feat(tui): add usage overlay and sidebar for displaying usage statistics and tasks

feat(tui): implement status bar with connection and turn state indicators
feat(tui): create workflow panel for agent status and progress visualization
feat(web): introduce web frontend interface with static file serving
feat(ws): add WebSocket interface for real-time communication and session management

apps/domain/src/cms/app_config.rs

@@ -0,0 +1,127 @@
+//! Pure domain entity for application configuration.
+//!
+//! Defines `AppConfig`, `ProviderConfig`, and `ModelRole` — the data
+//! structures that describe which LLM providers are registered, which
+//! model roles exist, and which provider/model is the default.
+//!
+//! # Architecture
+//! These are pure data structures with **no I/O logic**. Load/save
+//! responsibilities live in `AppConfigRepository` (domain::repository).
+//!
+//! ## Data Flow
+//! 1. `AppConfig` is deserialised from `app_config.json` at startup
+//! 2. The HTTP handler layer calls `SettingsService::update_provider()`
+//!    to mutate the provider map
+//! 3. The modified `AppConfig` is serialised back to `app_config.json`
+
+use std::collections::HashMap;
+
+use serde::{Deserialize, Serialize};
+
+/// Top-level application configuration.
+///
+/// Holds the registry of configured LLM providers, named model roles
+/// (logical profiles mapping to a provider+model pair), and the default
+/// provider/model selection.
+///
+/// ## Fields
+/// - `providers` — map of provider name → connection details
+/// - `model_roles` — map of role name → provider/model/temperature
+/// - `default_provider` — the provider to use when none is specified
+/// - `default_model` — the model to use when none is specified
+/// - `default_context_window` — fallback context window size in tokens
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AppConfig {
+    pub providers: HashMap<String, ProviderConfig>,
+    pub model_roles: HashMap<String, ModelRole>,
+    pub default_provider: String,
+    pub default_model: String,
+    pub default_context_window: u32,
+}
+
+/// Connection details for a single LLM provider endpoint.
+///
+/// ## Fields
+/// - `api_base` — base URL for the provider API
+/// - `api_key_env` — optional environment variable name holding the API key
+/// - `default_model` — optional default model name for this provider
+/// - `default_api_key` — optional inline API key (less secure than env var)
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ProviderConfig {
+    pub api_base: String,
+    pub api_key_env: Option<String>,
+    pub default_model: Option<String>,
+    pub default_api_key: Option<String>,
+}
+
+/// A named model role mapping to a specific provider/model with parameters.
+///
+/// Roles allow the UI to present logical profiles (e.g. "fast", "reasoning")
+/// that abstract over concrete provider+model strings.
+///
+/// ## Fields
+/// - `provider` — which provider serves this role
+/// - `model` — which model to use for this role
+/// - `max_tokens` — optional maximum output token limit
+/// - `context_window` — optional context window override
+/// - `temperature` — optional generation temperature
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ModelRole {
+    pub provider: String,
+    pub model: String,
+    pub max_tokens: Option<u32>,
+    pub context_window: Option<u32>,
+    pub temperature: Option<f32>,
+}
+
+/// Returns the default AppConfig with built-in "zen" and "router" providers.
+impl Default for AppConfig {
+    /// Construct an AppConfig with the default "zen" and "router" providers.
+    ///
+    /// ## Defaults
+    /// - Zen provider: `deepseek-v4-flash-free` model
+    /// - Router provider: `claude-opus-4-8` model
+    /// - Default role: "default" → zen / deepseek-v4-flash-free, temp 0.7
+    /// - `default_context_window`: 256,000 tokens
+    fn default() -> Self {
+        let mut providers = HashMap::new();
+        providers.insert(
+            "zen".to_string(),
+            ProviderConfig {
+                api_base: "https://opencode.ai/zen/v1".to_string(),
+                api_key_env: Some("API_KEY".to_string()),
+                default_model: Some("deepseek-v4-flash-free".to_string()),
+                default_api_key: None,
+            },
+        );
+        providers.insert(
+            "router".to_string(),
+            ProviderConfig {
+                api_base: "https://9router.asepharyana.my.id/v1".to_string(),
+                api_key_env: Some("ROUTER_API_KEY".to_string()),
+                default_model: Some("claude-opus-4-8".to_string()),
+                default_api_key: None,
+            },
+        );
+
+        let mut model_roles = HashMap::new();
+        model_roles.insert(
+            "default".to_string(),
+            ModelRole {
+                provider: "zen".to_string(),
+                model: "deepseek-v4-flash-free".to_string(),
+                max_tokens: None,
+                context_window: None,
+                temperature: Some(0.7),
+            },
+        );
+
+        Self {
+            providers,
+            model_roles,
+            default_provider: "zen".to_string(),
+            default_model: "deepseek-v4-flash-free".to_string(),
+            default_context_window: 256_000,
+        }
+    }
+}