feat(checks): unify inspection scope in checks/scope.ts

Single source of truth for what pygienium inspects (implementation-code
extensions, exclude dirs, .d.ts/.min.* exclusions) shared by recon,
dead-code, deep-modules, defensive-guards, comments, and complexity.
Every scan task and agent prompt injects the shared scope rules instead
of copy-pasted per-check lists.

src/checks/dead-code.ts

@@ -34,6 +34,11 @@ import {
 	type CheckDefinition,
 	type CheckScope,
 } from "./registry.js";
+import {
+	isScopeSource,
+	SCOPE_EXCLUDE_DIRS,
+	scopeRulesMarkdown,
+} from "./scope.js";
 
 /** Dead-code categories recognised by the rubric. */
 export type DeadCategory = "export" | "file" | "shim" | "dep";
@@ -82,43 +87,6 @@ export const CATEGORY_LABELS: Record<DeadCategory, string> = {
 	dep: "Unused dependencies",
 };
 
-/** Source extensions worth scanning for import graphs. */
-const SOURCE_EXTENSIONS = new Set([
-	".ts",
-	".tsx",
-	".js",
-	".jsx",
-	".mjs",
-	".cjs",
-	".py",
-	".rb",
-	".go",
-	".rs",
-	".java",
-	".kt",
-	".swift",
-	".php",
-	".cs",
-	".lua",
-]);
-
-/** Directories never scanned (build output, deps, tooling). */
-const IGNORED_DIRS = new Set([
-	"node_modules",
-	".git",
-	".pygienium",
-	"dist",
-	"build",
-	"out",
-	"coverage",
-	".next",
-	".nuxt",
-	".venv",
-	"__pycache__",
-	"vendor",
-	".ralpi",
-]);
-
 /** Extensions tried when resolving a bare import specifier. */
 const RESOLVE_EXTENSIONS = [
 	".ts",
@@ -131,11 +99,6 @@ const RESOLVE_EXTENSIONS = [
 	".cts",
 ];
 
-const EXT = (name: string): string => {
-	const i = name.lastIndexOf(".");
-	return i === -1 ? "" : name.slice(i).toLowerCase();
-};
-
 /** Filename signals of a compat/deprecated/migration shim. */
 const SHIM_NAME_RE =
 	/(?:compat|legacy|deprecated|obsolete|obsoleted|migration|migrate|backcompat|back-compat|fallback|shim)/i;
@@ -161,7 +124,7 @@ function depStem(spec: string): string {
 async function walkSourceFiles(root: string): Promise<string[]> {
 	const st = await stat(root).catch(() => undefined);
 	if (!st) return [];
-	if (st.isFile()) return SOURCE_EXTENSIONS.has(EXT(root)) ? [root] : [];
+	if (st.isFile()) return isScopeSource(root) ? [root] : [];
 	const out: string[] = [];
 	const stack = [root];
 	while (stack.length > 0) {
@@ -175,9 +138,9 @@ async function walkSourceFiles(root: string): Promise<string[]> {
 		for (const entry of entries) {
 			const full = join(dir, entry.name);
 			if (entry.isDirectory()) {
-				if (IGNORED_DIRS.has(entry.name)) continue;
+				if (SCOPE_EXCLUDE_DIRS.has(entry.name)) continue;
 				stack.push(full);
-			} else if (entry.isFile() && SOURCE_EXTENSIONS.has(EXT(entry.name))) {
+			} else if (entry.isFile() && isScopeSource(entry.name)) {
 				out.push(full);
 			}
 		}
@@ -1069,6 +1032,8 @@ export async function buildDeadCodeScanTask(
 		"```",
 		``,
 		`Target root: ${scope.target}. Work dir: ${cwd}.`,
+		``,
+		scopeRulesMarkdown(),
 	].join("\n");
 }