diff --git a/src/agents/pi-tools.ts b/src/agents/pi-tools.ts
index 0508cda22e7..811d4708742 100644
--- a/src/agents/pi-tools.ts
+++ b/src/agents/pi-tools.ts
@@ -212,7 +212,10 @@ export function createOpenClawCodingTools(options?: {
     providerProfilePolicy,
     providerProfileAlsoAllow,
   );
-  const scopeKey = options?.exec?.scopeKey ?? (agentId ? `agent:${agentId}` : undefined);
+  // Prefer sessionKey for process isolation scope to prevent cross-session process visibility/killing.
+  // Fallback to agentId if no sessionKey is available (e.g. legacy or global contexts).
+  const scopeKey =
+    options?.exec?.scopeKey ?? options?.sessionKey ?? (agentId ? `agent:${agentId}` : undefined);
   const subagentPolicy =
     isSubagentSessionKey(options?.sessionKey) && options?.sessionKey
       ? resolveSubagentToolPolicy(options.config)