fix: add /remote-control-diagnose command to help users debug RC feature flag issues

[HarshalJain-cs]

Summary

This PR adds a new slash command .claude/commands/remote-control-diagnose.md to help users diagnose and resolve the widespread Remote Control environments are not available for your account. error reported in #29449 and related issues (#28816, #28817, #28884, #29037, #29164, #29185, #29430).

Problem

Over 22 users have upvoted issue #29449 reporting that claude remote-control returns one of several variants of this error even for valid Pro/Max plan users:

• Remote Control environments are not available for your account. (v2.1.62)
• Remote Control is not yet enabled for your account. (v2.1.69)
• Remote Control is not enabled. Wait for the feature flag rollout. (v2.1.70)

The underlying cause is a server-side feature flag (tengu_ccr_bridge) that must be enabled per account. Additionally, using CLAUDE_CODE_OAUTH_TOKEN in .env files can cause RC to fail even on otherwise eligible accounts.

Solution

Adds .claude/commands/remote-control-diagnose.md — a slash command that:

1. Gathers relevant user context (version, plan, auth status, platform)
2. Triages the specific error message to its root cause
3. Walks the user through all known workarounds in priority order
4. Composes an empathetic, actionable reply pointing to the rollout tracking issue

Testing

• File follows existing .claude/commands/ format (YAML frontmatter + markdown body)
• Covers all known error message variants as of v2.1.70
• Includes the CLAUDE_CODE_OAUTH_TOKEN edge case discovered in [BUG] "Remote Control environments are not available for your account." for Claude Code Pro Plan user #29449 discussion
• Links to tracking issue [Bug] Remote Control unavailable despite Pro plan authentication #28817 for rollout progress

Related Issues

Closes #29449
Related: #28816, #28817, #28884, #29037, #29164, #29185, #29430, #29980, #30756, #30820

[bliednov]

This is a nice step-by-step.
Because I finally found what was the cause.
CLAUDE_CODE_OAUTH_TOKEN was the cause.
I have max plan btw.