Add Closed-loop/Open-loop heater control mode

Closed-loop (default, checkbox checked): TC has exclusive control over
the heater; temp-soll and heatrate-soll sliders are active; direct
heater power entry is disabled. TC now stays enabled at server startup
and whenever closed-loop mode is active — SudTask no longer disables it
on IDLE/DONE, so adjusting temp-soll manually with no sud running
immediately drives the heater via the TC.

Open-loop (checkbox unchecked, only selectable when paused/stopped):
TC is disconnected from the heater; only the heater-power slider is
active. Switching back to closed-loop resets power_soll to 0 and
re-enables the TC.

On play, the mode is automatically reset to closed-loop.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SH2D4LRuCnhLSzoYerAfJX

web/app.js

@@ -37,6 +37,9 @@ let warpFactor = 1.0;
 let heaterPowerIst = 0;
 let heaterPowerSoll = 0;
 let heaterMaxPower = 100;
+// Closed-loop: TC drives heater exclusively. Open-loop: direct power_soll only.
+// Only switchable when not running; auto-reset to true on play.
+let closedLoop = true;
 
 // Sud state - mirrors the sud_* fields on client/brewpi_gui.py's Window.
 let sudSchedule = [];
@@ -468,6 +471,19 @@ function updateStatusLine() {
 	el.textContent = `${text}   ${elapsedText}   ${energyText}`;
 }
 
+// Enables/disables sliders and the closed-loop checkbox based on mode and sud state.
+// TC sliders (temp/heatrate): only when closed-loop and not running.
+// Heater power slider: only when open-loop and not running.
+// Stirrer: whenever not running. Checkbox: whenever not running.
+function updateControlsEnabled() {
+	const sudRunning = RUNNING_STATES.has(sudState);
+	document.getElementById('temp-soll').disabled = !closedLoop;
+	document.getElementById('heatrate-soll').disabled = !closedLoop;
+	document.getElementById('heater-power').disabled = !(!closedLoop && !sudRunning);
+	document.getElementById('stirrer-speed').disabled = sudRunning;
+	document.getElementById('closed-loop').disabled = sudRunning;
+}
+
 // Mirrors client/brewpi_gui.py's update_sud_actions(): Start also doubles
 // as Resume while paused; Stop can still abort a paused run.
 function updateSudActions() {
@@ -555,6 +571,10 @@ function onHeaterChanged(msg) {
 		} else if (key === 'Power') {
 			heaterPowerIst = msg.Power;
 			document.getElementById('lcd-power-ist').textContent = msg.Power;
+		} else if (key === 'ClosedLoop') {
+			closedLoop = msg.ClosedLoop;
+			document.getElementById('closed-loop').checked = closedLoop;
+			updateControlsEnabled();
 		} else if (key === 'Capabilities') {
 			const power = msg.Capabilities.Power;
 			heaterMaxPower = power.Max || 100;
@@ -649,16 +669,16 @@ function onSudChanged(msg) {
 			const prevState = sudState;
 			const isRunningNow = RUNNING_STATES.has(newState);
 			if (isRunningNow && !wasRunning) {
+				closedLoop = true;
+				document.getElementById('closed-loop').checked = true;
+				sendMsg('Heater', {ClosedLoop: true});
 				elapsed = 0;
 				energyByStep = {};
 				energyCurrent = 0;
 			}
 			wasRunning = isRunningNow;
 			sudState = newState;
-			const sliderDisabled = RUNNING_STATES.has(sudState);
-			for (const id of ['temp-soll', 'heatrate-soll', 'heater-power', 'stirrer-speed']) {
-				document.getElementById(id).disabled = sliderDisabled;
-			}
+			updateControlsEnabled();
 			if (newState === WAIT_USER_STATE && prevState !== WAIT_USER_STATE && sudUserMessage) {
 				showUserMessage(sudUserMessage);
 			} else if (prevState === WAIT_USER_STATE && newState !== WAIT_USER_STATE) {
@@ -771,6 +791,7 @@ function connect() {
 		initialHeatrateSync = true;
 		initialTempSollSync = true;
 		initialPotTempSync = true;
+		closedLoop = true;
 		setConnected(true);
 		for (const channel of CHANNELS) {
 			ws.send(JSON.stringify({'+': channel}));
@@ -786,7 +807,7 @@ function connect() {
 		statusEl.className = 'status-disconnected';
 	};
 	ws.onclose = () => {
-		for (const id of ['temp-soll', 'heatrate-soll', 'heater-power', 'stirrer-speed']) {
+		for (const id of ['temp-soll', 'heatrate-soll', 'heater-power', 'stirrer-speed', 'closed-loop']) {
 			document.getElementById(id).disabled = false;
 		}
 		setConnected(false);
@@ -820,6 +841,9 @@ document.getElementById('btn-connect').addEventListener('click', () => {
 	}
 });
 
+document.getElementById('closed-loop').addEventListener('change', (e) => {
+	sendMsg('Heater', {ClosedLoop: e.target.checked});
+});
 document.getElementById('heater-power').addEventListener('input', (e) => {
 	document.getElementById('heater-power-readout').textContent = e.target.value;
 	sendMsg('Heater', {Power: Number(e.target.value)});

web/index.html

@@ -43,6 +43,9 @@
 	</div>
 	<div class="panel">
 		<h3>Heater</h3>
+		<label class="checkbox-label">
+			<input type="checkbox" id="closed-loop" checked> Closed-loop
+		</label>
 		<label>Power [W]
 			<div class="slider-row">
 				<input type="range" id="heater-power" min="0" max="100" step="1">

web/style.css

@@ -289,6 +289,7 @@ header#connection-bar {
 }
 .slider-row input[type="range"] { flex: 1; accent-color: var(--accent); }
 .panel input[type="checkbox"] { accent-color: var(--accent); width: 15px; height: 15px; }
+.panel label.checkbox-label { flex-direction: row; align-items: center; gap: 0.5em; cursor: pointer; }
 .panel input[type="number"]   { width: 6em; }
 
 #pot-reset-row { display: flex; align-items: center; gap: 0.6em; margin: 0.4em 0; }