feat(companion): add disconnect metadata to connection snapshots

src/companion/runtimeClient.ts

@@ -66,6 +66,8 @@ export interface ConnectionSnapshot {
   pendingEventWaitCount: number;
   hasPendingWork: boolean;
   idle: boolean;
+  lastDisconnectCode?: number;
+  lastDisconnectReason?: string;
 }
 
 export interface ClearEventSubscriptionsResult {
@@ -313,6 +315,8 @@ export class CompanionRuntimeClient {
   private pending = new Map<number, PendingRequest>();
   private readonly eventHandlers = new Set<CompanionEventHandler>();
   private readonly pendingEventWaits = new Set<(error: Error) => void>();
+  private lastDisconnectCode: number | undefined;
+  private lastDisconnectReason: string | undefined;
 
   constructor(options: CompanionRuntimeClientOptions) {
     const requestTimeoutMs = options.requestTimeoutMs ?? 15_000;
@@ -374,6 +378,8 @@ export class CompanionRuntimeClient {
       pendingEventWaitCount: this.pendingEventWaitCount,
       hasPendingWork: this.hasPendingWork,
       idle: this.idle,
+      lastDisconnectCode: this.lastDisconnectCode,
+      lastDisconnectReason: this.lastDisconnectReason,
     };
   }
 
@@ -405,7 +411,10 @@ export class CompanionRuntimeClient {
         settled = true;
         this.ws = ws;
         this.ws.on('message', (raw) => this.handleMessage(raw.toString()));
-        this.ws.on('close', () => {
+        this.ws.on('close', (code, reason) => {
+          this.lastDisconnectCode = code;
+          const reasonText = reason?.toString().trim();
+          this.lastDisconnectReason = reasonText ? reasonText : undefined;
           if (this.ws === ws) {
             this.ws = null;
           }
@@ -445,6 +454,8 @@ export class CompanionRuntimeClient {
   }
 
   disconnect(code?: number, reason?: string): void {
+    this.lastDisconnectCode = code;
+    this.lastDisconnectReason = reason;
     if (!this.ws) {
       this.rejectEventWaits(new Error('Disconnected'));
       return;