fix deployment and frontend build regressions

cmd/server/main.go

@@ -7,6 +7,9 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"path"
+	"path/filepath"
+	"strings"
 	"time"
 
 	_ "github.com/lib/pq"
@@ -75,7 +78,7 @@ func main() {
 		}
 	}
 
-	mux := newMux(db, fetchModels, fetchSubscriptionPlans)
+	mux := newMux(db, fetchModels, fetchSubscriptionPlans, resolveFrontendDistDir())
 
 	log.Printf("server listening on :%s", addr)
 	if err := http.ListenAndServe(":"+addr, mux); err != nil {
@@ -83,7 +86,7 @@ func main() {
 	}
 }
 
-func newMux(db *sql.DB, fetchModelsFn modelFetcher, fetchPlansFn subscriptionPlanFetcher) *http.ServeMux {
+func newMux(db *sql.DB, fetchModelsFn modelFetcher, fetchPlansFn subscriptionPlanFetcher, frontendDistDir string) *http.ServeMux {
 	mux := http.NewServeMux()
 	mux.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
 		if db == nil {
@@ -122,9 +125,65 @@ func newMux(db *sql.DB, fetchModelsFn modelFetcher, fetchPlansFn subscriptionPla
 		}
 		writeJSON(w, http.StatusOK, apiEnvelope{Data: plans})
 	})
+	if frontendDistDir != "" {
+		mux.Handle("/", frontendHandler(frontendDistDir))
+	}
 	return mux
 }
 
+func resolveFrontendDistDir() string {
+	candidates := []string{}
+	if custom := os.Getenv("FRONTEND_DIST_DIR"); custom != "" {
+		candidates = append(candidates, custom)
+	}
+
+	candidates = append(candidates,
+		filepath.Join("frontend", "dist"),
+		filepath.Join(filepath.Dir(os.Args[0]), "frontend", "dist"),
+	)
+
+	for _, candidate := range candidates {
+		indexPath := filepath.Join(candidate, "index.html")
+		info, err := os.Stat(indexPath)
+		if err == nil && !info.IsDir() {
+			return candidate
+		}
+	}
+
+	return ""
+}
+
+func frontendHandler(frontendDistDir string) http.Handler {
+	indexPath := filepath.Join(frontendDistDir, "index.html")
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet && r.Method != http.MethodHead {
+			http.NotFound(w, r)
+			return
+		}
+
+		cleanPath := path.Clean("/" + r.URL.Path)
+		if cleanPath == "/" {
+			http.ServeFile(w, r, indexPath)
+			return
+		}
+
+		relativePath := strings.TrimPrefix(cleanPath, "/")
+		assetPath := filepath.Join(frontendDistDir, filepath.FromSlash(relativePath))
+		if info, err := os.Stat(assetPath); err == nil && !info.IsDir() {
+			http.ServeFile(w, r, assetPath)
+			return
+		}
+
+		if filepath.Ext(relativePath) != "" {
+			http.NotFound(w, r)
+			return
+		}
+
+		http.ServeFile(w, r, indexPath)
+	})
+}
+
 func fetchModels(ctx context.Context, db *sql.DB) ([]modelResponse, error) {
 	rows, err := db.QueryContext(ctx, `
 		WITH latest_prices AS (