Fix static file read seeker guard for s0

2 files changed, 36 insertions, 1 deletions

diff --git a/internal/api/handlers.go b/internal/api/handlers.go
index b837a18..9fcb780 100644
--- a/internal/api/handlers.go
+++ b/internal/api/handlers.go
@@ -100,7 +100,12 @@ func (s *Server) serveFile(w http.ResponseWriter, r *http.Request, filename stri
 		http.Error(w, "not found", http.StatusNotFound)
 		return
 	}
-	http.ServeContent(w, r, filename, stat.ModTime(), f.(io.ReadSeeker))
+	rs, ok := f.(io.ReadSeeker)
+	if !ok {
+		http.Error(w, "internal error", http.StatusInternalServerError)
+		return
+	}
+	http.ServeContent(w, r, filename, stat.ModTime(), rs)
 }
 
 func (s *Server) serveIndex(w http.ResponseWriter, r *http.Request) {
diff --git a/internal/api/handlers_more_test.go b/internal/api/handlers_more_test.go
index 6a4353e..0403f25 100644
--- a/internal/api/handlers_more_test.go
+++ b/internal/api/handlers_more_test.go
@@ -196,6 +196,36 @@ func TestServer_ServeFile_notFound(t *testing.T) {
 	}
 }
 
+type statErrorFS struct{}
+
+func (statErrorFS) Open(string) (http.File, error) {
+	return statErrorFile{}, nil
+}
+
+type statErrorFile struct{}
+
+func (statErrorFile) Close() error { return nil }
+
+func (statErrorFile) Read([]byte) (int, error) { return 0, io.EOF }
+
+func (statErrorFile) Seek(int64, int) (int64, error) { return 0, nil }
+
+func (statErrorFile) Readdir(int) ([]os.FileInfo, error) { return nil, nil }
+
+func (statErrorFile) Stat() (os.FileInfo, error) { return nil, errors.New("stat failed") }
+
+func TestServer_ServeFile_statError(t *testing.T) {
+	srv := &Server{staticFS: statErrorFS{}}
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	rr := httptest.NewRecorder()
+
+	srv.serveFile(rr, req, "index.html")
+
+	if rr.Code != http.StatusNotFound {
+		t.Fatalf("expected %d, got %d", http.StatusNotFound, rr.Code)
+	}
+}
+
 // ------------------------------------------------------------------
 // Bootstrap negative paths
 // ------------------------------------------------------------------