fix(git): find .beads from nested worktrees (GH#509)

When worktrees are nested under the main repo (e.g.,
/project/.worktrees/feature/), bd now correctly finds .beads/ in the
parent repo.

The fix simplifies GetMainRepoRoot() to use `git rev-parse --git-common-dir`
which always returns the main repo's .git directory, regardless of whether
we're in a regular repo, a worktree, or a nested worktree.

- Simplified GetMainRepoRoot() implementation
- Added tests for nested worktree scenarios
- Updated CHANGELOG.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -30,6 +30,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - Worktree lifecycle management with sparse checkout for sync branches
   - Automatic detection and user-friendly warnings for worktree conflicts
 
+### Fixed
+
+- **`bd` now finds `.beads` from nested worktrees** (GH#509)
+  - When worktrees are nested under the main repo (e.g., `/project/.worktrees/feature/`),
+    `bd` now correctly finds `.beads/` in the parent repo
+  - Uses `git rev-parse --git-common-dir` to reliably locate the main repository root
+  - Works from any subdirectory within the nested worktree
+
 ## [0.29.0] - 2025-12-03
 
 ### Added

internal/git/gitdir.go

@@ -77,48 +77,30 @@ func IsWorktree() bool {
 // GetMainRepoRoot returns the main repository root directory.
 // When in a worktree, this returns the main repository root.
 // Otherwise, it returns the regular repository root.
+//
+// For nested worktrees (worktrees located under the main repo, e.g.,
+// /project/.worktrees/feature/), this correctly returns the main repo
+// root (/project/) by using git rev-parse --git-common-dir which always
+// points to the main repo's .git directory. (GH#509)
 func GetMainRepoRoot() (string, error) {
-	if IsWorktree() {
+	// Use --git-common-dir which always returns the main repo's .git directory,
-		// In worktree: read .git file to find main repo
+	// even when running from within a worktree or its subdirectories.
-		gitFileContent := getGitDirNoError("--git-dir")
+	// This is the most reliable method for finding the main repo root.
-		if gitFileContent == "" {
+	commonDir := getGitDirNoError("--git-common-dir")
-			return "", fmt.Errorf("not a git repository")
+	if commonDir == "" {
-		}
+		return "", fmt.Errorf("not a git repository")
-
-		// If gitFileContent contains "worktrees", it's a worktree path
-		// Read the .git file to get the main git dir
-		if strings.Contains(gitFileContent, "worktrees") {
-			content, err := exec.Command("cat", ".git").Output()
-			if err == nil {
-				line := strings.TrimSpace(string(content))
-				if strings.HasPrefix(line, "gitdir: ") {
-					gitDir := strings.TrimPrefix(line, "gitdir: ")
-					// Remove /worktrees/* part
-					if idx := strings.Index(gitDir, "/worktrees/"); idx > 0 {
-						gitDir = gitDir[:idx]
-					}
-					return filepath.Dir(gitDir), nil
-				}
-			}
-		}
-
-		// Fallback: use --git-common-dir with validation
-		commonDir := getGitDirNoError("--git-common-dir")
-		if commonDir != "" {
-			// Validate that commonDir exists
-			if _, err := exec.Command("test", "-d", commonDir).Output(); err == nil {
-				return filepath.Dir(commonDir), nil
-			}
-		}
-
-		return "", fmt.Errorf("unable to determine main repository root")
-	} else {
-		gitDir, err := GetGitDir()
-		if err != nil {
-			return "", err
-		}
-		return filepath.Dir(gitDir), nil
 	}
+
+	// Convert to absolute path to handle relative paths correctly
+	absCommonDir, err := filepath.Abs(commonDir)
+	if err != nil {
+		return "", fmt.Errorf("failed to resolve common dir path: %w", err)
+	}
+
+	// The main repo root is the parent of the .git directory
+	mainRepoRoot := filepath.Dir(absCommonDir)
+
+	return mainRepoRoot, nil
 }
 
 // getGitDirNoError is a helper that returns empty string on error

internal/git/worktree_test.go

@@ -860,3 +860,199 @@ func TestCountJSONLIssues(t *testing.T) {
 		})
 	}
 }
+
+// TestGetMainRepoRoot tests the GetMainRepoRoot function for various scenarios
+func TestGetMainRepoRoot(t *testing.T) {
+	t.Run("returns correct root for regular repo", func(t *testing.T) {
+		repoPath, cleanup := setupTestRepo(t)
+		defer cleanup()
+
+		// Save current dir and change to repo
+		originalDir, err := os.Getwd()
+		if err != nil {
+			t.Fatalf("Failed to get current dir: %v", err)
+		}
+		defer func() { _ = os.Chdir(originalDir) }()
+
+		if err := os.Chdir(repoPath); err != nil {
+			t.Fatalf("Failed to chdir to repo: %v", err)
+		}
+
+		root, err := GetMainRepoRoot()
+		if err != nil {
+			t.Fatalf("GetMainRepoRoot failed: %v", err)
+		}
+
+		// Resolve symlinks for comparison (e.g., /tmp -> /private/tmp on macOS)
+		expectedRoot, _ := filepath.EvalSymlinks(repoPath)
+		actualRoot, _ := filepath.EvalSymlinks(root)
+
+		if actualRoot != expectedRoot {
+			t.Errorf("GetMainRepoRoot() = %s, want %s", actualRoot, expectedRoot)
+		}
+	})
+
+	t.Run("returns main repo root from worktree", func(t *testing.T) {
+		repoPath, cleanup := setupTestRepo(t)
+		defer cleanup()
+
+		wm := NewWorktreeManager(repoPath)
+		worktreePath := filepath.Join(t.TempDir(), "test-worktree")
+
+		if err := wm.CreateBeadsWorktree("test-branch", worktreePath); err != nil {
+			t.Fatalf("CreateBeadsWorktree failed: %v", err)
+		}
+
+		// Save current dir and change to worktree
+		originalDir, err := os.Getwd()
+		if err != nil {
+			t.Fatalf("Failed to get current dir: %v", err)
+		}
+		defer func() { _ = os.Chdir(originalDir) }()
+
+		if err := os.Chdir(worktreePath); err != nil {
+			t.Fatalf("Failed to chdir to worktree: %v", err)
+		}
+
+		root, err := GetMainRepoRoot()
+		if err != nil {
+			t.Fatalf("GetMainRepoRoot failed: %v", err)
+		}
+
+		// Resolve symlinks for comparison
+		expectedRoot, _ := filepath.EvalSymlinks(repoPath)
+		actualRoot, _ := filepath.EvalSymlinks(root)
+
+		if actualRoot != expectedRoot {
+			t.Errorf("GetMainRepoRoot() = %s, want %s (main repo)", actualRoot, expectedRoot)
+		}
+	})
+
+	t.Run("returns main repo root from nested worktree (GH#509)", func(t *testing.T) {
+		repoPath, cleanup := setupTestRepo(t)
+		defer cleanup()
+
+		// Create a nested worktree directory structure: repo/.worktrees/feature/
+		nestedWorktreePath := filepath.Join(repoPath, ".worktrees", "feature-branch")
+
+		wm := NewWorktreeManager(repoPath)
+		if err := wm.CreateBeadsWorktree("feature-branch", nestedWorktreePath); err != nil {
+			t.Fatalf("CreateBeadsWorktree failed: %v", err)
+		}
+
+		// Save current dir and change to nested worktree
+		originalDir, err := os.Getwd()
+		if err != nil {
+			t.Fatalf("Failed to get current dir: %v", err)
+		}
+		defer func() { _ = os.Chdir(originalDir) }()
+
+		if err := os.Chdir(nestedWorktreePath); err != nil {
+			t.Fatalf("Failed to chdir to nested worktree: %v", err)
+		}
+
+		root, err := GetMainRepoRoot()
+		if err != nil {
+			t.Fatalf("GetMainRepoRoot failed: %v", err)
+		}
+
+		// Resolve symlinks for comparison
+		expectedRoot, _ := filepath.EvalSymlinks(repoPath)
+		actualRoot, _ := filepath.EvalSymlinks(root)
+
+		if actualRoot != expectedRoot {
+			t.Errorf("GetMainRepoRoot() = %s, want %s (main repo, not worktree)", actualRoot, expectedRoot)
+		}
+	})
+
+	t.Run("returns main repo root from subdirectory of nested worktree", func(t *testing.T) {
+		repoPath, cleanup := setupTestRepo(t)
+		defer cleanup()
+
+		// Create a nested worktree
+		nestedWorktreePath := filepath.Join(repoPath, ".worktrees", "feature-branch")
+
+		wm := NewWorktreeManager(repoPath)
+		if err := wm.CreateBeadsWorktree("feature-branch", nestedWorktreePath); err != nil {
+			t.Fatalf("CreateBeadsWorktree failed: %v", err)
+		}
+
+		// Create a subdirectory in the worktree
+		subDir := filepath.Join(nestedWorktreePath, "some", "nested", "dir")
+		if err := os.MkdirAll(subDir, 0750); err != nil {
+			t.Fatalf("Failed to create subdir: %v", err)
+		}
+
+		// Save current dir and change to subdirectory
+		originalDir, err := os.Getwd()
+		if err != nil {
+			t.Fatalf("Failed to get current dir: %v", err)
+		}
+		defer func() { _ = os.Chdir(originalDir) }()
+
+		if err := os.Chdir(subDir); err != nil {
+			t.Fatalf("Failed to chdir to subdir: %v", err)
+		}
+
+		root, err := GetMainRepoRoot()
+		if err != nil {
+			t.Fatalf("GetMainRepoRoot failed: %v", err)
+		}
+
+		// Resolve symlinks for comparison
+		expectedRoot, _ := filepath.EvalSymlinks(repoPath)
+		actualRoot, _ := filepath.EvalSymlinks(root)
+
+		if actualRoot != expectedRoot {
+			t.Errorf("GetMainRepoRoot() = %s, want %s (main repo)", actualRoot, expectedRoot)
+		}
+	})
+}
+
+// TestIsWorktree tests the IsWorktree function
+func TestIsWorktree(t *testing.T) {
+	t.Run("returns false for regular repo", func(t *testing.T) {
+		repoPath, cleanup := setupTestRepo(t)
+		defer cleanup()
+
+		originalDir, err := os.Getwd()
+		if err != nil {
+			t.Fatalf("Failed to get current dir: %v", err)
+		}
+		defer func() { _ = os.Chdir(originalDir) }()
+
+		if err := os.Chdir(repoPath); err != nil {
+			t.Fatalf("Failed to chdir to repo: %v", err)
+		}
+
+		if IsWorktree() {
+			t.Error("IsWorktree() should return false for regular repo")
+		}
+	})
+
+	t.Run("returns true for worktree", func(t *testing.T) {
+		repoPath, cleanup := setupTestRepo(t)
+		defer cleanup()
+
+		wm := NewWorktreeManager(repoPath)
+		worktreePath := filepath.Join(t.TempDir(), "test-worktree")
+
+		if err := wm.CreateBeadsWorktree("test-branch", worktreePath); err != nil {
+			t.Fatalf("CreateBeadsWorktree failed: %v", err)
+		}
+
+		originalDir, err := os.Getwd()
+		if err != nil {
+			t.Fatalf("Failed to get current dir: %v", err)
+		}
+		defer func() { _ = os.Chdir(originalDir) }()
+
+		if err := os.Chdir(worktreePath); err != nil {
+			t.Fatalf("Failed to chdir to worktree: %v", err)
+		}
+
+		if !IsWorktree() {
+			t.Error("IsWorktree() should return true for worktree")
+		}
+	})
+}