refactor: event-driven delivery engine with channel notifications and timer-based retries

Replace the polling-based delivery engine with a fully event-driven architecture using Go channels and goroutines: - Webhook handler notifies engine via buffered channel after creating delivery records, with inline event data for payloads < 16KB - Large payloads (>= 16KB) use pointer semantics (Body *string = nil) and are fetched from DB on demand, keeping channel memory bounded - Failed retry-target deliveries schedule Go timers with exponential backoff; timers fire into a separate retry channel when ready - On startup, engine scans DB once to recover interrupted deliveries (pending processed immediately, retrying get timers for remaining backoff) - DB stores delivery status for crash recovery only, not for inter-component communication during normal operation - delivery.Notifier interface decouples handlers from engine; fx wires *Engine as Notifier No more periodic polling. No more wasted cycles when idle.
2026-03-01 21:46:16 -08:00 · 2026-03-01 21:46:16 -08:00 · 5e683af2a4
commit 5e683af2a4
parent 8f62fde8e9
6 changed files with 404 additions and 53 deletions
--- a/README.md
+++ b/README.md
@ -463,11 +463,12 @@ External Service
                     1. Look up Entrypoint by UUID
                     2. Capture full request as Event
                     3. Queue Delivery to each active Target
+                     4. Notify Engine via channel
                                                │
                                                ▼
                                        ┌──────────────┐
-                                        │  Delivery    │
-                                        │  Engine      │
+                                        │  Delivery    │◄── retry timers
+                                        │  Engine      │    (backoff)
                                        └──────┬───────┘
                                               │
                          ┌────────────────────┼────────────────────┐
@ -577,7 +578,7 @@ webhooker/
 │   ├── globals/
 │   │   └── globals.go         # Build-time variables (appname, version, arch)
 │   ├── delivery/
-│   │   └── engine.go          # Background delivery engine (fx lifecycle)
+│   │   └── engine.go          # Event-driven delivery engine (channel + timer based)
 │   ├── handlers/
 │   │   ├── handlers.go        # Base handler struct, JSON helpers, template rendering
 │   │   ├── auth.go            # Login, logout handlers
@ -627,11 +628,14 @@ Components are wired via Uber fx in this order:
 7. `session.New` — Cookie-based session manager
 8. `handlers.New` — HTTP handlers
 9. `middleware.New` — HTTP middleware
-10. `delivery.New` — Background delivery engine
-11. `server.New` — HTTP server and router
+10. `delivery.New` — Event-driven delivery engine
+11. `delivery.Engine` → `handlers.DeliveryNotifier` — interface bridge
+12. `server.New` — HTTP server and router

 The server starts via `fx.Invoke(func(*server.Server, *delivery.Engine)
-{})` which triggers the fx lifecycle hooks in dependency order.
+{})` which triggers the fx lifecycle hooks in dependency order. The
+`DeliveryNotifier` interface allows the webhook handler to notify the
+delivery engine of new work without a direct package dependency.

 ### Middleware Stack

@ -720,7 +724,7 @@ linted, tested, and compiled.
 - [x] Per-webhook database lifecycle management (create on webhook
      creation, delete on webhook removal)
 - [x] `WebhookDBManager` component with lazy connection pooling
- [x] Delivery engine polls all per-webhook DBs for pending deliveries
+- [x] Event-driven delivery engine (channel notifications + timer-based retries)
 - [x] Database target type marks delivery as immediately successful
      (events are already in the per-webhook DB)

--- a/cmd/webhooker/main.go
+++ b/cmd/webhooker/main.go
@ -39,6 +39,9 @@ func main() {
 			handlers.New,
 			middleware.New,
 			delivery.New,
+			// Wire *delivery.Engine as delivery.Notifier so the
+			// webhook handler can notify the engine of new deliveries.
+			func(e *delivery.Engine) delivery.Notifier { return e },
 			server.New,
 		),
 		fx.Invoke(func(*server.Server, *delivery.Engine) {}),
--- a/internal/delivery/engine.go
+++ b/internal/delivery/engine.go
@ -18,8 +18,19 @@ import (
 )

 const (
-	// pollInterval is how often the engine checks for pending deliveries.
-	pollInterval = 2 * time.Second
+	// notifyChannelSize is the buffer size for the delivery notification channel.
+	// Sized large enough that the webhook handler should never block.
+	notifyChannelSize = 1000
+
+	// retryChannelSize is the buffer size for the retry channel. Timer-fired
+	// retries are sent here for processing by the engine goroutine.
+	retryChannelSize = 1000
+
+	// MaxInlineBodySize is the maximum event body size that will be carried
+	// inline in a Notification through the channel. Bodies at or above this
+	// size are left nil and fetched from the per-webhook database on demand.
+	// This keeps channel buffer memory bounded under high traffic.
+	MaxInlineBodySize = 16 * 1024

 	// httpClientTimeout is the timeout for outbound HTTP requests.
 	httpClientTimeout = 30 * time.Second
@ -28,6 +39,33 @@ const (
 	maxBodyLog = 4096
 )

+// Notification carries event data through the delivery notification channel.
+// The Body field is a pointer: non-nil for payloads under MaxInlineBodySize
+// (16 KB), nil for larger payloads. When nil, the engine fetches the body
+// from the per-webhook database using EventID. This keeps channel buffer
+// memory bounded regardless of payload sizes during high traffic.
+type Notification struct {
+	WebhookID   string
+	EventID     string
+	Method      string
+	Headers     string
+	ContentType string
+	Body        *string // nil if body >= MaxInlineBodySize; fetch from DB by EventID
+}
+
+// Notifier is the interface for notifying the delivery engine about new
+// deliveries. Implemented by Engine and injected into handlers.
+type Notifier interface {
+	Notify(n Notification)
+}
+
+// retryRequest carries the information needed to retry a specific delivery.
+// Sent from timer goroutines to the engine's retry channel.
+type retryRequest struct {
+	webhookID  string
+	deliveryID string
+}
+
 // HTTPTargetConfig holds configuration for http and retry target types.
 type HTTPTargetConfig struct {
 	URL     string            `json:"url"`
@ -45,9 +83,14 @@ type EngineParams struct {
 	Logger    *logger.Logger
 }

-// Engine processes queued deliveries in the background.
-// It iterates over all active webhooks and polls each webhook's
-// per-webhook database for pending deliveries.
+// Engine processes queued deliveries in the background using an
+// event-driven architecture. New deliveries are signaled via a buffered
+// channel from the webhook handler and processed immediately. Failed
+// deliveries that need retry are scheduled via Go timers with exponential
+// backoff — each timer fires into a separate retry channel when the
+// backoff period expires. The database stores delivery status for crash
+// recovery only; on startup the engine scans for interrupted deliveries
+// and re-queues them.
 type Engine struct {
 	database  *database.Database
 	dbManager *database.WebhookDBManager
@ -55,6 +98,8 @@ type Engine struct {
 	client    *http.Client
 	cancel    context.CancelFunc
 	wg        sync.WaitGroup
+	notifyCh  chan Notification
+	retryCh   chan retryRequest
 }

 // New creates and registers the delivery engine with the fx lifecycle.
@ -66,6 +111,8 @@ func New(lc fx.Lifecycle, params EngineParams) *Engine {
 		client: &http.Client{
 			Timeout: httpClientTimeout,
 		},
+		notifyCh: make(chan Notification, notifyChannelSize),
+		retryCh:  make(chan retryRequest, retryChannelSize),
 	}

 	lc.Append(fx.Hook{
@ -97,29 +144,52 @@ func (e *Engine) stop() {
 	e.log.Info("delivery engine stopped")
 }

+// Notify signals the delivery engine that new deliveries are available.
+// This is called by the webhook handler after creating delivery records.
+// The notification carries the event data inline (with body pointer
+// semantics for memory efficiency). The call is non-blocking; if the
+// channel is full, a warning is logged and the deliveries will be
+// recovered on the next engine restart.
+func (e *Engine) Notify(n Notification) {
+	select {
+	case e.notifyCh <- n:
+	default:
+		e.log.Warn("delivery notification channel full, deliveries will be recovered on restart",
+			"webhook_id", n.WebhookID,
+			"event_id", n.EventID,
+		)
+	}
+}
+
 func (e *Engine) run(ctx context.Context) {
 	defer e.wg.Done()

-	ticker := time.NewTicker(pollInterval)
-	defer ticker.Stop()
+	// On startup, recover any pending or retrying deliveries that were
+	// interrupted by an unexpected shutdown. Pending deliveries are
+	// processed immediately; retrying deliveries get timers scheduled
+	// for their remaining backoff.
+	e.recoverInFlight(ctx)

 	for {
 		select {
 		case <-ctx.Done():
 			return
-		case <-ticker.C:
-			e.processPending(ctx)
+		case n := <-e.notifyCh:
+			e.processNotification(ctx, n)
+		case req := <-e.retryCh:
+			e.processRetryDelivery(ctx, req)
 		}
 	}
 }

-// processPending iterates over all active webhooks and processes pending
-// deliveries from each webhook's per-webhook database.
-func (e *Engine) processPending(ctx context.Context) {
-	// Get all active webhook IDs from the main application database
+// recoverInFlight scans all webhooks on startup for deliveries that were
+// interrupted by an unexpected shutdown. Pending deliveries are processed
+// immediately; retrying deliveries get timers scheduled for their
+// remaining backoff period.
+func (e *Engine) recoverInFlight(ctx context.Context) {
 	var webhookIDs []string
 	if err := e.database.DB().Model(&database.Webhook{}).Pluck("id", &webhookIDs).Error; err != nil {
-		e.log.Error("failed to query webhook IDs", "error", err)
+		e.log.Error("failed to query webhook IDs for recovery", "error", err)
 		return
 	}

@ -128,18 +198,200 @@ func (e *Engine) processPending(ctx context.Context) {
 		case <-ctx.Done():
 			return
 		default:
-			// Only process webhooks that have an event database file
-			if !e.dbManager.DBExists(webhookID) {
+		}
+
+		if !e.dbManager.DBExists(webhookID) {
+			continue
+		}
+
+		e.recoverWebhookDeliveries(ctx, webhookID)
+	}
+}
+
+// recoverWebhookDeliveries recovers pending and retrying deliveries for
+// a single webhook. Pending deliveries are processed directly (loading
+// event data from DB); retrying deliveries get timers scheduled based on
+// the elapsed time since the last attempt.
+func (e *Engine) recoverWebhookDeliveries(ctx context.Context, webhookID string) {
+	webhookDB, err := e.dbManager.GetDB(webhookID)
+	if err != nil {
+		e.log.Error("failed to get webhook database for recovery",
+			"webhook_id", webhookID,
+			"error", err,
+		)
+		return
+	}
+
+	// Check for pending deliveries and process them immediately
+	var pendingCount int64
+	webhookDB.Model(&database.Delivery{}).
+		Where("status = ?", database.DeliveryStatusPending).
+		Count(&pendingCount)
+
+	if pendingCount > 0 {
+		e.log.Info("recovering pending deliveries",
+			"webhook_id", webhookID,
+			"count", pendingCount,
+		)
+		e.processWebhookPendingDeliveries(ctx, webhookID)
+	}
+
+	// Schedule timers for retrying deliveries based on remaining backoff
+	var retrying []database.Delivery
+	if err := webhookDB.Where("status = ?", database.DeliveryStatusRetrying).
+		Find(&retrying).Error; err != nil {
+		e.log.Error("failed to query retrying deliveries for recovery",
+			"webhook_id", webhookID,
+			"error", err,
+		)
+		return
+	}
+
+	for i := range retrying {
+		d := &retrying[i]
+
+		var resultCount int64
+		webhookDB.Model(&database.DeliveryResult{}).
+			Where("delivery_id = ?", d.ID).
+			Count(&resultCount)
+		attemptNum := int(resultCount)
+
+		// Calculate remaining backoff from last attempt
+		remaining := time.Duration(0)
+
+		var lastResult database.DeliveryResult
+		if err := webhookDB.Where("delivery_id = ?", d.ID).
+			Order("created_at DESC").
+			First(&lastResult).Error; err == nil {
+			shift := attemptNum - 1
+			if shift < 0 {
+				shift = 0
+			}
+			if shift > 30 {
+				shift = 30
+			}
+			backoff := time.Duration(1<<uint(shift)) * time.Second //nolint:gosec // bounded above
+			elapsed := time.Since(lastResult.CreatedAt)
+			remaining = backoff - elapsed
+			if remaining < 0 {
+				remaining = 0
+			}
+		}
+
+		e.log.Info("recovering retrying delivery",
+			"webhook_id", webhookID,
+			"delivery_id", d.ID,
+			"attempt", attemptNum,
+			"remaining_backoff", remaining,
+		)
+
+		e.scheduleRetry(webhookID, d.ID, remaining)
+	}
+}
+
+// processNotification handles a delivery notification from the webhook
+// handler. It uses the inline event data from the notification (avoiding
+// a DB round-trip for the event) and only fetches the body from DB when
+// it was too large to carry inline (Body pointer is nil).
+func (e *Engine) processNotification(ctx context.Context, n Notification) {
+	webhookDB, err := e.dbManager.GetDB(n.WebhookID)
+	if err != nil {
+		e.log.Error("failed to get webhook database",
+			"webhook_id", n.WebhookID,
+			"error", err,
+		)
+		return
+	}
+
+	// Build the Event from the notification's inline data
+	event := database.Event{
+		Method:      n.Method,
+		Headers:     n.Headers,
+		ContentType: n.ContentType,
+	}
+	event.ID = n.EventID
+	event.WebhookID = n.WebhookID
+
+	if n.Body != nil {
+		event.Body = *n.Body
+	} else {
+		// Body was too large for inline transport — fetch from DB
+		var dbEvent database.Event
+		if err := webhookDB.Select("body").
+			First(&dbEvent, "id = ?", n.EventID).Error; err != nil {
+			e.log.Error("failed to fetch event body from database",
+				"event_id", n.EventID,
+				"error", err,
+			)
+			return
+		}
+		event.Body = dbEvent.Body
+	}
+
+	// Query pending deliveries for this specific event
+	var deliveries []database.Delivery
+	result := webhookDB.
+		Where("event_id = ? AND status = ?", n.EventID, database.DeliveryStatusPending).
+		Find(&deliveries)
+
+	if result.Error != nil {
+		e.log.Error("failed to query pending deliveries",
+			"webhook_id", n.WebhookID,
+			"event_id", n.EventID,
+			"error", result.Error,
+		)
+		return
+	}
+
+	if len(deliveries) == 0 {
+		return
+	}
+
+	// Collect unique target IDs and load targets from the main DB
+	seen := make(map[string]bool)
+	targetIDs := make([]string, 0, len(deliveries))
+	for _, d := range deliveries {
+		if !seen[d.TargetID] {
+			targetIDs = append(targetIDs, d.TargetID)
+			seen[d.TargetID] = true
+		}
+	}
+
+	var targets []database.Target
+	if err := e.database.DB().Where("id IN ?", targetIDs).Find(&targets).Error; err != nil {
+		e.log.Error("failed to load targets from main DB", "error", err)
+		return
+	}
+
+	targetMap := make(map[string]database.Target, len(targets))
+	for _, t := range targets {
+		targetMap[t.ID] = t
+	}
+
+	for i := range deliveries {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+			target, ok := targetMap[deliveries[i].TargetID]
+			if !ok {
+				e.log.Error("target not found for delivery",
+					"delivery_id", deliveries[i].ID,
+					"target_id", deliveries[i].TargetID,
+				)
 				continue
 			}
-			e.processWebhookDeliveries(ctx, webhookID)
+			deliveries[i].Event = event
+			deliveries[i].Target = target
+			e.processDelivery(ctx, webhookDB, &deliveries[i])
 		}
 	}
 }

-// processWebhookDeliveries polls a single webhook's database for pending
-// deliveries and processes them.
-func (e *Engine) processWebhookDeliveries(ctx context.Context, webhookID string) {
+// processWebhookPendingDeliveries queries a single webhook's database for
+// all pending deliveries and processes them. Used for crash recovery where
+// we don't have inline event data — everything is loaded from the DB.
+func (e *Engine) processWebhookPendingDeliveries(ctx context.Context, webhookID string) {
 	webhookDB, err := e.dbManager.GetDB(webhookID)
 	if err != nil {
 		e.log.Error("failed to get webhook database",
@ -149,14 +401,9 @@ func (e *Engine) processWebhookDeliveries(ctx context.Context, webhookID string)
 		return
 	}

-	// Query pending and retrying deliveries from the per-webhook DB.
-	// Preload Event (same DB) but NOT Target (Target is in the main DB).
 	var deliveries []database.Delivery
 	result := webhookDB.
-		Where("status IN ?", []database.DeliveryStatus{
-			database.DeliveryStatusPending,
-			database.DeliveryStatusRetrying,
-		}).
+		Where("status = ?", database.DeliveryStatusPending).
 		Preload("Event").
 		Find(&deliveries)

@ -212,6 +459,79 @@ func (e *Engine) processWebhookDeliveries(ctx context.Context, webhookID string)
 	}
 }

+// processRetryDelivery handles a single retry delivery triggered by a
+// backoff timer. It loads the delivery and target from the database and
+// re-attempts delivery.
+func (e *Engine) processRetryDelivery(ctx context.Context, req retryRequest) {
+	webhookDB, err := e.dbManager.GetDB(req.webhookID)
+	if err != nil {
+		e.log.Error("failed to get webhook database for retry",
+			"webhook_id", req.webhookID,
+			"delivery_id", req.deliveryID,
+			"error", err,
+		)
+		return
+	}
+
+	var d database.Delivery
+	if err := webhookDB.Preload("Event").
+		First(&d, "id = ?", req.deliveryID).Error; err != nil {
+		e.log.Error("failed to load delivery for retry",
+			"delivery_id", req.deliveryID,
+			"error", err,
+		)
+		return
+	}
+
+	// Verify delivery is still in retrying status (may have been
+	// cancelled or manually resolved while the timer was pending)
+	if d.Status != database.DeliveryStatusRetrying {
+		e.log.Debug("skipping retry for delivery no longer in retrying status",
+			"delivery_id", d.ID,
+			"status", d.Status,
+		)
+		return
+	}
+
+	// Load target from main DB
+	var target database.Target
+	if err := e.database.DB().First(&target, "id = ?", d.TargetID).Error; err != nil {
+		e.log.Error("failed to load target for retry",
+			"delivery_id", d.ID,
+			"target_id", d.TargetID,
+			"error", err,
+		)
+		return
+	}
+	d.Target = target
+
+	e.processDelivery(ctx, webhookDB, &d)
+}
+
+// scheduleRetry creates a Go timer that fires after the given delay and
+// sends a retry request to the engine's retry channel. This is the
+// mechanism for exponential backoff — no periodic DB scanning needed.
+func (e *Engine) scheduleRetry(webhookID, deliveryID string, delay time.Duration) {
+	e.log.Debug("scheduling delivery retry",
+		"webhook_id", webhookID,
+		"delivery_id", deliveryID,
+		"delay", delay,
+	)
+
+	time.AfterFunc(delay, func() {
+		select {
+		case e.retryCh <- retryRequest{
+			webhookID:  webhookID,
+			deliveryID: deliveryID,
+		}:
+		default:
+			e.log.Warn("retry channel full, delivery will be recovered on restart",
+				"delivery_id", deliveryID,
+			)
+		}
+	})
+}
+
 func (e *Engine) processDelivery(ctx context.Context, webhookDB *gorm.DB, d *database.Delivery) {
 	switch d.Target.Type {
 	case database.TargetTypeHTTP:
@ -277,24 +597,8 @@ func (e *Engine) deliverRetry(_ context.Context, webhookDB *gorm.DB, d *database
 	webhookDB.Model(&database.DeliveryResult{}).Where("delivery_id = ?", d.ID).Count(&resultCount)
 	attemptNum := int(resultCount) + 1

-	// Check if we should wait before retrying (exponential backoff)
-	if attemptNum > 1 {
-		var lastResult database.DeliveryResult
-		lookupErr := webhookDB.Where("delivery_id = ?", d.ID).Order("created_at DESC").First(&lastResult).Error
-		if lookupErr == nil {
-			shift := attemptNum - 2
-			if shift > 30 {
-				shift = 30
-			}
-			backoff := time.Duration(1<<uint(shift)) * time.Second //nolint:gosec // bounded above
-			nextAttempt := lastResult.CreatedAt.Add(backoff)
-			if time.Now().UTC().Before(nextAttempt) {
-				// Not time to retry yet
-				return
-			}
-		}
-	}
-
+	// Attempt delivery immediately — backoff is handled by the timer
+	// that triggered this call, not by polling.
 	statusCode, respBody, duration, err := e.doHTTPRequest(cfg, &d.Event)

 	success := err == nil && statusCode >= 200 && statusCode < 300
@ -319,6 +623,16 @@ func (e *Engine) deliverRetry(_ context.Context, webhookDB *gorm.DB, d *database
 		e.updateDeliveryStatus(webhookDB, d, database.DeliveryStatusFailed)
 	} else {
 		e.updateDeliveryStatus(webhookDB, d, database.DeliveryStatusRetrying)
+
+		// Schedule a timer for the next retry with exponential backoff.
+		// The timer will fire and send a retryRequest to the engine's
+		// retry channel, which triggers processRetryDelivery.
+		shift := attemptNum - 1
+		if shift > 30 {
+			shift = 30
+		}
+		backoff := time.Duration(1<<uint(shift)) * time.Second //nolint:gosec // bounded above
+		e.scheduleRetry(d.Event.WebhookID, d.ID, backoff)
 	}
 }

--- a/internal/handlers/handlers.go
+++ b/internal/handlers/handlers.go
@ -9,6 +9,7 @@ import (

 	"go.uber.org/fx"
 	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/delivery"
 	"sneak.berlin/go/webhooker/internal/globals"
 	"sneak.berlin/go/webhooker/internal/healthcheck"
 	"sneak.berlin/go/webhooker/internal/logger"
@ -25,6 +26,7 @@ type HandlersParams struct {
 	WebhookDBMgr *database.WebhookDBManager
 	Healthcheck  *healthcheck.Healthcheck
 	Session      *session.Session
+	Notifier     delivery.Notifier
 }

 type Handlers struct {
@ -34,6 +36,7 @@ type Handlers struct {
 	db        *database.Database
 	dbMgr     *database.WebhookDBManager
 	session   *session.Session
+	notifier  delivery.Notifier
 	templates map[string]*template.Template
 }

@ -57,6 +60,7 @@ func New(lc fx.Lifecycle, params HandlersParams) (*Handlers, error) {
 	s.db = params.Database
 	s.dbMgr = params.WebhookDBMgr
 	s.session = params.Session
+	s.notifier = params.Notifier

 	// Parse all page templates once at startup
 	s.templates = map[string]*template.Template{
--- a/internal/handlers/handlers_test.go
+++ b/internal/handlers/handlers_test.go
@ -12,12 +12,18 @@ import (
 	"go.uber.org/fx/fxtest"
 	"sneak.berlin/go/webhooker/internal/config"
 	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/delivery"
 	"sneak.berlin/go/webhooker/internal/globals"
 	"sneak.berlin/go/webhooker/internal/healthcheck"
 	"sneak.berlin/go/webhooker/internal/logger"
 	"sneak.berlin/go/webhooker/internal/session"
 )

+// noopNotifier is a no-op delivery.Notifier for tests.
+type noopNotifier struct{}
+
+func (n *noopNotifier) Notify(delivery.Notification) {}
+
 func TestHandleIndex(t *testing.T) {
 	var h *Handlers

@ -41,6 +47,7 @@ func TestHandleIndex(t *testing.T) {
 			database.NewWebhookDBManager,
 			healthcheck.New,
 			session.New,
+			func() delivery.Notifier { return &noopNotifier{} },
 			New,
 		),
 		fx.Populate(&h),
@ -76,6 +83,7 @@ func TestRenderTemplate(t *testing.T) {
 			database.NewWebhookDBManager,
 			healthcheck.New,
 			session.New,
+			func() delivery.Notifier { return &noopNotifier{} },
 			New,
 		),
 		fx.Populate(&h),
--- a/internal/handlers/webhook.go
+++ b/internal/handlers/webhook.go
@ -7,6 +7,7 @@ import (

 	"github.com/go-chi/chi"
 	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/delivery"
 )

 const (
@ -117,12 +118,12 @@ func (h *Handlers) HandleWebhook() http.HandlerFunc {

 		// Create delivery records for each active target
 		for i := range targets {
-			delivery := &database.Delivery{
+			dlv := &database.Delivery{
 				EventID:  event.ID,
 				TargetID: targets[i].ID,
 				Status:   database.DeliveryStatusPending,
 			}
-			if err := tx.Create(delivery).Error; err != nil {
+			if err := tx.Create(dlv).Error; err != nil {
 				tx.Rollback()
 				h.log.Error("failed to create delivery",
 					"target_id", targets[i].ID,
@ -139,6 +140,23 @@ func (h *Handlers) HandleWebhook() http.HandlerFunc {
 			return
 		}

+		// Notify the delivery engine with inline event data so it can
+		// process deliveries immediately without a DB round-trip.
+		// Large bodies (>= 16KB) are left nil to keep channel memory
+		// bounded; the engine fetches them from DB on demand.
+		n := delivery.Notification{
+			WebhookID:   entrypoint.WebhookID,
+			EventID:     event.ID,
+			Method:      event.Method,
+			Headers:     event.Headers,
+			ContentType: event.ContentType,
+		}
+		bodyStr := string(body)
+		if len(body) < delivery.MaxInlineBodySize {
+			n.Body = &bodyStr
+		}
+		h.notifier.Notify(n)
+
 		h.log.Info("webhook event created",
 			"event_id", event.ID,
 			"webhook_id", entrypoint.WebhookID,