DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.
The model picker used when configuring subagents (e.g. in the Workflow tool's agent options) now includes a Fable option alongside Sonnet, Opus, and Haiku. This allows subagents to be spawned on Fable 5 when available.
Evidence
Subagent model list (search for "Most capable for your hardest and longest-running tasks" in the subagent picker function)
Strings lifted out of the shipped bundle, so the claim above can be checked against them.