Forgejo's assignees PATCH is last-write-wins, so two dev agents polling
concurrently could both observe .assignee == null at the pre-check, both
PATCH, and the loser would silently "succeed" and proceed to implement
the same issue — colliding at the PR/branch stage.
Re-read the assignee after the PATCH and bail out if it isn't self.
Label writes are moved AFTER this verification so a losing claim leaves
no stray in-progress label to roll back.
Adds tests/lib-issue-claim.bats covering the three paths:
- happy path (single agent, re-read confirms self)
- lost race (re-read shows another agent — returns 1, no labels added)
- pre-check skip (initial GET already shows another agent)
Prerequisite for the LLAMA_BOTS parametric refactor that will run N
dev containers against the same project.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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