Note why the message-length header is kept off the P-ION

Tested on a P-ION (fw 1.32) at 192.168.1.252 with everything else as
in 5acca52: with the 0x81 header forced on, the app save is answered
but the app.sab file open never is, and the device drops off the
network. Without it, the same Get with File works.

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

app_backup.py

@@ -23,7 +23,6 @@ import zipfile
 
 import app_state
 import sab_app
-import sox
 from ox_widget_properties import IMAGE_EXTENSIONS, ORION_KIT, RION_KIT
 
 APP_SAB = "app.sab"
@@ -163,14 +162,12 @@ def _source_entry(media, source_path):
 def save_app(client):
     """Invokes App.save on the device and waits for it to finish.
 
-    Ontrol's Niagara driver does this before every app.sab get, resending the request
+    Ontrol's Niagara driver does this before every app.sab get.
-    only every 5 s: a P-ION saving a large app takes seconds, and 1 s resends of the
-    request while it is busy are what knocked it over.
     """
     comp = client.cache_get(0) or client.load(0)
     slots = client.slot_registry.get((comp.kit_id, comp.type_id)) or []
     slot = next((s for s in slots if s["name"] == "save" and s.get("is_action")), None)
-    client.invoke(0, slot["id"] if slot else 0, send_retry=sox.SAVE_SEND_RETRY)
+    client.invoke(0, slot["id"] if slot else 0)
 
 
 class BackupResult:

app_state.py

@@ -8,7 +8,7 @@ so later rebinding would only ever be seen by the module that did it.
 import configparser
 import os
 
-VERSION = "0.0.0.144"
+VERSION = "0.0.0.146"
 PROPERTIES_FILE = os.path.join(os.path.dirname(os.path.abspath(__file__)), "editor.properties")
 DEFAULT_GRID_SIZE = 10
 DEFAULT_ADD_TIMESTAMP = True

dasp.py

@@ -456,7 +456,7 @@ def _to_ack_more(seq_more, max_bytes):
 
 class _Packet:
     __slots__ = ("seq_num", "payload", "acked", "enqueued_time",
-                 "sent_time", "send_attempts", "send_retry", "next")
+                 "sent_time", "send_attempts", "next")
 
     def __init__(self):
         self.seq_num = 0
@@ -465,7 +465,6 @@ class _Packet:
         self.enqueued_time = 0.0
         self.sent_time = 0.0
         self.send_attempts = 1
-        self.send_retry = None      # seconds; None = the window's own interval
         self.next = None
 
 
@@ -507,17 +506,17 @@ class SendWindow:
             self._tail = None
             self._cond.notify_all()
 
-    def send(self, payload, send_retry=None):
+    def send(self, payload):
         p = _Packet()
-        p.send_retry = send_retry
         p.enqueued_time = _ticks()
+        p.payload = payload
         with self._cond:
             p.seq_num = self._seq_num & 0xFFFF
             self._seq_num = (self._seq_num + 1) & 0xFFFF
 
+        # sent_time is stamped inside the lock: send_retries() must not see the
+        # packet in the window as never sent and resend it before its first send.
         self._enqueue(p)
-        p.payload = payload
-        p.sent_time = _ticks()
         self._session._send_raw(self._to_msg(p))
 
     def _enqueue(self, p):
@@ -531,6 +530,7 @@ class SendWindow:
             else:
                 self._tail.next = p
                 self._tail = p
+            p.sent_time = _ticks()
             self._size += 1
             self._cond.notify_all()
 
@@ -620,15 +620,9 @@ class SendWindow:
             p = self._head
             while p is not None:
                 if not p.acked:
-                    if p.send_retry is not None:
+                    backoff_shift = min(p.send_attempts - 1, 32)
-                        # A request the device is slow to take -- a P-ION saving its
+                    interval = min(self.send_retry * (1 << backoff_shift),
-                        # app, opening a file -- is resent at its own steady interval:
+                                   self.max_retry_backoff)
-                        # the 1 s default resends it while the device is still busy.
-                        interval = p.send_retry
-                    else:
-                        backoff_shift = min(p.send_attempts - 1, 32)
-                        interval = min(self.send_retry * (1 << backoff_shift),
-                                       self.max_retry_backoff)
                     if now - p.sent_time >= interval:
                         self._resend(p)
                     oldest = max(oldest, now - p.enqueued_time)
@@ -784,11 +778,10 @@ class DaspSession:
 
     # ── Send / Receive ──────────────────────────────────────────
 
-    def send(self, payload, send_retry=None):
+    def send(self, payload):
-        """Queues a datagram. send_retry (seconds) overrides the resend interval."""
         if self.is_closed:
             raise DaspException(f"Session closed: {self.close_cause}")
-        self.send_window.send(payload, send_retry)
+        self.send_window.send(payload)
 
     def receive(self, timeout=1.0):
         if self.is_closed:

device_session.py

@@ -10,7 +10,6 @@ import xml.etree.ElementTree as ET
 
 import app_state
 import schema
-import sox
 from sox import SoxClient, SoxComponent, TREE, CONFIG, RUNTIME, LINKS, ALL
 
 
@@ -44,8 +43,7 @@ class DeviceSession:
 
     def connect(self, host, port, user, password):
         """DASP connect → read schema → load root. Called from background thread."""
-        self.sox_client = SoxClient(host, int(port), user, password,
+        self.sox_client = SoxClient(host, int(port), user, password)
-                                    ideal_max=sox.IDEAL_MAX, abs_max=sox.ABS_MAX)
         self.sox_client.on_event = self._on_sox_event
         self.sox_client.checksum_resolver = schema.resolve_truncated_checksum
         self.sox_client.connect()

sox.py

@@ -35,18 +35,6 @@ BUF_ID    = 7
 STR_ID    = 8
 
 
-# DASP resend intervals (seconds) for requests a device can be slow to take, as Ontrol's
-# Niagara driver sets them: a P-ION saving a large app takes 2-3+ s, and a file open can
-# take 10+ s on some devices. Resent every second instead, the device is sent copies
-# while it is still busy with the first.
-SAVE_SEND_RETRY = 5.0
-FILE_OPEN_SEND_RETRY = 15.0
-
-# The DASP packet sizes Ontrol's Niagara driver asks for in its hello.
-IDEAL_MAX = 256
-ABS_MAX = 256
-
-
 class SoxException(Exception):
     pass
 
@@ -476,8 +464,9 @@ class SoxClient:
         # Same 512-byte limit as read_schema: whatever is cut off is left
         # blank rather than failing the connect.
         platform_id = res.try_str() or ""
-        # Ontrol's message-length header is for Orion only; the Niagara driver never
+        # Ontrol's message-length header is for Orion only, as in the Niagara driver.
-        # sends it to a P-ION or R-ION.
+        # A P-ION on firmware 1.32 takes it on most requests, but a file open sent with
+        # it goes unanswered and the device drops off the network for ~20 s.
         if self._session is not None:
             self._session.include_message_len = platform_id.startswith("ontrol-orion")
         scode_flags = res.u1() if res.remaining > 0 else 0
@@ -678,13 +667,13 @@ class SoxClient:
 
     # ── Invoke Action ───────────────────────────────────────────
 
-    def invoke(self, comp_id, slot_id, type_id=None, arg=None, send_retry=None):
+    def invoke(self, comp_id, slot_id, type_id=None, arg=None):
         req = _prepare_request(ord('i'))
         req.write_u2(comp_id)
         req.write_u1(slot_id)
         if arg is not None and type_id is not None:
             encode_value(req, type_id, arg)
-        res = self.request(req, send_retry)
+        res = self.request(req)
         res.check_response('I')
 
     # ── Add Component ───────────────────────────────────────────
@@ -950,7 +939,7 @@ class SoxClient:
             opened = closed = False
             try:
                 try:
-                    res = self.request(req, FILE_OPEN_SEND_RETRY)
+                    res = self.request(req)
                 except SoxException as e:
                     # A P-ION on firmware 1.32 never answers a file get -- it drops off
                     # the network for ~20 s, as a restart would -- even for a file it
@@ -1002,21 +991,17 @@ class SoxClient:
 
     # ── Networking ──────────────────────────────────────────────
 
-    def request(self, req, send_retry=None):
+    def request(self, req):
-        results = self.requests([req], send_retry)
+        results = self.requests([req])
         return results[0]
 
-    def requests(self, reqs, send_retry=None):
+    def requests(self, reqs):
-        """Sends the batch and waits for every reply.
+        """Sends the batch and waits for every reply."""
-
-        send_retry (seconds) sets the DASP resend interval of these datagrams, for a
-        request the device is known to be slow to take.
-        """
         if self.is_closed:
             raise SoxException("SoxClient closed")
 
         if len(reqs) > 255:
-            return self._chunk_requests(reqs, send_retry)
+            return self._chunk_requests(reqs)
 
         with self._lock:
             for i, req in enumerate(reqs):
@@ -1027,7 +1012,7 @@ class SoxClient:
             self._req_event.clear()
 
             for req in reqs:
-                self._session.send(req.to_bytes(), send_retry)
+                self._session.send(req.to_bytes())
 
             deadline = time.monotonic() + 30.0
             while True:
@@ -1051,11 +1036,11 @@ class SoxClient:
             self._responses = None
             raise SoxException("Request timeout")
 
-    def _chunk_requests(self, reqs, send_retry=None):
+    def _chunk_requests(self, reqs):
         results = []
         for i in range(0, len(reqs), 255):
             chunk = reqs[i:i + 255]
-            results.extend(self.requests(chunk, send_retry))
+            results.extend(self.requests(chunk))
         return results
 
     # called by receiver thread