fix(studio-server): reject a peak map whose decode exits nonzero

A decode that emits some samples and then fails no longer resolves as a
complete map, so /peaks cannot cache a truncated clipping map.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: vanceingalls

packages/studio-server/src/helpers/peakMap.decodeFailure.test.ts

@@ -0,0 +1,29 @@
+import { chmodSync, mkdtempSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { describe, expect, it, vi } from "vitest";
+
+// Stand-in binaries: ffprobe reports a stereo stream, ffmpeg writes samples and then fails.
+const fakeBin = vi.hoisted(() => ({ dir: "" }));
+vi.mock("@hyperframes/parsers/ff-binaries", () => ({
+  findFfBinary: (name: string) => join(fakeBin.dir, name),
+}));
+
+import { decodePeakMap } from "./peakMap";
+
+describe("decodePeakMap, decode failure", () => {
+  it.skipIf(process.platform === "win32")(
+    "rejects partial output when ffmpeg exits nonzero",
+    async () => {
+      fakeBin.dir = mkdtempSync(join(tmpdir(), "hf-fake-ff-"));
+      const script = (name: string, body: string) => {
+        const file = join(fakeBin.dir, name);
+        writeFileSync(file, `#!/bin/sh\n${body}\n`);
+        chmodSync(file, 0o755);
+      };
+      script("ffprobe", "echo 2");
+      script("ffmpeg", "head -c 38400 /dev/zero; exit 1");
+      await expect(decodePeakMap("truncated.mov")).rejects.toThrow(/exit 1/);
+    },
+  );
+});

packages/studio-server/src/helpers/peakMap.ts

@@ -107,8 +107,12 @@ export async function decodePeakMap(mediaPath: string): Promise<number[]> {
     const acc = createPeakAccumulator(PEAK_SAMPLE_RATE, PEAK_BIN_SECONDS, channels);
     proc.stdout?.on("data", (chunk: Buffer) => accumulatePeaks(acc, chunk));
     proc.on("close", (code) => {
+      if (code !== 0) {
+        reject(new Error(`ffmpeg failed decoding audio (exit ${code})`));
+        return;
+      }
       if (acc.frame === 0) {
-        reject(new Error(`ffmpeg produced no audio samples (exit ${code})`));
+        reject(new Error("ffmpeg produced no audio samples"));
         return;
       }
       resolvePromise(finishPeaks(acc));