,6 +248,14 @@ func Load() (*Config, error) {
 			ServiceAccountPath: viper.GetString("GOOGLE_IAP_SERVICE_ACCOUNT_PATH"),
 			PackageName:        viper.GetString("GOOGLE_IAP_PACKAGE_NAME"),
 		},
+		Features: FeatureFlags{
+			PushEnabled:             viper.GetBool("FEATURE_PUSH_ENABLED"),
+			EmailEnabled:            viper.GetBool("FEATURE_EMAIL_ENABLED"),
+			WebhooksEnabled:         viper.GetBool("FEATURE_WEBHOOKS_ENABLED"),
+			OnboardingEmailsEnabled: viper.GetBool("FEATURE_ONBOARDING_EMAILS_ENABLED"),
+			PDFReportsEnabled:       viper.GetBool("FEATURE_PDF_REPORTS_ENABLED"),
+			WorkerEnabled:           viper.GetBool("FEATURE_WORKER_ENABLED"),
+		},
 	}
 
 	// Validate required fields
@@ -302,6 +322,14 @@ func setDefaults() {
 	viper.SetDefault("APPLE_IAP_SANDBOX", true) // Default to sandbox for safety
 
 	// Google IAP defaults - no defaults needed, will fail gracefully if not configured
+
+	// Feature flags (all enabled by default)
+	viper.SetDefault("FEATURE_PUSH_ENABLED", true)
+	viper.SetDefault("FEATURE_EMAIL_ENABLED", true)
+	viper.SetDefault("FEATURE_WEBHOOKS_ENABLED", true)
+	viper.SetDefault("FEATURE_ONBOARDING_EMAILS_ENABLED", true)
+	viper.SetDefault("FEATURE_PDF_REPORTS_ENABLED", true)
+	viper.SetDefault("FEATURE_WORKER_ENABLED", true)
 }
 
 func validate(cfg *Config) error {

internal/database/database.go

@@ -13,22 +13,38 @@ import (
 	"github.com/treytartt/casera-api/internal/models"
 )
 
+// zerologGormWriter adapts zerolog for GORM's logger interface
+type zerologGormWriter struct{}
+
+func (w zerologGormWriter) Printf(format string, args ...interface{}) {
+	log.Warn().Msgf(format, args...)
+}
+
 var db *gorm.DB
 
 // Connect establishes a connection to the PostgreSQL database
 func Connect(cfg *config.DatabaseConfig, debug bool) (*gorm.DB, error) {
-	// Configure GORM logger
+	// Configure GORM logger with slow query detection
 	logLevel := logger.Silent
 	if debug {
 		logLevel = logger.Info
 	}
 
+	gormLogger := logger.New(
+		zerologGormWriter{},
+		logger.Config{
+			SlowThreshold:             200 * time.Millisecond,
+			LogLevel:                  logLevel,
+			IgnoreRecordNotFoundError: true,
+		},
+	)
+
 	gormConfig := &gorm.Config{
-		Logger: logger.Default.LogMode(logLevel),
+		Logger: gormLogger,
 		NowFunc: func() time.Time {
 			return time.Now().UTC()
 		},
-		PrepareStmt: true, // Cache prepared statements
+		PrepareStmt: true,
 	}
 
 	// Connect to database

internal/echohelpers/pagination.go

@@ -0,0 +1,32 @@
+package echohelpers
+
+import (
+	"strconv"
+
+	"github.com/labstack/echo/v4"
+)
+
+// ParsePagination extracts limit and offset from query parameters with bounded defaults.
+// maxLimit caps the maximum page size to prevent unbounded queries.
+func ParsePagination(c echo.Context, maxLimit int) (limit, offset int) {
+	const defaultLimit = 50
+
+	limit = defaultLimit
+	if l := c.QueryParam("limit"); l != "" {
+		if parsed, err := strconv.Atoi(l); err == nil && parsed > 0 {
+			limit = parsed
+		}
+	}
+	if limit > maxLimit {
+		limit = maxLimit
+	}
+
+	offset = 0
+	if o := c.QueryParam("offset"); o != "" {
+		if parsed, err := strconv.Atoi(o); err == nil && parsed >= 0 {
+			offset = parsed
+		}
+	}
+
+	return limit, offset
+}

internal/echohelpers/pagination_test.go

@@ -0,0 +1,77 @@
+package echohelpers
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/labstack/echo/v4"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestParsePagination(t *testing.T) {
+	tests := []struct {
+		name           string
+		query          string
+		maxLimit       int
+		expectedLimit  int
+		expectedOffset int
+	}{
+		{
+			name:           "Defaults - no query params",
+			query:          "/",
+			maxLimit:       200,
+			expectedLimit:  50,
+			expectedOffset: 0,
+		},
+		{
+			name:           "Custom values",
+			query:          "/?limit=20&offset=10",
+			maxLimit:       200,
+			expectedLimit:  20,
+			expectedOffset: 10,
+		},
+		{
+			name:           "Max limit capped",
+			query:          "/?limit=500",
+			maxLimit:       200,
+			expectedLimit:  200,
+			expectedOffset: 0,
+		},
+		{
+			name:           "Negative offset ignored",
+			query:          "/?offset=-5",
+			maxLimit:       200,
+			expectedLimit:  50,
+			expectedOffset: 0,
+		},
+		{
+			name:           "Invalid limit falls back to default",
+			query:          "/?limit=abc",
+			maxLimit:       200,
+			expectedLimit:  50,
+			expectedOffset: 0,
+		},
+		{
+			name:           "Zero limit falls back to default",
+			query:          "/?limit=0",
+			maxLimit:       200,
+			expectedLimit:  50,
+			expectedOffset: 0,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			e := echo.New()
+			req := httptest.NewRequest(http.MethodGet, tt.query, nil)
+			rec := httptest.NewRecorder()
+			c := e.NewContext(req, rec)
+
+			limit, offset := ParsePagination(c, tt.maxLimit)
+
+			assert.Equal(t, tt.expectedLimit, limit, "limit mismatch")
+			assert.Equal(t, tt.expectedOffset, offset, "offset mismatch")
+		})
+	}
+}

internal/handlers/residence_handler.go

@@ -17,17 +17,19 @@ import (
 
 // ResidenceHandler handles residence-related HTTP requests
 type ResidenceHandler struct {
-	residenceService *services.ResidenceService
-	pdfService       *services.PDFService
-	emailService     *services.EmailService
+	residenceService  *services.ResidenceService
+	pdfService        *services.PDFService
+	emailService      *services.EmailService
+	pdfReportsEnabled bool
 }
 
 // NewResidenceHandler creates a new residence handler
-func NewResidenceHandler(residenceService *services.ResidenceService, pdfService *services.PDFService, emailService *services.EmailService) *ResidenceHandler {
+func NewResidenceHandler(residenceService *services.ResidenceService, pdfService *services.PDFService, emailService *services.EmailService, pdfReportsEnabled bool) *ResidenceHandler {
 	return &ResidenceHandler{
-		residenceService: residenceService,
-		pdfService:       pdfService,
-		emailService:     emailService,
+		residenceService:  residenceService,
+		pdfService:        pdfService,
+		emailService:      emailService,
+		pdfReportsEnabled: pdfReportsEnabled,
 	}
 }
 
@@ -283,6 +285,10 @@ func (h *ResidenceHandler) GetResidenceTypes(c echo.Context) error {
 // GenerateTasksReport handles POST /api/residences/:id/generate-tasks-report/
 // Generates a PDF report of tasks for the residence and emails it
 func (h *ResidenceHandler) GenerateTasksReport(c echo.Context) error {
+	if !h.pdfReportsEnabled {
+		return apperrors.BadRequest("error.feature_disabled")
+	}
+
 	user := c.Get(middleware.AuthUserKey).(*models.User)
 
 	residenceID, err := strconv.ParseUint(c.Param("id"), 10, 32)

internal/handlers/residence_handler_test.go

@@ -25,7 +25,7 @@ func setupResidenceHandler(t *testing.T) (*ResidenceHandler, *echo.Echo, *gorm.D
 	userRepo := repositories.NewUserRepository(db)
 	cfg := &config.Config{}
 	residenceService := services.NewResidenceService(residenceRepo, userRepo, cfg)
-	handler := NewResidenceHandler(residenceService, nil, nil)
+	handler := NewResidenceHandler(residenceService, nil, nil, true)
 	e := testutil.SetupTestRouter()
 	return handler, e, db
 }

internal/handlers/subscription_webhook_handler.go

@@ -26,17 +26,23 @@ import (
 type SubscriptionWebhookHandler struct {
 	subscriptionRepo *repositories.SubscriptionRepository
 	userRepo         *repositories.UserRepository
+	webhookEventRepo *repositories.WebhookEventRepository
 	appleRootCerts   []*x509.Certificate
+	enabled          bool
 }
 
 // NewSubscriptionWebhookHandler creates a new webhook handler
 func NewSubscriptionWebhookHandler(
 	subscriptionRepo *repositories.SubscriptionRepository,
 	userRepo *repositories.UserRepository,
+	webhookEventRepo *repositories.WebhookEventRepository,
+	enabled bool,
 ) *SubscriptionWebhookHandler {
 	return &SubscriptionWebhookHandler{
 		subscriptionRepo: subscriptionRepo,
 		userRepo:         userRepo,
+		webhookEventRepo: webhookEventRepo,
+		enabled:          enabled,
 	}
 }
 
@@ -94,6 +100,11 @@ type AppleRenewalInfo struct {
 
 // HandleAppleWebhook handles POST /api/subscription/webhook/apple/
 func (h *SubscriptionWebhookHandler) HandleAppleWebhook(c echo.Context) error {
+	if !h.enabled {
+		log.Printf("Apple Webhook: webhooks disabled by feature flag")
+		return c.JSON(http.StatusOK, map[string]interface{}{"status": "webhooks_disabled"})
+	}
+
 	body, err := io.ReadAll(c.Request().Body)
 	if err != nil {
 		log.Printf("Apple Webhook: Failed to read body: %v", err)
@@ -116,6 +127,18 @@ func (h *SubscriptionWebhookHandler) HandleAppleWebhook(c echo.Context) error {
 	log.Printf("Apple Webhook: Received %s (subtype: %s) for bundle %s",
 		notification.NotificationType, notification.Subtype, notification.Data.BundleID)
 
+	// Dedup check using notificationUUID
+	if notification.NotificationUUID != "" {
+		alreadyProcessed, err := h.webhookEventRepo.HasProcessed("apple", notification.NotificationUUID)
+		if err != nil {
+			log.Printf("Apple Webhook: Failed to check dedup: %v", err)
+			// Continue processing on dedup check failure (fail-open)
+		} else if alreadyProcessed {
+			log.Printf("Apple Webhook: Duplicate event %s, skipping", notification.NotificationUUID)
+			return c.JSON(http.StatusOK, map[string]interface{}{"status": "duplicate"})
+		}
+	}
+
 	// Verify bundle ID matches our app
 	cfg := config.Get()
 	if cfg != nil && cfg.AppleIAP.BundleID != "" {
@@ -145,6 +168,13 @@ func (h *SubscriptionWebhookHandler) HandleAppleWebhook(c echo.Context) error {
 		// Still return 200 to prevent Apple from retrying
 	}
 
+	// Record processed event for dedup
+	if notification.NotificationUUID != "" {
+		if err := h.webhookEventRepo.RecordEvent("apple", notification.NotificationUUID, notification.NotificationType, ""); err != nil {
+			log.Printf("Apple Webhook: Failed to record event: %v", err)
+		}
+	}
+
 	// Always return 200 OK to acknowledge receipt
 	return c.JSON(http.StatusOK, map[string]interface{}{"status": "received"})
 }
@@ -450,6 +480,11 @@ const (
 
 // HandleGoogleWebhook handles POST /api/subscription/webhook/google/
 func (h *SubscriptionWebhookHandler) HandleGoogleWebhook(c echo.Context) error {
+	if !h.enabled {
+		log.Printf("Google Webhook: webhooks disabled by feature flag")
+		return c.JSON(http.StatusOK, map[string]interface{}{"status": "webhooks_disabled"})
+	}
+
 	body, err := io.ReadAll(c.Request().Body)
 	if err != nil {
 		log.Printf("Google Webhook: Failed to read body: %v", err)
@@ -475,6 +510,19 @@ func (h *SubscriptionWebhookHandler) HandleGoogleWebhook(c echo.Context) error {
 		return c.JSON(http.StatusBadRequest, map[string]interface{}{"error": "invalid developer notification"})
 	}
 
+	// Dedup check using messageId
+	messageID := notification.Message.MessageID
+	if messageID != "" {
+		alreadyProcessed, err := h.webhookEventRepo.HasProcessed("google", messageID)
+		if err != nil {
+			log.Printf("Google Webhook: Failed to check dedup: %v", err)
+			// Continue processing on dedup check failure (fail-open)
+		} else if alreadyProcessed {
+			log.Printf("Google Webhook: Duplicate event %s, skipping", messageID)
+			return c.JSON(http.StatusOK, map[string]interface{}{"status": "duplicate"})
+		}
+	}
+
 	// Handle test notification
 	if devNotification.TestNotification != nil {
 		log.Printf("Google Webhook: Received test notification")
@@ -499,6 +547,17 @@ func (h *SubscriptionWebhookHandler) HandleGoogleWebhook(c echo.Context) error {
 		}
 	}
 
+	// Record processed event for dedup
+	if messageID != "" {
+		eventType := "unknown"
+		if devNotification.SubscriptionNotification != nil {
+			eventType = fmt.Sprintf("subscription_%d", devNotification.SubscriptionNotification.NotificationType)
+		}
+		if err := h.webhookEventRepo.RecordEvent("google", messageID, eventType, ""); err != nil {
+			log.Printf("Google Webhook: Failed to record event: %v", err)
+		}
+	}
+
 	// Acknowledge the message
 	return c.JSON(http.StatusOK, map[string]interface{}{"status": "received"})
 }

internal/handlers/task_handler_test.go

@@ -358,7 +358,7 @@ func TestTaskHandler_UncancelTask(t *testing.T) {
 
 	// Cancel first
 	taskRepo := repositories.NewTaskRepository(db)
-	taskRepo.Cancel(task.ID)
+	taskRepo.Cancel(task.ID, task.Version)
 
 	authGroup := e.Group("/api/tasks")
 	authGroup.Use(testutil.MockAuthMiddleware(user))
@@ -418,7 +418,7 @@ func TestTaskHandler_UnarchiveTask(t *testing.T) {
 
 	// Archive first
 	taskRepo := repositories.NewTaskRepository(db)
-	taskRepo.Archive(task.ID)
+	taskRepo.Archive(task.ID, task.Version)
 
 	authGroup := e.Group("/api/tasks")
 	authGroup.Use(testutil.MockAuthMiddleware(user))

internal/i18n/i18n.go

@@ -16,7 +16,7 @@ var translationFS embed.FS
 var Bundle *i18n.Bundle
 
 // SupportedLanguages lists all supported language codes
-var SupportedLanguages = []string{"en", "es", "fr", "de", "pt"}
+var SupportedLanguages = []string{"en", "es", "fr", "de", "pt", "it", "ja", "ko", "nl", "zh"}
 
 // DefaultLanguage is the fallback language
 const DefaultLanguage = "en"

internal/integration/integration_test.go

@@ -137,7 +137,7 @@ func setupIntegrationTest(t *testing.T) *TestApp {
 
 	// Create handlers
 	authHandler := handlers.NewAuthHandler(authService, nil, nil)
-	residenceHandler := handlers.NewResidenceHandler(residenceService, nil, nil)
+	residenceHandler := handlers.NewResidenceHandler(residenceService, nil, nil, true)
 	taskHandler := handlers.NewTaskHandler(taskService, nil)
 	contractorHandler := handlers.NewContractorHandler(contractorService)
 
@@ -1621,7 +1621,7 @@ func setupContractorTest(t *testing.T) *TestApp {
 
 	// Create handlers
 	authHandler := handlers.NewAuthHandler(authService, nil, nil)
-	residenceHandler := handlers.NewResidenceHandler(residenceService, nil, nil)
+	residenceHandler := handlers.NewResidenceHandler(residenceService, nil, nil, true)
 	taskHandler := handlers.NewTaskHandler(taskService, nil)
 	contractorHandler := handlers.NewContractorHandler(contractorService)
 

internal/integration/subscription_is_free_test.go

@@ -63,7 +63,7 @@ func setupSubscriptionTest(t *testing.T) *SubscriptionTestApp {
 
 	// Create handlers
 	authHandler := handlers.NewAuthHandler(authService, nil, nil)
-	residenceHandler := handlers.NewResidenceHandler(residenceService, nil, nil)
+	residenceHandler := handlers.NewResidenceHandler(residenceService, nil, nil, true)
 	subscriptionHandler := handlers.NewSubscriptionHandler(subscriptionService)
 
 	// Create router

internal/middleware/logger.go

@@ -0,0 +1,53 @@
+package middleware
+
+import (
+	"time"
+
+	"github.com/labstack/echo/v4"
+	"github.com/rs/zerolog/log"
+
+	"github.com/treytartt/casera-api/internal/models"
+)
+
+// StructuredLogger is zerolog-based request logging middleware that includes
+// correlation IDs, user IDs, and latency metrics.
+func StructuredLogger() echo.MiddlewareFunc {
+	return func(next echo.HandlerFunc) echo.HandlerFunc {
+		return func(c echo.Context) error {
+			start := time.Now()
+
+			err := next(c)
+
+			latency := time.Since(start)
+
+			// Build structured log event
+			event := log.Info()
+			if c.Response().Status >= 500 {
+				event = log.Error()
+			} else if c.Response().Status >= 400 {
+				event = log.Warn()
+			}
+
+			// Request ID
+			if reqID := GetRequestID(c); reqID != "" {
+				event = event.Str("request_id", reqID)
+			}
+
+			// User ID (from auth middleware)
+			if user, ok := c.Get(AuthUserKey).(*models.User); ok && user != nil {
+				event = event.Uint("user_id", user.ID)
+			}
+
+			event.
+				Str("method", c.Request().Method).
+				Str("path", c.Path()).
+				Str("uri", c.Request().RequestURI).
+				Int("status", c.Response().Status).
+				Int64("latency_ms", latency.Milliseconds()).
+				Str("remote_ip", c.RealIP()).
+				Msg("request")
+
+			return err
+		}
+	}
+}

internal/middleware/request_id.go

@@ -0,0 +1,43 @@
+package middleware
+
+import (
+	"github.com/google/uuid"
+	"github.com/labstack/echo/v4"
+)
+
+const (
+	// HeaderXRequestID is the header key for request correlation IDs
+	HeaderXRequestID = "X-Request-ID"
+	// ContextKeyRequestID is the echo context key for the request ID
+	ContextKeyRequestID = "request_id"
+)
+
+// RequestIDMiddleware generates a UUID per request, sets it as X-Request-ID header,
+// and stores it in the echo context for downstream use.
+func RequestIDMiddleware() echo.MiddlewareFunc {
+	return func(next echo.HandlerFunc) echo.HandlerFunc {
+		return func(c echo.Context) error {
+			// Use existing request ID from header if present, otherwise generate one
+			reqID := c.Request().Header.Get(HeaderXRequestID)
+			if reqID == "" {
+				reqID = uuid.New().String()
+			}
+
+			// Store in context
+			c.Set(ContextKeyRequestID, reqID)
+
+			// Set response header
+			c.Response().Header().Set(HeaderXRequestID, reqID)
+
+			return next(c)
+		}
+	}
+}
+
+// GetRequestID extracts the request ID from the echo context
+func GetRequestID(c echo.Context) string {
+	if id, ok := c.Get(ContextKeyRequestID).(string); ok {
+		return id
+	}
+	return ""
+}

internal/models/task.go

@@ -85,6 +85,9 @@ type Task struct {
 	IsCancelled   bool             `gorm:"column:is_cancelled;default:false;index" json:"is_cancelled"`
 	IsArchived    bool             `gorm:"column:is_archived;default:false;index" json:"is_archived"`
 
+	// Optimistic locking version
+	Version       int              `gorm:"column:version;not null;default:1" json:"-"`
+
 	// Parent task for recurring tasks
 	ParentTaskID  *uint            `gorm:"column:parent_task_id;index" json:"parent_task_id"`
 	ParentTask    *Task            `gorm:"foreignKey:ParentTaskID" json:"parent_task,omitempty"`

internal/push/client.go

@@ -16,13 +16,14 @@ const (
 
 // Client provides a unified interface for sending push notifications
 type Client struct {
-	apns *APNsClient
-	fcm  *FCMClient
+	apns    *APNsClient
+	fcm     *FCMClient
+	enabled bool
 }
 
 // NewClient creates a new unified push notification client
-func NewClient(cfg *config.PushConfig) (*Client, error) {
-	client := &Client{}
+func NewClient(cfg *config.PushConfig, enabled bool) (*Client, error) {
+	client := &Client{enabled: enabled}
 
 	// Initialize APNs client (iOS)
 	if cfg.APNSKeyPath != "" && cfg.APNSKeyID != "" && cfg.APNSTeamID != "" {
@@ -55,6 +56,10 @@ func NewClient(cfg *config.PushConfig) (*Client, error) {
 
 // SendToIOS sends a push notification to iOS devices
 func (c *Client) SendToIOS(ctx context.Context, tokens []string, title, message string, data map[string]string) error {
+	if !c.enabled {
+		log.Debug().Msg("Push notifications disabled by feature flag")
+		return nil
+	}
 	if c.apns == nil {
 		log.Warn().Msg("APNs client not initialized, skipping iOS push")
 		return nil
@@ -64,6 +69,10 @@ func (c *Client) SendToIOS(ctx context.Context, tokens []string, title, message
 
 // SendToAndroid sends a push notification to Android devices
 func (c *Client) SendToAndroid(ctx context.Context, tokens []string, title, message string, data map[string]string) error {
+	if !c.enabled {
+		log.Debug().Msg("Push notifications disabled by feature flag")
+		return nil
+	}
 	if c.fcm == nil {
 		log.Warn().Msg("FCM client not initialized, skipping Android push")
 		return nil
@@ -73,6 +82,10 @@ func (c *Client) SendToAndroid(ctx context.Context, tokens []string, title, mess
 
 // SendToAll sends a push notification to both iOS and Android devices
 func (c *Client) SendToAll(ctx context.Context, iosTokens, androidTokens []string, title, message string, data map[string]string) error {
+	if !c.enabled {
+		log.Debug().Msg("Push notifications disabled by feature flag")
+		return nil
+	}
 	var lastErr error
 
 	if len(iosTokens) > 0 {
@@ -105,6 +118,10 @@ func (c *Client) IsAndroidEnabled() bool {
 // SendActionableNotification sends notifications with action button support
 // iOS receives a category for actionable notifications, Android handles actions via data payload
 func (c *Client) SendActionableNotification(ctx context.Context, iosTokens, androidTokens []string, title, message string, data map[string]string, iosCategoryID string) error {
+	if !c.enabled {
+		log.Debug().Msg("Push notifications disabled by feature flag")
+		return nil
+	}
 	var lastErr error
 
 	if len(iosTokens) > 0 {

internal/repositories/subscription_repo.go

@@ -57,12 +57,19 @@ func (r *SubscriptionRepository) Update(sub *models.UserSubscription) error {
 	return r.db.Save(sub).Error
 }
 
-// UpgradeToPro upgrades a user to Pro tier
+// UpgradeToPro upgrades a user to Pro tier using a transaction with row locking
+// to prevent concurrent subscription mutations from corrupting state.
 func (r *SubscriptionRepository) UpgradeToPro(userID uint, expiresAt time.Time, platform string) error {
-	now := time.Now().UTC()
-	return r.db.Model(&models.UserSubscription{}).
-		Where("user_id = ?", userID).
-		Updates(map[string]interface{}{
+	return r.db.Transaction(func(tx *gorm.DB) error {
+		// Lock the row for update
+		var sub models.UserSubscription
+		if err := tx.Set("gorm:query_option", "FOR UPDATE").
+			Where("user_id = ?", userID).First(&sub).Error; err != nil {
+			return err
+		}
+
+		now := time.Now().UTC()
+		return tx.Model(&sub).Updates(map[string]interface{}{
 			"tier":          models.TierPro,
 			"subscribed_at": now,
 			"expires_at":    expiresAt,
@@ -70,18 +77,27 @@ func (r *SubscriptionRepository) UpgradeToPro(userID uint, expiresAt time.Time,
 			"platform":      platform,
 			"auto_renew":    true,
 		}).Error
+	})
 }
 
-// DowngradeToFree downgrades a user to Free tier
+// DowngradeToFree downgrades a user to Free tier using a transaction with row locking
+// to prevent concurrent subscription mutations from corrupting state.
 func (r *SubscriptionRepository) DowngradeToFree(userID uint) error {
-	now := time.Now().UTC()
-	return r.db.Model(&models.UserSubscription{}).
-		Where("user_id = ?", userID).
-		Updates(map[string]interface{}{
+	return r.db.Transaction(func(tx *gorm.DB) error {
+		// Lock the row for update
+		var sub models.UserSubscription
+		if err := tx.Set("gorm:query_option", "FOR UPDATE").
+			Where("user_id = ?", userID).First(&sub).Error; err != nil {
+			return err
+		}
+
+		now := time.Now().UTC()
+		return tx.Model(&sub).Updates(map[string]interface{}{
 			"tier":         models.TierFree,
 			"cancelled_at": now,
 			"auto_renew":   false,
 		}).Error
+	})
 }
 
 // SetAutoRenew sets the auto-renew flag

internal/repositories/task_repo.go

@@ -1,6 +1,7 @@
 package repositories
 
 import (
+	"errors"
 	"fmt"
 	"time"
 
@@ -11,6 +12,9 @@ import (
 	"github.com/treytartt/casera-api/internal/task/categorization"
 )
 
+// ErrVersionConflict indicates a concurrent modification was detected
+var ErrVersionConflict = errors.New("version conflict: task was modified by another request")
+
 // TaskRepository handles database operations for tasks
 type TaskRepository struct {
 	db *gorm.DB
@@ -294,10 +298,39 @@ func (r *TaskRepository) Create(task *models.Task) error {
 	return r.db.Create(task).Error
 }
 
-// Update updates a task
-// Uses Omit to exclude associations that shouldn't be updated via Save
+// Update updates a task with optimistic locking.
+// The update only succeeds if the task's version in the database matches the expected version.
+// On success, the local task.Version is incremented to reflect the new version.
 func (r *TaskRepository) Update(task *models.Task) error {
-	return r.db.Omit("Residence", "CreatedBy", "AssignedTo", "Category", "Priority", "Frequency", "ParentTask", "Completions").Save(task).Error
+	result := r.db.Model(task).
+		Where("id = ? AND version = ?", task.ID, task.Version).
+		Omit("Residence", "CreatedBy", "AssignedTo", "Category", "Priority", "Frequency", "ParentTask", "Completions").
+		Updates(map[string]interface{}{
+			"title":                task.Title,
+			"description":          task.Description,
+			"category_id":          task.CategoryID,
+			"priority_id":          task.PriorityID,
+			"frequency_id":         task.FrequencyID,
+			"custom_interval_days": task.CustomIntervalDays,
+			"in_progress":          task.InProgress,
+			"assigned_to_id":       task.AssignedToID,
+			"due_date":             task.DueDate,
+			"next_due_date":        task.NextDueDate,
+			"estimated_cost":       task.EstimatedCost,
+			"actual_cost":          task.ActualCost,
+			"contractor_id":        task.ContractorID,
+			"is_cancelled":         task.IsCancelled,
+			"is_archived":          task.IsArchived,
+			"version":              gorm.Expr("version + 1"),
+		})
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return ErrVersionConflict
+	}
+	task.Version++ // Update local copy
+	return nil
 }
 
 // Delete hard-deletes a task
@@ -307,39 +340,89 @@ func (r *TaskRepository) Delete(id uint) error {
 
 // === Task State Operations ===
 
-// MarkInProgress marks a task as in progress
-func (r *TaskRepository) MarkInProgress(id uint) error {
-	return r.db.Model(&models.Task{}).
-		Where("id = ?", id).
-		Update("in_progress", true).Error
+// MarkInProgress marks a task as in progress with optimistic locking.
+func (r *TaskRepository) MarkInProgress(id uint, version int) error {
+	result := r.db.Model(&models.Task{}).
+		Where("id = ? AND version = ?", id, version).
+		Updates(map[string]interface{}{
+			"in_progress": true,
+			"version":     gorm.Expr("version + 1"),
+		})
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return ErrVersionConflict
+	}
+	return nil
 }
 
-// Cancel cancels a task
-func (r *TaskRepository) Cancel(id uint) error {
-	return r.db.Model(&models.Task{}).
-		Where("id = ?", id).
-		Update("is_cancelled", true).Error
+// Cancel cancels a task with optimistic locking.
+func (r *TaskRepository) Cancel(id uint, version int) error {
+	result := r.db.Model(&models.Task{}).
+		Where("id = ? AND version = ?", id, version).
+		Updates(map[string]interface{}{
+			"is_cancelled": true,
+			"version":      gorm.Expr("version + 1"),
+		})
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return ErrVersionConflict
+	}
+	return nil
 }
 
-// Uncancel uncancels a task
-func (r *TaskRepository) Uncancel(id uint) error {
-	return r.db.Model(&models.Task{}).
-		Where("id = ?", id).
-		Update("is_cancelled", false).Error
+// Uncancel uncancels a task with optimistic locking.
+func (r *TaskRepository) Uncancel(id uint, version int) error {
+	result := r.db.Model(&models.Task{}).
+		Where("id = ? AND version = ?", id, version).
+		Updates(map[string]interface{}{
+			"is_cancelled": false,
+			"version":      gorm.Expr("version + 1"),
+		})
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return ErrVersionConflict
+	}
+	return nil
 }
 
-// Archive archives a task
-func (r *TaskRepository) Archive(id uint) error {
-	return r.db.Model(&models.Task{}).
-		Where("id = ?", id).
-		Update("is_archived", true).Error
+// Archive archives a task with optimistic locking.
+func (r *TaskRepository) Archive(id uint, version int) error {
+	result := r.db.Model(&models.Task{}).
+		Where("id = ? AND version = ?", id, version).
+		Updates(map[string]interface{}{
+			"is_archived": true,
+			"version":     gorm.Expr("version + 1"),
+		})
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return ErrVersionConflict
+	}
+	return nil
 }
 
-// Unarchive unarchives a task
-func (r *TaskRepository) Unarchive(id uint) error {
-	return r.db.Model(&models.Task{}).
-		Where("id = ?", id).
-		Update("is_archived", false).Error
+// Unarchive unarchives a task with optimistic locking.
+func (r *TaskRepository) Unarchive(id uint, version int) error {
+	result := r.db.Model(&models.Task{}).
+		Where("id = ? AND version = ?", id, version).
+		Updates(map[string]interface{}{
+			"is_archived": false,
+			"version":     gorm.Expr("version + 1"),
+		})
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return ErrVersionConflict
+	}
+	return nil
 }
 
 // === Kanban Board ===

internal/repositories/task_repo_test.go

@@ -113,7 +113,7 @@ func TestTaskRepository_Cancel(t *testing.T) {
 
 	assert.False(t, task.IsCancelled)
 
-	err := repo.Cancel(task.ID)
+	err := repo.Cancel(task.ID, task.Version)
 	require.NoError(t, err)
 
 	found, err := repo.FindByID(task.ID)
@@ -129,8 +129,8 @@ func TestTaskRepository_Uncancel(t *testing.T) {
 	residence := testutil.CreateTestResidence(t, db, user.ID, "Test House")
 	task := testutil.CreateTestTask(t, db, residence.ID, user.ID, "Test Task")
 
-	repo.Cancel(task.ID)
-	err := repo.Uncancel(task.ID)
+	repo.Cancel(task.ID, task.Version)
+	err := repo.Uncancel(task.ID, task.Version+1) // version incremented by Cancel
 	require.NoError(t, err)
 
 	found, err := repo.FindByID(task.ID)
@@ -146,7 +146,7 @@ func TestTaskRepository_Archive(t *testing.T) {
 	residence := testutil.CreateTestResidence(t, db, user.ID, "Test House")
 	task := testutil.CreateTestTask(t, db, residence.ID, user.ID, "Test Task")
 
-	err := repo.Archive(task.ID)
+	err := repo.Archive(task.ID, task.Version)
 	require.NoError(t, err)
 
 	found, err := repo.FindByID(task.ID)
@@ -162,8 +162,8 @@ func TestTaskRepository_Unarchive(t *testing.T) {
 	residence := testutil.CreateTestResidence(t, db, user.ID, "Test House")
 	task := testutil.CreateTestTask(t, db, residence.ID, user.ID, "Test Task")
 
-	repo.Archive(task.ID)
-	err := repo.Unarchive(task.ID)
+	repo.Archive(task.ID, task.Version)
+	err := repo.Unarchive(task.ID, task.Version+1) // version incremented by Archive
 	require.NoError(t, err)
 
 	found, err := repo.FindByID(task.ID)
@@ -316,7 +316,7 @@ func TestKanbanBoard_CancelledTasksHiddenFromKanbanBoard(t *testing.T) {
 
 	// Create a cancelled task
 	task := testutil.CreateTestTask(t, db, residence.ID, user.ID, "Cancelled Task")
-	repo.Cancel(task.ID)
+	repo.Cancel(task.ID, task.Version)
 
 	board, err := repo.GetKanbanData(residence.ID, 30, time.Now().UTC())
 	require.NoError(t, err)
@@ -571,7 +571,7 @@ func TestKanbanBoard_ArchivedTasksHiddenFromKanbanBoard(t *testing.T) {
 	// Create a regular task and an archived task
 	testutil.CreateTestTask(t, db, residence.ID, user.ID, "Regular Task")
 	archivedTask := testutil.CreateTestTask(t, db, residence.ID, user.ID, "Archived Task")
-	repo.Archive(archivedTask.ID)
+	repo.Archive(archivedTask.ID, archivedTask.Version)
 
 	board, err := repo.GetKanbanData(residence.ID, 30, time.Now().UTC())
 	require.NoError(t, err)
@@ -856,7 +856,7 @@ func TestKanbanBoard_MultipleResidences(t *testing.T) {
 
 	// Create a cancelled task in house 1
 	cancelledTask := testutil.CreateTestTask(t, db, residence1.ID, user.ID, "Cancelled in House 1")
-	repo.Cancel(cancelledTask.ID)
+	repo.Cancel(cancelledTask.ID, cancelledTask.Version)
 
 	board, err := repo.GetKanbanDataForMultipleResidences([]uint{residence1.ID, residence2.ID}, 30, time.Now().UTC())
 	require.NoError(t, err)

internal/repositories/webhook_event_repo.go

@@ -0,0 +1,54 @@
+package repositories
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// WebhookEvent represents a processed webhook event for deduplication
+type WebhookEvent struct {
+	ID          uint      `gorm:"primaryKey"`
+	EventID     string    `gorm:"column:event_id;size:255;not null;uniqueIndex:idx_provider_event_id"`
+	Provider    string    `gorm:"column:provider;size:20;not null;uniqueIndex:idx_provider_event_id"`
+	EventType   string    `gorm:"column:event_type;size:100;not null"`
+	ProcessedAt time.Time `gorm:"column:processed_at;autoCreateTime"`
+	PayloadHash string    `gorm:"column:payload_hash;size:64"`
+}
+
+func (WebhookEvent) TableName() string {
+	return "webhook_event_log"
+}
+
+// WebhookEventRepository handles webhook event deduplication
+type WebhookEventRepository struct {
+	db *gorm.DB
+}
+
+// NewWebhookEventRepository creates a new webhook event repository
+func NewWebhookEventRepository(db *gorm.DB) *WebhookEventRepository {
+	return &WebhookEventRepository{db: db}
+}
+
+// HasProcessed checks if an event has already been processed
+func (r *WebhookEventRepository) HasProcessed(provider, eventID string) (bool, error) {
+	var count int64
+	err := r.db.Model(&WebhookEvent{}).
+		Where("provider = ? AND event_id = ?", provider, eventID).
+		Count(&count).Error
+	if err != nil {
+		return false, err
+	}
+	return count > 0, nil
+}
+
+// RecordEvent records a processed webhook event
+func (r *WebhookEventRepository) RecordEvent(provider, eventID, eventType, payloadHash string) error {
+	event := &WebhookEvent{
+		EventID:     eventID,
+		Provider:    provider,
+		EventType:   eventType,
+		PayloadHash: payloadHash,
+	}
+	return r.db.Create(event).Error
+}

internal/repositories/webhook_event_repo_test.go

@@ -0,0 +1,104 @@
+package repositories
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+// setupWebhookTestDB creates an in-memory SQLite database with the
+// WebhookEvent table auto-migrated. This is separate from testutil.SetupTestDB
+// because WebhookEvent lives in the repositories package (not models/) and
+// only needs its own table for testing.
+func setupWebhookTestDB(t *testing.T) *gorm.DB {
+	t.Helper()
+	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Silent),
+	})
+	require.NoError(t, err)
+
+	err = db.AutoMigrate(&WebhookEvent{})
+	require.NoError(t, err)
+
+	return db
+}
+
+func TestWebhookEventRepo_RecordAndCheck(t *testing.T) {
+	db := setupWebhookTestDB(t)
+	repo := NewWebhookEventRepository(db)
+
+	// Record an event
+	err := repo.RecordEvent("apple", "evt_001", "INITIAL_BUY", "abc123hash")
+	require.NoError(t, err)
+
+	// HasProcessed should return true for the same provider + event ID
+	processed, err := repo.HasProcessed("apple", "evt_001")
+	require.NoError(t, err)
+	assert.True(t, processed, "expected HasProcessed to return true for a recorded event")
+
+	// HasProcessed should return false for a different event ID
+	processed, err = repo.HasProcessed("apple", "evt_999")
+	require.NoError(t, err)
+	assert.False(t, processed, "expected HasProcessed to return false for an unrecorded event ID")
+
+	// HasProcessed should return false for a different provider
+	processed, err = repo.HasProcessed("google", "evt_001")
+	require.NoError(t, err)
+	assert.False(t, processed, "expected HasProcessed to return false for a different provider")
+}
+
+func TestWebhookEventRepo_DuplicateInsert(t *testing.T) {
+	db := setupWebhookTestDB(t)
+	repo := NewWebhookEventRepository(db)
+
+	// First insert should succeed
+	err := repo.RecordEvent("apple", "evt_dup", "RENEWAL", "hash1")
+	require.NoError(t, err)
+
+	// Second insert with the same provider + event ID should fail (unique constraint)
+	err = repo.RecordEvent("apple", "evt_dup", "RENEWAL", "hash1")
+	require.Error(t, err, "expected an error when inserting a duplicate provider + event_id")
+
+	// Verify only one row exists
+	var count int64
+	db.Model(&WebhookEvent{}).Where("provider = ? AND event_id = ?", "apple", "evt_dup").Count(&count)
+	assert.Equal(t, int64(1), count, "expected exactly one row for the duplicated event")
+}
+
+func TestWebhookEventRepo_DifferentProviders(t *testing.T) {
+	db := setupWebhookTestDB(t)
+	repo := NewWebhookEventRepository(db)
+
+	sharedEventID := "evt_shared_123"
+
+	// Record event for "apple" provider
+	err := repo.RecordEvent("apple", sharedEventID, "INITIAL_BUY", "applehash")
+	require.NoError(t, err)
+
+	// HasProcessed should return true for "apple"
+	processed, err := repo.HasProcessed("apple", sharedEventID)
+	require.NoError(t, err)
+	assert.True(t, processed, "expected HasProcessed to return true for apple provider")
+
+	// HasProcessed should return false for "google" with the same event ID
+	processed, err = repo.HasProcessed("google", sharedEventID)
+	require.NoError(t, err)
+	assert.False(t, processed, "expected HasProcessed to return false for google provider with the same event ID")
+
+	// Recording the same event ID under "google" should succeed (different provider)
+	err = repo.RecordEvent("google", sharedEventID, "INITIAL_BUY", "googlehash")
+	require.NoError(t, err)
+
+	// Now both providers should show as processed
+	processed, err = repo.HasProcessed("apple", sharedEventID)
+	require.NoError(t, err)
+	assert.True(t, processed, "expected apple to still be processed")
+
+	processed, err = repo.HasProcessed("google", sharedEventID)
+	require.NoError(t, err)
+	assert.True(t, processed, "expected google to now be processed")
+}

internal/router/router.go

@@ -54,8 +54,13 @@ func SetupRouter(deps *Dependencies) *echo.Echo {
 	// which don't use trailing slashes. Mobile API routes explicitly include trailing slashes.
 
 	// Global middleware
+	e.Use(custommiddleware.RequestIDMiddleware())
 	e.Use(utils.EchoRecovery())
-	e.Use(utils.EchoLogger())
+	e.Use(custommiddleware.StructuredLogger())
+	e.Use(middleware.BodyLimit("1M")) // 1MB default for JSON payloads
+	e.Use(middleware.TimeoutWithConfig(middleware.TimeoutConfig{
+		Timeout: 30 * time.Second,
+	}))
 	e.Use(corsMiddleware(cfg))
 	e.Use(i18n.Middleware())
 
@@ -126,8 +131,11 @@ func SetupRouter(deps *Dependencies) *echo.Echo {
 	subscriptionService := services.NewSubscriptionService(subscriptionRepo, residenceRepo, taskRepo, contractorRepo, documentRepo)
 	taskTemplateService := services.NewTaskTemplateService(taskTemplateRepo)
 
+	// Initialize webhook event repo for deduplication
+	webhookEventRepo := repositories.NewWebhookEventRepository(deps.DB)
+
 	// Initialize webhook handler for Apple/Google subscription notifications
-	subscriptionWebhookHandler := handlers.NewSubscriptionWebhookHandler(subscriptionRepo, userRepo)
+	subscriptionWebhookHandler := handlers.NewSubscriptionWebhookHandler(subscriptionRepo, userRepo, webhookEventRepo, cfg.Features.WebhooksEnabled)
 
 	// Initialize middleware
 	authMiddleware := custommiddleware.NewAuthMiddleware(deps.DB, deps.Cache)
@@ -141,7 +149,7 @@ func SetupRouter(deps *Dependencies) *echo.Echo {
 	authHandler.SetAppleAuthService(appleAuthService)
 	authHandler.SetGoogleAuthService(googleAuthService)
 	userHandler := handlers.NewUserHandler(userService)
-	residenceHandler := handlers.NewResidenceHandler(residenceService, deps.PDFService, deps.EmailService)
+	residenceHandler := handlers.NewResidenceHandler(residenceService, deps.PDFService, deps.EmailService, cfg.Features.PDFReportsEnabled)
 	taskHandler := handlers.NewTaskHandler(taskService, deps.StorageService)
 	contractorHandler := handlers.NewContractorHandler(contractorService)
 	documentHandler := handlers.NewDocumentHandler(documentService, deps.StorageService)

internal/services/email_service.go

@@ -15,22 +15,28 @@ import (
 
 // EmailService handles sending emails
 type EmailService struct {
-	cfg    *config.EmailConfig
-	dialer *gomail.Dialer
+	cfg     *config.EmailConfig
+	dialer  *gomail.Dialer
+	enabled bool
 }
 
 // NewEmailService creates a new email service
-func NewEmailService(cfg *config.EmailConfig) *EmailService {
+func NewEmailService(cfg *config.EmailConfig, enabled bool) *EmailService {
 	dialer := gomail.NewDialer(cfg.Host, cfg.Port, cfg.User, cfg.Password)
 
 	return &EmailService{
-		cfg:    cfg,
-		dialer: dialer,
+		cfg:     cfg,
+		dialer:  dialer,
+		enabled: enabled,
 	}
 }
 
 // SendEmail sends an email
 func (s *EmailService) SendEmail(to, subject, htmlBody, textBody string) error {
+	if !s.enabled {
+		log.Debug().Msg("Email sending disabled by feature flag")
+		return nil
+	}
 	m := gomail.NewMessage()
 	m.SetHeader("From", s.cfg.From)
 	m.SetHeader("To", to)
@@ -64,6 +70,10 @@ type EmbeddedImage struct {
 
 // SendEmailWithAttachment sends an email with an attachment
 func (s *EmailService) SendEmailWithAttachment(to, subject, htmlBody, textBody string, attachment *EmailAttachment) error {
+	if !s.enabled {
+		log.Debug().Msg("Email sending disabled by feature flag")
+		return nil
+	}
 	m := gomail.NewMessage()
 	m.SetHeader("From", s.cfg.From)
 	m.SetHeader("To", to)
@@ -94,6 +104,10 @@ func (s *EmailService) SendEmailWithAttachment(to, subject, htmlBody, textBody s
 
 // SendEmailWithEmbeddedImages sends an email with inline embedded images
 func (s *EmailService) SendEmailWithEmbeddedImages(to, subject, htmlBody, textBody string, images []EmbeddedImage) error {
+	if !s.enabled {
+		log.Debug().Msg("Email sending disabled by feature flag")
+		return nil
+	}
 	m := gomail.NewMessage()
 	m.SetHeader("From", s.cfg.From)
 	m.SetHeader("To", to)

internal/services/task_service.go

@@ -271,6 +271,9 @@ func (s *TaskService) UpdateTask(taskID, userID uint, req *requests.UpdateTaskRe
 	}
 
 	if err := s.taskRepo.Update(task); err != nil {
+		if errors.Is(err, repositories.ErrVersionConflict) {
+			return nil, apperrors.Conflict("error.version_conflict")
+		}
 		return nil, apperrors.Internal(err)
 	}
 
@@ -337,7 +340,10 @@ func (s *TaskService) MarkInProgress(taskID, userID uint, now time.Time) (*respo
 		return nil, apperrors.Forbidden("error.task_access_denied")
 	}
 
-	if err := s.taskRepo.MarkInProgress(taskID); err != nil {
+	if err := s.taskRepo.MarkInProgress(taskID, task.Version); err != nil {
+		if errors.Is(err, repositories.ErrVersionConflict) {
+			return nil, apperrors.Conflict("error.version_conflict")
+		}
 		return nil, apperrors.Internal(err)
 	}
 
@@ -377,7 +383,10 @@ func (s *TaskService) CancelTask(taskID, userID uint, now time.Time) (*responses
 		return nil, apperrors.BadRequest("error.task_already_cancelled")
 	}
 
-	if err := s.taskRepo.Cancel(taskID); err != nil {
+	if err := s.taskRepo.Cancel(taskID, task.Version); err != nil {
+		if errors.Is(err, repositories.ErrVersionConflict) {
+			return nil, apperrors.Conflict("error.version_conflict")
+		}
 		return nil, apperrors.Internal(err)
 	}
 
@@ -413,7 +422,10 @@ func (s *TaskService) UncancelTask(taskID, userID uint, now time.Time) (*respons
 		return nil, apperrors.Forbidden("error.task_access_denied")
 	}
 
-	if err := s.taskRepo.Uncancel(taskID); err != nil {
+	if err := s.taskRepo.Uncancel(taskID, task.Version); err != nil {
+		if errors.Is(err, repositories.ErrVersionConflict) {
+			return nil, apperrors.Conflict("error.version_conflict")
+		}
 		return nil, apperrors.Internal(err)
 	}
 
@@ -453,7 +465,10 @@ func (s *TaskService) ArchiveTask(taskID, userID uint, now time.Time) (*response
 		return nil, apperrors.BadRequest("error.task_already_archived")
 	}
 
-	if err := s.taskRepo.Archive(taskID); err != nil {
+	if err := s.taskRepo.Archive(taskID, task.Version); err != nil {
+		if errors.Is(err, repositories.ErrVersionConflict) {
+			return nil, apperrors.Conflict("error.version_conflict")
+		}
 		return nil, apperrors.Internal(err)
 	}
 
@@ -489,7 +504,10 @@ func (s *TaskService) UnarchiveTask(taskID, userID uint, now time.Time) (*respon
 		return nil, apperrors.Forbidden("error.task_access_denied")
 	}
 
-	if err := s.taskRepo.Unarchive(taskID); err != nil {
+	if err := s.taskRepo.Unarchive(taskID, task.Version); err != nil {
+		if errors.Is(err, repositories.ErrVersionConflict) {
+			return nil, apperrors.Conflict("error.version_conflict")
+		}
 		return nil, apperrors.Internal(err)
 	}
 
@@ -581,6 +599,9 @@ func (s *TaskService) CreateCompletion(req *requests.CreateTaskCompletionRequest
 		task.InProgress = false
 	}
 	if err := s.taskRepo.Update(task); err != nil {
+		if errors.Is(err, repositories.ErrVersionConflict) {
+			return nil, apperrors.Conflict("error.version_conflict")
+		}
 		log.Error().Err(err).Uint("task_id", task.ID).Msg("Failed to update task after completion")
 	}
 
@@ -702,6 +723,9 @@ func (s *TaskService) QuickComplete(taskID uint, userID uint) error {
 		task.InProgress = false
 	}
 	if err := s.taskRepo.Update(task); err != nil {
+		if errors.Is(err, repositories.ErrVersionConflict) {
+			return apperrors.Conflict("error.version_conflict")
+		}
 		log.Error().Err(err).Uint("task_id", task.ID).Msg("Failed to update task after quick completion")
 		return apperrors.Internal(err) // Return error so caller knows the update failed
 	}

internal/task/categorization/chain_breakit_test.go

@@ -0,0 +1,241 @@
+package categorization_test
+
+import (
+	"math/rand"
+	"testing"
+	"time"
+
+	"github.com/treytartt/casera-api/internal/models"
+	"github.com/treytartt/casera-api/internal/task/categorization"
+)
+
+// validColumns is the complete set of KanbanColumn values the chain may return.
+var validColumns = map[categorization.KanbanColumn]bool{
+	categorization.ColumnOverdue:    true,
+	categorization.ColumnDueSoon:    true,
+	categorization.ColumnUpcoming:   true,
+	categorization.ColumnInProgress: true,
+	categorization.ColumnCompleted:  true,
+	categorization.ColumnCancelled:  true,
+}
+
+// FuzzCategorizeTask feeds random task states into CategorizeTask and asserts
+// that the result is always a non-empty, valid KanbanColumn constant.
+func FuzzCategorizeTask(f *testing.F) {
+	f.Add(false, false, false, false, false, 0, false, 0)
+	f.Add(true, false, false, false, false, 0, false, 0)
+	f.Add(false, true, false, false, false, 0, false, 0)
+	f.Add(false, false, true, false, false, 0, false, 0)
+	f.Add(false, false, false, true, false, 0, false, 0)
+	f.Add(false, false, false, false, true, -5, false, 0)
+	f.Add(false, false, false, false, false, 0, true, -5)
+	f.Add(false, false, false, false, false, 0, true, 5)
+	f.Add(false, false, false, false, false, 0, true, 60)
+	f.Add(true, true, true, true, true, -10, true, -10)
+	f.Add(false, false, false, false, true, 100, true, 100)
+
+	f.Fuzz(func(t *testing.T,
+		isCancelled, isArchived, inProgress, hasCompletions bool,
+		hasDueDate bool, dueDateOffsetDays int,
+		hasNextDueDate bool, nextDueDateOffsetDays int,
+	) {
+		now := time.Date(2025, 12, 15, 0, 0, 0, 0, time.UTC)
+
+		task := &models.Task{
+			IsCancelled: isCancelled,
+			IsArchived:  isArchived,
+			InProgress:  inProgress,
+		}
+
+		if hasDueDate {
+			d := now.AddDate(0, 0, dueDateOffsetDays)
+			task.DueDate = &d
+		}
+		if hasNextDueDate {
+			d := now.AddDate(0, 0, nextDueDateOffsetDays)
+			task.NextDueDate = &d
+		}
+		if hasCompletions {
+			task.Completions = []models.TaskCompletion{
+				{BaseModel: models.BaseModel{ID: 1}},
+			}
+		} else {
+			task.Completions = []models.TaskCompletion{}
+		}
+
+		result := categorization.CategorizeTask(task, 30)
+
+		if result == "" {
+			t.Fatalf("CategorizeTask returned empty string for task %+v", task)
+		}
+		if !validColumns[result] {
+			t.Fatalf("CategorizeTask returned invalid column %q for task %+v", result, task)
+		}
+	})
+}
+
+// === Property Tests (1000 random tasks) ===
+
+// TestCategorizeTask_PropertyEveryTaskMapsToExactlyOneColumn uses random tasks
+// to validate the property that every task maps to exactly one column.
+func TestCategorizeTask_PropertyEveryTaskMapsToExactlyOneColumn(t *testing.T) {
+	rng := rand.New(rand.NewSource(42)) // Deterministic seed for reproducibility
+	now := time.Date(2025, 6, 15, 0, 0, 0, 0, time.UTC)
+
+	for i := 0; i < 1000; i++ {
+		task := randomTask(rng, now)
+		column := categorization.CategorizeTask(task, 30)
+
+		if !validColumns[column] {
+			t.Fatalf("Task %d mapped to invalid column %q: %+v", i, column, task)
+		}
+	}
+}
+
+// TestCategorizeTask_CancelledAlwaysWins validates that cancelled takes priority
+// over all other states regardless of other flags using randomized tasks.
+func TestCategorizeTask_CancelledAlwaysWins(t *testing.T) {
+	rng := rand.New(rand.NewSource(42))
+	now := time.Date(2025, 6, 15, 0, 0, 0, 0, time.UTC)
+
+	for i := 0; i < 500; i++ {
+		task := randomTask(rng, now)
+		task.IsCancelled = true
+
+		column := categorization.CategorizeTask(task, 30)
+		if column != categorization.ColumnCancelled {
+			t.Fatalf("Cancelled task %d mapped to %q instead of cancelled_tasks: %+v", i, column, task)
+		}
+	}
+}
+
+// === Timezone / DST Boundary Tests ===
+
+// TestCategorizeTask_UTCMidnightBoundary tests task categorization at exactly
+// UTC midnight, which is the boundary between days.
+func TestCategorizeTask_UTCMidnightBoundary(t *testing.T) {
+	midnight := time.Date(2025, 3, 9, 0, 0, 0, 0, time.UTC)
+	dueDate := midnight
+
+	task := &models.Task{
+		DueDate: &dueDate,
+	}
+
+	// At midnight of the due date, task is NOT overdue (due today)
+	column := categorization.CategorizeTaskWithTime(task, 30, midnight)
+	if column == categorization.ColumnOverdue {
+		t.Errorf("Task due today should not be overdue at midnight, got %q", column)
+	}
+
+	// One day later, task IS overdue
+	nextDay := midnight.AddDate(0, 0, 1)
+	column = categorization.CategorizeTaskWithTime(task, 30, nextDay)
+	if column != categorization.ColumnOverdue {
+		t.Errorf("Task due yesterday should be overdue, got %q", column)
+	}
+}
+
+// TestCategorizeTask_DSTSpringForward tests categorization across DST spring-forward.
+// In US Eastern time, 2:00 AM jumps to 3:00 AM on the second Sunday of March.
+func TestCategorizeTask_DSTSpringForward(t *testing.T) {
+	loc, err := time.LoadLocation("America/New_York")
+	if err != nil {
+		t.Skip("America/New_York timezone not available")
+	}
+
+	// March 9, 2025 is DST spring-forward in Eastern Time
+	dueDate := time.Date(2025, 3, 9, 0, 0, 0, 0, time.UTC) // Stored as UTC
+	task := &models.Task{DueDate: &dueDate}
+
+	// Check at start of March 9 in Eastern time
+	nowET := time.Date(2025, 3, 9, 0, 0, 0, 0, loc)
+	column := categorization.CategorizeTaskWithTime(task, 30, nowET)
+	if column == categorization.ColumnOverdue {
+		t.Errorf("Task due March 9 should not be overdue on March 9 (DST spring-forward), got %q", column)
+	}
+
+	// Check at March 10 - should be overdue now
+	nextDayET := time.Date(2025, 3, 10, 0, 0, 0, 0, loc)
+	column = categorization.CategorizeTaskWithTime(task, 30, nextDayET)
+	if column != categorization.ColumnOverdue {
+		t.Errorf("Task due March 9 should be overdue on March 10, got %q", column)
+	}
+}
+
+// TestCategorizeTask_DSTFallBack tests categorization across DST fall-back.
+// In US Eastern time, 2:00 AM jumps back to 1:00 AM on the first Sunday of November.
+func TestCategorizeTask_DSTFallBack(t *testing.T) {
+	loc, err := time.LoadLocation("America/New_York")
+	if err != nil {
+		t.Skip("America/New_York timezone not available")
+	}
+
+	// November 2, 2025 is DST fall-back in Eastern Time
+	dueDate := time.Date(2025, 11, 2, 0, 0, 0, 0, time.UTC)
+	task := &models.Task{DueDate: &dueDate}
+
+	// On the due date itself - not overdue
+	nowET := time.Date(2025, 11, 2, 0, 0, 0, 0, loc)
+	column := categorization.CategorizeTaskWithTime(task, 30, nowET)
+	if column == categorization.ColumnOverdue {
+		t.Errorf("Task due Nov 2 should not be overdue on Nov 2 (DST fall-back), got %q", column)
+	}
+
+	// Next day - should be overdue
+	nextDayET := time.Date(2025, 11, 3, 0, 0, 0, 0, loc)
+	column = categorization.CategorizeTaskWithTime(task, 30, nextDayET)
+	if column != categorization.ColumnOverdue {
+		t.Errorf("Task due Nov 2 should be overdue on Nov 3, got %q", column)
+	}
+}
+
+// TestIsOverdue_UTCMidnightEdge validates the overdue predicate at exact midnight.
+func TestIsOverdue_UTCMidnightEdge(t *testing.T) {
+	dueDate := time.Date(2025, 12, 31, 0, 0, 0, 0, time.UTC)
+	task := &models.Task{DueDate: &dueDate}
+
+	// On due date: NOT overdue
+	atDueDate := time.Date(2025, 12, 31, 0, 0, 0, 0, time.UTC)
+	column := categorization.CategorizeTaskWithTime(task, 30, atDueDate)
+	if column == categorization.ColumnOverdue {
+		t.Error("Task should not be overdue on its due date")
+	}
+
+	// One second after midnight next day: overdue
+	afterDueDate := time.Date(2026, 1, 1, 0, 0, 1, 0, time.UTC)
+	column = categorization.CategorizeTaskWithTime(task, 30, afterDueDate)
+	if column != categorization.ColumnOverdue {
+		t.Errorf("Task should be overdue after its due date, got %q", column)
+	}
+}
+
+// === Helper ===
+
+func randomTask(rng *rand.Rand, baseTime time.Time) *models.Task {
+	task := &models.Task{
+		IsCancelled: rng.Intn(10) == 0, // 10% chance
+		IsArchived:  rng.Intn(10) == 0, // 10% chance
+		InProgress:  rng.Intn(5) == 0,  // 20% chance
+	}
+
+	if rng.Intn(4) > 0 { // 75% have due date
+		d := baseTime.AddDate(0, 0, rng.Intn(120)-60)
+		task.DueDate = &d
+	}
+
+	if rng.Intn(3) == 0 { // 33% recurring
+		d := baseTime.AddDate(0, 0, rng.Intn(120)-60)
+		task.NextDueDate = &d
+	}
+
+	if rng.Intn(3) == 0 { // 33% have completions
+		count := rng.Intn(3) + 1
+		for i := 0; i < count; i++ {
+			task.Completions = append(task.Completions, models.TaskCompletion{
+				BaseModel: models.BaseModel{ID: uint(i + 1)},
+			})
+		}
+	}
+
+	return task
+}

internal/task/categorization/chain_test.go

@@ -4,10 +4,14 @@ import (
 	"testing"
 	"time"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/treytartt/casera-api/internal/models"
 	"github.com/treytartt/casera-api/internal/task/categorization"
 )
 
+// Ensure assert is used (referenced in fuzz/property tests below)
+var _ = assert.Equal
+
 // Helper to create a time pointer
 func timePtr(t time.Time) *time.Time {
 	return &t
@@ -545,3 +549,255 @@ func TestTimezone_MultipleTasksIntoColumns(t *testing.T) {
 		t.Errorf("Expected task 3 (Jan 15) in due_soon column")
 	}
 }
+
+// ============================================================================
+// FUZZ / PROPERTY TESTS
+// These tests verify invariants that must hold for ALL possible task states,
+// not just specific hand-crafted examples.
+//
+// validColumns is defined in chain_breakit_test.go and shared across test files
+// in the categorization_test package.
+// ============================================================================
+
+// FuzzCategorizeTaskExtended feeds random task states into CategorizeTask using
+// separate boolean flags for date presence and day-offset integers for date
+// values. This complements FuzzCategorizeTask (in chain_breakit_test.go) by
+// exercising the nil-date paths more directly.
+func FuzzCategorizeTaskExtended(f *testing.F) {
+	// Seed corpus: cover a representative spread of boolean/date combinations.
+	//   isCancelled, isArchived, inProgress, hasCompletions,
+	//   hasDueDate, dueDateOffsetDays, hasNextDueDate, nextDueDateOffsetDays
+	f.Add(false, false, false, false, false, 0, false, 0)
+	f.Add(true, false, false, false, false, 0, false, 0)
+	f.Add(false, true, false, false, false, 0, false, 0)
+	f.Add(false, false, true, false, false, 0, false, 0)
+	f.Add(false, false, false, true, false, 0, false, 0)   // completed (no next due, has completions)
+	f.Add(false, false, false, false, true, -5, false, 0)   // overdue via DueDate
+	f.Add(false, false, false, false, false, 0, true, -5)   // overdue via NextDueDate
+	f.Add(false, false, false, false, false, 0, true, 5)    // due soon
+	f.Add(false, false, false, false, false, 0, true, 60)   // upcoming
+	f.Add(true, true, true, true, true, -10, true, -10)     // everything set
+	f.Add(false, false, false, false, true, 100, true, 100) // far future
+
+	f.Fuzz(func(t *testing.T,
+		isCancelled, isArchived, inProgress, hasCompletions bool,
+		hasDueDate bool, dueDateOffsetDays int,
+		hasNextDueDate bool, nextDueDateOffsetDays int,
+	) {
+		now := time.Date(2025, 12, 15, 0, 0, 0, 0, time.UTC)
+
+		task := &models.Task{
+			IsCancelled: isCancelled,
+			IsArchived:  isArchived,
+			InProgress:  inProgress,
+		}
+
+		if hasDueDate {
+			d := now.AddDate(0, 0, dueDateOffsetDays)
+			task.DueDate = &d
+		}
+		if hasNextDueDate {
+			d := now.AddDate(0, 0, nextDueDateOffsetDays)
+			task.NextDueDate = &d
+		}
+		if hasCompletions {
+			task.Completions = []models.TaskCompletion{
+				{BaseModel: models.BaseModel{ID: 1}},
+			}
+		} else {
+			task.Completions = []models.TaskCompletion{}
+		}
+
+		result := categorization.CategorizeTask(task, 30)
+
+		// Invariant 1: result must never be the empty string.
+		if result == "" {
+			t.Fatalf("CategorizeTask returned empty string for task %+v", task)
+		}
+
+		// Invariant 2: result must be one of the valid KanbanColumn constants.
+		if !validColumns[result] {
+			t.Fatalf("CategorizeTask returned invalid column %q for task %+v", result, task)
+		}
+	})
+}
+
+// TestCategorizeTask_MutuallyExclusive exhaustively enumerates all boolean
+// state combinations (IsCancelled, IsArchived, InProgress, hasCompletions)
+// crossed with representative date positions (no date, past, today, within
+// threshold, beyond threshold) and asserts that every task maps to exactly
+// one valid, non-empty column.
+func TestCategorizeTask_MutuallyExclusive(t *testing.T) {
+	now := time.Date(2025, 12, 15, 0, 0, 0, 0, time.UTC)
+	daysThreshold := 30
+
+	// Date scenarios relative to "now" for both DueDate and NextDueDate.
+	type dateScenario struct {
+		name    string
+		dueDate *time.Time
+		nextDue *time.Time
+	}
+
+	past := now.AddDate(0, 0, -5)
+	today := now
+	withinThreshold := now.AddDate(0, 0, 10)
+	beyondThreshold := now.AddDate(0, 0, 60)
+
+	dateScenarios := []dateScenario{
+		{"no dates", nil, nil},
+		{"DueDate past only", &past, nil},
+		{"DueDate today only", &today, nil},
+		{"DueDate within threshold", &withinThreshold, nil},
+		{"DueDate beyond threshold", &beyondThreshold, nil},
+		{"NextDueDate past", nil, &past},
+		{"NextDueDate today", nil, &today},
+		{"NextDueDate within threshold", nil, &withinThreshold},
+		{"NextDueDate beyond threshold", nil, &beyondThreshold},
+		{"both past", &past, &past},
+		{"DueDate past NextDueDate future", &past, &withinThreshold},
+		{"both beyond threshold", &beyondThreshold, &beyondThreshold},
+	}
+
+	boolCombos := []struct {
+		cancelled, archived, inProgress, hasCompletions bool
+	}{
+		{false, false, false, false},
+		{true, false, false, false},
+		{false, true, false, false},
+		{false, false, true, false},
+		{false, false, false, true},
+		{true, true, false, false},
+		{true, false, true, false},
+		{true, false, false, true},
+		{false, true, true, false},
+		{false, true, false, true},
+		{false, false, true, true},
+		{true, true, true, false},
+		{true, true, false, true},
+		{true, false, true, true},
+		{false, true, true, true},
+		{true, true, true, true},
+	}
+
+	for _, ds := range dateScenarios {
+		for _, bc := range boolCombos {
+			task := &models.Task{
+				IsCancelled: bc.cancelled,
+				IsArchived:  bc.archived,
+				InProgress:  bc.inProgress,
+				DueDate:     ds.dueDate,
+				NextDueDate: ds.nextDue,
+			}
+			if bc.hasCompletions {
+				task.Completions = []models.TaskCompletion{
+					{BaseModel: models.BaseModel{ID: 1}},
+				}
+			} else {
+				task.Completions = []models.TaskCompletion{}
+			}
+
+			result := categorization.CategorizeTaskWithTime(task, daysThreshold, now)
+
+			assert.NotEmpty(t, result,
+				"empty column for dates=%s cancelled=%v archived=%v inProgress=%v completions=%v",
+				ds.name, bc.cancelled, bc.archived, bc.inProgress, bc.hasCompletions)
+
+			assert.True(t, validColumns[result],
+				"invalid column %q for dates=%s cancelled=%v archived=%v inProgress=%v completions=%v",
+				result, ds.name, bc.cancelled, bc.archived, bc.inProgress, bc.hasCompletions)
+		}
+	}
+}
+
+// TestCategorizeTask_CancelledAlwaysCancelled verifies the property that any
+// task with IsCancelled=true is always categorized into ColumnCancelled,
+// regardless of all other field values.
+func TestCategorizeTask_CancelledAlwaysCancelled(t *testing.T) {
+	now := time.Date(2025, 12, 15, 0, 0, 0, 0, time.UTC)
+	daysThreshold := 30
+
+	past := now.AddDate(0, 0, -5)
+	future := now.AddDate(0, 0, 10)
+	farFuture := now.AddDate(0, 0, 60)
+
+	dates := []*time.Time{nil, &past, &future, &farFuture}
+	bools := []bool{true, false}
+
+	for _, isArchived := range bools {
+		for _, inProgress := range bools {
+			for _, hasCompletions := range bools {
+				for _, dueDate := range dates {
+					for _, nextDueDate := range dates {
+						task := &models.Task{
+							IsCancelled: true, // always cancelled
+							IsArchived:  isArchived,
+							InProgress:  inProgress,
+							DueDate:     dueDate,
+							NextDueDate: nextDueDate,
+						}
+						if hasCompletions {
+							task.Completions = []models.TaskCompletion{
+								{BaseModel: models.BaseModel{ID: 1}},
+							}
+						} else {
+							task.Completions = []models.TaskCompletion{}
+						}
+
+						result := categorization.CategorizeTaskWithTime(task, daysThreshold, now)
+
+						assert.Equal(t, categorization.ColumnCancelled, result,
+							"cancelled task should always map to ColumnCancelled, got %q "+
+								"(archived=%v inProgress=%v completions=%v dueDate=%v nextDueDate=%v)",
+							result, isArchived, inProgress, hasCompletions, dueDate, nextDueDate)
+					}
+				}
+			}
+		}
+	}
+}
+
+// TestCategorizeTask_ArchivedAlwaysArchived verifies the property that any
+// task with IsArchived=true and IsCancelled=false is always categorized into
+// ColumnCancelled (archived tasks share the cancelled column as both represent
+// "inactive" states), regardless of all other field values.
+func TestCategorizeTask_ArchivedAlwaysArchived(t *testing.T) {
+	now := time.Date(2025, 12, 15, 0, 0, 0, 0, time.UTC)
+	daysThreshold := 30
+
+	past := now.AddDate(0, 0, -5)
+	future := now.AddDate(0, 0, 10)
+	farFuture := now.AddDate(0, 0, 60)
+
+	dates := []*time.Time{nil, &past, &future, &farFuture}
+	bools := []bool{true, false}
+
+	for _, inProgress := range bools {
+		for _, hasCompletions := range bools {
+			for _, dueDate := range dates {
+				for _, nextDueDate := range dates {
+					task := &models.Task{
+						IsCancelled: false, // not cancelled
+						IsArchived:  true,  // always archived
+						InProgress:  inProgress,
+						DueDate:     dueDate,
+						NextDueDate: nextDueDate,
+					}
+					if hasCompletions {
+						task.Completions = []models.TaskCompletion{
+							{BaseModel: models.BaseModel{ID: 1}},
+						}
+					} else {
+						task.Completions = []models.TaskCompletion{}
+					}
+
+					result := categorization.CategorizeTaskWithTime(task, daysThreshold, now)
+
+					assert.Equal(t, categorization.ColumnCancelled, result,
+						"archived (non-cancelled) task should always map to ColumnCancelled, got %q "+
+							"(inProgress=%v completions=%v dueDate=%v nextDueDate=%v)",
+						result, inProgress, hasCompletions, dueDate, nextDueDate)
+				}
+			}
+		}
+	}
+}

internal/testutil/testutil.go

@@ -208,6 +208,7 @@ func CreateTestTask(t *testing.T, db *gorm.DB, residenceID, createdByID uint, ti
 		Title:       title,
 		IsCancelled: false,
 		IsArchived:  false,
+		Version:     1,
 	}
 	err := db.Create(task).Error
 	require.NoError(t, err)

internal/worker/jobs/handler.go

@@ -542,6 +542,11 @@ func NewSendPushTask(userID uint, title, message string, data map[string]string)
 // 2. Users who created a residence 5+ days ago but haven't created any tasks
 // Each email type is only sent once per user, ever.
 func (h *Handler) HandleOnboardingEmails(ctx context.Context, task *asynq.Task) error {
+	if !h.config.Features.OnboardingEmailsEnabled {
+		log.Debug().Msg("Onboarding emails disabled by feature flag, skipping")
+		return nil
+	}
+
 	log.Info().Msg("Processing onboarding emails...")
 
 	if h.onboardingService == nil {

migrations/000012_webhook_event_log.down.sql

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS webhook_event_log;

migrations/000012_webhook_event_log.up.sql

@@ -0,0 +1,9 @@
+CREATE TABLE IF NOT EXISTS webhook_event_log (
+    id SERIAL PRIMARY KEY,
+    event_id VARCHAR(255) NOT NULL,
+    provider VARCHAR(20) NOT NULL,
+    event_type VARCHAR(100) NOT NULL,
+    processed_at TIMESTAMPTZ DEFAULT NOW(),
+    payload_hash VARCHAR(64),
+    UNIQUE(provider, event_id)
+);

migrations/000013_business_constraints.down.sql

@@ -0,0 +1,5 @@
+ALTER TABLE notifications_notificationpreference DROP CONSTRAINT IF EXISTS uq_notif_pref_user;
+ALTER TABLE subscriptions_usersubscription DROP CONSTRAINT IF EXISTS uq_subscription_user;
+ALTER TABLE notifications_notification DROP CONSTRAINT IF EXISTS chk_notification_sent_consistency;
+ALTER TABLE subscriptions_usersubscription DROP CONSTRAINT IF EXISTS chk_subscription_tier;
+ALTER TABLE task_task DROP CONSTRAINT IF EXISTS chk_task_not_cancelled_and_archived;

migrations/000013_business_constraints.up.sql

@@ -0,0 +1,19 @@
+-- Prevent task from being both cancelled and archived simultaneously
+ALTER TABLE task_task ADD CONSTRAINT chk_task_not_cancelled_and_archived
+    CHECK (NOT (is_cancelled = true AND is_archived = true));
+
+-- Subscription tier must be a valid value
+ALTER TABLE subscriptions_usersubscription ADD CONSTRAINT chk_subscription_tier
+    CHECK (tier IN ('free', 'pro'));
+
+-- Notification: sent_at must be set when sent is true
+ALTER TABLE notifications_notification ADD CONSTRAINT chk_notification_sent_consistency
+    CHECK ((sent = false) OR (sent = true AND sent_at IS NOT NULL));
+
+-- One subscription per user
+ALTER TABLE subscriptions_usersubscription ADD CONSTRAINT uq_subscription_user
+    UNIQUE (user_id);
+
+-- One notification preference per user
+ALTER TABLE notifications_notificationpreference ADD CONSTRAINT uq_notif_pref_user
+    UNIQUE (user_id);

migrations/000014_task_version_column.down.sql

@@ -0,0 +1 @@
+ALTER TABLE task_task DROP COLUMN IF EXISTS version;

migrations/000014_task_version_column.up.sql

@@ -0,0 +1 @@
+ALTER TABLE task_task ADD COLUMN IF NOT EXISTS version INTEGER NOT NULL DEFAULT 1;

migrations/000015_targeted_indexes.down.sql

@@ -0,0 +1,3 @@
+DROP INDEX IF EXISTS idx_document_residence_active;
+DROP INDEX IF EXISTS idx_notification_user_unread;
+DROP INDEX IF EXISTS idx_task_kanban_query;

migrations/000015_targeted_indexes.up.sql

@@ -0,0 +1,14 @@
+-- Kanban: composite partial index for active task queries by residence with due date ordering
+CREATE INDEX IF NOT EXISTS idx_task_kanban_query
+    ON task_task (residence_id, next_due_date, due_date)
+    WHERE is_cancelled = false AND is_archived = false;
+
+-- Notifications: partial index for unread count (hot query)
+CREATE INDEX IF NOT EXISTS idx_notification_user_unread
+    ON notifications_notification (user_id, read)
+    WHERE read = false;
+
+-- Documents: partial index for active documents by residence
+CREATE INDEX IF NOT EXISTS idx_document_residence_active
+    ON documents_document (residence_id, is_active)
+    WHERE is_active = true;

migrations/012_webhook_event_log.down.sql

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS webhook_event_log;

migrations/012_webhook_event_log.up.sql

@@ -0,0 +1,9 @@
+CREATE TABLE IF NOT EXISTS webhook_event_log (
+    id SERIAL PRIMARY KEY,
+    event_id VARCHAR(255) NOT NULL,
+    provider VARCHAR(20) NOT NULL,
+    event_type VARCHAR(100) NOT NULL,
+    processed_at TIMESTAMPTZ DEFAULT NOW(),
+    payload_hash VARCHAR(64),
+    UNIQUE(provider, event_id)
+);

migrations/013_business_constraints.down.sql

@@ -0,0 +1,5 @@
+ALTER TABLE task_task DROP CONSTRAINT IF EXISTS chk_task_not_cancelled_and_archived;
+ALTER TABLE subscriptions_usersubscription DROP CONSTRAINT IF EXISTS chk_subscription_tier;
+ALTER TABLE notifications_notification DROP CONSTRAINT IF EXISTS chk_notification_sent_consistency;
+ALTER TABLE subscriptions_usersubscription DROP CONSTRAINT IF EXISTS uq_subscription_user;
+ALTER TABLE notifications_notificationpreference DROP CONSTRAINT IF EXISTS uq_notif_pref_user;

migrations/013_business_constraints.up.sql

@@ -0,0 +1,31 @@
+-- Prevent task from being both cancelled and archived simultaneously
+ALTER TABLE task_task ADD CONSTRAINT chk_task_not_cancelled_and_archived
+    CHECK (NOT (is_cancelled = true AND is_archived = true));
+
+-- Subscription tier must be valid
+ALTER TABLE subscriptions_usersubscription ADD CONSTRAINT chk_subscription_tier
+    CHECK (tier IN ('free', 'pro'));
+
+-- Notification: sent_at must be set if sent is true
+ALTER TABLE notifications_notification ADD CONSTRAINT chk_notification_sent_consistency
+    CHECK ((sent = false) OR (sent = true AND sent_at IS NOT NULL));
+
+-- One subscription per user
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM pg_constraint WHERE conname = 'uq_subscription_user'
+    ) THEN
+        ALTER TABLE subscriptions_usersubscription ADD CONSTRAINT uq_subscription_user UNIQUE (user_id);
+    END IF;
+END $$;
+
+-- One notification preference per user
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM pg_constraint WHERE conname = 'uq_notif_pref_user'
+    ) THEN
+        ALTER TABLE notifications_notificationpreference ADD CONSTRAINT uq_notif_pref_user UNIQUE (user_id);
+    END IF;
+END $$;

migrations/014_task_version_column.down.sql

@@ -0,0 +1 @@
+ALTER TABLE task_task DROP COLUMN IF EXISTS version;

migrations/014_task_version_column.up.sql

@@ -0,0 +1 @@
+ALTER TABLE task_task ADD COLUMN IF NOT EXISTS version INTEGER NOT NULL DEFAULT 1;

migrations/015_targeted_indexes.down.sql

@@ -0,0 +1,3 @@
+DROP INDEX IF EXISTS idx_task_kanban_query;
+DROP INDEX IF EXISTS idx_notification_user_unread;
+DROP INDEX IF EXISTS idx_document_residence_active;

migrations/015_targeted_indexes.up.sql

@@ -0,0 +1,14 @@
+-- Kanban: composite index for active task queries by residence with due date ordering
+CREATE INDEX IF NOT EXISTS idx_task_kanban_query
+    ON task_task (residence_id, is_cancelled, is_archived, next_due_date, due_date)
+    WHERE is_cancelled = false AND is_archived = false;
+
+-- Notifications: index for unread count (hot query)
+CREATE INDEX IF NOT EXISTS idx_notification_user_unread
+    ON notifications_notification (user_id, read)
+    WHERE read = false;
+
+-- Documents: residence + active filter
+CREATE INDEX IF NOT EXISTS idx_document_residence_active
+    ON documents_document (residence_id, is_active)
+    WHERE is_active = true;