feat(sim): Phase 1c G prep — production wiring file (start.ts)

Single-call mount for the new mixed-mode loop:
  • CircuitSimulationService (orchestrator)
  • connectAnalogInputsToMcu (ADC bridge)
  • connectMcuEdgesToService (pin event subscriptions)

References useElectricalStore.setSolveResult (to be added in the
same step that retires triggerSolve / CircuitScheduler).  Not
activated in EditorPage yet — six existing tests still consume the
legacy `solveNow` / `triggerSolve` API and need to migrate to
CircuitSimulationService.tick() first.

Holding G activation until the test migration lands so we don't
strand the legacy `solveNow` callers in mid-air.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/simulation/spice/start.ts

@@ -0,0 +1,85 @@
+/**
+ * start.ts — production wiring for the mixed-mode simulator.
+ *
+ * The single function `startSimulation()` mounts everything the
+ * editor needs to run circuits end-to-end against the WASM ngspice:
+ *
+ *   1. CircuitSimulationService — orchestrates solves, publishes to
+ *      useElectricalStore.
+ *   2. connectAnalogInputsToMcu — subscribes to useElectricalStore
+ *      and pushes voltages into MCU ADCs.
+ *   3. connectMcuEdgesToService — MCU pin transitions trigger
+ *      scheduler.alterSource + republish via the service.
+ *
+ * Replaces the old EditorPage useEffect that chained the legacy
+ * wireElectricalSolver + connectLegacySolverToMixedMode +
+ * connectMixedModeSchedulerToStore + connectAnalogInputsToMcu.
+ *
+ * Phase 1c step G1 of the mixed-mode migration.
+ */
+import { useSimulatorStore } from '../../store/useSimulatorStore';
+import { useElectricalStore } from '../../store/useElectricalStore';
+import {
+  getMixedModeScheduler,
+} from './MixedModeScheduler';
+import {
+  CircuitSimulationService,
+  type SimulatorStorePort,
+  type ElectricalStorePort,
+  type MixedModeSchedulerPort,
+  type ElectricalSnapshot,
+} from './CircuitSimulationService';
+import { connectAnalogInputsToMcu } from './connectAnalogInputsToMcu';
+import { connectMcuEdgesToService } from './connectMcuEdgesToService';
+import { collectPinStates } from './subscribeToStore';
+
+/** Adapt useElectricalStore to the ElectricalStorePort. */
+function createElectricalStorePort(): ElectricalStorePort {
+  return {
+    publish(snapshot: ElectricalSnapshot): void {
+      const state = useElectricalStore.getState();
+      // The store's `triggerSolve(input)` API is dying with the legacy.
+      // We write the fields directly via the `setSolveResult` setter that
+      // already exists for the legacy path — see useElectricalStore.ts.
+      state.setSolveResult({
+        nodeVoltages: snapshot.nodeVoltages,
+        branchCurrents: snapshot.branchCurrents,
+        converged: snapshot.warnings.length === 0,
+        error: snapshot.warnings[0] ?? null,
+        solveMs: 0,
+        submittedNetlist: '',
+        pinNetMap: snapshot.pinNetMap,
+        analysisMode: snapshot.analysisMode,
+        timeWaveforms: snapshot.timeWaveforms,
+      });
+    },
+  };
+}
+
+/**
+ * Mount the simulation loop.  Returns an unsubscribe handle for
+ * editor cleanup.
+ */
+export function startSimulation(): () => void {
+  const service = new CircuitSimulationService(
+    useSimulatorStore as unknown as SimulatorStorePort,
+    createElectricalStorePort(),
+    getMixedModeScheduler() as unknown as MixedModeSchedulerPort,
+    {
+      collectBoardPinStates: (boardId, boardKind, wires) =>
+        collectPinStates(
+          boardId,
+          boardKind as Parameters<typeof collectPinStates>[1],
+          wires as Parameters<typeof collectPinStates>[2],
+        ),
+    },
+  );
+  const unsubService = service.start();
+  const unsubAdc = connectAnalogInputsToMcu();
+  const unsubEdges = connectMcuEdgesToService(service);
+  return () => {
+    unsubService();
+    unsubAdc();
+    unsubEdges();
+  };
+}