feat: usar arranque como último cambio e introducir métrica de edad

Co-authored-by: aider (openrouter/openai/gpt-5) <aider@aider.chat>

src/services/maintenance.ts

@@ -9,6 +9,7 @@ export class MaintenanceService {
   private static _lastRestartAttempt: number = 0;
   private static _lastEvolutionState: string | null = null;
   private static _lastStateChangeTs: number = 0;
+  private static readonly _processStartSec: number = Math.floor(Date.now() / 1000);
 
   private static get retentionDays(): number {
     const v = Number(process.env.GROUP_MEMBERS_INACTIVE_RETENTION_DAYS);
@@ -160,8 +161,8 @@ export class MaintenanceService {
       // Logging solo en primer muestreo o cuando cambie
       if (!prev) {
         console.log(`[HealthCheck] Estado inicial de la instancia '${instance}': ${newState}`);
-        this._lastStateChangeTs = nowSec;
+        this._lastStateChangeTs = this._processStartSec;
-        try { Metrics.set('evolution_instance_last_state_change_ts', nowSec, { instance: String(instance || '') }); } catch {}
+        try { Metrics.set('evolution_instance_last_state_change_ts', this._processStartSec, { instance: String(instance || '') }); } catch {}
       } else if (prev !== newState) {
         console.log(`[HealthCheck] Cambio de estado en instancia '${instance}': ${prev} → ${newState}`);
         this._lastStateChangeTs = nowSec;
@@ -172,6 +173,9 @@ export class MaintenanceService {
       }
 
       this._lastEvolutionState = newState;
+      try {
+        Metrics.set('evolution_instance_state_age_seconds', Math.max(0, nowSec - this._lastStateChangeTs), { instance: String(instance || '') });
+      } catch {}
     };
 
     try {