End-to-end workflow that describes the way Fable ran sessions - parallel evidence subagents when the host supports them, one committed plan, surgical execution with an intent gate, adversarial verification, honest outcome-first report. Use for non-trivial multi-step tasks when the user says "/fable-loop", "run the fable loop", or "do this the way Fable would". For the rules alone without orchestration, use fable-method; for the plain task cycle without subagents, use task-cycle; for large multi-phase projects, prefer the GSD workflow and use this inside phases.
Install
npx skillscat add youlianvr/oper-share/fable-loop Install via the SkillsCat registry.
The Fable Loop
This skill describes an orchestration workflow around fable-method: read its SKILL.md first; its rules govern every stage. The method says WHAT to check; this loop describes WHO may do the work when the host exposes subagent support. In hosts without that capability, run the same evidence and adversarial checks inline; do not claim that subagents were spawned.
Gate first. Trivial per the method's triviality gate: just do it, verify with the one obvious check, report in two sentences. No stages, no subagents. Everything else runs the four stages below in order.
Stage 1 - PLAN (the first bookend)
- Apply method Steps 0-3: classify the ask, define done with a named verification, state load-bearing assumptions.
- Evidence fan-out. If the host exposes a verified subagent facility, spawn evidence gatherers as parallel subagents in ONE message, never sequentially. Otherwise perform the same independent lookups inline/batched and record the fallback; never imply a spawn occurred:
- codebase questions: an Explore agent per distinct area ("how does X work", "what depends on Y");
- library or fact questions: a research agent that fetches current docs or searches the web;
- each subagent returns distilled findings with citations, never raw file dumps.
One batch plus one follow-up batch is the budget; a third needs a stated reason.
- Produce the plan artifact in this shape: classification; definition of done plus its verification; evidence found (cited); ONE recommended approach (alternatives dismissed in a line each); the scope (the exact files or surfaces the work will touch); risks and assumptions; and the execution checklist.
- Decision gate. Task-shaped and reversible: proceed to Stage 2 without asking. Plan-first shape (ambiguous scope, irreversible or outward-facing actions, or the user asked for a plan): present the plan artifact and STOP for approval.
Stage 2 - EXECUTE
- Work the checklist in the main thread (use the todo tool if the harness has one; tick items as they complete). Deciding and editing stay in the main thread; only searching and verifying fan out.
- Every edit follows method Step 4: intent gate before behavior changes, recall gate before first use of anything unopened, smallest correct change, precise edits, never destroy without looking.
- Independent mechanical items (same change across many files, isolated file generation) may fan out to parallel subagents, in one message, with worktree isolation if they could touch the same files.
- A surprise mid-execution re-routes per method Step 2 rule 7: say it, then update the plan or go back to Stage 1. Never force the plan through a surprise.
- Mid-item ignorance is a pause, not a guess: the moment an edit would carry a fact from memory (a signature, a key, a figure), stop that item, fan out one research subagent per the method's recall gate, and resume when it returns.
- Outward-facing checklist items obey the method's authorization gate: no quoted user authorization, no action; the item converts to a proposed next step in the report.
Stage 3 - VERIFY (adversarially)
- Run the named verification yourself, both halves: the done criterion observed (ran, rendered, counted), and the surrounding system still healthy (build, tests, lint for the touched area).
- For consequential changes, use adversarial checks. If verified subagent support exists, spawn 1-3 parallel attackers; otherwise run distinct refutation checks inline. Example prompts/lenses: "Read this diff and prove the change is wrong or incomplete", "Exercise the changed behavior at runtime and find an input that breaks it", "Check this claim against the spec/docs and find a contradiction", "Diff the full change set against the plan's declared scope and prove something outside it changed". Distinct lenses beat identical reviewers.
- A finding that survives your own check goes back to Stage 2 as new work. Hard bound per the method: 3 failed fix-verify cycles on the same issue, or any blocker outside your control, means stop and hand back with the output and your hypothesis.
Stage 4 - AUDIT and REPORT (the second bookend)
- Self-audit per fable-method audit mode: for each method step, followed, skipped, or faked. Fix what one pass can fix (usually an unverified claim: verify it now or relabel it a caveat).
- Deliver per method Step 6: outcome in the first sentence, verification evidence shown, honest caveats, follow-ups only if they emerged from the work. No stage names or step numbers in the report; the INTENT and AUTH lines are the only method artifacts a report may contain.
When NOT to use this loop
- Trivial tasks (the gate handles them).
- Pure questions with no multi-step work: plain fable-method covers the shape.
- Inside an already-orchestrated GSD phase: GSD owns the stages there; apply fable-method rules within them instead of nesting loops.
Model economy
The loop is model-agnostic. Evidence and attacker subagents are cheap-model-friendly; keep the main thread (deciding, editing) on the strongest model available, and give attackers higher effort than gatherers when a choice exists.