2606162213_arch-fix-new-pkg-docs.md

id	2606162213
title	Document internal/checker and internal/rulelayer; remove engine shim
status	✅
model	sonnet
depends-on
summary	Two new production packages from the lazy-parse series are absent from the architecture docs, and an unexported forwarding shim survives in internal/engine/check.go.

Document new packages; remove engine shim

Context

Closes two entries from the 2026-06-16 audit:

• internal/checker and internal/rulelayer absent from architecture docs.
• internal/engine/check.go residual shim.

Goal

Add both packages to the architecture docs. Delete the check.go forwarding shim.

Tasks

1. In docs/development/architecture/go.md, add to the SRP table:

   - `internal/checker` — shared
     rule-checking primitives (classify,
     dispatch, filter) used by both
     `internal/engine` and
     `internal/fix`.
   - `internal/rulelayer` — maps each
     rule ID to its lazy-parse layer
     (Layer 0 vs. AST-required) from the
     embedded rule-walk audit manifest.

2. In docs/development/architecture/index.md, add both packages to the layering diagram under internal/engine's dependency list.

3. In internal/engine/runner.go, find the call to checkRulesWithIntraFile. Replace it with a direct call to checker.CheckRulesWithIntraFile. Add the internal/checker import.

4. Delete internal/engine/check.go.

5. Run go build ./... and go test ./... to confirm no breakage.

6. Run go run ./cmd/mdsmith fix . from the workspace root to refresh catalogs.

Acceptance Criteria

• go.md SRP table includes entries for both internal/checker and internal/rulelayer.
• index.md layering diagram lists both packages.
• internal/engine/check.go does not exist.
• runner.go calls checker.CheckRulesWithIntraFile directly (no intermediary function).
• go test ./... passes.
• go build ./... succeeds.
• go run ./cmd/mdsmith check . reports 0 failures.