feat: add APIs to list and download public remote skills (#10448)

Add API to list / download from remote public skills

codex-rs/protocol/src/protocol.rs

@@ -269,6 +269,15 @@ pub enum Op {
         force_reload: bool,
     },
 
+    /// Request the list of remote skills available via ChatGPT sharing.
+    ListRemoteSkills,
+
+    /// Download a remote skill by id into the local skills cache.
+    DownloadRemoteSkill {
+        hazelnut_id: String,
+        is_preload: bool,
+    },
+
     /// Request the agent to summarize the current conversation context.
     /// The agent will use its existing context (either conversation history or previous response id)
     /// to generate a summary which will be returned as an AgentMessage event.
@@ -822,6 +831,12 @@ pub enum EventMsg {
     /// List of skills available to the agent.
     ListSkillsResponse(ListSkillsResponseEvent),
 
+    /// List of remote skills available to the agent.
+    ListRemoteSkillsResponse(ListRemoteSkillsResponseEvent),
+
+    /// Remote skill downloaded to local cache.
+    RemoteSkillDownloaded(RemoteSkillDownloadedEvent),
+
     /// Notification that skill data may have been updated and clients may want to reload.
     SkillsUpdateAvailable,
 
@@ -2127,6 +2142,27 @@ pub struct ListSkillsResponseEvent {
     pub skills: Vec<SkillsListEntry>,
 }
 
+#[derive(Debug, Clone, Deserialize, Serialize, JsonSchema, TS)]
+pub struct RemoteSkillSummary {
+    pub id: String,
+    pub name: String,
+    pub description: String,
+}
+
+/// Response payload for `Op::ListRemoteSkills`.
+#[derive(Debug, Clone, Deserialize, Serialize, JsonSchema, TS)]
+pub struct ListRemoteSkillsResponseEvent {
+    pub skills: Vec<RemoteSkillSummary>,
+}
+
+/// Response payload for `Op::DownloadRemoteSkill`.
+#[derive(Debug, Clone, Deserialize, Serialize, JsonSchema, TS)]
+pub struct RemoteSkillDownloadedEvent {
+    pub id: String,
+    pub name: String,
+    pub path: PathBuf,
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, JsonSchema, TS)]
 #[serde(rename_all = "snake_case")]
 #[ts(rename_all = "snake_case")]