TestPromoteQueuedWhileRequiresActionMixedTools has flaked three times across
Windows and Ubuntu CI runners since 2026-05-06; local repro on the dev
workspace has not surfaced it. The May 8 Ubuntu log shows all four
PromoteQueued post-TX pubsub publishes reaching pg_notify, yet the test still
times out 25s later, so the failure is downstream between the subscriber's
listener and the test's events channel. Adds three Debug-level markers in
chatd.go (no logic change) plus two t.Logf markers in the test's reader so
the next CI occurrence pins down exactly which step failed.
Closes ENG-2645
Closescoder/internal#1523