fix(web-client): add missing setSignCb method to WebClient class

[bigeez]

Summary

Adds a missing setSignCb method to the WebClient class in crates/web-client/js/index.js. The method is declared in js/types/index.d.ts and called by MidenProvider.tsx, but was never actually implemented on the class.

Problem

The TypeScript declarations advertise setSignCb(signCb: SignCallback | null | undefined): void as part of the WebClient API. MidenProvider.tsx calls store.client.setSignCb(wrappedSignCb) whenever an external signer reconnects (e.g. after a page focus/blur cycle, wallet unlock, or token refresh).

However, the actual WebClient class only assigns this.signCb = signCb once in the constructor and never exposes a setter. The createClientProxy get trap therefore returns undefined for setSignCb, and calling undefined(wrappedSignCb) throws:This affects every user with an external signer (Para, Turnkey, MidenFi wallet adapter) on any signer reconnect.

Why tests didn't catch it

The mocks in __tests__/mocks/miden-sdk.ts:262 and __tests__/setup.ts:64 patch setSignCb as vi.fn(), satisfying the type contract while silently papering over the missing implementation. No test exercises this code path against the real proxy.

Fix

Added a setSignCb method to WebClient next to other lifecycle/control methods, following the same pattern as this.signCb constructor assignment and using ?? null to match the declared SignCallback | null | undefined type.

setSignCb(signCb) {
  this.signCb = signCb ?? null;
}

The message handler at line 459 already reads this.signCb fresh on every callback invocation, so a simple property assignment is all that's needed.

Changes

• 1 file changed, 14 insertions(+)
• crates/web-client/js/index.js

[bigeez]

Hey @WiktorStarczewski — could you approve the CI workflows when you get a chance? Happy to update the branch in the meantime. Let me know if anything needs changing on the implementation side.