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

packages/backend/convex/githubSync.ts

@@ -32,8 +32,13 @@ const toStatus = (upstreamAheadBy: number, forkAheadBy: number) => {
   return 'unknown' as const;
 };
 
-const getLastCommitAt = (compare: GitHubCompareSummary) =>
-  compare.commits[compare.commits.length - 1]?.committedAt;
+const getLastCommitAt = (compare: GitHubCompareSummary) => {
+  const head = compare.commits.find((c) => c.sha === compare.headSha);
+  return (
+    head?.committedAt ??
+    compare.commits[compare.commits.length - 1]?.committedAt
+  );
+};
 
 const ensureForkMetadata = (spoon: Doc<'spoons'>) => {
   if (!spoon.forkOwner || !spoon.forkRepo) {
@@ -121,6 +126,7 @@ const refreshOwnedSpoon = async (
         baseOwner: forkOwner,
         baseBranch: resolvedForkBranch,
         headOwner: spoon.upstreamOwner,
+        headRepo: spoon.upstreamRepo,
         headBranch: upstreamBranch,
       }),
       compareAcrossForkNetwork(octokit, {
@@ -129,6 +135,7 @@ const refreshOwnedSpoon = async (
         baseOwner: spoon.upstreamOwner,
         baseBranch: upstreamBranch,
         headOwner: forkOwner,
+        headRepo: forkRepo,
         headBranch: resolvedForkBranch,
       }),
       listPullRequests(octokit, { owner: forkOwner, repo: forkRepo }),