feat(compression): Improve compression implementation (buffering and threshold), add Deno brotli support, add compression tests and dynamic route API

ts/compression/compression.middleware.ts

@@ -68,7 +68,8 @@ export function normalizeCompressionConfig(
 // =============================================================================
 
 /**
- * Check if response should be compressed
+ * Check if response should be compressed (preliminary check)
+ * Note: Final threshold check happens in compressResponse after buffering
  */
 export function shouldCompressResponse(
   response: Response,
@@ -97,15 +98,6 @@ export function shouldCompressResponse(
     return false;
   }
 
-  // Check size threshold
-  const contentLength = response.headers.get('Content-Length');
-  if (contentLength) {
-    const size = parseInt(contentLength, 10);
-    if (size < (config.threshold ?? DEFAULT_COMPRESSION_CONFIG.threshold)) {
-      return false;
-    }
-  }
-
   // Check excluded paths
   if (config.exclude?.length) {
     const url = new URL(request.url);
@@ -166,28 +158,44 @@ export function selectCompressionAlgorithm(
 
 /**
  * Compress a Response object
+ * Uses buffered compression for reliability (streaming can have flushing issues)
  */
 export async function compressResponse(
   response: Response,
   algorithm: TCompressionAlgorithm,
-  level?: number
+  level?: number,
+  threshold?: number
 ): Promise<Response> {
   if (algorithm === 'identity' || !response.body) {
     return response;
   }
 
+  // Read the entire body first (required for proper compression)
+  const originalBody = new Uint8Array(await response.arrayBuffer());
+
+  // Check threshold - if body is too small, return uncompressed
+  const effectiveThreshold = threshold ?? DEFAULT_COMPRESSION_CONFIG.threshold;
+  if (originalBody.byteLength < effectiveThreshold) {
+    // Return original response with the body we read
+    return new Response(originalBody as unknown as BodyInit, {
+      status: response.status,
+      statusText: response.statusText,
+      headers: response.headers,
+    });
+  }
+
   const provider = getCompressionProvider();
 
+  // Compress the body
+  const compressedBody = await provider.compress(originalBody, algorithm, level);
+
   // Clone headers and modify
   const headers = new Headers(response.headers);
   headers.set('Content-Encoding', algorithm);
   headers.set('Vary', appendVaryHeader(headers.get('Vary'), 'Accept-Encoding'));
-  headers.delete('Content-Length'); // Size changes after compression
+  headers.set('Content-Length', compressedBody.byteLength.toString());
 
-  // Compress the body stream
-  const compressedBody = provider.compressStream(response.body, algorithm, level);
-
-  return new Response(compressedBody, {
+  return new Response(compressedBody as unknown as BodyInit, {
     status: response.status,
     statusText: response.statusText,
     headers,