Confirm connector thread is isolated from worker_process_update() (main
thread) and resource_sync_thread() (own thread) via code read plus a real
pthread concurrency test. Add unit and live 3-node E2E coverage for
candidate/reconnect behavior, all-candidates-unreachable diagnostics, and
liveness cadence under concurrent reconnect.
The E2E run surfaced two production bugs the 2.1/2.2 unit tests missed:
xcecli_start() resets the reconnect callback to NULL after it runs, so
registering it before xcecli_start() silently no-ops the whole rejoin
mechanism; and a successful worker join returns its assigned slot index
as reply.status (any rc >= 0), not always exactly 0, so checking_connection()'s
rc == 0 success check never fired on a real non-zero-slot join. Both fixed,
plus per-candidate names added to the all-unreachable failure log.
Root-check bypass needed for the E2E run is gated at compile time via the
existing VIRTUAL_CLUSTER flag, not a runtime env var, so the real xcecd
binary's root requirement has zero bypass surface.
Rongsong Shen
619b119ef5
