diff --git a/skills-manifest.json b/skills-manifest.json
index 3c2a3a426..aae12feab 100644
--- a/skills-manifest.json
+++ b/skills-manifest.json
@@ -46,7 +46,7 @@
       "files": 10
     },
     "media-use": {
-      "hash": "b982d0f7c710bf23",
+      "hash": "79605197974012b2",
       "files": 101
     },
     "motion-graphics": {
diff --git a/skills/media-use/audio/scripts/audio.mjs b/skills/media-use/audio/scripts/audio.mjs
index a332dc7d3..bc005eeff 100644
--- a/skills/media-use/audio/scripts/audio.mjs
+++ b/skills/media-use/audio/scripts/audio.mjs
@@ -145,7 +145,7 @@ if (only.has("tts") && lines.length) {
     }
     const rel = `assets/voice/${id}.wav`;
     const abs = join(hyperframesDir, rel);
-    const { ok, words } = await synthesizeOne({
+    const { ok, words, error } = await synthesizeOne({
       provider: ttsProvider,
       text,
       voiceId,
@@ -155,7 +155,7 @@ if (only.has("tts") && lines.length) {
       hyperframesDir,
     });
     if (!ok) {
-      anomalies.push(`line ${id}: TTS failed — omitted`);
+      anomalies.push(`line ${id}: TTS failed — omitted${error ? ` (${error})` : ""}`);
       return null;
     }
     let wordArr = words; // heygen: native; else transcribe
diff --git a/skills/media-use/audio/scripts/lib/tts.mjs b/skills/media-use/audio/scripts/lib/tts.mjs
index e46f7545f..a54c150e1 100644
--- a/skills/media-use/audio/scripts/lib/tts.mjs
+++ b/skills/media-use/audio/scripts/lib/tts.mjs
@@ -225,9 +225,10 @@ save(audio, sys.argv[3])
 `;
 
 // ── synthesize one line ───────────────────────────────────────────────────────
-// Writes wav at wavAbs. Returns { ok, words } — words is the raw
+// Writes wav at wavAbs. Returns { ok, words, error } — words is the raw
 // [{text,start,end}] array for HeyGen (native), or null for ElevenLabs/Kokoro
-// (caller must transcribeWav). Never throws; failures return { ok:false }.
+// (caller must transcribeWav). Never throws; failures return { ok:false, error }
+// where `error` states WHY (so the caller can surface it, not a bare "TTS failed").
 export async function synthesizeOne({
   provider,
   text,
@@ -259,34 +260,61 @@ export async function synthesizeOne({
       wavAbs,
     ]);
     const r = await spawnP(cmd, args, {});
-    return { ok: r.status === 0 && existsSync(wavAbs), words: null };
+    return synthResult(r, wavAbs, "elevenlabs (python)");
   }
   // kokoro — via the published CLI; --output is relative to the project dir.
   const wavRel = relTo(hyperframesDir, wavAbs);
   const args = ["hyperframes", "tts", writeTmpText(text), "--voice", voiceId, "--output", wavRel];
   if (lang !== "en") args.push("--lang", lang);
   const r = await spawnP("npx", args, { cwd: hyperframesDir });
-  return { ok: r.status === 0 && existsSync(wavAbs), words: null };
+  return synthResult(r, wavAbs, "kokoro (npx hyperframes tts)");
 }
 
-async function synthesizeHeygen({ text, voiceId, lang, speed, wavAbs }) {
+// Shape a spawn result into { ok, words, error }, naming why on failure so the
+// caller surfaces it instead of a bare "TTS failed".
+export function synthResult(r, wavAbs, label) {
+  if (r.status === 0 && existsSync(wavAbs)) return { ok: true, words: null };
+  const why =
+    r.status !== 0 ? `${label} exited with status ${r.status}` : `${label} produced no wav file`;
+  return { ok: false, words: null, error: why };
+}
+
+// `deps` is injectable for tests; production uses the real network/ffmpeg impls.
+// Every failure path returns an `error` string so the caller can surface WHY a
+// line was dropped instead of the bare "TTS failed" that hid the real cause
+// (e.g. an HTTP 402 plan_upgrade_required thrown by heygenJSON was swallowed).
+export async function synthesizeHeygen({ text, voiceId, lang, speed, wavAbs }, deps = {}) {
+  const requestJSON = deps.heygenJSON ?? heygenJSON;
+  const authHeaders = deps.heygenAuthHeaders ?? heygenAuthHeaders;
+  const fetchImpl = deps.fetch ?? fetch;
+  const transcode = deps.transcodeToWav ?? transcodeToWav;
   try {
     const body = { text, voice_id: voiceId, speed };
     if (lang !== "en") body.language = lang;
-    const payload = await heygenJSON(`/voices/speech`, {
+    const payload = await requestJSON(`/voices/speech`, {
       method: "POST",
-      headers: heygenAuthHeaders(),
+      headers: authHeaders(),
       body,
     });
     const inner = payload.data ?? payload;
-    if (!inner.audio_url) return { ok: false, words: null };
-    const res = await fetch(inner.audio_url);
-    if (!res.ok) return { ok: false, words: null };
+    if (!inner.audio_url) {
+      return { ok: false, words: null, error: "HeyGen /voices/speech returned no audio_url" };
+    }
+    const res = await fetchImpl(inner.audio_url);
+    if (!res.ok) {
+      return { ok: false, words: null, error: `audio_url fetch failed: HTTP ${res.status}` };
+    }
     const bytes = Buffer.from(await res.arrayBuffer());
     // .wav output → transcode to 44.1k mono; .mp3 → raw bytes (no ffmpeg). The
     // engine always asks for .wav; the standalone heygen-tts CLI may ask for .mp3.
     if (wavAbs.endsWith(".wav")) {
-      if (!transcodeToWav(bytes, wavAbs)) return { ok: false, words: null };
+      if (!transcode(bytes, wavAbs)) {
+        return {
+          ok: false,
+          words: null,
+          error: "wav transcode failed (ffmpeg — see output above)",
+        };
+      }
     } else {
       mkdirSync(dirname(wavAbs), { recursive: true });
       writeFileSync(wavAbs, bytes);
@@ -298,8 +326,8 @@ async function synthesizeHeygen({ text, voiceId, lang, speed, wavAbs }) {
           .map((w) => ({ text: w.word, start: w.start, end: w.end }))
       : [];
     return { ok: true, words };
-  } catch {
-    return { ok: false, words: null };
+  } catch (e) {
+    return { ok: false, words: null, error: e?.message ? String(e.message) : String(e) };
   }
 }
 
diff --git a/skills/media-use/audio/scripts/lib/tts.test.mjs b/skills/media-use/audio/scripts/lib/tts.test.mjs
index cb37db958..7e18b77a8 100644
--- a/skills/media-use/audio/scripts/lib/tts.test.mjs
+++ b/skills/media-use/audio/scripts/lib/tts.test.mjs
@@ -3,7 +3,13 @@ import assert from "node:assert/strict";
 import { mkdtempSync, writeFileSync, chmodSync, rmSync, existsSync } from "node:fs";
 import { join, dirname } from "node:path";
 import { tmpdir } from "node:os";
-import { parseFfmpegDurationBanner, ffprobeDuration, synthesizeOne } from "./tts.mjs";
+import {
+  parseFfmpegDurationBanner,
+  ffprobeDuration,
+  synthesizeOne,
+  synthesizeHeygen,
+  synthResult,
+} from "./tts.mjs";
 
 test("parseFfmpegDurationBanner reads ffmpeg's stderr Duration line", () => {
   const stderr = [
@@ -87,3 +93,46 @@ test("synthesizeOne(elevenlabs) creates the output dir before writing", async ()
     rmSync(dir, { recursive: true, force: true });
   }
 });
+
+test("synthesizeHeygen surfaces a thrown HTTP error (e.g. 402) instead of swallowing it", async () => {
+  const res = await synthesizeHeygen(
+    { text: "hi", voiceId: "v1", lang: "en", speed: 1, wavAbs: "/tmp/x.wav" },
+    {
+      heygenAuthHeaders: () => ({}),
+      heygenJSON: async () => {
+        throw new Error("HeyGen POST /voices/speech → HTTP 402\nplan_upgrade_required");
+      },
+    },
+  );
+  assert.equal(res.ok, false);
+  assert.match(res.error, /402/);
+  assert.match(res.error, /plan_upgrade_required/);
+});
+
+test("synthesizeHeygen surfaces a failed audio_url fetch with its status", async () => {
+  const res = await synthesizeHeygen(
+    { text: "hi", voiceId: "v1", lang: "en", speed: 1, wavAbs: "/tmp/x.wav" },
+    {
+      heygenAuthHeaders: () => ({}),
+      heygenJSON: async () => ({ data: { audio_url: "http://audio.example/x" } }),
+      fetch: async () => ({ ok: false, status: 403 }),
+    },
+  );
+  assert.equal(res.ok, false);
+  assert.match(res.error, /HTTP 403/);
+});
+
+test("synthesizeHeygen reports a missing audio_url", async () => {
+  const res = await synthesizeHeygen(
+    { text: "hi", voiceId: "v1", lang: "en", speed: 1, wavAbs: "/tmp/x.wav" },
+    { heygenAuthHeaders: () => ({}), heygenJSON: async () => ({}) },
+  );
+  assert.equal(res.ok, false);
+  assert.match(res.error, /no audio_url/);
+});
+
+test("synthResult names a non-zero subprocess exit", () => {
+  const res = synthResult({ status: 2 }, "/tmp/none.wav", "kokoro (npx hyperframes tts)");
+  assert.equal(res.ok, false);
+  assert.match(res.error, /kokoro .* exited with status 2/);
+});