fix(ci): release gate no longer fails when a merge cancels main's CI run

scripts/verify-release-ci.test.ts

@@ -0,0 +1,74 @@
+import { assert, it } from "@effect/vitest";
+
+import { evaluateRequiredChecks } from "./verify-release-ci.ts";
+
+const CHECK = "Format, Lint, Typecheck, Test, Build";
+
+// A merge landing on main cancels the previous main CI run. The merge queue
+// already passed the same checks on that exact commit, so the release gate
+// must fall through to that verdict instead of failing on the cancellation.
+it("a cancelled newer run yields to an older passing run of the same check", () => {
+  const evaluation = evaluateRequiredChecks(
+    [CHECK],
+    [
+      {
+        name: CHECK,
+        status: "completed",
+        conclusion: "success",
+        completed_at: "2026-09-06T09:11:40Z",
+        html_url: "https://example.test/merge-queue",
+      },
+      {
+        name: CHECK,
+        status: "completed",
+        conclusion: "cancelled",
+        completed_at: "2026-09-06T09:14:50Z",
+        html_url: "https://example.test/main-push",
+      },
+    ],
+  );
+
+  assert.deepEqual(evaluation.failures, []);
+  assert.deepEqual(evaluation.pending, []);
+  assert.equal(evaluation.checksByName.get(CHECK)?.html_url, "https://example.test/merge-queue");
+});
+
+it("a newer run still in progress is waited on even when an older run passed", () => {
+  const evaluation = evaluateRequiredChecks(
+    [CHECK],
+    [
+      {
+        name: CHECK,
+        status: "completed",
+        conclusion: "success",
+        completed_at: "2026-09-06T09:11:40Z",
+      },
+      {
+        name: CHECK,
+        status: "in_progress",
+        conclusion: null,
+        started_at: "2026-09-06T09:12:00Z",
+      },
+    ],
+  );
+
+  assert.deepEqual(evaluation.failures, []);
+  assert.equal(evaluation.pending.length, 1);
+});
+
+it("a check whose only run was cancelled still fails the gate", () => {
+  const evaluation = evaluateRequiredChecks(
+    [CHECK],
+    [
+      {
+        name: CHECK,
+        status: "completed",
+        conclusion: "cancelled",
+        completed_at: "2026-09-06T09:14:50Z",
+      },
+    ],
+  );
+
+  assert.equal(evaluation.failures.length, 1);
+  assert.deepEqual(evaluation.pending, []);
+});

scripts/verify-release-ci.ts

@@ -154,13 +154,27 @@ function formatCheckRunStatus(checkName: string, checkRun: CheckRun | undefined)
   return `${checkName}: status=${checkRun.status ?? "unknown"}, conclusion=${checkRun.conclusion ?? "unknown"} (${checkRun.html_url ?? checkRun.details_url ?? "no URL"})`;
 }
 
-function evaluateRequiredChecks(
+function isCancelled(checkRun: CheckRun): boolean {
+  return checkRun.status === "completed" && checkRun.conclusion === "cancelled";
+}
+
+/**
+ * Picks the newest run of each required check and grades it. A cancelled run
+ * is not a verdict on the commit, so it yields to the newest run that has one:
+ * a merge landing on main cancels the previous main CI run, but the merge
+ * queue already ran the same checks on that exact commit.
+ */
+export function evaluateRequiredChecks(
   requiredChecks: ReadonlyArray<string>,
   checkRuns: ReadonlyArray<CheckRun>,
 ): CheckRunEvaluation {
   const checksByName = new Map<string, CheckRun>();
-  for (const checkRun of checkRuns) {
-    if (checkRun.name && !checksByName.has(checkRun.name)) {
+  for (const checkRun of [...checkRuns].sort(compareCheckRuns)) {
+    if (!checkRun.name) {
+      continue;
+    }
+    const current = checksByName.get(checkRun.name);
+    if (!current || (isCancelled(current) && !isCancelled(checkRun))) {
       checksByName.set(checkRun.name, checkRun);
     }
   }
@@ -196,8 +210,7 @@ async function fetchRequiredGithubActionCheckRuns({
   const requiredCheckSet = new Set(requiredChecks);
   return (await fetchCheckRuns(repository, ref, token))
     .filter((run) => requiredCheckSet.has(run.name ?? ""))
-    .filter((run) => !run.app?.slug || run.app.slug === "github-actions")
-    .sort(compareCheckRuns);
+    .filter((run) => !run.app?.slug || run.app.slug === "github-actions");
 }
 
 async function waitForRequiredChecks({
@@ -296,4 +309,6 @@ async function main(): Promise<void> {
   console.log(`Required CI checks passed for ${ref}.`);
 }
 
-await main();
+if (import.meta.main) {
+  await main();
+}