fix(web): the default-branch dialog no longer offers a feature branch it cannot create

apps/web/src/components/GitActionsControl.logic.test.ts

@@ -8,6 +8,7 @@ import {
   requiresDefaultBranchConfirmation,
   resolveAutoFeatureBranchName,
   resolveDefaultBranchActionDialogCopy,
+  resolveFeatureBranchUnavailableReason,
   resolveGitActionProgressPresentation,
   resolveGitActionResultToastTiming,
   resolveLiveThreadBranchUpdate,
@@ -1025,6 +1026,21 @@ describe("resolveDefaultBranchActionDialogCopy", () => {
   });
 });
 
+describe("resolveFeatureBranchUnavailableReason", () => {
+  it("blocks the feature branch when there is nothing to commit", () => {
+    assert.equal(
+      resolveFeatureBranchUnavailableReason({ branchName: "main", hasWorkingTreeChanges: false }),
+      "There are no changes to commit, so a feature branch can't be named. Create a branch yourself or continue on main.",
+    );
+  });
+
+  it("allows the feature branch when there are changes to commit", () => {
+    assert.isNull(
+      resolveFeatureBranchUnavailableReason({ branchName: "main", hasWorkingTreeChanges: true }),
+    );
+  });
+});
+
 describe("buildGitActionProgressStages", () => {
   it("shows only push progress for explicit push actions", () => {
     const stages = buildGitActionProgressStages({

apps/web/src/components/GitActionsControl.logic.ts

@@ -432,6 +432,18 @@ export function resolveDefaultBranchActionDialogCopy(input: {
   };
 }
 
+/**
+ * Why the default-ref dialog cannot check out a feature branch, or null when it can.
+ * The server names that branch from the uncommitted changes, so a clean tree cannot use it.
+ */
+export function resolveFeatureBranchUnavailableReason(input: {
+  branchName: string;
+  hasWorkingTreeChanges: boolean;
+}): string | null {
+  if (input.hasWorkingTreeChanges) return null;
+  return `There are no changes to commit, so a feature branch can't be named. Create a branch yourself or continue on ${input.branchName}.`;
+}
+
 export function resolveThreadBranchUpdate(
   result: GitRunStackedActionResult,
 ): { branch: string } | null {

apps/web/src/components/GitActionsControl.tsx

@@ -60,6 +60,7 @@ import {
   type DefaultBranchConfirmableAction,
   requiresDefaultBranchConfirmation,
   resolveDefaultBranchActionDialogCopy,
+  resolveFeatureBranchUnavailableReason,
   resolveGitActionProgressPresentation,
   resolveGitActionResultToastTiming,
   resolveLiveThreadBranchUpdate,
@@ -1224,6 +1225,15 @@ export default function GitActionsControl({
         terminology: changeRequestTerminology,
       })
     : null;
+  // Follows the live status so the button tracks the tree while the dialog is open. Until the
+  // status loads, keep the option enabled: the server stays the authority and rejects a stale
+  // request with its own error.
+  const featureBranchUnavailableReason = pendingDefaultBranchAction
+    ? resolveFeatureBranchUnavailableReason({
+        branchName: pendingDefaultBranchAction.branchName,
+        hasWorkingTreeChanges: gitStatus?.hasWorkingTreeChanges ?? true,
+      })
+    : null;
 
   useEffect(() => {
     if (gitCwd === null) {
@@ -2117,6 +2127,9 @@ export default function GitActionsControl({
               {pendingDefaultBranchActionCopy?.title ?? "Run action on default branch?"}
             </DialogTitle>
             <DialogDescription>{pendingDefaultBranchActionCopy?.description}</DialogDescription>
+            {featureBranchUnavailableReason && (
+              <p className="text-xs text-muted-foreground">{featureBranchUnavailableReason}</p>
+            )}
           </DialogHeader>
           <DialogFooter variant="bare" className="sm:flex-wrap sm:items-center">
             <Button
@@ -2140,7 +2153,7 @@ export default function GitActionsControl({
               className="w-full max-w-full sm:w-auto"
               size="sm-multiline"
               onClick={checkoutFeatureBranchAndContinuePendingAction}
-              disabled={!canChangeThreadBranch}
+              disabled={!canChangeThreadBranch || featureBranchUnavailableReason !== null}
             >
               Check out feature branch & continue
             </Button>