## Summary
- Fixes silent 401 Unauthorized errors when using proxies with long
passwords (e.g., JWT tokens > 4096 chars)
- Bun was silently dropping proxy passwords exceeding 4095 characters,
falling through to code that only encoded the username
## Changes
- Added `PercentEncoding.decodeWithFallback` which uses a 4KB stack
buffer for the common case and falls back to heap allocation only for
larger inputs
- Updated proxy auth encoding in `AsyncHTTP.zig` to use the new fallback
method
## Test plan
- [x] Added test case that verifies passwords > 4096 chars are handled
correctly
- [x] Test fails with system bun (v1.3.3), passes with this fix
- [x] All 29 proxy tests pass
🤖 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>
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