Claude.ai onboarding loop when redirecting to /code from Slack integration

Bug Description

When using the Claude Slack app and clicking the link to set up an environment at claude.ai/code, the browser gets stuck in an onboarding redirect loop (claude.ai/onboarding?returnTo=%2Fcode). The onboarding screen ("Is Sadia how I should refer to you?") keeps appearing repeatedly despite already having a Claude Code subscription and being fully signed in.

Steps to Reproduce

1. Use @Claude in a Slack channel to request a task (e.g., creating a Linear card)
2. Claude Slack bot responds: "No environments detected. This likely means your account has no environments set up. Please create a new environment at claude.ai/code."
3. Click the claude.ai/code link
4. Browser redirects to claude.ai/onboarding?returnTo=%2Fcode
5. Onboarding screen appears asking to confirm name
6. After submitting, it loops back to the same onboarding screen instead of proceeding to /code

Expected Behavior

Should redirect to claude.ai/code and allow environment setup, not loop on onboarding.

Environment

• Claude Plan: Active Claude Code subscription
• Slack: Claude app installed and authenticated ("Authentication successful!" message received)
• Browser: Chrome