From 89bfb4d952051091cfc7c85ff982b0e865a3b1ff Mon Sep 17 00:00:00 2001
From: shigahi <masanari.higashi@classmethod.de>
Date: Thu, 22 Jan 2026 23:48:58 +0100
Subject: [PATCH] Add Cache-Control header optimization

- Add CachingOptions interface with htmlTtl, staticAssetsTtl, imageTtl
- Add applyCacheHeaders function to set Cache-Control based on content type
- Apply cache headers to JS, CSS, images, and HTML responses
- Add Caching section in UI with TTL configuration inputs

Closes #33
---
 src/App.tsx | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/code.ts | 57 ++++++++++++++++++++++++++++-----
 2 files changed, 141 insertions(+), 7 deletions(-)

diff --git a/src/App.tsx b/src/App.tsx
index 6437c31..d7b4a50 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -44,6 +44,7 @@ import code, {
   BrandingOptions,
   SeoOptions,
   AnalyticsOptions,
+  CachingOptions,
   CustomHtmlOptions,
   Custom404Options,
   SubdomainRedirect,
@@ -162,6 +163,12 @@ export default function App() {
   const [analytics, setAnalytics] = useState<AnalyticsOptions>({
     googleTagId: "",
   });
+  const [caching, setCaching] = useState<CachingOptions>({
+    enabled: false,
+    htmlTtl: 60,
+    staticAssetsTtl: 86400,
+    imageTtl: 604800,
+  });
   const [customHtml, setCustomHtml] = useState<CustomHtmlOptions>({
     headerHtml: "",
   });
@@ -288,6 +295,17 @@ export default function App() {
     setCopied(false);
   }
 
+  function handleCachingChange(
+    field: keyof CachingOptions,
+    value: boolean | number,
+  ): void {
+    setCaching({
+      ...caching,
+      [field]: value,
+    });
+    setCopied(false);
+  }
+
   function handleCustomHtmlChange(
     field: keyof CustomHtmlOptions,
     value: string,
@@ -400,6 +418,7 @@ export default function App() {
     branding,
     seo,
     analytics,
+    caching,
     customHtml,
     custom404,
     subdomainRedirects,
@@ -930,6 +949,78 @@ export default function App() {
                 />
               </Box>
 
+              <Box sx={{ mt: 3, pt: 2, borderTop: 1, borderColor: "grey.300" }}>
+                <Stack
+                  direction="row"
+                  alignItems="center"
+                  justifyContent="space-between"
+                >
+                  <Box>
+                    <Typography variant="subtitle2" color="text.secondary">
+                      Cache-Control Headers
+                    </Typography>
+                    <Typography variant="caption" color="text.secondary">
+                      Improve performance with browser caching
+                    </Typography>
+                  </Box>
+                  <Switch
+                    checked={caching.enabled}
+                    onChange={(e) =>
+                      handleCachingChange("enabled", e.target.checked)
+                    }
+                  />
+                </Stack>
+                <Collapse in={caching.enabled} timeout="auto" unmountOnExit>
+                  <Box sx={{ mt: 2 }}>
+                    <TextField
+                      fullWidth
+                      type="number"
+                      label="HTML Page TTL (seconds)"
+                      margin="dense"
+                      placeholder="60"
+                      helperText="Cache duration for HTML pages (default: 60s)"
+                      onChange={(e) =>
+                        handleCachingChange("htmlTtl", Number(e.target.value))
+                      }
+                      value={caching.htmlTtl}
+                      variant="outlined"
+                      size="small"
+                    />
+                    <TextField
+                      fullWidth
+                      type="number"
+                      label="Static Assets TTL (seconds)"
+                      margin="dense"
+                      placeholder="86400"
+                      helperText="Cache duration for JS, CSS, fonts (default: 1 day)"
+                      onChange={(e) =>
+                        handleCachingChange(
+                          "staticAssetsTtl",
+                          Number(e.target.value),
+                        )
+                      }
+                      value={caching.staticAssetsTtl}
+                      variant="outlined"
+                      size="small"
+                    />
+                    <TextField
+                      fullWidth
+                      type="number"
+                      label="Image TTL (seconds)"
+                      margin="dense"
+                      placeholder="604800"
+                      helperText="Cache duration for images (default: 1 week)"
+                      onChange={(e) =>
+                        handleCachingChange("imageTtl", Number(e.target.value))
+                      }
+                      value={caching.imageTtl}
+                      variant="outlined"
+                      size="small"
+                    />
+                  </Box>
+                </Collapse>
+              </Box>
+
               <Box sx={{ mt: 3, pt: 2, borderTop: 1, borderColor: "grey.300" }}>
                 <Typography
                   variant="subtitle2"
diff --git a/src/code.ts b/src/code.ts
index 921232b..c5ce3c3 100644
--- a/src/code.ts
+++ b/src/code.ts
@@ -38,6 +38,13 @@ export interface AnalyticsOptions {
   googleTagId?: string;
 }
 
+export interface CachingOptions {
+  enabled: boolean;
+  htmlTtl?: number;
+  staticAssetsTtl?: number;
+  imageTtl?: number;
+}
+
 export interface CustomHtmlOptions {
   headerHtml?: string;
 }
@@ -66,6 +73,7 @@ export interface CodeData {
   branding: BrandingOptions;
   seo: SeoOptions;
   analytics: AnalyticsOptions;
+  caching: CachingOptions;
   customHtml: CustomHtmlOptions;
   custom404: Custom404Options;
   subdomainRedirects: SubdomainRedirect[];
@@ -97,6 +105,7 @@ export default function code(data: CodeData): string {
     branding,
     seo,
     analytics,
+    caching,
     customHtml,
     custom404,
     subdomainRedirects,
@@ -164,6 +173,15 @@ ${slugs
    */
   const GOOGLE_TAG_ID = '${analytics?.googleTagId || ""}';
 
+  /*
+   * Step 3.5.1: caching configuration (optional)
+   * Add Cache-Control headers for better performance
+   */
+  const CACHING_ENABLED = ${caching?.enabled || false};
+  const HTML_TTL = ${caching?.htmlTtl || 60};
+  const STATIC_ASSETS_TTL = ${caching?.staticAssetsTtl || 86400};
+  const IMAGE_TTL = ${caching?.imageTtl || 604800};
+
   /*
    * Step 3.6: custom HTML header injection (optional)
    * Add custom HTML to the top of the page body (e.g., navigation, announcements)
@@ -248,6 +266,29 @@ ${
     return options;
   }
 
+  // Apply Cache-Control headers based on content type (Issue #33)
+  function applyCacheHeaders(response, url, contentType) {
+    if (!CACHING_ENABLED) return response;
+
+    const newResponse = new Response(response.body, response);
+    const pathname = url.pathname;
+
+    // Static assets (JS, CSS, fonts)
+    if (pathname.match(/\\.(js|css|woff2?|ttf|eot)$/)) {
+      newResponse.headers.set('Cache-Control', \`public, max-age=\${STATIC_ASSETS_TTL}, immutable\`);
+    }
+    // Images
+    else if (pathname.startsWith('/image') || pathname.match(/\\.(jpg|jpeg|png|gif|webp|avif|svg|ico)$/)) {
+      newResponse.headers.set('Cache-Control', \`public, max-age=\${IMAGE_TTL}\`);
+    }
+    // HTML pages
+    else if (!contentType || contentType.includes('text/html')) {
+      newResponse.headers.set('Cache-Control', \`public, max-age=\${HTML_TTL}, stale-while-revalidate=60\`);
+    }
+
+    return newResponse;
+  }
+
   function generateSitemap() {
     let sitemap = '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">';
     slugs.forEach(
@@ -340,7 +381,7 @@ ${
       body = rewriteDomainInBody(body);
       response = new Response(body, response);
       response.headers.set('Content-Type', 'application/x-javascript');
-      return response;
+      return applyCacheHeaders(response, url, 'application/javascript');
     } else if (url.pathname.startsWith('/_assets/') && url.pathname.endsWith('.js')) {
       // Handle Notion's new asset paths
       response = await fetch(url.toString());
@@ -348,7 +389,7 @@ ${
       body = rewriteDomainInBody(body);
       response = new Response(body, response);
       response.headers.set('Content-Type', 'application/javascript');
-      return response;
+      return applyCacheHeaders(response, url, 'application/javascript');
     } else if (url.pathname.startsWith('/api/v3/getPublicPageData')) {
       // Proxy getPublicPageData and rewrite domain info
       response = await fetch(url.toString(), {
@@ -415,7 +456,7 @@ ${
       return response;
     } else if (url.pathname.startsWith('/image') && IMAGE_OPTIMIZATION !== 'none') {
       const response = await fetch(url, rewriteImageOptions());
-      return response;
+      return applyCacheHeaders(response, url, 'image');
     } else if (slugs.indexOf(url.pathname.slice(1)) > -1) {
       const pageId = SLUG_TO_PAGE[url.pathname.slice(1)];
        return Response.redirect('https://' + MY_DOMAIN + '/' + pageId, 302);
@@ -446,14 +487,14 @@ ${
       });
       response.headers.delete('Content-Security-Policy');
       response.headers.delete('X-Content-Security-Policy');
-      return appendJavascript(response, SLUG_TO_PAGE, '404');
+      return appendJavascript(response, SLUG_TO_PAGE, '404', url);
     }
 
     // Get current slug from page ID for canonical URL
     const pageId = url.pathname.slice(-32);
     const currentSlug = PAGE_TO_SLUG[pageId] || '';
 
-    return appendJavascript(response, SLUG_TO_PAGE, currentSlug);
+    return appendJavascript(response, SLUG_TO_PAGE, currentSlug, url);
   }
 
   class MetaRewriter {
@@ -744,16 +785,18 @@ ${
     }
   }
 
-  async function appendJavascript(res, SLUG_TO_PAGE, slug) {
+  async function appendJavascript(res, SLUG_TO_PAGE, slug, url) {
     const metaRewriter = new MetaRewriter(slug);
     const headRewriter = new HeadRewriter(slug);
     const linkRewriter = new LinkRewriter();
-    return new HTMLRewriter()
+    const contentType = res.headers.get('content-type');
+    let transformed = new HTMLRewriter()
       .on('title', metaRewriter)
       .on('meta', metaRewriter)
       .on('link', linkRewriter)
       .on('head', headRewriter)
       .on('body', new BodyRewriter(SLUG_TO_PAGE))
       .transform(res);
+    return applyCacheHeaders(transformed, url, contentType);
   }`;
 }