fix: production hardening — safety fixes, prediction accuracy, test coverage

Safety:
- Async input handler: await all handleInput() calls, prevents unhandled rejections
- Fix emergencyStop case mismatch: "emergencyStop" → "emergencystop" matching config
- Implement showCoG() method (was routing to undefined)
- Null guards on 6 methods for missing curve data
- Editor menu polling timeout (5s max)
- Listener cleanup on node close (child measurements + state emitter)
- Tick loop race condition: track startup timeout, clear on close

Prediction accuracy:
- Remove efficiency rounding that destroyed signal in canonical units
- Fix calcEfficiency variant: hydraulic power reads from correct variant
- Guard efficiency calculations against negative/zero values
- Division-by-zero protection in calcRelativeDistanceFromPeak
- Curve data anomaly detection (cross-pressure median-y ratio check)
- calcEfficiencyCurve O(n²) → O(n) with running min
- updateCurve bootstraps predictors when they were null

Tests: 43 new tests (76 total) covering emergency stop, shutdown/maintenance
sequences, efficiency/CoG, movement lifecycle, output format, null guards,
and listener cleanup.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

test/integration/efficiency-cog.integration.test.js

@@ -0,0 +1,147 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+
+const Machine = require('../../src/specificClass');
+const { makeMachineConfig, makeStateConfig } = require('../helpers/factories');
+
+function makePressurizedOperationalMachine() {
+  const machine = new Machine(makeMachineConfig(), makeStateConfig({ state: { current: 'operational' } }));
+  machine.updateMeasuredPressure(800, 'upstream', { timestamp: Date.now(), unit: 'mbar', childName: 'pt-up' });
+  machine.updateMeasuredPressure(1200, 'downstream', { timestamp: Date.now(), unit: 'mbar', childName: 'pt-down' });
+  return machine;
+}
+
+test('calcCog returns valid peak efficiency and index', () => {
+  const machine = makePressurizedOperationalMachine();
+
+  const result = machine.calcCog();
+
+  assert.ok(Number.isFinite(result.cog), 'cog should be finite');
+  assert.ok(result.cog > 0, 'peak efficiency should be positive');
+  assert.ok(Number.isFinite(result.cogIndex), 'cogIndex should be finite');
+  assert.ok(result.cogIndex >= 0, 'cogIndex should be non-negative');
+  assert.ok(Number.isFinite(result.NCog), 'NCog should be finite');
+  assert.ok(result.NCog >= 0 && result.NCog <= 1, 'NCog should be between 0 and 1');
+  assert.ok(Number.isFinite(result.minEfficiency), 'minEfficiency should be finite');
+  assert.ok(result.minEfficiency >= 0, 'minEfficiency should be non-negative');
+});
+
+test('calcCog peak is always >= minEfficiency', () => {
+  const machine = makePressurizedOperationalMachine();
+
+  const result = machine.calcCog();
+  assert.ok(result.cog >= result.minEfficiency, 'Peak must be >= min');
+});
+
+test('calcEfficiencyCurve produces correct specific flow ratio', () => {
+  const machine = makePressurizedOperationalMachine();
+  const { powerCurve, flowCurve } = machine.getCurrentCurves();
+
+  const { efficiencyCurve, peak, peakIndex, minEfficiency } = machine.calcEfficiencyCurve(powerCurve, flowCurve);
+
+  assert.ok(efficiencyCurve.length > 0, 'Efficiency curve should not be empty');
+  assert.equal(efficiencyCurve.length, powerCurve.y.length, 'Should match curve length');
+
+  // Verify each point: efficiency = flow / power (unrounded, canonical units)
+  for (let i = 0; i < efficiencyCurve.length; i++) {
+    const power = powerCurve.y[i];
+    const flow = flowCurve.y[i];
+    if (power > 0 && flow >= 0) {
+      const expected = flow / power;
+      assert.ok(Math.abs(efficiencyCurve[i] - expected) < 1e-12, `Mismatch at index ${i}`);
+    }
+  }
+
+  // Peak should be the max
+  const actualMax = Math.max(...efficiencyCurve);
+  assert.equal(peak, actualMax, 'Peak should match max of efficiency curve');
+  assert.equal(efficiencyCurve[peakIndex], peak, 'peakIndex should point to peak value');
+  assert.equal(minEfficiency, Math.min(...efficiencyCurve), 'minEfficiency should match min');
+});
+
+test('calcEfficiencyCurve handles empty curves gracefully', () => {
+  const machine = new Machine(makeMachineConfig(), makeStateConfig({ state: { current: 'operational' } }));
+
+  const result = machine.calcEfficiencyCurve({ x: [], y: [] }, { x: [], y: [] });
+
+  assert.deepEqual(result.efficiencyCurve, []);
+  assert.equal(result.peak, 0);
+  assert.equal(result.peakIndex, 0);
+  assert.equal(result.minEfficiency, 0);
+});
+
+test('calcDistanceBEP returns absolute and relative distances', () => {
+  const machine = makePressurizedOperationalMachine();
+
+  const efficiency = 5;
+  const maxEfficiency = 10;
+  const minEfficiency = 2;
+
+  const result = machine.calcDistanceBEP(efficiency, maxEfficiency, minEfficiency);
+
+  assert.ok(Number.isFinite(result.absDistFromPeak), 'abs distance should be finite');
+  assert.equal(result.absDistFromPeak, Math.abs(efficiency - maxEfficiency));
+  assert.ok(Number.isFinite(result.relDistFromPeak), 'rel distance should be finite');
+});
+
+test('calcRelativeDistanceFromPeak returns 1 when maxEfficiency equals minEfficiency', () => {
+  const machine = makePressurizedOperationalMachine();
+
+  const result = machine.calcRelativeDistanceFromPeak(5, 5, 5);
+  assert.equal(result, 1, 'Should return default distance when max==min (division by zero guard)');
+});
+
+test('showCoG returns structured data with curve guards', () => {
+  const machine = makePressurizedOperationalMachine();
+
+  const result = machine.showCoG();
+
+  assert.ok('cog' in result);
+  assert.ok('cogIndex' in result);
+  assert.ok('NCog' in result);
+  assert.ok('NCogPercent' in result);
+  assert.ok('minEfficiency' in result);
+  assert.ok('currentEfficiencyCurve' in result);
+  assert.ok(result.cog > 0);
+  assert.equal(result.NCogPercent, Math.round(result.NCog * 100 * 100) / 100);
+});
+
+test('showCoG returns safe fallback when no curve is available', () => {
+  const machine = new Machine(
+    makeMachineConfig({ asset: { model: null } }),
+    makeStateConfig()
+  );
+
+  const result = machine.showCoG();
+  assert.equal(result.cog, 0);
+  assert.ok('error' in result);
+});
+
+test('showWorkingCurves returns safe fallback when no curve is available', () => {
+  const machine = new Machine(
+    makeMachineConfig({ asset: { model: null } }),
+    makeStateConfig()
+  );
+
+  const result = machine.showWorkingCurves();
+  assert.ok('error' in result);
+});
+
+test('efficiency output fields are present in getOutput', () => {
+  const machine = makePressurizedOperationalMachine();
+
+  // Move to a position so predictions produce values
+  machine.state.transitionToState('operational');
+  machine.updatePosition();
+
+  const output = machine.getOutput();
+
+  assert.ok('cog' in output);
+  assert.ok('NCog' in output);
+  assert.ok('NCogPercent' in output);
+  assert.ok('effDistFromPeak' in output);
+  assert.ok('effRelDistFromPeak' in output);
+  assert.ok('predictionQuality' in output);
+  assert.ok('predictionConfidence' in output);
+  assert.ok('predictionPressureSource' in output);
+});