feat: add auto login to skip sign-in method chooser

If you combine OIDC with local accounts or if your OIDC provider is an
external company (Facebook, GitHub, …) it makes sense for HedgeDoc to
show a additional login modal so users know that they will leave the
page.

However, if OAuth2/OIDC is a deployment's primary sign-in method and a
local OIDC provider is being used, users expect the common SSO method
being used, and he "Choose method" modal is a redundant extra click.
Essentially, you may have to click login thrice:

- Click login -> modal opens
- Click Login with provider -> provider login opens
- Log in (unless you are logged in already)

This simple patch adds an auto-login configuration, which makes the Sign
In button link straight to the provider's OAuth2 flow, improving the UX
of tHedgeDoc's login.

Signed-off-by: Lars Kiesow <lkiesow@uos.de>

app.js

@@ -253,6 +253,15 @@ app.locals.authProviders = {
   allowEmailRegister: config.allowEmailRegister
 }
 
+// If none of the form-based methods (LDAP, Email, OpenID) are configured and
+// exactly one redirect-style external provider is, skip the "Choose method"
+// dialog and link "Sign In" straight to that provider's login page.
+const externalProviderKeys = ['facebook', 'twitter', 'github', 'gitlab', 'mattermost', 'dropbox', 'google', 'saml', 'oauth2']
+const enabledExternalProviders = externalProviderKeys.filter((key) => app.locals.authProviders[key])
+app.locals.authProviders.autoLoginProvider = (!app.locals.authProviders.ldap && !app.locals.authProviders.email && !app.locals.authProviders.openID && enabledExternalProviders.length === 1)
+  ? enabledExternalProviders[0]
+  : null
+
 // Export/Import menu items
 app.locals.enableDropBoxSave = config.isDropboxEnable
 app.locals.enableGitHubGist = config.isGitHubEnable

public/docs/release-notes.md

@@ -1,5 +1,11 @@
 # Release Notes
 
+## <i class="fa fa-tag"></i> 1.x.x <i class="fa fa-calendar-o"></i> UNRELEASED
+
+### Enhancements
+
+- Automatically skip the login modal if no form-based login and exactly one external login provider is configured
+
 ## <i class="fa fa-tag"></i> 1.11.1 <i class="fa fa-calendar-o"></i> 2026-07-24
 
 ### Security fixes

public/views/index/body.ejs

@@ -15,7 +15,9 @@
                                 <% if (allowAnonymous && !disableNoteCreation) { %>
                                 <a type="button" href="<%- serverURL %>/new" class="btn btn-sm btn-primary"><i class="fa fa-plus"></i> <%= __('New guest note') %></a>
                                 <% } %>
-                                <% if (authProviders.facebook || authProviders.twitter || authProviders.github || authProviders.gitlab || authProviders.mattermost || authProviders.dropbox || authProviders.google || authProviders.ldap || authProviders.saml || authProviders.oauth2 || authProviders.email) { %>
+                                <% if (authProviders.autoLoginProvider) { %>
+                                <a type="button" href="<%- serverURL %>/auth/<%- authProviders.autoLoginProvider %>" class="btn btn-sm btn-success ui-signin"><%= __('Sign In') %></a>
+                                <% } else if (authProviders.facebook || authProviders.twitter || authProviders.github || authProviders.gitlab || authProviders.mattermost || authProviders.dropbox || authProviders.google || authProviders.ldap || authProviders.saml || authProviders.oauth2 || authProviders.email) { %>
                                 <button class="btn btn-sm btn-success ui-signin" data-toggle="modal" data-target=".signin-modal"><%= __('Sign In') %></button>
                                 <% } %>
                             </div>
@@ -52,7 +54,13 @@
                     <% if (errorMessage && errorMessage.length > 0) { %>
                     <div class="alert alert-danger" style="max-width: 400px; margin: 0 auto;"><%= errorMessage %></div>
                     <% } %>
-                    <% if (authProviders.facebook || authProviders.twitter || authProviders.github || authProviders.gitlab || authProviders.mattermost || authProviders.dropbox || authProviders.google || authProviders.ldap || authProviders.saml || authProviders.oauth2 || authProviders.email) { %>
+                    <% if (authProviders.autoLoginProvider) { %>
+                    <span class="ui-signin">
+                        <br>
+                        <a type="button" href="<%- serverURL %>/auth/<%- authProviders.autoLoginProvider %>" class="btn btn-lg btn-success ui-signin" style="min-width: 200px;"><%= __('Sign In') %></a>
+                    </span>
+                    <span class="ui-or"><%= __('or') %></span>
+                    <% } else if (authProviders.facebook || authProviders.twitter || authProviders.github || authProviders.gitlab || authProviders.mattermost || authProviders.dropbox || authProviders.google || authProviders.ldap || authProviders.saml || authProviders.oauth2 || authProviders.email) { %>
                     <span class="ui-signin">
                         <br>
                         <a type="button" class="btn btn-lg btn-success ui-signin" data-toggle="modal" data-target=".signin-modal" style="min-width: 200px;"><%= __('Sign In') %></a>