fix(i18n): make translation contracts executable

scripts/verify-translation-prompt.ts

@@ -0,0 +1,57 @@
+/** Verify that the committed translation prompt renders and parses as documented. */
+
+import { readFileSync } from 'node:fs'
+import { join, resolve } from 'node:path'
+import {
+  documentedTranslationPromptPlaceholders,
+  parseTranslationResponse,
+  renderTranslationPrompt,
+  renderTranslationResponse,
+  TRANSLATION_PROMPT_PLACEHOLDERS,
+} from './translation-prompt.ts'
+
+const root = resolve(import.meta.dirname, '..')
+
+function read(path: string): string {
+  return readFileSync(join(root, path), 'utf8')
+}
+
+try {
+  const document = read('docs/i18n/translation-prompt.md')
+  const translationRules = read('docs/i18n/translation-rules.md')
+  const terminology = read('docs/i18n/terminology.md')
+  const documented = documentedTranslationPromptPlaceholders(document)
+  if (documented.join('\n') !== TRANSLATION_PROMPT_PLACEHOLDERS.join('\n')) {
+    throw new Error(`placeholder table must list exactly: ${TRANSLATION_PROMPT_PLACEHOLDERS.join(', ')}`)
+  }
+
+  const englishSource = renderTranslationPrompt(document, {
+    sourceLanguage: 'English',
+    sourceFilename: 'example.md',
+    translationRules,
+    terminology,
+  })
+  const chineseSource = renderTranslationPrompt(document, {
+    sourceLanguage: 'Chinese',
+    sourceFilename: 'example.zh.md',
+    translationRules,
+    terminology,
+  })
+  if (englishSource.includes('{{') || chineseSource.includes('{{')) throw new Error('rendered prompt contains an unresolved placeholder')
+  if (!englishSource.includes('[English](example.md) | 中文')) throw new Error('English-source render does not carry the Chinese switcher instruction')
+  if (!chineseSource.includes('English | [中文](example.zh.md)')) throw new Error('Chinese-source render does not carry the English switcher instruction')
+
+  const example = /```xml\n([\s\S]*?)\n```/.exec(englishSource)?.[1]
+  if (example === undefined) throw new Error('rendered prompt has no XML response example')
+  parseTranslationResponse(example)
+
+  const roundTrip = { translation: 'first ]]> pass', review: '- [None] No corrections.', final: 'final ]]> text' }
+  const parsed = parseTranslationResponse(renderTranslationResponse(roundTrip))
+  if (JSON.stringify(parsed) !== JSON.stringify(roundTrip)) throw new Error('CDATA split rule does not round-trip response content')
+
+  console.log('verify-translation-prompt: both directions render and the XML response contract parses.')
+} catch (error) {
+  const message = error instanceof Error ? error.message : String(error)
+  console.error(`verify-translation-prompt: ${message}`)
+  process.exit(1)
+}