fix(gateway): log startup errors before exit (#2414)

* fix(gateway): log startup errors before exit

* preserve deferred startup failure logging

pkg/gateway/gateway.go

@@ -111,7 +111,7 @@ func (p *startupBlockedProvider) GetDefaultModel() string {
 }
 
 // Run starts the gateway runtime using the configuration loaded from configPath.
-func Run(debug bool, homePath, configPath string, allowEmptyStartup bool) error {
+func Run(debug bool, homePath, configPath string, allowEmptyStartup bool) (runErr error) {
 	panicPath := filepath.Join(homePath, logPath, panicFile)
 	panicFunc, err := logger.InitPanic(panicPath)
 	if err != nil {
@@ -129,14 +129,25 @@ func Run(debug bool, homePath, configPath string, allowEmptyStartup bool) error
 	} else {
 		logger.SetLevelFromString(config.ResolveGatewayLogLevel(configPath))
 	}
+	defer func() {
+		if runErr != nil {
+			logger.ErrorCF("gateway", "Gateway startup failed", map[string]any{
+				"config_path": configPath,
+				"error":       runErr.Error(),
+				"home_path":   homePath,
+				"allow_empty": allowEmptyStartup,
+				"debug":       debug,
+			})
+		}
+	}()
 
 	cfg, err := config.LoadConfig(configPath)
 	if err != nil {
-		logger.Fatalf("error loading config: %v", err)
+		return fmt.Errorf("error loading config: %w", err)
 	}
 
 	if err = preCheckConfig(cfg); err != nil {
-		logger.Fatalf("config pre-check failed: %v", err)
+		return fmt.Errorf("config pre-check failed: %w", err)
 	}
 
 	// Debug mode permanently overrides the config log level to DEBUG.

pkg/gateway/gateway_test.go

@@ -0,0 +1,108 @@
+package gateway
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/sipeed/picoclaw/pkg/config"
+)
+
+func TestRun_StartupFailuresReturnErrorAndEmitStructuredLog(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name       string
+		prepare    func(t *testing.T, dir string) string
+		wantErr    string
+		wantLogSub string
+	}{
+		{
+			name: "invalid config returns load error",
+			prepare: func(t *testing.T, dir string) string {
+				t.Helper()
+				cfgPath := filepath.Join(dir, "invalid-config.json")
+				if err := os.WriteFile(cfgPath, []byte("{invalid-json"), 0o644); err != nil {
+					t.Fatalf("WriteFile(invalid config) error = %v", err)
+				}
+				return cfgPath
+			},
+			wantErr:    "error loading config:",
+			wantLogSub: "error loading config:",
+		},
+		{
+			name: "invalid config returns pre-check error",
+			prepare: func(t *testing.T, dir string) string {
+				t.Helper()
+				cfg := config.DefaultConfig()
+				cfg.Gateway.Port = 0
+				cfgPath := filepath.Join(dir, "config.json")
+				if err := config.SaveConfig(cfgPath, cfg); err != nil {
+					t.Fatalf("SaveConfig() error = %v", err)
+				}
+				return cfgPath
+			},
+			wantErr:    "config pre-check failed: invalid gateway port: 0",
+			wantLogSub: "config pre-check failed: invalid gateway port: 0",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			homeDir := t.TempDir()
+			configPath := tt.prepare(t, homeDir)
+
+			cmd := exec.Command(os.Args[0], "-test.run=TestGatewayRunStartupFailureHelper")
+			cmd.Env = append(os.Environ(),
+				"GO_WANT_GATEWAY_RUN_HELPER=1",
+				"PICO_TEST_HOME="+homeDir,
+				"PICO_TEST_CONFIG="+configPath,
+			)
+
+			output, err := cmd.CombinedOutput()
+			if err != nil {
+				t.Fatalf("helper exited unexpectedly: %v\noutput:\n%s", err, string(output))
+			}
+
+			out := string(output)
+			if !strings.Contains(out, tt.wantErr) {
+				t.Fatalf("helper output missing expected error substring %q:\n%s", tt.wantErr, out)
+			}
+
+			logData, readErr := os.ReadFile(filepath.Join(homeDir, logPath, logFile))
+			if readErr != nil {
+				t.Fatalf("ReadFile(gateway.log) error = %v", readErr)
+			}
+			logText := string(logData)
+			if !strings.Contains(logText, "Gateway startup failed") {
+				t.Fatalf("gateway.log missing structured startup failure log:\n%s", logText)
+			}
+			if !strings.Contains(logText, tt.wantLogSub) {
+				t.Fatalf("gateway.log missing expected failure detail %q:\n%s", tt.wantLogSub, logText)
+			}
+		})
+	}
+}
+
+func TestGatewayRunStartupFailureHelper(t *testing.T) {
+	if os.Getenv("GO_WANT_GATEWAY_RUN_HELPER") != "1" {
+		return
+	}
+
+	homeDir := os.Getenv("PICO_TEST_HOME")
+	configPath := os.Getenv("PICO_TEST_CONFIG")
+
+	err := Run(false, homeDir, configPath, false)
+	if err == nil {
+		fmt.Fprintln(os.Stdout, "expected startup error, got nil")
+		os.Exit(2)
+	}
+
+	fmt.Fprintln(os.Stdout, err.Error())
+	os.Exit(0)
+}