Documents why self-healing force-removed a worktree a planning session was
using and parked the card branch-conflict-unrecoverable: planning gained a task
worktree but never took an active-session lease, so the reclaim sweep's liveness
guard had nothing to see, and a zero-commit branch classifies as
tip-already-merged by construction.
Captures the investigation's dead ends too — including reading maxConcurrent
from a multi-tenant config table without filtering by project_id, which produced
a confidently wrong root cause — and the three ways the first version of the fix
was itself wrong.
CONCEPTS.md: adds planning to the Active-session lease kinds (the entry had gone
stale), states the converse invariant that an unheld path reads as proof nothing
is running, and defines Top-level agent slot — the capacity concept whose
conflation with the worktree limit derailed the first hour of diagnosis.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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