When unsure which thinking skill fits, map domain and problem type, then return NONE or one primary skill by default (at most three complementary).

Model Router Core rule: Prefer NONE or one primary skill. Route by mechanism fit, not habit. Combine only when roles are distinct and necessary. When to Use The right thinking skill is unclear and you would otherwise guess or stack tools. Several catalog skills seem plausible and you need a single primary (or explicit NONE). High stakes work where a wrong frame is costly and a quick domain×type match helps. When NOT to Use The match is already known or obvious ("where's the bottleneck?" → theory of constraints) — invoke that skill directly; do not route for show. The task is routine implementation with no analytical unknown — reason directly (NONE). You are mid execution of an agreed plan and only need the next concrete step. The ask is outside this catalog (pure coding syntax, tool ops with no judgment call) — NONE. Invoking a Model (Skill IDs) The router outputs bare slugs (e.g. id: five whys plus ). Invoke a routed skill with the Skill tool using the exact ID thinking skills:thinking <slug — never invent a slug not cited in Procedure. NONE means no invocation. Procedure 1. Short circuit. If one skill clearly fits by mechanism, return that skill alone. If no skill clearly improves the work, return NONE and reason directly. Stop. 2. Characterize. Record domain (coding, architecture, product, strategy, personal, abstract, risk, innovation) and problem type (diagnose, decide, understand, create, evaluate, predict, optimize). Note constraints: time, information, stakes, reversibility, complexity. 3. Candidate by type defaults (override when constraints demand). Keep only active catalog skills: Diagnose → five whys plus or scientific method (kepner tregoe if IS/IS NOT matrix needed) Decide → reversibility first; then opportunity cost or probabilistic Understand → systems (map territory if model vs reality gap; cynefin if approach domain unclear) Create → first principles (triz for contradictions; effectuation for means driven; via negativa for remove first) Evaluate → steel manning (socratic if assumptions/definitions are the unknown) Predict → probabilistic Optimize → theory of constraints (ooda under time pressure; bounded rationality for search stop) Risk / "what fails?" → pre mortem or red team; margin of safety for buffers Product "what to build?" → jobs to be done Competence / durability → circle of competence, lindy effect Controlled hypothetical → thought experiment Multi lens only after one primary fails a blind spot check → model combination 4. Select with criteria (satisficing). Score only if 2+ candidates remain or stakes make a forced default unsafe. Rate each criterion 1–5 (1 = absent/wrong fit; 3 = usable with gaps; 5 = direct fit): problem fit (30%), available inputs (20%), time to apply (15%), stakeholder usability (15%), competence to apply correctly (20%). A route must score problem fit ≥4 and weighted total ≥3.5; otherwise return NONE . For totals within 0.25, prefer fewer inputs and shorter execution; if still tied, choose NONE unless the skills answer distinct complementary questions. 5. Multi skill only as exception. Add a second or third skill only when each has a distinct complementary role the primary leaves open. Cap at three. Prefer sequential over parallel. Near neighbors and synonyms do not stack. For composition patterns, hand off to model combination after naming the primary. 6. Exit. State abandon signals (forced fit, ignored factors, no insight ~15 minutes). On mismatch, re route once or fall back to NONE — never force a frame. Domain cheat map (primary first; still default to one or NONE): Domain signal Prefer Bug / root cause / flaky five whys plus, scientific method, systems Architecture / tech choice reversibility, systems, lindy effect, opportunity cost Feature / roadmap / engagement jobs to be done, opportunity cost, theory of constraints Strategy / competition / growth cynefin, systems, red team, second order Personal / career commitment opportunity cost, reversibility, circle of competence, pre mortem Argument / belief update steel manning, probabilistic, socratic, first principles Security / disaster / ruin pre mortem, red team, margin of safety, via negativa Innovation / contradiction / simplify first principles, triz, effectuation, via negativa Output Default fill: outcome: NONE with one id: NONE route, or outcome: one with one route. Use multi only when every listed skill has a distinct role and unique question. Verification Falsify / stop: If the route is habit or familiarity rather than mechanism fit, discard and re score or return NONE. If multi skill entries lack distinct roles, collapse to the single best primary. If no candidate clearly helps, NONE is correct — do not invent a route. Over application guard: Do not route when the skill is already obvious. Do not return more than three skills. Do not cite deleted or non catalog names. Do not treat the router as a prerequisite for leaf skills invoked directly.

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