…nteractive payloads can cause unhandled promise rejections that crash the Node.js process.

This commit fixes the issue reported at packages/adapter-slack/src/index.ts:1152

**Bug Analysis:**

In `routeSocketEvent` (line 1150), which is a synchronous `void` method, two async operations produce floating promises:

1.  `this.handleSlashCommand(params)` (line 1165) - `handleSlashCommand` is `async` and always returns a `Promise<Response>`. It calls `await this.lookupUser(userId)` which internally calls `await this.chat.getState().get()` (before the try/catch around the API call), and `this.chat.processSlashCommand()`. Any of these could throw.
    
2.  `this.dispatchInteractivePayload(payload)` (line 1172) - Returns `Response | Promise<Response>`. When the payload type is `view_submission`, it delegates to `async handleViewSubmission()`, which calls `await this.chat.processModalSubmit()` and accesses `payload.view.state.values` (which could throw on malformed payloads).
    

Since `routeSocketEvent` is synchronous (`void` return type) and called from a sync context within the socket mode event handler (after `await ack()` has already completed), these returned promises are fire-and-forget. If any reject, it triggers an unhandled promise rejection, which in Node.js 15+ terminates the process by default.

In contrast, in the webhook code path (`handleWebhook`), these same methods are always `return`-ed from async functions, so their promises are properly chained to the caller.

**Fix:**

Added `.catch()` handlers to both floating promises:

1.  For `handleSlashCommand`: Added `.catch()` that logs the error via `this.logger.error`.
2.  For `dispatchInteractivePayload`: Since it returns `Response | Promise<Response>` (only a Promise for `view_submission`), used `instanceof Promise` to conditionally attach a `.catch()` handler only when the result is a Promise.

This approach was chosen over making `routeSocketEvent` async because: (a) it doesn't change the method signature, (b) the caller doesn't need to await it (the ack has already been sent), and (c) errors are logged rather than silently swallowed.


Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com>
Co-authored-by: haydenbleasel <[email protected]>

- Export SlackForwardedSocketEvent type
- Add x-slack-socket-token check at top of handleWebhook() for forwarded events
- Update routeSocketEvent() to accept WebhookOptions and use waitUntil
- Add startSocketModeListener(), runSocketModeListener(), forwardSocketEvent()

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Make signingSecret optional (string | undefined) instead of falling
back to "". verifySignature now returns false when no secret is
configured, preventing HMAC with an empty key from silently passing.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Co-Authored-By: Claude Opus 4.6 <[email protected]>