📝 docs: 补上提交信息规范的自查脚本

scripts/check-commit-log.mjs 按 CONTRIBUTING.md 的类型表检查提交首行，
只报告不拦提交。它从规范文件里读 emoji 对照，所以改表不用改脚本。

同时收紧规范：emoji 由「可选」改为「必需且必须与类型一致」。原先的写法
下 ✨ docs: 这类不匹配不会被发现。

CONTRIBUTING.md

@@ -12,7 +12,7 @@
 [脚注：Refs: #12 / Closes: #34 / BREAKING CHANGE: ...]
 ```
 
-- `<emoji>`：下面表格里该类型对应的 emoji，后面跟**一个空格**。
+- `<emoji>`：下面表格里该类型对应的 emoji，后面跟**一个空格**。emoji 是必需的，且必须与本行类型一致——`📝 docs:` 对，`✨ docs:` 不对。
 - `<type>`：小写英文关键字，见下表。
 - `(scope)`：可选，改动范围。用 `()` 包住一个简短英文标识，例如 `docs(ci)`、`fix(client)`、`feat(host)`。
 - `!`：可选，紧跟在 type 或 scope 之后、冒号之前，表示破坏性变更。
@@ -83,6 +83,17 @@ emoji 在行首是本仓库的有意选择，视觉上整齐。代价是：以
    ^(?:\p{Extended_Pictographic}\uFE0F?\s+)?(?<type>[a-z]+)(?:\((?<scope>[^)]*)\))?(?<breaking>!)?:\s(?<desc>.+)$
    ```
 
+## 自查
+
+`scripts/check-commit-log.mjs` 会按本规范检查现有提交的首行，只报告、不拦提交：
+
+```bash
+node scripts/check-commit-log.mjs        # 最近 10 条
+node scripts/check-commit-log.mjs all    # 全部
+```
+
+它从本文件的类型表里读 emoji 对照表，所以改了表不用改脚本。规范之前的提交不符合是正常的。
+
 ## 启用提交模板（可选）
 
 `.gitmessage` 是提交信息模板。启用后每次 `git commit` 会带上前缀提示，删掉不需要的部分即可：

scripts/check-commit-log.mjs

@@ -0,0 +1,74 @@
+// Checks real commit subjects (newest first) against the CONTRIBUTING.md spec:
+// the documented regex must parse them, the leading emoji must be present and
+// match the type table exactly, and the subject must stay within 72 width.
+//
+// This is a reporting tool, not a hook: it never blocks a commit.
+//
+// Usage:
+//   node scripts/check-commit-log.mjs          # newest 10 commits
+//   node scripts/check-commit-log.mjs 50       # newest 50 commits
+//   node scripts/check-commit-log.mjs all      # every commit
+//   DSD_SPEC=path/to/CONTRIBUTING.md node scripts/check-commit-log.mjs
+import { execFileSync } from 'node:child_process'
+import { readFileSync } from 'node:fs'
+import { dirname, resolve } from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+const repoRoot = resolve(dirname(fileURLToPath(import.meta.url)), '..')
+const specPath = process.env.DSD_SPEC ?? resolve(repoRoot, 'CONTRIBUTING.md')
+const doc = readFileSync(specPath, 'utf8')
+const count = process.argv[2] ?? '10'
+
+/** The regex the spec documents for stripping a leading emoji. */
+const SUBJECT = new RegExp(
+  '^(?:\\p{Extended_Pictographic}\\uFE0F?\\s+)?' +
+  '(?<type>[a-z]+)' +
+  '(?:\\((?<scope>[^)]*)\\))?' +
+  '(?<breaking>!)?' +
+  ':\\s(?<desc>.+)$',
+  'u',
+)
+
+// The spec's table is the single source of truth for the type → emoji mapping,
+// so a table edit cannot drift from what this script checks.
+const emojiOfType = new Map()
+for (const row of doc.split('\n').filter((line) => /^\| `[a-z]+` \| /.test(line))) {
+  const cells = row.split('|').map((cell) => cell.trim())
+  emojiOfType.set(cells[1].replaceAll('`', ''), cells[2])
+}
+if (emojiOfType.size === 0) throw new Error(`${specPath} has no type table to read`)
+
+/** Strip the variation selector, so '♻' and '♻️' compare equal. */
+const base = (text) => text.replace(/\uFE0F/g, '')
+/** Display width, counting anything above U+2000 as double. */
+const widthOf = (text) => [...text].reduce((n, c) => n + (c.codePointAt(0) > 0x2000 ? 2 : 1), 0)
+
+const args = count === 'all' ? ['log', '--format=%h%x09%s'] : ['log', `-${Number(count)}`, '--format=%h%x09%s']
+const rows = execFileSync('git', args, { encoding: 'utf8', cwd: repoRoot })
+  .trim().split('\n').filter((line) => line !== '')
+
+let problems = 0
+for (const row of rows) {
+  const [hash, subject] = row.split('\t')
+  const notes = []
+  const match = SUBJECT.exec(subject)
+  if (match === null) {
+    notes.push('缺少类型前缀，或整体格式不是 <emoji> <type>[(scope)][!]: <描述>')
+  } else {
+    const expected = emojiOfType.get(match.groups.type)
+    const lead = [...subject][0]
+    if (expected === undefined) notes.push(`类型不在规范表里：${match.groups.type}`)
+    else if (base(lead) !== base(expected)) notes.push(`类型 ${match.groups.type} 的 emoji 应为 ${expected}，实际是 ${lead}`)
+    const width = widthOf(subject)
+    if (width > 72) notes.push(`首行宽度 ${width}，超过 72`)
+    if (/[。.]$/.test(subject)) notes.push('首行结尾不应有句号')
+  }
+  if (notes.length > 0) problems += 1
+  const mark = notes.length === 0 ? 'ok  ' : 'FAIL'
+  console.log(`  ${mark} ${hash} ${notes.length === 0 ? '' : notes.join('；') + ' — '}${subject}`)
+}
+
+console.log(problems === 0
+  ? `\n检查了 ${rows.length} 条提交，全部符合规范`
+  : `\n检查了 ${rows.length} 条提交，其中 ${problems} 条不符合规范（规范文件：${specPath}）`)
+process.exit(problems === 0 ? 0 : 1)