Refactor cache control settings and improve robots.txt handling; update definition retrieval to synchronous method

hdyc-svelte/src/hooks.server.ts

@@ -12,7 +12,8 @@ const MIME_TYPES: Record<string, string> = {
   '.otf': 'font/otf'
 };
 
-const HTML_CACHE_CONTROL = 'public, max-age=0, s-maxage=3600, stale-while-revalidate=86400';
+const HTML_CACHE_CONTROL = 'no-cache, max-age=0, must-revalidate, no-transform';
+const EDGE_HTML_CACHE_CONTROL = 'max-age=300, stale-while-revalidate=86400';
 const IMMUTABLE_ASSET_CACHE_CONTROL = 'public, max-age=31536000, immutable';
 const ASSET_404_CACHE_CONTROL = 'no-store';
 const LONG_CACHE_EXTENSIONS = new Set([
@@ -71,6 +72,8 @@ export const handle: Handle = async ({ event, resolve }) => {
   // bundle hashes after each deployment.
   if (contentType.includes('text/html')) {
     response.headers.set('cache-control', HTML_CACHE_CONTROL);
+    response.headers.set('cdn-cache-control', EDGE_HTML_CACHE_CONTROL);
+    response.headers.set('cloudflare-cdn-cache-control', EDGE_HTML_CACHE_CONTROL);
   }
 
   return response;

hdyc-svelte/src/lib/components/QuickConversionExample.svelte

@@ -39,14 +39,10 @@
 {#if supportsExample && result}
   <section class="example-card">
     <h3>How to convert {config.labels.in1} to {config.labels.in2}</h3>
-    {#if hasOffset}
-      <p class="example-note">
-        Formula: {config.labels.in2} = ({config.labels.in1} x {formattedFactorValue}) {offset > 0 ? '+' : '-'} {formatConversionValue(Math.abs(offset))}
-      </p>
-    {:else}
-      <p class="example-note">
-        1 {config.labels.in1} = {formattedFactorValue} {config.labels.in2}
-      </p>
+    <p class="example-note">
+      1 {config.labels.in1} = {formattedFactorValue}{hasOffset ? ` + ${formattedOffsetValue}` : ''} {config.labels.in2}
+    </p>
+    {#if !hasOffset}
       <p class="example-note">
         1 {config.labels.in2} = {formattedReverseValue} {config.labels.in1}
       </p>

hdyc-svelte/src/lib/components/QuickDefinitionCard.svelte

@@ -1,20 +1,18 @@
 <script lang="ts">
-  import { getDefinition } from '$lib/data/unitDefinitions';
-  import type { CalculatorDef } from '$lib/data/calculatorLoader';
+  import { getDefinitionSync } from '$lib/data/unitDefinitions';
+  import type { CalculatorDef } from '$lib/data/calculators';
 
   export let config: CalculatorDef;
 
   let label1 = 'Unit 1';
   let label2 = 'Unit 2';
-  let def1: string | undefined;
-  let def2: string | undefined;
+  let def1 = '';
+  let def2 = '';
 
   $: label1 = config.labels.in1 || 'Unit 1';
   $: label2 = config.labels.in2 || 'Unit 2';
-  $: {
-    getDefinition(label1, config.category).then(d => { def1 = d; });
-    getDefinition(label2, config.category).then(d => { def2 = d; });
-  }
+  $: def1 = getDefinitionSync(label1, config.category) ?? '';
+  $: def2 = getDefinitionSync(label2, config.category) ?? '';
 </script>
 
 <section class="definition-card">
@@ -22,11 +20,11 @@
   <div class="definition-grid">
     <article>
       <strong>{label1}</strong>
-      <p>{def1 ?? `Definition pending for ${label1}.`}</p>
+      <p>{def1}</p>
     </article>
     <article>
       <strong>{label2}</strong>
-      <p>{def2 ?? `Definition pending for ${label2}.`}</p>
+      <p>{def2}</p>
     </article>
   </div>
 </section>

hdyc-svelte/src/lib/data/unitDefinitions.ts

@@ -100,6 +100,9 @@ const normalizeLabel = (label?: string): string | undefined => {
 const categoryPriority = [...Object.keys(domainDefinitions)];
 
 const specificDefinitions: Array<[RegExp, string]> = [
+  [/\btons? of tnt\b/i, 'measures explosive energy release. One ton of TNT is conventionally defined as 4.184 gigajoules of energy.'],
+  [/\batomic time units?\b/i, 'measures time on an atomic scale. One atomic unit of time is about 2.418884326505e-17 seconds.'],
+  [/\bastronomical units?\b/i, 'measures large distances in astronomy. One astronomical unit is the average Earth-Sun distance, exactly 149,597,870,700 meters.'],
   [/\bwatts?\b|\bkilowatts?\b|\bmegawatts?\b|\bhorsepower\b/i, 'measures the rate at which energy is transferred or converted. It is used for engines, appliances, electrical loads, and heat-transfer rates.'],
   [/\bcalories?\b|\bjoules?\b|\bbtu\b|\bkilocalories?\b|\btherms?\b|\bwatt hours?\b|\bkilowatt hours?\b/i, 'measures energy, heat, or work. These units are used for food energy, physics calculations, heating systems, and stored electricity.'],
   [/\bvolts?\b/i, 'measures electric potential difference. Voltage describes the electrical pressure that pushes current through a circuit.'],
@@ -177,3 +180,9 @@ export async function getDefinition(label: string, category?: string): Promise<s
   const entries = defs[normalized];
   return findByPriority(entries, category);
 }
+
+export function getDefinitionSync(label: string, category?: string): string | undefined {
+  const normalized = normalizeLabel(label);
+  if (!normalized) return undefined;
+  return buildDefinition(normalized, category || 'other');
+}

hdyc-svelte/src/routes/+page.ts

@@ -1,3 +1 @@
-// Prerender the homepage as static HTML at build time.
-// adapter-node will serve this as a static file — no SSR round-trip.
-export const prerender = true;
+export const prerender = false;

hdyc-svelte/src/routes/robots.txt/+server.ts

@@ -0,0 +1,16 @@
+import type { RequestHandler } from './$types';
+
+const robots = `User-agent: *
+Disallow:
+Sitemap: https://howdoyouconvert.com/sitemap.xml
+`;
+
+export const GET: RequestHandler = () =>
+	new Response(robots, {
+		headers: {
+			'Content-Type': 'text/plain; charset=utf-8',
+			'Cache-Control': 'no-cache, max-age=0, must-revalidate, no-transform',
+			'CDN-Cache-Control': 'max-age=300, stale-while-revalidate=86400',
+			'Cloudflare-CDN-Cache-Control': 'max-age=300, stale-while-revalidate=86400'
+		}
+	});

hdyc-svelte/src/routes/sitemap.xml/+server.ts

@@ -33,7 +33,9 @@ ${calculatorUrls.join('\n')}
 	return new Response(sitemap, {
 		headers: {
 			'Content-Type': 'application/xml',
-			'Cache-Control': 'max-age=0, s-maxage=3600'
+			'Cache-Control': 'no-cache, max-age=0, must-revalidate, no-transform',
+			'CDN-Cache-Control': 'max-age=300, stale-while-revalidate=86400',
+			'Cloudflare-CDN-Cache-Control': 'max-age=300, stale-while-revalidate=86400'
 		}
 	});
 };

hdyc-svelte/static/robots.txt

@@ -1,4 +0,0 @@
-# allow crawling everything by default
-User-agent: *
-Disallow:
-Sitemap: https://howdoyouconvert.com/sitemap.xml