## Summary
- Fixes#25903 - `Bun.write()` mode option ignored when copying from
`Bun.file()`
- The destination file now correctly uses the specified `mode` option
instead of default permissions
- Works on Linux (via open flags), macOS (chmod after clonefile), and
Windows (chmod after copyfile)
## Test plan
- [x] Added regression test in `test/regression/issue/25903.test.ts`
- [x] Test passes with `bun bd test test/regression/issue/25903.test.ts`
- [x] Test fails with `USE_SYSTEM_BUN=1 bun test
test/regression/issue/25903.test.ts` (verifies the bug exists)
## Changes
- `src/bun.js/webcore/Blob.zig`: Add `mode` field to `WriteFileOptions`
and parse from options
- `src/bun.js/webcore/blob/copy_file.zig`: Use `destination_mode` in
`CopyFile` struct and `doOpenFile`
- `packages/bun-types/bun.d.ts`: Add `mode` option to BunFile copy
overloads
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
