From 61df40744c391035919be440a8aa90c4a0db6f80 Mon Sep 17 00:00:00 2001
From: Zach Harel <zach@zharel.me>
Date: Thu, 3 Sep 2026 19:33:07 -0400
Subject: [PATCH] Enhance preview comment functionality to list changed pages

---
 .github/workflows/preview.yml | 43 +++++++++++++++++++++++++++++++----
 1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/preview.yml b/.github/workflows/preview.yml
index 2d296b95..84b00bbc 100644
--- a/.github/workflows/preview.yml
+++ b/.github/workflows/preview.yml
@@ -69,6 +69,8 @@ jobs:
             - name: Comment PR with preview URL
               if: success()
               uses: actions/github-script@v9
+              env:
+                  WRANGLER_OUTPUT: ${{ steps.upload.outputs.command-output }}
               with:
                   script: |
                       const prNumber = parseInt('${{ steps.get-pr.outputs.pr-number }}');
@@ -83,19 +85,52 @@ jobs:
                           `$1${alias}-`,
                       );
 
+                      // wrangler lists each newly uploaded asset as "+ /some/path/index.html"
+                      const uploaded = (process.env.WRANGLER_OUTPUT || '')
+                          .split('\n')
+                          .map(line => line.replace(/\[[0-9;]*m/g, '').trim())
+                          .map(line => /^\+\s+(\/\S*)$/.exec(line)?.[1])
+                          .filter(path => path && path.endsWith('.html'));
+
+                      const pages = [...new Set(uploaded)]
+                          .map(path => path.replace(/index\.html$/, '').replace(/\.html$/, '/'))
+                          .sort();
+
+                      const pageList = pages.length
+                          ? pages
+                                .map(path => `- [${path}](${previewUrl}${path})`)
+                                .join('\n')
+                          : '_No changed pages detected._';
+
+                      const marker = '<!-- preview-url-comment -->';
+                      const body = [
+                          marker,
+                          `🌐 Preview URL: ${previewUrl}`,
+                          '',
+                          '**Changed pages**',
+                          pageList,
+                      ].join('\n');
+
                       const { data: comments } = await github.rest.issues.listComments({
                           owner: context.repo.owner,
                           repo: context.repo.repo,
                           issue_number: prNumber,
                       });
-                      const alreadyCommented = comments.some(
-                          c => c.user?.type === 'Bot' && c.body?.includes(previewUrl)
+                      const existing = comments.find(
+                          c => c.user?.type === 'Bot' && c.body?.includes(marker)
                       );
-                      if (!alreadyCommented) {
+                      if (existing) {
+                          await github.rest.issues.updateComment({
+                              owner: context.repo.owner,
+                              repo: context.repo.repo,
+                              comment_id: existing.id,
+                              body,
+                          });
+                      } else {
                           await github.rest.issues.createComment({
                               owner: context.repo.owner,
                               repo: context.repo.repo,
                               issue_number: prNumber,
-                              body: `🌐 Preview URL: ${previewUrl}`,
+                              body,
                           });
                       }