feat(health): canonical artifact registry and W019 unrecognized-file lint (#2448) (#2488)

Adds artifacts.cjs with canonical .planning/ root file names, W019 warning
in gsd-health that flags unrecognized .md files at the .planning/ root, and
templates/README.md as the authoritative artifact index for agents and humans.

Closes #2448

get-shit-done/bin/lib/artifacts.cjs

@@ -0,0 +1,52 @@
+/**
+ * Canonical GSD artifact registry.
+ *
+ * Enumerates the file names that gsd workflows officially produce at the
+ * .planning/ root level. Used by gsd-health (W019) to flag unrecognized files
+ * so stale or misnamed artifacts don't silently mislead agents or reviewers.
+ *
+ * Add entries here whenever a new workflow produces a .planning/ root file.
+ */
+
+'use strict';
+
+// Exact-match canonical file names at .planning/ root
+const CANONICAL_EXACT = new Set([
+  'PROJECT.md',
+  'ROADMAP.md',
+  'STATE.md',
+  'REQUIREMENTS.md',
+  'MILESTONES.md',
+  'BACKLOG.md',
+  'LEARNINGS.md',
+  'THREADS.md',
+  'config.json',
+  'CLAUDE.md',
+]);
+
+// Pattern-match canonical file names (regex tests on the basename)
+// Each pattern includes the name of the workflow that produces it as a comment.
+const CANONICAL_PATTERNS = [
+  /^v\d+\.\d+(?:\.\d+)?-MILESTONE-AUDIT\.md$/i,  // gsd-complete-milestone (pre-archive)
+  /^v\d+\.\d+(?:\.\d+)?-.*\.md$/i,               // other version-stamped planning docs
+];
+
+/**
+ * Return true if `filename` (basename only, no path) matches a canonical
+ * .planning/ root artifact — either an exact name or a known pattern.
+ *
+ * @param {string} filename - Basename of the file (e.g. "STATE.md")
+ */
+function isCanonicalPlanningFile(filename) {
+  if (CANONICAL_EXACT.has(filename)) return true;
+  for (const pattern of CANONICAL_PATTERNS) {
+    if (pattern.test(filename)) return true;
+  }
+  return false;
+}
+
+module.exports = {
+  CANONICAL_EXACT,
+  CANONICAL_PATTERNS,
+  isCanonicalPlanningFile,
+};

get-shit-done/bin/lib/verify.cjs

@@ -903,6 +903,22 @@ function cmdValidateHealth(cwd, options, raw) {
     }
   } catch { /* intentionally empty — milestone sync check is advisory */ }
 
+  // ─── Check 13: Unrecognized .planning/ root files (W019) ──────────────────
+  try {
+    const { isCanonicalPlanningFile } = require('./artifacts.cjs');
+    const entries = fs.readdirSync(planBase, { withFileTypes: true });
+    for (const entry of entries) {
+      if (!entry.isFile()) continue;
+      if (!entry.name.endsWith('.md')) continue;
+      if (!isCanonicalPlanningFile(entry.name)) {
+        addIssue('warning', 'W019',
+          `Unrecognized .planning/ file: ${entry.name} — not a canonical GSD artifact`,
+          'Move to .planning/milestones/ archive subdir or delete if stale. See templates/README.md for the canonical artifact list.',
+          false);
+      }
+    }
+  } catch { /* artifact check is advisory — skip on error */ }
+
   // ─── Perform repairs if requested ─────────────────────────────────────────
   const repairActions = [];
   if (options.repair && repairs.length > 0) {