README.md

@@ -1050,7 +1050,8 @@ Archive databases are the one exception the service is built for: the
 archive writer closes and reopens its handle around writes (debounced
 to at most one reopen per second), so an operator can move an
 `archive-….db` away for offline retention while the service runs,
-and it is recreated on the next write. See
+and it is recreated on the next write. The webhook page names each
+`database` target's archive file. See
 [Database Architecture](#database-architecture). That is a
 move-the-file-away workflow, not a substitute for the backup procedures
 above.
@@ -2033,6 +2034,14 @@ Because each `database` target has its own archive file, a target's
 webhook with different expiries keep two archives, each pruned on its
 own schedule.
 
+The webhook page shows, for each `database` target, its archive file's
+name, its size on disk and when it was last written. The size counts
+the `.db` and its `-wal` together, and the last write is the later of
+their two modification times, since a write lands in the `-wal` first.
+Both are read from the files' metadata; the archive is never opened.
+Before the first write, and after the file has been moved away, the page
+shows `not created yet` beside the name.
+
 Each `database` target on the webhook page has a **Download** button,
 which returns its archive as one gzipped JSON file,
 `archive-{webhook_name}-{target_name}-{YYYYMMDDTHHMMSSZ}.json.gz`, the

internal/delivery/target_database_archive.go

@@ -515,6 +515,47 @@ func (w *archiveWriter) prune(expiry time.Duration) {
 	}
 }
 
+// ArchiveFileInfo is what the metadata of a database target's archive
+// file says about it.
+type ArchiveFileInfo struct {
+	// Size is the bytes on disk of the file and its -wal together.
+	Size int64
+
+	// Written is when the file or its -wal was last modified, whichever
+	// is later: a write lands in the -wal first.
+	Written time.Time
+}
+
+// StatArchive reads the metadata of the archive file at path and of
+// its -wal, without opening the archive. With no file at path, which is
+// so before the first write and after the operator moved it away, the
+// error wraps fs.ErrNotExist.
+func StatArchive(path string) (ArchiveFileInfo, error) {
+	file, err := os.Stat(path)
+	if err != nil {
+		return ArchiveFileInfo{}, err
+	}
+
+	info := ArchiveFileInfo{Size: file.Size(), Written: file.ModTime()}
+
+	wal, err := os.Stat(path + "-wal")
+	if errors.Is(err, fs.ErrNotExist) {
+		return info, nil
+	}
+
+	if err != nil {
+		return ArchiveFileInfo{}, err
+	}
+
+	info.Size += wal.Size()
+
+	if wal.ModTime().After(info.Written) {
+		info.Written = wal.ModTime()
+	}
+
+	return info, nil
+}
+
 // fileExists reports whether a path currently exists.
 func fileExists(path string) bool {
 	_, err := os.Stat(path)

internal/delivery/target_database_test.go

@@ -3,6 +3,7 @@ package delivery_test
 import (
 	"database/sql"
 	"fmt"
+	"io/fs"
 	"log/slog"
 	"os"
 	"path/filepath"
@@ -183,6 +184,49 @@ func TestArchiveWriter_RecreatesAfterRemoval(
 	assert.Equal(t, "b", got[0].EventID)
 }
 
+// TestStatArchive proves StatArchive finds no file before the first
+// write; after a write still held in the -wal, counts the -wal in the
+// size and takes its later time as the last write; and finds no file
+// again once the file has been moved away.
+func TestStatArchive(t *testing.T) {
+	t.Parallel()
+
+	path := filepath.Join(t.TempDir(), "archive-wh.db")
+
+	_, err := delivery.StatArchive(path)
+	require.ErrorIs(t, err, fs.ErrNotExist)
+
+	// With the clock stopped, the reopen debounce never passes, so
+	// the handle stays open after the write.
+	stopped := time.Now()
+	w := delivery.NewExportArchiveWriter(path, archiveTestLogger(), 0)
+	w.SetNow(func() time.Time { return stopped })
+
+	require.NoError(t, w.Write(delivery.ExportArchivedEvent{EventID: "a"}, 0))
+
+	written := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
+	earlier := written.Add(-time.Hour)
+	require.NoError(t, os.Chtimes(path, earlier, earlier))
+	require.NoError(t, os.Chtimes(path+"-wal", written, written))
+
+	file, err := os.Stat(path)
+	require.NoError(t, err)
+
+	wal, err := os.Stat(path + "-wal")
+	require.NoError(t, err)
+	require.Positive(t, wal.Size())
+
+	got, err := delivery.StatArchive(path)
+	require.NoError(t, err)
+	assert.Equal(t, file.Size()+wal.Size(), got.Size)
+	assert.True(t, written.Equal(got.Written), got.Written)
+
+	removeArchiveFiles(t, path)
+
+	_, err = delivery.StatArchive(path)
+	require.ErrorIs(t, err, fs.ErrNotExist)
+}
+
 func TestArchiveWriter_ReopenDebounce(t *testing.T) {
 	t.Parallel()
 

internal/handlers/source_management.go

@@ -521,7 +521,7 @@ func (h *Handlers) renderSourceDetail(
 		// target's stored config blob holds a credential, and it
 		// must never reach a template.
 		"Entrypoints": NewEntrypointViews(entrypoints),
-		"Targets":     delivery.NewTargetViews(targets),
+		"Targets":     h.targetRows(&webhook, targets),
 		"Events":      events,
 		"BaseURL":     baseURL,
 		"Stats":       h.loadWebhookStats(webhook.ID, entrypoints, targets),

internal/handlers/target_list.go

@@ -0,0 +1,90 @@
+package handlers
+
+import (
+	"errors"
+	"io/fs"
+	"path/filepath"
+	"time"
+
+	"github.com/dustin/go-humanize"
+	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/delivery"
+)
+
+// TargetRowView is one row of the target list on a webhook's page.
+type TargetRowView struct {
+	delivery.TargetView
+
+	// Archive is a database target's archive file, and nil for a target
+	// of any other type.
+	Archive *ArchiveFileView
+}
+
+// ArchiveFileView is what a database target's row shows about its
+// archive file.
+type ArchiveFileView struct {
+	Name string
+
+	// Note stands in for the size and the last write when there are
+	// none to show, and is empty when there are.
+	Note string
+
+	// Size is the size on disk. Written is how long ago the file was
+	// last written, and WrittenUTC the full time the page shows on
+	// hover.
+	Size       string
+	Written    string
+	WrittenUTC string
+}
+
+// targetRows projects a webhook's targets for the target list on its
+// page.
+func (h *Handlers) targetRows(
+	webhook *database.Webhook, targets []database.Target,
+) []TargetRowView {
+	views := delivery.NewTargetViews(targets)
+	rows := make([]TargetRowView, len(views))
+
+	// NewTargetViews returns one view per target, in order.
+	for i := range views {
+		rows[i].TargetView = views[i]
+
+		if targets[i].Type == database.TargetTypeDatabase {
+			rows[i].Archive = h.archiveFileView(webhook, &targets[i])
+		}
+	}
+
+	return rows
+}
+
+// archiveFileView describes a database target's archive file from the
+// file's metadata alone; the archive is never opened. The file is found
+// by the name the archive writer uses, so it follows a rename of the
+// webhook or the target.
+func (h *Handlers) archiveFileView(
+	webhook *database.Webhook, target *database.Target,
+) *ArchiveFileView {
+	path := delivery.ArchivePath(h.dbMgr, webhook, target)
+	view := &ArchiveFileView{Name: filepath.Base(path)}
+
+	file, err := delivery.StatArchive(path)
+
+	switch {
+	case errors.Is(err, fs.ErrNotExist):
+		view.Note = "not created yet"
+	case err != nil:
+		h.log.Error(
+			"failed to read archive file metadata",
+			"target_id", target.ID,
+			"error", err,
+		)
+
+		view.Note = "could not be read"
+	default:
+		view.Size = humanize.Bytes(uint64(file.Size)) //nolint:gosec // never negative
+		view.Written = humanize.Time(file.Written)
+		view.WrittenUTC = file.Written.UTC().Format(time.DateTime) + " UTC"
+	}
+
+	return view
+}

internal/handlers/target_list_test.go

@@ -0,0 +1,71 @@
+package handlers_test
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/delivery"
+	"sneak.berlin/go/webhooker/internal/handlers"
+	"sneak.berlin/go/webhooker/internal/session"
+)
+
+// TestHandleSourceDetail_ShowsArchiveFile proves a database target's
+// row names its archive file and says "not created yet" before the
+// first write, adds the file's size and last write once it has one row,
+// and says "not created yet" again once the file has been moved away.
+// A target of another type shows no archive file.
+func TestHandleSourceDetail_ShowsArchiveFile(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)
+	archive := seedTarget(t, db, wh.ID, database.TargetTypeDatabase)
+	seedTarget(t, db, wh.ID, database.TargetTypeLog)
+
+	path := delivery.ArchivePath(dbMgr, wh, archive)
+
+	body := renderSourceDetailPage(t, h, sess, wh.ID)
+	assert.Equal(t, 1, strings.Count(body, "Archive File:"))
+	assert.Contains(t, body, filepath.Base(path))
+	assert.Contains(t, body, "not created yet")
+	assert.NotContains(t, body, "Archive Size:")
+
+	seedArchive(t, path, 1, 100)
+
+	file, err := os.Stat(path)
+	require.NoError(t, err)
+
+	body = renderSourceDetailPage(t, h, sess, wh.ID)
+	assert.Contains(t, body, filepath.Base(path))
+	assert.NotContains(t, body, "not created yet")
+	assert.Regexp(t,
+		`Archive Size:</span>\s*<span>[1-9][0-9.]* [kM]?B</span>`, body,
+	)
+	assert.Contains(t, body,
+		`title="`+file.ModTime().UTC().Format(time.DateTime)+` UTC"`,
+	)
+
+	require.NoError(t, os.Rename(path, filepath.Join(t.TempDir(), "moved.db")))
+
+	body = renderSourceDetailPage(t, h, sess, wh.ID)
+	assert.Contains(t, body, filepath.Base(path))
+	assert.Contains(t, body, "not created yet")
+	assert.NotContains(t, body, "Archive Size:")
+}

templates/source_detail.html

@@ -179,6 +179,23 @@
                         <span>{{.Value}}</span>
                     </div>
                     {{end}}
+                    {{with .Archive}}
+                    <div class="text-xs text-gray-500 mt-1">
+                        <span class="font-medium text-gray-700">Archive File:</span>
+                        <span class="break-all">{{.Name}}</span>
+                        {{with .Note}}<span>({{.}})</span>{{end}}
+                    </div>
+                    {{if .Size}}
+                    <div class="text-xs text-gray-500 mt-1">
+                        <span class="font-medium text-gray-700">Archive Size:</span>
+                        <span>{{.Size}}</span>
+                    </div>
+                    <div class="text-xs text-gray-500 mt-1">
+                        <span class="font-medium text-gray-700">Last Written:</span>
+                        <span title="{{.WrittenUTC}}">{{.Written}}</span>
+                    </div>
+                    {{end}}
+                    {{end}}
                 </div>
                 {{else}}
                 <div class="p-4 text-sm text-gray-500">No targets configured.</div>