feat: implement model management commands and overlays for enhanced user interaction

src/app/runtime/actions/mod.rs

@@ -60,6 +60,14 @@ pub enum Action {
         name: String,
         command: String,
     },
+    ModelList,
+    ModelUse {
+        provider: String,
+    },
+    ModelAdd {
+        name: String,
+        base_url: String,
+    },
 }
 
 pub fn apply_action(state: &mut AppStateRest, action: Action) {
@@ -184,6 +192,44 @@ pub fn apply_action(state: &mut AppStateRest, action: Action) {
                 }
             }
         }
+        Action::ModelList => {
+            state.misc.selected_index = 0;
+            state.misc.overlay = Overlay::ModelSelector;
+            state.dirty = true;
+        }
+        Action::ModelUse { provider } => {
+            if state.app_config.providers.contains_key(&provider) {
+                let default_model = state.app_config.providers[&provider]
+                    .default_model.clone()
+                    .unwrap_or_else(|| "claude-opus-4-8".to_string());
+                state.settings.provider = provider.clone();
+                state.settings.model = default_model;
+                let _ = state.settings.save();
+                state.push_toast(Toast::new(ToastKind::Success,
+                    format!("Switched to provider '{}' (model: {})", provider, state.settings.model)));
+            } else {
+                state.push_toast(Toast::new(ToastKind::Error,
+                    format!("Unknown provider '{}'. Use /model ls to see available ones.", provider)));
+            }
+            state.dirty = true;
+        }
+        Action::ModelAdd { name, base_url } => {
+            if base_url.is_empty() {
+                state.push_toast(Toast::new(ToastKind::Error, "Usage: /model add <name> <base_url>".to_string()));
+            } else {
+                let cfg = crate::model::app_config::ProviderConfig {
+                    api_base: base_url.clone(),
+                    api_key_env: None,
+                    default_model: Some("claude-opus-4-8".to_string()),
+                };
+                state.app_config.providers.insert(name.clone(), cfg);
+                state.push_toast(Toast::new(ToastKind::Success,
+                    format!("Added provider '{}' at {}", name, base_url)));
+                state.push_toast(Toast::new(ToastKind::Info,
+                    "Use /model use <name> to switch, or /edit app_config.json to configure further".to_string()));
+                state.dirty = true;
+            }
+        }
         Action::CloseOverlay => {
             // If the overlay is the Editor, dismiss it properly first
             if state.misc.overlay == Overlay::Editor {