From a164f42b8aa19cd6fc7ee75c7ab1e7aadf517a32 Mon Sep 17 00:00:00 2001
From: Neil <4138956+nwparker@users.noreply.github.com>
Date: Thu, 22 Oct 2026 01:39:19 -0700
Subject: [PATCH] fix(ci): exclude inherited job results from runner demand
 (#31919)

---
 config/scripts/ci-job-executions.mjs      | 24 ++++++++++++++
 config/scripts/ci-runner-demand.mjs       |  2 +-
 config/scripts/ci-runner-metrics.mjs      |  7 ++--
 config/scripts/ci-runner-metrics.test.mjs | 40 +++++++++++++++++++++++
 4 files changed, 70 insertions(+), 3 deletions(-)
 create mode 100644 config/scripts/ci-job-executions.mjs

diff --git a/config/scripts/ci-job-executions.mjs b/config/scripts/ci-job-executions.mjs
new file mode 100644
index 00000000000..e2575312e00
--- /dev/null
+++ b/config/scripts/ci-job-executions.mjs
@@ -0,0 +1,24 @@
+const executionKey = (job) =>
+  job.name &&
+  job.runner_name &&
+  job.started_at &&
+  job.completed_at &&
+  Number.isSafeInteger(job.run_attempt) &&
+  job.run_attempt > 0
+    ? JSON.stringify([job.name, job.runner_name, job.started_at, job.completed_at])
+    : null
+
+export function jobExecutions(jobs) {
+  const firstAttempt = new Map()
+  // Failed-only retries copy completed jobs with new IDs and the original execution timestamps.
+  for (const job of jobs) {
+    const key = executionKey(job)
+    if (key !== null) {
+      firstAttempt.set(key, Math.min(firstAttempt.get(key) ?? Infinity, job.run_attempt))
+    }
+  }
+  return jobs.filter((job) => {
+    const key = executionKey(job)
+    return key === null || firstAttempt.get(key) === job.run_attempt
+  })
+}
diff --git a/config/scripts/ci-runner-demand.mjs b/config/scripts/ci-runner-demand.mjs
index 6f1f39ad0b7..0a60d1f40f6 100644
--- a/config/scripts/ci-runner-demand.mjs
+++ b/config/scripts/ci-runner-demand.mjs
@@ -78,7 +78,7 @@ export function demandMarkdown(report) {
         `| ${row.workflow} | ${row.runs} | ${(row.runnerMinutes / 60).toFixed(1)} | ${(row.cancelledRunnerMinutes / 60).toFixed(1)} | ${(row.repeatedSuccessfulRunnerMinutes / 60).toFixed(1)} | ${row.runnerMinutesPerCompletedPrRun?.toFixed(1) ?? '—'} |`
     ),
     '',
-    'Repeated green-job hours count assigned, completed jobs with a successful job of the same name in an earlier attempt of that run. This is a review bucket, not guaranteed avoidable work; it overlaps total and cancelled-run hours.',
+    'Completed records with the same job name, runner and execution timestamps across attempts are counted once: GitHub carries successful results forward without running them again. Repeated green-job hours count fresh executions after a successful job of the same name in an earlier attempt. This review bucket is not guaranteed avoidable work; it overlaps total and cancelled-run hours.',
     '',
     '| Runner labels | Hours | Queue/provisioning p95 minutes |',
     '| --- | ---: | ---: |',
diff --git a/config/scripts/ci-runner-metrics.mjs b/config/scripts/ci-runner-metrics.mjs
index 2e7a580eb0b..917711c6d7d 100644
--- a/config/scripts/ci-runner-metrics.mjs
+++ b/config/scripts/ci-runner-metrics.mjs
@@ -1,3 +1,5 @@
+import { jobExecutions } from './ci-job-executions.mjs'
+
 const minutesBetween = (start, end) => {
   const value = (Date.parse(end) - Date.parse(start)) / 60_000
   return Number.isFinite(value) ? Math.max(0, value) : 0
@@ -42,8 +44,9 @@ export function runnerDemand(runs, samples) {
   for (const { run, jobs, weight } of samples) {
     const row = workflows.get(workflowKey(run))
     row.sampledRuns++
+    const executions = jobExecutions(jobs)
     const firstSuccess = new Map()
-    for (const job of jobs) {
+    for (const job of executions) {
       if (job.name && Number.isInteger(job.run_attempt) && job.conclusion === 'success') {
         firstSuccess.set(
           job.name,
@@ -51,7 +54,7 @@ export function runnerDemand(runs, samples) {
         )
       }
     }
-    for (const job of jobs) {
+    for (const job of executions) {
       if (!job.runner_name || !job.started_at) {
         continue
       }
diff --git a/config/scripts/ci-runner-metrics.test.mjs b/config/scripts/ci-runner-metrics.test.mjs
index 3f9a766f483..6c86d090129 100644
--- a/config/scripts/ci-runner-metrics.test.mjs
+++ b/config/scripts/ci-runner-metrics.test.mjs
@@ -79,6 +79,10 @@ it('paginates jobs and bounds run discovery to 24 complete hours', async () => {
 it('counts only later attempts of previously successful jobs, including failed repeats', () => {
   const observation = (name, run_attempt, conclusion, extra = {}) => ({
     ...job,
+    started_at: new Date(Date.parse(job.started_at) + (run_attempt ?? 0) * 600_000).toISOString(),
+    completed_at: new Date(
+      Date.parse(job.completed_at) + (run_attempt ?? 0) * 600_000
+    ).toISOString(),
     name,
     run_attempt,
     conclusion,
@@ -115,6 +119,42 @@ it('counts only later attempts of previously successful jobs, including failed r
   expect(report.incompleteJobs).toBe(1)
 })
 
+it('counts carried-forward results once while retaining fresh executions on the same runner', () => {
+  const first = { ...job, id: 1, name: 'unit', run_attempt: 1, conclusion: 'success' }
+  const carried = { ...first, id: 2, run_attempt: 2 }
+  const fresh = {
+    ...first,
+    id: 3,
+    run_attempt: 3,
+    started_at: '2026-09-27T00:23:00Z',
+    completed_at: '2026-09-27T00:28:00Z'
+  }
+  const failed = { ...first, id: 5, name: 'build', conclusion: 'failure' }
+  const report = runnerDemand(
+    [run],
+    [
+      {
+        run,
+        weight: 2,
+        jobs: [
+          { ...fresh, id: 4, run_attempt: 4 },
+          carried,
+          first,
+          fresh,
+          failed,
+          { ...failed, id: 6, run_attempt: 2 }
+        ]
+      }
+    ]
+  )
+  expect(report.workflows[0]).toMatchObject({
+    runnerMinutes: 30,
+    repeatedSuccessfulJobs: 2,
+    repeatedSuccessfulRunnerMinutes: 10
+  })
+  expect(report.pools[0].runnerMinutes).toBe(30)
+})
+
 it('refuses to publish a silently truncated inventory', async () => {
   await expect(
     collectRunnerDemand({}, async () => ({ total_count: 1001, workflow_runs: [] }))