merge: fix: update cache control headers to s-maxage=1 to prevent stale data… (#7821)

## Description

Fixes #7803

The SVG endpoints (such as `/api/streak`, `/api/stats`, etc.) were
previously setting a `Cache-Control` header of `s-maxage=3600`. Because
GitHub caches external images using its own Camo proxy, this high
max-age meant that users wouldn't see their updated commit stats for up
to an hour after making a contribution.

This PR updates the `buildCacheControlHeader` utility and all associated
API routes to return `s-maxage=1, stale-while-revalidate=59`. This
dramatically reduces the hard caching duration while still allowing CDNs
to serve stale content gracefully while revalidating in the background,
ensuring near real-time updates for SVG widgets embedded in READMEs. All
relevant unit tests testing cache bounds were updated to reflect this
new optimal configuration.

## Pillar

- [ ] 🎨 Pillar 1 — New Theme Design
- [ ] 📐 Pillar 2 — Geometric SVG Improvement
- [ ] 🕐 Pillar 3 — Timezone Logic Optimization
- [x] 🛠️ Other (Bug fix, refactoring, docs)

## Checklist before requesting a review:

- [x] I have read the `CONTRIBUTING.md` file.
- [x] I have tested these changes locally
(`localhost:3000/api/streak?user=YOUR_USERNAME`).
- [x] I have run `npm run format` and `npm run lint` locally and
resolved all errors (CI will fail otherwise).
- [x] My commits follow the Conventional Commits format (e.g.,
`feat(themes): ...`, `fix(calculate): ...`).
- [ ] I have updated `README.md` if I added a new theme or URL
parameter.
- [x] I have started the repo.
- [x] I have made sure that i have only one commit to merge in this PR.
- [x] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (no raw elements, smooth animations, correct fonts).
- [x] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: JhaSourav07

app/api/compare/route.empty-fallback.test.ts

@@ -66,7 +66,7 @@ describe('GET /api/compare - Empty & Missing Input Fallbacks', () => {
     const res = await GET(makeRequest('user1=alice&user2=bob'));
     expect(res.status).toBe(200);
     expect(res.headers.get('ETag')).toBeTruthy();
-    expect(res.headers.get('Cache-Control')).toBe('public, s-maxage=3600');
+    expect(res.headers.get('Cache-Control')).toBe('public, s-maxage=1');
   });
 
   it('returns 200 when If-None-Match is an empty string instead of crashing', async () => {

app/api/compare/route.test.ts

@@ -181,7 +181,7 @@ describe('GET /api/compare', () => {
     const res = await GET(makeRequest('user1=alice&user2=bob'));
     expect(res.status).toBe(200);
     expect(res.headers.get('ETag')).toBeTruthy();
-    expect(res.headers.get('Cache-Control')).toBe('public, s-maxage=3600');
+    expect(res.headers.get('Cache-Control')).toBe('public, s-maxage=1');
   });
 
   it('returns 304 Not Modified when If-None-Match matches weak ETag', async () => {
@@ -199,7 +199,7 @@ describe('GET /api/compare', () => {
     expect(res2.status).toBe(304);
     expect(res2.body).toBeNull();
     expect(res2.headers.get('ETag')).toBe(etag);
-    expect(res2.headers.get('Cache-Control')).toBe('public, s-maxage=3600');
+    expect(res2.headers.get('Cache-Control')).toBe('public, s-maxage=1');
   });
 
   it('returns 304 Not Modified when If-None-Match matches strong ETag', async () => {

app/api/compare/route.ts

@@ -103,7 +103,7 @@ export async function GET(request: Request) {
     const etag = crypto.createHash('sha1').update(jsonPayload).digest('hex');
     const weakEtag = `W/"${etag}"`;
     const ifNoneMatch = request.headers.get('if-none-match');
-    const cacheControl = 'public, s-maxage=3600';
+    const cacheControl = 'public, s-maxage=1';
 
     if (ifNoneMatch) {
       const etags = ifNoneMatch.split(',').map((e) => e.trim());

app/api/github/route.ts

@@ -173,7 +173,7 @@ export async function GET(request: Request) {
 
     const cacheControl = shouldBypassCache
       ? 'no-cache, no-store, must-revalidate'
-      : 's-maxage=3600, stale-while-revalidate=86400';
+      : 's-maxage=1, stale-while-revalidate=59';
 
     const cacheStatus = shouldBypassCache ? 'MISS' : 'HIT';
 

app/api/repo-burnout/route.ts

@@ -97,7 +97,7 @@ export async function GET(request: Request) {
 
     const cacheControl = shouldBypassCache
       ? 'no-cache, no-store, must-revalidate'
-      : 's-maxage=3600, stale-while-revalidate=86400';
+      : 's-maxage=1, stale-while-revalidate=59';
 
     return NextResponse.json(data, {
       status: 200,

app/api/spotlight/route.ts

@@ -104,7 +104,7 @@ export async function GET(request: Request) {
       return new NextResponse(null, {
         status: 304,
         headers: {
-          'Cache-Control': 'public, max-age=60, s-maxage=3600, stale-while-revalidate=60',
+          'Cache-Control': 'public, max-age=60, s-maxage=1, stale-while-revalidate=59',
           ETag: weakEtag,
         },
       });
@@ -113,7 +113,7 @@ export async function GET(request: Request) {
     return new NextResponse(svg, {
       headers: {
         'Content-Type': 'image/svg+xml; charset=utf-8',
-        'Cache-Control': 'public, max-age=60, s-maxage=3600, stale-while-revalidate=60',
+        'Cache-Control': 'public, max-age=60, s-maxage=1, stale-while-revalidate=59',
         'Content-Security-Policy': SVG_CSP_HEADER,
         ETag: weakEtag,
       },

app/api/stats/route.test.ts

@@ -141,7 +141,7 @@ describe('GET /api/stats', () => {
 
     expect(response.status).toBe(200);
     expect(response.headers.get('Cache-Control')).toBe(
-      'public, s-maxage=3600, stale-while-revalidate=86400'
+      'public, s-maxage=1, stale-while-revalidate=59'
     );
     expect(response.headers.get('Pragma')).toBeNull();
     expect(response.headers.get('Expires')).toBeNull();
@@ -168,7 +168,7 @@ describe('GET /api/stats', () => {
     });
     expect(response.headers.get('X-Refresh-Status')).toBe('Cooldown-Served-Cached');
     expect(response.headers.get('Cache-Control')).toBe(
-      'public, s-maxage=3600, stale-while-revalidate=86400'
+      'public, s-maxage=1, stale-while-revalidate=59'
     );
   });
 

app/api/stats/route.ts

@@ -134,7 +134,7 @@ export async function GET(request: Request) {
     const stats = calculateStreak(calendar, timezone);
     const headers = new Headers({
       // Cache until next UTC midnight; clients can bust with ?refresh=true
-      'Cache-Control': 'public, s-maxage=3600, stale-while-revalidate=86400',
+      'Cache-Control': 'public, s-maxage=1, stale-while-revalidate=59',
     });
 
     if (shouldBypassCache) {

app/api/stats/route.validation.test.ts

@@ -113,7 +113,7 @@ describe('GET /api/stats additional runtime coverage', () => {
     expect(response.status).toBe(200);
 
     expect(response.headers.get('Cache-Control')).toBe(
-      'public, s-maxage=3600, stale-while-revalidate=86400'
+      'public, s-maxage=1, stale-while-revalidate=59'
     );
     expect(response.headers.get('Pragma')).toBeNull();
     expect(response.headers.get('Expires')).toBeNull();

app/api/streak/route.test.ts

@@ -443,15 +443,15 @@ describe('GET /api/streak', () => {
     it('caches until UTC midnight by default, using the value from getSecondsUntilUTCMidnight', async () => {
       const response = await GET(makeRequest({ user: 'octocat' }));
       expect(response.headers.get('Cache-Control')).toBe(
-        'public, max-age=60, s-maxage=3600, stale-while-revalidate=60'
+        'public, max-age=60, s-maxage=1, stale-while-revalidate=59'
       );
     });
 
     it('reflects a different time value when the clock changes', async () => {
       vi.mocked(getSecondsUntilUTCMidnight).mockReturnValue(7200);
       const response = await GET(makeRequest({ user: 'octocat' }));
       expect(response.headers.get('Cache-Control')).toBe(
-        'public, max-age=60, s-maxage=7200, stale-while-revalidate=60'
+        'public, max-age=60, s-maxage=1, stale-while-revalidate=59'
       );
     });
 
@@ -1013,7 +1013,7 @@ describe('GET /api/streak', () => {
       const response = await GET(makeRequest({ user: 'octocat', tz: 'America/New_York' }));
 
       expect(response.headers.get('Cache-Control')).toBe(
-        'public, max-age=60, s-maxage=7200, stale-while-revalidate=60'
+        'public, max-age=60, s-maxage=1, stale-while-revalidate=59'
       );
       expect(getSecondsUntilMidnightInTimezone).toHaveBeenCalledWith('America/New_York');
       expect(getSecondsUntilUTCMidnight).not.toHaveBeenCalled();
@@ -1571,16 +1571,16 @@ describe('GET /api/streak', () => {
   });
 
   describe('stale-while-revalidate cache header', () => {
-    it('contains stale-while-revalidate=60 for normal request', async () => {
+    it('contains stale-while-revalidate=59 for normal request', async () => {
       const response = await GET(makeRequest({ user: 'octocat' }));
 
-      expect(response.headers.get('Cache-Control')).toContain('stale-while-revalidate=60');
+      expect(response.headers.get('Cache-Control')).toContain('stale-while-revalidate=59');
     });
 
     it('does NOT contain stale-while-revalidate when ?refresh=true', async () => {
       const response = await GET(makeRequest({ user: 'octocat', refresh: 'true' }));
 
-      expect(response.headers.get('Cache-Control')).not.toContain('stale-while-revalidate=60');
+      expect(response.headers.get('Cache-Control')).not.toContain('stale-while-revalidate=59');
     });
   });