chore: rename local header from cache-hit to x-proxy-cache and leave …

…it in the reply

src/routes/coingeckoProxy/index.ts

@@ -43,7 +43,10 @@ const coingeckoProxy: FastifyPluginAsync = async (
       if (isCachedResponse(result)) {
         fastify.log.info(`onRequest: cache hit for ${req.url}`);
         reply
-          .headers({ "cache-hit": true, ...result.item.headers })
+          .headers({
+            ...result.item.headers,
+            "x-proxy-cache": "HIT",
+          })
           .send(result.item.contents);
       }
     });
@@ -59,12 +62,16 @@ const coingeckoProxy: FastifyPluginAsync = async (
       );
     }
 
-    if (reply.getHeader("cache-hit")) {
-      // Header set when there's a cache hit, remove it
-      reply.removeHeader("cache-hit");
-    } else if (reply.statusCode >= 200 && reply.statusCode < 300) {
+    if (
+      reply.getHeader("x-proxy-cache") !== "HIT" &&
+      reply.statusCode >= 200 &&
+      reply.statusCode < 300
+    ) {
       fastify.log.info(`onSend: caching response for ${req.url}`);
 
+      // Set header indicating the internal cache miss
+      reply.header("x-proxy-cache", "MISS");
+
       // No cache hit, consume the payload stream to be able to cache it
       let contents = "";
       for await (const chunk of payload as ReadableStream) {