feat: 拆分 default workdir 与 session workdir（P0-3）

internal/app/bootstrap_test.go

@@ -49,7 +49,7 @@ func TestNewProgramNormalizesInvalidCurrentModelOnStartup(t *testing.T) {
 	}
 
 	configPath := filepath.Join(configDir, "config.yaml")
-	raw := []byte("selected_provider: openai\ncurrent_model: unsupported-current\nworkdir: .\nshell: powershell\n")
+	raw := []byte("selected_provider: openai\ncurrent_model: unsupported-current\nshell: powershell\n")
 	if err := os.WriteFile(configPath, raw, 0o644); err != nil {
 		t.Fatalf("write config: %v", err)
 	}

internal/config/config_test.go

@@ -41,14 +41,14 @@ func TestParseConfigFormats(t *testing.T) {
 	tests := []struct {
 		name   string
 		data   string
+		err    string
 		assert func(t *testing.T, cfg *Config)
 	}{
 		{
 			name: "current format ignores persisted provider metadata",
 			data: `
 selected_provider: openai
 current_model: gpt-5.4
-workdir: .
 shell: powershell
 
 provider_overrides:
@@ -87,12 +87,31 @@ providers:
 				}
 			},
 		},
+		{
+			name: "legacy default_workdir key is rejected",
+			data: `
+selected_provider: openai
+current_model: gpt-4.1
+default_workdir: ./from-default
+shell: powershell
+`,
+			err: "legacy config key \"default_workdir\" is no longer supported",
+		},
+		{
+			name: "legacy workdir key is rejected",
+			data: `
+selected_provider: openai
+current_model: gpt-4.1
+workdir: ./from-legacy
+shell: powershell
+`,
+			err: "legacy config key \"workdir\" is no longer supported",
+		},
 		{
 			name: "legacy persisted providers list keeps selection only",
 			data: `
 selected_provider: openai
 current_model: gpt-5.4
-workdir: .
 shell: powershell
 providers:
   - name: openai
@@ -167,6 +186,12 @@ providers:
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			cfg, err := parseConfig([]byte(tt.data))
+			if tt.err != "" {
+				if err == nil || !strings.Contains(err.Error(), tt.err) {
+					t.Fatalf("expected parseConfig() error containing %q, got %v", tt.err, err)
+				}
+				return
+			}
 			if err != nil {
 				t.Fatalf("parseConfig() error = %v", err)
 			}
@@ -572,6 +597,9 @@ func TestLoaderLoadAndSaveRoundTrip(t *testing.T) {
 		t.Fatalf("read config file: %v", err)
 	}
 	text := string(data)
+	if strings.Contains(text, "default_workdir:") || strings.Contains(text, "\nworkdir:") || strings.HasPrefix(text, "workdir:") {
+		t.Fatalf("expected persisted config to avoid any workdir keys, got:\n%s", text)
+	}
 	if strings.Contains(text, "\nproviders:") || strings.HasPrefix(text, "providers:") {
 		t.Fatalf("expected persisted config to omit providers, got:\n%s", text)
 	}

internal/config/loader.go

@@ -22,13 +22,14 @@ type Loader struct {
 }
 
 type persistedConfig struct {
-	SelectedProvider string      `yaml:"selected_provider"`
-	CurrentModel     string      `yaml:"current_model"`
-	Workdir          string      `yaml:"workdir"`
-	Shell            string      `yaml:"shell"`
-	MaxLoops         int         `yaml:"max_loops,omitempty"`
-	ToolTimeoutSec   int         `yaml:"tool_timeout_sec,omitempty"`
-	Tools            ToolsConfig `yaml:"tools,omitempty"`
+	SelectedProvider     string      `yaml:"selected_provider"`
+	CurrentModel         string      `yaml:"current_model"`
+	LegacyDefaultWorkdir *string     `yaml:"default_workdir,omitempty"`
+	LegacyWorkdir        *string     `yaml:"workdir,omitempty"`
+	Shell                string      `yaml:"shell"`
+	MaxLoops             int         `yaml:"max_loops,omitempty"`
+	ToolTimeoutSec       int         `yaml:"tool_timeout_sec,omitempty"`
+	Tools                ToolsConfig `yaml:"tools,omitempty"`
 }
 
 func NewLoader(baseDir string, defaults *Config) *Loader {
@@ -152,11 +153,16 @@ func parseCurrentConfig(data []byte) (*Config, error) {
 	if err := yaml.Unmarshal(data, &file); err != nil {
 		return nil, err
 	}
+	if file.LegacyDefaultWorkdir != nil {
+		return nil, fmt.Errorf("legacy config key %q is no longer supported", "default_workdir")
+	}
+	if file.LegacyWorkdir != nil {
+		return nil, fmt.Errorf("legacy config key %q is no longer supported", "workdir")
+	}
 
 	cfg := &Config{
 		SelectedProvider: strings.TrimSpace(file.SelectedProvider),
 		CurrentModel:     strings.TrimSpace(file.CurrentModel),
-		Workdir:          strings.TrimSpace(file.Workdir),
 		Shell:            strings.TrimSpace(file.Shell),
 		MaxLoops:         file.MaxLoops,
 		ToolTimeoutSec:   file.ToolTimeoutSec,
@@ -170,7 +176,6 @@ func marshalPersistedConfig(snapshot Config) ([]byte, error) {
 	file := persistedConfig{
 		SelectedProvider: snapshot.SelectedProvider,
 		CurrentModel:     snapshot.CurrentModel,
-		Workdir:          snapshot.Workdir,
 		Shell:            snapshot.Shell,
 		MaxLoops:         snapshot.MaxLoops,
 		ToolTimeoutSec:   snapshot.ToolTimeoutSec,

internal/config/loader_test.go

@@ -45,6 +45,52 @@ func TestLoaderLoadMalformedYAML(t *testing.T) {
 	}
 }
 
+func TestLoaderRejectsLegacyWorkdirKey(t *testing.T) {
+	t.Parallel()
+
+	loader := NewLoader(t.TempDir(), testDefaultConfig())
+	if err := os.MkdirAll(loader.BaseDir(), 0o755); err != nil {
+		t.Fatalf("mkdir base dir: %v", err)
+	}
+	raw := `
+selected_provider: openai
+current_model: gpt-4.1
+workdir: .
+shell: powershell
+`
+	if err := os.WriteFile(loader.ConfigPath(), []byte(strings.TrimSpace(raw)+"\n"), 0o644); err != nil {
+		t.Fatalf("write legacy config: %v", err)
+	}
+
+	_, err := loader.Load(context.Background())
+	if err == nil || !strings.Contains(err.Error(), "legacy config key \"workdir\" is no longer supported") {
+		t.Fatalf("expected legacy workdir rejection, got %v", err)
+	}
+}
+
+func TestLoaderRejectsLegacyDefaultWorkdirKey(t *testing.T) {
+	t.Parallel()
+
+	loader := NewLoader(t.TempDir(), testDefaultConfig())
+	if err := os.MkdirAll(loader.BaseDir(), 0o755); err != nil {
+		t.Fatalf("mkdir base dir: %v", err)
+	}
+	raw := `
+selected_provider: openai
+current_model: gpt-4.1
+default_workdir: .
+shell: powershell
+`
+	if err := os.WriteFile(loader.ConfigPath(), []byte(strings.TrimSpace(raw)+"\n"), 0o644); err != nil {
+		t.Fatalf("write legacy config: %v", err)
+	}
+
+	_, err := loader.Load(context.Background())
+	if err == nil || !strings.Contains(err.Error(), "legacy config key \"default_workdir\" is no longer supported") {
+		t.Fatalf("expected legacy default_workdir rejection, got %v", err)
+	}
+}
+
 func TestLoaderLoadInvalidBaseDir(t *testing.T) {
 	t.Parallel()
 
@@ -72,7 +118,6 @@ func TestLoaderRewritesLegacyProvidersFormatOnLoad(t *testing.T) {
 	legacy := `
 selected_provider: openai
 current_model: gpt-5.4
-workdir: .
 shell: powershell
 providers:
   - name: openai
@@ -105,6 +150,9 @@ providers:
 		t.Fatalf("read rewritten config: %v", err)
 	}
 	text := string(rewritten)
+	if strings.Contains(text, "default_workdir:") || strings.Contains(text, "\nworkdir:") || strings.HasPrefix(text, "workdir:") {
+		t.Fatalf("expected rewritten config to avoid any workdir keys, got:\n%s", text)
+	}
 	if strings.Contains(text, "provider_overrides:") {
 		t.Fatalf("expected rewritten config to drop provider overrides, got:\n%s", text)
 	}
@@ -126,7 +174,6 @@ func TestLoaderRewritesNormalizedSelectionStateOnLoad(t *testing.T) {
 
 	raw := `
 selected_provider: missing-provider
-workdir: .
 shell: powershell
 `
 	if err := os.WriteFile(loader.ConfigPath(), []byte(strings.TrimSpace(raw)+"\n"), 0o644); err != nil {
@@ -167,7 +214,6 @@ func TestLoaderRewritesMissingCurrentModelOnLoad(t *testing.T) {
 
 	raw := `
 selected_provider: openai
-workdir: .
 shell: powershell
 `
 	if err := os.WriteFile(loader.ConfigPath(), []byte(strings.TrimSpace(raw)+"\n"), 0o644); err != nil {

internal/config/model.go

@@ -30,7 +30,7 @@ type Config struct {
 	Providers        []ProviderConfig `yaml:"-"`
 	SelectedProvider string           `yaml:"selected_provider"`
 	CurrentModel     string           `yaml:"current_model"`
-	Workdir          string           `yaml:"workdir"`
+	Workdir          string           `yaml:"-"`
 	Shell            string           `yaml:"shell"`
 	MaxLoops         int              `yaml:"max_loops,omitempty"`
 	ToolTimeoutSec   int              `yaml:"tool_timeout_sec,omitempty"`