Cloud session creation can attach repository-trust proof, behind tengu_violin_fingerboard

What

A cloud session is a Claude Code session that runs on Anthropic's servers. A device-bound one is tied to your device. When Claude Code creates one from a local checkout (a copy of a repository on your machine), it can now attach a repositories_trusted field together with trusted-device proof headers:

• This only happens when the tengu_violin_fingerboard flag is on and the checkout folder is trusted. The flag falls back to off when no value is set.
• If the folder is not trusted or there is no token, nothing extra is sent and the create goes ahead without the field.
• If the server refuses the field with an error, Claude Code logs it and repeats the create without the field.
• Refusals are sorted into reasons such as not_covered, untrusted_device and session_stale.
• Whether the field was sent, not sent, or refused and then retried is recorded.

Before, the create request carried only its usual details and the flag did not exist. For tengu_violin_fingerboard, the flag server returned on for this site's account and for an anonymous baseline check, but no reading has been taken under this release yet.

Why

This lets a cloud session carry proof that the repository it starts from is trusted on your device. Because a refused field leads to a retry without it, creating a cloud session should still work when the server does not accept the field.