Add ClaudeCLI provider for subscription-based Claude access

[gleber]

Adds a new provider that connects to the SilverBullet server's built-in Claude Agent SDK bridge at /.claude. Uses the Anthropic Messages API wire format with SSE streaming, tool use, and extended thinking support. No API key required — authenticates via the user's Claude subscription.

See silverbulletmd/silverbullet#1958 which is a prerequisite. @zefhemel FYI

@justyns Is this something you would be interested in getting merged? For now this is a quick vibecoding experiment. But if this is something interesting for you, I am willing to go full length and get this up to your standards.

[gleber]

Zef declined - with good reasons - accepting the bridge into Silverbullet server. I'll rebuild it as a separate side-car server running next to Silverbullet server.

@justyns Let me know if the proposed changes to silverbullet-ai sound reasonable to you, or if I will have to maintain a fork.

[justyns]

hey @gleber , if the goal is to be able to use a claude subscription, I am interested in getting it merged.

I didn't fully look at either PR, but it looked like the idea was to use the claude agent sdk. Doesn't that still require an anthropic api key?

I was under the impression to use a claude subscription, you have to actually shell out to claude -p and use the json flags. More than happy to be wrong if that's not the case though!

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One thing that has been on my list to look at for a while is ACP. Zed uses claude code cli via ACP without getting in trouble, so in theory maybe we could add a new provider for ACP and not make it claude specific?