fix(paths): handle submodule gitdirs in worktree IDs

cmd/entire/cli/paths/worktree.go

@@ -36,23 +36,36 @@ func GetWorktreeID(worktreePath string) (string, error) {
 	}
 
 	gitdir := strings.TrimPrefix(line, "gitdir: ")
+	if worktreeID, found := parseWorktreeID(gitdir); found {
+		return worktreeID, nil
+	}
+
+	return "", fmt.Errorf("unexpected gitdir format (no worktrees): %s", gitdir)
+}
+
+func parseWorktreeID(gitdir string) (string, bool) {
+	gitdir = strings.TrimSuffix(strings.ReplaceAll(gitdir, "\\", "/"), "/")
+
+	// Submodule gitdirs live under .git/modules/<path>. If that submodule
+	// repository has its own linked worktree, the gitdir ends with
+	// .git/modules/<path>/worktrees/<id>. A /worktrees/ segment before the
+	// final /modules/ belongs to the superproject's worktree, not the submodule.
+	if modulesIndex := strings.LastIndex(gitdir, "/modules/"); modulesIndex >= 0 {
+		afterModules := gitdir[modulesIndex+len("/modules/"):]
+		if _, worktreeID, found := strings.Cut(afterModules, "/worktrees/"); found {
+			return strings.TrimSuffix(worktreeID, "/"), true
+		}
+		return "", true
+	}
 
 	// Extract worktree name from path like /repo/.git/worktrees/<name>
 	// or /repo/.bare/worktrees/<name> (bare repo + worktree layout).
 	// The path after the marker is the worktree identifier.
-	var worktreeID string
-	var found bool
 	for _, marker := range []string{".git/worktrees/", ".bare/worktrees/"} {
-		_, worktreeID, found = strings.Cut(gitdir, marker)
-		if found {
-			break
+		if _, worktreeID, found := strings.Cut(gitdir, marker); found {
+			return strings.TrimSuffix(worktreeID, "/"), true
 		}
 	}
-	if !found {
-		return "", fmt.Errorf("unexpected gitdir format (no worktrees): %s", gitdir)
-	}
-	// Remove trailing slashes if any
-	worktreeID = strings.TrimSuffix(worktreeID, "/")
 
-	return worktreeID, nil
+	return "", false
 }

cmd/entire/cli/paths/worktree_test.go

@@ -8,6 +8,8 @@ import (
 )
 
 func TestGetWorktreeID(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		name       string
 		setupFunc  func(dir string) error
@@ -22,6 +24,46 @@ func TestGetWorktreeID(t *testing.T) {
 			},
 			wantID: "",
 		},
+		{
+			name: "ordinary submodule relative gitdir",
+			setupFunc: func(dir string) error {
+				content := "gitdir: ../../.git/modules/deps/go-git\n"
+				return os.WriteFile(filepath.Join(dir, ".git"), []byte(content), 0o644)
+			},
+			wantID: "",
+		},
+		{
+			name: "ordinary submodule absolute gitdir",
+			setupFunc: func(dir string) error {
+				content := "gitdir: /repo/.git/modules/deps/go-git\n"
+				return os.WriteFile(filepath.Join(dir, ".git"), []byte(content), 0o644)
+			},
+			wantID: "",
+		},
+		{
+			name: "nested ordinary submodule gitdir",
+			setupFunc: func(dir string) error {
+				content := "gitdir: /repo/.git/modules/libs/go-git/modules/vendor/crypto\n"
+				return os.WriteFile(filepath.Join(dir, ".git"), []byte(content), 0o644)
+			},
+			wantID: "",
+		},
+		{
+			name: "linked worktree of submodule",
+			setupFunc: func(dir string) error {
+				content := "gitdir: /repo/.git/modules/deps/go-git/worktrees/sub-linked\n"
+				return os.WriteFile(filepath.Join(dir, ".git"), []byte(content), 0o644)
+			},
+			wantID: "sub-linked",
+		},
+		{
+			name: "ordinary submodule inside linked superproject worktree",
+			setupFunc: func(dir string) error {
+				content := "gitdir: /repo/.git/worktrees/super-linked/modules/deps/go-git\n"
+				return os.WriteFile(filepath.Join(dir, ".git"), []byte(content), 0o644)
+			},
+			wantID: "",
+		},
 		{
 			name: "linked worktree simple name",
 			setupFunc: func(dir string) error {
@@ -83,6 +125,8 @@ func TestGetWorktreeID(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
 			dir := t.TempDir()
 			if err := tt.setupFunc(dir); err != nil {
 				t.Fatalf("setup failed: %v", err)