artgraph-verify

## Purpose The agent runs `artgraph check --diff` to self-check spec/impl/test consistency before code review or the Stop hook. Catching drift, orphans, and uncovered requirements early reduces rework cost. ## Steps ### 1. Prerequisite check See [install-check](../_shared/install-check.md) for the standard pre-flight check. If artgraph is not installed, stop and invoke the `artgraph-setup` Skill instead. > `<PM-exec>` is the project's package runner: `npx` (npm), `pnpm exec`, `bunx`, or `deno run -A npm:artgraph/cli`. Substitute the one detected by `_shared/package-manager.md` (or written in `.artgraph.json#packageManager`). ### 2. Run the consistency check ```bash <PM-exec> check --diff --format json ``` - `--diff` scopes the check to files changed by git diff. - Do NOT add `--gate` — that exits 2 on issues, which is for hook use only. We want the result for inspection. - **CI form** (spec 023): a CI pipeline gating a pull request runs `check --diff --base origin/<base-branch> --gate` instead — the working tree is clean in CI, so `--base <ref>` extends the diff with the committed `merge-base(<ref>, HEAD)..HEAD` range and judges only what the PR introduced. `--base` requires `--diff` (usage error exit 1 otherwise) and needs the full history (`actions/checkout` with `fetch-depth: 0`). ### 3. Interpret the JSON output See [output schema](../_shared/output-schema.md) for the shape of `artgraph check`. The scoped arrays (`drifted`, `orphans`, `uncovered`, `coverage`, `t...