A rollout no longer waits on a message that cannot arrive

When several processes start on a new version, one of them does the compile and the rest wait for it to finish. Waiting was the problem: they waited to be told, and the announcement is delivered only inside the process group that made it. A compile running in a separate group — the dedicated build job, or a portal in another cluster sharing the same database — finished, announced, and the waiting processes were never reached. Nothing ended the wait.

The same gap swallowed the other outcome too. A process that gives another one the job stays in the queue for it, so when the builder stopped — crashed, evicted mid-rollout — the job was handed straight to a process that had stopped listening. It held the job without doing it, and because it was alive and healthy nothing would ever take it away again. The next version could then never claim the build at all, and every portal on it stayed out of rotation waiting for a completion signal that no longer had an owner.

Waiting has been replaced by looking. The completion signal is a durable record, so a follower now reads it — the same record the build's own arbitration already decides on — instead of hoping to be notified. And it keeps watching for the job: being handed the build is now a real event that ends the wait. On being handed it, the follower re-reads the record — finished means stand down without repeating a compile that already happened, not finished means the previous builder went away and this one takes over. A follower that reaches its answer any other way now gives the job back rather than sitting on it.

No timer and no deadline were added. A deadline would end the wait by guessing, and a process that guesses "the compile finished" would report a version ready that it never checked.