Research
Claude Code v2.1.257 Adds Claude Fable 5.1 as the Default Fable Model With 1M Context at $10/$50 per Mtok
Anthropic published claude-code v2.1.257 on 2026-09-01 at 17:53 UTC, adding claude-fable-5-1 as the new default Fable model with a 1M-token context window, $10 per Mtok input and $50 per Mtok output, and $0.25 per Mtok cache reads. The same release adds CLAUDE_CODE_SUBAGENT_MODEL_FORCE to apply a subagent model override to every subagent regardless of per-spawn or agent-definition settings, and a session-scoped 's' option in /effort. A follow-up v2.1.258 shipped the same day at 22:33 UTC fixing a macOS 12 launch regression introduced in 2.1.255.
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