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.