Create a draft pull request implementing proper WebSocket close semantics in repo gemini-hlsw/clue.

Context

• Current issue: WebSocket client disconnect does not actually close the underlying connection.
• In http4s/src/main/scala/clue/http4s/Http4sWebSocketBackend.scala, class Http4sWSConnection.closeInternal is currently a no-op (Concurrent[F].unit // TODO).
• Http4sWebSocketBackend.connect uses connectHighLevel(...).allocated and starts a fiber to drain connection.receiveStream, and only calls release in the stream finalizer.
• This leads to leaked connections/fibers, test timeouts, and in newer JDK HttpClient WebSocket implementations (JDK 21/25) errors like IllegalArgumentException: statusCode on close.

User request

• Open a PR on a new branch fix-ws-close.
• Mention that it was requested by @hugo-vrijswijk.
• Keep PR as draft.

Goals

1. Implement real close behavior so ApolloClient.disconnect() actually closes the socket when using Http4sWebSocketBackend.
2. Ensure resources/fibers started in Http4sWebSocketBackend.connect are cleaned up deterministically on disconnect.
3. Avoid hanging receive fibers and ensure release from .allocated is always invoked.
4. Preserve existing behavior for message handling and handler.onClose callbacks, but ensure they are triggered appropriately during explicit client disconnect.

Suggested implementation direction (agent may adjust as needed after exploring repo/docs)

• In Http4sWebSocketBackend.connect, manage lifecycle with Resource/allocatedCase or store:
  • the listener fiber
  • the release action
  • a "closed" signal to prevent double-close
• Implement Http4sWSConnection.closeInternal to:
  • attempt to send a close frame if possible (use available http4s WSConnectionHighLevel APIs)
  • otherwise at least cancel the listener fiber and invoke release
  • be idempotent
• Ensure that closing the connection causes the receive stream to complete, so onFinalizeCase runs; but also guard against duplicate onClose calls.

Acceptance criteria

• Unit/integration tests should no longer hang due to leaked websocket connections.
• Disconnect triggers closure promptly.
• PR includes clear explanation in description, including mention of JDK 21/25 stricter close handling and that this PR addresses the root cause (no-op close).

References

• File: http4s/src/main/scala/clue/http4s/Http4sWebSocketBackend.scala
• File: core/src/main/scala/clue/websocket/ApolloClient.scala (disconnect calls connection.closeInternal)

Branch

• Create and use branch fix-ws-close.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: ```
20:22:00.632 [INFO ] org.http4s.ember.server.EmberServerBuilderCompanionPlatform - Ember-Server service bound to address: 127.0.0.1:8080
20:22:00.764 [DEBUG] lucuma-odb-test - GET web socket: Request(method=GET, uri=/ws, httpVersion=HTTP/1.1, headers=Headers(Connection: Upgrade, Host: 127.0.0.1:8080, Upgrade: websocket, User-Agent: Java-http-client/25.0.2, Sec-WebSocket-Key: QgjjxBT0IVwNGjHyw7+EIw==, Sec-WebSocket-Protocol: graphql-transport-ws, Sec-WebSocket-Version: 13))
20:22:00.792 [DEBUG] lucuma-odb-test - Received Text frame (last=true) from client: {
"type" : "connection_init",
"payload" : {
"Authorization" : "Bearer bob"
}
}
20:22:00.808 [DEBUG] lucuma-odb-test - received ConnectionInit(Some(object[Authorization -> "Bearer bob"]))
20:22:00.902 [DEBUG] lucuma-odb-test - Subscriptions send Some(Right(ConnectionAck(None))) enqueued
20:22:00.902 [DEBUG] lucuma-odb-test - Subscriptions send Some(Right(Ping(None))) enqueued
20:22:00.906 [DEBUG] lucuma-odb-test - Sending to client: {
"type" : "connection_ack"
}
20:22:00.908 [DEBUG] lucuma-odb-test - Sending Ping
20:22:00.923 [DEBUG] lucuma-odb-test - Received Text frame (last=true) from client: {
"type" : "subscribe",
"id" : "query-foo-6cc1dc8d-f2ba-4224-a287-39f373098624",
"payload" : {
"query" : "query { foo }"
}
}
20:22:00.924 [DEBUG] lucuma-odb-test - received Subscribe(query-foo-6cc1dc8d-f2ba-4224-a287-39f373098624,GraphQLRequest(query { foo },None,None,None))
20:22:00.968 [DEBUG] lucuma-odb-test - Subscriptions send Some(Right(Next(query-foo-6cc1dc8d-f2ba-4224-a287-39f373098624,GraphQLResponse(Right({
"foo" : 42
}),None)))) enqueued
20:22:00.968 [DEBUG] lucuma-odb-test - Subscriptions send Some(Right(Complete(query-foo-6cc1dc8d-f2ba-4224-a287-39f373098624))) enqueued
20:22:00.970 [DEBUG] lucuma-odb-test - Sending to client: {
"type" : "next",
"id" : "query-foo-6cc1dc8d-f2ba-4224-a287-39f373098624",
"payload" : {
"data" : {
"foo" : 42
}
}
}
20:22:00.971 [DEBUG] lucuma-odb-test - Sending to client: {
"type" : "complete",
"id" : "query-foo-6cc1dc8d-f2ba-4224-a287-39f373098624"
}
20:22:05.795 [DEBUG] lucuma-odb-test - Sending Ping
20:22:10.792 [DEBUG] lucuma-odb-test - Sending Ping
Test run lucuma.graphql.routes.AuthSuite s...