feat(plugin): add a Plugin Manager window listing installed add-ons

Read-only inventory of the add-ons compiled into the build — name, version,
id, API level, description, command prefixes — built from the extracted
`ocs_plugin_api` manifest. Opened with the `PLUGINS` / `PLUGINMANAGER` command
or the Start-page "Plugins" button.

Adds `installed_manifests()` to the plugin registry and wires the window the
same way as the existing About / Shortcuts windows.

Part of #100 (phase-1 plugin manager UI stub).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/plugin-architecture.md

@@ -255,7 +255,7 @@ This mirrors QGIS: the application ships core menus; plugins add tabs/tools with
 - [x] Storm Sewer off `commands.rs` monolith
 - [x] Single registration (`plugin.toml` + `BuiltinPlugin::ribbon`)
 - [~] Extract `ocs_plugin_api` crate — manifest + ribbon/`CadModule` done; `acadrust`-typed host surface pending
-- [ ] Plugin manager UI stub (list installed, versions)
+- [x] Plugin manager UI stub (list installed, versions) — `PLUGINS` / `PLUGINMANAGER` command, or the Start-page "Plugins" button
 
 ### Phase 2 — Dynamic loading (desktop)
 

src/app/commands.rs

@@ -36,6 +36,7 @@ impl OpenCADStudio {
             && !matches!(
                 cmd,
                 "NEW" | "OPEN" | "EXIT" | "QUIT" | "REPORT" | "CHANGELOG" | "ABOUT"
+                    | "PLUGINS" | "PLUGINMANAGER"
             )
         {
             self.command_line
@@ -2675,6 +2676,10 @@ impl OpenCADStudio {
                 return Task::done(Message::AboutOpen);
             }
 
+            "PLUGINS" | "PLUGINMANAGER" => {
+                return Task::done(Message::PluginManagerOpen);
+            }
+
             "CHANGELOG" => {
                 let _ = open::that("https://github.com/HakanSeven12/OpenCADStudio/releases");
                 self.command_line.push_info("Opening release notes...");

src/app/mod.rs

@@ -292,6 +292,7 @@ pub(super) struct OpenCADStudio {
     color_pick_target: Option<ColorPickTarget>,
     shortcuts_window: Option<window::Id>,
     about_window: Option<window::Id>,
+    plugin_manager_window: Option<window::Id>,
     /// New-release notification window — opened on startup when the
     /// GitHub releases API reports a newer version than this build.
     update_notice_window: Option<window::Id>,
@@ -987,6 +988,10 @@ pub enum Message {
     // ── About window ────────────────────────────────────────────────────
     AboutOpen,
     AboutCopyInfo,
+    // ── Plugin Manager window ───────────────────────────────────────────
+    PluginManagerOpen,
+    #[allow(dead_code)]
+    PluginManagerClose,
     // ── Quick Select / Select Similar ───────────────────────────────────
     /// Extend the current selection with every entity in the active
     /// layout that matches a selected entity by (type, layer).
@@ -1402,6 +1407,7 @@ impl OpenCADStudio {
             color_pick_target: None,
             shortcuts_window: None,
             about_window: None,
+            plugin_manager_window: None,
             update_notice_window: None,
             assoc_prompt_window: None,
             default_assoc_prompted: false,
@@ -1712,6 +1718,9 @@ pub fn run() -> iced::Result {
         if Some(window_id) == state.about_window {
             return "About Open CAD Studio".into();
         }
+        if Some(window_id) == state.plugin_manager_window {
+            return "Plugin Manager".into();
+        }
         if Some(window_id) == state.update_notice_window {
             return "Update Available".into();
         }

src/app/update.rs

@@ -1640,6 +1640,9 @@ impl OpenCADStudio {
                     self.about_window = None;
                     self.ribbon.deactivate_tool_if("ABOUT");
                 }
+                if self.plugin_manager_window == Some(id) {
+                    self.plugin_manager_window = None;
+                }
                 if self.update_notice_window == Some(id) {
                     self.update_notice_window = None;
                 }
@@ -5394,6 +5397,28 @@ impl OpenCADStudio {
                 iced::clipboard::write(info)
             }
 
+            // ── Plugin Manager window ─────────────────────────────────────
+            Message::PluginManagerOpen => {
+                if let Some(id) = self.plugin_manager_window {
+                    return window::gain_focus(id);
+                }
+                let (id, task) = window::open(window::Settings {
+                    size: iced::Size::new(520.0, 460.0),
+                    resizable: true,
+                    level: window::Level::AlwaysOnTop,
+                    ..Default::default()
+                });
+                self.plugin_manager_window = Some(id);
+                task.map(|_| Message::Noop)
+            }
+            Message::PluginManagerClose => {
+                if let Some(id) = self.plugin_manager_window.take() {
+                    window::close(id)
+                } else {
+                    Task::none()
+                }
+            }
+
             Message::EnterViewport(handle) => {
                 let i = self.active_tab;
                 // Clear paper-space selection before entering model space.

src/app/view.rs

@@ -474,6 +474,9 @@ impl OpenCADStudio {
         if Some(window_id) == self.about_window {
             return crate::ui::about::view_window();
         }
+        if Some(window_id) == self.plugin_manager_window {
+            return crate::ui::plugin_manager::view_window(&crate::plugin::installed_manifests());
+        }
         if Some(window_id) == self.update_notice_window {
             let latest = self.update_notice_version.as_deref().unwrap_or("?");
             let body = self.update_notice_body.as_deref().unwrap_or("");
@@ -3743,6 +3746,7 @@ pub(super) fn start_page_view<'a>() -> Element<'a, Message> {
                 event: crate::modules::ModuleEvent::Command("CHANGELOG".to_string()),
             },
         ),
+        outline_btn("Plugins", Message::PluginManagerOpen),
         outline_btn("About", Message::AboutOpen),
     ]
     .spacing(12)

src/plugin/mod.rs

@@ -10,4 +10,4 @@ pub mod registry;
 
 pub use registry::all_ribbon_modules;
 pub(crate) use host::BuiltinPlugin;
-pub(crate) use registry::try_dispatch;
+pub(crate) use registry::{installed_manifests, try_dispatch};

src/plugin/registry.rs

@@ -1,6 +1,7 @@
 // Compile-time plugin registry via `inventory`.
 
 use super::host::{BuiltinPlugin, HostSession};
+use super::manifest::PluginManifest;
 use crate::app::OpenCADStudio;
 use crate::modules::{registry as core_registry, CadModule};
 
@@ -18,6 +19,15 @@ pub fn all_plugins() -> Vec<Box<dyn BuiltinPlugin>> {
         .collect()
 }
 
+/// Static manifest of every installed add-on, sorted by `ribbon_order` then id
+/// for a stable display. Used by the plugin manager window.
+pub fn installed_manifests() -> Vec<&'static PluginManifest> {
+    let mut manifests: Vec<&'static PluginManifest> =
+        all_plugins().iter().map(|p| p.manifest()).collect();
+    manifests.sort_by(|a, b| a.ribbon_order.cmp(&b.ribbon_order).then(a.id.cmp(b.id)));
+    manifests
+}
+
 /// Core ribbon tabs plus add-on tabs (sorted by `manifest.ribbon_order`).
 pub fn all_ribbon_modules() -> Vec<Box<dyn CadModule>> {
     let mut core = core_registry::all_modules();
@@ -61,6 +71,25 @@ mod tests {
         );
     }
 
+    #[test]
+    fn installed_manifests_lists_demo_plugin() {
+        let manifests = installed_manifests();
+        assert!(
+            manifests.iter().any(|m| m.id == "opencad.demo_plugin"),
+            "ids: {:?}",
+            manifests.iter().map(|m| m.id).collect::<Vec<_>>()
+        );
+        // Sorted by (ribbon_order, id) — verify non-decreasing order.
+        let mut prev: Option<(i32, &str)> = None;
+        for m in &manifests {
+            let key = (m.ribbon_order, m.id);
+            if let Some(p) = prev {
+                assert!(p <= key, "manifests not sorted: {p:?} then {key:?}");
+            }
+            prev = Some(key);
+        }
+    }
+
     #[test]
     fn addon_ribbon_tabs_merge_after_core() {
         let titles: Vec<&str> = all_ribbon_modules().iter().map(|m| m.title()).collect();

src/ui/mod.rs

@@ -17,6 +17,7 @@ pub mod open_progress;
 pub mod overlay;
 pub mod page_setup;
 pub mod plotstyle;
+pub mod plugin_manager;
 pub mod properties;
 pub mod ribbon;
 pub mod scale_popup;

src/ui/plugin_manager.rs

@@ -0,0 +1,146 @@
+//! Plugin Manager window — lists the add-ons compiled into this build.
+//!
+//! Phase-1 stub: read-only inventory of installed plugins (name, version, id,
+//! API level, description). Enable/disable and dynamic loading come with the
+//! phase-2 loader; see `docs/plugin-architecture.md`.
+
+use crate::app::Message;
+use crate::plugin::manifest::PluginManifest;
+use iced::widget::{column, container, row, scrollable, text, Space};
+use iced::{Background, Border, Color, Element, Fill, Theme};
+
+// Register the command names for autocomplete.
+inventory::submit!(crate::command::CommandRegistration {
+    names: &["PLUGINS", "PLUGINMANAGER"]
+});
+
+const BG: Color = Color {
+    r: 0.15,
+    g: 0.15,
+    b: 0.15,
+    a: 1.0,
+};
+const CARD: Color = Color {
+    r: 0.12,
+    g: 0.12,
+    b: 0.12,
+    a: 1.0,
+};
+const BORDER: Color = Color {
+    r: 0.30,
+    g: 0.30,
+    b: 0.30,
+    a: 1.0,
+};
+const DIM: Color = Color {
+    r: 0.55,
+    g: 0.55,
+    b: 0.55,
+    a: 1.0,
+};
+const ACCENT: Color = Color {
+    r: 0.30,
+    g: 0.62,
+    b: 0.95,
+    a: 1.0,
+};
+const WHITE: Color = Color {
+    r: 0.92,
+    g: 0.92,
+    b: 0.92,
+    a: 1.0,
+};
+
+fn badge<'a>(label: String) -> Element<'a, Message> {
+    container(text(label).size(11).color(WHITE))
+        .padding([2, 8])
+        .style(|_: &Theme| container::Style {
+            background: Some(Background::Color(Color {
+                r: 0.20,
+                g: 0.34,
+                b: 0.52,
+                a: 1.0,
+            })),
+            border: Border {
+                radius: 4.0.into(),
+                ..Default::default()
+            },
+            ..Default::default()
+        })
+        .into()
+}
+
+fn plugin_card<'a>(m: &PluginManifest) -> Element<'a, Message> {
+    let header = row![
+        text(m.name.to_string()).size(15).color(WHITE),
+        Space::new().width(Fill),
+        badge(format!("v{}", m.version)),
+        Space::new().width(8),
+        badge(format!("API {}", m.api_version.major)),
+    ]
+    .align_y(iced::Center);
+
+    let id_line = text(m.id.to_string()).size(11).color(ACCENT);
+    let desc = text(m.description.to_string()).size(12).color(DIM);
+
+    let mut body = column![header, id_line, desc].spacing(5);
+
+    if !m.command_prefixes.is_empty() {
+        body = body.push(
+            text(format!("Commands: {}", m.command_prefixes.join(", ")))
+                .size(11)
+                .color(DIM),
+        );
+    }
+
+    container(body.padding([12, 14]))
+        .width(Fill)
+        .style(|_: &Theme| container::Style {
+            background: Some(Background::Color(CARD)),
+            border: Border {
+                color: BORDER,
+                width: 1.0,
+                radius: 6.0.into(),
+            },
+            ..Default::default()
+        })
+        .into()
+}
+
+pub fn view_window<'a>(plugins: &[&'static PluginManifest]) -> Element<'a, Message> {
+    let title = text("Installed Plugins").size(20).color(WHITE);
+    let subtitle = text(format!(
+        "{} add-on{} compiled into this build",
+        plugins.len(),
+        if plugins.len() == 1 { "" } else { "s" }
+    ))
+    .size(12)
+    .color(DIM);
+
+    let body: Element<'_, Message> = if plugins.is_empty() {
+        container(text("No plugins installed.").size(13).color(DIM))
+            .padding(20)
+            .into()
+    } else {
+        let mut list = column![].spacing(10);
+        for m in plugins {
+            list = list.push(plugin_card(m));
+        }
+        scrollable(list.width(Fill)).height(Fill).into()
+    };
+
+    container(
+        column![title, subtitle, Space::new().height(12), body]
+            .spacing(4)
+            .padding(20)
+            .width(Fill)
+            .height(Fill),
+    )
+    .style(|_: &Theme| container::Style {
+        background: Some(Background::Color(BG)),
+        ..Default::default()
+    })
+    .width(Fill)
+    .height(Fill)
+    .into()
+}