Build Coordinator

src/build/build_coordinator.rs

The build coordinator serializes rebuild requests, ensuring builds never run concurrently and that rapid file changes don't trigger redundant builds.

Coalescing

The coordinator implements a one-pending-build policy:

• If a build is running and a new trigger arrives, the trigger is noted as pending
• When the running build finishes, the pending build starts immediately
• Additional triggers that arrive while a build is running and one is already pending are discarded

This means at most two builds are ever queued: one running and one pending.

Error handling

Build failures are logged at warn level but do not exit the loop. The server continues running and serving the last successful build. Only channel closure exits the loop.

Reload signaling

After a successful build, a DevServerMessage::Reload is sent on the broadcast channel. After a failed build, a DevServerMessage::BuildError is sent, which the browser displays as an error overlay.