From e5126c913d8af2201852745ae7107f41c973ce4d Mon Sep 17 00:00:00 2001
From: Zoe Forbes <forbes@copernicus-9.kindred.internal>
Date: Sun, 8 Feb 2026 15:36:04 -0600
Subject: [PATCH] fix: SSE reconnect with exponential backoff and terminal
 state

Replace the infinite fixed-delay retry loop with exponential backoff
(1s, 2s, 4s, ... capped at 60s) and a max retry limit of 10.

Changes to SiloEventListener:
- Expand connection_status signal to (status, retry_count, error_message)
- Add exponential backoff: min(BASE_DELAY * 2^retries, MAX_DELAY)
- Add terminal "gave_up" state after MAX_RETRIES exhausted
- Capture and forward error messages from failed connection attempts

Changes to SiloAuthDockWidget._on_sse_status:
- Show retry count: "Reconnecting (3/10)..."
- Show "Disconnected" (red) on gave_up state
- Log each attempt to FreeCAD console (PrintWarning/PrintError)
- Set tooltip with last error message on the status label

Closes #2
---
 freecad/silo_commands.py | 51 +++++++++++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 16 deletions(-)

diff --git a/freecad/silo_commands.py b/freecad/silo_commands.py
index aad817c..649b9d2 100644
--- a/freecad/silo_commands.py
+++ b/freecad/silo_commands.py
@@ -2365,13 +2365,13 @@ class SiloEventListener(QtCore.QThread):
     item_updated = QtCore.Signal(str)  # part_number
     revision_created = QtCore.Signal(str, int)  # part_number, revision
     connection_status = QtCore.Signal(
-        str
-    )  # "connected" / "disconnected" / "unsupported"
+        str, int, str
+    )  # (status, retry_count, error_message)
     server_mode_changed = QtCore.Signal(str)  # "normal" / "read-only" / "degraded"
 
-    _MAX_FAST_RETRIES = 3
-    _FAST_RETRY_SECS = 5
-    _SLOW_RETRY_SECS = 30
+    _MAX_RETRIES = 10
+    _BASE_DELAY = 1  # seconds, doubles each retry
+    _MAX_DELAY = 60  # seconds, backoff cap
 
     def __init__(self, parent=None):
         super().__init__(parent)
@@ -2394,6 +2394,7 @@ class SiloEventListener(QtCore.QThread):
 
     def run(self):
         retries = 0
+        last_error = ""
         while not self._stop_flag:
             try:
                 self._listen()
@@ -2401,21 +2402,24 @@ class SiloEventListener(QtCore.QThread):
                 if self._stop_flag:
                     return
                 retries += 1
+                last_error = "connection closed"
             except _SSEUnsupported:
-                self.connection_status.emit("unsupported")
+                self.connection_status.emit("unsupported", 0, "")
                 return
-            except Exception:
+            except Exception as exc:
                 retries += 1
+                last_error = str(exc) or "unknown error"
 
-            self.connection_status.emit("disconnected")
+            if retries > self._MAX_RETRIES:
+                self.connection_status.emit("gave_up", retries - 1, last_error)
+                return
 
-            if retries <= self._MAX_FAST_RETRIES:
-                delay = self._FAST_RETRY_SECS
-            else:
-                delay = self._SLOW_RETRY_SECS
+            self.connection_status.emit("disconnected", retries, last_error)
+
+            delay = min(self._BASE_DELAY * (2 ** (retries - 1)), self._MAX_DELAY)
 
             # Interruptible sleep
-            for _ in range(delay):
+            for _ in range(int(delay)):
                 if self._stop_flag:
                     return
                 self.msleep(1000)
@@ -2439,7 +2443,7 @@ class SiloEventListener(QtCore.QThread):
         except urllib.error.URLError:
             raise
 
-        self.connection_status.emit("connected")
+        self.connection_status.emit("connected", 0, "")
 
         event_type = ""
         data_buf = ""
@@ -2705,13 +2709,28 @@ class SiloAuthDockWidget:
                 self._event_listener.stop()
             self._sse_label.setText("")
 
-    def _on_sse_status(self, status):
+    def _on_sse_status(self, status, retry, error):
         if status == "connected":
             self._sse_label.setText("Listening")
             self._sse_label.setStyleSheet("font-size: 11px; color: #4CAF50;")
+            self._sse_label.setToolTip("")
+            FreeCAD.Console.PrintMessage("Silo: SSE connected\n")
         elif status == "disconnected":
-            self._sse_label.setText("Reconnecting...")
+            self._sse_label.setText(
+                f"Reconnecting ({retry}/{SiloEventListener._MAX_RETRIES})..."
+            )
             self._sse_label.setStyleSheet("font-size: 11px; color: #FF9800;")
+            self._sse_label.setToolTip(error or "Connection lost")
+            FreeCAD.Console.PrintWarning(
+                f"Silo: SSE reconnecting ({retry}/{SiloEventListener._MAX_RETRIES}): {error}\n"
+            )
+        elif status == "gave_up":
+            self._sse_label.setText("Disconnected")
+            self._sse_label.setStyleSheet("font-size: 11px; color: #F44336;")
+            self._sse_label.setToolTip(error or "Max retries reached")
+            FreeCAD.Console.PrintError(
+                f"Silo: SSE gave up after {retry} retries: {error}\n"
+            )
         elif status == "unsupported":
             self._sse_label.setText("Not available")
             self._sse_label.setStyleSheet("font-size: 11px; color: #888;")