Resubmit a stored event as a new undelivered event (closes #250)

README.md

@@ -903,10 +903,13 @@ webhooker solves this by acting as a durable intermediary:
    targets simultaneously. This enables patterns like forwarding a
    GitHub webhook to both a deployment service and a Slack channel.
 
-5. **Replay** (not yet implemented) — Every received event is stored in
-   full, which is what manual redelivery for debugging or testing will
-   be built on. No redelivery exists today, in the web UI or the API;
-   see [TODO.md](TODO.md).
+5. **Replay and resubmit** — Every received event is stored in full,
+   and the event log offers two redelivery actions built on that.
+   **Replay** re-sends one finished delivery to its own target, for
+   recovering a delivery that failed. **Resubmit** re-injects the stored
+   event as a new undelivered event and fans it out to every currently
+   active target, for firing captured traffic at a backend under
+   development. Both are web UI actions; there is no API for either.
 
 ### Use Cases
 
@@ -915,8 +918,8 @@ webhooker solves this by acting as a durable intermediary:
 - **Observability** via Prometheus metrics on webhook frequency, payload
   size, and delivery performance
 - **Debugging** and introspection of webhook payloads in the web UI
-- **Replay** of webhook events for application testing and development
-  (planned; not yet implemented)
+- **Resubmit** of captured webhook events for application testing and
+  development, and **replay** of a single failed delivery for recovery
 - **Fan-out** delivery of a single webhook to multiple downstream
   targets
 - **High-availability ingestion** for delivery to less reliable backend
@@ -1224,7 +1227,7 @@ A programmatic access credential for API authentication.
 #### Event
 
 A captured incoming webhook request. Stores the complete HTTP request
-data for auditing and for the planned replay capability.
+data for auditing, for replay, and for resubmission.
 
 | Field          | Type   | Description |
 | -------------- | ------ | ----------- |
@@ -1235,6 +1238,7 @@ data for auditing and for the planned replay capability.
 | `headers`      | JSON   | Complete request headers |
 | `body`         | text   | Raw request body |
 | `content_type` | string | Content-Type header value |
+| `resubmitted_from_id` | UUID | The event this one was copied from by a resubmit (nullable; empty for an event that arrived on the receiver). Not a foreign key: the source event can be reaped by retention while its copies remain |
 
 **Relations:** Belongs to Webhook. Belongs to Entrypoint. Has many
 Deliveries.
@@ -1283,6 +1287,30 @@ message on the event log rather than delivering from stale
 configuration, and a replay is refused while an earlier one for the
 same event and target is still pending or retrying.
 
+**Resubmit.** Replay recovers one delivery; **resubmit** re-injects one
+EVENT. The event log offers a per-event **Resubmit** action that stores
+a NEW event copying the stored one's `method`, `headers`, `body` and
+`content_type` verbatim, then fans it out to the webhook's currently
+**active** targets — resolved fresh by the same query the receiver
+uses, so a target created long after the original event arrived
+receives it. That is the difference that matters: a target added to
+test a backend under development has no prior delivery, so there is
+nothing to replay to it, while a resubmit reaches it like any other
+active target. Inactive targets are skipped, exactly as the receiver
+skips them.
+
+The new event is a first-class event in the log with its own
+deliveries, not a marker on the one it came from, and the original's
+deliveries are left untouched. It records `resubmitted_from_id`, and
+the event log shows the relationship both ways, so a captured event
+fired twenty times at a backend stays traceable. Resubmitting the same
+event repeatedly is supported and is the point of the action — there is
+no in-flight refusal; the route's own rate limit is what bounds it.
+
+Inbound signature verification is not re-run on a resubmit. There is no
+inbound signature to check on a copy the operator submits, and the
+route is authenticated and CSRF-protected as an operator action.
+
 #### DeliveryResult
 
 The result of a single delivery attempt. Every attempt (including
@@ -1539,10 +1567,11 @@ unknown) one while one of its deliveries is still `retrying`, both
 recovery paths above terminally mark that delivery `failed` and record a
 `DeliveryResult` naming the current target type as the reason, logging it
 at warn level. The delivery is not re-dispatched under the new type — the
-operator never asked for that delivery — and while the event itself
-remains stored in the per-webhook event database, there is no way to
-redeliver it: manual redelivery is planned, not implemented (see
-[TODO.md](TODO.md)).
+operator never asked for that delivery — and the event itself remains
+stored in the per-webhook event database. Nothing is lost: the delivery
+is `failed`, which is terminal, so the event log offers **Replay** on
+it to re-send it to that target under the new type, and **Resubmit** on
+the event to re-inject it to every currently active target.
 
 ### Circuit Breaker (HTTP and Slack Targets with Retries)
 
@@ -1615,13 +1644,16 @@ arriving and being stored, they are just not getting anywhere.
 | `webhooker_deliveries_failed_total` | counter | Deliveries that failed terminally and will not be retried |
 | `webhooker_delivery_retries_total` | counter | Deliveries put back into `retrying` |
 | `webhooker_delivery_replays_total` | counter | Deliveries an operator replayed from the event log. A replay runs the ordinary engine path, so it also moves the attempt, outcome and duration series; this is the only one that separates it from ordinary traffic |
+| `webhooker_events_resubmitted_total` | counter | Stored events an operator re-injected from the event log. The new event also moves `webhooker_events_received_total`, since it is a stored event the delivery side is compared against; this counter is what separates the two. Unlabelled: the target types it fans out to belong to the delivery series |
 | `webhooker_delivery_duration_seconds` | histogram | Wall time of a single dispatched delivery attempt, the same duration the attempt's `DeliveryResult` records |
 | `webhooker_deliveries_pending` | gauge | Deliveries currently in `pending` |
 | `webhooker_deliveries_retrying` | gauge | Deliveries currently in `retrying` |
 | `webhooker_circuit_breakers_open` | gauge | Circuit breakers currently open |
 
 Every delivery metric carries exactly one label, `target_type`, and
-cardinality is the whole reason for that restriction. A target type is
+cardinality is the whole reason for that restriction. The two
+event-level counters carry no label at all — an event is not the
+property of any one target type. A target type is
 one of four compile-time constants, so the label domain is bounded by
 construction; a value outside that set collapses to `unknown` rather
 than minting a series of its own. Target ids, event ids and entrypoint
@@ -2213,6 +2245,7 @@ abuse limit later; they are tracked as future work.
 | `POST` | `/source/{id}/delete`    | Delete webhook |
 | `GET`  | `/source/{id}/logs`      | Webhook event logs |
 | `POST` | `/source/{id}/deliveries/{deliveryID}/replay` | Replay a finished delivery: creates a new delivery for the same event against the target's current configuration (30 per minute per bucket, then `429`) |
+| `POST` | `/source/{id}/events/{eventID}/resubmit` | Resubmit a stored event: creates a new event copying it and fans that out to every currently active target (30 per minute per bucket, then `429`) |
 | `POST` | `/source/{id}/entrypoints` | Add entrypoint to webhook |
 | `POST` | `/source/{id}/entrypoints/{entrypointID}/delete` | Delete an entrypoint |
 | `POST` | `/source/{id}/entrypoints/{entrypointID}/toggle` | Enable or disable an entrypoint |
@@ -2303,6 +2336,7 @@ webhooker/
 │   │   ├── handlers.go        # Base handler struct, JSON helpers, template rendering
 │   │   ├── auth.go            # Login, logout handlers
 │   │   ├── delivery_replay.go # Per-delivery replay: new delivery, current target config
+│   │   ├── event_resubmit.go  # Event resubmit: new event, all currently active targets
 │   │   ├── entrypoint_view.go # Masked entrypoint view for templates
 │   │   ├── event_log_view.go  # Event log projection, byte-capped in SQL
 │   │   ├── healthcheck.go     # Health check handler

internal/database/model_event.go

@@ -13,6 +13,14 @@ type Event struct {
 	Body        string `gorm:"type:text"   json:"body"`
 	ContentType string `json:"contentType"`
 
+	// ResubmittedFromID names the event this one was copied from by
+	// an operator resubmit. It is nil for an event that arrived on
+	// the receiver, which is every event created before the column
+	// existed. It is not a foreign key: the source event can be
+	// reaped by retention while its copies remain, and the id is
+	// kept as the record of where the copy came from either way.
+	ResubmittedFromID *string `gorm:"type:uuid;index" json:"resubmittedFromId,omitempty"`
+
 	// Relations
 	Webhook    Webhook    `json:"webhook,omitzero"`
 	Entrypoint Entrypoint `json:"entrypoint,omitzero"`

internal/handlers/event_log_view.go

@@ -20,6 +20,7 @@ const maxRenderedBodyBytes = 8192
 // rather than in Go is the point of the projection — an
 // oversized body never becomes a Go string at all.
 const eventLogColumns = "id, created_at, method, content_type, " +
+	"resubmitted_from_id, " +
 	"substr(cast(body as blob), 1, ?) AS body, " +
 	"length(cast(body as blob)) AS body_bytes"
 
@@ -45,9 +46,25 @@ type EventLogView struct {
 	// than the cap, so the page owes the reader a marker.
 	BodyTruncated bool
 
+	// ResubmittedFromID names the event this one was copied
+	// from, empty for an event that arrived on the receiver.
+	ResubmittedFromID string
+
+	// ResubmitCount is how many events have been resubmitted
+	// from this one. Both directions are shown, because after
+	// a few resubmits of one captured event the log is
+	// otherwise a row of identical bodies with nothing saying
+	// which came from which.
+	ResubmitCount int
+
 	Deliveries []DeliveryView
 }
 
+// ResubmittedFrom reports that this event is a copy of another.
+func (v EventLogView) ResubmittedFrom() bool {
+	return v.ResubmittedFromID != ""
+}
+
 // BodyShownBytes is how many body bytes the page is actually
 // rendering, which the truncation marker reports beside the
 // true size.
@@ -59,12 +76,13 @@ func (v EventLogView) BodyShownBytes() int {
 // body column arrives already cut to the cap by SQLite, with
 // the true size beside it.
 type eventLogRow struct {
-	ID          string
-	CreatedAt   time.Time
-	Method      string
-	ContentType string
-	Body        []byte
-	BodyBytes   int64
+	ID                string
+	CreatedAt         time.Time
+	Method            string
+	ContentType       string
+	ResubmittedFromID *string
+	Body              []byte
+	BodyBytes         int64
 }
 
 // view projects a loaded row for rendering.
@@ -79,14 +97,20 @@ func (r *eventLogRow) view() EventLogView {
 		body = trimPartialRune(body)
 	}
 
+	var from string
+	if r.ResubmittedFromID != nil {
+		from = *r.ResubmittedFromID
+	}
+
 	return EventLogView{
-		ID:            r.ID,
-		CreatedAt:     r.CreatedAt,
-		Method:        r.Method,
-		ContentType:   r.ContentType,
-		Body:          string(body),
-		BodyBytes:     r.BodyBytes,
-		BodyTruncated: truncated,
+		ID:                r.ID,
+		CreatedAt:         r.CreatedAt,
+		Method:            r.Method,
+		ContentType:       r.ContentType,
+		Body:              string(body),
+		BodyBytes:         r.BodyBytes,
+		BodyTruncated:     truncated,
+		ResubmittedFromID: from,
 	}
 }
 

internal/handlers/event_resubmit.go

@@ -0,0 +1,277 @@
+package handlers
+
+import (
+	"errors"
+	"net/http"
+	"strconv"
+
+	"github.com/go-chi/chi"
+	"github.com/google/uuid"
+	"gorm.io/gorm"
+	"sneak.berlin/go/webhooker/internal/database"
+)
+
+// resubmitOutcomeParam is the query parameter the resubmit POST
+// redirects with and the event log page reads its banner from.
+const resubmitOutcomeParam = "resubmit"
+
+// resubmitOutcomeCode is the outcome of a resubmit POST. The redirect
+// carries one of these fixed codes rather than a message, so nothing a
+// client submits can reach the rendered page through it.
+type resubmitOutcomeCode string
+
+const (
+	// resubmitQueued reports that a new event was stored and its
+	// deliveries handed to the delivery engine.
+	resubmitQueued resubmitOutcomeCode = "queued"
+
+	// resubmitNoTargets reports a source with no active targets. The
+	// new event is stored either way, exactly as a received event
+	// with no targets is.
+	resubmitNoTargets resubmitOutcomeCode = "no-targets"
+)
+
+// resubmitOutcome returns the banner the event log page shows for an
+// outcome code, and whether the resubmit was queued. An unrecognised
+// code yields no banner.
+func resubmitOutcome(code string) (string, bool) {
+	switch resubmitOutcomeCode(code) {
+	case resubmitQueued:
+		return "Resubmitted: a new event was created from the stored " +
+			"one and queued to every active target.", true
+	case resubmitNoTargets:
+		return "Resubmitted: a new event was created, but this " +
+				"source has no active targets, so nothing was queued.",
+			true
+	default:
+		return "", false
+	}
+}
+
+// resubmitSource is the stored event a resubmit copies. Its body is
+// read as bytes rather than as a string so the copy is byte-identical
+// to what was received, whatever the payload's encoding.
+type resubmitSource struct {
+	ID           string
+	EntrypointID string
+	Method       string
+	Headers      string
+	ContentType  string
+	Body         []byte
+}
+
+// resubmitColumns is the projection resubmitSource is loaded through.
+// The cast to blob is what makes the driver hand back the stored bytes
+// rather than a string conversion, the same reason eventBodyQuery
+// casts.
+const resubmitColumns = "id, entrypoint_id, method, headers, " +
+	"content_type, cast(body as blob) AS body"
+
+// HandleEventResubmit re-injects a stored event as a new undelivered
+// event.
+//
+// This is the testing counterpart to per-delivery replay, and the two
+// select targets differently on purpose. A replay re-sends ONE
+// finished delivery to ITS OWN target, which is recovery. A resubmit
+// stores a NEW event copied from the stored one and fans it out to the
+// webhook's currently ACTIVE targets, resolved fresh by the query the
+// receiver uses — so a target created after the original event arrived
+// receives it, which is what makes capturing real traffic and firing
+// it at a backend under development possible. The original event's
+// deliveries have no bearing on where the copy goes.
+//
+// Nothing about the original delivery is re-sent: what is re-injected
+// is the stored EVENT. The response bodies and headers the original
+// deliveries received stay where they are.
+//
+// Inbound signature verification is deliberately not re-run. There is
+// no inbound signature to check on a copy the operator submits; the
+// route is authenticated and CSRF-protected as an operator action.
+//
+// Resubmitting the same event repeatedly is supported and is the point
+// of the feature, so replay's in-flight refusal is deliberately not
+// applied here. The route's rate limit is what bounds a held-down
+// button.
+func (h *Handlers) HandleEventResubmit() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		webhook, ok := h.ownedWebhook(w, r)
+		if !ok {
+			return
+		}
+
+		// The body size cap is enforced by the MaxBodySize
+		// middleware, which runs before CSRF parses the form.
+		err := r.ParseForm()
+		if err != nil {
+			http.Error(w, "Bad request", http.StatusBadRequest)
+
+			return
+		}
+
+		h.resubmitEvent(w, r, webhook)
+	}
+}
+
+// resubmitEvent performs the resubmit for a webhook the caller has
+// already established the session's user owns.
+func (h *Handlers) resubmitEvent(
+	w http.ResponseWriter,
+	r *http.Request,
+	webhook database.Webhook,
+) {
+	// Parsing the id before use keeps a malformed id out of the SQL
+	// and makes the value the query sees come from uuid's own fixed
+	// alphabet rather than from the request.
+	eventID, err := uuid.Parse(chi.URLParam(r, "eventID"))
+	if err != nil {
+		http.NotFound(w, r)
+
+		return
+	}
+
+	if !h.dbMgr.DBExists(webhook.ID) {
+		http.NotFound(w, r)
+
+		return
+	}
+
+	webhookDB, err := h.dbMgr.GetDB(webhook.ID)
+	if err != nil {
+		h.serverError(w, "failed to get webhook database", err)
+
+		return
+	}
+
+	// Read before the write transaction is opened. The body can be up
+	// to the 1 MB ingest cap, and holding a read of it inside the
+	// transaction would extend how long the per-webhook database is
+	// locked against the receiver, which runs these files in
+	// SQLite's default journal mode rather than WAL.
+	src, found, err := loadResubmitSource(
+		webhookDB, webhook.ID, eventID.String(),
+	)
+	if err != nil {
+		h.serverError(w, "failed to load event to resubmit", err)
+
+		return
+	}
+
+	// A miss is a 404 whether the event was reaped, belongs to
+	// another webhook, or never existed.
+	if !found {
+		http.NotFound(w, r)
+
+		return
+	}
+
+	h.queueResubmit(w, r, webhook, src)
+}
+
+// loadResubmitSource reads the stored event a resubmit copies, and
+// whether it exists within the webhook.
+//
+// The webhook_id predicate is currently redundant against the
+// per-webhook database files — a sibling webhook's event is not in the
+// database being queried at all — and is there so the scoping survives
+// any future change that puts more than one webhook's events in one
+// file. Going through Model applies GORM's soft-delete scope, which is
+// what stops a reaped event being resubmitted.
+func loadResubmitSource(
+	webhookDB *gorm.DB,
+	webhookID, eventID string,
+) (resubmitSource, bool, error) {
+	var src resubmitSource
+
+	err := webhookDB.Model(&database.Event{}).
+		Select(resubmitColumns).
+		Where("id = ? AND webhook_id = ?", eventID, webhookID).
+		First(&src).Error
+
+	if errors.Is(err, gorm.ErrRecordNotFound) {
+		return src, false, nil
+	}
+
+	if err != nil {
+		return src, false, err
+	}
+
+	return src, true, nil
+}
+
+// queueResubmit stores the copy and fans it out to the webhook's
+// active targets.
+func (h *Handlers) queueResubmit(
+	w http.ResponseWriter,
+	r *http.Request,
+	webhook database.Webhook,
+	src resubmitSource,
+) {
+	// The receiver's own query, run now: an active target created
+	// after the original event arrived is included, and an
+	// inactive one is skipped rather than refused.
+	targets, err := h.loadActiveTargets(webhook.ID)
+	if err != nil {
+		h.serverError(w, "failed to query targets", err)
+
+		return
+	}
+
+	event, tasks, err := h.createAndFanOut(
+		eventSource{
+			WebhookID:         webhook.ID,
+			EntrypointID:      src.EntrypointID,
+			Method:            src.Method,
+			HeadersJSON:       src.Headers,
+			ContentType:       src.ContentType,
+			Body:              src.Body,
+			ResubmittedFromID: &src.ID,
+		},
+		targets,
+	)
+	if err != nil {
+		h.serverError(w, "failed to store resubmitted event", err)
+
+		return
+	}
+
+	h.mtr.EventResubmitted()
+
+	h.log.Info(
+		"event resubmitted",
+		"webhook_id", webhook.ID,
+		"event_id", event.ID,
+		"resubmitted_from_id", src.ID,
+		"target_count", len(tasks),
+	)
+
+	code := resubmitQueued
+	if len(tasks) == 0 {
+		code = resubmitNoTargets
+	}
+
+	h.finishResubmit(w, r, webhook, code)
+}
+
+// finishResubmit redirects back to the event log the resubmit was
+// triggered from, carrying the outcome code the page turns into a
+// banner and the page number the form submitted.
+func (h *Handlers) finishResubmit(
+	w http.ResponseWriter,
+	r *http.Request,
+	webhook database.Webhook,
+	code resubmitOutcomeCode,
+) {
+	dest := "/source/" + webhook.ID + "/logs?" +
+		resubmitOutcomeParam + "=" + string(code)
+
+	// The page is read from the form rather than the query string:
+	// this is a POST, and its query string is what logs and Referer
+	// headers record.
+	if page := parseNonNegativeInt(
+		r.PostFormValue("page"),
+	); page > 1 {
+		dest += "&page=" + strconv.Itoa(page)
+	}
+
+	http.Redirect(w, r, dest, http.StatusSeeOther)
+}

internal/handlers/event_resubmit_test.go

@@ -0,0 +1,603 @@
+package handlers_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
+	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/delivery"
+	"sneak.berlin/go/webhooker/internal/handlers"
+	"sneak.berlin/go/webhooker/internal/session"
+)
+
+// resubmitTargetURL is a public destination, so a target configured
+// with it is one the SSRF guard would accept. Nothing in these tests
+// dispatches to it: the notifier is recorded, not run.
+const resubmitTargetURL = "http://93.184.216.34/hook"
+
+// resubmitEventHeaders is the stored header JSON a seeded event
+// carries, so a test can prove the copy takes it verbatim.
+const resubmitEventHeaders = `{"X-Test":["yes"],"X-Trace":["abc"]}`
+
+// seedStoredEvent records one event in a webhook's own database with
+// no deliveries at all, which is the state a captured event is in when
+// the operator has yet to create the target to test.
+func seedStoredEvent(
+	t *testing.T,
+	dbMgr *database.WebhookDBManager,
+	webhookID, body string,
+) *database.Event {
+	t.Helper()
+
+	webhookDB, err := dbMgr.GetDB(webhookID)
+	require.NoError(t, err)
+
+	event := &database.Event{
+		WebhookID:    webhookID,
+		EntrypointID: "entrypoint-" + webhookID,
+		Method:       http.MethodPost,
+		Headers:      resubmitEventHeaders,
+		Body:         body,
+		ContentType:  contentTypeJSON,
+	}
+
+	require.NoError(t, webhookDB.Omit(
+		clause.Associations,
+	).Create(event).Error)
+
+	return event
+}
+
+// postResubmit runs the real resubmit handler for one event.
+func postResubmit(
+	t *testing.T,
+	h *handlers.Handlers,
+	sess *session.Session,
+	webhookID, eventID string,
+) *httptest.ResponseRecorder {
+	t.Helper()
+
+	req := postRequest(
+		"/source/"+webhookID+"/events/"+eventID+"/resubmit",
+		authenticatedCookies(
+			t, sess, deleteTestUserID, deleteTestUsername,
+		),
+		map[string]string{
+			paramSourceID: webhookID,
+			paramEventID:  eventID,
+		},
+	)
+
+	w := httptest.NewRecorder()
+	h.HandleEventResubmit().ServeHTTP(w, req)
+
+	return w
+}
+
+// listEvents reads every event in a webhook's database, oldest first.
+func listEvents(
+	t *testing.T, webhookDB *gorm.DB,
+) []database.Event {
+	t.Helper()
+
+	var events []database.Event
+
+	require.NoError(t, webhookDB.
+		Order("created_at ASC, id ASC").
+		Find(&events).Error)
+
+	return events
+}
+
+// theOtherEvent returns the one event that is not excludeID.
+func theOtherEvent(
+	t *testing.T, events []database.Event, excludeID string,
+) database.Event {
+	t.Helper()
+
+	var found []database.Event
+
+	for _, e := range events {
+		if e.ID != excludeID {
+			found = append(found, e)
+		}
+	}
+
+	require.Len(t, found, 1)
+
+	return found[0]
+}
+
+// TestHandleEventResubmit_DeliversToTargetCreatedAfterTheEvent is the
+// core of the feature and the thing per-delivery replay cannot do: the
+// event was captured before the target existed, so it has no delivery
+// to replay, and the resubmit must still reach the new target.
+func TestHandleEventResubmit_DeliversToTargetCreatedAfterTheEvent(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+		notif *recordingNotifier
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr, &notif)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := seedWebhook(t, db)
+	original := seedStoredEvent(
+		t, dbMgr, wh.ID, `{"captured":"traffic"}`,
+	)
+
+	// The dev backend is registered only now, after the traffic was
+	// captured. It has no prior delivery of anything.
+	tgt := seedConfiguredTarget(
+		t, db, wh.ID, database.TargetTypeHTTP,
+		`{"url":"`+resubmitTargetURL+`"}`,
+	)
+
+	w := postResubmit(t, h, sess, wh.ID, original.ID)
+
+	require.Equal(t, http.StatusSeeOther, w.Code)
+	assert.Equal(
+		t,
+		"/source/"+wh.ID+"/logs?resubmit=queued",
+		w.Header().Get("Location"),
+	)
+
+	webhookDB, err := dbMgr.GetDB(wh.ID)
+	require.NoError(t, err)
+
+	events := listEvents(t, webhookDB)
+	require.Len(
+		t, events, 2,
+		"resubmit must create a new event, not mark the old one",
+	)
+
+	fresh := theOtherEvent(t, events, original.ID)
+	assertEventCopy(t, original, fresh)
+
+	// The delivery hangs off the NEW event, and the original event
+	// still has none.
+	assert.Empty(
+		t, listDeliveries(t, webhookDB, original.ID),
+		"the original event must be left untouched",
+	)
+
+	deliveries := listDeliveries(t, webhookDB, fresh.ID)
+	require.Len(t, deliveries, 1)
+	assert.Equal(t, tgt.ID, deliveries[0].TargetID)
+	assert.Equal(
+		t, database.DeliveryStatusPending, deliveries[0].Status,
+	)
+
+	tasks := notif.Tasks()
+	require.Len(t, tasks, 1)
+	assert.Equal(t, deliveries[0].ID, tasks[0].DeliveryID)
+	assertResubmitTask(t, tasks[0], wh.ID, &fresh, tgt)
+
+	assertNoLeakedTarget(t, webhookDB)
+}
+
+// assertEventCopy proves the resubmitted event copies every stored
+// field of the event it came from, and records the provenance that
+// keeps the log readable. It also pins that a received event carries
+// no source event of its own.
+func assertEventCopy(
+	t *testing.T, original *database.Event, fresh database.Event,
+) {
+	t.Helper()
+
+	assert.Equal(t, original.Method, fresh.Method)
+	assert.Equal(t, original.Headers, fresh.Headers)
+	assert.Equal(t, original.Body, fresh.Body)
+	assert.Equal(t, original.ContentType, fresh.ContentType)
+	assert.Equal(t, original.EntrypointID, fresh.EntrypointID)
+	assert.Equal(t, original.WebhookID, fresh.WebhookID)
+	assert.NotEqual(t, original.ID, fresh.ID)
+
+	require.NotNil(t, fresh.ResubmittedFromID)
+	assert.Equal(t, original.ID, *fresh.ResubmittedFromID)
+
+	assert.Nil(
+		t, original.ResubmittedFromID,
+		"a received event records no source event",
+	)
+}
+
+// assertResubmitTask proves the task handed to the delivery engine is
+// the one the receiver would build for the NEW event and this target.
+func assertResubmitTask(
+	t *testing.T,
+	task delivery.Task,
+	webhookID string,
+	fresh *database.Event,
+	target *database.Target,
+) {
+	t.Helper()
+
+	assert.Equal(t, fresh.ID, task.EventID)
+	assert.Equal(t, webhookID, task.WebhookID)
+	assert.Equal(t, fresh.EntrypointID, task.EntrypointID)
+	assert.Equal(t, target.ID, task.TargetID)
+	assert.Equal(t, target.Type, task.TargetType)
+	assert.Equal(t, fresh.Method, task.Method)
+	assert.Equal(t, fresh.Headers, task.Headers)
+	assert.Equal(t, fresh.ContentType, task.ContentType)
+	assert.Equal(t, 1, task.AttemptNum)
+
+	require.NotNil(t, task.Body)
+	assert.Equal(t, fresh.Body, *task.Body)
+}
+
+// TestHandleEventResubmit_IsRepeatable proves the requirement replay
+// deliberately does not meet: firing the same captured event at a
+// backend over and over must work, with no in-flight refusal, and each
+// press must produce its own event and its own delivery.
+func TestHandleEventResubmit_IsRepeatable(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+		notif *recordingNotifier
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr, &notif)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := seedWebhook(t, db)
+	tgt := seedConfiguredTarget(
+		t, db, wh.ID, database.TargetTypeHTTP,
+		`{"url":"`+resubmitTargetURL+`"}`,
+	)
+	original := seedStoredEvent(t, dbMgr, wh.ID, `{"fire":"again"}`)
+
+	// Nothing between the presses marks the earlier deliveries
+	// finished, so every one of these is submitted while the last is
+	// still pending.
+	const presses = 5
+
+	for range presses {
+		w := postResubmit(t, h, sess, wh.ID, original.ID)
+
+		require.Equal(t, http.StatusSeeOther, w.Code)
+		assert.Equal(
+			t,
+			"/source/"+wh.ID+"/logs?resubmit=queued",
+			w.Header().Get("Location"),
+			"a resubmit must not be refused while an earlier "+
+				"one is in flight",
+		)
+	}
+
+	webhookDB, err := dbMgr.GetDB(wh.ID)
+	require.NoError(t, err)
+
+	events := listEvents(t, webhookDB)
+	require.Len(t, events, presses+1)
+
+	tasks := notif.Tasks()
+	require.Len(t, tasks, presses)
+
+	seen := make(map[string]struct{}, presses)
+
+	for _, task := range tasks {
+		assert.Equal(t, tgt.ID, task.TargetID)
+		assert.NotEqual(
+			t, original.ID, task.EventID,
+			"each resubmit delivers its own new event",
+		)
+
+		_, dup := seen[task.EventID]
+		assert.False(t, dup, "each resubmit creates its own event")
+
+		seen[task.EventID] = struct{}{}
+
+		require.Len(t, listDeliveries(t, webhookDB, task.EventID), 1)
+	}
+
+	// Every copy names the same source event, so twenty presses stay
+	// traceable to the one captured request.
+	for _, e := range events {
+		if e.ID == original.ID {
+			continue
+		}
+
+		require.NotNil(t, e.ResubmittedFromID)
+		assert.Equal(t, original.ID, *e.ResubmittedFromID)
+	}
+}
+
+// TestHandleEventResubmit_OversizeBodySurvivesIntact covers the
+// non-inline case: a body above delivery.MaxInlineBodySize is not
+// carried on the task at all, so it has to be copied into the new
+// event row byte-identically for the engine to load it from there.
+func TestHandleEventResubmit_OversizeBodySurvivesIntact(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+		notif *recordingNotifier
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr, &notif)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	// Well over the inline limit, and not text: a multibyte rune, a
+	// NUL and a byte that is not valid UTF-8, so a copy that went
+	// through a re-encode or a truncation is visible in the compare.
+	const sentinel = "TAIL-SENTINEL-1f4a9c"
+
+	stored := strings.Repeat("A", delivery.MaxInlineBodySize) +
+		"é\x00\xff" +
+		strings.Repeat("B", 4096) + sentinel
+
+	require.Greater(t, len(stored), delivery.MaxInlineBodySize)
+
+	wh := seedWebhook(t, db)
+	seedConfiguredTarget(
+		t, db, wh.ID, database.TargetTypeHTTP,
+		`{"url":"`+resubmitTargetURL+`"}`,
+	)
+	original := seedStoredEvent(t, dbMgr, wh.ID, stored)
+
+	w := postResubmit(t, h, sess, wh.ID, original.ID)
+	require.Equal(t, http.StatusSeeOther, w.Code)
+
+	webhookDB, err := dbMgr.GetDB(wh.ID)
+	require.NoError(t, err)
+
+	fresh := theOtherEvent(t, listEvents(t, webhookDB), original.ID)
+
+	assert.Len(t, fresh.Body, len(stored))
+	assert.Equal(
+		t, stored, fresh.Body,
+		"the stored body must be copied byte for byte",
+	)
+
+	tasks := notif.Tasks()
+	require.Len(t, tasks, 1)
+	assert.Nil(
+		t, tasks[0].Body,
+		"a body over the inline limit is fetched from the new "+
+			"event row rather than carried on the task",
+	)
+
+	// The engine's own read of the body, against the new event id:
+	// what it would send is what was stored.
+	var loaded database.Event
+
+	require.NoError(t, webhookDB.Select("body").
+		First(&loaded, "id = ?", tasks[0].EventID).Error)
+	assert.Equal(t, stored, loaded.Body)
+}
+
+// TestHandleEventResubmit_SkipsInactiveTarget proves a deactivated
+// target is skipped exactly as the receiver skips it — not an error,
+// and not a delivery the operator switched off.
+func TestHandleEventResubmit_SkipsInactiveTarget(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+		notif *recordingNotifier
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr, &notif)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := seedWebhook(t, db)
+	active := seedConfiguredTarget(
+		t, db, wh.ID, database.TargetTypeHTTP,
+		`{"url":"`+resubmitTargetURL+`"}`,
+	)
+	off := seedConfiguredTarget(
+		t, db, wh.ID, database.TargetTypeHTTP,
+		`{"url":"`+resubmitTargetURL+`/off"}`,
+	)
+
+	require.NoError(t, db.DB().Model(&database.Target{}).
+		Where("id = ?", off.ID).
+		Update("active", false).Error)
+
+	original := seedStoredEvent(t, dbMgr, wh.ID, `{"skip":"one"}`)
+
+	w := postResubmit(t, h, sess, wh.ID, original.ID)
+
+	require.Equal(t, http.StatusSeeOther, w.Code)
+	assert.Equal(
+		t,
+		"/source/"+wh.ID+"/logs?resubmit=queued",
+		w.Header().Get("Location"),
+		"an inactive target is skipped, not an error",
+	)
+
+	tasks := notif.Tasks()
+	require.Len(t, tasks, 1)
+	assert.Equal(t, active.ID, tasks[0].TargetID)
+
+	webhookDB, err := dbMgr.GetDB(wh.ID)
+	require.NoError(t, err)
+
+	fresh := theOtherEvent(t, listEvents(t, webhookDB), original.ID)
+	require.Len(t, listDeliveries(t, webhookDB, fresh.ID), 1)
+}
+
+// TestHandleEventResubmit_NoActiveTargetsStillStoresEvent proves a
+// source with nothing to deliver to behaves as the receiver does: the
+// event is stored, nothing is queued, and the operator is told so
+// rather than being shown an error.
+func TestHandleEventResubmit_NoActiveTargetsStillStoresEvent(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+		notif *recordingNotifier
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr, &notif)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := seedWebhook(t, db)
+	original := seedStoredEvent(t, dbMgr, wh.ID, `{"no":"targets"}`)
+
+	w := postResubmit(t, h, sess, wh.ID, original.ID)
+
+	require.Equal(t, http.StatusSeeOther, w.Code)
+	assert.Equal(
+		t,
+		"/source/"+wh.ID+"/logs?resubmit=no-targets",
+		w.Header().Get("Location"),
+	)
+
+	assert.Empty(t, notif.Tasks())
+
+	webhookDB, err := dbMgr.GetDB(wh.ID)
+	require.NoError(t, err)
+
+	assert.Len(t, listEvents(t, webhookDB), 2)
+}
+
+// TestHandleEventResubmit_RefusesEventOfAnotherWebhook proves the
+// route cannot re-inject an event out of a webhook the session's user
+// does not own, and reports the same 404 for an id that names nothing.
+func TestHandleEventResubmit_RefusesEventOfAnotherWebhook(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+		notif *recordingNotifier
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr, &notif)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	theirs := seedWebhookFor(t, db, otherTestUserID)
+	theirEvent := seedStoredEvent(t, dbMgr, theirs.ID, `{"not":"mine"}`)
+
+	mine := seedWebhook(t, db)
+	seedConfiguredTarget(
+		t, db, mine.ID, database.TargetTypeHTTP,
+		`{"url":"`+resubmitTargetURL+`"}`,
+	)
+	seedStoredEvent(t, dbMgr, mine.ID, `{"mine":true}`)
+
+	// Their webhook, as its owner would address it.
+	w := postResubmit(t, h, sess, theirs.ID, theirEvent.ID)
+	assert.Equal(t, http.StatusNotFound, w.Code)
+
+	// Their event id, addressed through a webhook the user does own.
+	w = postResubmit(t, h, sess, mine.ID, theirEvent.ID)
+	assert.Equal(t, http.StatusNotFound, w.Code)
+
+	// An id that names no event at all.
+	w = postResubmit(t, h, sess, mine.ID, uuid.NewString())
+	assert.Equal(t, http.StatusNotFound, w.Code)
+
+	// A malformed id never reaches the query.
+	w = postResubmit(t, h, sess, mine.ID, "not-a-uuid")
+	assert.Equal(t, http.StatusNotFound, w.Code)
+
+	assert.Empty(
+		t, notif.Tasks(),
+		"a refused resubmit must queue nothing",
+	)
+}
+
+// TestHandleSourceLogs_ShowsResubmitProvenance proves the event log
+// reports the relationship in both directions, which is what keeps it
+// readable once one captured event has been fired repeatedly.
+func TestHandleSourceLogs_ShowsResubmitProvenance(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := seedWebhook(t, db)
+	seedConfiguredTarget(
+		t, db, wh.ID, database.TargetTypeHTTP,
+		`{"url":"`+resubmitTargetURL+`"}`,
+	)
+	original := seedStoredEvent(t, dbMgr, wh.ID, `{"trace":"me"}`)
+
+	for range 2 {
+		require.Equal(
+			t,
+			http.StatusSeeOther,
+			postResubmit(t, h, sess, wh.ID, original.ID).Code,
+		)
+	}
+
+	webhookDB, err := dbMgr.GetDB(wh.ID)
+	require.NoError(t, err)
+
+	events := listEvents(t, webhookDB)
+	require.Len(t, events, 3)
+
+	body := renderSourceLogsPage(t, h, sess, wh.ID)
+
+	assert.Contains(
+		t, body, "Resubmitted as 2 new events",
+		"the source event must show it has been resubmitted",
+	)
+	assert.Contains(
+		t, body, "Resubmitted from event",
+		"a copy must show where it came from",
+	)
+	assert.Contains(
+		t, body,
+		"/source/"+wh.ID+"/events/"+original.ID+"/resubmit",
+		"the log must offer the resubmit action per event",
+	)
+}

internal/handlers/source_management.go

@@ -821,25 +821,31 @@ func (h *Handlers) HandleSourceLogs() http.HandlerFunc {
 			totalPages++
 		}
 
-		// The banner a replay POST redirected back with. The
-		// message comes from a fixed set keyed by the outcome
-		// code, never from the query string itself.
+		// The banner a replay or resubmit POST redirected back
+		// with. The message comes from a fixed set keyed by the
+		// outcome code, never from the query string itself.
 		replayMsg, replayOK := replayOutcome(
 			r.URL.Query().Get(replayOutcomeParam),
 		)
 
+		resubmitMsg, resubmitOK := resubmitOutcome(
+			r.URL.Query().Get(resubmitOutcomeParam),
+		)
+
 		data := map[string]any{
-			tmplKeyWebhook:  &webhook,
-			"Events":        evts,
-			"ReplayMessage": replayMsg,
-			"ReplayQueued":  replayOK,
-			"Page":          page,
-			"TotalPages":    totalPages,
-			"TotalEvents":   total,
-			"HasPrev":       page > 1,
-			"HasNext":       page < totalPages,
-			"PrevPage":      page - 1,
-			"NextPage":      page + 1,
+			tmplKeyWebhook:    &webhook,
+			"Events":          evts,
+			"ReplayMessage":   replayMsg,
+			"ReplayQueued":    replayOK,
+			"ResubmitMessage": resubmitMsg,
+			"ResubmitQueued":  resubmitOK,
+			"Page":            page,
+			"TotalPages":      totalPages,
+			"TotalEvents":     total,
+			"HasPrev":         page > 1,
+			"HasNext":         page < totalPages,
+			"PrevPage":        page - 1,
+			"NextPage":        page + 1,
 		}
 
 		h.renderTemplate(w, r, "source_logs.html", data)
@@ -925,12 +931,10 @@ func (h *Handlers) loadEventsWithDeliveries(
 	targetMap map[string]eventLogTarget,
 	page int,
 ) ([]EventLogView, int64, bool) {
-	var totalEvents int64
-
 	var result []EventLogView
 
 	if !h.dbMgr.DBExists(webhook.ID) {
-		return result, totalEvents, true
+		return result, 0, true
 	}
 
 	webhookDB, err := h.dbMgr.GetDB(webhook.ID)
@@ -942,29 +946,20 @@ func (h *Handlers) loadEventsWithDeliveries(
 		return nil, 0, false
 	}
 
-	webhookDB.Model(&database.Event{}).Where(
-		"webhook_id = ?", webhook.ID,
-	).Count(&totalEvents)
-
-	offset := (page - 1) * paginationPerPage
-
-	var rows []eventLogRow
-
-	webhookDB.Model(&database.Event{}).Select(
-		eventLogColumns, maxRenderedBodyBytes,
-	).Where(
-		"webhook_id = ?", webhook.ID,
-	).Order("created_at DESC").Offset(offset).Limit(
-		paginationPerPage,
-	).Find(&rows)
+	rows, totalEvents := loadEventLogRows(
+		webhookDB, webhook.ID, page,
+	)
 
 	result = make([]EventLogView, len(rows))
 	eventDeliveries := make([][]database.Delivery, len(rows))
 
 	var deliveryIDs []string
 
+	eventIDs := make([]string, len(rows))
+
 	for i := range rows {
 		result[i] = rows[i].view()
+		eventIDs[i] = rows[i].ID
 
 		webhookDB.Where(
 			"event_id = ?", rows[i].ID,
@@ -988,15 +983,86 @@ func (h *Handlers) loadEventsWithDeliveries(
 		return nil, 0, false
 	}
 
+	resubmits, err := resubmitCounts(webhookDB, eventIDs)
+	if err != nil {
+		h.serverError(
+			w, "failed to count event resubmissions", err,
+		)
+
+		return nil, 0, false
+	}
+
 	for i := range rows {
 		result[i].Deliveries = newDeliveryViews(
 			eventDeliveries[i], targetMap, attempts,
 		)
+		result[i].ResubmitCount = resubmits[rows[i].ID]
 	}
 
 	return result, totalEvents, true
 }
 
+// loadEventLogRows reads one page of the event log projection, newest
+// first, and the total number of events the pager counts against.
+func loadEventLogRows(
+	webhookDB *gorm.DB, webhookID string, page int,
+) ([]eventLogRow, int64) {
+	var totalEvents int64
+
+	webhookDB.Model(&database.Event{}).Where(
+		"webhook_id = ?", webhookID,
+	).Count(&totalEvents)
+
+	var rows []eventLogRow
+
+	webhookDB.Model(&database.Event{}).Select(
+		eventLogColumns, maxRenderedBodyBytes,
+	).Where(
+		"webhook_id = ?", webhookID,
+	).Order("created_at DESC").Offset(
+		(page - 1) * paginationPerPage,
+	).Limit(paginationPerPage).Find(&rows)
+
+	return rows, totalEvents
+}
+
+// resubmitCounts reports, for each of the page's events, how many
+// events have been resubmitted from it.
+//
+// One grouped query covers the page rather than one query per event.
+// A page holds paginationPerPage ids, far below SQLite's bound
+// parameter ceiling, so it needs no chunking as the delivery result
+// load does.
+func resubmitCounts(
+	webhookDB *gorm.DB, eventIDs []string,
+) (map[string]int, error) {
+	counts := make(map[string]int, len(eventIDs))
+
+	if len(eventIDs) == 0 {
+		return counts, nil
+	}
+
+	var rows []struct {
+		ResubmittedFromID string
+		Total             int
+	}
+
+	err := webhookDB.Model(&database.Event{}).
+		Select("resubmitted_from_id, count(*) AS total").
+		Where("resubmitted_from_id IN ?", eventIDs).
+		Group("resubmitted_from_id").
+		Find(&rows).Error
+	if err != nil {
+		return nil, err
+	}
+
+	for _, row := range rows {
+		counts[row.ResubmittedFromID] = row.Total
+	}
+
+	return counts, nil
+}
+
 // deliveryIDChunkSize bounds how many delivery IDs go into one
 // IN clause. SQLite refuses a statement carrying more than
 // SQLITE_MAX_VARIABLE_NUMBER (32766) bound parameters, and a

internal/handlers/webhook.go

@@ -3,6 +3,7 @@ package handlers
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"net/http"
 
@@ -255,8 +256,8 @@ func (h *Handlers) readWebhookBody(
 	return body, true
 }
 
-// createAndDeliverEvent creates the event and delivery records
-// then notifies the delivery engine.
+// createAndDeliverEvent stores the received event, fans it out to the
+// webhook's targets, and answers the sender.
 func (h *Handlers) createAndDeliverEvent(
 	w http.ResponseWriter,
 	r *http.Request,
@@ -264,69 +265,130 @@ func (h *Handlers) createAndDeliverEvent(
 	body, headersJSON []byte,
 	targets []database.Target,
 ) {
-	tx, err := h.beginWebhookTx(w, entrypoint.WebhookID)
-	if err != nil {
-		return
-	}
-
-	event := h.buildEvent(r, entrypoint, headersJSON, body)
-
-	err = tx.Create(event).Error
-	if err != nil {
-		tx.Rollback()
-		h.serverError(w, "failed to create event", err)
-
-		return
-	}
-
-	bodyPtr := inlineBody(body)
-
-	tasks := h.buildDeliveryTasks(
-		w, tx, event, entrypoint, targets, bodyPtr,
+	event, tasks, err := h.createAndFanOut(
+		requestEventSource(r, entrypoint, headersJSON, body),
+		targets,
 	)
-	if tasks == nil {
-		return
-	}
-
-	err = tx.Commit().Error
 	if err != nil {
-		h.serverError(w, "failed to commit transaction", err)
+		h.serverError(w, "failed to store webhook event", err)
 
 		return
 	}
 
-	// Counted here, after the commit: an event is received once it
-	// is durably stored, which is what the delivery counters are
-	// compared against on a dashboard.
-	h.mtr.EventReceived()
-
 	h.finishWebhookResponse(w, event, entrypoint, tasks)
 }
 
-// beginWebhookTx opens a transaction on the per-webhook DB.
-func (h *Handlers) beginWebhookTx(
-	w http.ResponseWriter,
-	webhookID string,
-) (*gorm.DB, error) {
-	webhookDB, err := h.dbMgr.GetDB(webhookID)
-	if err != nil {
-		h.serverError(
-			w, "failed to get webhook database", err,
-		)
+// eventSource carries the fields a new event is built from. The
+// receiver fills it from the live request; the resubmit handler fills
+// it from a stored event. Both then go through createAndFanOut, so an
+// event is constructed and fanned out in one place however it entered
+// the system.
+type eventSource struct {
+	WebhookID    string
+	EntrypointID string
+	Method       string
+	HeadersJSON  string
+	ContentType  string
+	Body         []byte
 
-		return nil, err
+	// ResubmittedFromID names the event this one copies. Only the
+	// resubmit path sets it.
+	ResubmittedFromID *string
+}
+
+// event builds the row this source stores.
+func (s eventSource) event() *database.Event {
+	return &database.Event{
+		WebhookID:         s.WebhookID,
+		EntrypointID:      s.EntrypointID,
+		Method:            s.Method,
+		Headers:           s.HeadersJSON,
+		Body:              string(s.Body),
+		ContentType:       s.ContentType,
+		ResubmittedFromID: s.ResubmittedFromID,
+	}
+}
+
+// requestEventSource describes the event a live receiver request
+// stores.
+func requestEventSource(
+	r *http.Request,
+	entrypoint database.Entrypoint,
+	headersJSON, body []byte,
+) eventSource {
+	return eventSource{
+		WebhookID:    entrypoint.WebhookID,
+		EntrypointID: entrypoint.ID,
+		Method:       r.Method,
+		HeadersJSON:  string(headersJSON),
+		ContentType:  r.Header.Get("Content-Type"),
+		Body:         body,
+	}
+}
+
+// createAndFanOut writes the event and one pending delivery per target
+// in a single transaction, then hands the tasks to the delivery
+// engine. It is the only path by which an event and its deliveries are
+// created, so a resubmitted event is retried, SSRF-guarded and
+// circuit-broken exactly as a received one is.
+//
+// The tasks are returned as well as queued, so a caller can report how
+// many targets the event went to.
+func (h *Handlers) createAndFanOut(
+	src eventSource,
+	targets []database.Target,
+) (*database.Event, []delivery.Task, error) {
+	webhookDB, err := h.dbMgr.GetDB(src.WebhookID)
+	if err != nil {
+		return nil, nil, fmt.Errorf(
+			"getting webhook database: %w", err,
+		)
 	}
 
 	tx := webhookDB.Begin()
 	if tx.Error != nil {
-		h.serverError(
-			w, "failed to begin transaction", tx.Error,
+		return nil, nil, fmt.Errorf(
+			"beginning transaction: %w", tx.Error,
 		)
-
-		return nil, tx.Error
 	}
 
-	return tx, nil
+	event := src.event()
+
+	err = tx.Create(event).Error
+	if err != nil {
+		tx.Rollback()
+
+		return nil, nil, fmt.Errorf("creating event: %w", err)
+	}
+
+	tasks, err := buildDeliveryTasks(
+		tx, event, targets, inlineBody(src.Body),
+	)
+	if err != nil {
+		tx.Rollback()
+
+		return nil, nil, err
+	}
+
+	err = tx.Commit().Error
+	if err != nil {
+		return nil, nil, fmt.Errorf(
+			"committing transaction: %w", err,
+		)
+	}
+
+	// Counted here, after the commit: an event exists once it is
+	// durably stored, which is what the delivery counters are
+	// compared against on a dashboard. A resubmitted event counts
+	// too, because it produces deliveries that the delivery side
+	// counts; the resubmit counter is what separates the two.
+	h.mtr.EventReceived()
+
+	if len(tasks) > 0 {
+		h.notifier.Notify(tasks)
+	}
+
+	return event, tasks, nil
 }
 
 // inlineBody returns a pointer to body as a string if it fits
@@ -341,18 +403,13 @@ func inlineBody(body []byte) *string {
 	return nil
 }
 
-// finishWebhookResponse notifies the delivery engine, logs the
-// event, and writes the HTTP response.
+// finishWebhookResponse logs the event and writes the HTTP response.
 func (h *Handlers) finishWebhookResponse(
 	w http.ResponseWriter,
 	event *database.Event,
 	entrypoint database.Entrypoint,
 	tasks []delivery.Task,
 ) {
-	if len(tasks) > 0 {
-		h.notifier.Notify(tasks)
-	}
-
 	h.log.Info("webhook event created",
 		"event_id", event.ID,
 		"webhook_id", entrypoint.WebhookID,
@@ -370,33 +427,15 @@ func (h *Handlers) finishWebhookResponse(
 	}
 }
 
-// buildEvent creates a new Event struct from request data.
-func (h *Handlers) buildEvent(
-	r *http.Request,
-	entrypoint database.Entrypoint,
-	headersJSON, body []byte,
-) *database.Event {
-	return &database.Event{
-		WebhookID:    entrypoint.WebhookID,
-		EntrypointID: entrypoint.ID,
-		Method:       r.Method,
-		Headers:      string(headersJSON),
-		Body:         string(body),
-		ContentType:  r.Header.Get("Content-Type"),
-	}
-}
-
-// buildDeliveryTasks creates delivery records in the
-// transaction and returns tasks for the delivery engine.
-// Returns nil if an error occurred.
-func (h *Handlers) buildDeliveryTasks(
-	w http.ResponseWriter,
+// buildDeliveryTasks creates one pending delivery per target in the
+// transaction and returns the tasks for the delivery engine. The
+// caller owns the transaction and rolls it back on error.
+func buildDeliveryTasks(
 	tx *gorm.DB,
 	event *database.Event,
-	entrypoint database.Entrypoint,
 	targets []database.Target,
 	bodyPtr *string,
-) []delivery.Task {
+) ([]delivery.Task, error) {
 	tasks := make([]delivery.Task, 0, len(targets))
 
 	for i := range targets {
@@ -408,25 +447,17 @@ func (h *Handlers) buildDeliveryTasks(
 
 		err := tx.Create(dlv).Error
 		if err != nil {
-			tx.Rollback()
-			h.log.Error(
-				"failed to create delivery",
-				"target_id", targets[i].ID,
-				"error", err,
+			return nil, fmt.Errorf(
+				"creating delivery for target %s: %w",
+				targets[i].ID, err,
 			)
-			http.Error(
-				w, "Internal server error",
-				http.StatusInternalServerError,
-			)
-
-			return nil
 		}
 
 		tasks = append(tasks, delivery.Task{
 			DeliveryID:   dlv.ID,
 			EventID:      event.ID,
-			WebhookID:    entrypoint.WebhookID,
-			EntrypointID: entrypoint.ID,
+			WebhookID:    event.WebhookID,
+			EntrypointID: event.EntrypointID,
 			TargetID:     targets[i].ID,
 			TargetName:   targets[i].Name,
 			TargetType:   targets[i].Type,
@@ -440,5 +471,5 @@ func (h *Handlers) buildDeliveryTasks(
 		})
 	}
 
-	return tasks
+	return tasks, nil
 }

internal/metrics/metrics.go

@@ -83,6 +83,7 @@ type Set struct {
 	deliveriesFailed    *prometheus.CounterVec
 	deliveryRetries     *prometheus.CounterVec
 	deliveryReplays     *prometheus.CounterVec
+	eventsResubmitted   prometheus.Counter
 	deliveryDuration    *prometheus.HistogramVec
 	deliveriesPending   *prometheus.GaugeVec
 	deliveriesRetrying  *prometheus.GaugeVec
@@ -166,6 +167,23 @@ func (s *Set) DeliveryReplayed(t database.TargetType) {
 		Inc()
 }
 
+// EventResubmitted counts one stored event an operator re-injected
+// from the event log.
+//
+// It counts the operator action once, not the deliveries it fans out
+// to: those already move the attempt, outcome and duration series, and
+// the new event moves events_received_total, since it is a stored
+// event that the delivery side will be compared against. This counter
+// is what separates a resubmitted event from a received one.
+//
+// It carries no labels. The only label available at the call site
+// would be the route pattern, which has exactly one value and so would
+// distinguish nothing; the target types the event fans out to belong
+// to the delivery series, not to this one.
+func (s *Set) EventResubmitted() {
+	s.eventsResubmitted.Inc()
+}
+
 // DeliveryStatusChanged counts a delivery's transition into a new
 // status. The mapping from status to counter lives here, next to the
 // collectors, so the engine has a single call for every transition it
@@ -298,6 +316,15 @@ func (s *Set) registerCounters(factory promauto.Factory) {
 		},
 		[]string{targetTypeLabel},
 	)
+
+	s.eventsResubmitted = factory.NewCounter(
+		prometheus.CounterOpts{
+			Namespace: namespace,
+			Name:      "events_resubmitted_total",
+			Help: "Stored events an operator re-injected from " +
+				"the event log as new events.",
+		},
+	)
 }
 
 func (s *Set) registerGauges(factory promauto.Factory) {

internal/middleware/ratelimit.go

@@ -44,6 +44,18 @@ const (
 	// replayRateInterval is the time window for the replay limit.
 	replayRateInterval = 1 * time.Minute
 
+	// resubmitRateLimit is the maximum number of event resubmits one
+	// client may queue per interval. A resubmit stores an event and
+	// queues one delivery per active target, so it costs more
+	// outbound work per press than a replay does. Firing a captured
+	// event repeatedly at a backend under development is the point of
+	// the action, so the ceiling stays well above the rate a person
+	// iterates at.
+	resubmitRateLimit = 30
+
+	// resubmitRateInterval is the time window for the resubmit limit.
+	resubmitRateInterval = 1 * time.Minute
+
 	// receiverRateInterval is the time window for the webhook
 	// receiver rate limit. The configured limit is expressed in
 	// requests per minute.
@@ -315,6 +327,22 @@ func (m *Middleware) ReplayRateLimit() func(http.Handler) http.Handler {
 	)
 }
 
+// ResubmitRateLimit returns middleware that enforces per-IP rate
+// limiting on event resubmits.
+//
+// It is a separate bucket from the replay limit so that exhausting one
+// does not take the other away: replay is a recovery action and
+// resubmit is a testing action, and an operator iterating on a backend
+// must not lose the ability to re-send a failed delivery.
+func (m *Middleware) ResubmitRateLimit() func(http.Handler) http.Handler {
+	return m.postRateLimit(
+		resubmitRateLimit,
+		resubmitRateInterval,
+		"event resubmit rate limit exceeded",
+		"Too many resubmits. Please try again later.",
+	)
+}
+
 // postRateLimit builds middleware that enforces a per-IP rate
 // limit on POST requests only; all other methods pass through
 // unaffected. Requests over the limit receive a 429 with the

internal/server/routes.go

@@ -213,6 +213,18 @@ func (s *Server) setupSourceRoutes() {
 			"/deliveries/{deliveryID}/replay",
 			s.h.HandleDeliveryReplay(),
 		)
+		// Resubmit is the other page action that queues outbound
+		// work: it copies a stored event into a new one and fans
+		// that out to every currently active target. It is
+		// deliberately repeatable, so the rate limit is the only
+		// bound on a held-down button; it gets its own bucket so
+		// that spending it does not also disable replay. POST
+		// only, so the action cannot be taken by a link, a
+		// prefetch or an image tag.
+		r.With(s.mw.ResubmitRateLimit()).Post(
+			"/events/{eventID}/resubmit",
+			s.h.HandleEventResubmit(),
+		)
 		r.Post(
 			"/entrypoints",
 			s.h.HandleEntrypointCreate(),

templates/source_logs.html

@@ -16,6 +16,10 @@
     <div class="{{if .ReplayQueued}}alert-success{{else}}alert-error{{end}}">{{.ReplayMessage}}</div>
     {{end}}
 
+    {{if .ResubmitMessage}}
+    <div class="{{if .ResubmitQueued}}alert-success{{else}}alert-error{{end}}">{{.ResubmitMessage}}</div>
+    {{end}}
+
     <div class="card">
         <div class="divide-y divide-gray-100">
             {{range .Events}}
@@ -25,6 +29,12 @@
                         <span class="badge-info">{{.Method}}</span>
                         <span class="text-sm font-mono text-gray-700">{{.ID}}</span>
                         <span class="text-sm text-gray-500">{{.ContentType}}</span>
+                        {{if .ResubmittedFrom}}
+                        <span class="text-xs text-gray-500" title="This event is a copy of {{.ResubmittedFromID}}">resubmitted copy</span>
+                        {{end}}
+                        {{if .ResubmitCount}}
+                        <span class="text-xs text-gray-500">resubmitted {{.ResubmitCount}} time{{if ne .ResubmitCount 1}}s{{end}}</span>
+                        {{end}}
                     </div>
                     <div class="flex items-center gap-4">
                         {{range .Deliveries}}
@@ -40,6 +50,17 @@
                 </div>
 
                 <div x-show="open" x-cloak class="mt-3 p-3 bg-gray-50 rounded-md">
+                    <div class="mb-3 flex flex-wrap items-center justify-between gap-2">
+                        <div class="text-xs text-gray-500">
+                            {{if .ResubmittedFrom}}Resubmitted from event <span class="font-mono">{{.ResubmittedFromID}}</span>.{{end}}
+                            {{if .ResubmitCount}}Resubmitted as {{.ResubmitCount}} new event{{if ne .ResubmitCount 1}}s{{end}}.{{end}}
+                        </div>
+                        <form method="POST" action="/source/{{$.Webhook.ID}}/events/{{.ID}}/resubmit" class="inline">
+                            <input type="hidden" name="csrf_token" value="{{$.CSRFToken}}">
+                            <input type="hidden" name="page" value="{{$.Page}}">
+                            <button type="submit" class="text-xs text-primary-600 hover:text-primary-700" title="Submit this event again as a new event, to every currently active target">Resubmit</button>
+                        </form>
+                    </div>
                     <pre class="text-xs text-gray-700 overflow-x-auto whitespace-pre-wrap break-all">{{.Body}}</pre>
                     {{if .BodyTruncated}}
                     <p class="mt-2 text-xs text-gray-500">Body truncated for display: showing {{.BodyShownBytes}} of {{.BodyBytes}} bytes. The stored body is unchanged &mdash; <a href="/source/{{$.Webhook.ID}}/logs/{{.ID}}/body" class="text-primary-600 hover:text-primary-700 underline">download the full body</a>.</p>