server: report serving revision in readiness for origin drift checks

server/src/controllers/auxiliary.effect.test.ts

@@ -121,6 +121,7 @@ const healthy = (): HealthHttpResponse => ({
   ok: true,
   status: "ok",
   timestamp: 1_784_320_000,
+  revision: "0123456789abcdef0123456789abcdef01234567",
   draining: false,
   checks: {
     database: {
@@ -753,6 +754,7 @@ describe("AuxiliaryRouteGroup", () => {
       ok: false,
       status: "degraded",
       timestamp: 1_784_320_001,
+      revision: "0123456789abcdef0123456789abcdef01234567",
       draining: true,
       checks: {
         database: {

server/src/controllers/health.effect.ts

@@ -77,6 +77,7 @@ export const HealthHttpResponseSchema = Schema.Struct({
   ok: Schema.Boolean,
   status: Schema.Literals(["ok", "degraded"]),
   timestamp: UnixSeconds,
+  revision: Schema.String,
   draining: Schema.Boolean,
   checks: Schema.Struct({
     database: DatabaseHealth,

server/src/controllers/healthCheck.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, it } from "bun:test"
+import { gitCommitSha } from "@in/server/buildEnv"
 import { InlineProtocolClock } from "@in/server/modules/inlineProtocol/clockHealth"
 import { combineHealthProbes } from "@in/server/db/connectionPolicy"
 import { makeHealthChecker, runHealthChecks, withLifecycleCheck } from "./healthCheck"
@@ -238,11 +239,14 @@ describe("shared readiness database probe", () => {
       checkBroker: () => brokerReady,
     })
     const lifecycle = { getShutdownState: () => ({ shuttingDown, signal: "SIGTERM" as const, startedAtMs: wall }) }
-    expect(withLifecycleCheck(await check(), lifecycle).ok).toBe(true)
+    const ready = withLifecycleCheck(await check(), lifecycle)
+    expect(ready.ok).toBe(true)
+    // Monitors compare origins by the serving build's source commit.
+    expect(ready.revision).toBe(gitCommitSha)
     brokerReady = false
     shuttingDown = true
     const draining = withLifecycleCheck(await check(), lifecycle)
-    expect(draining).toMatchObject({ draining: true, ok: false, checks: { database: { ok: true }, broker: { ok: false } } })
+    expect(draining).toMatchObject({ draining: true, ok: false, revision: gitCommitSha, checks: { database: { ok: true }, broker: { ok: false } } })
     shuttingDown = false
     monotonic = 500
     wall += 21_000

server/src/controllers/healthCheck.ts

@@ -1,3 +1,4 @@
+import { gitCommitSha } from "@in/server/buildEnv"
 import {
   checkDatabaseHealth,
 } from "@in/server/db"
@@ -51,6 +52,8 @@ export interface HealthResponse {
 }
 
 export interface HealthHttpResponse extends HealthResponse {
+  /** Source commit of the serving build, so monitors can detect origin version drift. */
+  readonly revision: string
   readonly draining: boolean
   readonly checks: HealthResponse["checks"] & {
     readonly lifecycle: {
@@ -299,6 +302,7 @@ export const withLifecycleCheck = (
   if (liveness.ok) {
     return {
       ...result,
+      revision: gitCommitSha,
       draining: false,
       checks: {
         ...result.checks,
@@ -309,6 +313,7 @@ export const withLifecycleCheck = (
 
   return {
     ...result,
+    revision: gitCommitSha,
     ok: false,
     status: "degraded",
     draining: true,