Show parent project name in worktree status line

internal/statusline/statusline.go

@@ -169,6 +169,11 @@ func (sl *StatusLine) renderDir() string {
 	}
 
 	displayName := filepath.Base(displayBase)
+	if inWorktree {
+		if mainRepo := getMainRepoName(displayBase); mainRepo != "" {
+			displayName = mainRepo + "/" + displayName
+		}
+	}
 	icon := sl.config.Icon
 	if icon != "" {
 		icon += " "
@@ -275,6 +280,52 @@ func (sl *StatusLine) findWorktreeRootCached(dir string) (string, bool) {
 	return root, isWorktree
 }
 
+// parseMainRepoName reads the .git file in a worktree root to determine the
+// main repository name. In a git worktree, .git is a file containing:
+//
+//	gitdir: /path/to/main/repo/.git/worktrees/worktree-name
+//
+// Returns "" on any failure (not a worktree, can't read, can't parse).
+func parseMainRepoName(worktreeRoot string) string {
+	data, err := os.ReadFile(filepath.Join(worktreeRoot, ".git"))
+	if err != nil {
+		return ""
+	}
+
+	content := strings.TrimSpace(string(data))
+	if !strings.HasPrefix(content, "gitdir: ") {
+		return ""
+	}
+
+	gitdir := strings.TrimPrefix(content, "gitdir: ")
+	if !filepath.IsAbs(gitdir) {
+		gitdir = filepath.Clean(filepath.Join(worktreeRoot, gitdir))
+	}
+
+	// Find the ".git" segment in the path to locate the main repo root.
+	// e.g. /path/to/main-repo/.git/worktrees/name → /path/to/main-repo
+	sep := string(filepath.Separator)
+	marker := sep + ".git" + sep
+	idx := strings.LastIndex(gitdir, marker)
+	if idx < 0 {
+		return ""
+	}
+
+	return filepath.Base(gitdir[:idx])
+}
+
+// getMainRepoName returns the main repository name for a worktree, with caching.
+func getMainRepoName(worktreeRoot string) string {
+	cacheKey := "main-repo:" + worktreeRoot
+	if cached, ok := statusCache.Get(cacheKey); ok {
+		return cached
+	}
+
+	name := parseMainRepoName(worktreeRoot)
+	statusCache.Set(cacheKey, name, cache.WorktreeTTL)
+	return name
+}
+
 func (sl *StatusLine) renderModel() string {
 	return colors.Wrap(colors.Magenta, sl.input.Model.DisplayName)
 }

internal/statusline/statusline_test.go

@@ -585,6 +585,14 @@ func TestRenderDir_WorktreeIndicator(t *testing.T) {
 	if !strings.Contains(result, "⎇") {
 		t.Errorf("renderDir should include ⎇ indicator for worktree, got: %s", result)
 	}
+
+	// Should show mainRepoName/worktreeName
+	mainRepoName := filepath.Base(tmpDir)
+	worktreeName := filepath.Base(worktreeDir)
+	expected := mainRepoName + "/" + worktreeName
+	if !strings.Contains(result, expected) {
+		t.Errorf("renderDir should show '%s', got: %s", expected, result)
+	}
 }
 
 // TestRenderDir_NoIndicatorForMainRepo does not show ⎇ for main repo
@@ -718,10 +726,11 @@ func TestRenderDir_CurrentDirInWorktree(t *testing.T) {
 	if !strings.Contains(result, worktreeName) {
 		t.Errorf("should show worktree name '%s', got: %s", worktreeName, result)
 	}
-	// Should NOT show the main repo name
+	// Should show the main repo name as prefix
 	mainRepoName := filepath.Base(tmpDir)
-	if strings.Contains(result, mainRepoName) {
-		t.Errorf("should NOT show main repo name '%s' when in worktree, got: %s", mainRepoName, result)
+	expected := mainRepoName + "/" + worktreeName
+	if !strings.Contains(result, expected) {
+		t.Errorf("should show '%s' (mainRepo/worktree), got: %s", expected, result)
 	}
 }
 
@@ -759,13 +768,15 @@ func TestRenderDir_CurrentDirInWorktreeSubdir(t *testing.T) {
 
 	result := sl.renderDir()
 
-	// Should show worktree name + /src with ⎇ indicator
+	// Should show mainRepo/worktreeName + /src with ⎇ indicator
 	worktreeName := filepath.Base(worktreeDir)
+	mainRepoName := filepath.Base(tmpDir)
 	if !strings.Contains(result, "⎇") {
 		t.Errorf("should show ⎇ indicator, got: %s", result)
 	}
-	if !strings.Contains(result, worktreeName) {
-		t.Errorf("should show worktree name '%s', got: %s", worktreeName, result)
+	expected := mainRepoName + "/" + worktreeName
+	if !strings.Contains(result, expected) {
+		t.Errorf("should show '%s', got: %s", expected, result)
 	}
 	if !strings.Contains(result, "/src") {
 		t.Errorf("should show subdir '/src', got: %s", result)
@@ -1243,6 +1254,68 @@ func TestRenderCost_ShowBurnRateDisabled(t *testing.T) {
 	}
 }
 
+// TestGetMainRepoName_ValidWorktree returns correct main repo name
+func TestGetMainRepoName_ValidWorktree(t *testing.T) {
+	tmpDir := setupTestGitRepo(t)
+	defer os.RemoveAll(tmpDir)
+
+	// Create a worktree
+	worktreeDir := filepath.Join(os.TempDir(), "prism-test-mainrepo-valid")
+	defer os.RemoveAll(worktreeDir)
+
+	cmd := exec.Command("git", "worktree", "add", worktreeDir, "HEAD")
+	cmd.Dir = tmpDir
+	if err := cmd.Run(); err != nil {
+		t.Fatalf("failed to create worktree: %v", err)
+	}
+
+	name := getMainRepoName(worktreeDir)
+	expected := filepath.Base(tmpDir)
+	if name != expected {
+		t.Errorf("getMainRepoName should return '%s', got '%s'", expected, name)
+	}
+}
+
+// TestGetMainRepoName_MainRepo returns empty for a regular (non-worktree) repo
+func TestGetMainRepoName_MainRepo(t *testing.T) {
+	tmpDir := setupTestGitRepo(t)
+	defer os.RemoveAll(tmpDir)
+
+	name := getMainRepoName(tmpDir)
+	if name != "" {
+		t.Errorf("getMainRepoName should return '' for main repo, got '%s'", name)
+	}
+}
+
+// TestParseMainRepoName_Fallbacks verifies graceful failures
+func TestParseMainRepoName_Fallbacks(t *testing.T) {
+	// Nonexistent directory
+	if name := parseMainRepoName("/nonexistent/path"); name != "" {
+		t.Errorf("expected '' for nonexistent dir, got '%s'", name)
+	}
+
+	// Directory without .git
+	tmpDir, err := os.MkdirTemp("", "prism-test-nogit-*")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	if name := parseMainRepoName(tmpDir); name != "" {
+		t.Errorf("expected '' for dir without .git, got '%s'", name)
+	}
+
+	// .git as directory (regular repo, not worktree)
+	gitDir := filepath.Join(tmpDir, ".git")
+	if err := os.MkdirAll(gitDir, 0755); err != nil {
+		t.Fatal(err)
+	}
+
+	if name := parseMainRepoName(tmpDir); name != "" {
+		t.Errorf("expected '' for .git directory, got '%s'", name)
+	}
+}
+
 // TestRenderCost_NoCacheIndicatorWhenZero verifies no cache indicator when no cache reads
 func TestRenderCost_NoCacheIndicatorWhenZero(t *testing.T) {
 	sl := &StatusLine{