fix(sync): paginate compare and resolve real head SHA

packages/backend/convex/githubClient.ts

@@ -117,6 +117,9 @@ const normalizeCompareCommit = (
   htmlUrl: commit.html_url,
 });
 
+const COMPARE_PER_PAGE = 100;
+const COMPARE_MAX_PAGES = 30; // bound: up to 3000 commits collected
+
 export const compareAcrossForkNetwork = async (
   octokit: Octokit,
   args: {
@@ -125,24 +128,46 @@ export const compareAcrossForkNetwork = async (
     baseOwner: string;
     baseBranch: string;
     headOwner: string;
+    headRepo: string;
     headBranch: string;
   },
 ): Promise<GitHubCompareSummary> => {
   const basehead = `${args.baseOwner}:${args.baseBranch}...${args.headOwner}:${args.headBranch}`;
-  const result = await octokit.rest.repos.compareCommitsWithBasehead({
+  const first = await octokit.rest.repos.compareCommitsWithBasehead({
     owner: args.owner,
     repo: args.repo,
     basehead,
-    per_page: 100,
+    per_page: COMPARE_PER_PAGE,
+    page: 1,
   });
-  const commits = result.data.commits.map(normalizeCompareCommit);
+  const rawCommits = [...first.data.commits];
+  const totalCommits = first.data.total_commits;
+  let page = 2;
+  while (rawCommits.length < totalCommits && page <= COMPARE_MAX_PAGES) {
+    const next = await octokit.rest.repos.compareCommitsWithBasehead({
+      owner: args.owner,
+      repo: args.repo,
+      basehead,
+      per_page: COMPARE_PER_PAGE,
+      page,
+    });
+    if (next.data.commits.length === 0) break;
+    rawCommits.push(...next.data.commits);
+    page += 1;
+  }
+  const head = await resolveBranchHead(
+    octokit,
+    args.headOwner,
+    args.headRepo,
+    args.headBranch,
+  );
   return {
-    aheadBy: result.data.ahead_by,
-    mergeBaseSha: result.data.merge_base_commit.sha,
-    headSha: commits[commits.length - 1]?.sha,
-    baseSha: result.data.base_commit.sha,
-    htmlUrl: result.data.html_url,
-    commits,
+    aheadBy: first.data.ahead_by,
+    mergeBaseSha: first.data.merge_base_commit.sha,
+    headSha: head.sha,
+    baseSha: first.data.base_commit.sha,
+    htmlUrl: first.data.html_url,
+    commits: rawCommits.map(normalizeCompareCommit),
   };
 };