1.74.11

• faa10c5: Add support for Claude Fable 5 (claude-fable-5) and its un-classified sibling Claude Mythos 5 (claude-mythos-5) as selectable models for --tool claude (Issue #1875). New aliases fable, fable-5, claude-fable-5, mythos-5, and claude-mythos-5 resolve in the centralized model registry, support the [1m] 1M-context suffix, the full effort ladder including xhigh and max (default high), and 128K max output tokens. Both models are adaptive-thinking-only, so getClaudeEnv removes MAX_THINKING_TOKENS for them (the API rejects disabled thinking), mirroring Opus 4.7/4.8. Documented default fallbacks are registered (claude-fable-5 -> opus reflecting Fable 5's safety-classifier hand-off to Opus 4.8; claude-mythos-5 -> fable). Existing defaults (opus, sonnet, haiku, opusplan) are unchanged — this adds Fable 5 as an option without altering current behavior. fable is surfaced in --model help. Includes tests/test-fable-5-model-support.mjs (127 tests) and a full case study under docs/case-studies/issue-1875/.

Related Pull Request: #1876

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