Fable Mode — Haiku (v3, agent-routed)

v3 change: the worker is a real agent definition (agents/fable-worker-haiku.md)
invoked by name. Its system prompt carries the loop, the tightened verification
rule, and the operational rules; this skill only routes.

If a task has one obvious correct approach and fits in a single pass, skip this
loop and do it directly.

How to run it

1. Confirm fable-worker-haiku appears in the available agent types. If not,
   fall back to inline: spawn a general-purpose Haiku agent and pass it the
   rules verbatim from agents/fable-worker-haiku.md.
2. Spawn @fable-worker-haiku via the Task tool (subagent_type: "fable-worker-haiku"). Brief it with: the task, the exact output path(s),
   and the pass condition — name the check explicitly; Haiku gets no benefit of
   the doubt on verification.
3. Haiku is cheap: for independent sub-parts, fan out one worker per part and
   merge. Set a ceiling on concurrent workers.
4. Follow with @fable-verifier (a second Haiku is cheap; fresh eyes can't
   inherit the worker's blind spots) for anything that will be delivered
   without human review.
5. If a worker escalates ("needs synthesis"), re-route that part to
   fable-worker-sonnet rather than retrying Haiku with a louder prompt.