[BUG] Cloud routine (CCR) stuck at "Claude Code process started" — never executes

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

On-demand "run now" triggers of a scheduled cloud routine (created via the /v1/code/triggers API, aka claude.ai routines) reliably provision a sandbox, log Claude Code process started, and then hang forever. No further log lines, no tool calls, no completion, no error. Reproduced 5/5 times across different configurations, ruling out anything in the routine's own config.

What Should Happen?

On-demand "run now" triggers of a scheduled cloud routine (created via the /v1/code/triggers API, aka claude.ai routines) reliably provision a sandbox, log Claude Code process started, and then hang forever. No further log lines, no tool calls, no completion, no error. Reproduced 5/5 times across different configurations, ruling out anything in the routine's own config.

Error Messages/Logs

Every attempt produces exactly this log, then stops:

env[info]: Allocating sandbox
env[info]: Environment runner started
env[info]: Initializing environment
env[info]: No sources configured
env[info]: No setup script configured
env[info]: Parallel initialization completed
env[info]: Claude Code executor created
env[info]: Starting Claude Code
env[info]: Claude Code process started

Steps to Reproduce

Create a routine via POST /v1/code/triggers with job_config.ccr pointing at either available environment_id (env_01D3UrT2t3H8nKj5SS6r6XuD or env_013ebLpX1V4LWogeoDi7wiRA).
Trigger it via POST /v1/code/triggers/{id}/run, or click "Run" in the claude.ai routines UI.
Poll GET /v1/code/sessions/{session_id}/events.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Code version 2.1.68.

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_