fix(receiver): harden idle-progress definition, single error frame, sendfile timeout

src/shared/file_send.c

@@ -145,7 +145,7 @@ bool file_send_sendfile_with_skip(File* file, int file_descriptor, bool use_meta
   off_t offset = 0;
   struct timespec deadline;
   clock_gettime(CLOCK_MONOTONIC, &deadline);
-  deadline.tv_sec += 60;
+  deadline.tv_sec += protocol_get_io_timeout_sec();
   while ((unsigned long long)offset < file_size) {
     struct timespec now;
     clock_gettime(CLOCK_MONOTONIC, &now);

src/shared/protocol.c

@@ -87,6 +87,12 @@ void protocol_session_set_io_timeout(ProtocolSession* session, int sec) {
   session->io_timeout_sec = sec;
 }
 
+int protocol_get_io_timeout_sec(void) {
+  const ProtocolSession* session = bound_session ? bound_session : &legacy_io_session;
+  int sec = session->io_timeout_sec;
+  return sec > 0 ? sec : RECEIVE_TIMEOUT_SEC;
+}
+
 void protocol_session_set_max_alloc(ProtocolSession* session, unsigned long long max_alloc) {
   if (!session)
     session = bound_session ? bound_session : &legacy_io_session;

src/shared/protocol.h

@@ -152,6 +152,10 @@ void protocol_session_set_max_alloc(ProtocolSession* session, unsigned long long
  * An explicit long deadline (e.g. the delete-ack wait) is applied per-call by
  * protocol_receive_status_timed and is unaffected by this setter. */
 void protocol_session_set_io_timeout(ProtocolSession* session, int sec);
+/* Effective per-message I/O deadline (seconds) for the currently-bound session,
+ * falling back to the built-in default.  Used by the plaintext sendfile path
+ * which bypasses the protocol send primitive. */
+int protocol_get_io_timeout_sec(void);
 void* protocol_alloc(size_t size);
 void* protocol_realloc(void* ptr, size_t size);
 void protocol_session_set_8_bit_output(ProtocolSession* session, bool enabled);