chore: fix eslint errors introduced in phase 4 backend

packages/backend/convex/githubWebhookVerify.ts

@@ -17,7 +17,7 @@ export const verifyGithubSignature = async (
   rawBody: string,
   signatureHeader: string | null,
 ): Promise<boolean> => {
-  if (!signatureHeader || !signatureHeader.startsWith('sha256=')) return false;
+  if (!signatureHeader?.startsWith('sha256=')) return false;
   // Web Crypto's importKey throws on a zero-length HMAC key; guard so the
   // verifier never throws on attacker-controlled input (returns false instead).
   if (!secret) return false;

packages/backend/convex/maintenanceDedup.ts

@@ -16,6 +16,9 @@ export const maintenanceDedupKey = (input: {
 }): string | null => {
   const head = input.headSha?.trim();
   if (!head) return null;
+  // Intentional `||`: an empty/whitespace merge base must collapse to the
+  // 'nobase' sentinel, which `??` would not do (it keeps the empty string).
+  // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
   const base = input.mergeBaseSha?.trim() || 'nobase';
   return `${base}:${head}`;
 };

packages/backend/tests/unit/github-head.test.ts

@@ -8,9 +8,9 @@ import {
 
 describe('resolveBranchHead', () => {
   it('returns the branch tip sha from the branch ref', async () => {
-    const getBranch = vi.fn(async () => ({
-      data: { commit: { sha: 'deadbeef' } },
-    }));
+    const getBranch = vi.fn(() =>
+      Promise.resolve({ data: { commit: { sha: 'deadbeef' } } }),
+    );
     const octokit = {
       rest: { repos: { getBranch } },
     } as unknown as Octokit;
@@ -45,10 +45,9 @@ describe('compareAcrossForkNetwork', () => {
       makeCommit(i === 49 ? 'LAST_COMMIT_NOT_TIP' : `c${100 + i}`),
     );
 
-    const compareCommitsWithBasehead = vi.fn(
-      async ({ page }: { page?: number }) => {
+    const compareCommitsWithBasehead = vi.fn(({ page }: { page?: number }) => {
       const commits = page === 2 ? page2 : page1;
-        return {
+      return Promise.resolve({
         data: {
           total_commits: 150,
           ahead_by: 150,
@@ -57,12 +56,11 @@ describe('compareAcrossForkNetwork', () => {
           html_url: 'https://github.com/o/r/compare/base...head',
           commits,
         },
-        };
-      },
+      });
+    });
+    const getBranch = vi.fn(() =>
+      Promise.resolve({ data: { commit: { sha: 'TIP' } } }),
     );
-    const getBranch = vi.fn(async () => ({
-      data: { commit: { sha: 'TIP' } },
-    }));
     const octokit = {
       rest: { repos: { compareCommitsWithBasehead, getBranch } },
     } as unknown as Octokit;