feat(nexus): remove personal API keys, sign in with OAuth only

crates/eidos-gui/src/dialogs.rs

@@ -57,38 +57,51 @@ pub(crate) fn settings_dialog<'a>(app: &App) -> Element<'a, Message> {
 
     let body: Element<'a, Message> = match app.settings_tab {
         SettingsTab::Nexus => {
-            // The validate/connect button greys out while a check is in flight.
-            let connect_label = if app.api_key_validating { "Checking..." } else { "Validate & Save" };
-            let mut connect = button(text(connect_label).size(12.0)).padding([5, 12]).style(button::primary);
-            if !app.api_key_validating {
-                connect = connect.on_press(Message::ApiKeyValidateStart);
+            // Sign-in, and only sign-in. There is no personal-API-key field, on
+            // purpose: Nexus requires personal keys absent from a distributed
+            // client, not merely unused, so there is nothing here to enter.
+            let signed_in = app.nexus_account.is_some();
+            let label = if app.nexus_signing_in {
+                "Waiting for your browser..."
+            } else if signed_in {
+                "Sign in again"
+            } else {
+                "Sign in to Nexus Mods"
+            };
+            let mut action = button(text(label).size(12.0)).padding([5, 12]).style(button::primary);
+            if !app.nexus_signing_in {
+                action = action.on_press(Message::NexusSignInStart);
             }
-            // Masked. It is a credential, and this field sits in a window users
-            // screenshot to ask for help - which is one of the ways a key leaks.
-            // Nothing is lost by hiding it: validation names the account back, so
-            // the user still gets told whether what they pasted was right.
-            let field = text_input("Personal API key", &app.settings_api_key)
-                .secure(true)
-                .on_input(Message::ApiKeyChanged)
-                .on_submit(Message::ApiKeyValidateStart)
-                .padding(6)
-                .size(12.0)
-                .width(Length::Fill);
 
             let mut col = Column::new()
                 .spacing(8)
-                .push(text("Personal Nexus Mods API key").size(13.0))
+                .push(text("Nexus Mods account").size(13.0))
                 .push(
-                    text("Get it from nexusmods.com -> Account -> API Keys (Personal API Key). It is stored at ~/.config/eidos/nexus.ini and shared with the CLI.")
-                        .size(10.0),
-                )
-                .push(Row::new().spacing(8).push(field).push(connect));
+                    text(
+                        "Signing in opens your browser. The session is stored at \
+                         ~/.config/eidos/nexus.ini and shared with the CLI.",
+                    )
+                    .size(10.0),
+                );
+
+            let mut row = Row::new().spacing(8).push(action);
+            if signed_in {
+                row = row.push(
+                    button(text("Sign out").size(12.0))
+                        .padding([5, 12])
+                        .on_press(Message::NexusSignOut)
+                        .style(button::secondary),
+                );
+            }
+            col = col.push(row);
 
             if let Some(account) = &app.nexus_account {
                 let tier = if account.is_premium { "Premium" } else { "free" };
-                col = col.push(text(format!("Connected as {} ({tier}).", account.name)).size(11.0));
+                col = col.push(text(format!("Signed in as {} ({tier}).", account.name)).size(11.0));
+            } else {
+                col = col.push(text("Not signed in.").size(11.0));
             }
-            if let Some(err) = &app.api_key_error {
+            if let Some(err) = &app.nexus_error {
                 col = col.push(text(format!("Error: {err}")).size(11.0).color(Color::from_rgb8(0x8A, 0x2A, 0x2A)));
             }
             col.into()

crates/eidos-gui/src/main.rs

@@ -268,13 +268,13 @@ enum Message {
     /// Switch the Preferences tab (General / Nexus).
     SettingsTabSelected(SettingsTab),
     /// Edit the Nexus API key field.
-    ApiKeyChanged(String),
-    /// Validate + persist the entered Nexus API key.
-    ApiKeyValidateStart,
-    /// The key validation finished: the account on success, else an error.
-    /// Carries the key that was actually VALIDATED, so an edit made to the field
-    /// during the round-trip is never saved as if it had been checked.
-    ApiKeyValidateResult(String, Result<eidos_nexus::Account, String>),
+    /// Start the Nexus OAuth sign-in: open the browser, wait on the loopback
+    /// listener, exchange the code, store the session.
+    NexusSignInStart,
+    /// The sign-in finished: the account on success, else an error.
+    NexusSignInResult(Result<eidos_nexus::Account, String>),
+    /// Forget the stored Nexus session.
+    NexusSignOut,
     /// Set the preferred colour theme.
     ThemeChanged(PrefTheme),
     /// Set the default game id to open (`None` = none).
@@ -885,14 +885,13 @@ struct App {
     settings_open: bool,
     /// The active Preferences tab.
     settings_tab: SettingsTab,
-    /// The editable Nexus API key field.
-    settings_api_key: String,
-    /// The validated Nexus account, if the stored key checked out (or was cached).
+
+    /// The validated Nexus account, if a stored session checked out.
     nexus_account: Option<eidos_nexus::Account>,
-    /// A key validation is in flight (guards the button + concurrent validations).
-    api_key_validating: bool,
-    /// The last key-validation error, shown inline in the dialog.
-    api_key_error: Option<String>,
+    /// A sign-in is in flight (guards the button + concurrent attempts).
+    nexus_signing_in: bool,
+    /// The last sign-in error, shown inline in the dialog.
+    nexus_error: Option<String>,
     /// The persisted app-global preferences (theme, default game).
     prefs: Settings,
     // ---- Executables dialog ----

crates/eidos-gui/src/state.rs

@@ -112,10 +112,9 @@ pub(crate) fn new(launch_command: Vec<String>) -> (App, Task<Message>) {
         settings_tab: SettingsTab::Nexus,
         // Prefill the key field from the shared store (the same key `eidos nexus
         // key` writes), so it survives across sessions without a network round trip.
-        settings_api_key: eidos_instance::settings::load_nexus_key().unwrap_or_default(),
         nexus_account: None,
-        api_key_validating: false,
-        api_key_error: None,
+        nexus_signing_in: false,
+        nexus_error: None,
         prefs: Settings::load(),
         executables: None,
         endorsing: None,
@@ -214,17 +213,15 @@ pub(crate) fn new(launch_command: Vec<String>) -> (App, Task<Message>) {
     refresh_meta_cache(&mut app);
     app.collapsed = load_collapsed(&app);
     recompute_counts(&mut app);
-    // A stored key means the user IS connected: validate it in the background so
-    // the status bar shows the account instead of "not logged in" every session.
-    let startup = match load_nexus_api_key() {
-        Some(key) => Task::perform(
-            async move {
-                let result = eidos_nexus::Nexus::new(&key).validate();
-                (key, result)
-            },
-            |(key, result)| Message::ApiKeyValidateResult(key, result),
-        ),
-        None => Task::none(),
+    // A stored session means the user IS signed in: validate it in the background
+    // so the status bar shows the account instead of "not logged in" every session.
+    let startup = if eidos_nexus::Nexus::have_credentials() {
+        Task::perform(
+            async move { eidos_nexus::Nexus::connect().and_then(|n| n.validate()) },
+            Message::NexusSignInResult,
+        )
+    } else {
+        Task::none()
     };
     (app, startup)
 }
@@ -262,10 +259,38 @@ pub(crate) fn load_tools(app: &mut App) {
     app.tools = merged;
 }
 
-/// The stored Nexus API key (the same key the CLI's `eidos nexus key` writes),
-/// shared via `eidos-instance`'s settings store so the key never diverges.
-pub(crate) fn load_nexus_api_key() -> Option<String> {
-    eidos_instance::settings::load_nexus_key()
+/// Run the whole Nexus OAuth sign-in, blocking: build the PKCE challenge, hand
+/// the browser the authorize URL, wait on the loopback listener for the code,
+/// exchange it, and store the session.
+///
+/// Personal API keys are deliberately absent - Nexus requires them gone from a
+/// distributed client - so this is the ONLY way Eidos authenticates, and it
+/// needs a `client_id` registered with Nexus (`EIDOS_NEXUS_CLIENT_ID`).
+pub(crate) fn nexus_sign_in() -> Result<eidos_nexus::Account, String> {
+    use eidos_nexus::oauth;
+    let cfg = oauth::Config::from_env().ok_or_else(|| {
+        "no Nexus client_id configured: set EIDOS_NEXUS_CLIENT_ID (Eidos ships no \
+         default, so it cannot identify itself as another application)"
+            .to_string()
+    })?;
+    let pkce = oauth::Pkce::new().map_err(|e| e.to_string())?;
+    let state = oauth::random_token(32).map_err(|e| e.to_string())?;
+    let url = oauth::authorize_url(&cfg, &pkce, &state);
+    // Hand off to the browser BEFORE listening, so a failure to open is reported
+    // as itself rather than as a listener timeout two minutes later.
+    std::process::Command::new("xdg-open")
+        .arg(&url)
+        .spawn()
+        .map_err(|e| format!("could not open your browser: {e}"))?;
+    let code = oauth::wait_for_code(cfg.redirect_port, &state, std::time::Duration::from_secs(300))?;
+    let tokens = oauth::exchange_code(&cfg, &code, &pkce)?;
+    let mut creds = eidos_instance::settings::load_nexus_creds();
+    creds.access_token = Some(tokens.access_token.clone());
+    creds.refresh_token = Some(tokens.refresh_token);
+    creds.expires_at = tokens.expires_at;
+    eidos_instance::settings::save_nexus_creds(&creds)
+        .map_err(|e| format!("signed in, but could not store the session: {e}"))?;
+    eidos_nexus::Nexus::with_bearer(&tokens.access_token).validate()
 }
 
 /// Build the Executables editor state for the open instance: the user's tools.ini

crates/eidos-gui/src/update.rs

@@ -1878,60 +1878,47 @@ pub(crate) fn update_inner(app: &mut App, message: Message) -> Task<Message> {
         // ---- Settings / Preferences ------------------------------------------
         Message::OpenSettings => {
             app.menu_mod = None;
-            app.api_key_error = None;
-            // Re-read the stored key so the field reflects what's on disk.
-            app.settings_api_key = eidos_instance::settings::load_nexus_key().unwrap_or_default();
+            app.nexus_error = None;
             app.settings_open = true;
         }
         Message::CloseSettings => {
             app.settings_open = false;
-            app.api_key_error = None;
+            app.nexus_error = None;
         }
         Message::SettingsTabSelected(t) => app.settings_tab = t,
-        Message::ApiKeyChanged(s) => {
-            app.settings_api_key = s;
-            app.api_key_error = None;
-        }
-        Message::ApiKeyValidateStart => {
-            let key = app.settings_api_key.trim().to_string();
-            if key.is_empty() {
-                app.api_key_error = Some("Enter your personal Nexus API key.".to_string());
+        Message::NexusSignInStart => {
+            if app.nexus_signing_in {
                 return Task::none();
             }
-            if app.api_key_validating {
-                return Task::none();
-            }
-            app.api_key_validating = true;
-            app.api_key_error = None;
-            // Blocking ureq inside the async closure, like SortPlugins.
-            return Task::perform(
-                async move {
-                    let result = eidos_nexus::Nexus::new(&key).validate();
-                    (key, result)
-                },
-                |(key, result)| Message::ApiKeyValidateResult(key, result),
-            );
+            app.nexus_signing_in = true;
+            app.nexus_error = None;
+            app.status = Some("Opening your browser to sign in to Nexus...".to_string());
+            // The whole dance on a worker: browser hand-off, loopback listener,
+            // code exchange. Blocking calls inside the async closure, like the
+            // other network work here.
+            return Task::perform(async move { nexus_sign_in() }, Message::NexusSignInResult);
         }
-        Message::ApiKeyValidateResult(key, result) => {
-            app.api_key_validating = false;
+        Message::NexusSignInResult(result) => {
+            app.nexus_signing_in = false;
             match result {
                 Ok(account) => {
-                    // Persist the key that was validated (the field may have been
-                    // edited during the round-trip) so the CLI and a relaunch see it.
-                    let saved = eidos_instance::settings::save_nexus_key(&key);
-                    app.status = Some(match &saved {
-                        Ok(()) => format!(
-                            "Connected to Nexus as {} ({}).",
-                            account.name,
-                            if account.is_premium { "Premium" } else { "free" }
-                        ),
-                        Err(e) => format!("Validated, but could not save the key: {e}"),
-                    });
+                    app.status = Some(format!(
+                        "Signed in to Nexus as {} ({}).",
+                        account.name,
+                        if account.is_premium { "Premium" } else { "free" }
+                    ));
                     app.nexus_account = Some(account);
                 }
-                Err(e) => {
-                    app.api_key_error = Some(e);
+                Err(e) => app.nexus_error = Some(e),
+            }
+        }
+        Message::NexusSignOut => {
+            match eidos_instance::settings::clear_nexus_tokens() {
+                Ok(()) => {
+                    app.nexus_account = None;
+                    app.status = Some("Signed out of Nexus.".to_string());
                 }
+                Err(e) => app.nexus_error = Some(format!("could not sign out: {e}")),
             }
         }
         Message::ThemeChanged(t) => {