fix(engine): resolve root-absolute media from project (#2399)

packages/engine/src/services/audioMixer.test.ts

@@ -438,6 +438,38 @@ describe("processCompositionAudio", () => {
     const prepareArgs = runFfmpegMock.mock.calls[0]?.[0];
     expect(prepareArgs).toContain(join(baseDir, "assets", filename));
   });
+
+  it("prepares browser root-absolute audio srcs from the project root", async () => {
+    const baseDir = mkdtempSync(join(tmpdir(), "hf-audio-base-"));
+    const workDir = mkdtempSync(join(tmpdir(), "hf-audio-work-"));
+    tempDirs.push(baseDir, workDir);
+
+    mkdirSync(join(baseDir, ".media"), { recursive: true });
+    writeFileSync(join(baseDir, ".media", "tone.wav"), "stub");
+
+    const result = await processCompositionAudio(
+      [
+        {
+          id: "tone",
+          src: "/.media/tone.wav",
+          start: 0,
+          end: 1,
+          mediaStart: 0,
+          layer: 0,
+          volume: 1,
+          type: "audio",
+        },
+      ],
+      baseDir,
+      workDir,
+      join(baseDir, "out.m4a"),
+      1,
+    );
+
+    expect(result.success).toBe(true);
+    expect(result.error).toBeUndefined();
+    expect(runFfmpegMock.mock.calls[0]?.[0]).toContain(join(baseDir, ".media", "tone.wav"));
+  });
 });
 
 describe("parseAudioElements — relative data-start resolution", () => {

packages/engine/src/services/audioMixer.ts

@@ -5,7 +5,7 @@
  */
 
 import { closeSync, existsSync, mkdirSync, mkdtempSync, openSync, rmSync, writeFileSync } from "fs";
-import { isAbsolute, join, dirname } from "path";
+import { join, dirname } from "path";
 import { parseHTML } from "linkedom";
 import { extractAudioMetadata } from "../utils/ffprobe.js";
 import { downloadToTemp, isHttpUrl } from "../utils/urlDownloader.js";
@@ -530,7 +530,7 @@ export async function processCompositionAudio(
       }
       try {
         let srcPath = element.src;
-        if (!isAbsolute(srcPath) && !isHttpUrl(srcPath)) {
+        if (!isHttpUrl(srcPath)) {
           // Same browser-vs-filesystem path semantics as videos — see
           // resolveProjectRelativeSrc in videoFrameExtractor for the full why.
           srcPath = resolveProjectRelativeSrc(element.src, baseDir, compiledDir);

packages/engine/src/services/videoFrameExtractor.test.ts

@@ -143,6 +143,13 @@ describe("resolveProjectRelativeSrc — sub-composition path clamping", () => {
     );
   });
 
+  it("resolves a browser root-absolute URL from the project root", () => {
+    const projectDir = join(tmp, "project");
+    expect(resolveProjectRelativeSrc("/assets/foo.mp4", projectDir)).toBe(
+      join(projectDir, "assets/foo.mp4"),
+    );
+  });
+
   it("clamps a leading `../` so `../assets/foo.mp4` resolves to assets/foo.mp4", () => {
     const projectDir = join(tmp, "project");
     expect(resolveProjectRelativeSrc("../assets/foo.mp4", projectDir)).toBe(

packages/engine/src/services/videoFrameExtractor.ts

@@ -670,6 +670,12 @@ export function resolveProjectRelativeSrc(
 ): string {
   const qIdx = src.indexOf("?");
   const cleanSrc = qIdx >= 0 ? src.slice(0, qIdx) : src;
+
+  // Preserve explicit filesystem paths when they really exist. Otherwise a
+  // leading slash is a browser origin-root URL (`/assets/foo.mp4`), which the
+  // file server serves from the project root rather than the host filesystem.
+  if (isAbsolute(cleanSrc) && existsSync(cleanSrc)) return cleanSrc;
+
   const candidates: string[] = [];
 
   const addCandidate = (candidate: string): void => {
@@ -746,11 +752,7 @@ export async function extractAllVideoFrames(
     if (signal?.aborted) break;
     try {
       let videoPath = video.src;
-      // Use isAbsolute() rather than startsWith("/"). On Windows, absolute paths
+      if (!isHttpUrl(videoPath)) {
-      // like "C:\…" are not detected by the latter, so we'd re-join them under
-      // baseDir and produce duplicated, nonexistent paths
-      // (e.g. C:\tmp\hf-vfr-test-X\C:\tmp\hf-vfr-test-X\vfr_screen.mp4).
-      if (!isAbsolute(videoPath) && !isHttpUrl(videoPath)) {
         videoPath = resolveProjectRelativeSrc(video.src, baseDir, compiledDir);
       }