#2000 fixed one symptom — TENANT_IMAGE pinned to `staging-a14cf86`
(10 days stale) silently no-op'd four upstream fixes on 2026-04-24.
This adds the audit pattern as a re-runnable script so the broader
class is observable on demand without new CI infrastructure.
Audit results today (2026-04-27):
controlplane / production: 54 vars audited, 0 drift-prone pins
controlplane / staging: 52 vars audited, 0 drift-prone pins
So the immediate audit deliverable is clean — TENANT_IMAGE is the only
known violation and #2000 already fixed it. The script makes the
ongoing audit a 5-second command instead of a manual one.
Detection regex catches:
* branch-SHA suffixes (`staging|main|prod|production-<6+ hex>`)
— the exact 2026-04-24 incident shape
* version pins after `:` or `=` (`:v1.2.3`, `=v0.1.16`)
— same drift class, just rendered differently
Anchoring on `:` or `=` keeps prose like "version 1.2.3 of the api"
out of the false-positive set. UUIDs, ARNs, AMI IDs, secrets, and
floating tags (`:staging-latest`, `:main`) pass through untouched.
Regression test (tests/ops/test_audit_railway_sha_pins.sh) pins 20
representative cases — 9 should-flag (covering all four branch
prefixes + semver variants + middle-of-value matches) and 11
should-pass (the false-positive guards). Same regex inlined in both
files so a future tweak that weakens detection fails the test in
lockstep with weakening the audit.
Both files shellcheck clean.
CI gate (acceptance criterion's "regression: add a CI check") is
deliberately scoped out — querying Railway from CI requires plumbing
RAILWAY_TOKEN as a repo secret, which is multi-step setup. The
re-runnable script + test cover the same surface today; the CI
workflow is a small follow-up once the token is provisioned.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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