add-video/add-audio: silent skip on filename collision in assets dir (no warning)

[naoyashiga]

Summary

addVideo (and likely addAudio) in src/factory.ts copies source files into
assets/video/<basename> using only the file's basename, and skips the copy
if the destination already exists:

const filename = basename(opts.path) || "media";
const destPath = resolve(assetsDir, filename);
if (!existsSync(destPath)) {
  copyFileSync(opts.path, destPath);
}

If two different source files share the same basename (e.g. en/0_00.png
and jp/0_00.png), the second one added is silently skipped — the draft
ends up pointing at the wrong file's content, with no error or warning.

Expected behavior

I understand the reasoning behind skipping the copy when the destination
already exists (avoids redundant copies). But when the skip happens because
of a different source file resolving to the same destination filename,
the CLI should print a warning to the console, e.g.:

Warning: "assets/video/0_00.png" already exists from a different source
file; skipping copy. The draft may reference stale content.

This would make the collision visible instead of silently producing a
draft with the wrong media.

Repro

1. capcut add-video <project> path/to/jp/0_00.png 0s 7s
2. capcut add-video <project> path/to/en/0_00.png 0s 7s
3. The second segment's material ends up pointing at the jp image content,
   with no warning printed.

[renezander030]

Thanks — great catch, and you're right that it hits addAudio too, not just addVideo.

One nuance on the fix: the skip-on-exists is intentional (the Wikimedia fetch path pre-writes into assets/<kind> so the later copy is a deliberate no-op, and re-adding the same file mustn't re-copy). So rather than warn-only — which surfaces the collision but still leaves the draft pointing at stale content — I made it content-aware:

• existing file is byte-identical → keep the silent no-op
• a different source resolving to the same basename → write it under a content-hashed name (0_00.<sha1-8>.png) and warn on stderr

That way the draft ends up referencing the correct content, not just flagged.

Fix + tests in #38. Thanks again for the precise repro and code pointer — made this a quick one.

[naoyashiga]

Thank you for the quick fix!

[renezander030]

No worries. This is a team effort. Bring in patches as you spot them!