## Summary
- Fixes the entry point wrapper to distinguish between Server
configuration objects and already-running Server instances
- When a Server object from `Bun.serve()` is exported as the default
export, Bun no longer tries to call `Bun.serve()` on it again
## Root Cause
The entry point wrapper in `src/bundler/entry_points.zig` checks if the
default export has a `fetch` method to auto-start servers:
```javascript
if (typeof entryNamespace?.default?.fetch === 'function' || ...) {
const server = Bun.serve(entryNamespace.default);
}
```
However, `Server` objects returned from `Bun.serve()` also have a
`fetch` method (for programmatic request handling), so the wrapper
mistakenly tried to call `Bun.serve(server)` on an already-running
server.
## Solution
Added an `isServerConfig()` helper that checks:
1. The object has a `fetch` function or `app` property (config object
indicators)
2. The object does NOT have a `stop` method (Server instance indicator)
Server instances have `stop`, `reload`, `upgrade`, etc. methods, while
config objects don't.
## Test plan
- [x] Added regression test that verifies exporting a Server as default
export works without errors
- [x] Added test that verifies config objects with `fetch` still trigger
auto-start
- [x] Verified test fails with `USE_SYSTEM_BUN=1` and passes with the
fix
Fixes#26142🤖 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>
