feat(dx): Relax kebab-case rule for markdown and impeccable artifacts

Allow fully UPPER_CASE markdown names (README.md, AGENTS.md, ...) but
not mixed case, replacing the per-file markdown allowlist with a generic
rule. Also ignore the generated .impeccable/ directory, whose critique
files use ISO-8601 timestamp prefixes (e.g. 2026-06-14T08-26-30Z__<slug>.md)
that can never be kebab-case.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: enko

packages/danger/src/rules/kebab-case-files.ts

@@ -7,6 +7,11 @@ import { isExemptFile, isIgnoredPath } from '../utils';
 // and names like 2fa-setup are valid kebab-case.
 const KEBAB_CASE_STEM = /^[a-z0-9]+(-[a-z0-9]+)*$/;
 
+// Markdown docs may use a fully UPPER_CASE name (e.g. README.md, AGENTS.md,
+// CODE_OF_CONDUCT.md) — but not mixed case (Readme.md still fails). Segments
+// are uppercase alphanumerics separated by single hyphens or underscores.
+const SCREAMING_CASE_STEM = /^[A-Z0-9]+([_-][A-Z0-9]+)*$/;
+
 // Migration files use a "<timestamp>_<name>" pattern — strip the prefix before checking
 const MIGRATION_PREFIX = /^\d+_/;
 
@@ -30,6 +35,10 @@ const kebabCaseFiles: DangerRule = () => {
     // Strip migration timestamp prefix (e.g. "1774799536929_fix-bug" -> "fix-bug")
     stem = stem.replace(MIGRATION_PREFIX, '');
 
+    // Markdown docs may instead be fully UPPER_CASE (README.md, AGENTS.md, ...).
+    const isMarkdown = basename.toLowerCase().endsWith('.md');
+    if (isMarkdown && SCREAMING_CASE_STEM.test(stem)) continue;
+
     if (!KEBAB_CASE_STEM.test(stem)) {
       const suggestion = toKebabCase(stem);
       fail(

packages/danger/src/utils.ts

@@ -1,19 +1,20 @@
 import * as path from 'path';
 
-export const EXEMPT_BASENAMES = new Set([
-  'README.md',
-  'LICENSE',
-  'Dockerfile',
-  'Makefile',
-  'AGENTS.md',
-  'CHANGELOG.md',
-  'CONTRIBUTING.md',
-  'SECURITY.md',
-  'CODEOWNERS',
-  'MEMORY.md',
-]);
-
-const IGNORED_DIRS = ['node_modules/', 'dist/', '.svelte-kit/', 'vendor/', 'build/'];
+// All-uppercase markdown docs (README.md, AGENTS.md, CHANGELOG.md, ...) are
+// allowed by the kebab-case rule's SCREAMING_CASE handling, so they don't need
+// listing here — only non-markdown exceptions belong below.
+export const EXEMPT_BASENAMES = new Set(['LICENSE', 'Dockerfile', 'Makefile', 'CODEOWNERS']);
+
+const IGNORED_DIRS = [
+  'node_modules/',
+  'dist/',
+  '.svelte-kit/',
+  'vendor/',
+  'build/',
+  // Generated impeccable-design artifacts (e.g. timestamped critique files
+  // like 2026-06-14T08-26-30Z__<slug>.md) are not hand-authored source.
+  '.impeccable/',
+];
 
 export function isExemptFile(filePath: string): boolean {
   const basename = path.basename(filePath);