fix(exec): apply per-agent exec defaults for opaque session keys

Co-authored-by: brin-tapcart <brin-tapcart@users.noreply.github.com>

src/agents/cli-runner.ts

@@ -96,6 +96,7 @@ export async function runCliAgent(params: {
   const { defaultAgentId, sessionAgentId } = resolveSessionAgentIds({
     sessionKey: params.sessionKey,
     config: params.config,
+    agentId: params.agentId,
   });
   const heartbeatPrompt =
     sessionAgentId === defaultAgentId