Remove the FN-8700 PR/file-claim blocking mechanism end to end (operator
decision after FN-8728 parked on unrelated PR #2398):
- Drop the AGENTS.md claim-check rule and scripts/check-file-claimed.mjs
- Executor prompt + fn_task_done no longer accept pr:N refs or treat open
PRs as blocked-exit reasons
- execution-block-classifier classifies on Fusion task dependencies only;
legacy pr refs are discarded, reason prose never makes a block durable
- Remove the session-log BLOCKED promotion and the gh-backed
reconcile-external-pr-blockers self-healing sweep
- Legacy file-claim parks are no longer honored, so previously PR-blocked
rows recover via normal paths
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Classify blocked exits so check-file-claimed / open-PR collisions never
auto-replan. Park failed with externalBlockers metadata (pr:N supported),
promote BLOCKED session logs instead of incomplete-step requeue, thrash-
exhaust after 3 identical durable blocks, and clear parks when gh reports
blocking PRs merged or closed.
