aioble/server: Make singleton service re-registration safe.

Preserve _initial across re-registration instead of consuming it.
Invalidate characteristic handles and wake blocked written() callers
on server shutdown. Auto-rebuild capture infrastructure in
register_services() when capture-enabled characteristics are present.

Signed-off-by: Andrew Langmeier <andrew.langmeier@planetinnovation.com>

Author: pi-anl

micropython/bluetooth/aioble/aioble/server.py

@@ -15,7 +15,7 @@
     register_irq_handler,
     GattError,
 )
-from .device import DeviceConnection, DeviceTimeout
+from .device import DeviceConnection, DeviceDisconnectedError, DeviceTimeout
 
 _registered_characteristics = {}
 
@@ -56,6 +56,10 @@ def _server_irq(event, data):
 
 def _server_shutdown():
     global _registered_characteristics
+    for characteristic in _registered_characteristics.values():
+        if hasattr(characteristic, "_write_event"):
+            characteristic._write_event.set()
+        characteristic._value_handle = None
     _registered_characteristics = {}
     if hasattr(BaseCharacteristic, "_capture_task"):
         BaseCharacteristic._capture_task.cancel()
@@ -84,7 +88,6 @@ def _register(self, value_handle):
         _registered_characteristics[value_handle] = self
         if self._initial is not None:
             self.write(self._initial)
-            self._initial = None
 
     # Read value from local db.
     def read(self):
@@ -152,6 +155,9 @@ async def written(self, timeout_ms=None):
         with DeviceTimeout(None, timeout_ms):
             await self._write_event.wait()
 
+        if self._value_handle is None:
+            raise DeviceDisconnectedError()
+
         # Return the write data and clear the stored copy.
         # In default usage this will be just the connection handle.
         # In capture mode this will be a tuple of (connection_handle, received_data)
@@ -338,3 +344,8 @@ def register_services(*services):
             for descriptor in characteristic.descriptors:
                 descriptor._register(service_handles[n])
                 n += 1
+
+    for characteristic in _registered_characteristics.values():
+        if characteristic.flags & _FLAG_WRITE_CAPTURE:
+            BaseCharacteristic._init_capture()
+            break