Disable auto-merge for unstable GitHub PRs (#7415)

Prevent enabling auto-merge when a PR is in an UNSTABLE merge state.
GitHub auto-merge mutations reject UNSTABLE PRs directly instead of
allowing them to wait, so we should suppress the option.

mobile/src/components/pr-sidebar/pr-auto-merge-availability.ts

@@ -15,6 +15,10 @@ function isConflicting(item: MobilePRAutoMergeAvailabilityInput): boolean {
   return item.mergeable === 'CONFLICTING' || item.mergeStateStatus === 'DIRTY'
 }
 
+function isUnstable(item: MobilePRAutoMergeAvailabilityInput): boolean {
+  return item.mergeStateStatus === 'UNSTABLE'
+}
+
 function hasReviewRequirement(item: MobilePRAutoMergeAvailabilityInput): boolean {
   return item.reviewDecision === 'REVIEW_REQUIRED' || item.reviewDecision === 'CHANGES_REQUESTED'
 }
@@ -27,7 +31,9 @@ function canMergeImmediately(item: MobilePRAutoMergeAvailabilityInput): boolean
 }
 
 function canRequestWhenReady(item: MobilePRAutoMergeAvailabilityInput): boolean {
-  if (item.state !== 'open' || isConflicting(item)) {
+  // Why: GitHub auto-merge waits on unmet requirements; UNSTABLE is rejected
+  // by the mutation rather than becoming a waitable auto-merge request.
+  if (item.state !== 'open' || isConflicting(item) || isUnstable(item)) {
     return false
   }
   if (item.mergeQueueRequired === true) {

src/renderer/src/components/github-pr-merge-state.test.ts

@@ -62,6 +62,18 @@ describe('presentGitHubPRMergeState', () => {
     })
   })
 
+  it('does not offer enable auto-merge for GitHub unstable PRs', () => {
+    expect(
+      presentGitHubPRMergeState(
+        pr({
+          mergeable: 'UNKNOWN',
+          mergeStateStatus: 'UNSTABLE',
+          checksSummary: { state: 'failure', total: 1, passed: 0, failed: 1, pending: 0 }
+        })
+      ).autoMergeAction
+    ).toBeNull()
+  })
+
   it('does not offer enable auto-merge on conflicting PRs (GitHub would reject it)', () => {
     expect(
       presentGitHubPRMergeState(pr({ mergeable: 'CONFLICTING', mergeStateStatus: 'DIRTY' }))

src/shared/github-pr-auto-merge-availability.test.ts

@@ -48,7 +48,7 @@ describe('github PR auto-merge availability', () => {
     expect(canShowGitHubPRAutoMergeControl(pr({ autoMergeEnabled: true }))).toBe(true)
   })
 
-  it('suppresses closed, draft, disallowed, and conflicting PRs', () => {
+  it('suppresses closed, draft, disallowed, conflicting, and unstable PRs', () => {
     expect(
       canShowGitHubPRAutoMergeControl(pr({ state: 'draft', mergeStateStatus: 'BLOCKED' }))
     ).toBe(false)
@@ -63,5 +63,11 @@ describe('github PR auto-merge availability', () => {
     expect(
       canShowGitHubPRAutoMergeControl(pr({ mergeable: 'CONFLICTING', mergeStateStatus: 'DIRTY' }))
     ).toBe(false)
+    expect(
+      canEnableGitHubPRAutoMerge(pr({ mergeable: 'UNKNOWN', mergeStateStatus: 'UNSTABLE' }))
+    ).toBe(false)
+    expect(
+      canShowGitHubPRAutoMergeControl(pr({ mergeable: 'UNKNOWN', mergeStateStatus: 'UNSTABLE' }))
+    ).toBe(false)
   })
 })

src/shared/github-pr-auto-merge-availability.ts

@@ -18,6 +18,10 @@ function isConflicting(item: GitHubPRAutoMergeAvailabilityInput): boolean {
   return item.mergeable === 'CONFLICTING' || item.mergeStateStatus === 'DIRTY'
 }
 
+function isUnstable(item: GitHubPRAutoMergeAvailabilityInput): boolean {
+  return item.mergeStateStatus === 'UNSTABLE'
+}
+
 function hasReviewRequirement(item: GitHubPRAutoMergeAvailabilityInput): boolean {
   return item.reviewDecision === 'REVIEW_REQUIRED' || item.reviewDecision === 'CHANGES_REQUESTED'
 }
@@ -30,7 +34,9 @@ function canMergeImmediately(item: GitHubPRAutoMergeAvailabilityInput): boolean
 }
 
 function canRequestWhenReady(item: GitHubPRAutoMergeAvailabilityInput): boolean {
-  if (!isOpenPR(item) || isConflicting(item)) {
+  // Why: GitHub auto-merge waits on unmet requirements; UNSTABLE is rejected
+  // by the mutation rather than becoming a waitable auto-merge request.
+  if (!isOpenPR(item) || isConflicting(item) || isUnstable(item)) {
     return false
   }
   if (item.mergeQueueRequired === true) {