ci/github-script/check-target-branch: check staging-nixos mass rebuilds

Assisted-by: Codex gpt-5.6-sol medium

ci/github-script/check-target-branch-policy.test.ts

@@ -53,14 +53,14 @@ const cases: Array<{
     expected: 'mass-rebuild',
   },
   {
-    name: 'does not check mass rebuilds on staging-nixos',
+    name: 'flags a mass rebuild on staging-nixos',
     facts: { base: 'staging-nixos', maxRebuildCount: 24_000 },
-    expected: 'dismiss',
+    expected: 'mass-rebuild',
   },
   {
-    name: 'does not check mass rebuilds on a release staging-nixos branch',
+    name: 'flags a mass rebuild on a release staging-nixos branch',
     facts: { base: 'staging-nixos-26.05', maxRebuildCount: 1000 },
-    expected: 'dismiss',
+    expected: 'mass-rebuild',
   },
   {
     name: 'allows mass rebuilds on staging',
@@ -97,9 +97,9 @@ const cases: Array<{
     expected: 'dismiss',
   },
   {
-    name: 'does not check possible mass rebuilds on staging-nixos',
+    name: 'flags other possible mass rebuilds on staging-nixos',
     facts: { base: 'staging-nixos', maxRebuildCount: 500 },
-    expected: 'dismiss',
+    expected: 'possible-mass-rebuild',
   },
   {
     name: 'skips staging into master',
@@ -127,13 +127,13 @@ const cases: Array<{
     expected: 'skip-development-merge',
   },
   {
-    name: 'skips staging into staging-nixos',
+    name: 'checks staging into staging-nixos',
     facts: {
       base: 'staging-nixos',
       head: 'staging',
       maxRebuildCount: 24_000,
     },
-    expected: 'skip-development-merge',
+    expected: 'mass-rebuild',
   },
   {
     name: 'skips release staging-nixos into its release branch',
@@ -154,13 +154,13 @@ const cases: Array<{
     expected: 'skip-development-merge',
   },
   {
-    name: 'skips release staging into its staging-nixos branch',
+    name: 'checks release staging into its staging-nixos branch',
     facts: {
       base: 'staging-nixos-26.05',
       head: 'staging-26.05',
       maxRebuildCount: 24_000,
     },
-    expected: 'skip-development-merge',
+    expected: 'mass-rebuild',
   },
   {
     name: 'kernel exemption suppresses a possible mass rebuild',

ci/github-script/check-target-branch-policy.ts

@@ -1,4 +1,4 @@
-const { classify } = require('../supportedBranches.js')
+const { classify, split } = require('../supportedBranches.js')
 
 type TargetBranchPolicyFacts = {
   base: string
@@ -20,12 +20,17 @@ function getTargetBranchPolicy({ base, head }: { base: string; head: string }) {
   const baseClassification = classify(base)
   const headClassification = classify(head)
   const isPrimaryBase = baseClassification.type.includes('primary')
+  const isPrimaryHead = headClassification.type.includes('primary')
+  const isStagingNixosBase = split(base).prefix === 'staging-nixos'
+  const isDevelopmentHead = headClassification.type.includes('development')
   const shouldSkipDevelopmentMerge =
-    headClassification.type.includes('development')
+    isDevelopmentHead && (!isStagingNixosBase || isPrimaryHead)
 
   return {
+    isStagingNixosBase,
     shouldSkipDevelopmentMerge,
-    shouldCheckMassRebuild: !shouldSkipDevelopmentMerge && isPrimaryBase,
+    shouldCheckMassRebuild:
+      !shouldSkipDevelopmentMerge && (isPrimaryBase || isStagingNixosBase),
     shouldCheckNixosRebuild: !shouldSkipDevelopmentMerge && isPrimaryBase,
   }
 }
@@ -39,6 +44,7 @@ function decideTargetBranchReview({
   isExemptHomeAssistantUpdate,
 }: TargetBranchPolicyFacts): TargetBranchReviewDecision {
   const {
+    isStagingNixosBase,
     shouldSkipDevelopmentMerge,
     shouldCheckMassRebuild,
     shouldCheckNixosRebuild,
@@ -61,7 +67,11 @@ function decideTargetBranchReview({
     !isMassRebuild &&
     !isExemptKernelUpdate &&
     !isExemptHomeAssistantUpdate
-  if (shouldCheckMassRebuild && isPossibleMassRebuild) {
+  if (
+    shouldCheckMassRebuild &&
+    isPossibleMassRebuild &&
+    !(rebuildsAllTests && isStagingNixosBase)
+  ) {
     return 'possible-mass-rebuild'
   }
 

ci/github-script/check-target-branch.ts

@@ -53,10 +53,14 @@ type TargetBranchReviewFacts = {
   maxRebuildCount: number
 }
 
+function getStagingBranch(base: string) {
+  const version = split(base).version
+  return version ? `staging-${version}` : 'staging'
+}
+
 async function postMassRebuildReview(facts: TargetBranchReviewFacts) {
   const { github, context, core, dry, base, maxRebuildCount } = facts
-  const desiredBranch =
-    base === 'master' ? 'staging' : `staging-${split(base).version}`
+  const desiredBranch = getStagingBranch(base)
   const body = [
     `The PR's base branch is set to \`${base}\`, but this PR causes ${maxRebuildCount} rebuilds.`,
     'It is therefore considered a mass rebuild.',
@@ -107,8 +111,7 @@ async function postNixosRebuildReview(facts: TargetBranchReviewFacts) {
 
 async function postPossibleMassRebuildReview(facts: TargetBranchReviewFacts) {
   const { github, context, core, dry, base, maxRebuildCount } = facts
-  const stagingBranch =
-    base === 'master' ? 'staging' : `staging-${split(base).version}`
+  const stagingBranch = getStagingBranch(base)
   const body = [
     `The PR's base branch is set to \`${base}\`, and this PR causes ${maxRebuildCount} rebuilds.`,
     `Please consider whether this PR causes a mass rebuild according to [our conventions](https://github.com/NixOS/nixpkgs/blob/master/CONTRIBUTING.md#branch-conventions).`,