Fable 5.1 fails because Claude Code is reported as version 2.1.75

[ephraimduncan]

Description

Fable 5.1 cannot be used through Prime Agent because the provider request identifies Claude Code as version 2.1.75. The model requires Claude Code 2.1.251 or newer.

Steps to reproduce

1. Run Prime Agent.
2. Select Fable 5.1.
3. Send a message.

Expected behavior

Fable 5.1 handles the request normally.

Actual behavior

The request is rejected with:

Provider rejected the request (invalid_request_error, 400): Claude Code 2.1.75 does not support this model; version 2.1.251 or newer is required. Run 'claude update', or update the Claude desktop app, then try again.

Prime Agent retries once and receives the same error.

Prime Agent version

0.9.1

Operating system

macOS

Additional context

The system-installed Claude Code is already current:

$ claude --version
2.1.257 (Claude Code)

This suggests the Claude Code provider integration in Prime Agent is reporting or bundling version 2.1.75 independently of the installed CLI.

[maxkunisch]

Same failure here on 0.9.1 / macOS 26 / Node 24.15, with claude-fable-5-1 (also claude-fable-5). Opus 5 works with the same login.

The fix is a one-line bump. The Anthropic provider has:

claudeCodeVersion = "2.1.75"

Bumping it to "2.1.257" (current Claude Code release) resolves the error. Both the bundled dist/bundle/anthropic-*.js and @earendil-works/pi-ai/dist/providers/anthropic.js carry the constant.

It would also help to make this a config or env override so users aren't blocked until a new release each time the minimum moves.

[snimu]

Addressed by #1993