Copilot/claude fable 5

[j4ys0n]

Summary

Adds claude-opus-4-8 and claude-fable-5 to the Anthropic baseline catalog, and updates latest-model metadata so only Opus 4.8 is treated as the latest Anthropic default. This keeps Fable 5 selectable without changing default resolution away from Opus.

Changes

• Anthropic catalog

  • Added baseline entries for claude-opus-4-8 and claude-fable-5
  • Updated the opus alias to resolve to claude-opus-4-8
  • Kept fable as a supported alias for claude-fable-5
  • Removed latest: true from Fable 5 so only Opus 4.8 remains marked latest

• Agent option coverage

  • Updated shared agent-option tests to reflect the new Opus default
  • Added coverage for the fable alias and the expanded Anthropic family grouping

{
  id: "claude-opus-4-8",
  family: "opus",
  latest: true,
}

{
  id: "claude-fable-5",
  family: "fable",
}

Testing

• Tests pass (pnpm turbo test)
• Typechecks pass (pnpm turbo typecheck)

Related

Issue: #540

Screenshots