| name | fable-engine |
| description | Turn a plain-English vision or task into a verified, build-ready spec before any code. Locks the finish line, researches across channels, enforces the Evidence Standard, stops at the human gate. Adopted from CleanExpo/Fabel-Prompt-Engineer for the Synthex build process. |
Fable Engine (Synthex build process)
Input: a vague idea or a non-trivial change in plain English. Output: a precise,
sourced, build-ready spec. You propose; the human decides. Pairs with
.claude/rules/fabel-evidence-standard.md and .claude/FABEL_PLAYBOOK.md.
Use it for: a new feature, a workstream/elevation wave, a risky refactor, or any
multi-agent fan-out. Skip it for: a one-line fix or a conversational answer
(Fabel directive 1 — act when you have enough info).
Operating loop
1. Lock the finish line
Restate the task as one testable sentence: "Done when ___." If several finish
lines are plausible, pick the most likely, state it, list the rejected ones.
Emit: [STATUS] finish-line: locked — <one sentence>
2. Research channels (emit started/done per channel)
- Source channel — read the actual Synthex code +
.claude/ rules that
constrain or accelerate the change. Docs are stale; the source is truth.
- Prior-work channel — search merged PRs,
.claude/scratchpad, memories,
and open PRs for decisions and existing patterns (e.g. defineRoute,
getEffectiveOrganizationId, the deploy-pipeline gotchas).
- Web channel — for external facts (API shapes, prices, library versions)
use Context7 / web; every web finding carries its source URL. No web access →
mark skipped, downgrade affected claims to
[UNCONFIRMED].
3. Filter through the Evidence Standard
Every finding and spec claim is tagged [VERIFIED] / [INFERENCE] /
[UNCONFIRMED] per fabel-evidence-standard.md. An untagged claim is a defect.
4. Synthesize, ask only what you can't infer
Draft the spec. Infer-and-tag rather than ask. Where info is genuinely missing,
list ≤5 concrete, answerable questions.
5. Board critique (high-stakes or on request)
Run boardroom / ask-the-board on the draft; append the combined critique as
a lens. Label it [INFERENCE] — persona synthesis, not fact. It feeds the gate,
never bypasses it.
6. Approval gate
Present the spec and stop. Nothing builds until the human approves. For the
agent fleet: the spec is the contract each subagent is dispatched against, and
the prod-deploy gate remains the founder's call.
Emit: [STATUS] gate: awaiting approval
Spec output format
- Finish line — the locked "done when" sentence.
- Decision up front — recommended path in one paragraph.
- Goals & non-goals — non-goals required.
- Approach — plain language first.
- Phased plan — smallest phase first; each phase has a definition of done;
no later phase before the earlier DoD is met. For a fleet wave: the disjoint
agent lanes + their file boundaries.
- Data model — if it stores anything (respect the Synthex migration rules:
apply_migration only, never prisma db push).
- Security & cost guardrails — secrets, org-scoping, spend; structural not
advisory.
- Risk & assumption register — every
[UNCONFIRMED] lands here.
- Open questions — the ≤5 from step 4, if any.
- Verification plan — the exact commands that will prove "done"
(
build:vercel, npm test -- --coverage, the integration gauntlet). Per
Fabel directive 5, a claim isn't done until its tool result says so.
Status grammar
[STATUS] <subject>: <state>[ — detail] — subjects: finish-line,
channel:source, channel:prior-work, channel:web, synthesis, board,
gate.
