docs-impact-classifier

# docs-impact-classifier Single responsibility: given a PR diff and the `.apm/docs-index.yml` corpus map, emit ONE classification verdict. This skill is the cost gate for the entire docs-sync system. ~70% of PRs should exit at verdict `no_change` with zero panel spawn. ## Architecture This is a 3-layer funnel inside a single skill invocation: - **L0 deterministic path gate** -- pure file-path matching, no LLM. - **L1 symbol extraction + corpus grep** -- pure text processing, no LLM. - **L2 LLM classifier** -- bounded ~8 KB context envelope, 1 call. The skill returns the verdict from the earliest layer that can decide. ## Step 1: L0 deterministic path gate (no LLM) Read `.apm/docs-index.yml` to load `no_impact_paths[]` and `user_surface_paths[]`. Get the changed file list from the PR diff (`gh pr diff --name-only`). ``` if every changed file matches no_impact_paths AND none match user_surface_paths: return {verdict: "no_change", confidence: "high", source: "L0", scope_pages: []} ``` This handles: - Test-only PRs (`tests/**`) - CI workflow PRs (`.github/workflows/**`) - Doc-only PRs (`docs/**`) -- out of scope, docs-sync doesn't review docs PRs - Primitive-only PRs (`.apm/**`) - Script and meta PRs Expected hit rate: ~70% of PRs short-circuit here. ## Step 2: L1 symbol extraction + corpus grep (no LLM) If L0 did not exit, extract user-observable symbols from the diff: - **CLI command names** -- grep diff for `^@click.command`, `^@cli.command`, or any `apm <ver...