Root cause of the 2026-04-24 all-day E2E failure chain: Railway staging
CP had TENANT_IMAGE pinned to :staging-a14cf86 — a static SHA that had
silently drifted 10+ days stale. Every new tenant (including every E2E
run's fresh tenant) was spawned with that stale image, which predated
applyRuntimeModelEnv. Without applyRuntimeModelEnv, HERMES_DEFAULT_MODEL
never reached the workspace EC2 user-data, so install.sh fell back to
nousresearch/hermes-4-70b → openrouter → 401 "Missing Authentication
header" in every A2A reply.
Four correct fixes shipped today all got shadowed by this single stale
pin:
• template-hermes#19 (provider priority for openai/*)
• template-hermes#20 (decouple prefix-strip from bridge guard)
• molecule-controlplane#247 (force fresh /opt/adapter clone)
• molecule-core#1987 (E2E pins HERMES_CUSTOM_* as workaround)
Fix: publish each main build under both :staging-<sha> AND :staging-latest.
Change Railway staging CP's TENANT_IMAGE env to :staging-latest (done via
`railway variables --set` as part of this incident). Future main builds
then auto-propagate to new tenant provisions without any human in the
loop.
Safety: :staging-latest is the "most recent main build" — NOT a
canary-verified promotion. That distinction is preserved:
• Prod tenants still pull :latest (canary-verified, retagged by
canary-verify.yml only after the canary fleet green-lights a digest)
• Staging tenants now pull :staging-latest (every main build, pre-canary)
So staging becomes the canary: if a :staging-latest build regresses,
the staging canary fleet catches it before it can be promoted to :latest
for prod. This is what the canary design intended; the missing
:staging-latest tag was the hole.
Zero impact on image size / build time: Docker tags point at the same
digest, no duplicate push.
Follow-up: filed an issue tracking the need for CP's TENANT_IMAGE to
NEVER be pinned to a SHA in any environment — it must always float on a
named tag (:staging-latest for staging, :latest for prod).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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