20260416_2 并行优化phase1后进行snapshot fast path优化，通过四方面关键优化技术消除了验证主链路上snapshot构建是的db访问性能热点问题，性能热点转移到ROA验证处理本身，目前APNIC+ARIN全量同步从500秒压缩到212秒，离rpkclient 112秒差距变小

src/fetch/http.rs

@@ -392,6 +392,59 @@ mod tests {
         assert!(err.contains("http read body failed"), "{err}");
     }
 
+    #[test]
+    fn fetch_to_writer_streams_body_on_success() {
+        let url = spawn_one_shot_http_server("HTTP/1.1 200 OK", b"writer-body");
+        let http = BlockingHttpFetcher::new(HttpFetcherConfig {
+            timeout: Duration::from_secs(2),
+            ..HttpFetcherConfig::default()
+        })
+        .expect("http");
+        let mut out = Vec::new();
+        let bytes = http.fetch_to_writer(&url, &mut out).expect("stream");
+        assert_eq!(bytes, 11);
+        assert_eq!(out, b"writer-body");
+    }
+
+    #[test]
+    fn fetch_to_writer_rejects_non_success_status() {
+        let url = spawn_one_shot_http_server("HTTP/1.1 500 Internal Server Error", b"boom");
+        let http = BlockingHttpFetcher::new(HttpFetcherConfig {
+            timeout: Duration::from_secs(2),
+            ..HttpFetcherConfig::default()
+        })
+        .expect("http");
+        let mut out = Vec::new();
+        let err = http.fetch_to_writer(&url, &mut out).unwrap_err();
+        assert!(err.contains("http status"), "{err}");
+        assert!(out.is_empty());
+    }
+
+    #[test]
+    fn fetch_to_writer_times_out_on_idle_stream_read() {
+        let listener = TcpListener::bind(("127.0.0.1", 0)).expect("bind");
+        let addr = listener.local_addr().expect("addr");
+        thread::spawn(move || {
+            let (mut stream, _) = listener.accept().expect("accept");
+            let mut buf = [0u8; 1024];
+            let _ = stream.read(&mut buf);
+            stream
+                .write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 5\r\nConnection: close\r\n\r\nh")
+                .expect("write partial body");
+            std::thread::sleep(StdDuration::from_secs(2));
+            let _ = stream.write_all(b"ello");
+        });
+        let url = format!("http://{}/", addr);
+        let http = BlockingHttpFetcher::new(HttpFetcherConfig {
+            timeout: Duration::from_secs(1),
+            ..HttpFetcherConfig::default()
+        })
+        .expect("http");
+        let mut out = Vec::new();
+        let err = http.fetch_to_writer(&url, &mut out).unwrap_err();
+        assert!(err.contains("http stream body failed"), "{err}");
+    }
+
     #[test]
     fn uses_large_body_timeout_selects_rrdp_snapshot_and_delta_not_notification() {
         assert!(!uses_large_body_timeout(
@@ -407,4 +460,23 @@ mod tests {
             "https://tal.example.test/example.tal"
         ));
     }
+
+    #[test]
+    fn client_for_uri_selects_expected_timeout_profile() {
+        let http = BlockingHttpFetcher::new(HttpFetcherConfig {
+            timeout: Duration::from_secs(3),
+            large_body_timeout: Duration::from_secs(9),
+            ..HttpFetcherConfig::default()
+        })
+        .expect("http");
+
+        let (_, profile_short, timeout_short) = http.client_for_uri("https://example.test/root.tal");
+        assert_eq!(profile_short, "short");
+        assert_eq!(timeout_short, Duration::from_secs(3));
+
+        let (_, profile_large, timeout_large) =
+            http.client_for_uri("https://rrdp.example.test/session/1/snapshot.xml");
+        assert_eq!(profile_large, "large_body");
+        assert_eq!(timeout_large, Duration::from_secs(9));
+    }
 }