The fallback name was never checked against the names already taken, so an
entry called exactly what the fallback produces took the same file: `media/1/a:b.png`,
`media/2/a_b.png` and `media/3/2-a_b.png` extracted to five files for six
entries, the third overwriting the second, and both items' footage pointing at
it. Deduplication now runs on the name actually written and counts up until it
is free.
The collision predates making the names safe (two entries named `a_b.png` and
`2-a_b.png` collide on their own), but sanitising gives more ways in, so it
belongs with it.
Found by CodeRabbit on the pull request.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
EffectCraft writes its own templates as `media/<item id>/<file>` entries, and
extraction trusted both halves. `base_name` splits on `/` and `\`, but the item
id was taken with `split('/')` alone, and it is pasted in front of a base name
another item already used. So a second `media/..\..\..\Startup\x/clip.mp4`
entry became `<dir>/..\..\..\Startup\x-clip.mp4`, which on Windows is three
folders up, with the attacker choosing how the name ends.
The id is now used only when it is one, and the name goes through
`safe_file_name`: separators, drive colons and NUL become `_`, and `.` / `..`
become `footage`. Reached from `templates.create` with `path`, from File ▸ New
from Template, and from a template dropped in the user Templates folder.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
