repl_active_standby_count: registry truth (ep != NULL && !in_catch_up)
under r->lock. ha_state_t gains repl back-pointer (wired at init by
task 5.3); ha_has_write_quorum uses registry truth when wired, exact
legacy fallback when NULL; formula unchanged. Test 29 (wired gate,
catch-up-only standby → NOT_READY, admits after clear) captured RED
pre-fix. 29/29 group tests; suite at the 3-failure baseline.
Tests 21-28: repl_active_standby_count contract (5 RED vs inert -1
stub) + 3 gate-level pins (n_peers<=1 always-true, zero-connected
reject, stateless re-accept) that 4.2 must preserve. Declaration in
repl.h; ha.c/ha.h untouched (4.2 boundary). 28 tests / 5 RED; suite
at the 3-failure baseline with unchanged signatures.
Tests 17-20: catch-up ACK exclusion vs pending waiter, membership-change
wake of covered waiter, removal-below-majority fails at own deadline
(no forced early-fail), non-blocking bound. Landed GREEN: task 1.2's
commit_on_membership_change already implements the full 3.2 contract,
so RED was unachievable; reviewer confirmed mutation-killing power and
zero production changes. 20/20 group tests; suite at baseline.
commit_submit(WAIT): n_vcpus-relative admission cap with fast retriable
NOT_READY (admission-cap-only per corrected contract), CLOCK_REALTIME
timedwait loop on the per-LSN + gate predicate, post-timeout predicate
re-check, n_peers<=1 self-quorum through the single advancement site.
Inflight counter accurate under engine lock for the full blocking
interval with XCE_TESTING asserts. 16/16 group tests green unmodified;
full suite at the 3-failure baseline.
9 new cases (8-16): block-until-majority, deadline timeout, standalone
fast path, zero-ACK regression, n_vcpus-relative cap with floor, ACK
progress at saturation, gate as blocking predicate (NOT_READY is
admission-cap-only per corrected contract). Main-thread-only assertions
after joins; 16 tests / 9 RED failures; baseline unchanged.
