ci: reverse-translate English replies into the OP language

.github/workflows/translate.yml

@@ -36,3 +36,152 @@ jobs:
         with:
           IS_MODIFY_TITLE: true
           APPEND_TRANSLATION: true
+
+  # English maintainer replies → OP language. Same unofficial Google endpoint as lizheming.
+  reverse:
+    if: >
+      github.actor != 'github-actions[bot]' &&
+      contains(fromJSON('["issue_comment","discussion_comment","pull_request_review_comment"]'), github.event_name)
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    steps:
+      - name: Reverse-translate English comment
+        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7
+        with:
+          script: |
+            const DIV = '<!--This is a translation content dividing line, the content below is generated by machine, please do not modify the content below-->';
+            const TITLE_DIV = ' || ';
+            const MAX = 4500;
+
+            const isEn = (code) => !code || /^en\b/i.test(String(code));
+            const origin = (text) => String(text || '').split(DIV)[0].trim();
+            const originTitle = (text) => String(text || '').split(TITLE_DIV)[0].trim();
+
+            async function gtx(text, sl, tl) {
+              const q = text.length > MAX ? text.slice(0, MAX) : text;
+              const params = new URLSearchParams({ client: 'gtx', sl, tl, dt: 't', dj: '1', q });
+              const res = await fetch(`https://translate.googleapis.com/translate_a/single?${params}`, {
+                headers: { 'User-Agent': 'Mozilla/5.0 NVM-Windows-Translate' }
+              });
+              if (!res.ok) {
+                throw new Error(`gtx HTTP ${res.status}`);
+              }
+              const data = await res.json();
+              let translated = '';
+              let src = '';
+              if (data && Array.isArray(data.sentences)) {
+                translated = data.sentences.map((s) => s.trans || '').join('');
+                src = data.src || '';
+              } else if (Array.isArray(data)) {
+                const chunks = data[0] || [];
+                translated = chunks.map((c) => (Array.isArray(c) ? c[0] : '')).join('');
+                src = data[2] || '';
+              }
+              return { text: String(translated || '').trim(), src: String(src || '').trim() };
+            }
+
+            const payload = context.payload;
+            const comment = payload.comment;
+            if (!comment || !comment.body) {
+              core.info('No comment body');
+              return;
+            }
+            if (comment.user && comment.user.type === 'Bot') {
+              core.info('Skip bot comment');
+              return;
+            }
+
+            const parent = payload.issue || payload.pull_request || payload.discussion;
+            if (!parent) {
+              core.info('No parent thread');
+              return;
+            }
+            const op = (parent.user && parent.user.login) || '';
+            if (op && context.actor === op) {
+              core.info('Skip OP comment');
+              return;
+            }
+
+            const parentText = `${originTitle(parent.title)}\n${origin(parent.body)}`.trim();
+            if (parentText.length < 8) {
+              core.info('Parent text too short to detect language');
+              return;
+            }
+
+            const commentText = origin(comment.body);
+            if (commentText.length < 3) {
+              core.info('Comment too short');
+              return;
+            }
+
+            let parentDet;
+            let commentDet;
+            try {
+              parentDet = await gtx(parentText, 'auto', 'en');
+              commentDet = await gtx(commentText, 'auto', 'en');
+            } catch (err) {
+              core.warning(`Detect failed: ${err.message}`);
+              return;
+            }
+
+            const opLang = parentDet.src;
+            const commentLang = commentDet.src;
+            core.info(`OP lang=${opLang || 'und'} comment lang=${commentLang || 'und'}`);
+            if (isEn(opLang)) {
+              core.info('OP is English; skip reverse');
+              return;
+            }
+            if (!isEn(commentLang)) {
+              core.info('Comment is not English; skip reverse');
+              return;
+            }
+
+            let translated;
+            try {
+              const out = await gtx(commentText, 'en', opLang);
+              translated = out.text;
+            } catch (err) {
+              core.warning(`Translate failed: ${err.message}`);
+              return;
+            }
+            if (!translated || translated === commentText) {
+              core.info('Empty or unchanged translation');
+              return;
+            }
+
+            const body = `${commentText}\n${DIV}\n---\n${translated}\n`;
+            const event = context.eventName;
+            if (event === 'discussion_comment') {
+              const id = comment.node_id;
+              if (!id) {
+                core.warning('Discussion comment missing node_id');
+                return;
+              }
+              await github.graphql(
+                `mutation ($id: ID!, $body: String!) {
+                  updateDiscussionComment(input: { commentId: $id, body: $body }) {
+                    comment { id }
+                  }
+                }`,
+                { id, body }
+              );
+              core.info('Updated discussion comment');
+              return;
+            }
+            if (event === 'pull_request_review_comment') {
+              await github.rest.pulls.updateReviewComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                comment_id: comment.id,
+                body
+              });
+              core.info('Updated review comment');
+              return;
+            }
+            await github.rest.issues.updateComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              comment_id: comment.id,
+              body
+            });
+            core.info('Updated issue comment');