refactor(agent): require explicit send options

packages/core/agent-loop/tests/loop.spec.ts

@@ -42,7 +42,7 @@ function waitForIdle(ctx: Context, agent: Agent): Promise<void> {
 }
 
 function send(agent: Agent, text: string) {
-  agent.send([{ type: 'text', text }])
+  agent.followup([{ type: 'text', text }])
 }
 
 describe('agent loop', () => {
@@ -1068,9 +1068,9 @@ describe('agent loop', () => {
     const agent = ctx.agentLoop.create(SessionId('a1'), { provider: 'mock', model: 'mock' })
 
     const idle = waitForIdle(ctx, agent)
-    agent.send([{ type: 'text', text: 'user message' }])
+    agent.followup([{ type: 'text', text: 'user message' }])
     await Promise.resolve()
-    agent.send(
+    agent.followup(
       [{ type: 'text', text: 'plugin message' }],
       { source: { kind: 'plugin', plugin: 'test' } },
     )