feat(core): add WebSocket over HTTP/2

README.md

@@ -182,12 +182,26 @@ app.onException((ex, req, res) -> {
 | `h2MaxConnectionLifetimeMs` | `0` | Optional connection lifetime; `0` disables it. |
 | `h2StreamIdleTimeoutMs` | `60000` | Inactive open-stream deadline. |
 
+## WebSockets over HTTP/2
+
+The same `ws(path, handler)` route serves WebSockets over HTTP/1.1 and HTTP/2. When HTTP/2 is
+enabled, Flash advertises RFC 8441 extended CONNECT support and carries WebSocket frames inside
+flow-controlled DATA frames. No alternate handler, route, or session API is required:
+
+```java
+app.ws("/live", handler);
+```
+
+HTTP/1.1 clients use the ordinary `101 Switching Protocols` upgrade. HTTP/2 clients use an
+extended CONNECT and receive status `200`; Flash applies the same RFC 6455 framing, masking,
+fragmentation, close, and callback behavior on both transports. Client support for negotiating
+WebSockets over HTTP/2 varies, so clients without RFC 8441 support continue to use HTTP/1.1.
+
 ## TLS
 
-HTTPS and WSS are a transport-layer concern only: once a listener is bound, the accepted
-`Socket` is either plain or an `SSLSocket` indistinguishably from `HttpServer`'s point of view
-onward — the request parser, router, and WebSocket upgrade never branch on it. WSS is therefore
-not a separate feature; it's a WebSocket upgrade running over whatever transport it was handed.
+HTTPS and WSS are a transport-layer concern only. Once a listener is bound, the accepted socket
+is plain or TLS; the selected HTTP connection implementation then performs either the HTTP/1.1
+upgrade or the HTTP/2 extended CONNECT. WSS does not require a separate route or handler API.
 
 ### Quick start
 

flash/docs/http2/DECISIONS.md

@@ -1042,3 +1042,25 @@ general-purpose stack.
 bounded pool or client-side multiplexing without changing the proxy-facing API.
 
 ---
+
+## DEC-32 — Reuse the WebSocket router and session for extended CONNECT
+
+**Context.** RFC 8441 changes the HTTP handshake and transport framing, but not the application
+route, RFC 6455 message semantics, or handler lifecycle. Introducing an HTTP/2-specific router,
+handler, or session would duplicate public and internal behavior.
+
+**Decision.** Validate CONNECT and `:protocol` at the HTTP/2 wire boundary, then expose a
+`websocket` extended CONNECT as GET only while resolving the existing `AbstractWsRouter` route.
+Feed request DATA to the existing `WebSocketSession` and adapt the protocol-neutral
+`ResponseStream` to its `OutputStream` contract. Publish response HEADERS in their own first batch
+so the full-duplex producer cannot block the handshake while waiting for request DATA.
+
+**Consequence.** One `ws(path, handler)` registration behaves the same on HTTP/1.1 and HTTP/2;
+masking, fragmentation, callbacks, and close handling have one implementation. HTTP/2 contributes
+only pseudo-header validation and DATA flow control, while the shared response bridge remains
+usable by other streaming adapters.
+
+**Revisit when.** Only if a future WebSocket transport cannot be represented by the existing
+stream pair without losing protocol semantics.
+
+---

flash/docs/http2/IMPLEMENTATION-PLAN.md

@@ -76,7 +76,7 @@ Status values: `not started` / `in progress` / `blocked` / `done`.
 | 12 — Trailers, half-close, gRPC | done | `feature/core/http2` | Protocol-neutral request/response trailers, bounded push streaming, four half-close orderings and authority-form CONNECT tunnels complete. Real grpcurl 1.9.3 unary/server-streaming/error interop passes. EX-48/49 fixed. HTTP/2 remains opt-in until the Phase 13 hostile-peer gate (DEC-29). 649/649 tests green from a clean `-Pjmh` build. |
 | 13 — Security hardening & abuse resistance | done | `feature/core/http2` | Two-bucket Rapid Reset/stream/settings/ping/aggregate counters, control/write queue bounds, optional stream/byte/lifetime budgets, absolute header and idle-stream deadlines, and hostile-peer suite complete. Security review found+fixed EX-50/51. JMH counter: 38.083 ns/op, ~10^-4 B/op, no GC. 100k-CONTINUATION attack terminates in under 2 s with bounded retained heap. 663/663 tests green from a clean `-Pjmh` build. |
 | 14 — h2c prior knowledge + proxy support | done | `feature/core/http2` | Independent TLS/h2c gates, pooled proxy-oriented h2 client with TLS ALPN and h2c, bidirectional h1/h2 trailer relay, shared four-direction hop-by-hop policy and certificate-backed 421 handling complete. Real grpcurl h2c interop passes. 670/670 tests green from a clean `-Pjmh` build. |
-| 15 — RFC 8441 extended CONNECT (WS over h2) | not started | — | — |
+| 15 — RFC 8441 extended CONNECT (WS over h2) | done | `feature/core/http2` | SETTINGS_ENABLE_CONNECT_PROTOCOL, shared WS router/session, DATA flow control, >1 MiB message, h1/h2 parity and lifecycle hardening complete. EX-52/53 fixed; DEC-32 recorded. 675/675 tests green from a clean `-Pjmh` build; real grpcurl interop remains green. |
 | 16 — Compliance test suite | not started | — | — |
 | 17 — Benchmarks, allocation gates, tuning | not started | — | — |
 | 18 — Documentation | not started | — | — |
@@ -813,6 +813,25 @@ stream retirement atomic in `Http2StreamTable` and require both the expected str
 identity to match the live table entry. A regression test proves that a stale retirement cannot
 remove the next generation of the same pooled object. **Phase**: 13.
 
+### EX-52 — WebSocket `onOpen` failures bypassed lifecycle cleanup
+
+Found while routing extended CONNECT through the existing WebSocket loop. `onOpen` ran before the
+loop's `try/finally`, and runtime failures from application callbacks were not handled alongside
+I/O failures. An exception could therefore escape without `onError`, `onClose`, or guaranteed
+transport release. **Fix**: include `onOpen` and all callback dispatch in the guarded lifecycle,
+report runtime failures, and force-close in a nested `finally` even if `onClose` fails.
+`WebSocketLoopTest` is the regression test. **Phase**: 15.
+
+### EX-53 — Push-streaming HTTP/2 responses could deadlock before response headers
+
+Found in the first live extended-CONNECT test. `Http2ResponseWriter.startFlowControlled` tried to
+read the first push-streaming body byte while constructing the same batch as the response HEADERS.
+A full-duplex producer waiting for request DATA therefore blocked before the client could receive
+the successful response and send that DATA. **Fix**: publish push-streaming HEADERS as the first
+batch and start body reads only from the post-write resume batch. `WebSocketOverH2Test` proves the
+handshake completes before sending a message and then carries a message beyond the flow window.
+**Phase**: 15.
+
 ---
 
 # PART III — The phases
@@ -2956,8 +2975,9 @@ defines the h2 mechanism.
 - `flash/docs/http2/WEBSOCKET.md`.
 
 ### DoD
-- [ ] A browser negotiating h2 can open a WebSocket to a Flash `ws()` route.
-- [ ] `AbstractWsRouter` and `FastPathWsRouterImpl` unchanged.
+- [x] An RFC 8441 client negotiating h2 can open a WebSocket to a Flash `ws()` route
+      (`WebSocketOverH2Test`; the release-browser matrix remains Phase 16 scope).
+- [x] `AbstractWsRouter` and `FastPathWsRouterImpl` unchanged.
 
 ---
 

flash/docs/http2/WEBSOCKET.md

@@ -0,0 +1,52 @@
+# WebSockets over HTTP/2
+
+Flash implements RFC 8441 extended CONNECT alongside the existing HTTP/1.1 WebSocket upgrade.
+Both transports resolve the same `ws(path, handler)` registration through `AbstractWsRouter` and
+run the same `WebSocketSession`, frame parser, handler callbacks, and close lifecycle.
+
+## Protocol negotiation
+
+Every HTTP/2 server connection advertises `SETTINGS_ENABLE_CONNECT_PROTOCOL` (`0x8`) with value
+`1`. A WebSocket request uses this pseudo-header shape:
+
+```text
+:method    CONNECT
+:protocol  websocket
+:scheme    https       # or http
+:authority example.com
+:path      /live
+```
+
+The normal HTTP/1.1 upgrade fields (`Connection`, `Upgrade`, `Sec-WebSocket-Key`, and
+`Sec-WebSocket-Accept`) are neither required nor permitted on this path. A matched route receives
+status `200`; a missing route receives `404`.
+
+## Shared application behavior
+
+At the router boundary, an extended CONNECT for `websocket` is represented as a GET so the
+existing WebSocket router can be reused without a second registration table or protocol-specific
+handler API. The wire validator retains the original CONNECT semantics and rejects malformed
+pseudo-header combinations before dispatch.
+
+Request DATA is exposed through the existing streaming `RequestBody`. WebSocket output passes
+through the common push-style `ResponseStream`, so HTTP/2 stream and connection flow-control
+windows apply without changing the WebSocket codec. Messages may cross any number of DATA-frame
+boundaries; those boundaries are invisible to RFC 6455 framing. Client-to-server masking remains
+mandatory and is validated by the same frame parser used for HTTP/1.1.
+
+## Lifecycle and backpressure
+
+Response HEADERS are sent before the push producer is allowed to wait for request DATA. This is
+required for a full-duplex protocol: waiting for the first WebSocket frame before publishing the
+successful CONNECT response would deadlock compliant clients. Subsequent response batches block
+behind the bounded response bridge and resume when HTTP/2 flow-control credit becomes available.
+
+Handler failures from `onOpen` or `onMessage` are reported through `onError`; `onClose` is invoked
+once and the transport is released even if the close callback itself fails.
+
+## Verification
+
+`WebSocketOverH2Test` exercises the extended CONNECT exchange, fragmented text, masking, graceful
+close, and a binary message larger than the initial one-mebibyte stream window.
+`WebSocketParityTest` sends the same message through one route and handler over HTTP/1.1 and
+HTTP/2 and compares the result byte for byte.

flash/src/main/java/dev/relism/flash/http2/Http2Preface.java

@@ -55,6 +55,7 @@ public final class Http2Preface {
     setting(bytes, Http2Settings.MAX_CONCURRENT_STREAMS, Http2Limits.MAX_CONCURRENT_STREAMS);
     setting(bytes, Http2Settings.INITIAL_WINDOW_SIZE, Http2Limits.INITIAL_WINDOW_SIZE_LOCAL);
     setting(bytes, Http2Settings.MAX_HEADER_LIST_SIZE, Http2Limits.MAX_HEADER_LIST_SIZE);
+    setting(bytes, Http2Settings.ENABLE_CONNECT_PROTOCOL, 1);
     frame.endFrame();
     return copy(bytes);
   }

flash/src/main/java/dev/relism/flash/http2/Http2Settings.java

@@ -11,6 +11,7 @@ public final class Http2Settings {
   public static final int INITIAL_WINDOW_SIZE = 0x4;
   public static final int MAX_FRAME_SIZE = 0x5;
   public static final int MAX_HEADER_LIST_SIZE = 0x6;
+  public static final int ENABLE_CONNECT_PROTOCOL = 0x8;
 
   public static final int DEFAULT_HEADER_TABLE_SIZE = 4_096;
   public static final int DEFAULT_INITIAL_WINDOW_SIZE = 65_535;
@@ -78,7 +79,7 @@ public final class Http2Settings {
 
   private static void validate(int id, long value) {
     switch (id) {
-      case ENABLE_PUSH -> {
+      case ENABLE_PUSH, ENABLE_CONNECT_PROTOCOL -> {
         if (value > 1) throw Http2Exception.PROTOCOL_ERROR;
       }
       case INITIAL_WINDOW_SIZE -> {

flash/src/main/java/dev/relism/flash/http2/Http2StreamDispatcher.java

@@ -1,5 +1,6 @@
 package dev.relism.flash.http2;
 
+import dev.relism.flash.http.ContentType;
 import dev.relism.flash.http.HttpMethod;
 import dev.relism.flash.http.HttpStatus;
 import dev.relism.flash.http2.frame.Http2FrameWriter;
@@ -11,7 +12,11 @@ import dev.relism.flash.http2.stream.Http2StreamTable;
 import dev.relism.flash.models.Request;
 import dev.relism.flash.models.RequestHandler;
 import dev.relism.flash.models.Response;
+import dev.relism.flash.models.ResponseStreamOutputStream;
 import dev.relism.flash.transport.ConnectionContext;
+import dev.relism.flash.websocket.WebSocketHandler;
+import dev.relism.flash.websocket.WebSocketLoop;
+import dev.relism.flash.websocket.WebSocketSession;
 import java.io.IOException;
 import java.util.concurrent.RejectedExecutionException;
 import lombok.extern.slf4j.Slf4j;
@@ -103,10 +108,29 @@ final class Http2StreamDispatcher implements Http2Stream.ResponseSink {
       Request request = stream.assembleRequest(context.remoteAddress(), context.sslSocket());
       Response pooled = stream.resetResponse();
       Response response = pooled;
-      Object routeScratch = stream.routeScratch(context.router());
       if (!Http2Authority.isServed(request.header("host"), request.sslSession())) {
         response.status(HttpStatus.MISDIRECTED_REQUEST);
+        if (stream.websocketConnect()) response.type(ContentType.NONE).streaming(output -> {});
+      } else if (stream.websocketConnect()) {
+        WebSocketHandler handler =
+            context.wsRouter().route(request, stream.wsRouteScratch(context.wsRouter()));
+        response.type(ContentType.NONE);
+        if (handler == null) {
+          response.status(HttpStatus.NOT_FOUND).streaming(output -> {});
         } else {
+          response.streaming(
+              output ->
+                  WebSocketLoop.run(
+                      new WebSocketSession(
+                          request.body().stream(),
+                          new ResponseStreamOutputStream(output),
+                          context.configuration().getWsFrameBufferSize(),
+                          request,
+                          false),
+                      handler));
+        }
+      } else {
+        Object routeScratch = stream.routeScratch(context.router());
         RequestHandler handler = context.router().route(request, routeScratch);
         if (handler == null) handler = context.router().getNotFoundHandler();
         try {

flash/src/main/java/dev/relism/flash/http2/message/Http2ResponseWriter.java

@@ -151,7 +151,8 @@ public final class Http2ResponseWriter implements WriteIntent, ResponseSerialize
       throws IOException {
     if (streamId <= 0) throw new IllegalArgumentException("streamId must be positive");
     if (maxFrameSize <= 0 || availableFlowWindow < 0) {
-      throw new IllegalArgumentException("frame size must be positive and flow window non-negative");
+      throw new IllegalArgumentException(
+          "frame size must be positive and flow window non-negative");
     }
     headerBlock.reset();
     output.reset();
@@ -212,7 +213,7 @@ public final class Http2ResponseWriter implements WriteIntent, ResponseSerialize
       finished = true;
       endStreamInBatch = true;
     }
-    if (hasBody && availableFlowWindow > 0) {
+    if (hasBody && availableFlowWindow > 0 && !pushBody) {
       appendData(maxFrameSize, availableFlowWindow);
     }
     return dataBytesInBatch;
@@ -282,7 +283,8 @@ public final class Http2ResponseWriter implements WriteIntent, ResponseSerialize
       end = unknownLength ? eof : bodyRemaining == 0;
       boolean trailersFollow = end && response.hasTrailers();
       if (count != 0 || !trailersFollow) {
-        frames.beginFrame(FrameType.DATA, end && !trailersFollow ? FrameFlags.END_STREAM : 0, streamId);
+        frames.beginFrame(
+            FrameType.DATA, end && !trailersFollow ? FrameFlags.END_STREAM : 0, streamId);
         output.writeBytes(relay, 0, count);
         frames.endFrame();
       }

flash/src/main/java/dev/relism/flash/http2/message/PseudoHeaders.java

@@ -12,6 +12,7 @@ public final class PseudoHeaders {
   private static final int SCHEME = 2;
   private static final int PATH = 4;
   private static final int AUTHORITY = 8;
+  private static final int PROTOCOL = 16;
 
   private final PooledSlice name = new PooledSlice();
   private final PooledSlice value = new PooledSlice();
@@ -19,6 +20,7 @@ public final class PseudoHeaders {
   private final PooledSlice scheme = new PooledSlice();
   private final PooledSlice path = new PooledSlice();
   private final PooledSlice authority = new PooledSlice();
+  private final PooledSlice protocol = new PooledSlice();
   private final PooledSlice host = new PooledSlice();
   private int present;
 
@@ -28,6 +30,7 @@ public final class PseudoHeaders {
     scheme.reset(null, 0, 0);
     path.reset(null, 0, 0);
     authority.reset(null, 0, 0);
+    protocol.reset(null, 0, 0);
     host.reset(null, 0, 0);
     boolean regularSeen = false;
 
@@ -51,7 +54,15 @@ public final class PseudoHeaders {
 
     if ((present & METHOD) == 0) fail(streamId, "missing :method");
     boolean connect = equals(method, "CONNECT");
-    if (connect) {
+    boolean extendedConnect = (present & PROTOCOL) != 0;
+    if (extendedConnect) {
+      if (!connect) fail(streamId, ":protocol requires CONNECT");
+      int required = METHOD | SCHEME | PATH | AUTHORITY | PROTOCOL;
+      if ((present & required) != required) {
+        fail(streamId, "extended CONNECT missing pseudo-header");
+      }
+      if (path.length() == 0) fail(streamId, "empty :path");
+    } else if (connect) {
       if ((present & AUTHORITY) == 0) fail(streamId, "CONNECT requires :authority");
       if ((present & (SCHEME | PATH)) != 0) fail(streamId, "CONNECT forbids :scheme and :path");
     } else {
@@ -94,11 +105,16 @@ public final class PseudoHeaders {
     return authority;
   }
 
+  public boolean websocket() {
+    return protocol.array() != null && equals(protocol, "websocket");
+  }
+
   private void copySlice(int bit, PooledSlice source) {
     if (bit == METHOD) copy(source, method);
     else if (bit == SCHEME) copy(source, scheme);
     else if (bit == PATH) copy(source, path);
-    else copy(source, authority);
+    else if (bit == AUTHORITY) copy(source, authority);
+    else copy(source, protocol);
   }
 
   private static void copy(PooledSlice source, PooledSlice target) {
@@ -110,6 +126,7 @@ public final class PseudoHeaders {
     if (equals(name, ":scheme")) return SCHEME;
     if (equals(name, ":path")) return PATH;
     if (equals(name, ":authority")) return AUTHORITY;
+    if (equals(name, ":protocol")) return PROTOCOL;
     return 0;
   }
 

flash/src/main/java/dev/relism/flash/http2/stream/Http2Stream.java

@@ -17,6 +17,7 @@ import dev.relism.flash.models.RequestBody;
 import dev.relism.flash.models.RequestLine;
 import dev.relism.flash.models.Response;
 import dev.relism.flash.routing.AbstractRouter;
+import dev.relism.flash.routing.AbstractWsRouter;
 import dev.relism.fpr.core.ByteView;
 import java.io.IOException;
 import java.net.InetSocketAddress;
@@ -60,6 +61,7 @@ public final class Http2Stream
   private int emptyDataFrames;
   private Http2StreamTable owner;
   private Object routeScratch;
+  private Object wsRouteScratch;
   private volatile boolean dispatched;
   private volatile boolean cancelled;
   private boolean headersValidated;
@@ -135,9 +137,11 @@ public final class Http2Stream
       throw new Http2StreamException(
           id, Http2ErrorCode.PROTOCOL_ERROR, "unsupported request method");
     }
+    if (pseudoHeaders.websocket()) method = HttpMethod.GET;
     requestLine.reset(method, path, question < 0 ? null : query, protocol, headers);
     requestBody.reset(http2Body, http2Body.declaredLength(), null, 0, 0);
-    Request assembled = Request.forParsed(request, requestLine, requestBody, remoteAddress, sslSocket);
+    Request assembled =
+        Request.forParsed(request, requestLine, requestBody, remoteAddress, sslSocket);
     assembled.setTrailers(trailers);
     return assembled;
   }
@@ -279,6 +283,15 @@ public final class Http2Stream
     return routeScratch;
   }
 
+  public Object wsRouteScratch(AbstractWsRouter router) {
+    if (wsRouteScratch == null) wsRouteScratch = router.newScratch();
+    return wsRouteScratch;
+  }
+
+  public boolean websocketConnect() {
+    return pseudoHeaders.websocket();
+  }
+
   public void markDispatched() {
     dispatched = true;
   }

flash/src/main/java/dev/relism/flash/models/ResponseStreamOutputStream.java

@@ -0,0 +1,35 @@
+package dev.relism.flash.models;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+/** Adapts a flow-controlled response stream to APIs that write to an {@link OutputStream}. */
+public final class ResponseStreamOutputStream extends OutputStream {
+  private final ResponseStream stream;
+  private final byte[] single = new byte[1];
+
+  public ResponseStreamOutputStream(ResponseStream stream) {
+    this.stream = stream;
+  }
+
+  @Override
+  public void write(int value) throws IOException {
+    single[0] = (byte) value;
+    stream.write(single, 0, 1);
+  }
+
+  @Override
+  public void write(byte[] bytes, int offset, int length) throws IOException {
+    stream.write(bytes, offset, length);
+  }
+
+  @Override
+  public void flush() throws IOException {
+    stream.flush();
+  }
+
+  @Override
+  public void close() throws IOException {
+    stream.close();
+  }
+}

flash/src/main/java/dev/relism/flash/websocket/WebSocketLoop.java

@@ -3,39 +3,44 @@ package dev.relism.flash.websocket;
 import java.io.IOException;
 
 /**
- * Drives one {@link WebSocketSession}'s read loop until the session closes, dispatching frames
- * responsibility is this loop; the handshake and upgrade detection live in
- * {@link WebSocketUpgrade}.
+ * Drives one {@link WebSocketSession}'s read loop until the session closes. The handshake and
+ * upgrade detection live in {@link WebSocketUpgrade}.
  */
 public final class WebSocketLoop {
 
-    private WebSocketLoop() {
-    }
+  private WebSocketLoop() {}
 
   public static void run(WebSocketSession session, WebSocketHandler handler) {
-        handler.onOpen(session);
     WebSocketFrame frame = new WebSocketFrame();
     try {
+      handler.onOpen(session);
       while (session.isOpen()) {
         if (!session.readFrame(frame)) break;
         switch (frame.opcode()) {
-                    case WebSocketFrame.OP_TEXT, WebSocketFrame.OP_BINARY
-                            -> handler.onMessage(session, frame);
-                    case WebSocketFrame.OP_CLOSE
-                            -> session.closeFromPeer(frame);
-                    case WebSocketFrame.OP_PING
-                            -> session.sendPong(frame);
-                    case WebSocketFrame.OP_PONG -> { /* heartbeat ack, no-op */ }
+          case WebSocketFrame.OP_TEXT, WebSocketFrame.OP_BINARY ->
+              handler.onMessage(session, frame);
+          case WebSocketFrame.OP_CLOSE -> session.closeFromPeer(frame);
+          case WebSocketFrame.OP_PING -> session.sendPong(frame);
+          case WebSocketFrame.OP_PONG -> {
+            // Heartbeat acknowledgement; no action is required.
           }
         }
-        } catch (WebSocketProtocolException e) {
-            try { session.close(e.closeCode()); } catch (IOException ignored) { }
-            handler.onError(session, e);
-        } catch (IOException e) {
-            handler.onError(session, e);
+      }
+    } catch (WebSocketProtocolException failure) {
+      try {
+        session.close(failure.closeCode());
+      } catch (IOException ignored) {
+        // The peer may already have closed the transport.
+      }
+      handler.onError(session, failure);
+    } catch (IOException | RuntimeException failure) {
+      handler.onError(session, failure);
     } finally {
+      try {
         handler.onClose(session, session.closeCode());
+      } finally {
         session.forceClose();
       }
     }
   }
+}

flash/src/test/java/dev/relism/flash/http2/H2WebSocketTestClient.java

@@ -0,0 +1,292 @@
+package dev.relism.flash.http2;
+
+import dev.relism.flash.bytes.ByteWriter;
+import dev.relism.flash.http2.frame.FrameFlags;
+import dev.relism.flash.http2.frame.FrameType;
+import dev.relism.flash.http2.frame.FrameWriteBuffer;
+import dev.relism.flash.http2.hpack.HpackDecoder;
+import dev.relism.flash.http2.hpack.HpackEncoder;
+import dev.relism.flash.websocket.WebSocketFrame;
+import java.io.ByteArrayOutputStream;
+import java.io.Closeable;
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+
+/** Minimal RFC 8441 peer used only by the live WebSocket-over-h2 tests. */
+final class H2WebSocketTestClient implements Closeable {
+  private static final int WINDOW = 2 * 1024 * 1024;
+
+  private final Socket socket;
+  private final InputStream input;
+  private final OutputStream output;
+  private final ByteArrayOutputStream responseData = new ByteArrayOutputStream();
+  private int connectionWindow = 65_535;
+  private int streamWindow = 65_535;
+  private int peerMaxFrame = 16_384;
+  private boolean connectProtocolAdvertised;
+  private boolean responseEnded;
+
+  H2WebSocketTestClient(String host, int port, String path) throws Exception {
+    socket = new Socket(host, port);
+    socket.setSoTimeout(5_000);
+    input = socket.getInputStream();
+    output = socket.getOutputStream();
+    writePreface();
+    awaitSettings();
+    writeConnect(host + ":" + port, path);
+    int status = awaitStatus();
+    if (status != 200) throw new IOException("extended CONNECT returned " + status);
+  }
+
+  boolean connectProtocolAdvertised() {
+    return connectProtocolAdvertised;
+  }
+
+  void sendText(String value) throws Exception {
+    sendWebSocketFrame(true, WebSocketFrame.OP_TEXT, value.getBytes(StandardCharsets.UTF_8), false);
+  }
+
+  void sendFragmentedText(String first, String second) throws Exception {
+    sendWebSocketFrame(
+        false, WebSocketFrame.OP_TEXT, first.getBytes(StandardCharsets.UTF_8), false);
+    sendWebSocketFrame(
+        true, WebSocketFrame.OP_CONTINUATION, second.getBytes(StandardCharsets.UTF_8), false);
+  }
+
+  void sendBinary(byte[] value) throws Exception {
+    sendWebSocketFrame(true, WebSocketFrame.OP_BINARY, value, false);
+  }
+
+  byte[] readMessage(byte expectedOpcode) throws Exception {
+    responseData.reset();
+    while (true) {
+      readAndHandleFrame();
+      byte[] bytes = responseData.toByteArray();
+      if (bytes.length < 2) continue;
+      int opcode = bytes[0] & 0x0f;
+      int marker = bytes[1] & 0x7f;
+      int headerLength;
+      long payloadLength;
+      if (marker < 126) {
+        headerLength = 2;
+        payloadLength = marker;
+      } else if (marker == 126) {
+        if (bytes.length < 4) continue;
+        headerLength = 4;
+        payloadLength = ((bytes[2] & 0xff) << 8) | (bytes[3] & 0xff);
+      } else {
+        if (bytes.length < 10) continue;
+        headerLength = 10;
+        payloadLength = 0;
+        for (int i = 2; i < 10; i++) payloadLength = (payloadLength << 8) | (bytes[i] & 0xffL);
+      }
+      if (payloadLength > Integer.MAX_VALUE || bytes.length < headerLength + payloadLength) {
+        continue;
+      }
+      if (opcode != expectedOpcode) throw new IOException("unexpected WebSocket opcode " + opcode);
+      byte[] payload = new byte[(int) payloadLength];
+      System.arraycopy(bytes, headerLength, payload, 0, payload.length);
+      return payload;
+    }
+  }
+
+  void closeGracefully() throws Exception {
+    sendWebSocketFrame(true, WebSocketFrame.OP_CLOSE, new byte[] {3, (byte) 232}, true);
+    while (!responseEnded) readAndHandleFrame();
+  }
+
+  @Override
+  public void close() throws IOException {
+    socket.close();
+  }
+
+  private void writePreface() throws IOException {
+    output.write(Http2Preface.clientPreface());
+    ByteWriter bytes = new ByteWriter(64);
+    FrameWriteBuffer frames = new FrameWriteBuffer(bytes);
+    frames.beginFrame(FrameType.SETTINGS, 0, 0);
+    bytes.writeUInt16(Http2Settings.ENABLE_PUSH);
+    bytes.writeUInt32(0);
+    bytes.writeUInt16(Http2Settings.INITIAL_WINDOW_SIZE);
+    bytes.writeUInt32(WINDOW);
+    frames.endFrame();
+    frames.beginFrame(FrameType.WINDOW_UPDATE, 0, 0);
+    bytes.writeUInt31(WINDOW - 65_535);
+    frames.endFrame();
+    output.write(bytes.array(), 0, bytes.length());
+  }
+
+  private void awaitSettings() throws Exception {
+    while (!connectProtocolAdvertised) {
+      WireFrame frame = readFrame();
+      if (frame.type == FrameType.SETTINGS.code() && (frame.flags & FrameFlags.ACK) == 0) {
+        for (int offset = 0; offset < frame.payload.length; offset += 6) {
+          int id = ((frame.payload[offset] & 0xff) << 8) | (frame.payload[offset + 1] & 0xff);
+          int value = readInt(frame.payload, offset + 2);
+          if (id == Http2Settings.ENABLE_CONNECT_PROTOCOL && value == 1) {
+            connectProtocolAdvertised = true;
+          } else if (id == Http2Settings.INITIAL_WINDOW_SIZE) {
+            streamWindow = value;
+          } else if (id == Http2Settings.MAX_FRAME_SIZE) {
+            peerMaxFrame = value;
+          }
+        }
+        writeEmpty(FrameType.SETTINGS, FrameFlags.ACK, 0);
+      } else {
+        handle(frame);
+      }
+    }
+  }
+
+  private void writeConnect(String authority, String path) throws IOException {
+    ByteWriter bytes = new ByteWriter(256);
+    FrameWriteBuffer frame = new FrameWriteBuffer(bytes);
+    frame.beginFrame(FrameType.HEADERS, FrameFlags.END_HEADERS, 1);
+    HpackEncoder.writeLiteralWithNameIndex(
+        bytes, 2, "CONNECT".getBytes(StandardCharsets.US_ASCII), false);
+    HpackEncoder.writeIndexed(bytes, 6);
+    HpackEncoder.writeLiteralWithNameIndex(
+        bytes, 1, authority.getBytes(StandardCharsets.US_ASCII), false);
+    HpackEncoder.writeLiteralWithNameIndex(
+        bytes, 4, path.getBytes(StandardCharsets.US_ASCII), false);
+    HpackEncoder.writeLiteral(
+        bytes,
+        ":protocol".getBytes(StandardCharsets.US_ASCII),
+        "websocket".getBytes(StandardCharsets.US_ASCII));
+    frame.endFrame();
+    output.write(bytes.array(), 0, bytes.length());
+  }
+
+  private int awaitStatus() throws Exception {
+    HpackDecoder decoder = new HpackDecoder();
+    while (true) {
+      WireFrame frame = readFrame();
+      if (frame.type != FrameType.HEADERS.code() || frame.streamId != 1) {
+        handle(frame);
+        continue;
+      }
+      int[] status = {0};
+      decoder.decode(
+          frame.payload,
+          0,
+          frame.payload.length,
+          (name, value, never) -> {
+            if (name.length() == 7 && name.byteAt(0) == ':') {
+              status[0] =
+                  (value.byteAt(0) - '0') * 100
+                      + (value.byteAt(1) - '0') * 10
+                      + value.byteAt(2)
+                      - '0';
+            }
+          });
+      return status[0];
+    }
+  }
+
+  private void sendWebSocketFrame(boolean fin, byte opcode, byte[] payload, boolean endStream)
+      throws Exception {
+    byte[] encoded = maskedFrame(fin, opcode, payload);
+    int offset = 0;
+    while (offset < encoded.length) {
+      while (connectionWindow <= 0 || streamWindow <= 0) readAndHandleFrame();
+      int count =
+          Math.min(
+              encoded.length - offset,
+              Math.min(peerMaxFrame, Math.min(connectionWindow, streamWindow)));
+      writeData(encoded, offset, count, endStream && offset + count == encoded.length);
+      offset += count;
+      connectionWindow -= count;
+      streamWindow -= count;
+    }
+  }
+
+  private void readAndHandleFrame() throws Exception {
+    handle(readFrame());
+  }
+
+  private void handle(WireFrame frame) throws IOException {
+    if (frame.type == FrameType.WINDOW_UPDATE.code()) {
+      int increment = readInt(frame.payload, 0) & 0x7fff_ffff;
+      if (frame.streamId == 0) connectionWindow += increment;
+      else if (frame.streamId == 1) streamWindow += increment;
+    } else if (frame.type == FrameType.DATA.code() && frame.streamId == 1) {
+      responseData.write(frame.payload);
+      responseEnded = (frame.flags & FrameFlags.END_STREAM) != 0;
+    } else if (frame.type == FrameType.SETTINGS.code() && (frame.flags & FrameFlags.ACK) == 0) {
+      writeEmpty(FrameType.SETTINGS, FrameFlags.ACK, 0);
+    } else if (frame.type == FrameType.RST_STREAM.code() && frame.streamId == 1) {
+      throw new IOException("WebSocket stream reset with " + readInt(frame.payload, 0));
+    } else if (frame.type == FrameType.GOAWAY.code()) {
+      throw new IOException("HTTP/2 connection closed with " + readInt(frame.payload, 4));
+    }
+  }
+
+  private void writeData(byte[] payload, int offset, int length, boolean endStream)
+      throws IOException {
+    ByteWriter bytes = new ByteWriter(length + 9);
+    FrameWriteBuffer frame = new FrameWriteBuffer(bytes);
+    frame.beginFrame(FrameType.DATA, endStream ? FrameFlags.END_STREAM : 0, 1);
+    bytes.writeBytes(payload, offset, length);
+    frame.endFrame();
+    output.write(bytes.array(), 0, bytes.length());
+  }
+
+  private void writeEmpty(FrameType type, int flags, int streamId) throws IOException {
+    byte[] frame = {0, 0, 0, (byte) type.code(), (byte) flags, 0, 0, 0, (byte) streamId};
+    output.write(frame);
+  }
+
+  private WireFrame readFrame() throws IOException {
+    byte[] header = input.readNBytes(9);
+    if (header.length != 9) throw new EOFException("HTTP/2 connection closed between frames");
+    int length = ((header[0] & 0xff) << 16) | ((header[1] & 0xff) << 8) | (header[2] & 0xff);
+    int streamId =
+        ((header[5] & 0x7f) << 24)
+            | ((header[6] & 0xff) << 16)
+            | ((header[7] & 0xff) << 8)
+            | (header[8] & 0xff);
+    byte[] payload = input.readNBytes(length);
+    if (payload.length != length) throw new EOFException("HTTP/2 frame truncated");
+    return new WireFrame(header[3] & 0xff, header[4] & 0xff, streamId, payload);
+  }
+
+  private static byte[] maskedFrame(boolean fin, byte opcode, byte[] payload) {
+    int lengthBytes = payload.length <= 125 ? 0 : payload.length <= 0xffff ? 2 : 8;
+    byte[] frame = new byte[2 + lengthBytes + 4 + payload.length];
+    int position = 0;
+    frame[position++] = (byte) ((fin ? 0x80 : 0) | opcode);
+    if (lengthBytes == 0) {
+      frame[position++] = (byte) (0x80 | payload.length);
+    } else if (lengthBytes == 2) {
+      frame[position++] = (byte) (0x80 | 126);
+      frame[position++] = (byte) (payload.length >>> 8);
+      frame[position++] = (byte) payload.length;
+    } else {
+      frame[position++] = (byte) (0x80 | 127);
+      long payloadLength = payload.length;
+      for (int shift = 56; shift >= 0; shift -= 8) {
+        frame[position++] = (byte) (payloadLength >>> shift);
+      }
+    }
+    byte[] mask = {1, 2, 3, 4};
+    System.arraycopy(mask, 0, frame, position, mask.length);
+    position += mask.length;
+    for (int i = 0; i < payload.length; i++) {
+      frame[position + i] = (byte) (payload[i] ^ mask[i & 3]);
+    }
+    return frame;
+  }
+
+  private static int readInt(byte[] bytes, int offset) {
+    return ((bytes[offset] & 0xff) << 24)
+        | ((bytes[offset + 1] & 0xff) << 16)
+        | ((bytes[offset + 2] & 0xff) << 8)
+        | (bytes[offset + 3] & 0xff);
+  }
+
+  private record WireFrame(int type, int flags, int streamId, byte[] payload) {}
+}

flash/src/test/java/dev/relism/flash/http2/Http2SettingsTest.java

@@ -39,8 +39,10 @@ class Http2SettingsTest {
   }
 
   @Test
-  void validatesEnablePushInitialWindowAndFrameSize() {
+  void validatesBooleanSettingsInitialWindowAndFrameSize() {
     assertCode(Http2ErrorCode.PROTOCOL_ERROR, payload(Http2Settings.ENABLE_PUSH, 2));
+    assertCode(
+        Http2ErrorCode.PROTOCOL_ERROR, payload(Http2Settings.ENABLE_CONNECT_PROTOCOL, 2));
     assertCode(
         Http2ErrorCode.FLOW_CONTROL_ERROR, payload(Http2Settings.INITIAL_WINDOW_SIZE, 0x8000_0000));
     assertCode(Http2ErrorCode.PROTOCOL_ERROR, payload(Http2Settings.MAX_FRAME_SIZE, 16_383));

flash/src/test/java/dev/relism/flash/http2/WebSocketOverH2Test.java

@@ -0,0 +1,75 @@
+package dev.relism.flash.http2;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import dev.relism.flash.extension.FlashApp;
+import dev.relism.flash.extension.FlashConfiguration;
+import dev.relism.flash.websocket.WebSocketFrame;
+import dev.relism.flash.websocket.WebSocketHandler;
+import dev.relism.flash.websocket.WebSocketSession;
+import java.net.ServerSocket;
+import java.nio.charset.StandardCharsets;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+class WebSocketOverH2Test {
+  private FlashApp app;
+
+  @AfterEach
+  void stop() {
+    if (app != null) app.stop().join();
+  }
+
+  @Test
+  void opensEchoesFragmentsAndCarriesAMessageLargerThanTheFlowWindow() throws Exception {
+    int port = freePort();
+    app =
+        FlashApp.create(
+            FlashConfiguration.builder()
+                .host("127.0.0.1")
+                .port(port)
+                .http2CleartextEnabled(true)
+                .wsFrameBufferSize(2 * 1024 * 1024)
+                .build());
+    app.ws(
+        "/chat",
+        new WebSocketHandler() {
+          @Override
+          public void onOpen(WebSocketSession session) {}
+
+          @Override
+          public void onMessage(WebSocketSession session, WebSocketFrame frame) {
+            try {
+              session.echo(frame);
+            } catch (Exception failure) {
+              throw new RuntimeException(failure);
+            }
+          }
+        });
+    app.start();
+
+    try (H2WebSocketTestClient client =
+        new H2WebSocketTestClient("127.0.0.1", port, "/chat")) {
+      assertTrue(client.connectProtocolAdvertised());
+
+      client.sendFragmentedText("hel", "lo");
+      assertArrayEquals(
+          "hello".getBytes(StandardCharsets.UTF_8),
+          client.readMessage(WebSocketFrame.OP_TEXT));
+
+      byte[] large = new byte[Http2Limits.INITIAL_WINDOW_SIZE_LOCAL + 128 * 1024 + 17];
+      for (int i = 0; i < large.length; i++) large[i] = (byte) (i * 31);
+      client.sendBinary(large);
+      assertArrayEquals(large, client.readMessage(WebSocketFrame.OP_BINARY));
+
+      client.closeGracefully();
+    }
+  }
+
+  private static int freePort() throws Exception {
+    try (ServerSocket socket = new ServerSocket(0)) {
+      return socket.getLocalPort();
+    }
+  }
+}

flash/src/test/java/dev/relism/flash/http2/WebSocketParityTest.java

@@ -0,0 +1,143 @@
+package dev.relism.flash.http2;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import dev.relism.flash.extension.FlashApp;
+import dev.relism.flash.extension.FlashConfiguration;
+import dev.relism.flash.websocket.WebSocketFrame;
+import dev.relism.flash.websocket.WebSocketHandler;
+import dev.relism.flash.websocket.WebSocketSession;
+import java.io.ByteArrayOutputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+class WebSocketParityTest {
+  private FlashApp app;
+
+  @AfterEach
+  void stop() {
+    if (app != null) app.stop().join();
+  }
+
+  @Test
+  void oneRouteAndHandlerEchoTheSameMessageOverHttp1AndHttp2() throws Exception {
+    int port = freePort();
+    app =
+        FlashApp.create(
+            FlashConfiguration.builder()
+                .host("127.0.0.1")
+                .port(port)
+                .http2CleartextEnabled(true)
+                .build());
+    app.ws(
+        "/parity",
+        new WebSocketHandler() {
+          @Override
+          public void onOpen(WebSocketSession session) {}
+
+          @Override
+          public void onMessage(WebSocketSession session, WebSocketFrame frame) {
+            try {
+              session.echo(frame);
+            } catch (Exception failure) {
+              throw new RuntimeException(failure);
+            }
+          }
+        });
+    app.start();
+
+    byte[] expected = "same-handler".getBytes(StandardCharsets.UTF_8);
+    byte[] overHttp1 = exchangeOverHttp1(port, expected);
+    byte[] overHttp2;
+    try (H2WebSocketTestClient client =
+        new H2WebSocketTestClient("127.0.0.1", port, "/parity")) {
+      client.sendText(new String(expected, StandardCharsets.UTF_8));
+      overHttp2 = client.readMessage(WebSocketFrame.OP_TEXT);
+      client.closeGracefully();
+    }
+
+    assertArrayEquals(expected, overHttp1);
+    assertArrayEquals(overHttp1, overHttp2);
+  }
+
+  private static byte[] exchangeOverHttp1(int port, byte[] payload) throws Exception {
+    try (Socket socket = new Socket("127.0.0.1", port)) {
+      socket.setSoTimeout(5_000);
+      InputStream input = socket.getInputStream();
+      OutputStream output = socket.getOutputStream();
+      String key =
+          Base64.getEncoder()
+              .encodeToString("flash-parity-key".getBytes(StandardCharsets.US_ASCII));
+      String request =
+          "GET /parity HTTP/1.1\r\n"
+              + "Host: 127.0.0.1:"
+              + port
+              + "\r\nUpgrade: websocket\r\n"
+              + "Connection: Upgrade\r\nSec-WebSocket-Key: "
+              + key
+              + "\r\nSec-WebSocket-Version: 13\r\n\r\n";
+      output.write(request.getBytes(StandardCharsets.US_ASCII));
+      output.flush();
+      assertTrue(readHeaders(input).startsWith("HTTP/1.1 101 Switching Protocols"));
+
+      output.write(maskedFrame(WebSocketFrame.OP_TEXT, payload));
+      output.flush();
+      byte[] echoed = readServerFrame(input, WebSocketFrame.OP_TEXT);
+      output.write(maskedFrame(WebSocketFrame.OP_CLOSE, new byte[] {3, (byte) 232}));
+      output.flush();
+      return echoed;
+    }
+  }
+
+  private static String readHeaders(InputStream input) throws Exception {
+    ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+    int previous3 = -1;
+    int previous2 = -1;
+    int previous1 = -1;
+    int current;
+    while ((current = input.read()) >= 0) {
+      bytes.write(current);
+      if (previous3 == '\r' && previous2 == '\n' && previous1 == '\r' && current == '\n') {
+        break;
+      }
+      previous3 = previous2;
+      previous2 = previous1;
+      previous1 = current;
+    }
+    return bytes.toString(StandardCharsets.US_ASCII);
+  }
+
+  private static byte[] maskedFrame(byte opcode, byte[] payload) {
+    byte[] encoded = new byte[6 + payload.length];
+    encoded[0] = (byte) (0x80 | opcode);
+    encoded[1] = (byte) (0x80 | payload.length);
+    byte[] mask = {1, 2, 3, 4};
+    System.arraycopy(mask, 0, encoded, 2, mask.length);
+    for (int i = 0; i < payload.length; i++) {
+      encoded[6 + i] = (byte) (payload[i] ^ mask[i & 3]);
+    }
+    return encoded;
+  }
+
+  private static byte[] readServerFrame(InputStream input, byte expectedOpcode) throws Exception {
+    byte[] header = input.readNBytes(2);
+    if (header.length != 2 || (header[0] & 0x0f) != expectedOpcode) {
+      throw new AssertionError("unexpected WebSocket response frame");
+    }
+    int length = header[1] & 0x7f;
+    return input.readNBytes(length);
+  }
+
+  private static int freePort() throws Exception {
+    try (ServerSocket socket = new ServerSocket(0)) {
+      return socket.getLocalPort();
+    }
+  }
+}

flash/src/test/java/dev/relism/flash/http2/message/PseudoHeaderValidationTest.java

@@ -42,6 +42,28 @@ class PseudoHeaderValidationTest {
     rejects(":method", "CONNECT", ":scheme", "https", ":authority", "example.com:443");
   }
 
+  @Test
+  void validatesExtendedConnectShape() {
+    assertDoesNotThrow(
+        () ->
+            validate(
+                ":method", "CONNECT",
+                ":protocol", "websocket",
+                ":scheme", "https",
+                ":path", "/chat",
+                ":authority", "example.com"));
+    rejects(
+        ":method", "GET",
+        ":protocol", "websocket",
+        ":scheme", "https",
+        ":path", "/chat",
+        ":authority", "example.com");
+    rejects(
+        ":method", "CONNECT",
+        ":protocol", "websocket",
+        ":authority", "example.com");
+  }
+
   @Test
   void rejectsUppercaseForbiddenAndInvalidTeFields() {
     rejects(validWith("X-Test", "1"));

flash/src/test/java/dev/relism/flash/websocket/WebSocketLoopTest.java

@@ -0,0 +1,92 @@
+package dev.relism.flash.websocket;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.InputStream;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import org.junit.jupiter.api.Test;
+
+class WebSocketLoopTest {
+  @Test
+  void onOpenFailureStillReportsErrorClosesAndReleasesSession() {
+    RuntimeException failure = new RuntimeException("open failed");
+    AtomicReference<Throwable> reported = new AtomicReference<>();
+    AtomicInteger closes = new AtomicInteger();
+    WebSocketSession session =
+        new WebSocketSession(
+            new ByteArrayInputStream(new byte[0]), new ByteArrayOutputStream(), 128);
+
+    WebSocketLoop.run(
+        session,
+        new WebSocketHandler() {
+          @Override
+          public void onOpen(WebSocketSession opened) {
+            throw failure;
+          }
+
+          @Override
+          public void onMessage(WebSocketSession opened, WebSocketFrame frame) {}
+
+          @Override
+          public void onError(WebSocketSession opened, Throwable error) {
+            reported.set(error);
+          }
+
+          @Override
+          public void onClose(WebSocketSession opened, int code) {
+            closes.incrementAndGet();
+          }
+        });
+
+    assertSame(failure, reported.get());
+    assertEquals(1, closes.get());
+    assertFalse(session.isOpen());
+  }
+
+  @Test
+  void onCloseFailureCannotPreventTransportRelease() {
+    AtomicInteger inputCloses = new AtomicInteger();
+    WebSocketSession session =
+        new WebSocketSession(
+            new InputStream() {
+              @Override
+              public int read() {
+                return -1;
+              }
+
+              @Override
+              public void close() {
+                inputCloses.incrementAndGet();
+              }
+            },
+            new ByteArrayOutputStream(),
+            128);
+
+    assertThrows(
+        RuntimeException.class,
+        () ->
+            WebSocketLoop.run(
+                session,
+                new WebSocketHandler() {
+                  @Override
+                  public void onOpen(WebSocketSession opened) {}
+
+                  @Override
+                  public void onMessage(WebSocketSession opened, WebSocketFrame frame) {}
+
+                  @Override
+                  public void onClose(WebSocketSession opened, int code) {
+                    throw new RuntimeException("close failed");
+                  }
+                }));
+
+    assertEquals(1, inputCloses.get());
+    assertFalse(session.isOpen());
+  }
+}