Coldcard signing issues with a multisig transaction.

[Cyberwiz9000]

Describe the bug
When signing in a 2 of 3 multisig with a Coldcard device, Specter shows several popup windows incorrectly.

To Reproduce
Steps to reproduce the behavior:

1. Create a 2 of 3 multisig transaction that includes a coldcard device.
2. Under the Transaction Details with Sign Transaction window, choose the Coldcard device.
3. Choose sign via USB (first time).
   If I start with the Coldcard device, I get the question "Do you really want to use your Coldcard over USB?".

If I start with the Trezor device first and second with the Coldcard device I get both the question and the USB choice.

4. I click "Yes" on the question.
   Specter goes back to the Transaction Details with Sign Transaction window with the device options.
5. Choose the Coldcard device again in the Device list, then you get the following;

6. Choose sign via USB (second time), then you get the following:

7. Choose sign via USB (third time),
8. Plug in the Coldcard device, input pin code, choose ready to sign.
9. The transaction comes through to the Coldcard device, I can sign and thus the signing is now completed correctly.

Expected behavior
Signing should work correctly like it works with Trezor and Ledger. I should get only one popup asking to connect the Coldcard device, then be able to choose the Coldcard device and finish the signing.

Preferably the question "Do you really want to use your Coldcard over USB?" is removed. Or have the option in Specter to disable this question.
The question is at least one of the issues messing up the workflow.

I don't think the question adds to the overall security, including for new users, if it makes the workflow unreliable.
Also, I imagine people using Specter in a multisig setup using Coldcard as one of the signing devices understand the risk of using USB.

Desktop (please complete the following information):
My node is Bitcoin Core 30.2 and 29.3 running locally on Linux Mint.
Specter runs as an imageApp on the same Linux Mint.
Specter Version 2.1.8

Additional context
I don't have these issues with Ledger nor Trezor devices
I remember having similar issues in previous versions of Specter with Coldcard, but not as bad as now, afaik.

Another issues that happens is that I get the detecting Coldcard device window popup when I am already done signing with the Coldcard. I can then click away and proceed with doing the transaction with no further issues.
Also a similar issue is that after signing with the Coldcard, and then choosing another device (i.e. Trezor), the "detecting coldcard usb" windows pops up, then I have to click away and choose the Trezor device again, and then it works as expected.

Finally when I connect the Coldcard before choosing it in the Specter Sign Transaction window, a "detecting plug in your device" window pops up but nothing happens. I then have to click away, and choose the Coldcard again. I then get the question "Do you really want to use your Coldcard over USB?" again, but the signing completes without answering the question.

With a single sig the issues are less pronounced, been a while since I did these with a Coldcard though.

[al-munazzim]

Thanks for the detailed report and screenshots — this is helpful.

I had a look at the Coldcard USB flow in the current frontend code. One likely problem area is the special Coldcard handling in templates/includes/hwi/hwi.jinja: enumerate(deviceTypes='coldcard', ...) appends the coldcard_warning prompt when coldcardUsb == 0, but the flow then continues into the normal device-detection/progress overlay path. When clicking the warning button, coldCardNotice() only sets coldcardUsb = 1 and cancels the overlay; it does not obviously resume the original signing/enumeration action. That matches your observation that you have to choose the Coldcard/sign-via-USB path multiple times before the signing finally proceeds.

So this looks like a UI state-machine issue rather than a Coldcard signing failure itself: the actual signing eventually works, but the warning/detection overlays are not sequenced cleanly, especially in multisig and when switching between devices.

A few things that would help qualify/reproduce this precisely:

1. Is this with HWI Bridge or local HWI? If HWI Bridge, which version?
2. Which Coldcard model + firmware version?
3. Does it reproduce on a fresh browser session / after hard reload, or only after signing with another device first?
4. In browser devtools, do you see multiple calls to /hwi/api/ during the repeated popups, or any JS console errors?
5. Does disabling the Coldcard USB warning locally make the workflow behave normally, or do the repeated “detecting” overlays still happen?

From the code path, a likely fix would be to make the Coldcard USB warning an explicit awaited/terminal step before enumerate() proceeds, or to remember the acceptance and immediately continue the same signing action instead of cancelling the overlay and requiring the user to start again.

[k9ert]

@al-munazzim Can you potentially create an integration test for this scenario? It would be a good base for fixing the issue. AFAIK usb connections can be faked via a port, no?!