feat: add receiver rate limiting (refs #64)

Refactors the delivery engine so each target TYPE is an implementation of a `Target` interface, dispatched from a registry, with each target owning its full delivery including durable retries. Implements the authoritative design from issue #77 (the corrected "hand the DB + Scheduler to the target" design).

## The new interface

```go
type Scheduler interface {
    ScheduleRetry(task Task, delay time.Duration)
}

type Target interface {
    Deliver(ctx context.Context, webhookDB *gorm.DB,
        d *database.Delivery, task *Task, sched Scheduler)
}
```

`Deliver` receives everything a target needs to be autonomous and durable: the request context, the per-webhook `*gorm.DB`, the `*database.Delivery`, the attempt `*Task`, and a `Scheduler` (the engine) for durable re-enqueue. The target makes one attempt, writes the `DeliveryResult`, updates `DeliveryStatus`, and — for retry targets — decides whether to retry, computes its own backoff, gates with its own circuit breaker, and reschedules via the injected `Scheduler`.

`processDelivery` collapses to a registry lookup (`map[database.TargetType]Target`) and a `Deliver` call; an unknown target type still fails the delivery as before.

## Per-target ownership

- `httpTarget` and `slackTarget` share a retry core (`httpCore`) that owns retry, exponential backoff, and the per-target circuit breaker. The core is fire-and-forget when `MaxRetries == 0` and adds breaker-gated backed-off retries when `MaxRetries > 0`. The per-attempt request differs (HTTP forwards the body + filtered headers; Slack posts a formatted message) and is supplied as a closure, so each keeps its exact recording semantics (e.g. HTTP records no error string for a non-2xx, Slack records `HTTP <code>`).
- `databaseTarget` and `logTarget` are fire-and-forget: they record a single successful attempt.

Moved wholesale into the http/slack targets: `deliverHTTP*`, `handleHTTPRetry`, `circuitBreakerBlock`, `calcBackoff` / `calcRemainingBackoff` / `backoffElapsed`, the circuit-breaker `sync.Map` + `getCircuitBreaker`, `clientForConfig`, `doHTTPRequest`, `applyRequestHeaders`, and the config parsers. The engine keeps `recordResult`, `updateDeliveryStatus`, and `ScheduleRetry`.

## Slack MaxRetries gating

Slack is now on the same shared core as HTTP, with retry + breaker gated on `MaxRetries`. A `MaxRetries` of 0 stays single-attempt fire-and-forget, so **every existing Slack target is unchanged**; a Slack target configured with retries gets backoff + circuit breaker.

## Log-target full content

`logTarget` now logs the ENTIRE inbound webhook — full request body and full request headers, plus method, content type, and the webhook id and entrypoint id — rather than a summary line. This supersedes the smaller log-summary work (#70).

## `Task.EntrypointID`

To carry the entrypoint id to the log target, `Task` gains an `EntrypointID` field, populated in the webhook handler's `buildDeliveryTasks`, the engine's recovery-task builder, and `buildEventFromTask`.

## Durability / recovery

The crash-durable async retry model is preserved unchanged: one attempt per worker turn; on failure the status is set `retrying`, backoff is computed, and the task is re-enqueued via `ScheduleRetry` (a `time.AfterFunc` onto the retry channel). On restart, `recoverRetryingDeliveries` and the 60s sweep hand each orphaned `retrying` delivery back to its target to recompute the remaining backoff and reschedule (targets that own retries implement an internal `rescheduler`; fire-and-forget targets, which never produce `retrying` deliveries, are skipped).

## How behaviour is preserved

No external behaviour changes except the two called out above (log target full content; Slack gaining `MaxRetries`-gated retries). All existing delivery tests pass with only their `export_test.go` wrappers re-pointed at the new structure — `ExportDeliverHTTP/Slack/Database/Log` now call the targets, `ExportGetCircuitBreaker` / `ExportClient` / `ExportClientForConfig` / `ExportDoHTTPRequest` resolve against the HTTP target's shared client and breaker map, and `ExportParseHTTPConfig` / `ExportParseSlackConfig` call the relocated free functions. Added: a `logTarget` test asserting the log line contains the full body, headers, and ids, and a Slack `MaxRetries`-gated retry test.

`docker build .` is green (fmt-check, lint, test, static build all pass).

Closes #77

Co-authored-by: sneak <sneak@sneak.berlin>
Reviewed-on: #81
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>

README.md

@@ -92,6 +92,7 @@ TTY detection, and security headers are always applied.
 | `METRICS_USERNAME`      | Basic auth username for `/metrics`  | `""`     |
 | `METRICS_PASSWORD`      | Basic auth password for `/metrics`  | `""`     |
 | `SENTRY_DSN`            | Sentry error reporting DSN          | `""`     |
+| `RECEIVER_RATE_LIMIT`   | Receiver requests/minute per IP per entrypoint | `120` |
 
 On first startup, webhooker automatically generates a cryptographically
 secure session encryption key and stores it in the database. This key
@@ -676,17 +677,24 @@ just delayed until the target is healthy again.
 
 ### Rate Limiting
 
-Global rate limiting middleware (e.g., per-IP throttling applied at the
+Global blanket rate limiting middleware (e.g., a per-IP throttle shared
-router level) **must not** apply to webhook receiver endpoints. Webhook
+with the web UI) **must not** apply to webhook receiver endpoints.
-endpoints receive automated traffic from external services at
+Webhook endpoints receive automated traffic from external services at
-unpredictable rates, and blanket rate limits would cause legitimate
+unpredictable rates, and blanket limits shared with other routes would
-deliveries to be dropped.
+cause legitimate deliveries to be dropped.
 
-Instead, each webhook has its own individually configurable rate limit,
+The receiver instead has its own dedicated abuse limit, scoped to the
-applied within the webhook handler itself. By default, no rate limit is
+`/webhook/{uuid}` route only and keyed per client IP per entrypoint: one
-applied — webhook endpoints accept traffic as fast as it arrives. Rate
+misbehaving sender is throttled without affecting other senders of the
-limits can be configured per-webhook when needed (e.g., to protect
+same entrypoint or the same sender's other entrypoints. The limit is
-against a misbehaving sender).
+`RECEIVER_RATE_LIMIT` requests per minute (default 120, generous for
+legitimate webhook senders). Requests over the limit receive HTTP 429
+with a `Retry-After` header. A set-but-invalid `RECEIVER_RATE_LIMIT`
+value aborts startup rather than silently falling back to the default.
+
+Finer-grained per-webhook rate limits (configured in the web UI and
+enforced in the webhook handler) can layer on top of this env-level
+abuse limit later; they are tracked as future work.
 
 ### API Endpoints
 

TODO.md

@@ -10,24 +10,27 @@
 
 # Status
 
-pre-1.0. No git tags exist. main (afe88c6) is a working webhook proxy
+pre-1.0. No git tags exist. main (81413c5) is a working webhook proxy
 with auth, CSRF/SSRF protections, login rate limiting, Slack target,
-policy compliance (#6), and pinned lint tooling (#55). Note: TODO.md was
+policy compliance (#6), pinned lint tooling (#55), a per-webhook event
-deliberately deleted from this repo in f9a9569 (2026-03-01, #6); its
+retention reaper (#63), and delivery targets behind a Target interface
-content was folded into the README TODO section, which this draft
+(#77). Work is tracked as Gitea issues (the authoritative TODO); this
-reconstructs as of 2026-07-06.
+file is a summary. Note: TODO.md was deliberately deleted from this
+repo in f9a9569 (2026-03-01, #6); its content was folded into the
+README TODO section, which this draft reconstructs as of 2026-07-06.
 
 # Next Step
 
-Implement automatic event retention cleanup based on retention_days: a
+Manual event redelivery from the web UI (replay is a core promised
-periodic maintenance job that deletes Events, Deliveries, and
+capability in the README rationale).
-DeliveryResults older than the parent webhook's retention_days from each
-per-webhook event database. The field exists on the Webhook model and
-the README promises the behavior, but nothing enforces it, so event
-databases currently grow without bound.
 
 # Completed Steps
 
+- 2026-08-07 Rate-limit the public webhook receiver per client IP per
+  entrypoint, env-configurable with fail-loud parsing (#64)
+- 2026-08-07 Per-webhook event retention reaper (#63); NoCache
+  middleware for authenticated pages (#61); Target interface refactor
+  (#77)
 - 2026-07-07 Adopted scripts-to-rule-them-all: `script/` entrypoints,
   Makefile shims, README Entrypoints section
 - 2026-03-25 pin golangci-lint Docker image for linting (#55)
@@ -51,12 +54,10 @@ databases currently grow without bound.
 
 # Future Steps
 
-- Manual event redelivery from the web UI (replay is a core promised
-  capability in the README rationale)
 - Delivery status and retry management UI
 - Per-webhook rate limiting in the receiver handler (per-webhook config
-  plus handler enforcement; global limits must not apply to receiver
+  plus handler enforcement, layered on the env-level receiver limit
-  endpoints)
+  from #64; global limits must not apply to receiver endpoints)
 - Webhook signature verification for GitHub and Stripe HMAC formats
 - API key authentication for programmatic access (APIKey model exists;
   Bearer token middleware does not)

cmd/webhooker/main.go

@@ -34,6 +34,7 @@ func main() {
 			config.New,
 			database.New,
 			database.NewWebhookDBManager,
+			database.NewRetentionReaper,
 			healthcheck.New,
 			session.New,
 			handlers.New,
@@ -44,6 +45,13 @@ func main() {
 			func(e *delivery.Engine) delivery.Notifier { return e },
 			server.New,
 		),
-		fx.Invoke(func(*server.Server, *delivery.Engine) {}),
+		fx.Invoke(
+			func(
+				*server.Server,
+				*delivery.Engine,
+				*database.RetentionReaper,
+			) {
+			},
+		),
 	).Run()
 }

internal/config/config.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"time"
 
 	"go.uber.org/fx"
 	"sneak.berlin/go/webhooker/internal/globals"
@@ -26,12 +27,27 @@ const (
 
 	// defaultPort is the default HTTP listen port.
 	defaultPort = 8080
+
+	// defaultRetentionSweepInterval is how often the retention
+	// reaper deletes events older than each webhook's RetentionDays.
+	defaultRetentionSweepInterval = time.Hour
+
+	// defaultReceiverRateLimit is the default number of requests
+	// per minute each client IP may send to a single webhook
+	// receiver entrypoint. Generous for legitimate webhook
+	// senders while bounding abuse of the one unauthenticated,
+	// internet-exposed endpoint.
+	defaultReceiverRateLimit = 120
 )
 
 // ErrInvalidEnvironment is returned when WEBHOOKER_ENVIRONMENT
 // contains an unrecognised value.
 var ErrInvalidEnvironment = errors.New("invalid environment")
 
+// ErrNonPositiveValue is returned when an environment variable that
+// requires a positive integer is set to zero or a negative number.
+var ErrNonPositiveValue = errors.New("value must be positive")
+
 //nolint:revive // ConfigParams is a standard fx naming convention.
 type ConfigParams struct {
 	fx.In
@@ -51,8 +67,16 @@ type Config struct {
 	MetricsUsername string
 	Port            int
 	SentryDSN       string
-	params          *ConfigParams
+
-	log             *slog.Logger
+	// RetentionSweepInterval is how often the retention reaper runs.
+	RetentionSweepInterval time.Duration
+
+	// ReceiverRateLimit is the number of requests per minute each
+	// client IP may send to a single webhook receiver entrypoint.
+	ReceiverRateLimit int
+
+	params *ConfigParams
+	log    *slog.Logger
 }
 
 // IsDev returns true if running in development environment.
@@ -95,6 +119,62 @@ func envInt(key string, defaultValue int) int {
 	return defaultValue
 }
 
+// envPositiveInt returns the value of the named environment variable
+// parsed as a positive integer. Returns defaultValue if not set. If
+// the variable is set but cannot be parsed, or parses to less than
+// one, it returns a wrapped error naming the key and the bad value,
+// so startup fails loudly rather than silently falling back to the
+// default.
+func envPositiveInt(
+	key string,
+	defaultValue int,
+) (int, error) {
+	v := os.Getenv(key)
+	if v == "" {
+		return defaultValue, nil
+	}
+
+	i, err := strconv.Atoi(v)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"invalid integer for %s: %q: %w", key, v, err,
+		)
+	}
+
+	if i < 1 {
+		return 0, fmt.Errorf(
+			"%w: %s must be at least 1, got %q",
+			ErrNonPositiveValue, key, v,
+		)
+	}
+
+	return i, nil
+}
+
+// envDuration returns the value of the named environment variable
+// parsed as a Go duration (e.g. "1h", "30m"). Returns defaultValue if
+// not set. If the variable is set but cannot be parsed, it returns a
+// wrapped error naming the key and the bad value, so startup fails
+// loudly rather than silently falling back to the default.
+func envDuration(
+	key string,
+	defaultValue time.Duration,
+) (time.Duration, error) {
+	v := os.Getenv(key)
+	if v == "" {
+		return defaultValue, nil
+	}
+
+	d, err := time.ParseDuration(v)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"invalid duration for %s: %q: %w", key, v, err,
+		)
+	}
+
+	return d, nil
+}
+
 // New creates a Config by reading environment variables.
 //
 //nolint:revive // lc parameter is required by fx even if unused.
@@ -118,18 +198,42 @@ func New(lc fx.Lifecycle, params ConfigParams) (*Config, error) {
 		)
 	}
 
+	// Parse the retention sweep interval; a set-but-unparseable value
+	// is a hard error so fx aborts startup rather than silently using
+	// the default.
+	retentionSweepInterval, err := envDuration(
+		"RETENTION_SWEEP_INTERVAL",
+		defaultRetentionSweepInterval,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	// Parse the receiver rate limit; a set-but-unparseable or
+	// non-positive value is a hard error so fx aborts startup
+	// rather than silently using the default.
+	receiverRateLimit, err := envPositiveInt(
+		"RECEIVER_RATE_LIMIT",
+		defaultReceiverRateLimit,
+	)
+	if err != nil {
+		return nil, err
+	}
+
 	// Load configuration values from environment variables
 	s := &Config{
-		DataDir:         envString("DATA_DIR"),
+		DataDir:                envString("DATA_DIR"),
-		Debug:           envBool("DEBUG", false),
+		Debug:                  envBool("DEBUG", false),
-		MaintenanceMode: envBool("MAINTENANCE_MODE", false),
+		MaintenanceMode:        envBool("MAINTENANCE_MODE", false),
-		Environment:     environment,
+		Environment:            environment,
-		MetricsUsername: envString("METRICS_USERNAME"),
+		MetricsUsername:        envString("METRICS_USERNAME"),
-		MetricsPassword: envString("METRICS_PASSWORD"),
+		MetricsPassword:        envString("METRICS_PASSWORD"),
-		Port:            envInt("PORT", defaultPort),
+		Port:                   envInt("PORT", defaultPort),
-		SentryDSN:       envString("SENTRY_DSN"),
+		SentryDSN:              envString("SENTRY_DSN"),
-		log:             log,
+		RetentionSweepInterval: retentionSweepInterval,
-		params:          &params,
+		ReceiverRateLimit:      receiverRateLimit,
+		log:                    log,
+		params:                 &params,
 	}
 
 	// Set default DataDir. All SQLite databases (main application
@@ -151,6 +255,8 @@ func New(lc fx.Lifecycle, params ConfigParams) (*Config, error) {
 		"debug", s.Debug,
 		"maintenanceMode", s.MaintenanceMode,
 		"dataDir", s.DataDir,
+		"retentionSweepInterval", s.RetentionSweepInterval.String(),
+		"receiverRateLimit", s.ReceiverRateLimit,
 		"hasSentryDSN", s.SentryDSN != "",
 		"hasMetricsAuth",
 		s.MetricsUsername != "" && s.MetricsPassword != "",

internal/config/config_test.go

@@ -3,6 +3,7 @@ package config_test
 import (
 	"os"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -120,6 +121,100 @@ func testEnvironmentConfigSuccess(
 	assert.Equal(t, isProd, cfg.IsProd())
 }
 
+func TestRetentionSweepInterval(t *testing.T) {
+	tests := []struct {
+		name        string
+		set         bool
+		value       string
+		expectError bool
+		expected    time.Duration
+	}{
+		{
+			name:     "unset uses default",
+			set:      false,
+			expected: time.Hour,
+		},
+		{
+			name:     "valid value is parsed",
+			set:      true,
+			value:    "15m",
+			expected: 15 * time.Minute,
+		},
+		{
+			name:        "unparseable value fails startup",
+			set:         true,
+			value:       "not-a-duration",
+			expectError: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Cannot use t.Parallel() here because t.Setenv
+			// is incompatible with parallel subtests.
+			t.Setenv("WEBHOOKER_ENVIRONMENT", "dev")
+
+			if tt.set {
+				t.Setenv("RETENTION_SWEEP_INTERVAL", tt.value)
+			} else {
+				require.NoError(t, os.Unsetenv(
+					"RETENTION_SWEEP_INTERVAL",
+				))
+			}
+
+			if tt.expectError {
+				testRetentionSweepIntervalError(t)
+			} else {
+				testRetentionSweepIntervalSuccess(t, tt.expected)
+			}
+		})
+	}
+}
+
+func testRetentionSweepIntervalError(t *testing.T) {
+	t.Helper()
+
+	var cfg *config.Config
+
+	app := fx.New(
+		fx.NopLogger,
+		fx.Provide(
+			globals.New,
+			logger.New,
+			config.New,
+		),
+		fx.Populate(&cfg),
+	)
+
+	assert.Error(t, app.Err())
+}
+
+func testRetentionSweepIntervalSuccess(
+	t *testing.T,
+	expected time.Duration,
+) {
+	t.Helper()
+
+	var cfg *config.Config
+
+	app := fxtest.New(
+		t,
+		fx.Provide(
+			globals.New,
+			logger.New,
+			config.New,
+		),
+		fx.Populate(&cfg),
+	)
+	require.NoError(t, app.Err())
+
+	app.RequireStart()
+
+	defer app.RequireStop()
+
+	assert.Equal(t, expected, cfg.RetentionSweepInterval)
+}
+
 func TestDefaultDataDir(t *testing.T) {
 	for _, env := range []string{"", "dev", "prod"} {
 		name := env
@@ -163,3 +258,109 @@ func TestDefaultDataDir(t *testing.T) {
 		})
 	}
 }
+
+func TestReceiverRateLimit(t *testing.T) {
+	tests := []struct {
+		name        string
+		set         bool
+		value       string
+		expectError bool
+		expected    int
+	}{
+		{
+			name:     "unset uses default",
+			set:      false,
+			expected: 120,
+		},
+		{
+			name:     "valid value is parsed",
+			set:      true,
+			value:    "30",
+			expected: 30,
+		},
+		{
+			name:        "unparseable value fails startup",
+			set:         true,
+			value:       "not-a-number",
+			expectError: true,
+		},
+		{
+			name:        "zero fails startup",
+			set:         true,
+			value:       "0",
+			expectError: true,
+		},
+		{
+			name:        "negative fails startup",
+			set:         true,
+			value:       "-5",
+			expectError: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Cannot use t.Parallel() here because t.Setenv
+			// is incompatible with parallel subtests.
+			t.Setenv("WEBHOOKER_ENVIRONMENT", "dev")
+
+			if tt.set {
+				t.Setenv("RECEIVER_RATE_LIMIT", tt.value)
+			} else {
+				require.NoError(t, os.Unsetenv(
+					"RECEIVER_RATE_LIMIT",
+				))
+			}
+
+			if tt.expectError {
+				testReceiverRateLimitError(t)
+			} else {
+				testReceiverRateLimitSuccess(t, tt.expected)
+			}
+		})
+	}
+}
+
+func testReceiverRateLimitError(t *testing.T) {
+	t.Helper()
+
+	var cfg *config.Config
+
+	app := fx.New(
+		fx.NopLogger,
+		fx.Provide(
+			globals.New,
+			logger.New,
+			config.New,
+		),
+		fx.Populate(&cfg),
+	)
+
+	assert.Error(t, app.Err())
+}
+
+func testReceiverRateLimitSuccess(
+	t *testing.T,
+	expected int,
+) {
+	t.Helper()
+
+	var cfg *config.Config
+
+	app := fxtest.New(
+		t,
+		fx.Provide(
+			globals.New,
+			logger.New,
+			config.New,
+		),
+		fx.Populate(&cfg),
+	)
+	require.NoError(t, app.Err())
+
+	app.RequireStart()
+
+	defer app.RequireStop()
+
+	assert.Equal(t, expected, cfg.ReceiverRateLimit)
+}

internal/database/export_test.go

@@ -0,0 +1,31 @@
+package database
+
+import (
+	"context"
+	"log/slog"
+	"os"
+	"time"
+)
+
+// NewTestRetentionReaper builds a RetentionReaper backed by the given
+// main database and per-webhook database manager, without the fx
+// lifecycle. Intended for tests.
+func NewTestRetentionReaper(
+	db *Database,
+	mgr *WebhookDBManager,
+) *RetentionReaper {
+	return &RetentionReaper{
+		db:        db,
+		dbManager: mgr,
+		log: slog.New(slog.NewTextHandler(
+			os.Stderr,
+			&slog.HandlerOptions{Level: slog.LevelDebug},
+		)),
+		interval: time.Hour,
+	}
+}
+
+// ExportSweep runs a single retention sweep synchronously for tests.
+func (r *RetentionReaper) ExportSweep(ctx context.Context) {
+	r.sweep(ctx)
+}

internal/database/retention.go

@@ -0,0 +1,252 @@
+package database
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"sync"
+	"time"
+
+	"go.uber.org/fx"
+	"gorm.io/gorm"
+	"sneak.berlin/go/webhooker/internal/config"
+	"sneak.berlin/go/webhooker/internal/logger"
+)
+
+// hoursPerDay converts a RetentionDays count into hours for cutoff
+// computation.
+const hoursPerDay = 24
+
+// RetentionReaperParams holds the fx dependencies for the
+// RetentionReaper.
+type RetentionReaperParams struct {
+	fx.In
+
+	Config    *config.Config
+	Database  *Database
+	DBManager *WebhookDBManager
+	Logger    *logger.Logger
+}
+
+// RetentionReaper periodically deletes expired events (and their
+// dependent deliveries and delivery results) from each per-webhook
+// database, enforcing every webhook's RetentionDays. Rows are removed
+// permanently so that per-webhook SQLite files do not grow without
+// bound.
+type RetentionReaper struct {
+	db        *Database
+	dbManager *WebhookDBManager
+	log       *slog.Logger
+	interval  time.Duration
+	cancel    context.CancelFunc
+	wg        sync.WaitGroup
+}
+
+// NewRetentionReaper creates the retention reaper and registers its
+// fx lifecycle hooks. The background sweep loop starts on OnStart and
+// stops cleanly on OnStop via context cancellation.
+func NewRetentionReaper(
+	lc fx.Lifecycle,
+	params RetentionReaperParams,
+) *RetentionReaper {
+	r := &RetentionReaper{
+		db:        params.Database,
+		dbManager: params.DBManager,
+		log:       params.Logger.Get(),
+		interval:  params.Config.RetentionSweepInterval,
+	}
+
+	lc.Append(fx.Hook{
+		OnStart: func(ctx context.Context) error {
+			r.start(ctx)
+
+			return nil
+		},
+		OnStop: func(_ context.Context) error {
+			r.stop()
+
+			return nil
+		},
+	})
+
+	return r
+}
+
+func (r *RetentionReaper) start(ctx context.Context) {
+	ctx, cancel := context.WithCancel(ctx)
+	r.cancel = cancel
+
+	r.wg.Add(1)
+
+	go r.run(ctx)
+
+	r.log.Info(
+		"retention reaper started",
+		"interval", r.interval.String(),
+	)
+}
+
+func (r *RetentionReaper) stop() {
+	r.log.Info("retention reaper stopping")
+
+	if r.cancel != nil {
+		r.cancel()
+	}
+
+	r.wg.Wait()
+	r.log.Info("retention reaper stopped")
+}
+
+func (r *RetentionReaper) run(ctx context.Context) {
+	defer r.wg.Done()
+
+	ticker := time.NewTicker(r.interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			r.sweep(ctx)
+		}
+	}
+}
+
+// sweep lists every webhook from the main database and reaps expired
+// rows from each per-webhook database whose RetentionDays is positive.
+func (r *RetentionReaper) sweep(ctx context.Context) {
+	var webhooks []Webhook
+
+	err := r.db.DB().
+		Model(&Webhook{}).
+		Find(&webhooks).Error
+	if err != nil {
+		r.log.Error(
+			"retention sweep: failed to list webhooks",
+			"error", err,
+		)
+
+		return
+	}
+
+	for i := range webhooks {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+
+		wh := webhooks[i]
+
+		// RetentionDays of zero or less means retain forever.
+		if wh.RetentionDays <= 0 {
+			continue
+		}
+
+		// Nothing to reap if the per-webhook database has never
+		// been created.
+		if !r.dbManager.DBExists(wh.ID) {
+			continue
+		}
+
+		r.reapWebhook(wh.ID, wh.RetentionDays)
+	}
+}
+
+// reapWebhook removes every expired event (and its dependents) from a
+// single webhook's database.
+func (r *RetentionReaper) reapWebhook(
+	webhookID string,
+	retentionDays int,
+) {
+	db, err := r.dbManager.GetDB(webhookID)
+	if err != nil {
+		r.log.Error(
+			"retention sweep: failed to open webhook database",
+			"webhook_id", webhookID,
+			"error", err,
+		)
+
+		return
+	}
+
+	cutoff := time.Now().Add(
+		-time.Duration(retentionDays*hoursPerDay) * time.Hour,
+	)
+
+	deleted, err := reapExpired(db, cutoff)
+	if err != nil {
+		r.log.Error(
+			"retention sweep: failed to reap expired events",
+			"webhook_id", webhookID,
+			"error", err,
+		)
+
+		return
+	}
+
+	if deleted > 0 {
+		r.log.Info(
+			"retention sweep: reaped expired events",
+			"webhook_id", webhookID,
+			"retention_days", retentionDays,
+			"events_deleted", deleted,
+		)
+	}
+}
+
+// reapExpired hard-deletes, in foreign-key-safe order, the delivery
+// results, deliveries, and events associated with events older than
+// cutoff. Deletes are unscoped so rows are physically removed rather
+// than soft-deleted, reclaiming disk. It returns the number of events
+// deleted.
+func reapExpired(db *gorm.DB, cutoff time.Time) (int64, error) {
+	// Fresh subqueries are built per statement to avoid reusing a
+	// mutated builder across executions.
+	expiredEventIDs := func() *gorm.DB {
+		return db.Model(&Event{}).
+			Select("id").
+			Where("created_at < ?", cutoff)
+	}
+	expiredDeliveryIDs := func() *gorm.DB {
+		return db.Model(&Delivery{}).
+			Select("id").
+			Where("event_id IN (?)", expiredEventIDs())
+	}
+
+	// 1. Delivery results whose delivery belongs to an expired event.
+	res := db.Unscoped().
+		Where("delivery_id IN (?)", expiredDeliveryIDs()).
+		Delete(&DeliveryResult{})
+	if res.Error != nil {
+		return 0, fmt.Errorf(
+			"deleting expired delivery results: %w",
+			res.Error,
+		)
+	}
+
+	// 2. Deliveries belonging to an expired event.
+	del := db.Unscoped().
+		Where("event_id IN (?)", expiredEventIDs()).
+		Delete(&Delivery{})
+	if del.Error != nil {
+		return 0, fmt.Errorf(
+			"deleting expired deliveries: %w",
+			del.Error,
+		)
+	}
+
+	// 3. The expired events themselves.
+	ev := db.Unscoped().
+		Where("created_at < ?", cutoff).
+		Delete(&Event{})
+	if ev.Error != nil {
+		return 0, fmt.Errorf(
+			"deleting expired events: %w",
+			ev.Error,
+		)
+	}
+
+	return ev.RowsAffected, nil
+}

internal/database/retention_test.go

@@ -0,0 +1,277 @@
+package database_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/fx/fxtest"
+	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
+	"sneak.berlin/go/webhooker/internal/config"
+	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/globals"
+	"sneak.berlin/go/webhooker/internal/logger"
+)
+
+// retentionTestEnv bundles the pieces a retention test drives.
+type retentionTestEnv struct {
+	reaper *database.RetentionReaper
+	mainDB *database.Database
+	mgr    *database.WebhookDBManager
+}
+
+func setupRetentionTest(t *testing.T) *retentionTestEnv {
+	t.Helper()
+
+	lc := fxtest.NewLifecycle(t)
+
+	g := &globals.Globals{
+		Appname: "webhooker-test",
+		Version: "test",
+	}
+
+	l, err := logger.New(lc, logger.LoggerParams{Globals: g})
+	require.NoError(t, err)
+
+	cfg := &config.Config{
+		DataDir:     t.TempDir(),
+		Environment: "dev",
+	}
+
+	mainDB, err := database.New(lc, database.DatabaseParams{
+		Config: cfg,
+		Logger: l,
+	})
+	require.NoError(t, err)
+
+	mgr, err := database.NewWebhookDBManager(
+		lc,
+		database.WebhookDBManagerParams{Config: cfg, Logger: l},
+	)
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	require.NoError(t, lc.Start(ctx))
+	t.Cleanup(func() { require.NoError(t, lc.Stop(ctx)) })
+
+	return &retentionTestEnv{
+		reaper: database.NewTestRetentionReaper(mainDB, mgr),
+		mainDB: mainDB,
+		mgr:    mgr,
+	}
+}
+
+// createWebhook inserts a webhook row into the main database with the
+// given retention policy and returns its ID.
+func createWebhook(
+	t *testing.T,
+	db *gorm.DB,
+	retentionDays int,
+) string {
+	t.Helper()
+
+	wh := &database.Webhook{
+		UserID:        uuid.New().String(),
+		Name:          "test-webhook",
+		RetentionDays: retentionDays,
+	}
+	require.NoError(
+		t,
+		db.Omit(clause.Associations).Create(wh).Error,
+	)
+
+	// The RetentionDays column carries a GORM default of 30, so a
+	// zero (or negative) value passed to Create is replaced by that
+	// default. Force the requested value explicitly so the
+	// retain-forever (<= 0) path can be exercised.
+	require.NoError(
+		t,
+		db.Model(wh).
+			Update("retention_days", retentionDays).Error,
+	)
+
+	return wh.ID
+}
+
+// eventChain is the set of row IDs seeded for a single event.
+type eventChain struct {
+	eventID    string
+	deliveryID string
+	resultID   string
+}
+
+// seedEventChain creates an event with one delivery and one delivery
+// result, all stamped with createdAt, and returns their IDs.
+func seedEventChain(
+	t *testing.T,
+	db *gorm.DB,
+	webhookID string,
+	createdAt time.Time,
+) eventChain {
+	t.Helper()
+
+	event := &database.Event{
+		WebhookID:    webhookID,
+		EntrypointID: uuid.New().String(),
+		Method:       "POST",
+		Body:         `{"seed": true}`,
+		ContentType:  "application/json",
+	}
+	event.CreatedAt = createdAt
+	require.NoError(t, db.Create(event).Error)
+
+	delivery := &database.Delivery{
+		EventID:  event.ID,
+		TargetID: uuid.New().String(),
+		Status:   database.DeliveryStatusDelivered,
+	}
+	delivery.CreatedAt = createdAt
+	require.NoError(t, db.Create(delivery).Error)
+
+	result := &database.DeliveryResult{
+		DeliveryID: delivery.ID,
+		AttemptNum: 1,
+		Success:    true,
+		StatusCode: 200,
+		Duration:   10,
+	}
+	result.CreatedAt = createdAt
+	require.NoError(t, db.Create(result).Error)
+
+	return eventChain{
+		eventID:    event.ID,
+		deliveryID: delivery.ID,
+		resultID:   result.ID,
+	}
+}
+
+// countByID returns how many rows of model match the given id,
+// counting even hard-deletable rows via Unscoped.
+func countByID(
+	t *testing.T,
+	db *gorm.DB,
+	model any,
+	id string,
+) int64 {
+	t.Helper()
+
+	var n int64
+
+	require.NoError(
+		t,
+		db.Unscoped().Model(model).
+			Where("id = ?", id).Count(&n).Error,
+	)
+
+	return n
+}
+
+func assertChainGone(
+	t *testing.T,
+	db *gorm.DB,
+	chain eventChain,
+) {
+	t.Helper()
+
+	assert.Zero(
+		t,
+		countByID(t, db, &database.Event{}, chain.eventID),
+		"expired event should be removed",
+	)
+	assert.Zero(
+		t,
+		countByID(t, db, &database.Delivery{}, chain.deliveryID),
+		"expired delivery should be removed",
+	)
+	assert.Zero(
+		t,
+		countByID(
+			t, db, &database.DeliveryResult{}, chain.resultID,
+		),
+		"expired delivery result should be removed",
+	)
+}
+
+func assertChainPresent(
+	t *testing.T,
+	db *gorm.DB,
+	chain eventChain,
+) {
+	t.Helper()
+
+	assert.Equal(
+		t,
+		int64(1),
+		countByID(t, db, &database.Event{}, chain.eventID),
+		"recent event should be retained",
+	)
+	assert.Equal(
+		t,
+		int64(1),
+		countByID(t, db, &database.Delivery{}, chain.deliveryID),
+		"recent delivery should be retained",
+	)
+	assert.Equal(
+		t,
+		int64(1),
+		countByID(
+			t, db, &database.DeliveryResult{}, chain.resultID,
+		),
+		"recent delivery result should be retained",
+	)
+}
+
+func TestRetentionReaper_ReapsExpiredKeepsRecent(t *testing.T) {
+	t.Parallel()
+
+	env := setupRetentionTest(t)
+
+	const retentionDays = 30
+
+	webhookID := createWebhook(
+		t, env.mainDB.DB(), retentionDays,
+	)
+
+	db, err := env.mgr.GetDB(webhookID)
+	require.NoError(t, err)
+
+	now := time.Now()
+	old := seedEventChain(
+		t, db, webhookID,
+		now.Add(-40*24*time.Hour),
+	)
+	recent := seedEventChain(
+		t, db, webhookID,
+		now.Add(-1*24*time.Hour),
+	)
+
+	env.reaper.ExportSweep(context.Background())
+
+	assertChainGone(t, db, old)
+	assertChainPresent(t, db, recent)
+}
+
+func TestRetentionReaper_RetainsForeverWhenNonPositive(t *testing.T) {
+	t.Parallel()
+
+	env := setupRetentionTest(t)
+
+	// RetentionDays of zero means retain forever.
+	webhookID := createWebhook(t, env.mainDB.DB(), 0)
+
+	db, err := env.mgr.GetDB(webhookID)
+	require.NoError(t, err)
+
+	ancient := seedEventChain(
+		t, db, webhookID,
+		time.Now().Add(-365*24*time.Hour),
+	)
+
+	env.reaper.ExportSweep(context.Background())
+
+	assertChainPresent(t, db, ancient)
+}

internal/delivery/engine_test.go

@@ -1,6 +1,7 @@
 package delivery_test
 
 import (
+	"bytes"
 	"context"
 	"database/sql"
 	"encoding/json"
@@ -1652,6 +1653,179 @@ func TestProcessDelivery_RoutesToSlack(t *testing.T) {
 	)
 }
 
+// newLogCaptureEngine builds a test engine whose logger
+// writes to the returned buffer, for inspecting log output.
+func newLogCaptureEngine(
+	t *testing.T,
+) (*delivery.Engine, *bytes.Buffer) {
+	t.Helper()
+
+	var buf bytes.Buffer
+
+	log := slog.New(slog.NewTextHandler(
+		&buf,
+		&slog.HandlerOptions{Level: slog.LevelDebug},
+	))
+
+	e := delivery.NewTestEngine(
+		log, &http.Client{Timeout: 5 * time.Second}, 1,
+	)
+
+	return e, &buf
+}
+
+// assertLogLineComplete asserts the captured log output
+// carries the full inbound webhook content and ids.
+func assertLogLineComplete(
+	t *testing.T, out string, event database.Event,
+) {
+	t.Helper()
+
+	assert.Contains(t, out, "log-body-marker",
+		"log line must contain the full request body",
+	)
+
+	assert.Contains(t, out, "Content-Type",
+		"log line must contain the full request headers",
+	)
+
+	assert.Contains(t, out, event.EntrypointID,
+		"log line must contain the entrypoint id",
+	)
+
+	assert.Contains(t, out, event.WebhookID,
+		"log line must contain the webhook id",
+	)
+
+	assert.Contains(t, out, "application/json",
+		"log line must contain the content type",
+	)
+}
+
+func TestDeliverLog_LogsFullContent(t *testing.T) {
+	t.Parallel()
+
+	db := testWebhookDB(t)
+	e, buf := newLogCaptureEngine(t)
+
+	event := seedEvent(
+		t, db, `{"log-body-marker":"abc123"}`,
+	)
+
+	dlv := seedDelivery(
+		t, db, event.ID, uuid.New().String(),
+		database.DeliveryStatusPending,
+	)
+
+	d := &database.Delivery{
+		EventID:  event.ID,
+		TargetID: dlv.TargetID,
+		Status:   database.DeliveryStatusPending,
+		Event:    event,
+		Target: database.Target{
+			Name: "test-log-full",
+			Type: database.TargetTypeLog,
+		},
+	}
+	d.ID = dlv.ID
+
+	e.ExportDeliverLog(db, d)
+
+	assertLogLineComplete(t, buf.String(), event)
+
+	assertDeliveryStatus(t, db, dlv.ID,
+		database.DeliveryStatusDelivered,
+	)
+}
+
+// buildSlackRetryDelivery builds a Slack delivery whose
+// target is configured with retries enabled.
+func buildSlackRetryDelivery(
+	dlv database.Delivery,
+	event database.Event,
+	targetID, cfg string,
+) *database.Delivery {
+	d := &database.Delivery{
+		EventID:  event.ID,
+		TargetID: targetID,
+		Status:   database.DeliveryStatusPending,
+		Event:    event,
+		Target: database.Target{
+			Name:       "test-slack-retry",
+			Type:       database.TargetTypeSlack,
+			Config:     cfg,
+			MaxRetries: 5,
+		},
+	}
+	d.ID = dlv.ID
+
+	return d
+}
+
+func TestDeliverSlack_WithRetries_SchedulesRetry(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	db := testWebhookDB(t)
+	ts := newStatusServer(t, http.StatusServiceUnavailable)
+	e := testEngine(t, 1)
+	targetID := uuid.New().String()
+
+	slackCfg, err := json.Marshal(
+		delivery.SlackTargetConfig{WebhookURL: ts.URL},
+	)
+	require.NoError(t, err)
+
+	event := seedEvent(t, db, `{"slack":"retry"}`)
+
+	dlv := seedDelivery(
+		t, db, event.ID, targetID,
+		database.DeliveryStatusPending,
+	)
+
+	d := buildSlackRetryDelivery(
+		dlv, event, targetID, string(slackCfg),
+	)
+
+	task := &delivery.Task{
+		DeliveryID: dlv.ID,
+		TargetID:   targetID,
+		TargetType: database.TargetTypeSlack,
+		MaxRetries: 5,
+		AttemptNum: 1,
+	}
+
+	e.ExportProcessDelivery(context.TODO(), db, d, task)
+
+	assertDeliveryStatus(t, db, dlv.ID,
+		database.DeliveryStatusRetrying,
+	)
+
+	assertDeliveryResult(
+		t, db, dlv.ID, false,
+		http.StatusServiceUnavailable,
+	)
+}
+
+// newStatusServer starts a test server that always responds
+// with the given status code.
+func newStatusServer(
+	t *testing.T, code int,
+) *httptest.Server {
+	t.Helper()
+
+	ts := httptest.NewServer(http.HandlerFunc(
+		func(w http.ResponseWriter, _ *http.Request) {
+			w.WriteHeader(code)
+		},
+	))
+
+	t.Cleanup(ts.Close)
+
+	return ts
+}
+
 // readAll is a small helper to avoid importing io in
 // a test handler inline.
 func readAll(r interface {

internal/delivery/export_test.go

@@ -39,37 +39,50 @@ func ExportTruncate(s string, maxLen int) string {
 	return truncate(s, maxLen)
 }
 
-// ExportDeliverHTTP exposes deliverHTTP for testing.
+// ExportDeliverHTTP delivers via the http target for testing.
 func (e *Engine) ExportDeliverHTTP(
 	ctx context.Context,
 	webhookDB *gorm.DB,
 	d *database.Delivery,
 	task *Task,
 ) {
-	e.deliverHTTP(ctx, webhookDB, d, task)
+	e.httpTarget.Deliver(ctx, webhookDB, d, task, e)
 }
 
-// ExportDeliverDatabase exposes deliverDatabase.
+// ExportDeliverDatabase delivers via the database target.
 func (e *Engine) ExportDeliverDatabase(
 	webhookDB *gorm.DB, d *database.Delivery,
 ) {
-	e.deliverDatabase(webhookDB, d)
+	e.targets[database.TargetTypeDatabase].Deliver(
+		context.Background(), webhookDB, d, &Task{}, e,
+	)
 }
 
-// ExportDeliverLog exposes deliverLog for testing.
+// ExportDeliverLog delivers via the log target for testing.
 func (e *Engine) ExportDeliverLog(
 	webhookDB *gorm.DB, d *database.Delivery,
 ) {
-	e.deliverLog(webhookDB, d)
+	e.targets[database.TargetTypeLog].Deliver(
+		context.Background(), webhookDB, d, &Task{}, e,
+	)
 }
 
-// ExportDeliverSlack exposes deliverSlack for testing.
+// ExportDeliverSlack delivers via the slack target for
+// testing.
 func (e *Engine) ExportDeliverSlack(
 	ctx context.Context,
 	webhookDB *gorm.DB,
 	d *database.Delivery,
 ) {
-	e.deliverSlack(ctx, webhookDB, d)
+	task := &Task{
+		DeliveryID: d.ID,
+		TargetID:   d.TargetID,
+		AttemptNum: 1,
+	}
+
+	e.targets[database.TargetTypeSlack].Deliver(
+		ctx, webhookDB, d, task, e,
+	)
 }
 
 // ExportProcessNewTask exposes processNewTask.
@@ -96,53 +109,56 @@ func (e *Engine) ExportProcessDelivery(
 	e.processDelivery(ctx, webhookDB, d, task)
 }
 
-// ExportGetCircuitBreaker exposes getCircuitBreaker.
+// ExportGetCircuitBreaker exposes the http target's
+// getCircuitBreaker.
 func (e *Engine) ExportGetCircuitBreaker(
 	targetID string,
 ) *CircuitBreaker {
-	return e.getCircuitBreaker(targetID)
+	return e.httpTarget.getCircuitBreaker(targetID)
 }
 
 // ExportParseHTTPConfig exposes parseHTTPConfig.
 func (e *Engine) ExportParseHTTPConfig(
 	configJSON string,
 ) (*HTTPTargetConfig, error) {
-	return e.parseHTTPConfig(configJSON)
+	return parseHTTPConfig(configJSON)
 }
 
 // ExportParseSlackConfig exposes parseSlackConfig.
 func (e *Engine) ExportParseSlackConfig(
 	configJSON string,
 ) (*SlackTargetConfig, error) {
-	return e.parseSlackConfig(configJSON)
+	return parseSlackConfig(configJSON)
 }
 
-// ExportDoHTTPRequest exposes doHTTPRequest.
+// ExportDoHTTPRequest exposes the http target's
+// doHTTPRequest.
 func (e *Engine) ExportDoHTTPRequest(
 	ctx context.Context,
 	cfg *HTTPTargetConfig,
 	event *database.Event,
 ) (int, string, int64, error) {
-	return e.doHTTPRequest(ctx, cfg, event)
+	return e.httpTarget.doHTTPRequest(ctx, cfg, event)
 }
 
-// ExportClientForConfig exposes clientForConfig.
+// ExportClientForConfig exposes the http target's
+// clientForConfig.
 func (e *Engine) ExportClientForConfig(
 	cfg *HTTPTargetConfig,
 ) *http.Client {
-	return e.clientForConfig(cfg)
+	return e.httpTarget.clientForConfig(cfg)
 }
 
-// ExportClient returns the engine's shared HTTP client.
+// ExportClient returns the http target's shared HTTP client.
 func (e *Engine) ExportClient() *http.Client {
-	return e.client
+	return e.httpTarget.client
 }
 
-// ExportScheduleRetry exposes scheduleRetry.
+// ExportScheduleRetry exposes ScheduleRetry.
 func (e *Engine) ExportScheduleRetry(
 	task Task, delay time.Duration,
 ) {
-	e.scheduleRetry(task, delay)
+	e.ScheduleRetry(task, delay)
 }
 
 // ExportRecoverPendingDeliveries exposes
@@ -199,13 +215,15 @@ func NewTestEngine(
 	client *http.Client,
 	workers int,
 ) *Engine {
-	return &Engine{
+	e := &Engine{
 		log:        log,
-		client:     client,
 		deliveryCh: make(chan Task, deliveryChannelSize),
 		retryCh:    make(chan Task, retryChannelSize),
 		workers:    workers,
 	}
+	e.initTargets(client)
+
+	return e
 }
 
 // NewTestEngineSmallRetry creates an Engine with a tiny
@@ -213,10 +231,13 @@ func NewTestEngine(
 func NewTestEngineSmallRetry(
 	log *slog.Logger,
 ) *Engine {
-	return &Engine{
+	e := &Engine{
 		log:     log,
 		retryCh: make(chan Task, 1),
 	}
+	e.initTargets(nil)
+
+	return e
 }
 
 // NewTestEngineWithDB creates an Engine with a real
@@ -228,15 +249,17 @@ func NewTestEngineWithDB(
 	client *http.Client,
 	workers int,
 ) *Engine {
-	return &Engine{
+	e := &Engine{
 		database:   db,
 		dbManager:  dbMgr,
 		log:        log,
-		client:     client,
 		deliveryCh: make(chan Task, deliveryChannelSize),
 		retryCh:    make(chan Task, retryChannelSize),
 		workers:    workers,
 	}
+	e.initTargets(client)
+
+	return e
 }
 
 // NewTestCircuitBreaker creates a CircuitBreaker with

internal/delivery/target.go

@@ -0,0 +1,101 @@
+package delivery
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"gorm.io/gorm"
+	"sneak.berlin/go/webhooker/internal/database"
+)
+
+// Scheduler re-enqueues a task for a future delivery attempt.
+// The engine provides one to each target so a target can own
+// its retries durably: it records the attempt, marks the
+// delivery retrying, and asks the Scheduler to deliver the
+// next attempt after delay — exactly what the engine does for
+// its own restart recovery.
+type Scheduler interface {
+	ScheduleRetry(task Task, delay time.Duration)
+}
+
+// Target delivers an event to one target type. Each type is
+// an implementation. A Target owns its whole delivery: it
+// makes the attempt, records the DeliveryResult and updates
+// the DeliveryStatus, and — for targets that retry — decides
+// whether to retry, computes its own backoff, gates with its
+// own circuit breaker, and reschedules via the injected
+// Scheduler. Fire-and-forget targets simply record a single
+// attempt.
+type Target interface {
+	Deliver(
+		ctx context.Context,
+		webhookDB *gorm.DB,
+		d *database.Delivery,
+		task *Task,
+		sched Scheduler,
+	)
+}
+
+// rescheduler is implemented by targets that own durable
+// retries. The engine's restart recovery and periodic sweep
+// use it to let the target recompute the schedule for an
+// orphaned retrying delivery, keeping the retry schedule
+// target-owned. Fire-and-forget targets do not implement it
+// and their (never-occurring) retrying deliveries are
+// skipped.
+type rescheduler interface {
+	// remainingBackoff returns how long to wait before the
+	// next attempt of a recovered retrying delivery.
+	remainingBackoff(
+		webhookDB *gorm.DB,
+		deliveryID string,
+		attemptNum int,
+	) time.Duration
+
+	// backoffElapsed reports whether the backoff window for
+	// the last attempt has already passed, so the periodic
+	// sweep can re-enqueue the delivery now.
+	backoffElapsed(
+		webhookDB *gorm.DB,
+		deliveryID string,
+		attemptNum int,
+	) bool
+}
+
+// attemptResult is the outcome of a single delivery attempt,
+// as reported by a target's per-attempt function to the
+// shared retry core.
+type attemptResult struct {
+	statusCode int
+	respBody   string
+	duration   int64
+	success    bool
+	errMsg     string
+}
+
+// initTargets builds the target registry, wiring each target
+// to the engine's persistence helpers and giving the HTTP and
+// Slack targets the shared SSRF-safe client. It is called by
+// both New and the test constructors so the registry is
+// always populated.
+func (e *Engine) initTargets(client *http.Client) {
+	httpT := &httpTarget{
+		httpCore: &httpCore{eng: e},
+		client:   client,
+	}
+
+	slackT := &slackTarget{
+		httpCore: &httpCore{eng: e},
+		client:   client,
+	}
+
+	e.httpTarget = httpT
+
+	e.targets = map[database.TargetType]Target{
+		database.TargetTypeHTTP:     httpT,
+		database.TargetTypeSlack:    slackT,
+		database.TargetTypeDatabase: &databaseTarget{eng: e},
+		database.TargetTypeLog:      &logTarget{eng: e},
+	}
+}

internal/delivery/target_database.go

@@ -0,0 +1,34 @@
+package delivery
+
+import (
+	"context"
+
+	"gorm.io/gorm"
+	"sneak.berlin/go/webhooker/internal/database"
+)
+
+// databaseTarget is a fire-and-forget target: the event is
+// already persisted in the per-webhook database by the time
+// delivery runs, so the target records a single successful
+// attempt. (Durable archiving to a separate store is tracked
+// as its own work.)
+type databaseTarget struct {
+	eng *Engine
+}
+
+// Deliver implements Target.
+func (t *databaseTarget) Deliver(
+	_ context.Context,
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	_ *Task,
+	_ Scheduler,
+) {
+	t.eng.recordResult(
+		webhookDB, d, 1, true, 0, "", "", 0,
+	)
+
+	t.eng.updateDeliveryStatus(
+		webhookDB, d, database.DeliveryStatusDelivered,
+	)
+}

internal/delivery/target_http.go

@@ -0,0 +1,499 @@
+package delivery
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+	"time"
+
+	"gorm.io/gorm"
+	"sneak.berlin/go/webhooker/internal/database"
+)
+
+// Sentinel errors returned by the config parsers.
+var (
+	errEmptyTargetConfig = errors.New(
+		"empty target config",
+	)
+	errMissingTargetURL = errors.New(
+		"target URL is required",
+	)
+)
+
+// HTTPTargetConfig holds configuration for http target
+// types.
+type HTTPTargetConfig struct {
+	URL     string            `json:"url"`
+	Headers map[string]string `json:"headers,omitempty"`
+	Timeout int               `json:"timeout,omitempty"`
+}
+
+// httpCore holds the retry, backoff, and circuit-breaker
+// machinery shared by the HTTP and Slack targets. Each of
+// those targets owns its own httpCore instance (and thus its
+// own circuit breakers); the per-attempt request differs
+// between them and is supplied as a closure.
+type httpCore struct {
+	eng *Engine
+
+	// circuitBreakers stores a *CircuitBreaker per target ID.
+	circuitBreakers sync.Map
+}
+
+// deliver runs one delivery attempt through the retry core.
+// A maxRetries of 0 is fire-and-forget: a single attempt is
+// recorded and no circuit breaker is consulted. A positive
+// maxRetries gates the attempt on the circuit breaker and
+// schedules a backed-off retry on failure.
+func (c *httpCore) deliver(
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	task *Task,
+	sched Scheduler,
+	maxRetries int,
+	attempt func() attemptResult,
+) {
+	if maxRetries == 0 {
+		c.fireAndForget(webhookDB, d, attempt())
+
+		return
+	}
+
+	c.withRetry(
+		webhookDB, d, task, sched, maxRetries, attempt,
+	)
+}
+
+func (c *httpCore) fireAndForget(
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	res attemptResult,
+) {
+	c.eng.recordResult(
+		webhookDB, d, 1, res.success,
+		res.statusCode, res.respBody, res.errMsg,
+		res.duration,
+	)
+
+	if res.success {
+		c.eng.updateDeliveryStatus(
+			webhookDB, d,
+			database.DeliveryStatusDelivered,
+		)
+
+		return
+	}
+
+	c.eng.updateDeliveryStatus(
+		webhookDB, d, database.DeliveryStatusFailed,
+	)
+}
+
+func (c *httpCore) withRetry(
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	task *Task,
+	sched Scheduler,
+	maxRetries int,
+	attempt func() attemptResult,
+) {
+	cb := c.getCircuitBreaker(task.TargetID)
+	if c.circuitBreakerBlock(webhookDB, d, task, sched, cb) {
+		return
+	}
+
+	attemptNum := task.AttemptNum
+
+	res := attempt()
+
+	c.eng.recordResult(
+		webhookDB, d, attemptNum, res.success,
+		res.statusCode, res.respBody, res.errMsg,
+		res.duration,
+	)
+
+	if res.success {
+		cb.RecordSuccess()
+
+		c.eng.updateDeliveryStatus(
+			webhookDB, d,
+			database.DeliveryStatusDelivered,
+		)
+
+		return
+	}
+
+	cb.RecordFailure()
+
+	c.handleRetry(
+		webhookDB, d, task, sched, maxRetries, attemptNum,
+	)
+}
+
+func (c *httpCore) circuitBreakerBlock(
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	task *Task,
+	sched Scheduler,
+	cb *CircuitBreaker,
+) bool {
+	if cb.Allow() {
+		return false
+	}
+
+	remaining := cb.CooldownRemaining()
+
+	c.eng.log.Info(
+		"circuit breaker open, skipping delivery",
+		"target_id", task.TargetID,
+		"target_name", task.TargetName,
+		"delivery_id", d.ID,
+		"cooldown_remaining", remaining,
+	)
+
+	c.eng.updateDeliveryStatus(
+		webhookDB, d,
+		database.DeliveryStatusRetrying,
+	)
+
+	retryTask := *task
+	sched.ScheduleRetry(retryTask, remaining)
+
+	return true
+}
+
+func (c *httpCore) handleRetry(
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	task *Task,
+	sched Scheduler,
+	maxRetries int,
+	attemptNum int,
+) {
+	if attemptNum >= maxRetries {
+		c.eng.updateDeliveryStatus(
+			webhookDB, d,
+			database.DeliveryStatusFailed,
+		)
+
+		return
+	}
+
+	c.eng.updateDeliveryStatus(
+		webhookDB, d, database.DeliveryStatusRetrying,
+	)
+
+	backoff := calcBackoff(attemptNum)
+
+	retryTask := *task
+	retryTask.AttemptNum = attemptNum + 1
+	sched.ScheduleRetry(retryTask, backoff)
+}
+
+func (c *httpCore) getCircuitBreaker(
+	targetID string,
+) *CircuitBreaker {
+	if val, ok := c.circuitBreakers.Load(targetID); ok {
+		cb, _ := val.(*CircuitBreaker)
+
+		return cb
+	}
+
+	fresh := NewCircuitBreaker()
+
+	actual, _ := c.circuitBreakers.LoadOrStore(
+		targetID, fresh,
+	)
+
+	cb, _ := actual.(*CircuitBreaker)
+
+	return cb
+}
+
+// remainingBackoff returns how long remains of the backoff
+// window for the last attempt of a recovered retrying
+// delivery. It implements rescheduler.
+func (c *httpCore) remainingBackoff(
+	webhookDB *gorm.DB,
+	deliveryID string,
+	attemptNum int,
+) time.Duration {
+	var lastResult database.DeliveryResult
+
+	err := webhookDB.
+		Where("delivery_id = ?", deliveryID).
+		Order("created_at DESC").
+		First(&lastResult).Error
+	if err != nil {
+		return 0
+	}
+
+	backoff := calcBackoff(attemptNum)
+	elapsed := time.Since(lastResult.CreatedAt)
+	remaining := backoff - elapsed
+
+	return max(remaining, 0)
+}
+
+// backoffElapsed reports whether the backoff window for the
+// last attempt of a retrying delivery has passed. It
+// implements rescheduler.
+func (c *httpCore) backoffElapsed(
+	webhookDB *gorm.DB,
+	deliveryID string,
+	attemptNum int,
+) bool {
+	var lastResult database.DeliveryResult
+
+	err := webhookDB.
+		Where("delivery_id = ?", deliveryID).
+		Order("created_at DESC").
+		First(&lastResult).Error
+	if err != nil {
+		return true
+	}
+
+	backoff := calcBackoff(attemptNum)
+
+	return time.Since(lastResult.CreatedAt) >= backoff
+}
+
+func calcBackoff(attemptNum int) time.Duration {
+	shift := max(attemptNum-1, 0)
+	shift = min(shift, maxBackoffShift)
+
+	return time.Duration(1<<uint(shift)) * time.Second
+}
+
+// httpTarget delivers events to http targets. It forwards the
+// event body and (filtered) request headers to the configured
+// URL and owns retry, backoff, and circuit breaking through
+// the shared httpCore.
+type httpTarget struct {
+	*httpCore
+
+	client *http.Client
+}
+
+// Deliver implements Target.
+func (t *httpTarget) Deliver(
+	ctx context.Context,
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	task *Task,
+	sched Scheduler,
+) {
+	cfg, err := parseHTTPConfig(d.Target.Config)
+	if err != nil {
+		t.eng.log.Error(
+			"invalid HTTP target config",
+			"target_id", d.TargetID,
+			"error", err,
+		)
+
+		t.eng.recordResult(
+			webhookDB, d, task.AttemptNum,
+			false, 0, "", err.Error(), 0,
+		)
+
+		t.eng.updateDeliveryStatus(
+			webhookDB, d, database.DeliveryStatusFailed,
+		)
+
+		return
+	}
+
+	attempt := func() attemptResult {
+		return t.attempt(ctx, cfg, &d.Event)
+	}
+
+	t.deliver(
+		webhookDB, d, task, sched,
+		d.Target.MaxRetries, attempt,
+	)
+}
+
+// attempt performs a single HTTP delivery attempt and derives
+// the success flag and error message the same way the engine
+// did: a non-2xx response is a failure but carries no error
+// string; only a transport-level error does.
+func (t *httpTarget) attempt(
+	ctx context.Context,
+	cfg *HTTPTargetConfig,
+	event *database.Event,
+) attemptResult {
+	statusCode, respBody, duration, reqErr :=
+		t.doHTTPRequest(ctx, cfg, event)
+
+	success := reqErr == nil &&
+		statusCode >= httpSuccessMin &&
+		statusCode < httpSuccessMax
+
+	errMsg := ""
+	if reqErr != nil {
+		errMsg = reqErr.Error()
+	}
+
+	return attemptResult{
+		statusCode: statusCode,
+		respBody:   respBody,
+		duration:   duration,
+		success:    success,
+		errMsg:     errMsg,
+	}
+}
+
+func (t *httpTarget) doHTTPRequest(
+	ctx context.Context,
+	cfg *HTTPTargetConfig,
+	event *database.Event,
+) (int, string, int64, error) {
+	start := time.Now()
+
+	req, reqErr := http.NewRequestWithContext(
+		ctx,
+		http.MethodPost,
+		cfg.URL,
+		bytes.NewReader([]byte(event.Body)),
+	)
+	if reqErr != nil {
+		return 0, "", 0, fmt.Errorf(
+			"creating request: %w", reqErr,
+		)
+	}
+
+	applyRequestHeaders(req, event, cfg)
+
+	client := t.clientForConfig(cfg)
+
+	resp, doErr := executeHTTPRequest(client, req)
+
+	dur := time.Since(start).Milliseconds()
+	if doErr != nil {
+		return 0, "", dur, fmt.Errorf(
+			"sending request: %w", doErr,
+		)
+	}
+
+	defer func() { _ = resp.Body.Close() }()
+
+	body, readErr := io.ReadAll(
+		io.LimitReader(resp.Body, maxBodyLog),
+	)
+	if readErr != nil {
+		return resp.StatusCode, "", dur,
+			fmt.Errorf(
+				"reading response body: %w", readErr,
+			)
+	}
+
+	return resp.StatusCode, string(body), dur, nil
+}
+
+func (t *httpTarget) clientForConfig(
+	cfg *HTTPTargetConfig,
+) *http.Client {
+	if cfg.Timeout > 0 {
+		// Reuse the shared client's SSRF-safe transport so
+		// a per-target timeout does not drop the
+		// request-time private-IP guard. Only the timeout
+		// is overridden.
+		return &http.Client{
+			Timeout: time.Duration(
+				cfg.Timeout,
+			) * time.Second,
+			Transport: t.client.Transport,
+		}
+	}
+
+	return t.client
+}
+
+func parseHTTPConfig(
+	configJSON string,
+) (*HTTPTargetConfig, error) {
+	if configJSON == "" {
+		return nil, errEmptyTargetConfig
+	}
+
+	var cfg HTTPTargetConfig
+
+	err := json.Unmarshal(
+		[]byte(configJSON), &cfg,
+	)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"parsing config JSON: %w", err,
+		)
+	}
+
+	if cfg.URL == "" {
+		return nil, errMissingTargetURL
+	}
+
+	return &cfg, nil
+}
+
+// isForwardableHeader returns true if the header should
+// be forwarded to targets.
+func isForwardableHeader(name string) bool {
+	switch http.CanonicalHeaderKey(name) {
+	case "Host", "Connection", "Keep-Alive",
+		"Transfer-Encoding", "Te", "Trailer",
+		"Upgrade", "Proxy-Authorization",
+		"Proxy-Connection", "Content-Length":
+		return false
+	default:
+		return true
+	}
+}
+
+func applyRequestHeaders(
+	req *http.Request,
+	event *database.Event,
+	cfg *HTTPTargetConfig,
+) {
+	if event.ContentType != "" {
+		req.Header.Set(
+			"Content-Type", event.ContentType,
+		)
+	}
+
+	var originalHeaders map[string][]string
+
+	if event.Headers != "" {
+		jsonErr := json.Unmarshal(
+			[]byte(event.Headers),
+			&originalHeaders,
+		)
+		if jsonErr == nil {
+			for k, vals := range originalHeaders {
+				if isForwardableHeader(k) {
+					for _, v := range vals {
+						req.Header.Add(k, v)
+					}
+				}
+			}
+		}
+	}
+
+	for k, v := range cfg.Headers {
+		req.Header.Set(k, v)
+	}
+
+	req.Header.Set("User-Agent", "webhooker/1.0")
+}
+
+// executeHTTPRequest sends an HTTP request using the provided
+// client. URLs are validated by the config parsers and the
+// SSRF-safe transport before reaching here.
+func executeHTTPRequest(
+	client *http.Client, req *http.Request,
+) (*http.Response, error) {
+	return client.Do(req) //#nosec G704 -- URL validated by parseHTTPConfig/parseSlackConfig and SSRF-safe transport
+}

internal/delivery/target_log.go

@@ -0,0 +1,47 @@
+package delivery
+
+import (
+	"context"
+
+	"gorm.io/gorm"
+	"sneak.berlin/go/webhooker/internal/database"
+)
+
+// logTarget is a fire-and-forget target that logs the entire
+// inbound webhook — the full request body and headers, plus
+// the method, content type, and the webhook and entrypoint
+// ids — then records a single successful attempt.
+type logTarget struct {
+	eng *Engine
+}
+
+// Deliver implements Target.
+func (t *logTarget) Deliver(
+	_ context.Context,
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	_ *Task,
+	_ Scheduler,
+) {
+	t.eng.log.Info(
+		"webhook event delivered to log target",
+		"delivery_id", d.ID,
+		"event_id", d.EventID,
+		"target_id", d.TargetID,
+		"target_name", d.Target.Name,
+		"webhook_id", d.Event.WebhookID,
+		"entrypoint_id", d.Event.EntrypointID,
+		"method", d.Event.Method,
+		"content_type", d.Event.ContentType,
+		"headers", d.Event.Headers,
+		"body", d.Event.Body,
+	)
+
+	t.eng.recordResult(
+		webhookDB, d, 1, true, 0, "", "", 0,
+	)
+
+	t.eng.updateDeliveryStatus(
+		webhookDB, d, database.DeliveryStatusDelivered,
+	)
+}

internal/delivery/target_slack.go

@@ -0,0 +1,299 @@
+package delivery
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"gorm.io/gorm"
+	"sneak.berlin/go/webhooker/internal/database"
+)
+
+// errMissingWebhookURL is returned when a Slack target config
+// omits its webhook URL.
+var errMissingWebhookURL = errors.New(
+	"webhook_url is required",
+)
+
+// SlackTargetConfig holds configuration for slack target
+// types.
+type SlackTargetConfig struct {
+	WebhookURL string `json:"webhookUrl"`
+}
+
+// slackTarget delivers events to Slack incoming webhooks. It
+// formats the event into a Slack message and posts it as
+// JSON. It shares the retry core with the HTTP target: a
+// MaxRetries of 0 stays single-attempt fire-and-forget
+// (preserving existing Slack targets), while a positive
+// MaxRetries adds backoff and circuit breaking.
+type slackTarget struct {
+	*httpCore
+
+	client *http.Client
+}
+
+// Deliver implements Target.
+func (t *slackTarget) Deliver(
+	ctx context.Context,
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	task *Task,
+	sched Scheduler,
+) {
+	cfg, err := parseSlackConfig(d.Target.Config)
+	if err != nil {
+		t.eng.log.Error(
+			"invalid Slack target config",
+			"target_id", d.TargetID,
+			"error", err,
+		)
+
+		t.failConfig(webhookDB, d, err)
+
+		return
+	}
+
+	msg := FormatSlackMessage(&d.Event)
+
+	payload, err := json.Marshal(
+		map[string]string{"text": msg},
+	)
+	if err != nil {
+		t.eng.log.Error(
+			"failed to marshal Slack payload",
+			"target_id", d.TargetID,
+			"error", err,
+		)
+
+		t.failConfig(webhookDB, d, err)
+
+		return
+	}
+
+	attempt := func() attemptResult {
+		return t.attempt(ctx, cfg, payload)
+	}
+
+	t.deliver(
+		webhookDB, d, task, sched,
+		d.Target.MaxRetries, attempt,
+	)
+}
+
+// failConfig records a first-attempt failure for a delivery
+// that could not be prepared (bad config or unmarshalable
+// payload) and marks it failed.
+func (t *slackTarget) failConfig(
+	webhookDB *gorm.DB,
+	d *database.Delivery,
+	err error,
+) {
+	t.eng.recordResult(
+		webhookDB, d, 1,
+		false, 0, "", err.Error(), 0,
+	)
+
+	t.eng.updateDeliveryStatus(
+		webhookDB, d, database.DeliveryStatusFailed,
+	)
+}
+
+// attempt performs a single Slack POST and derives its
+// outcome, preserving the engine's original semantics: a
+// non-2xx response records an "HTTP <code>" error string and
+// a transport error records a "sending request" error.
+func (t *slackTarget) attempt(
+	ctx context.Context,
+	cfg *SlackTargetConfig,
+	payload []byte,
+) attemptResult {
+	start := time.Now()
+
+	req, err := http.NewRequestWithContext(
+		ctx,
+		http.MethodPost,
+		cfg.WebhookURL,
+		bytes.NewReader(payload),
+	)
+	if err != nil {
+		return attemptResult{
+			success: false,
+			errMsg:  err.Error(),
+		}
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", "webhooker/1.0")
+
+	resp, doErr := executeHTTPRequest(t.client, req)
+	durationMs := time.Since(start).Milliseconds()
+
+	if doErr != nil {
+		return attemptResult{
+			success:  false,
+			duration: durationMs,
+			errMsg: fmt.Errorf(
+				"sending request: %w", doErr,
+			).Error(),
+		}
+	}
+
+	defer func() { _ = resp.Body.Close() }()
+
+	return t.readSlackResponse(resp, durationMs)
+}
+
+func (t *slackTarget) readSlackResponse(
+	resp *http.Response,
+	durationMs int64,
+) attemptResult {
+	body, readErr := io.ReadAll(
+		io.LimitReader(resp.Body, maxBodyLog),
+	)
+	if readErr != nil {
+		t.eng.log.Error(
+			"failed to read Slack response body",
+			"error", readErr,
+		)
+	}
+
+	success := resp.StatusCode >= httpSuccessMin &&
+		resp.StatusCode < httpSuccessMax
+
+	errMsg := ""
+	if !success {
+		errMsg = fmt.Sprintf("HTTP %d", resp.StatusCode)
+	}
+
+	return attemptResult{
+		statusCode: resp.StatusCode,
+		respBody:   string(body),
+		duration:   durationMs,
+		success:    success,
+		errMsg:     errMsg,
+	}
+}
+
+func parseSlackConfig(
+	configJSON string,
+) (*SlackTargetConfig, error) {
+	if configJSON == "" {
+		return nil, errEmptyTargetConfig
+	}
+
+	var cfg SlackTargetConfig
+
+	err := json.Unmarshal(
+		[]byte(configJSON), &cfg,
+	)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"parsing config JSON: %w", err,
+		)
+	}
+
+	if cfg.WebhookURL == "" {
+		return nil, errMissingWebhookURL
+	}
+
+	return &cfg, nil
+}
+
+// FormatSlackMessage builds a Slack-compatible message
+// string from a webhook event.
+func FormatSlackMessage(
+	event *database.Event,
+) string {
+	var b strings.Builder
+
+	b.WriteString("*Webhook Event Received*\n")
+
+	fmt.Fprintf(
+		&b, "*Method:* `%s`\n", event.Method,
+	)
+
+	fmt.Fprintf(
+		&b,
+		"*Content-Type:* `%s`\n",
+		event.ContentType,
+	)
+
+	fmt.Fprintf(
+		&b,
+		"*Timestamp:* `%s`\n",
+		event.CreatedAt.UTC().Format(time.RFC3339),
+	)
+
+	fmt.Fprintf(
+		&b,
+		"*Body Size:* %d bytes\n",
+		len(event.Body),
+	)
+
+	if event.Body == "" {
+		b.WriteString("\n_(empty body)_\n")
+
+		return b.String()
+	}
+
+	if formatted := formatJSONBody(event.Body); formatted != "" {
+		b.WriteString(formatted)
+
+		return b.String()
+	}
+
+	formatRawBody(&b, event.Body)
+
+	return b.String()
+}
+
+func formatJSONBody(body string) string {
+	var parsed json.RawMessage
+	if json.Unmarshal([]byte(body), &parsed) != nil {
+		return ""
+	}
+
+	var pretty bytes.Buffer
+	if json.Indent(&pretty, parsed, "", "  ") != nil {
+		return ""
+	}
+
+	var b strings.Builder
+
+	b.WriteString("\n```\n")
+
+	prettyStr := pretty.String()
+
+	const maxPayloadDisplay = 3500
+	if len(prettyStr) > maxPayloadDisplay {
+		b.WriteString(prettyStr[:maxPayloadDisplay])
+		b.WriteString("\n... (truncated)")
+	} else {
+		b.WriteString(prettyStr)
+	}
+
+	b.WriteString("\n```\n")
+
+	return b.String()
+}
+
+func formatRawBody(b *strings.Builder, body string) {
+	b.WriteString("\n```\n")
+
+	const maxRawDisplay = 3500
+	if len(body) > maxRawDisplay {
+		b.WriteString(body[:maxRawDisplay])
+		b.WriteString("\n... (truncated)")
+	} else {
+		b.WriteString(body)
+	}
+
+	b.WriteString("\n```\n")
+}

internal/handlers/webhook.go

@@ -329,6 +329,7 @@ func (h *Handlers) buildDeliveryTasks(
 			DeliveryID:   dlv.ID,
 			EventID:      event.ID,
 			WebhookID:    entrypoint.WebhookID,
+			EntrypointID: entrypoint.ID,
 			TargetID:     targets[i].ID,
 			TargetName:   targets[i].Name,
 			TargetType:   targets[i].Type,

internal/middleware/middleware.go

@@ -265,6 +265,26 @@ func (s *Middleware) SecurityHeaders() func(http.Handler) http.Handler {
 	}
 }
 
+// NoCache returns middleware that instructs browsers and
+// intermediary proxies not to cache the response. It sets
+// Cache-Control: no-store and Pragma: no-cache (the latter for
+// older HTTP/1.0 intermediaries). Apply it to authenticated pages
+// so webhook configuration and captured event data are not stored
+// by caches.
+func (s *Middleware) NoCache() func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(
+			w http.ResponseWriter,
+			r *http.Request,
+		) {
+			w.Header().Set("Cache-Control", "no-store")
+			w.Header().Set("Pragma", "no-cache")
+
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
 // MaxBodySize returns middleware that limits the request body size
 // for POST requests. If the body exceeds the given limit in
 // bytes, the server returns 413 Request Entity Too Large. This

internal/middleware/middleware_test.go

@@ -387,6 +387,45 @@ func TestRequireAuth_UnauthenticatedSession_RedirectsToLogin(
 	assert.Equal(t, "/pages/login", w.Header().Get("Location"))
 }
 
+// --- NoCache Middleware Tests ---
+
+func TestNoCache_SetsHeaders(t *testing.T) {
+	t.Parallel()
+
+	m, _ := testMiddleware(t, config.EnvironmentDev)
+
+	var called bool
+
+	handler := m.NoCache()(http.HandlerFunc(
+		func(w http.ResponseWriter, _ *http.Request) {
+			called = true
+
+			w.WriteHeader(http.StatusOK)
+		},
+	))
+
+	req := httptest.NewRequestWithContext(
+		context.Background(),
+		http.MethodGet, "/sources", nil,
+	)
+	w := httptest.NewRecorder()
+
+	handler.ServeHTTP(w, req)
+
+	assert.True(
+		t, called,
+		"NoCache middleware should call the next handler",
+	)
+	assert.Equal(
+		t, "no-store",
+		w.Header().Get("Cache-Control"),
+	)
+	assert.Equal(
+		t, "no-cache",
+		w.Header().Get("Pragma"),
+	)
+}
+
 // --- Helper Tests ---
 
 func TestIpFromHostPort(t *testing.T) {

internal/middleware/ratelimit.go

@@ -14,6 +14,11 @@ const (
 
 	// loginRateInterval is the time window for the rate limit.
 	loginRateInterval = 1 * time.Minute
+
+	// receiverRateInterval is the time window for the webhook
+	// receiver rate limit. The configured limit is expressed in
+	// requests per minute.
+	receiverRateInterval = 1 * time.Minute
 )
 
 // LoginRateLimit returns middleware that enforces per-IP rate
@@ -62,3 +67,37 @@ func (m *Middleware) LoginRateLimit() func(http.Handler) http.Handler {
 		})
 	}
 }
+
+// ReceiverRateLimit returns middleware that rate-limits the
+// public webhook receiver endpoint per client IP per request
+// path (the path contains the entrypoint UUID, so each sender
+// is limited per entrypoint without affecting other senders or
+// other entrypoints). The limit is Config.ReceiverRateLimit
+// requests per minute. Requests over the limit receive a 429;
+// httprate adds the Retry-After header (RFC 6585). IP
+// extraction honours X-Forwarded-For, X-Real-IP, and
+// True-Client-IP headers for reverse-proxy setups.
+func (m *Middleware) ReceiverRateLimit() func(http.Handler) http.Handler {
+	return httprate.Limit(
+		m.params.Config.ReceiverRateLimit,
+		receiverRateInterval,
+		httprate.WithKeyFuncs(
+			httprate.KeyByRealIP,
+			httprate.KeyByEndpoint,
+		),
+		httprate.WithLimitHandler(http.HandlerFunc(
+			func(w http.ResponseWriter, r *http.Request) {
+				m.log.Warn(
+					"webhook receiver rate limit exceeded",
+					"path", r.URL.Path,
+				)
+				http.Error(
+					w,
+					"Too many requests. "+
+						"Please slow down.",
+					http.StatusTooManyRequests,
+				)
+			},
+		)),
+	)
+}

internal/middleware/ratelimit_test.go

@@ -2,8 +2,10 @@ package middleware_test
 
 import (
 	"context"
+	"log/slog"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -145,3 +147,94 @@ func TestLoginRateLimit_IndependentPerIP(t *testing.T) {
 		"different IP should not be affected",
 	)
 }
+
+// receiverLimitedHandler builds a ReceiverRateLimit-wrapped
+// handler with the given per-minute limit.
+func receiverLimitedHandler(
+	t *testing.T, limit int,
+) http.Handler {
+	t.Helper()
+
+	log := slog.New(slog.NewTextHandler(
+		os.Stderr,
+		&slog.HandlerOptions{Level: slog.LevelDebug},
+	))
+
+	m := middleware.NewForTest(
+		log,
+		&config.Config{ReceiverRateLimit: limit},
+		nil,
+	)
+
+	return m.ReceiverRateLimit()(http.HandlerFunc(
+		func(w http.ResponseWriter, _ *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		},
+	))
+}
+
+// receiverPost sends one POST to the handler from the given IP
+// and path and returns the recorder.
+func receiverPost(
+	handler http.Handler, ip, path string,
+) *httptest.ResponseRecorder {
+	req := httptest.NewRequestWithContext(
+		context.Background(),
+		http.MethodPost, path, nil,
+	)
+	req.RemoteAddr = ip
+
+	w := httptest.NewRecorder()
+	handler.ServeHTTP(w, req)
+
+	return w
+}
+
+func TestReceiverRateLimit_LimitsPerIPAndPath(t *testing.T) {
+	t.Parallel()
+
+	const limit = 3
+
+	handler := receiverLimitedHandler(t, limit)
+
+	// The first limit requests from one IP to one entrypoint
+	// pass.
+	for i := range limit {
+		w := receiverPost(
+			handler, "9.9.9.9:1234", "/webhook/uuid-a",
+		)
+		assert.Equal(
+			t, http.StatusOK, w.Code,
+			"request %d should pass", i,
+		)
+	}
+
+	// The next request over the limit is rejected with a 429
+	// carrying a Retry-After header.
+	w := receiverPost(
+		handler, "9.9.9.9:1234", "/webhook/uuid-a",
+	)
+	assert.Equal(t, http.StatusTooManyRequests, w.Code)
+	assert.NotEmpty(
+		t, w.Header().Get("Retry-After"),
+		"429 must carry a Retry-After header",
+	)
+
+	// The same IP is not limited on a different entrypoint.
+	w = receiverPost(
+		handler, "9.9.9.9:1234", "/webhook/uuid-b",
+	)
+	assert.Equal(
+		t, http.StatusOK, w.Code,
+		"a different entrypoint must not be affected",
+	)
+
+	// A different IP is not limited on the same entrypoint.
+	w = receiverPost(
+		handler, "8.8.8.8:1234", "/webhook/uuid-a",
+	)
+	assert.Equal(
+		t, http.StatusOK, w.Code,
+		"a different client IP must not be affected",
+	)
+}

internal/server/routes.go

@@ -91,6 +91,7 @@ func (s *Server) setupRoutes() {
 func (s *Server) setupPageRoutes() {
 	s.router.Route("/pages", func(r chi.Router) {
 		r.Use(s.mw.CSRF())
+		r.Use(s.mw.NoCache())
 		r.Use(s.mw.MaxBodySize(maxFormBodySize))
 
 		r.Group(func(r chi.Router) {
@@ -106,6 +107,7 @@ func (s *Server) setupPageRoutes() {
 func (s *Server) setupUserRoutes() {
 	s.router.Route("/user/{username}", func(r chi.Router) {
 		r.Use(s.mw.CSRF())
+		r.Use(s.mw.NoCache())
 		r.Use(s.mw.RequireAuth())
 		r.Get("/", s.h.HandleProfile())
 	})
@@ -114,6 +116,7 @@ func (s *Server) setupUserRoutes() {
 func (s *Server) setupSourceRoutes() {
 	s.router.Route("/sources", func(r chi.Router) {
 		r.Use(s.mw.CSRF())
+		r.Use(s.mw.NoCache())
 		r.Use(s.mw.RequireAuth())
 		r.Use(s.mw.MaxBodySize(maxFormBodySize))
 		r.Get("/", s.h.HandleSourceList())
@@ -123,6 +126,7 @@ func (s *Server) setupSourceRoutes() {
 
 	s.router.Route("/source/{sourceID}", func(r chi.Router) {
 		r.Use(s.mw.CSRF())
+		r.Use(s.mw.NoCache())
 		r.Use(s.mw.RequireAuth())
 		r.Use(s.mw.MaxBodySize(maxFormBodySize))
 		r.Get("/", s.h.HandleSourceDetail())
@@ -155,7 +159,7 @@ func (s *Server) setupSourceRoutes() {
 }
 
 func (s *Server) setupWebhookRoutes() {
-	s.router.HandleFunc(
+	s.router.With(s.mw.ReceiverRateLimit()).HandleFunc(
 		"/webhook/{uuid}",
 		s.h.HandleWebhook(),
 	)