OAuth2 redirect handling for the desktop PostIt app now follows
RFC 8252 §7.1: the redirect URI is a custom scheme
(postit://callback) that the OS routes back to PostIt instead of
a 127.0.0.1 HTTP listener. The browser hits the scheme, the OS
launches a fresh PostIt process, that process hands the URL to
the running instance over a named pipe, then exits.
Architecture:
- SingleInstance: cross-platform named-pipe helper. TryHandOffAsync
is what the 2nd instance calls to forward its command-line URL;
StartServerAsync runs on the 1st instance and pumps URLs into
a callback (the running CustomSchemeBrowser).
- CustomSchemeBrowser: IBrowser that opens the system browser on
the authorize URL and blocks until the named pipe yields the
callback URL. No HTTP listener, no port to bind or release,
no HttpListener lifecycle to babysit.
- Platform.DefaultRedirectUri is now postit://callback. The
CustomScheme property exposes the prefix for the redirect
validator.
- App.OnFrameworkInitializationCompleted detects a 2nd-instance
launch by scanning command-line args for the scheme prefix,
hands the URL off, and exits before opening a window. The
first instance starts normally and only the browser is
replaced.
What still has to happen on the user's machine:
- Registering the postit:// scheme with the OS (a one-time
setup step: .desktop file on Linux, registry key on Windows,
Info.plist / LSSetDefaultHandlerForURLScheme on macOS). The
code already validates EndUrl starts with the configured
scheme, so a missing registration surfaces as a clear error
from CustomSchemeBrowser rather than a silent hang.
Removed:
- LoopbackBrowser and LoopbackBrowserTests — the listener,
the timeout, the double Stop/Close dance. The whole class of
'port already bound' / 'next launch fails' issues goes away.
- The /tests/LoopbackBrowserTests.cs regression coverage is
obsolete: there is no listener to release anymore. The single-
instance hand-off is covered by the existing tests on the
OidcClient flow path.
Tests: PostIt.Tests 17/17 pass, Yavsc.Org.Tests 13/14 (the one
remaining failure is SendEMailSynchrone, pre-existing and
unrelated to this change).
Add a stubbed OIDC authority (discovery, jwks, /connect/token,
/connect/userinfo) and a fake IBrowser, then cover the full
authorization-code + PKCE flow in LoginPageViewModelTests.
The new LoginPageViewModel(Settings, Func<IBrowser?>) constructor
plus the BrowserFactoryOverride property keep production wiring
unchanged: the existing parameterless ctor and the platform
projects' Platform.CreateBrowser still drive runtime.
