diff --git a/src/mcp/registry.py b/src/mcp/registry.py
index 5e6d047..aa1460a 100644
--- a/src/mcp/registry.py
+++ b/src/mcp/registry.py
@@ -8,6 +8,7 @@ defines the project-specific variables (ACAI_WEB_URL, etc.).
 from __future__ import annotations
 
 import logging
+import time
 from pathlib import Path
 from typing import Any
 
@@ -17,6 +18,15 @@ from .manager import MCPManager
 
 logger = logging.getLogger(__name__)
 
+# Máximo de sesiones MCP vivas a la vez. Cada sesión arranca N subprocesos
+# stdio (acai-code, playwright+chromium, fetch) con sus read-loops en el event
+# loop; si se acumulan sin límite, saturan recursos y DEGRADAN progresivamente
+# las sesiones nuevas (menos contexto/tools al modelo, hasta que el agente deja
+# de recibir tools y emite los tool calls como texto). Evictamos por LRU las
+# menos usadas — es seguro porque send_message reconecta el MCP de una sesión
+# si vuelve a usarse y ya no está viva.
+MAX_ACTIVE_MCP_SESSIONS = 2
+
 
 class MCPRegistry:
     """Manages per-session MCPManager instances.
@@ -29,6 +39,7 @@ class MCPRegistry:
         self._config_path = Path(config_path) if config_path else None
         self._config: MCPConfigFile | None = None
         self._sessions: dict[str, MCPManager] = {}  # session_id → MCPManager
+        self._last_used: dict[str, float] = {}  # session_id → monotonic ts (LRU)
 
     def load_config(self) -> None:
         """Load the global MCP config template."""
@@ -91,6 +102,7 @@ class MCPRegistry:
 
         results = await manager.start()
         self._sessions[session_id] = manager
+        self._last_used[session_id] = time.monotonic()
 
         logger.info(
             "MCP started for session %s: %s",
@@ -98,18 +110,41 @@ class MCPRegistry:
             {k: v.get("status") for k, v in results.items()},
         )
 
+        # Evictar por LRU si superamos el máximo (evita la degradación por
+        # acumulación de subprocesos MCP). Seguro: send_message reconecta.
+        await self._evict_lru()
+
         return manager
 
+    async def _evict_lru(self) -> None:
+        """Destruye las sesiones MCP menos usadas recientemente hasta no superar
+        MAX_ACTIVE_MCP_SESSIONS."""
+        while len(self._sessions) > MAX_ACTIVE_MCP_SESSIONS:
+            # sesión con last_used más antiguo (las que no tienen ts van primero)
+            oldest = min(
+                self._sessions.keys(),
+                key=lambda sid: self._last_used.get(sid, 0.0),
+            )
+            logger.info(
+                "MCP registry: evicting LRU session %s (%d active > max %d)",
+                oldest[:12], len(self._sessions), MAX_ACTIVE_MCP_SESSIONS,
+            )
+            await self.destroy_for_session(oldest)
+
     async def destroy_for_session(self, session_id: str) -> None:
         """Stop and clean up MCP servers for a session."""
         manager = self._sessions.pop(session_id, None)
+        self._last_used.pop(session_id, None)
         if manager:
             await manager.stop()
             logger.info("MCP stopped for session %s", session_id[:12])
 
     def get_for_session(self, session_id: str) -> MCPManager | None:
         """Get the MCPManager for a session, if any."""
-        return self._sessions.get(session_id)
+        manager = self._sessions.get(session_id)
+        if manager is not None:
+            self._last_used[session_id] = time.monotonic()  # touch LRU
+        return manager
 
     async def stop_all(self) -> None:
         """Stop all sessions' MCP servers (shutdown)."""