feat(editor): open the Openverse register link from Settings → Images

The "Register at Openverse" link in Settings → Images → Advanced was painted
but inert. Add a hit-test (register_link_rect → ImagesHit::OpenRegisterLink →
AgentSettingsHit::OpenImageRegisterLink) and open
https://api.openverse.org/v1/auth_tokens/register/ on click — default browser
on desktop (open/xdg-open/start) and a new tab on web (window.open).

crates/op-editor-ui/src/widgets/agent_settings_images.rs

@@ -29,6 +29,10 @@ const ADD_BTN_W: f32 = 72.0;
 const BTN_H: f32 = 28.0;
 const BODY_GAP: f32 = 14.0;
 const REGISTER_ROW_H: f32 = 36.0;
+// Fixed hit-rect width for the "Register at Openverse" link. Covers the
+// link text + trailing chevron across all locales without reaching the
+// right-aligned Test button.
+const REGISTER_LINK_W: f32 = 220.0;
 const PROFILE_ROW_H: f32 = 32.0;
 const PROFILE_ROW_GAP: f32 = 6.0;
 const PROFILE_ROW_INSET_X: f32 = 8.0;
@@ -48,6 +52,7 @@ const PROVIDER_OPTION_H: f32 = 24.0;
 pub enum ImagesHit {
     ToggleAdvanced,
     FocusSearchField(ImageSearchField),
+    OpenRegisterLink,
     TestSearch,
     AddGenConfig,
     ToggleGenConfigEditor(usize),
@@ -117,6 +122,18 @@ fn register_link_y(content: Rect) -> f32 {
     content.origin.y + TITLE_H + ADVANCED_ROW_H + SUBTITLE_H + ROW_H + ROW_VGAP + ROW_H + BODY_GAP
 }
 
+/// Click target for the "Register at Openverse" link (text + chevron).
+/// A fixed `REGISTER_LINK_W` width covers every locale's link label
+/// without reaching the right-aligned Test button.
+pub(super) fn register_link_rect(content: Rect) -> Rect {
+    Rect::xywh(
+        content.origin.x,
+        register_link_y(content),
+        REGISTER_LINK_W,
+        REGISTER_ROW_H,
+    )
+}
+
 #[rustfmt::skip]
 fn search_field_rect(content: Rect, index: usize) -> Rect {
     let y = content.origin.y
@@ -249,6 +266,9 @@ pub fn hit_test(content: Rect, settings: &AgentSettings, scrolled: Point2D) -> I
         if (search_field_rect(content, 1)).contains(scrolled) {
             return ImagesHit::FocusSearchField(ImageSearchField::ClientSecret);
         }
+        if (register_link_rect(content)).contains(scrolled) {
+            return ImagesHit::OpenRegisterLink;
+        }
         if search_test_enabled(settings) && (test_btn_rect(content, settings)).contains(scrolled) {
             return ImagesHit::TestSearch;
         }

crates/op-editor-ui/src/widgets/agent_settings_images_profile_tests.rs

@@ -644,3 +644,30 @@ fn expanded_image_gen_profile_card_is_inset_from_content_clip_edges() {
         "profile card should leave horizontal room inside the clipped content area"
     );
 }
+
+#[test]
+fn images_register_link_hit_test_returns_open_register_link() {
+    use crate::widgets::agent_settings_images::{self, register_link_rect, ImagesHit};
+    use crate::widgets::agent_settings_panel_geometry::content_rect;
+
+    let mut state = EditorState::default();
+    state.editor_ui.agent_settings.tab = AgentSettingsTab::Images;
+    state.editor_ui.agent_settings.images_advanced_open = true;
+
+    let panel = AgentSettingsPanel::for_editor(&state);
+    let rect = panel.rect(1200.0, 800.0);
+    let content = content_rect(rect);
+
+    // Aim at the centre of the link's click target.
+    let link = register_link_rect(content);
+    let point = Point2D::new(
+        link.origin.x + link.size.x / 2.0,
+        link.origin.y + link.size.y / 2.0,
+    );
+
+    assert_eq!(
+        agent_settings_images::hit_test(content, &state.editor_ui.agent_settings, point),
+        ImagesHit::OpenRegisterLink,
+        "clicking the Register-at-Openverse link should map to OpenRegisterLink"
+    );
+}

crates/op-editor-ui/src/widgets/agent_settings_panel.rs

@@ -83,6 +83,7 @@ pub enum AgentSettingsHit {
     CopyMcpClientConfig,
     ToggleImagesAdvanced,
     FocusSearchField(ImageSearchField),
+    OpenImageRegisterLink,
     TestImageSearch,
     AddGenConfig,
     ToggleGenConfigEditor(usize),
@@ -249,6 +250,9 @@ impl<'a> AgentSettingsPanel<'a> {
                     ImagesHit::FocusSearchField(field) => {
                         return AgentSettingsHit::FocusSearchField(field);
                     }
+                    ImagesHit::OpenRegisterLink => {
+                        return AgentSettingsHit::OpenImageRegisterLink;
+                    }
                     ImagesHit::TestSearch => return AgentSettingsHit::TestImageSearch,
                     ImagesHit::AddGenConfig => return AgentSettingsHit::AddGenConfig,
                     ImagesHit::ToggleGenConfigEditor(index) => {

crates/op-host-native/src/widget_host/press_helpers.rs

@@ -169,6 +169,10 @@ impl WidgetHostNative {
                 );
                 self.set_settings_input_text(text);
             }
+            AgentSettingsHit::OpenImageRegisterLink => {
+                self.commit_settings_focus_if_any();
+                open_external_url("https://api.openverse.org/v1/auth_tokens/register/");
+            }
             AgentSettingsHit::TestImageSearch => {
                 self.commit_settings_focus_if_any();
                 let settings = &mut self.editor_state.editor_ui.agent_settings;
@@ -884,6 +888,21 @@ pub(in crate::widget_host) fn color_target(
     }
 }
 
+/// Open `url` in the user's default browser. Spawns the platform's
+/// URL launcher detached and ignores any error — opening a help link
+/// must never block or panic the editor. Used by the agent-settings
+/// "Register at Openverse" link.
+fn open_external_url(url: &str) {
+    #[cfg(target_os = "macos")]
+    let _ = std::process::Command::new("open").arg(url).spawn();
+    #[cfg(target_os = "windows")]
+    let _ = std::process::Command::new("cmd")
+        .args(["/C", "start", "", url])
+        .spawn();
+    #[cfg(not(any(target_os = "macos", target_os = "windows")))]
+    let _ = std::process::Command::new("xdg-open").arg(url).spawn();
+}
+
 #[cfg(test)]
 mod tests {
     use super::create_initial_size_for_tool;

crates/op-host-web/src/widget_host/agent_settings_press.rs

@@ -110,6 +110,15 @@ impl WidgetHost {
                     Some(SettingsFocus::ImageSearch(field));
                 self.set_settings_input_text(text);
             }
+            AgentSettingsHit::OpenImageRegisterLink => {
+                self.commit_settings_focus();
+                if let Some(w) = web_sys::window() {
+                    let _ = w.open_with_url_and_target(
+                        "https://api.openverse.org/v1/auth_tokens/register/",
+                        "_blank",
+                    );
+                }
+            }
             AgentSettingsHit::TestImageSearch => {
                 self.commit_settings_focus();
                 let settings = &mut self.editor_state.editor_ui.agent_settings;