diff --git a/skills/media-use/.gitignore b/skills/media-use/.gitignore
new file mode 100644
index 000000000..17df1e2db
--- /dev/null
+++ b/skills/media-use/.gitignore
@@ -0,0 +1 @@
+eval-report.html
diff --git a/skills/media-use/scripts/lib/adopt.mjs b/skills/media-use/scripts/lib/adopt.mjs
new file mode 100644
index 000000000..6461262ba
--- /dev/null
+++ b/skills/media-use/scripts/lib/adopt.mjs
@@ -0,0 +1,109 @@
+import { readdirSync, statSync, existsSync } from "node:fs";
+import { join, extname, basename } from "node:path";
+import { readManifest, appendRecord, nextId } from "./manifest.mjs";
+import { regenerateIndex } from "./index-gen.mjs";
+import { probe } from "./probe.mjs";
+
+const AUDIO_EXT = new Set([".mp3", ".wav", ".ogg", ".m4a", ".aac"]);
+const IMAGE_EXT = new Set([".jpg", ".jpeg", ".png", ".gif", ".webp", ".svg", ".ico"]);
+const VIDEO_EXT = new Set([".mp4", ".webm", ".mov"]);
+
+function inferType(filePath) {
+  const ext = extname(filePath).toLowerCase();
+  if (AUDIO_EXT.has(ext)) {
+    const lower = filePath.toLowerCase();
+    if (lower.includes("/bgm/") || lower.includes("/music/") || lower.startsWith("bgm/")) return "bgm";
+    if (lower.includes("/sfx/") || lower.includes("/sound") || lower.startsWith("sfx/")) return "sfx";
+    if (lower.includes("/voice/") || lower.includes("/narrat") || lower.startsWith("voice/")) return "voice";
+    return "bgm";
+  }
+  if (IMAGE_EXT.has(ext)) {
+    if (ext === ".svg" || ext === ".ico") return "icon";
+    return "image";
+  }
+  if (VIDEO_EXT.has(ext)) return "video";
+  return null;
+}
+
+function walkDir(dir, base = "") {
+  const files = [];
+  if (!existsSync(dir)) return files;
+  for (const entry of readdirSync(dir, { withFileTypes: true })) {
+    const rel = base ? `${base}/${entry.name}` : entry.name;
+    if (entry.isDirectory()) {
+      files.push(...walkDir(join(dir, entry.name), rel));
+    } else {
+      files.push(rel);
+    }
+  }
+  return files;
+}
+
+export function scanExistingAssets(projectDir) {
+  const assetsDir = join(projectDir, "assets");
+  if (!existsSync(assetsDir)) return [];
+
+  const files = walkDir(assetsDir);
+  const found = [];
+  for (const rel of files) {
+    const type = inferType(rel);
+    if (!type) continue;
+    const fullPath = join(assetsDir, rel);
+    const stat = statSync(fullPath);
+    const meta = probe(fullPath);
+    found.push({
+      relativePath: `assets/${rel}`,
+      type,
+      size: stat.size,
+      name: basename(rel, extname(rel)),
+      ...meta,
+    });
+  }
+  return found;
+}
+
+export function adoptExistingAssets(projectDir) {
+  const existing = scanExistingAssets(projectDir);
+  if (existing.length === 0) return [];
+
+  const manifest = readManifest(projectDir);
+  const knownPaths = new Set(manifest.map((r) => r.path));
+
+  const adopted = [];
+  for (const asset of existing) {
+    if (knownPaths.has(asset.relativePath)) continue;
+
+    const id = nextId(projectDir, asset.type);
+    const record = {
+      id,
+      type: asset.type,
+      path: asset.relativePath,
+      source: "existing",
+      description: asset.name.replace(/[-_]/g, " "),
+      ...(asset.duration != null && { duration: asset.duration }),
+      ...(asset.width != null && { width: asset.width }),
+      ...(asset.height != null && { height: asset.height }),
+      provenance: { provider: "local", adopted: true },
+    };
+    appendRecord(projectDir, record);
+    adopted.push(record);
+  }
+
+  if (adopted.length > 0) regenerateIndex(projectDir);
+  return adopted;
+}
+
+export function findExistingAsset(projectDir, intent, type) {
+  const assetsDir = join(projectDir, "assets");
+  if (!existsSync(assetsDir)) return null;
+  const lower = intent.toLowerCase();
+  for (const rel of walkDir(assetsDir)) {
+    const t = inferType(rel);
+    if (!t || (type && t !== type)) continue;
+    const name = basename(rel, extname(rel)).toLowerCase().replace(/[-_]/g, " ");
+    if (name.includes(lower) || lower.includes(name)) {
+      return { relativePath: `assets/${rel}`, type: t, name: basename(rel, extname(rel)) };
+    }
+  }
+  return null;
+}
diff --git a/skills/media-use/scripts/lib/cache.mjs b/skills/media-use/scripts/lib/cache.mjs
new file mode 100644
index 000000000..d2809b895
--- /dev/null
+++ b/skills/media-use/scripts/lib/cache.mjs
@@ -0,0 +1,126 @@
+import {
+  readFileSync,
+  writeFileSync,
+  mkdirSync,
+  existsSync,
+  copyFileSync,
+} from "node:fs";
+import { join, basename } from "node:path";
+import { createHash } from "node:crypto";
+import { homedir } from "node:os";
+import { readManifest, appendRecord } from "./manifest.mjs";
+
+const SCHEMA_PREFIX = "mu-v1-";
+const KEY_HEX_CHARS = 16;
+const COMPLETE_SENTINEL = ".hf-complete";
+
+export function globalMediaDir() {
+  return join(homedir(), ".media");
+}
+
+export function contentHash(filePath) {
+  const bytes = readFileSync(filePath);
+  return createHash("sha256").update(bytes).digest("hex");
+}
+
+function cacheEntryDir(rootDir, sha) {
+  return join(rootDir, SCHEMA_PREFIX + sha.slice(0, KEY_HEX_CHARS));
+}
+
+function isComplete(entryDir) {
+  return existsSync(join(entryDir, COMPLETE_SENTINEL));
+}
+
+function markComplete(entryDir) {
+  writeFileSync(join(entryDir, COMPLETE_SENTINEL), "", "utf8");
+}
+
+function readGlobalManifest() {
+  return readManifest(globalMediaDir());
+}
+
+function validateCacheHit(match) {
+  if (!match?.sha) return null;
+  return isComplete(cacheEntryDir(globalMediaDir(), match.sha)) ? match : null;
+}
+
+export function cacheGet(prompt, type) {
+  return validateCacheHit(
+    readGlobalManifest().find(
+      (r) =>
+        r.reusable &&
+        r.provenance?.prompt === prompt &&
+        (type == null || r.type === type),
+    ),
+  );
+}
+
+export function cacheGetByEntity(entity) {
+  const lower = entity.toLowerCase();
+  return validateCacheHit(
+    readGlobalManifest().find(
+      (r) => r.reusable && r.entity && r.entity.toLowerCase() === lower,
+    ),
+  );
+}
+
+export function cachePut(filePath, record) {
+  const sha = contentHash(filePath);
+  const dir = globalMediaDir();
+  const entryDir = cacheEntryDir(dir, sha);
+  mkdirSync(entryDir, { recursive: true });
+
+  const dest = join(entryDir, basename(filePath));
+  copyFileSync(filePath, dest);
+  markComplete(entryDir);
+
+  const globalRecord = {
+    ...record,
+    sha,
+    reusable: true,
+    cached_path: dest,
+  };
+  appendRecord(globalMediaDir(), globalRecord);
+  return { sha, cached_path: dest };
+}
+
+export function importFromCache(cacheRecord, projectDir, localId, localPath) {
+  const sha = cacheRecord.sha;
+  const entryDir = cacheEntryDir(globalMediaDir(), sha);
+  if (!isComplete(entryDir)) return null;
+
+  const cachedFile = cacheRecord.cached_path;
+  if (!cachedFile || !existsSync(cachedFile)) return null;
+
+  mkdirSync(join(projectDir, ".media"), { recursive: true });
+  const fullDest = join(projectDir, localPath);
+  mkdirSync(join(fullDest, ".."), { recursive: true });
+  copyFileSync(cachedFile, fullDest);
+
+  const projectRecord = {
+    ...cacheRecord,
+    id: localId,
+    path: localPath,
+    provenance: {
+      ...cacheRecord.provenance,
+      imported_from: sha,
+    },
+  };
+  delete projectRecord.sha;
+  delete projectRecord.reusable;
+  delete projectRecord.cached_path;
+
+  return projectRecord;
+}
+
+export function promote(projectDir, id) {
+  const records = readManifest(projectDir);
+  const record = records.find((r) => r.id === id);
+  if (!record) throw new Error(`asset not found in project manifest: ${id}`);
+
+  const filePath = join(projectDir, record.path);
+  if (!existsSync(filePath))
+    throw new Error(`asset file not found: ${filePath}`);
+
+  return cachePut(filePath, record);
+}
diff --git a/skills/media-use/scripts/lib/freeze.mjs b/skills/media-use/scripts/lib/freeze.mjs
new file mode 100644
index 000000000..ab62f568d
--- /dev/null
+++ b/skills/media-use/scripts/lib/freeze.mjs
@@ -0,0 +1,18 @@
+import { writeFileSync, copyFileSync, mkdirSync } from "node:fs";
+import { dirname } from "node:path";
+
+export async function freezeUrl(url, destPath) {
+  const res = await fetch(url);
+  if (!res.ok) throw new Error(`freeze failed: HTTP ${res.status} for ${String(url).slice(0, 80)}`);
+  const bytes = Buffer.from(await res.arrayBuffer());
+  if (bytes.length === 0)
+    throw new Error(`freeze failed: empty response for ${String(url).slice(0, 80)}`);
+  mkdirSync(dirname(destPath), { recursive: true });
+  writeFileSync(destPath, bytes);
+  return bytes.length;
+}
+
+export function freezeLocalFile(srcPath, destPath) {
+  mkdirSync(dirname(destPath), { recursive: true });
+  copyFileSync(srcPath, destPath);
+}
diff --git a/skills/media-use/scripts/lib/index-gen.mjs b/skills/media-use/scripts/lib/index-gen.mjs
new file mode 100644
index 000000000..65b019a92
--- /dev/null
+++ b/skills/media-use/scripts/lib/index-gen.mjs
@@ -0,0 +1,63 @@
+import { writeFileSync, mkdirSync } from "node:fs";
+import { dirname } from "node:path";
+import { readManifest, indexPath } from "./manifest.mjs";
+
+function pad(str, len) {
+  return String(str ?? "").padEnd(len);
+}
+
+function formatDur(record) {
+  if (record.duration == null) return "—";
+  return `${record.duration}s`;
+}
+
+function formatDims(record) {
+  if (record.width && record.height) return `${record.width}×${record.height}`;
+  if (record.type === "icon" && record.transparent) return "svg";
+  return "—";
+}
+
+export function generateIndexContent(records) {
+  const count = records.length;
+  const header = `# .media · ${count} asset${count === 1 ? "" : "s"}\n`;
+  if (count === 0) return header;
+
+  const cols = { id: 4, type: 5, dur: 4, dims: 5, path: 5, desc: 11 };
+  for (const r of records) {
+    cols.id = Math.max(cols.id, (r.id ?? "").length);
+    cols.type = Math.max(cols.type, (r.type ?? "").length);
+    cols.dur = Math.max(cols.dur, formatDur(r).length);
+    cols.dims = Math.max(cols.dims, formatDims(r).length);
+    cols.path = Math.max(cols.path, (r.path ?? "").length);
+  }
+
+  const heading =
+    pad("id", cols.id + 2) +
+    pad("type", cols.type + 2) +
+    pad("dur", cols.dur + 2) +
+    pad("dims", cols.dims + 2) +
+    pad("path", cols.path + 2) +
+    "description";
+
+  const lines = [header, heading];
+  for (const r of records) {
+    lines.push(
+      pad(r.id, cols.id + 2) +
+        pad(r.type, cols.type + 2) +
+        pad(formatDur(r), cols.dur + 2) +
+        pad(formatDims(r), cols.dims + 2) +
+        pad(r.path, cols.path + 2) +
+        (r.description ?? ""),
+    );
+  }
+  return lines.join("\n") + "\n";
+}
+
+export function regenerateIndex(projectDir) {
+  const records = readManifest(projectDir);
+  const content = generateIndexContent(records);
+  const p = indexPath(projectDir);
+  mkdirSync(dirname(p), { recursive: true });
+  writeFileSync(p, content);
+  return content;
+}
diff --git a/skills/media-use/scripts/lib/manifest.mjs b/skills/media-use/scripts/lib/manifest.mjs
new file mode 100644
index 000000000..a32ea181b
--- /dev/null
+++ b/skills/media-use/scripts/lib/manifest.mjs
@@ -0,0 +1,91 @@
+import { readFileSync, appendFileSync, mkdirSync, existsSync } from "node:fs";
+import { join } from "node:path";
+
+const MANIFEST_FILE = "manifest.jsonl";
+const INDEX_FILE = "index.md";
+
+const TYPE_DIRS = {
+  bgm: "audio/bgm",
+  sfx: "audio/sfx",
+  voice: "audio/voice",
+  image: "images",
+  icon: "images",
+  brand: "images",
+  video: "video",
+};
+
+export function mediaDir(projectDir) {
+  return join(projectDir, ".media");
+}
+
+export function manifestPath(projectDir) {
+  return join(mediaDir(projectDir), MANIFEST_FILE);
+}
+
+export function indexPath(projectDir) {
+  return join(mediaDir(projectDir), INDEX_FILE);
+}
+
+export function typeSubdir(type) {
+  const sub = TYPE_DIRS[type];
+  if (!sub) throw new Error(`unknown media type: ${type}`);
+  return sub;
+}
+
+export function typeDirPath(projectDir, type) {
+  return join(mediaDir(projectDir), typeSubdir(type));
+}
+
+export function readManifest(projectDir) {
+  const p = manifestPath(projectDir);
+  if (!existsSync(p)) return [];
+  const raw = readFileSync(p, "utf8");
+  const records = [];
+  for (const line of raw.split(/\r?\n/)) {
+    const trimmed = line.trim();
+    if (!trimmed) continue;
+    try {
+      records.push(JSON.parse(trimmed));
+    } catch {
+      // ponytail: skip malformed lines, don't crash
+    }
+  }
+  return records;
+}
+
+export function appendRecord(projectDir, record) {
+  const dir = mediaDir(projectDir);
+  mkdirSync(dir, { recursive: true });
+  const typeDir = typeDirPath(projectDir, record.type);
+  mkdirSync(typeDir, { recursive: true });
+
+  const p = manifestPath(projectDir);
+  const line = JSON.stringify(record) + "\n";
+  appendFileSync(p, line);
+}
+
+export function findByPrompt(projectDir, prompt, type) {
+  const records = readManifest(projectDir);
+  return (
+    records.find((r) => r.provenance?.prompt === prompt && (type == null || r.type === type)) ||
+    null
+  );
+}
+
+export function findByEntity(projectDir, entity) {
+  const lower = entity.toLowerCase();
+  const records = readManifest(projectDir);
+  return records.find((r) => r.entity && r.entity.toLowerCase() === lower) || null;
+}
+
+export function nextId(projectDir, type) {
+  const records = readManifest(projectDir);
+  const prefix = type;
+  let max = 0;
+  for (const r of records) {
+    if (r.type !== type) continue;
+    const m = r.id?.match(new RegExp(`^${prefix}_(\\d+)$`));
+    if (m) max = Math.max(max, parseInt(m[1], 10));
+  }
+  return `${prefix}_${String(max + 1).padStart(3, "0")}`;
+}
diff --git a/skills/media-use/scripts/lib/manifest.test.mjs b/skills/media-use/scripts/lib/manifest.test.mjs
new file mode 100644
index 000000000..b03ce59f7
--- /dev/null
+++ b/skills/media-use/scripts/lib/manifest.test.mjs
@@ -0,0 +1,295 @@
+import { strict as assert } from "node:assert";
+import { mkdtempSync, rmSync, readFileSync, writeFileSync, mkdirSync, existsSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import {
+  readManifest,
+  appendRecord,
+  findByPrompt,
+  findByEntity,
+  nextId,
+  manifestPath,
+  mediaDir,
+  typeDirPath,
+} from "./manifest.mjs";
+import { regenerateIndex, generateIndexContent } from "./index-gen.mjs";
+import {
+  contentHash,
+  cachePut,
+  cacheGet,
+  cacheGetByEntity,
+  importFromCache,
+  promote,
+} from "./cache.mjs";
+
+let tmp;
+
+function setup() {
+  tmp = mkdtempSync(join(tmpdir(), "mu-test-"));
+}
+
+function cleanup() {
+  if (tmp) rmSync(tmp, { recursive: true, force: true });
+}
+
+function makeRecord(overrides = {}) {
+  return {
+    id: "bgm_001",
+    type: "bgm",
+    path: ".media/audio/bgm/bgm_001.wav",
+    source: "search",
+    description: "soft minimal ambient",
+    duration: 11,
+    provenance: { provider: "heygen.audio.sounds", prompt: "subtle tech" },
+    ...overrides,
+  };
+}
+
+function runTests() {
+  const tests = [];
+
+  function test(name, fn) {
+    tests.push({ name, fn });
+  }
+
+  // --- manifest.mjs ---
+
+  test("readManifest returns empty array when no manifest exists", () => {
+    setup();
+    const result = readManifest(tmp);
+    assert.deepStrictEqual(result, []);
+    cleanup();
+  });
+
+  test("appendRecord writes valid JSONL and readManifest parses it back", () => {
+    setup();
+    const record = makeRecord();
+    appendRecord(tmp, record);
+    const records = readManifest(tmp);
+    assert.equal(records.length, 1);
+    assert.deepStrictEqual(records[0], record);
+    cleanup();
+  });
+
+  test("appendRecord creates .media/ and type subdirs on first write", () => {
+    setup();
+    appendRecord(tmp, makeRecord());
+    assert.ok(existsSync(mediaDir(tmp)));
+    assert.ok(existsSync(typeDirPath(tmp, "bgm")));
+    cleanup();
+  });
+
+  test("appendRecord appends multiple records", () => {
+    setup();
+    appendRecord(tmp, makeRecord({ id: "bgm_001" }));
+    appendRecord(tmp, makeRecord({ id: "bgm_002", provenance: { prompt: "energetic" } }));
+    const records = readManifest(tmp);
+    assert.equal(records.length, 2);
+    assert.equal(records[0].id, "bgm_001");
+    assert.equal(records[1].id, "bgm_002");
+    cleanup();
+  });
+
+  test("findByPrompt returns exact-match record", () => {
+    setup();
+    appendRecord(tmp, makeRecord());
+    const found = findByPrompt(tmp, "subtle tech", "bgm");
+    assert.ok(found);
+    assert.equal(found.id, "bgm_001");
+    cleanup();
+  });
+
+  test("findByPrompt returns null on miss", () => {
+    setup();
+    appendRecord(tmp, makeRecord());
+    assert.equal(findByPrompt(tmp, "nonexistent", "bgm"), null);
+    cleanup();
+  });
+
+  test("findByPrompt filters by type", () => {
+    setup();
+    appendRecord(tmp, makeRecord({ type: "sfx" }));
+    assert.equal(findByPrompt(tmp, "subtle tech", "bgm"), null);
+    assert.ok(findByPrompt(tmp, "subtle tech", "sfx"));
+    cleanup();
+  });
+
+  test("findByEntity matches case-insensitively", () => {
+    setup();
+    appendRecord(tmp, makeRecord({ entity: "GitHub", type: "icon" }));
+    assert.ok(findByEntity(tmp, "github"));
+    assert.ok(findByEntity(tmp, "GITHUB"));
+    assert.equal(findByEntity(tmp, "gitlab"), null);
+    cleanup();
+  });
+
+  test("nextId generates sequential ids", () => {
+    setup();
+    assert.equal(nextId(tmp, "bgm"), "bgm_001");
+    appendRecord(tmp, makeRecord({ id: "bgm_001" }));
+    assert.equal(nextId(tmp, "bgm"), "bgm_002");
+    appendRecord(tmp, makeRecord({ id: "bgm_002" }));
+    assert.equal(nextId(tmp, "bgm"), "bgm_003");
+    cleanup();
+  });
+
+  // --- index-gen.mjs ---
+
+  test("regenerateIndex produces plain-column table", () => {
+    setup();
+    appendRecord(tmp, makeRecord());
+    regenerateIndex(tmp);
+    const content = readFileSync(join(tmp, ".media", "index.md"), "utf8");
+    assert.ok(content.includes("# .media · 1 asset"));
+    assert.ok(content.includes("bgm_001"));
+    assert.ok(content.includes("soft minimal ambient"));
+    assert.ok(content.includes("11s"));
+    cleanup();
+  });
+
+  test("regenerateIndex handles empty manifest", () => {
+    setup();
+    mkdirSync(join(tmp, ".media"), { recursive: true });
+    writeFileSync(manifestPath(tmp), "");
+    regenerateIndex(tmp);
+    const content = readFileSync(join(tmp, ".media", "index.md"), "utf8");
+    assert.ok(content.includes("# .media · 0 assets"));
+    cleanup();
+  });
+
+  test("generateIndexContent includes dims for images", () => {
+    const records = [
+      makeRecord({ id: "img_001", type: "image", width: 1920, height: 1080, duration: null }),
+    ];
+    const content = generateIndexContent(records);
+    assert.ok(content.includes("1920×1080"));
+    assert.ok(content.includes("img_001"));
+  });
+
+  test("regenerateIndex matches manifest content after multiple writes", () => {
+    setup();
+    appendRecord(tmp, makeRecord({ id: "bgm_001" }));
+    appendRecord(tmp, makeRecord({ id: "sfx_001", type: "sfx", description: "whoosh", duration: 3 }));
+    regenerateIndex(tmp);
+    const content = readFileSync(join(tmp, ".media", "index.md"), "utf8");
+    assert.ok(content.includes("# .media · 2 assets"));
+    assert.ok(content.includes("bgm_001"));
+    assert.ok(content.includes("sfx_001"));
+    assert.ok(content.includes("whoosh"));
+    cleanup();
+  });
+
+  // --- cache.mjs ---
+
+  test("cacheGet returns null when cache is empty", () => {
+    const result = cacheGet("nonexistent prompt", "bgm");
+    assert.equal(result, null);
+  });
+
+  test("cachePut + cacheGet round-trip", () => {
+    setup();
+    const filePath = join(tmp, "test.wav");
+    writeFileSync(filePath, "fake audio bytes for testing");
+    const record = makeRecord({ provenance: { prompt: "cache test" } });
+
+    const { sha } = cachePut(filePath, record);
+    assert.ok(sha);
+    assert.equal(sha.length, 64);
+
+    const found = cacheGet("cache test", "bgm");
+    assert.ok(found);
+    assert.equal(found.reusable, true);
+    assert.equal(found.sha, sha);
+    cleanup();
+  });
+
+  test("cacheGetByEntity finds cached asset", () => {
+    setup();
+    const filePath = join(tmp, "logo.png");
+    writeFileSync(filePath, "fake png bytes");
+    const record = makeRecord({
+      type: "icon",
+      entity: "TestCorp",
+      provenance: { prompt: "TestCorp logo" },
+    });
+
+    cachePut(filePath, record);
+    const found = cacheGetByEntity("testcorp");
+    assert.ok(found);
+    assert.equal(found.entity, "TestCorp");
+    cleanup();
+  });
+
+  test("contentHash is deterministic", () => {
+    setup();
+    const filePath = join(tmp, "det.bin");
+    writeFileSync(filePath, "deterministic content");
+    const h1 = contentHash(filePath);
+    const h2 = contentHash(filePath);
+    assert.equal(h1, h2);
+    cleanup();
+  });
+
+  test("promote copies project asset to global cache", () => {
+    setup();
+    const record = makeRecord();
+    appendRecord(tmp, record);
+    const filePath = join(tmp, record.path);
+    mkdirSync(join(filePath, ".."), { recursive: true });
+    writeFileSync(filePath, "promotable audio data");
+
+    const { sha } = promote(tmp, "bgm_001");
+    assert.ok(sha);
+
+    const cached = cacheGet("subtle tech", "bgm");
+    assert.ok(cached);
+    assert.equal(cached.sha, sha);
+    cleanup();
+  });
+
+  test("importFromCache copies cached file into project", () => {
+    setup();
+    const filePath = join(tmp, "source.wav");
+    writeFileSync(filePath, "importable audio");
+    const record = makeRecord({ provenance: { prompt: "import test" } });
+    const { sha } = cachePut(filePath, record);
+
+    const cached = cacheGet("import test", "bgm");
+    const projectDir = mkdtempSync(join(tmpdir(), "mu-import-"));
+    const imported = importFromCache(
+      cached,
+      projectDir,
+      "bgm_001",
+      ".media/audio/bgm/bgm_001.wav",
+    );
+
+    assert.ok(imported);
+    assert.equal(imported.id, "bgm_001");
+    assert.equal(imported.provenance.imported_from, sha);
+    assert.ok(existsSync(join(projectDir, ".media/audio/bgm/bgm_001.wav")));
+
+    rmSync(projectDir, { recursive: true, force: true });
+    cleanup();
+  });
+
+  // --- run ---
+
+  let passed = 0;
+  let failed = 0;
+  for (const { name, fn } of tests) {
+    try {
+      fn();
+      passed++;
+      console.log(`  \x1b[32m✓\x1b[0m ${name}`);
+    } catch (err) {
+      failed++;
+      console.log(`  \x1b[31m✗\x1b[0m ${name}`);
+      console.log(`    ${err.message}`);
+    }
+  }
+  console.log(`\n${passed} passed, ${failed} failed`);
+  if (failed > 0) process.exit(1);
+}
+
+console.log("media-use · manifest/index/cache tests\n");
+runTests();
diff --git a/skills/media-use/scripts/lib/probe.mjs b/skills/media-use/scripts/lib/probe.mjs
new file mode 100644
index 000000000..854b230e5
--- /dev/null
+++ b/skills/media-use/scripts/lib/probe.mjs
@@ -0,0 +1,34 @@
+import { execSync } from "node:child_process";
+import { extname } from "node:path";
+
+const IMAGE_EXT = new Set([".jpg", ".jpeg", ".png", ".gif", ".webp", ".svg", ".ico"]);
+
+export function probe(filePath) {
+  const ext = extname(filePath).toLowerCase();
+  if (ext === ".svg") return { width: null, height: null, duration: null, codec: "svg" };
+
+  try {
+    const raw = execSync(
+      `ffprobe -v quiet -print_format json -show_format -show_streams "${filePath}"`,
+      { encoding: "utf8", timeout: 5000 },
+    );
+    const info = JSON.parse(raw);
+    const stream = info.streams?.[0];
+    const format = info.format;
+
+    const isImage = IMAGE_EXT.has(ext);
+    const duration = isImage ? null : parseFloat(format?.duration) || parseFloat(stream?.duration) || null;
+    const width = parseInt(stream?.width, 10) || null;
+    const height = parseInt(stream?.height, 10) || null;
+    const codec = stream?.codec_name || null;
+
+    return {
+      duration: duration != null ? Math.round(duration * 10) / 10 : null,
+      width,
+      height,
+      codec,
+    };
+  } catch {
+    return { duration: null, width: null, height: null, codec: null };
+  }
+}