feat: walk up directory tree to find .cheat directory (#602)

Previously cheat only checked the current working directory for a .cheat
subdirectory. Now it walks upward through ancestor directories, stopping
at the first .cheat directory found. This mirrors how git discovers .git
directories, so users can place .cheat at their project root and have it
work from any subdirectory.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/config/config_extended_test.go

@@ -86,6 +86,187 @@ func TestConfigLocalCheatpath(t *testing.T) {
 	}
 }
 
+// TestConfigLocalCheatpathInParent tests that .cheat in a parent directory is found
+func TestConfigLocalCheatpathInParent(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "cheat-config-test-*")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	// Resolve symlinks in temp dir path (macOS /var -> /private/var)
+	tempDir, err = filepath.EvalSymlinks(tempDir)
+	if err != nil {
+		t.Fatalf("failed to resolve temp dir symlinks: %v", err)
+	}
+
+	oldCwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("failed to get cwd: %v", err)
+	}
+	defer os.Chdir(oldCwd)
+
+	// Create .cheat in the root of the temp dir
+	localCheat := filepath.Join(tempDir, ".cheat")
+	if err := os.Mkdir(localCheat, 0755); err != nil {
+		t.Fatalf("failed to create .cheat dir: %v", err)
+	}
+
+	// Create a subdirectory and cd into it
+	subDir := filepath.Join(tempDir, "sub")
+	if err := os.Mkdir(subDir, 0755); err != nil {
+		t.Fatalf("failed to create sub dir: %v", err)
+	}
+	if err := os.Chdir(subDir); err != nil {
+		t.Fatalf("failed to chdir: %v", err)
+	}
+
+	conf, err := New(map[string]interface{}{}, mock.Path("conf/empty.yml"), false)
+	if err != nil {
+		t.Errorf("failed to load config: %v", err)
+	}
+
+	found := false
+	for _, cp := range conf.Cheatpaths {
+		if cp.Name == "cwd" && cp.Path == localCheat {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Error("parent .cheat directory was not added to cheatpaths")
+	}
+}
+
+// TestConfigLocalCheatpathNearestWins tests that the nearest .cheat wins
+func TestConfigLocalCheatpathNearestWins(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "cheat-config-test-*")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	// Resolve symlinks in temp dir path (macOS /var -> /private/var)
+	tempDir, err = filepath.EvalSymlinks(tempDir)
+	if err != nil {
+		t.Fatalf("failed to resolve temp dir symlinks: %v", err)
+	}
+
+	oldCwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("failed to get cwd: %v", err)
+	}
+	defer os.Chdir(oldCwd)
+
+	// Create .cheat at root
+	if err := os.Mkdir(filepath.Join(tempDir, ".cheat"), 0755); err != nil {
+		t.Fatalf("failed to create root .cheat dir: %v", err)
+	}
+
+	// Create sub/.cheat (the nearer one)
+	subDir := filepath.Join(tempDir, "sub")
+	if err := os.Mkdir(subDir, 0755); err != nil {
+		t.Fatalf("failed to create sub dir: %v", err)
+	}
+	nearCheat := filepath.Join(subDir, ".cheat")
+	if err := os.Mkdir(nearCheat, 0755); err != nil {
+		t.Fatalf("failed to create near .cheat dir: %v", err)
+	}
+
+	// cd into sub/deep/
+	deepDir := filepath.Join(subDir, "deep")
+	if err := os.Mkdir(deepDir, 0755); err != nil {
+		t.Fatalf("failed to create deep dir: %v", err)
+	}
+	if err := os.Chdir(deepDir); err != nil {
+		t.Fatalf("failed to chdir: %v", err)
+	}
+
+	conf, err := New(map[string]interface{}{}, mock.Path("conf/empty.yml"), false)
+	if err != nil {
+		t.Errorf("failed to load config: %v", err)
+	}
+
+	found := false
+	for _, cp := range conf.Cheatpaths {
+		if cp.Name == "cwd" {
+			if cp.Path != nearCheat {
+				t.Errorf("expected nearest .cheat %s, got %s", nearCheat, cp.Path)
+			}
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Error("no cwd cheatpath found")
+	}
+}
+
+// TestConfigNoLocalCheatpath tests that no cwd cheatpath is added when no .cheat exists
+func TestConfigNoLocalCheatpath(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "cheat-config-test-*")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	oldCwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("failed to get cwd: %v", err)
+	}
+	defer os.Chdir(oldCwd)
+
+	if err := os.Chdir(tempDir); err != nil {
+		t.Fatalf("failed to chdir: %v", err)
+	}
+
+	conf, err := New(map[string]interface{}{}, mock.Path("conf/empty.yml"), false)
+	if err != nil {
+		t.Errorf("failed to load config: %v", err)
+	}
+
+	for _, cp := range conf.Cheatpaths {
+		if cp.Name == "cwd" {
+			t.Error("cwd cheatpath should not be added when no .cheat exists")
+		}
+	}
+}
+
+// TestConfigLocalCheatpathFileSkipped tests that a .cheat file (not dir) is skipped
+func TestConfigLocalCheatpathFileSkipped(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "cheat-config-test-*")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	oldCwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("failed to get cwd: %v", err)
+	}
+	defer os.Chdir(oldCwd)
+
+	// Create .cheat as a file, not a directory
+	if err := os.WriteFile(filepath.Join(tempDir, ".cheat"), []byte("not a dir"), 0644); err != nil {
+		t.Fatalf("failed to create .cheat file: %v", err)
+	}
+
+	if err := os.Chdir(tempDir); err != nil {
+		t.Fatalf("failed to chdir: %v", err)
+	}
+
+	conf, err := New(map[string]interface{}{}, mock.Path("conf/empty.yml"), false)
+	if err != nil {
+		t.Errorf("failed to load config: %v", err)
+	}
+
+	for _, cp := range conf.Cheatpaths {
+		if cp.Name == "cwd" {
+			t.Error("cwd cheatpath should not be added for a .cheat file")
+		}
+	}
+}
+
 // TestConfigDefaults tests default values
 func TestConfigDefaults(t *testing.T) {
 	// Load empty config