fix: auto-configure missing stackparent for branches in stack chain

CLAUDE.md

@@ -95,10 +95,11 @@ git config stack.baseBranch develop  # Default is "main"
 
 ## Testing
 
-Currently no test files exist. When adding tests:
+**Always use `./scripts/test` to run tests** (handles CGO_ENABLED=0 for macOS compatibility).
 
+Test patterns:
 - Use table-driven tests for topological sort and tree building
-- Mock git/gh command execution for unit tests
+- Mock git/gh command execution for unit tests using `testutil.MockGitClient` and `testutil.MockGitHubClient`
 - Consider integration tests that use temporary git repos
 
 **IMPORTANT**: When testing git operations (creating branches, stashing, etc.), always use `./tests/test-repo` directory, NOT the main repository. This keeps the main repo clean and prevents pollution from test branches.

cmd/sync.go

@@ -335,6 +335,48 @@ func runSync(gitClient git.GitClient, githubClient github.GitHubClient) error {
 		}
 	}
 
+	// Detect branches in chain that don't have stackparent configured
+	// and auto-configure them with inferred parents
+	existingBranchNames := make(map[string]bool)
+	for _, b := range stackBranches {
+		existingBranchNames[b.Name] = true
+	}
+
+	// Walk the chain and add missing branches
+	for i, branchName := range chain {
+		if branchName == baseBranch {
+			continue // Skip base branch
+		}
+		if existingBranchNames[branchName] {
+			continue // Already in stackBranches
+		}
+
+		// Infer parent from chain (previous branch in the chain)
+		var inferredParent string
+		if i > 0 {
+			inferredParent = chain[i-1]
+		} else {
+			inferredParent = baseBranch
+		}
+
+		// Check if branch exists locally before adding
+		if gitClient.BranchExists(branchName) {
+			stackBranches = append(stackBranches, stack.StackBranch{
+				Name:   branchName,
+				Parent: inferredParent,
+			})
+			existingBranchNames[branchName] = true
+
+			// Configure stackparent so future syncs work correctly
+			configKey := fmt.Sprintf("branch.%s.stackparent", branchName)
+			if err := gitClient.SetConfig(configKey, inferredParent); err != nil {
+				fmt.Fprintf(os.Stderr, "Warning: failed to set stackparent for %s: %v\n", branchName, err)
+			} else {
+				fmt.Printf("Auto-configured %s with parent %s\n", branchName, inferredParent)
+			}
+		}
+	}
+
 	// Sort branches in topological order (bottom to top)
 	sorted, err := stack.TopologicalSort(stackBranches)
 	if err != nil {
@@ -438,7 +480,7 @@ func runSync(gitClient git.GitClient, githubClient github.GitHubClient) error {
 				grandparent = stack.GetBaseBranch(gitClient)
 			}
 
-			fmt.Printf("  Updating parent from %s to %s\n", branch.Parent, grandparent)
+			fmt.Printf("  ✓ Updated parent from %s to %s\n", branch.Parent, grandparent)
 			configKey := fmt.Sprintf("branch.%s.stackparent", branch.Name)
 			if err := gitClient.SetConfig(configKey, grandparent); err != nil {
 				fmt.Fprintf(os.Stderr, "  Warning: failed to update parent config: %v\n", err)
@@ -668,7 +710,7 @@ func runSync(gitClient git.GitClient, githubClient github.GitHubClient) error {
 							return fmt.Errorf("failed to restore stackparent config: %w", err)
 						}
 
-						fmt.Printf("✓ Rebuilt %s (backup saved as %s)\n", branch.Name, backupBranch)
+						fmt.Printf("  ✓ Rebuilt %s (backup saved as %s)\n", branch.Name, backupBranch)
 						fmt.Printf("  To delete backup later: git branch -D %s\n", backupBranch)
 
 						// Branch is now clean - no need to rebase, just return nil
@@ -788,10 +830,10 @@ func runSync(gitClient git.GitClient, githubClient github.GitHubClient) error {
 				if err := githubClient.UpdatePRBase(pr.Number, branch.Parent); err != nil {
 					fmt.Fprintf(os.Stderr, "  Warning: failed to update PR base: %v\n", err)
 				} else {
-					fmt.Printf("✓   PR #%d updated\n", pr.Number)
+					fmt.Printf("  ✓ PR #%d updated\n", pr.Number)
 				}
 			} else {
-				fmt.Printf("✓   PR #%d base is already correct (%s)\n", pr.Number, pr.Base)
+				fmt.Printf("  ✓ PR #%d base is already correct (%s)\n", pr.Number, pr.Base)
 			}
 		} else {
 			fmt.Printf("  No PR found (create one with 'gh pr create')\n")

cmd/sync_test.go

@@ -664,6 +664,84 @@ func TestRunSyncResume(t *testing.T) {
 	})
 }
 
+func TestRunSyncAutoConfiguresMissingStackparent(t *testing.T) {
+	testutil.SetupTest()
+	defer testutil.TeardownTest()
+
+	t.Run("auto-configures parent branch missing stackparent", func(t *testing.T) {
+		mockGit := new(testutil.MockGitClient)
+		mockGH := new(testutil.MockGitHubClient)
+
+		// Setup: feature-b has stackparent=feature-a, but feature-a has NO stackparent
+		mockGit.On("GetConfig", "stack.sync.stashed").Return("")
+		mockGit.On("GetConfig", "stack.sync.originalBranch").Return("")
+		mockGit.On("GetCurrentBranch").Return("feature-b", nil)
+		mockGit.On("SetConfig", "stack.sync.originalBranch", "feature-b").Return(nil)
+		mockGit.On("IsWorkingTreeClean").Return(true, nil)
+		mockGit.On("GetConfig", "branch.feature-b.stackparent").Return("feature-a")
+		mockGit.On("GetConfig", "stack.baseBranch").Return("").Maybe()
+		mockGit.On("GetDefaultBranch").Return("main").Maybe()
+
+		// Key difference: feature-a is NOT in stackParents (no stackparent configured)
+		stackParents := map[string]string{
+			"feature-b": "feature-a", // feature-a is missing!
+		}
+		mockGit.On("GetAllStackParents").Return(stackParents, nil).Maybe()
+
+		// The fix should auto-configure feature-a with parent=main
+		mockGit.On("BranchExists", "feature-a").Return(true)
+		mockGit.On("SetConfig", "branch.feature-a.stackparent", "main").Return(nil)
+
+		// Parallel operations
+		mockGit.On("Fetch").Return(nil)
+		mockGH.On("GetAllPRs").Return(make(map[string]*github.PRInfo), nil)
+
+		// Worktree checks
+		mockGit.On("GetWorktreeBranches").Return(make(map[string]string), nil)
+		mockGit.On("GetCurrentWorktreePath").Return("/Users/test/repo", nil)
+		mockGit.On("GetRemoteBranchesSet").Return(map[string]bool{
+			"main":      true,
+			"feature-a": true,
+			"feature-b": true,
+		})
+
+		// Process feature-a first (auto-configured)
+		mockGit.On("CheckoutBranch", "feature-a").Return(nil)
+		mockGit.On("GetCommitHash", "feature-a").Return("abc123", nil)
+		mockGit.On("GetCommitHash", "origin/feature-a").Return("abc123", nil)
+		mockGit.On("FetchBranch", "main").Return(nil)
+		mockGit.On("GetUniqueCommitsByPatch", "origin/main", "feature-a").Return([]string{"abc123"}, nil)
+		mockGit.On("GetMergeBase", "feature-a", "origin/main").Return("main123", nil)
+		mockGit.On("GetCommitHash", "origin/main").Return("main123", nil)
+		mockGit.On("Rebase", "origin/main").Return(nil)
+		mockGit.On("FetchBranch", "feature-a").Return(nil)
+		mockGit.On("PushWithExpectedRemote", "feature-a", "abc123").Return(nil)
+
+		// Process feature-b second
+		mockGit.On("CheckoutBranch", "feature-b").Return(nil)
+		mockGit.On("GetCommitHash", "feature-b").Return("def456", nil)
+		mockGit.On("GetCommitHash", "origin/feature-b").Return("def456", nil)
+		mockGit.On("GetUniqueCommitsByPatch", "feature-a", "feature-b").Return([]string{"def456"}, nil)
+		mockGit.On("GetMergeBase", "feature-b", "feature-a").Return("abc123", nil)
+		mockGit.On("GetCommitHash", "feature-a").Return("abc123", nil)
+		mockGit.On("Rebase", "feature-a").Return(nil)
+		mockGit.On("FetchBranch", "feature-b").Return(nil)
+		mockGit.On("PushWithExpectedRemote", "feature-b", "def456").Return(nil)
+
+		// Return to original branch
+		mockGit.On("CheckoutBranch", "feature-b").Return(nil)
+		// Clean up sync state
+		mockGit.On("UnsetConfig", "stack.sync.stashed").Return(nil)
+		mockGit.On("UnsetConfig", "stack.sync.originalBranch").Return(nil)
+
+		err := runSync(mockGit, mockGH)
+
+		assert.NoError(t, err)
+		mockGit.AssertExpectations(t)
+		mockGH.AssertExpectations(t)
+	})
+}
+
 func TestRunSyncAbort(t *testing.T) {
 	testutil.SetupTest()
 	defer testutil.TeardownTest()