ACTIVE_LABEL

const ACTIVE_LABEL: "shepherd:active" = "shepherd:active"

The drain stamps this label on an issue when it claims it (spawns an auto session) and keeps it through retire — a ready PR awaiting human merge is still “taken”. The SAME label is also stamped when a human links an issue at task creation (via the create route) and released when that session is archived, so a manually-linked issue is claimed too. It is the ONLY cross-instance coordination point: a second shepherd draining the same forge filters claimed issues out (see selectCandidates), so neither a second shepherd NOR the local drain takes an already-claimed issue (auto or manually-linked), and a retired-but-unmerged issue is not re-spawned. A constant (not the per-repo autoLabel) so every instance agrees on it without sharing config. The window is narrowed, not eliminated — two instances listing within the claim’s set-up latency can still race; local dedup then prevents a single instance double-spawning. Released only when the work is abandoned (manual archive, no merge); a human merge auto-closes the issue, retiring the claim with it.