fix: re-enable closed-loop on Sud start regardless of client

HeaterTask.shutdown() switched the heater to open-loop when a brew
ended, but nothing switched it back when a new Sud was started.  The
browser happened to send {ClosedLoop: true} as part of its UI setup,
so its connect-and-start path worked; PyQt (and any other client that
doesn't send that message) left the heater in open-loop and the TC
never drove it.

Add SudTask._on_start / set_on_start() hook, HeaterTask.start_closed_loop()
(mirror of shutdown()), and wire them in brewpi.py so the server
switches to closed-loop and broadcasts the new state to all clients the
moment any client starts a brew.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/brewpi.py

@@ -143,6 +143,9 @@ if __name__ == '__main__':
 	tc.set_on_changed("y", heater_task.actor)
 	# HeaterTask owns TC enable: enabled in closed-loop mode, disabled in open-loop.
 	heater_task.set_on_closed_loop_changed(tc.set_enabled)
+	# Brew start: switch heater to closed-loop so the TC drives it regardless
+	# of which client (browser, PyQt GUI, …) started the brew.
+	sud_task.set_on_start(heater_task.start_closed_loop)
 	# Brew end (DONE/IDLE): shut heater off and broadcast open-loop/power-0 to clients.
 	sud_task.set_on_end(heater_task.shutdown)
 

tasks/heater.py

@@ -34,6 +34,14 @@ class HeaterTask(ATask):
 		asyncio.create_task(self.send({'ClosedLoop': False}))
 		self.power_set_changed(0)
 
+	def start_closed_loop(self):
+		"""Called when a Sud starts. Re-enables closed-loop so the TC drives
+		the heater regardless of which client started the brew."""
+		self.closed_loop = True
+		if self._on_closed_loop_changed:
+			self._on_closed_loop_changed(True)
+		asyncio.create_task(self.send({'ClosedLoop': True}))
+
 	def actor(self, y):
 		self.power_actor = max(0, self.device.get_power_max() * y)
 

tasks/sud.py

@@ -111,6 +111,7 @@ class SudTask(ATask):
 		# when the current step has temperature=None (inherits from a prior step).
 		self._paused_temp_soll = None
 		self._on_end = None
+		self._on_start = None
 		self._on_plant_params = None
 		msg_handler.set_recv_handler(self.recv)
 
@@ -229,6 +230,9 @@ class SudTask(ATask):
 	def set_on_end(self, callback):
 		self._on_end = callback
 
+	def set_on_start(self, callback):
+		self._on_start = callback
+
 	def on_state_changed(self, value):
 		asyncio.create_task(self.send({'State': str(value)}))
 
@@ -450,6 +454,8 @@ class SudTask(ATask):
 					self.energy_by_step = {}
 					self._energy_index = None
 				self.sud.start()
+				if self._on_start:
+					self._on_start()
 				if fresh_start:
 					asyncio.create_task(self.send_forecast(self.sud.save()))
 				else: