diff --git a/src/services/commands/handlers/nueva.ts b/src/services/commands/handlers/nueva.ts
index 8fb1c79..47ac48e 100644
--- a/src/services/commands/handlers/nueva.ts
+++ b/src/services/commands/handlers/nueva.ts
@@ -222,7 +222,7 @@ export async function handleNueva(context: Ctx, deps: { db: Database }): Promise
   responses.push({
     recipient: createdBy,
     message: [ackLines.join('\n'), '', CTA_HELP].join('\n'),
-    mentions: mentionsForSending.length > 0 ? mentionsForSending : undefined
+    ...(mentionsForSending.length > 0 ? { mentions: mentionsForSending } : {})
   });
 
   // 2) DM a cada asignado (excluyendo al creador para evitar duplicados)
diff --git a/src/services/commands/handlers/ver.ts b/src/services/commands/handlers/ver.ts
index af68b47..c7e5022 100644
--- a/src/services/commands/handlers/ver.ts
+++ b/src/services/commands/handlers/ver.ts
@@ -64,7 +64,8 @@ export async function handleVer(context: Ctx): Promise<Msg[]> {
               : `${t.assignees!.length > 1 ? '👥' : '👤'} ${names.join(', ')}`;
           const isOverdue = t.due_date ? t.due_date < today : false;
           const datePart = t.due_date ? ` — ${isOverdue ? `${ICONS.warn} ` : ''}${ICONS.date} ${formatDDMM(t.due_date)}` : '';
-          return `- ${codeId(t.id, t.display_code)} ${t.description || '(sin descripción)'}${datePart} — ${owner}`;
+          const dc = (t as any)?.display_code as number | undefined;
+          return `- ${codeId(t.id, dc)} ${t.description || '(sin descripción)'}${datePart} — ${owner}`;
         }));
         sections.push(...rendered);
         sections.push('');
@@ -157,7 +158,8 @@ export async function handleVer(context: Ctx): Promise<Msg[]> {
           : `${t.assignees!.length > 1 ? '👥' : '👤'} ${names.join(', ')}`;
       const isOverdue = t.due_date ? t.due_date < today : false;
       const datePart = t.due_date ? ` — ${isOverdue ? `${ICONS.warn} ` : ''}${ICONS.date} ${formatDDMM(t.due_date)}` : '';
-      return `- ${codeId(t.id, t.display_code)} ${t.description || '(sin descripción)'}${datePart} — ${owner}`;
+      const dc = (t as any)?.display_code as number | undefined;
+      return `- ${codeId(t.id, dc)} ${t.description || '(sin descripción)'}${datePart} — ${owner}`;
     }));
     sections.push(...rendered);
     sections.push('');
diff --git a/src/services/group-sync.ts b/src/services/group-sync.ts
index f95a637..b345e83 100644
--- a/src/services/group-sync.ts
+++ b/src/services/group-sync.ts
@@ -229,7 +229,7 @@ export class GroupSyncService {
 			const response = await fetch(url, {
 				method: 'GET',
 				headers: {
-					apikey: process.env.EVOLUTION_API_KEY,
+					apikey: String(process.env.EVOLUTION_API_KEY || ''),
 				},
 				httpVersion: '2',
 				timeout: 320000 // 120 second timeout
@@ -252,19 +252,19 @@ export class GroupSyncService {
 			// Parse response which could be either:
 			// 1. Direct array of groups: [{group1}, {group2}]
 			// 2. Or wrapped response: {status, message, response}
-			let groups;
+			let groups: EvolutionGroup[] = [];
 			try {
 				const parsed = JSON.parse(rawResponse);
 				if (Array.isArray(parsed)) {
 					// Case 1: Direct array response
-					groups = parsed;
+					groups = parsed as EvolutionGroup[];
 					console.log('ℹ️ Received direct array of', groups.length, 'groups');
 				} else if (parsed.response && Array.isArray(parsed.response)) {
 					// Case 2: Wrapped response
 					if (parsed.status !== 'success') {
 						throw new Error(`API error: ${parsed.message || 'Unknown error'}`);
 					}
-					groups = parsed.response;
+					groups = parsed.response as EvolutionGroup[];
 					console.log('ℹ️ Received wrapped response with', groups.length, 'groups');
 				} else {
 					throw new Error('Invalid API response format - expected array or wrapped response');
@@ -344,8 +344,8 @@ export class GroupSyncService {
 	}
 
 	private static getActiveGroupsCount(): number {
-		const result = this.dbInstance.prepare('SELECT COUNT(*) as count FROM groups WHERE active = TRUE AND COALESCE(is_community,0) = 0 AND COALESCE(archived,0) = 0').get();
-		return result?.count || 0;
+		const result = this.dbInstance.prepare('SELECT COUNT(*) as count FROM groups WHERE active = TRUE AND COALESCE(is_community,0) = 0 AND COALESCE(archived,0) = 0').get() as { count?: number } | undefined;
+		return Number(result?.count || 0);
 	}
 
 	static async checkInitialGroups(): Promise<void> {
@@ -429,7 +429,7 @@ export class GroupSyncService {
 			});
 
 			for (const group of groups) {
-				const existing = this.dbInstance.prepare('SELECT 1 FROM groups WHERE id = ?').get(group.id);
+				const existing = this.dbInstance.prepare('SELECT 1 FROM groups WHERE id = ?').get((group as EvolutionGroup).id);
 				console.log('Checking group:', group.id, 'exists:', !!existing);
 
 				const isCommunityFlag = !!(((group as any)?.isCommunity) || ((group as any)?.is_community) || ((group as any)?.isCommunityAnnounce) || ((group as any)?.is_community_announce));
@@ -437,13 +437,13 @@ export class GroupSyncService {
 				if (existing) {
 					const updateResult = this.dbInstance.prepare(
 						'UPDATE groups SET name = ?, community_id = COALESCE(?, community_id), is_community = ?, active = TRUE, last_verified = CURRENT_TIMESTAMP WHERE id = ?'
-					).run(group.subject, group.linkedParent || null, isCommunityFlag ? 1 : 0, group.id);
+					).run((group as EvolutionGroup).subject, (group as EvolutionGroup).linkedParent || null, isCommunityFlag ? 1 : 0, (group as EvolutionGroup).id);
 					console.log('Updated group:', group.id, 'result:', updateResult);
 					updated++;
 				} else {
 					const insertResult = this.dbInstance.prepare(
 						'INSERT INTO groups (id, community_id, name, active, is_community) VALUES (?, ?, ?, TRUE, ?)'
-					).run(group.id, (group.linkedParent ?? ''), group.subject, isCommunityFlag ? 1 : 0);
+					).run((group as EvolutionGroup).id, (((group as EvolutionGroup).linkedParent ?? '')), (group as EvolutionGroup).subject, isCommunityFlag ? 1 : 0);
 					console.log('Added group:', group.id, 'result:', insertResult);
 					added++;
 				}
@@ -520,7 +520,7 @@ export class GroupSyncService {
 
 			const r1 = await fetch(url1, {
 				method: 'GET',
-				headers: { apikey: process.env.EVOLUTION_API_KEY },
+				headers: { apikey: String(process.env.EVOLUTION_API_KEY || '') },
 				httpVersion: '2',
 				timeout: 320000
 			});
@@ -601,7 +601,7 @@ export class GroupSyncService {
 
 		const response = await fetch(url, {
 			method: 'GET',
-			headers: { apikey: process.env.EVOLUTION_API_KEY },
+			headers: { apikey: String(process.env.EVOLUTION_API_KEY || '') },
 			httpVersion: '2',
 			timeout: 320000
 		});
diff --git a/src/services/maintenance.ts b/src/services/maintenance.ts
index c33af24..eb882e2 100644
--- a/src/services/maintenance.ts
+++ b/src/services/maintenance.ts
@@ -138,7 +138,7 @@ export class MaintenanceService {
 
     const stateUrl = `${url}/instance/connectionState/${instance}`;
     const restartUrl = `${url}/instance/restart/${instance}`;
-    const headers = { apikey: apiKey };
+    const headers: HeadersInit = { apikey: String(apiKey || '') };
 
     try {
       const response = await fetch(stateUrl, { method: 'GET', headers });