diff --git a/src/media/store.header-ext.test.ts b/src/media/store.header-ext.test.ts
new file mode 100644
index 000000000..d24f46c2e
--- /dev/null
+++ b/src/media/store.header-ext.test.ts
@@ -0,0 +1,38 @@
+import fs from "node:fs/promises";
+import path from "node:path";
+import { afterAll, beforeAll, describe, expect, it, vi } from "vitest";
+
+const realOs = await vi.importActual<typeof import("node:os")>("node:os");
+const HOME = path.join(realOs.tmpdir(), "clawdis-home-header-ext-test");
+
+vi.mock("node:os", () => ({
+  default: { homedir: () => HOME, tmpdir: () => realOs.tmpdir() },
+  homedir: () => HOME,
+  tmpdir: () => realOs.tmpdir(),
+}));
+
+vi.mock("./mime.js", async () => {
+  const actual = await vi.importActual<typeof import("./mime.js")>("./mime.js");
+  return {
+    ...actual,
+    detectMime: vi.fn(async () => "audio/opus"),
+  };
+});
+
+const store = await import("./store.js");
+
+describe("media store header extensions", () => {
+  beforeAll(async () => {
+    await fs.rm(HOME, { recursive: true, force: true });
+  });
+
+  afterAll(async () => {
+    await fs.rm(HOME, { recursive: true, force: true });
+  });
+
+  it("prefers header mime extension when sniffed mime lacks mapping", async () => {
+    const buf = Buffer.from("fake-audio");
+    const saved = await store.saveMediaBuffer(buf, "audio/ogg; codecs=opus");
+    expect(path.extname(saved.path)).toBe(".ogg");
+  });
+});
diff --git a/src/media/store.ts b/src/media/store.ts
index 67bf0ddce..4bd99cca7 100644
--- a/src/media/store.ts
+++ b/src/media/store.ts
@@ -169,8 +169,11 @@ export async function saveMediaBuffer(
   const dir = path.join(MEDIA_DIR, subdir);
   await fs.mkdir(dir, { recursive: true });
   const baseId = crypto.randomUUID();
+  const headerExt = extensionForMime(
+    contentType?.split(";")[0]?.trim() ?? undefined,
+  );
   const mime = await detectMime({ buffer, headerMime: contentType });
-  const ext = extensionForMime(mime);
+  const ext = headerExt ?? extensionForMime(mime);
   const id = ext ? `${baseId}${ext}` : baseId;
   const dest = path.join(dir, id);
   await fs.writeFile(dest, buffer);