diff --git a/core/stuck.js b/core/stuck.js
new file mode 100644
index 0000000..fdee254
--- /dev/null
+++ b/core/stuck.js
@@ -0,0 +1,41 @@
+// Files s3d still lists as waiting for Sia whose buffered copy is gone.
+//
+// s3d keeps every not-yet-uploaded object as uploads/<filename> and marks it
+// uploaded by setting sia_object_id. An s3d stopped in the middle of an
+// upload has been seen to delete the copies without recording the upload;
+// every flush after that fails on them ("failed to open upload"). They hold
+// no data any more: not on this computer, never on Sia. Pithos lists them so
+// the user can upload the file again or remove the entry.
+
+import fs from 'node:fs';
+import path from 'node:path';
+
+async function candidates(dataDir, olderThanMs) {
+  const file = path.join(dataDir, 's3d.db');
+  if (!fs.existsSync(file)) return [];
+  const { DatabaseSync } = await import('node:sqlite');
+  const db = new DatabaseSync(file, { readOnly: true });
+  try {
+    const rows = db.prepare(`SELECT b.name AS bucket, u.name AS user, o.name AS key, o.size AS size, o.filename AS filename, o.updated_at AS updated
+      FROM objects o JOIN buckets b ON b.id = o.bucket_id LEFT JOIN users u ON u.id = b.user_id
+      WHERE o.sia_object_id IS NULL AND o.is_latest = 1 AND o.is_delete_marker = 0
+        AND o.filename IS NOT NULL AND o.filename != ''`).all();
+    const uploads = path.join(dataDir, 'uploads');
+    const cutoff = Date.now() - olderThanMs;
+    return rows
+      // updated_at is Unix seconds
+      .filter((r) => { const n = Number(r.updated); const t = Number.isFinite(n) ? (n < 1e12 ? n * 1000 : n) : Date.parse(r.updated); return !Number.isFinite(t) || t < cutoff; })
+      .filter((r) => !fs.existsSync(path.join(uploads, path.basename(String(r.filename)))))
+      .map((r) => ({ bucket: r.bucket, user: r.user, key: r.key, size: Number(r.size), filename: String(r.filename) }));
+  } finally { db.close(); }
+}
+
+// Only entries missing twice, a moment apart: s3d removes a copy just before
+// it records the upload, and a list taken in between would be wrong.
+export async function stuckUploads(dataDir, { olderThanMs = 120_000, settleMs = 2000 } = {}) {
+  const first = await candidates(dataDir, olderThanMs);
+  if (!first.length) return [];
+  await new Promise((r) => setTimeout(r, settleMs));
+  const again = new Set((await candidates(dataDir, olderThanMs)).map((r) => `${r.bucket}\n${r.key}`));
+  return first.filter((r) => again.has(`${r.bucket}\n${r.key}`));
+}
diff --git a/test/stuck.test.js b/test/stuck.test.js
new file mode 100644
index 0000000..031506c
--- /dev/null
+++ b/test/stuck.test.js
@@ -0,0 +1,35 @@
+// Waiting files whose buffered copy is gone are listed; uploaded files,
+// files with their copy, and very recent changes are not.
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import { DatabaseSync } from 'node:sqlite';
+import { stuckUploads } from '../core/stuck.js';
+
+test('stuck uploads: missing copy, still waiting, not brand new', async (t) => {
+  const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'pithos-stuck-'));
+  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  fs.mkdirSync(path.join(dir, 'uploads'));
+  const db = new DatabaseSync(path.join(dir, 's3d.db'));
+  db.exec(`CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT);
+    CREATE TABLE buckets (id INTEGER PRIMARY KEY, name TEXT, user_id INTEGER);
+    CREATE TABLE objects (bucket_id INTEGER, name TEXT, is_latest INTEGER, is_delete_marker INTEGER, size INTEGER, updated_at INTEGER, filename TEXT, sia_object_id BLOB);
+    INSERT INTO users VALUES (1, 'game.x');
+    INSERT INTO buckets VALUES (1, 'house-music', 1);`);
+  const old = Math.floor(Date.now() / 1000) - 3600;
+  const now = Math.floor(Date.now() / 1000);
+  const add = db.prepare('INSERT INTO objects VALUES (1, ?, 1, 0, ?, ?, ?, ?)');
+  add.run('lost.mp3', 5000, old, 'aaaa.obj', null);          // stuck
+  add.run('waiting.mp3', 4000, old, 'bbbb.obj', null);       // copy present
+  add.run('uploaded.mp3', 3000, old, null, Buffer.from([1])); // on Sia
+  add.run('just-now.mp3', 2000, now, 'cccc.obj', null);      // too recent to judge
+  db.prepare('INSERT INTO objects VALUES (1, ?, 0, 0, ?, ?, ?, NULL)').run('old-version.mp3', 1, old, 'dddd.obj'); // not latest
+  db.close();
+  fs.writeFileSync(path.join(dir, 'uploads', 'bbbb.obj'), 'x');
+
+  const items = await stuckUploads(dir, { settleMs: 10 });
+  assert.deepEqual(items, [{ bucket: 'house-music', user: 'game.x', key: 'lost.mp3', size: 5000, filename: 'aaaa.obj' }]);
+  assert.deepEqual(await stuckUploads(path.join(dir, 'nope'), { settleMs: 10 }), []);
+});
diff --git a/ui/app.css b/ui/app.css
index 28de4f6..f951425 100644
--- a/ui/app.css
+++ b/ui/app.css
@@ -475,3 +475,9 @@ a.brand:hover > span:first-of-type { color: var(--accent); }
 .link-card .row { gap: 6px; flex-wrap: wrap; }
 .link-make { gap: 10px; align-items: center; flex-wrap: wrap; }
 .link-card a.btn { text-decoration: none; }
+
+/* Waiting files that lost their copy (stuck uploads) */
+.banner.stuck .stack { gap: 8px; width: 100%; }
+.stuck-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 6px; }
+.stuck-list li { display: flex; gap: 8px; align-items: center; justify-content: space-between; flex-wrap: wrap; }
+.stuck-name { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; flex: 1 1 220px; }
diff --git a/ui/app.js b/ui/app.js
index 777b26f..ea91c6a 100644
--- a/ui/app.js
+++ b/ui/app.js
@@ -294,7 +294,7 @@ function overview(main) {
   main.append(
     h('div', { class: 'page-head' }, h('div', {}, h('h1', {}, 'Overview'), h('p', { class: 'muted' }, 'Your s3d gateway and its upload pipeline to Sia.'))),
     banners,
-    pendingBanner(),
+    stuckBanner(), pendingBanner(),
     h('div', { class: 'grid two' }, daemonCard, statsCard),
   );
 
@@ -1424,6 +1424,60 @@ function siaAccountBlock(a, onRefresh) {
 // "N files are waiting to upload to Sia" with Upload now. s3d holds small
 // uploads until about 40 MB has built up; until then they exist only on this
 // computer, which is easy to miss.
+// Files s3d still lists as waiting whose copy on this computer is gone (an
+// upload was cut off): each can be uploaded again from the original, or removed.
+function stuckBanner() {
+  const el = h('div', { hidden: true });
+  async function paint() {
+    let items = [];
+    try { items = (await api('GET', '/api/uploads/stuck')).items || []; } catch {}
+    if (!items.length) { el.hidden = true; return; }
+    const remove = async (i) => {
+      try { await api('POST', '/api/uploads/stuck/remove', { bucket: i.bucket, key: i.key }); } catch (e) { fail(e); }
+    };
+    const again = (i) => {
+      const input = h('input', { type: 'file', hidden: true, onchange: async () => {
+        const file = input.files[0];
+        if (!file) return;
+        const path = `/api/s3/${encodeURIComponent(i.user)}/buckets/${encodeURIComponent(i.bucket)}/object?key=${encodeURIComponent(i.key)}`;
+        try {
+          if (bridge) {
+            const r = await bridge.invoke('upload', { path, bytes: await file.arrayBuffer(), type: file.type });
+            if (r.status >= 300) throw new Error(r.data?.error || `HTTP ${r.status}`);
+          } else {
+            const r = await fetch(path, { method: 'PUT', headers: { 'x-pithos': '1', ...(file.type ? { 'content-type': file.type } : {}) }, body: file });
+            if (!r.ok) throw new Error((await r.json().catch(() => ({}))).error || `HTTP ${r.status}`);
+          }
+          toast(`Uploaded ${i.key.split('/').pop()} again`);
+          paint();
+        } catch (e) { fail(e); }
+      } });
+      document.body.append(input);
+      input.click();
+      setTimeout(() => input.remove(), 60_000);
+    };
+    put(el, h('div', { class: 'banner warn stuck' },
+      h('div', { class: 'stack' },
+        h('span', {}, h('strong', {}, `${items.length} file${items.length === 1 ? '' : 's'} lost ${items.length === 1 ? 'its' : 'their'} copy before reaching Sia. `),
+          h('span', { class: 'small' }, items.length === 1
+            ? 'An upload was cut off, and it was removed from this computer before it reached Sia. Upload it again from the original, or remove it; until then Upload now stops on it.'
+            : 'An upload was cut off, and they were removed from this computer before they reached Sia. Upload each one again from the original, or remove it; until then Upload now stops on them.')),
+        h('ul', { class: 'stuck-list' }, items.map((i) => h('li', {},
+          h('span', { class: 'stuck-name', title: `${i.bucket}/${i.key}` }, h('span', { class: 'muted' }, `${i.bucket} / `), i.key, h('span', { class: 'muted small' }, ` · ${fmtBytes(i.size)}`)),
+          h('span', { class: 'row' },
+            h('button', { class: 'btn small', onclick: () => again(i) }, 'Upload again…'),
+            h('button', { class: 'btn small danger', onclick: async () => { await remove(i); paint(); } }, 'Remove'))))),
+        items.length > 1 && h('div', {}, h('button', { class: 'btn small danger', onclick: async () => {
+          if (!(await confirmModal(`Remove ${items.length} entries?`, 'Their files are already gone from this computer and never reached Sia; this only removes the names.', 'Remove all'))) return;
+          for (const i of items) await remove(i);
+          paint();
+        } }, 'Remove all')))));
+    el.hidden = false;
+  }
+  paint();
+  return el;
+}
+
 function pendingBanner() {
   const el = h('div', { hidden: true });
   const st = daemonState();
@@ -1494,7 +1548,7 @@ async function bucketList(head, body, user, userSel) {
     h('div', { class: 'row' }, userPicker(userSel), h('button', { class: 'btn primary', onclick: create }, 'New drive')));
   const card = h('div', { class: 'card' }, h('p', { class: 'muted' }, 'Loading…'));
   const bar = h('div', { class: 'view-bar' });
-  put(body, pendingBanner(), bar, card);
+  put(body, stuckBanner(), pendingBanner(), bar, card);
   const base = `/api/s3/${encodeURIComponent(user)}/buckets`;
   let mode = viewMode('drives', 'icons');
   let list = [];