fix(web): the title-part hang-up is handled like the rest, and an abandoned request is answered 499, not an implicit 200 (fourth review)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/web/uploads.go

@@ -95,7 +95,7 @@ func (a *App) handleUploadPost(w http.ResponseWriter, r *http.Request) {
 		}
 		if err != nil {
 			var tooBig *http.MaxBytesError
-			if a.abandoned(r) {
+			if a.abandoned(w, r) {
 				return
 			}
 			if !errors.As(err, &tooBig) {
@@ -113,6 +113,9 @@ func (a *App) handleUploadPost(w http.ResponseWriter, r *http.Request) {
 		case "title":
 			b, err := io.ReadAll(io.LimitReader(part, maxTitleRunes*utf8.UTFMax))
 			if err != nil {
+				if a.abandoned(w, r) {
+					return
+				}
 				a.renderUploadsPage(w, r, userID, http.StatusBadRequest, "That upload could not be read. Please try again.")
 				return
 			}
@@ -133,14 +136,17 @@ func (a *App) handleUploadPost(w http.ResponseWriter, r *http.Request) {
 	a.renderUploadsPage(w, r, userID, http.StatusBadRequest, "Choose an audio file to upload.")
 }
 
-// abandoned reports, and logs at INFO, that the client has already gone: its request
+// abandoned reports, logs at INFO and answers 499, because the client has already gone: its request
 // context is cancelled, so there is nobody to answer and rendering a page would run its
 // database read on a dead context and log a false ERROR. A hang-up mid-upload is routine.
-func (a *App) abandoned(r *http.Request) bool {
+func (a *App) abandoned(w http.ResponseWriter, r *http.Request) bool {
 	if r.Context().Err() == nil {
 		return false
 	}
 	a.logger().Info("upload abandoned", "reason", "client_gone")
+	// 499 (the "client closed request" convention): a client that half-closed after sending
+	// can still read, and an unwritten status would reach it as a false, empty 200.
+	w.WriteHeader(499)
 	return true
 }
 
@@ -148,7 +154,7 @@ func (a *App) abandoned(r *http.Request) bool {
 // rejection is the user's to fix (422, or 413 for size) and carries its own
 // message; anything else is ours.
 func (a *App) uploadFailure(w http.ResponseWriter, r *http.Request, userID string, err error) {
-	if a.abandoned(r) {
+	if a.abandoned(w, r) {
 		return
 	}
 	var rej *uploads.RejectError