The apiserver stayed circuit-breaker-degraded after a full controller
restart until manually restarted. Two root causes:
1. Breaker recovery was decoupled from the breaker itself. The breaker can
be tripped by a backend write failure (e.g. E_XCE_STANDBY -10014 while
the controller is electing) with no heartbeat ever failing, but
StartHeartbeat only recovered on a fail→success heartbeat transition
(prevFailed), so the breaker stayed degraded forever.
→ extract needsRejoinAfterHeartbeat(hbOK, prevFailed): recover when
prevFailed OR the breaker is currently tripped. 5 new unit tests.
2. The 30s heartbeat's fire-and-forget reconnect only fires when the lib's
internal ctx state is XCE_CTX_ERR. After a controller restart whose
election outlasts the FAILOVER_CALL retry budget, the retry loop's
xcecli_ctx_recover leaves the ctx RUN on a half-open connection, so the
FF path never reconnects and the client stays disconnected forever.
→ lib: new xcecli_force_reconnect() forces a rotate+recover regardless
of state; apiserver: 2s recoveryLoop force-reconnects + rejoins while
degraded.
Verified on cluster: after controller kill+restart, the apiserver logs
"backend re-joined controller after reconnect" and job submissions resume
without a manual restart; a fresh job runs to DONE. Controller, scheduler
(rejoin ok, bug-1513) and workers all auto-recover.
Co-Authored-By: Claude <noreply@anthropic.com>
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