## Summary
- Fixes `ws.once()` only working on the first call for each event type
- The bug was in the `#onOrOnce` method which tracked native listeners
via a bitset but didn't account for `once` listeners auto-removing after
firing
- Now only persistent `on()` listeners set the bitset; `once()`
listeners always add new native handlers unless a persistent listener
already exists
## Test plan
- [x] Added regression test `test/regression/issue/26358.test.ts`
- [x] Test verifies `once('message')` works multiple times
- [x] Test verifies `once('pong')` works multiple times
- [x] Test verifies `on()` still works correctly
- [x] Test verifies mixing `on()` and `once()` works correctly
- [x] Verified test fails with `USE_SYSTEM_BUN=1` (bug exists)
- [x] Verified test passes with `bun bd test` (fix works)
Fixes#26358🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>
