Field traces (#16038, #11363) show Windows freeze storms driven by unbounded
concurrent git children (12+ at once, 50-65s status convoys for 25+ minutes).
Admit every main-process git child against atomic per-budget base+headroom
counters (general / network / per-route), with reserved interactive capacity,
ordering-only aging, close-bound permit release, a 120s fail-safe read timeout
that feeds scheduler backoff, tier plumbing through every option carrier, and
coalesced+jittered visibility pollers. Killswitch: ORCA_GIT_ADMISSION_DISABLED=1.
Storm harness A/B: max concurrent children 65 -> 6, interactive p95 791ms -> 88ms;
output-parity battery byte-identical with admission on vs off.
Brennan Benson