Allow MSAL token cache to use GCM's collection of secure storage options

Platform: ARM64
OS: Ubuntu 24.04 Noble
Git Version: 2.54.0

Simple output:

warning: cannot persist Microsoft authentication token cache securely!
warning: using plain-text fallback token cache
To sign in, use a web browser to open the page https://login.microsoft.com/device and enter the code I6H4VXSFQ to authenticate.

Debug output (GCM_TRACE=1):

<...omitted>
15:58:18.019798 ...sHostProvider.cs:259 trace: [GeneratePersonalAccessTokenAsync] Getting Azure AD access token...
15:58:18.022886 ...uthentication.cs:146 trace: [GetTokenForUserAsync] OS broker is not available or enabled.
15:58:18.022923 ...uthentication.cs:152 trace: [GetTokenForUserAsync] MSA passthrough is enabled.
15:58:18.041199 ...uthentication.cs:677 trace: [RegisterTokenCacheAsync] Configuring MSAL token cache...
warning: cannot persist Microsoft authentication token cache securely!
15:58:18.082464 ...uthentication.cs:701 trace: [RegisterTokenCacheAsync] Cannot persist Microsoft Authentication data securely!
15:58:18.082720 ...uthentication.cs:702 trace: [RegisterTokenCacheAsync] ! error: 'Persistence check failed. Reason: An exception was encountered while processing libsecret error information during saving in the Storage. Error code: 0. OS error code 0.'.
15:58:18.082754 ...uthentication.cs:702 trace: [RegisterTokenCacheAsync]        > 'An exception was encountered while processing libsecret error information during saving in the Storage. Error code: 0'.
15:58:18.082770 ...uthentication.cs:702 trace: [RegisterTokenCacheAsync]        > 'An error was encountered while saving secret to keyring in the Storage domain:'94' code:'2' message:'The name org.freedesktop.secrets was not provided by any .service files' .Error code: 2'.
warning: using plain-text fallback token cache
15:58:18.083161 ...uthentication.cs:718 trace: [RegisterTokenCacheAsync] Using fall-back plaintext token cache on Linux.
15:58:18.084285 ...uthentication.cs:732 trace: [RegisterTokenCacheAsync] Token cache configured.
15:58:18.089845 ...uthentication.cs:258 trace: [GetTokenForUserAsync] Performing interactive auth with device code...
15:58:18.123327 ...pClientFactory.cs:60 trace: [CreateClient] Creating new HTTP client instance...
15:58:18.123501 ...pClientFactory.cs:80 trace: [CreateClient] Git's SSL/TLS backend is: OpenSsl
To sign in, use a web browser to open the page https://login.microsoft.com/device and enter the code ILV652G9S to authenticate.

It seems that GCM is trying to use org.freedesktop.secrets API rather than GPG. But I have GCM_CREDENTIAL_STORE=gpg and global Git config credential.credentialStore=gpg

I have pass inited and pinenty-tty set.

Start in Authentication.cs at RegisterTokenCacheAsync, around the trace lines 677–732, and trace how credential.credentialStore and GCM_CREDENTIAL_STORE are handled. Compare that path with GCM’s other secure-storage options. Done means the configured GPG/pass storage can be used for the MSAL token cache without falling back to plaintext, with the relevant authentication behavior verified.