[app-server] Add a method to list experimental features. (#10721)

- [x] Add a method to list experimental features.

codex-rs/app-server-protocol/src/protocol/v2.rs

@@ -1043,6 +1043,46 @@ pub struct CollaborationModeListResponse {
     pub data: Vec<CollaborationModeMask>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ExperimentalFeatureListParams {
+    /// Opaque pagination cursor returned by a previous call.
+    #[ts(optional = nullable)]
+    pub cursor: Option<String>,
+    /// Optional page size; defaults to a reasonable server-side value.
+    #[ts(optional = nullable)]
+    pub limit: Option<u32>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ExperimentalFeature {
+    /// Stable key used in config.toml and CLI flag toggles.
+    pub flag_name: String,
+    /// User-facing display name shown in the experimental features UI.
+    pub display_name: String,
+    /// Short summary describing what the feature does.
+    pub description: String,
+    /// Announcement copy shown to users when the feature is introduced.
+    pub announcement: String,
+    /// Whether this feature is currently enabled in the loaded config.
+    pub enabled: bool,
+    /// Whether this feature is enabled by default.
+    pub default_enabled: bool,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ExperimentalFeatureListResponse {
+    pub data: Vec<ExperimentalFeature>,
+    /// Opaque cursor to pass to the next call to continue after the last item.
+    /// If None, there are no more items to return.
+    pub next_cursor: Option<String>,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]