POST /auth/link returns 401 credentials_rejected for at least one library (Mid-Continent Public Library, websiteId 339) despite valid credentials

[mrmichael1389]

Running libby auth (node bin/libby.mjs auth --insecure-tls, with LIBBY_CARD/LIBBY_PIN/LIBBY_LIBRARY=mcpl/LIBBY_WEBSITE=339 set) consistently fails:

Minting primary chip...
Sentry error: POST /auth/link/339 -> 401 (credentials_rejected)

The credentials are confirmed valid — verified by successfully re-authenticating with the exact same card number and PIN via the official Libby app's own "re-verify card" feature, immediately before and after this test.

--insecure-tls is set and the request reaches the server fine (a real 401 with a body, not a connection error), so this isn't the known cert-mismatch issue.

Environment: Node v24.14.1, Windows, commit abea983 (2026-07-11), package v0.4.0.

[JavaGT]

@mrmichael1389 I pushed a fix in commit 2668754.

The auth flow now uses the library-system identifier returned by Libby’s /auth/forms/{websiteId} endpoint. For MCPL, this correctly changes the identifier from mcpl to midcon. I also updated the client version to the current live Libby version (22.1.1).

Could you please test the latest main with your MCPL card and PIN, then report whether libby auth succeeds? Please do not post your card number or PIN in this issue. If it still fails, include the HTTP result/error text and the commit tested.