Refactor delivery targets to a Target interface (closes #77) (#81)

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>

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,