## Summary
- Fix multipart uploads using form-data + node-fetch@2 +
fs.createReadStream() being truncated
- Convert old-style Node.js streams (that don't implement
`Symbol.asyncIterator`) to Web ReadableStreams before passing to native
fetch
## Test plan
- [x] New tests in `test/regression/issue/26225.test.ts` verify:
- Multipart uploads with form-data and createReadStream work correctly
- Async iterable bodies still work (regression test)
- Large file streams work correctly
- [x] Tests fail with `USE_SYSTEM_BUN=1` and pass with debug build
Fixes#26225🤖 Generated with [Claude Code](https://claude.com/claude-code)
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Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
