diff --git a/dashboard/web/src/PlatformPicker.jsx b/dashboard/web/src/PlatformPicker.jsx
index 2218753..28eafd5 100644
--- a/dashboard/web/src/PlatformPicker.jsx
+++ b/dashboard/web/src/PlatformPicker.jsx
@@ -49,12 +49,25 @@ function TargetSelect({ conn, value, onChange, id }) {
 
 const TT_PRIVACY = { PUBLIC_TO_EVERYONE: "Everyone", MUTUAL_FOLLOW_FRIENDS: "Friends", FOLLOWER_OF_CREATOR: "Followers", SELF_ONLY: "Only me" };
 
+const mediaSrc = (m) => (/^https?:/.test(m) ? m : `/api/schedule/media?path=${encodeURIComponent(m)}`);
+const isVideoFile = (m) => /\.(mp4|mov|m4v|webm)$/i.test(String(m).split("?")[0]);
+const fmtSecs = (s) => `${Math.floor(s / 60)} min${s % 60 ? ` ${Math.round(s % 60)} s` : ""}`;
+
 /** TikTok's post screen, following its Content Posting API guidelines (creator info, no default audience, disclosure, consent). */
-function TikTokFields({ platform, type, options, setOption, caption }) {
+function TikTokFields({ platform, type, options, setOption, caption, media = [] }) {
   const [creator, setCreator] = useState(null);
   const [error, setError] = useState(null);
+  const [videoSecs, setVideoSecs] = useState(null);
   useEffect(() => { api(`/api/connections/${platform.conn.id}/creator-info`).then((r) => setCreator(r.creator)).catch(setError); }, [platform.conn.id]);
   const video = type === "REELS";
+  const firstVideo = media.find(isVideoFile);
+  useEffect(() => { setVideoSecs(null); }, [firstVideo]);
+  const tooLong = Boolean(video && creator?.maxVideoSeconds && videoSecs && videoSecs > creator.maxVideoSeconds);
+  // Problems that must stop the post being saved (read by selectionFor through the _problem option).
+  const problem = error ? `TikTok says this account can't post right now: ${error.message}`
+    : tooLong ? `This video is ${fmtSecs(videoSecs)}; this TikTok account can post videos up to ${fmtSecs(creator.maxVideoSeconds)}. Trim it or untick TikTok.`
+    : undefined;
+  useEffect(() => { if ((options._problem || undefined) !== problem) setOption("_problem", problem); }, [problem]); // eslint-disable-line react-hooks/exhaustive-deps
   const branded = Boolean(options.discloseCommercial && options.brandedContent);
   const organic = Boolean(options.discloseCommercial && options.brandOrganic);
   const check = (key, label, disabled, note) => (
@@ -77,7 +90,18 @@ function TikTokFields({ platform, type, options, setOption, caption }) {
           <span className="font-medium">{creator.nickname}</span>{creator.username && <span className="text-muted">@{creator.username}</span>}
         </>}
       </div>
-      {error && <div className="text-[12.5px] text-bad">Couldn't load this TikTok account's settings: {error.message}. Reconnect TikTok on the Connections page.</div>}
+      {error && <div className="text-[12.5px] text-bad">{problem} If it says the sign-in expired, reconnect TikTok on the Connections page.</div>}
+      {media.length > 0 && (
+        <div>
+          <div className="text-[12px] text-muted mb-1.5">Preview of what will be posted</div>
+          <div className="flex gap-2 overflow-x-auto">
+            {media.map((m) => isVideoFile(m)
+              ? <video key={m} src={mediaSrc(m)} className="h-40 rounded-md bg-black" controls muted preload="metadata" onLoadedMetadata={(e) => { if (m === firstVideo) setVideoSecs(e.currentTarget.duration); }} />
+              : <img key={m} src={mediaSrc(m)} alt="" className="h-40 rounded-md object-cover" />)}
+          </div>
+          {tooLong && <div className="text-[12.5px] text-bad mt-1.5">{problem}</div>}
+        </div>
+      )}
       {!creator && !error && <div className="text-[12.5px] text-muted">Loading the account's TikTok settings…</div>}
       {creator && (
         <Field label="How to post">
@@ -140,8 +164,8 @@ function TikTokFields({ platform, type, options, setOption, caption }) {
   );
 }
 
-function PlatformFields({ platform, type, options, setOption, caption }) {
-  if (platform.id === "tiktok") return <TikTokFields platform={platform} type={type} options={options} setOption={setOption} caption={caption} />;
+function PlatformFields({ platform, type, options, setOption, caption, media }) {
+  if (platform.id === "tiktok") return <TikTokFields platform={platform} type={type} options={options} setOption={setOption} caption={caption} media={media} />;
   const fields = platform.fields.filter((f) => !f.onlyFor || f.onlyFor.includes(type));
   const own = options.caption;
   const limit = platform.limits?.caption;
@@ -185,7 +209,7 @@ function PlatformFields({ platform, type, options, setOption, caption }) {
  * value: { platforms: string[], options: { [platform]: {...} } }, onChange(next)
  * type: the post format (IMAGE, REELS, CAROUSEL, STORY, TEXT)
  */
-export default function PlatformPicker({ client, type, caption, value, onChange, available }) {
+export default function PlatformPicker({ client, type, caption, value, onChange, available, media = [] }) {
   const { loading, list } = available;
   const byId = useMemo(() => Object.fromEntries(list.map((p) => [p.id, p])), [list]);
   const toggle = (id) => onChange({ ...value, platforms: value.platforms.includes(id) ? value.platforms.filter((x) => x !== id) : [...value.platforms, id] });
@@ -207,7 +231,7 @@ export default function PlatformPicker({ client, type, caption, value, onChange,
         })}
       </div>
       {value.platforms.filter((id) => byId[id] && !byId[id].meta && byId[id].formats.includes(type)).map((id) => (
-        <PlatformFields key={id} platform={byId[id]} type={type} caption={caption} options={value.options[id] || {}} setOption={setOption(id)} />
+        <PlatformFields key={id} platform={byId[id]} type={type} caption={caption} media={media} options={value.options[id] || {}} setOption={setOption(id)} />
       ))}
     </div>
   );
@@ -217,6 +241,9 @@ export default function PlatformPicker({ client, type, caption, value, onChange,
 export function selectionFor(value, available, type) {
   const ok = new Set(available.list.filter((p) => p.formats.includes(type)).map((p) => p.id));
   const platforms = value.platforms.filter((p) => ok.has(p));
-  const options = Object.fromEntries(platforms.filter((p) => value.options[p]).map((p) => [p, value.options[p]]));
-  return { platforms, options };
+  const problems = platforms.map((p) => value.options[p]?._problem).filter(Boolean);
+  // Keys starting with "_" are screen-only state; don't send them.
+  const clean = (o) => Object.fromEntries(Object.entries(o).filter(([k]) => !k.startsWith("_")));
+  const options = Object.fromEntries(platforms.filter((p) => value.options[p]).map((p) => [p, clean(value.options[p])]));
+  return { platforms, options, problems };
 }
diff --git a/dashboard/web/src/pages/Library.jsx b/dashboard/web/src/pages/Library.jsx
index 6ad97db..2cdc408 100644
--- a/dashboard/web/src/pages/Library.jsx
+++ b/dashboard/web/src/pages/Library.jsx
@@ -229,6 +229,7 @@ function ScheduleDialog({ item, clientName, onClose, onDone }) {
   const submit = async () => {
     setBusy(true); setError(null);
     try {
+      if (chosen.problems.length) throw new Error(chosen.problems[0]);
       await api(`/api/library/${item.id}/schedule`, { method: "POST", body: { platforms: chosen.platforms, options: chosen.options, localTime: `${f.date} ${f.time}`, caption: f.caption, fbCaption: f.fbCaption || undefined, collaborators: f.collaborators.split(/[\s,]+/).map((x) => x.replace(/^@/, "")).filter(Boolean) } });
       onDone();
     } catch (e) { setError(e); setBusy(false); }
@@ -242,7 +243,7 @@ function ScheduleDialog({ item, clientName, onClose, onDone }) {
         </Field>
       </div>
       <Field label="Caption"><textarea className="input h-28" value={f.caption} onChange={(e) => set("caption", e.target.value)} /></Field>
-      <Field label="Post to"><PlatformPicker client={item.client} type={item.format} caption={f.caption} value={sel} onChange={setSel} available={available} /></Field>
+      <Field label="Post to"><PlatformPicker client={item.client} type={item.format} caption={f.caption} value={sel} onChange={setSel} available={available} media={item.files} /></Field>
       {sel.platforms.includes("facebook") && <Field label="Facebook caption (optional)"><textarea className="input h-16" value={f.fbCaption} onChange={(e) => set("fbCaption", e.target.value)} /></Field>}
       {sel.platforms.includes("instagram") && item.format !== "STORY" && <Field label="Collab invites (optional)"><input className="input" placeholder="@username" value={f.collaborators} onChange={(e) => set("collaborators", e.target.value)} /></Field>}
       <ErrorNote error={error} />
diff --git a/dashboard/web/src/pages/Publishing.jsx b/dashboard/web/src/pages/Publishing.jsx
index 477e927..c40b699 100644
--- a/dashboard/web/src/pages/Publishing.jsx
+++ b/dashboard/web/src/pages/Publishing.jsx
@@ -137,7 +137,8 @@ function Compose({ clients, onClose, onSaved }) {
   const save = async () => {
     setSaving(true); setError(null);
     try {
-      const { platforms, options } = selectionFor(sel, available, f.type);
+      const { platforms, options, problems } = selectionFor(sel, available, f.type);
+      if (problems.length) throw new Error(problems[0]);
       await api("/api/schedule", { method: "POST", body: {
         client: f.client, platforms, options, type: f.type, media: f.media, caption: f.caption, fbCaption: f.fbCaption || undefined,
         collaborators: f.collaborators.split(/[\s,]+/).map((x) => x.replace(/^@/, "")).filter(Boolean), localTime: `${f.date} ${f.time}`,
@@ -170,7 +171,15 @@ function Compose({ clients, onClose, onSaved }) {
       {f.type !== "TEXT" && (
         <Field label="Media" hint="JPG/PNG for images, MP4/MOV for Reels and video stories. Carousel: 2–10 files in order.">
           <div className="flex flex-wrap gap-2 items-center">
-            {f.media.map((m, i) => <span key={m} className="text-[12px] bg-canvas border border-line rounded px-2 py-1">{i + 1}. {m.split(/[\\/]/).pop().replace(/^\d+-/, "")} <button className="text-bad ml-1" onClick={() => set("media", f.media.filter((x) => x !== m))}>×</button></span>)}
+            {f.media.map((m, i) => (
+              <span key={m} className="relative inline-flex flex-col items-center gap-1 text-[11.5px] text-muted">
+                {/\.(mp4|mov|m4v|webm)$/i.test(m)
+                  ? <video src={`/api/schedule/media?path=${encodeURIComponent(m)}`} className="h-24 rounded-md bg-black" muted preload="metadata" />
+                  : <img src={`/api/schedule/media?path=${encodeURIComponent(m)}`} alt="" className="h-24 rounded-md object-cover" />}
+                <span>{i + 1}. {m.split(/[\\/]/).pop().replace(/^\d+-/, "").slice(0, 24)}</span>
+                <button type="button" aria-label="Remove file" className="absolute -top-1.5 -right-1.5 size-5 rounded-full bg-white border border-line text-bad leading-none" onClick={() => set("media", f.media.filter((x) => x !== m))}>×</button>
+              </span>
+            ))}
             <label className="inline-flex items-center gap-1.5 h-8 px-3 rounded-md border border-line-strong text-[13px] cursor-pointer hover:bg-canvas">
               <Upload className="size-3.5" /> {uploading ? "Uploading…" : "Add files"}
               <input id="c-files" type="file" className="hidden" multiple accept="image/jpeg,image/png,video/mp4,video/quicktime" onChange={(e) => upload([...e.target.files])} />
@@ -181,7 +190,7 @@ function Compose({ clients, onClose, onSaved }) {
       <Field label="Caption" hint="Plain text works best for search. Hashtags at the end.">
         <textarea id="c-caption" className="input w-full h-28 py-2" value={f.caption} onChange={(e) => set("caption", e.target.value)} />
       </Field>
-      <Field label="Post to"><PlatformPicker client={f.client} type={f.type} caption={f.caption} value={sel} onChange={setSel} available={available} /></Field>
+      <Field label="Post to"><PlatformPicker client={f.client} type={f.type} caption={f.caption} value={sel} onChange={setSel} available={available} media={f.media} /></Field>
       {sel.platforms.includes("facebook") && (
         <Field label="Facebook caption (optional)" hint="Leave empty to reuse the Instagram caption.">
           <textarea id="c-fbcaption" className="input w-full h-20 py-2" value={f.fbCaption} onChange={(e) => set("fbCaption", e.target.value)} />