diff --git a/src/app/api/metrics/activity/route.ts b/src/app/api/metrics/activity/route.ts
index 648696291..e4f708916 100644
--- a/src/app/api/metrics/activity/route.ts
+++ b/src/app/api/metrics/activity/route.ts
@@ -74,7 +74,7 @@ async function fetchDiscussionItemsViaGraphQL(
       token
     );
     const nodes = data?.viewer?.repositoryDiscussionComments?.nodes ?? [];
-    return nodes.map(formatGraphQLDiscussionComment);
+    return (nodes ?? []).map(formatGraphQLDiscussionComment);
   } catch {
     // Discussions may be disabled, rate-limited, or the token may lack the
     // required scope — never allow this to block the main activity feed.
@@ -167,9 +167,9 @@ export async function GET(req: NextRequest) {
   let limit = limitParam ? parseInt(limitParam, 10) : 10;
   let offset = offsetParam ? parseInt(offsetParam, 10) : 0;
 
-  if (isNaN(limit) || limit < 1) limit = 10;
+  if (Number.isNaN(limit) || limit < 1) limit = 10;
   if (limit > 100) limit = 100;
-  if (isNaN(offset) || offset < 0) offset = 0;
+  if (Number.isNaN(offset) || offset < 0) offset = 0;
 
   const bypass = isMetricsCacheBypassed(req);
   const cacheKey = metricsCacheKey(
diff --git a/src/app/api/metrics/contributions/hourly/route.ts b/src/app/api/metrics/contributions/hourly/route.ts
index 6c8740c62..ffdf11c98 100644
--- a/src/app/api/metrics/contributions/hourly/route.ts
+++ b/src/app/api/metrics/contributions/hourly/route.ts
@@ -19,7 +19,7 @@ export async function GET(req: NextRequest) {
 
   const daysParam = req.nextUrl.searchParams.get("days");
   const parsedDays = daysParam ? parseInt(daysParam, 10) : NaN;
-  const days = isNaN(parsedDays) ? 30 : Math.max(1, Math.min(365, parsedDays));
+  const days = Number.isNaN(parsedDays) ? 30 : Math.max(1, Math.min(365, parsedDays));
   const bypass = isMetricsCacheBypassed(req);
   const key = metricsCacheKey(
     session.githubId ?? session.githubLogin,
diff --git a/src/app/api/metrics/contributions/route.ts b/src/app/api/metrics/contributions/route.ts
index 225440241..ed17262c5 100644
--- a/src/app/api/metrics/contributions/route.ts
+++ b/src/app/api/metrics/contributions/route.ts
@@ -155,7 +155,7 @@ async function fetchContributionsForAccount(
       if (orgName) {
         q += ` org:${orgName}`;
       } else if (excludedOrgs.length > 0) {
-        q += excludedOrgs.map((org) => ` -org:${org}`).join("");
+        q += (excludedOrgs ?? []).map((org) => ` -org:${org}`).join("");
       }
 
       // Note: this may issue up to 10 sequential GitHub Search API calls (max 1000 results).
@@ -383,7 +383,7 @@ export async function GET(req: NextRequest) {
   } else {
     const daysParam = req.nextUrl.searchParams.get("days");
     const parsedDays = daysParam ? parseInt(daysParam, 10) : NaN;
-    days = isNaN(parsedDays) ? 30 : Math.max(1, Math.min(365, parsedDays));
+    days = Number.isNaN(parsedDays) ? 30 : Math.max(1, Math.min(365, parsedDays));
   }
 
   const accountId = req.nextUrl.searchParams.get("accountId");
diff --git a/src/app/api/metrics/productive-hours/route.ts b/src/app/api/metrics/productive-hours/route.ts
index 5bb62d383..1c73e77af 100644
--- a/src/app/api/metrics/productive-hours/route.ts
+++ b/src/app/api/metrics/productive-hours/route.ts
@@ -223,7 +223,7 @@ export async function GET(req: NextRequest) {
   } else {
     const daysParam = searchParams.get("days");
     const parsedDays = daysParam ? parseInt(daysParam, 10) : NaN;
-    days = isNaN(parsedDays) ? 90 : Math.max(1, Math.min(365, parsedDays));
+    days = Number.isNaN(parsedDays) ? 90 : Math.max(1, Math.min(365, parsedDays));
   }
 
   const accountId = searchParams.get("accountId");
@@ -268,7 +268,7 @@ export async function GET(req: NextRequest) {
     );
 
     const results = await Promise.allSettled(
-      accounts.map((account) =>
+      (accounts ?? []).map((account) =>
         fetchProductiveHoursForAccount(
           account.token,
           account.githubLogin,
diff --git a/src/app/api/metrics/repos/route.ts b/src/app/api/metrics/repos/route.ts
index 11ef12f67..e703bf9f1 100644
--- a/src/app/api/metrics/repos/route.ts
+++ b/src/app/api/metrics/repos/route.ts
@@ -145,7 +145,7 @@ async function fetchReposForAccount(
       if (orgName) {
         q += `+org:${orgName}`;
       } else if (excludedOrgs.length > 0) {
-        q += excludedOrgs.map((org) => `+-org:${org}`).join("");
+        q += (excludedOrgs ?? []).map((org) => `+-org:${org}`).join("");
       }
       q += `+author-date:>=${sinceStr}`;
 
@@ -238,7 +238,7 @@ export async function GET(req: NextRequest) {
   const daysParam = req.nextUrl.searchParams.get("days");
   const parsedDays = daysParam ? parseInt(daysParam, 10) : NaN;
   // Clamp days between 1 and 365 — GitHub Commit Search supports up to ~1 year lookback.
-  const days = isNaN(parsedDays) ? 30 : Math.max(1, Math.min(365, parsedDays));
+  const days = Number.isNaN(parsedDays) ? 30 : Math.max(1, Math.min(365, parsedDays));
   const accountId = req.nextUrl.searchParams.get("accountId");
   const bypass = isMetricsCacheBypassed(req);