Parity with #2337's redeploy-tenants-on-staging.yml. Both prod and
staging redeploys now have explicit serialization:
group: redeploy-tenants-on-main (per-workflow, global)
group: redeploy-tenants-on-staging (per-workflow, global)
cancel-in-progress: false on both — aborting a half-rolled-out fleet
would leave tenants stuck on whatever image they happened to be on
when cancelled. Better to finish the in-flight rollout before starting
the next one.
Pre-fix this workflow relied on GitHub's implicit workflow_run queueing,
which is "probably fine" but not defensible — explicit > implicit for
load-bearing pipeline behavior. Picked up as a #2337 review nit
(architecture finding 1: concurrency asymmetry between the two
redeploy workflows).
No behavior change in the common case. The change matters only when
two main pushes land within seconds AND the first redeploy is still
mid-rollout — currently rare; will become more common once #2335
(staging-trigger publish) feeds main more frequently via auto-promote.