diff --git a/app/Modules/Files/Http/Controllers/FileThumbnailController.php b/app/Modules/Files/Http/Controllers/FileThumbnailController.php
index fbaf2dbe..3336d255 100644
--- a/app/Modules/Files/Http/Controllers/FileThumbnailController.php
+++ b/app/Modules/Files/Http/Controllers/FileThumbnailController.php
@@ -6,11 +6,11 @@ namespace App\Modules\Files\Http\Controllers;
 
 use App\Http\Controllers\Controller;
 use App\Modules\Audit\Action;
-use App\Modules\Audit\ActivityLogger;
 use App\Modules\Files\Access\DownloadAllowance;
 use App\Modules\Files\Delivery\StoredFileResponse;
 use App\Modules\Files\Models\File;
 use App\Modules\Files\Preview\PreviewKind;
+use App\Modules\Files\Preview\PreviewLog;
 use App\Modules\Files\Thumbnails\Events\ResolvingImageRendering;
 use App\Modules\Files\Thumbnails\ImageAudience;
 use App\Modules\Files\Thumbnails\ImageRendition;
@@ -22,7 +22,6 @@ use App\Support\ContentDisposition;
 use Illuminate\Http\RedirectResponse;
 use Illuminate\Http\Request;
 use Illuminate\Http\Response;
-use Illuminate\Support\Facades\Cache;
 use Illuminate\Support\Facades\Event;
 use Illuminate\Support\Facades\Gate;
 use Illuminate\Support\Facades\Storage;
@@ -72,7 +71,7 @@ class FileThumbnailController extends Controller
 {
     public function __construct(
         private readonly ThumbnailGenerator $thumbnails,
-        private readonly ActivityLogger $activity,
+        private readonly PreviewLog $previews,
         private readonly DownloadAllowance $allowance,
         private readonly StoredFileResponse $bytes,
         private readonly LocalSourceFile $source,
@@ -144,7 +143,10 @@ class FileThumbnailController extends Controller
         // file.
         abort_unless($this->allowance->allows($file, $request->user()), 403);
 
-        $this->logPreview($file, $request);
+        // Debounced, because a browser turns one video into dozens of
+        // Range requests — see PreviewLog, which the anonymous twin in
+        // PublicGroupsController::preview shares.
+        $this->previews->record(Action::FilePreviewed, $file, $request->user());
 
         if ($kind === PreviewKind::Image) {
             $audience = ImageAudience::forViewer($request->user());
@@ -164,29 +166,6 @@ class FileThumbnailController extends Controller
         return $this->bytes->inline($file);
     }
 
-    /**
-     * One log row per viewer per file per five minutes.
-     *
-     * Watching a video is a single deliberate act that the browser turns
-     * into dozens of Range requests against this route, and each one
-     * arrives here indistinguishable from someone clicking preview again.
-     * Cache::add is the whole mechanism: it writes only if the key is
-     * absent, so the first request through the window logs and the rest
-     * are silent, without a read-then-write race between two of them.
-     *
-     * Keyed by viewer, so one client's playback never suppresses another
-     * person's preview of the same file. Anonymous viewers do not reach
-     * this route at all — see PublicGroupsController::preview.
-     */
-    private function logPreview(File $file, Request $request): void
-    {
-        $key = 'file-preview-logged:'.$file->id.':'.($request->user()->id ?? 'guest');
-
-        if (Cache::add($key, true, now()->addMinutes(5))) {
-            $this->activity->log(Action::FilePreviewed, subject: $file);
-        }
-    }
-
     /**
      * The cached rendition's path on the local disk, generating it first
      * if this is the first time anyone has asked for it. Null only when
diff --git a/app/Modules/Files/Preview/PreviewLog.php b/app/Modules/Files/Preview/PreviewLog.php
new file mode 100644
index 00000000..4c1d4083
--- /dev/null
+++ b/app/Modules/Files/Preview/PreviewLog.php
@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Modules\Files\Preview;
+
+use App\Models\User;
+use App\Modules\Audit\Action;
+use App\Modules\Audit\ActivityLogger;
+use App\Modules\Files\Models\File;
+use Illuminate\Support\Facades\Cache;
+
+/**
+ * One log row per viewer per file per five minutes, for both preview
+ * routes — FileThumbnailController::preview (signed in) and
+ * PublicGroupsController::preview (anonymous).
+ *
+ * Watching a video is a single deliberate act that the browser turns into
+ * dozens of Range requests, each arriving indistinguishable from someone
+ * clicking preview again. Cache::add is the whole mechanism: it writes
+ * only if the key is absent, so the first request through the window logs
+ * and the rest are silent, without a read-then-write race between two of
+ * them.
+ *
+ * Keyed by viewer, so one person's playback never suppresses another's
+ * view of the same file. An anonymous visitor has no account to key on,
+ * so the request IP stands in — the same substitute the API's rate
+ * limiter makes for an unauthenticated caller. It is a cache key with a
+ * five-minute life and never reaches the log, which keeps its own
+ * decision about recording an IP (see ActivityLogger::shouldRecordIp and
+ * Setting::DownloadIpLogging).
+ *
+ * Shared rather than restated, because the window is the rule: two copies
+ * of "five minutes" are two things to change and one to forget.
+ */
+class PreviewLog
+{
+    private const WINDOW_MINUTES = 5;
+
+    public function __construct(
+        private readonly ActivityLogger $activity,
+    ) {}
+
+    public function record(Action $action, File $file, ?User $viewer): void
+    {
+        $viewerKey = $viewer !== null ? (string) $viewer->id : 'ip:'.request()->ip();
+
+        if (Cache::add('file-preview-logged:'.$file->id.':'.$viewerKey, true, now()->addMinutes(self::WINDOW_MINUTES))) {
+            $this->activity->log($action, subject: $file);
+        }
+    }
+}
diff --git a/app/Modules/Groups/Http/Controllers/PublicGroupsController.php b/app/Modules/Groups/Http/Controllers/PublicGroupsController.php
index f4e292b2..42483f16 100644
--- a/app/Modules/Groups/Http/Controllers/PublicGroupsController.php
+++ b/app/Modules/Groups/Http/Controllers/PublicGroupsController.php
@@ -14,6 +14,7 @@ use App\Modules\Files\Models\Category;
 use App\Modules\Files\Models\File;
 use App\Modules\Files\Models\Folder;
 use App\Modules\Files\Preview\PreviewKind;
+use App\Modules\Files\Preview\PreviewLog;
 use App\Modules\Files\Thumbnails\ImageAudience;
 use App\Modules\Files\Thumbnails\ImageRendition;
 use App\Modules\Files\Thumbnails\LocalSourceFile;
@@ -77,6 +78,7 @@ class PublicGroupsController extends Controller
     public function __construct(
         private readonly Settings $settings,
         private readonly ActivityLogger $activity,
+        private readonly PreviewLog $previews,
         private readonly DownloadAllowance $allowance,
         private readonly ThumbnailGenerator $thumbnails,
         private readonly PublicThemeRegistry $themes,
@@ -298,7 +300,11 @@ class PublicGroupsController extends Controller
         // nothing.
         abort_unless($this->allowance->allows($file, null), 403);
 
-        $this->activity->log(Action::PublicFilePreviewed, subject: $file);
+        // Debounced exactly as the signed-in twin is, and for the same
+        // reason: a single visitor watching one video arrives here dozens
+        // of times. Without a viewer to key on, PreviewLog keys on the
+        // request IP.
+        $this->previews->record(Action::PublicFilePreviewed, $file, null);
 
         return $this->bytes->inline($file);
     }
diff --git a/tests/Feature/Groups/PublicFilePreviewTest.php b/tests/Feature/Groups/PublicFilePreviewTest.php
index a63020b2..b28142d7 100644
--- a/tests/Feature/Groups/PublicFilePreviewTest.php
+++ b/tests/Feature/Groups/PublicFilePreviewTest.php
@@ -45,6 +45,45 @@ test('a visitor can preview a public file, and it is logged as a public preview'
         ->and(ActivityLog::query()->where('action', Action::PublicFileDownloaded)->where('subject_id', $file->id)->exists())->toBeFalse();
 });
 
+// The same deliberate act, and the same long tail of Range requests a
+// browser makes of it. The signed-in twin has debounced this since it was
+// written; the anonymous one wrote a row per request.
+test('replaying a public preview logs it once, not once per request', function () {
+    $file = publicListingFile();
+
+    foreach (range(1, 5) as $ignored) {
+        $this->get(route('public.preview', ['public', $file->slug]))->assertOk();
+    }
+
+    expect(ActivityLog::query()->where('action', Action::PublicFilePreviewed)->where('subject_id', $file->id)->count())
+        ->toBe(1);
+});
+
+test('two visitors of the same file are each logged', function () {
+    // Keyed by viewer, and an anonymous visitor's stand-in is their IP —
+    // so one visitor's playback cannot swallow the record of somebody else
+    // looking at the same file.
+    $file = publicListingFile();
+
+    $this->get(route('public.preview', ['public', $file->slug]))->assertOk();
+
+    $this->withServerVariables(['REMOTE_ADDR' => '198.51.100.7'])
+        ->get(route('public.preview', ['public', $file->slug]))->assertOk();
+
+    expect(ActivityLog::query()->where('action', Action::PublicFilePreviewed)->where('subject_id', $file->id)->count())
+        ->toBe(2);
+});
+
+test('the window is per file, so a second public file is still logged', function () {
+    $first = publicListingFile();
+    $second = publicListingFile(['name' => 'second', 'slug' => 'second-report']);
+
+    $this->get(route('public.preview', ['public', $first->slug]))->assertOk();
+    $this->get(route('public.preview', ['public', $second->slug]))->assertOk();
+
+    expect(ActivityLog::query()->where('action', Action::PublicFilePreviewed)->count())->toBe(2);
+});
+
 test('a file that is not public, or has expired, has no preview', function () {
     $private = publicListingFile(['public' => false]);
     $expired = publicListingFile(['expires_at' => now()->subDay()]);