Fable Mode — Opus (v6, main-thread orchestration)

Family version: v6 (2026-10-10).

v4 removed the named-agent routing from v3. That design depended on custom agent definitions (fable-orchestrator, fable-worker-sonnet, fable-worker-haiku, fable-verifier) that do not exist on skill-only surfaces like Cowork — so every invocation fell through to the fallback while the file still described the dead path as primary, and the v3 structural guarantee never actually applied. The fallback is now the only path, stated directly.

v5 change: this skill is now the top of the ladder. The Fable 5.1 runner was removed from the skill set (its own benchmark measured zero correctness delta at that tier), so escalation past Opus goes to the user, not to another runner.