refactor(agent): align delivery method names

examples/headless-agent/tests/code-mode.e2e.ts

@@ -311,7 +311,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('Code Mode: real model writes a p
     ctx = await codeModeHarness(workdir)
     const agent = ctx.agentLoop.create(SessionId('e2e-code-mode'), { provider: 'deepseek', model: 'deepseek-v4-flash' })
 
-    agent.send([{
+    agent.followup([{
       type: 'text',
       text: 'Using one run_code program: run `echo alpha-7` with the bash tool, run `echo beta-9` with the bash tool, '
         + 'then write both outputs joined by a plus sign into combined.txt (bash heredoc or redirect), '
@@ -363,7 +363,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('Code Mode: real model writes a p
       agentOptions: { provider: 'deepseek', model: 'deepseek-v4-flash' },
     })
 
-    handle.agent.send([{
+    handle.agent.followup([{
       type: 'text',
       text: 'Use one run_code program to call tools.read on pkg/deep/task.txt. After it finishes, answer: Code Mode workspace handshake?',
     }])