Awaiting in the upgradeWebSocket callback prevents the websocket events from being registered correctly

[Rick-Phoenix]

What version of Hono are you using?

4.6.15

What runtime/platform is your app running on? (with version if possible)

Node 22

What steps can reproduce the bug?

• Use the upgradeWebSocket helper on a route
• Await anything inside of it
  (Even this will cause the same result)

await new Promise((resolve) => {
          setTimeout(() => {
            resolve(`Delay`);
          }, 0);
        });

What is the expected behavior?

• The promises inside the callback should resolve and the websocket events should be registered normally

What do you see instead?

• The connection is completed but events don't get registered (more details below)

Additional information

Awaiting in the callback seems to mess with the order of operations.
When not awaiting anything (whether the callback is async or not doesn't matter), the order of operation as seen in the debugger is this:
(the functions referenced here come from index.mjs in the @hono/node-ws package)

1. createEvents (the callback given to the upgradeWebSocket helper) is awaited
2. The callback returns
3. nodeUpgradeWebSocket is awaited
4. wss.handleUpgrade runs (so wss.emit 'connection' runs)
5. Events are created (starting with events.onOpen?.(new Event("open"), ctx))

While awaiting, the order changes and looks like this

1. createEvents (the callback given to the upgradeWebSocket helper) is awaited
2. The promise inside the callback is awaited (so the callback hasn't returned the events yet)
3. wss.handleUpgrade with 'emit connection' gets called right after, even if no events have been returned yet
4. Now the callback returns the events
5. nodeUpgradeWebSocket is awaited
6. Events do not get created and attached to the webSocket, so the webSocket connection does complete, but with no events attached.

Moving the awaiting inside one of the events (onOpen, for example) or even earlier with a preceding middleware works fine.

[Rick-Phoenix]

Just realized I opened this in the Hono repository and not the middleware repo. Sorry about that. If you can move it to there somehow let me know, otherwise I'll close it and reopen it there.

[yusukebe]

Hi @Rick-Phoenix

Does that mean this is @hono/node-ws's problem?

[Rick-Phoenix]

Indeed @yusukebe

[yusukebe]

@Rick-Phoenix I transferred the issue to honojs/middleware.

[yusukebe]

Hi @nakasyou

Do you have time to look at it?

[nakasyou]

@yusukebe, the problem fixed in #959. Could you check this?