fix: resolve gateway binary path, pass --config flag, and clarify empty model error (#1337)

pkg/providers/factory.go

@@ -40,6 +40,10 @@ func resolveProviderSelection(cfg *config.Config) (providerSelection, error) {
 	providerName := strings.ToLower(cfg.Agents.Defaults.Provider)
 	lowerModel := strings.ToLower(model)
 
+	if providerName == "" && model == "" {
+		return providerSelection{}, fmt.Errorf("no model configured: agents.defaults.model is empty")
+	}
+
 	sel := providerSelection{
 		providerType: providerTypeHTTPCompat,
 		model:        model,

web/backend/api/gateway.go

@@ -134,6 +134,12 @@ func (h *Handler) startGatewayLocked() (int, error) {
 	execPath := findPicoclawBinary()
 
 	cmd := exec.Command(execPath, "gateway")
+	// Forward the launcher's config path via the environment variable that
+	// GetConfigPath() already reads, so the gateway sub-process uses the same
+	// config file without requiring a --config flag on the gateway subcommand.
+	if h.configPath != "" {
+		cmd.Env = append(os.Environ(), "PICOCLAW_CONFIG="+h.configPath)
+	}
 
 	stdoutPipe, err := cmd.StdoutPipe()
 	if err != nil {
@@ -530,18 +536,32 @@ func (h *Handler) currentGatewayStatus() string {
 }
 
 // findPicoclawBinary locates the picoclaw executable.
-// Tries the same directory as the current executable first, then falls back to $PATH.
+// Search order:
+//  1. PICOCLAW_BINARY environment variable (explicit override)
+//  2. Same directory as the current executable
+//  3. Falls back to "picoclaw" and relies on $PATH
 func findPicoclawBinary() string {
-	if exe, err := os.Executable(); err == nil {
-		dir := filepath.Dir(exe)
-		candidate := filepath.Join(dir, "picoclaw")
-		if runtime.GOOS == "windows" {
-			candidate += ".exe"
+	binaryName := "picoclaw"
+	if runtime.GOOS == "windows" {
+		binaryName = "picoclaw.exe"
+	}
+
+	// 1. Explicit override via environment variable
+	if p := os.Getenv("PICOCLAW_BINARY"); p != "" {
+		if info, _ := os.Stat(p); info != nil && !info.IsDir() {
+			return p
 		}
+	}
+
+	// 2. Same directory as the launcher executable
+	if exe, err := os.Executable(); err == nil {
+		candidate := filepath.Join(filepath.Dir(exe), binaryName)
 		if info, err := os.Stat(candidate); err == nil && !info.IsDir() {
 			return candidate
 		}
 	}
+
+	// 3. Fall back to PATH lookup
 	return "picoclaw"
 }
 

web/backend/api/gateway_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"path/filepath"
 	"strings"
 	"testing"
@@ -120,3 +121,30 @@ func TestGatewayStatusIncludesStartConditionWhenNotReady(t *testing.T) {
 		t.Fatalf("gateway_start_reason missing or not string: %#v", body["gateway_start_reason"])
 	}
 }
+
+func TestFindPicoclawBinary_EnvOverride(t *testing.T) {
+	// Create a temporary file to act as the mock binary
+	tmpDir := t.TempDir()
+	mockBinary := filepath.Join(tmpDir, "picoclaw-mock")
+	if err := os.WriteFile(mockBinary, []byte("mock"), 0o755); err != nil {
+		t.Fatalf("WriteFile() error = %v", err)
+	}
+
+	t.Setenv("PICOCLAW_BINARY", mockBinary)
+
+	got := findPicoclawBinary()
+	if got != mockBinary {
+		t.Errorf("findPicoclawBinary() = %q, want %q", got, mockBinary)
+	}
+}
+
+func TestFindPicoclawBinary_EnvOverride_InvalidPath(t *testing.T) {
+	// When PICOCLAW_BINARY points to a non-existent path, fall through to next strategy
+	t.Setenv("PICOCLAW_BINARY", "/nonexistent/picoclaw-binary")
+
+	got := findPicoclawBinary()
+	// Should not return the invalid path; falls back to "picoclaw" or another found path
+	if got == "/nonexistent/picoclaw-binary" {
+		t.Errorf("findPicoclawBinary() returned invalid env path %q, expected fallback", got)
+	}
+}