feat(skill): seo-signal-validation SKILL.md measurement half (L1-L2)

custom-skills/35-seo-signal-validation/SKILL.md

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+---
+name: seo-signal-validation
+description: |
+  Validate whether a claimed SERP / Knowledge-Graph movement for a (term, entity)
+  is real, misattributed, an artifact, or unprovable — before reporting impact.
+  Triggers: validate serp signal, is this ranking real, prove SEO impact,
+  SEMrush surge real, signal validation, real impact check,
+  신호 검증, 순위 변화 진짜, 오가닉 급증 검증, 임팩트 검증.
+---
+
+# SEO Signal Validation
+
+## Purpose
+
+Given a `(term/intent, entity)` pair — and optionally a **claim** (a third-party
+tool's reported movement) or a **baseline** (a prior state) — return an
+evidence-backed verdict on whether SERP and Knowledge-Graph impact is real.
+Built because modeled third-party signals (SEMrush/Ahrefs estimated organic
+traffic, position snapshots) are easy to over-trust. This skill makes the
+measured → live → entity → attribution cascade a single repeatable procedure
+ending in a defensible verdict and a client-safe narrative.
+
+## When to use (boundary)
+
+This is the **conductor**, not an instrument. It sequences and synthesizes the
+three measurement skills — it does not duplicate them.
+
+| Use instead | When |
+|---|---|
+| `20-seo-serp-analysis` | You only need SERP composition / features |
+| `21-seo-position-tracking` | You only need rank over time |
+| `28-seo-knowledge-graph` | You only need an entity-presence audit |
+| **this skill** | You must adjudicate whether a *claimed movement* is real across layers |
+
+## Step 0 — Classify entity + pick mode
+
+1. **Entity ownership** (gates which layers exist):
+   - **First-party** — a site/property you own or have GSC/GA4 access to (e.g. JHR
+     `sc-domain:josunhotel.com`, GA4 `258308769`) → **L1 measured available**.
+   - **Third-party** — a competitor brand or a person you do not control →
+     **L1 unavailable**; lean on L2 + L3 + clearly-tiered estimates; apply the
+     confidence cap (see Verdict). If unclear, ask once.
+2. **Mode** (thin wrappers over the same cascade):
+   - `adjudicate(claim)` — a 3rd-party tool reports a move; confirm/refute.
+   - `prove(baseline)` — after our change; before/after from GSC/GA4 history.
+   - `snapshot()` — no claim; "where do we really stand."
+
+## The validation loop (cost-ordered cascade, short-circuiting)
+
+Run cheapest-first; stop early when a layer is already decisive.
+
+### L1 — Measured (first-party ground truth) → via `21-seo-position-tracking`
+
+- **GSC** `mcp__dda__gsc_fetch_performance`: the term at **query level** (exact)
+  AND **site-wide**, for **recent vs prior** windows. Pull clicks / impressions /
+  position / CTR. **Day-normalize** (compare windows differ in calendar-day count).
+  Note **~43% query-level anonymization** — the disclosed subset ≠ the whole.
+- **GA4** `mcp__dda__ga4_run_report`: `Organic Search` sessions monthly trend
+  (dims `yearMonth` + `sessionDefaultChannelGroup`, metric `sessions`). GA4
+  includes Naver + all engines — use it to test whether a "surge" exceeds normal
+  month-to-month variance.
+- **Compute deltas with the helper** (deterministic, avoids ad-hoc parsing):
+  save each GSC pull, then run
+  `python3 code/scripts/gsc_signal_delta.py --recent <recent.tsv> --prior <prior.tsv> --recent-days N --prior-days M --claim-term "<term>"`.
+  It returns day-normalized site totals, top gainers/decliners, and whether the
+  claimed term is among the real movers.
+- **SHORT-CIRCUIT:** if the claimed keyword has trivial clicks and a real
+  position nowhere near the claim → **ARTIFACT**; stop unless the caller wants
+  the full picture.
+
+### L2 — Live SERP (3rd-party measured, point-in-time) → via `20-seo-serp-analysis`
+
+- **Geo-correct Google render** via `claude-in-chrome` (`navigate` → `read_page`):
+  force `gl`/`hl` + correct geo, `pws=0`; **decline precise-location prompts**.
+  Confirm whether the domain actually holds the claimed position; capture the
+  feature landscape (ads, local map-pack, PAA, knowledge panel) that explains why
+  a brand site can't own a head term.
+- **Cheap rank spot-check**: `mcp__ourseo__check_serp(keyword, domain)`.
+- **[KR market]** Naver SERP composition: `our research naver serp` (blog / cafe /
+  지식iN / Smart Store / brand zone) — Semrush/Ahrefs don't model Naver.