Layer (c) deploy-rollover config for the harness-workers fleet — pure
Railway config, no custom rolling-restart code. Declares overlapSeconds=45
(capacity floor: old deployment serves until new workers register+claim, so
no staleness dip) and drainingSeconds=180 (SIGTERM->SIGKILL window >=
PLATFORM_STOP_GRACE_MS so the layer-(b) 3s+90s composed worker-drain finishes)
for both prod and staging in the railway-envs SSOT, regenerates the JSON
snapshot, and extends the harness-workers drift gate so CI fails if either
field drifts between SSOT and snapshot. Documents both knobs, their rationale
(incl. that Railway's draining default is 0s = immediate SIGKILL), the
composition with drain layers a+b, and how to apply them (GraphQL
serviceInstanceUpdate / dashboard) in RAILWAY.md.
The harness-workers SSOT modeled only the top-level numReplicas, whose drift
gate watched a field that does not drive the live replica count. harness-workers
is single-region (us-west2); Railway derives the live count from
multiRegionConfig.us-west2.numReplicas.
- WorkerProvisioning gains effectiveReplicas (= multiRegionConfig.us-west2.
numReplicas), the authoritative field the drift gate now asserts. Top-level
numReplicas is retained as a documented mirror.
- Declared values reflect current reconciled reality (verified live via the
Railway GraphQL environment.config staged-config read): prod and staging both
at effectiveReplicas=6 (parity achieved by B-reconcile scaling prod 3 -> 6 in
both the top-level field and multiRegionConfig). BROWSER_POOL_MAX_CONTEXTS is
40 on both envs (verified live).
- Regenerated railway-envs.generated.json; drift-gate test asserts
effectiveReplicas (RED-GREEN proven). RAILWAY.md documents multiRegionConfig
as the effective knob and the achieved parity.
Add WorkerProvisioning interface and workerProvisioning field to the
harness-workers ServiceEntry in railway-envs.ts. Declares current live
reality: prod=3 replicas, staging=6 replicas, BROWSER_POOL_MAX_CONTEXTS=40
per worker (both envs).
Worker model: 1-worker-per-replica (Railway runs one process per
container, keyed on HOSTNAME). HARNESS_POOL_COUNT is informational
only — not a fork factor. Authoritative concurrency knob per worker is
BROWSER_POOL_MAX_CONTEXTS.
Comments flag: staging config-field drift (Railway field=2, live=6) as
a follow-up item; and the prod/staging parity decision (prod=3 vs
staging=6) as deliberately deferred.
Extends emit-railway-envs-json.ts to emit workerProvisioning into the
generated JSON snapshot. Adds drift-gate test
(harness-workers-provisioning.test.ts) that fails if SSOT numReplicas
diverges from the committed JSON snapshot — no live Railway API calls.
Red-green-red-green verified locally.
Updates RAILWAY.md with the 1-worker-per-replica model, declared
values, manual apply procedure, and drift-gate reference.
The existing tooling is verify-only for numReplicas; applying a replica
count change to Railway remains a manual operation (Railway Dashboard or
GraphQL API).
Mark