feat: introduce GetConversationSummary RPC

Author: bolinfest

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

@@ -140,6 +140,10 @@ client_request_definitions! {
         params: NewConversationParams,
         response: NewConversationResponse,
     },
+    GetConversationSummary {
+        params: GetConversationSummaryParams,
+        response: GetConversationSummaryResponse,
+    },
     /// List recorded Codex conversations (rollouts) with optional pagination and search.
     ListConversations {
         params: ListConversationsParams,
@@ -315,6 +319,18 @@ pub struct ResumeConversationResponse {
     pub initial_messages: Option<Vec<EventMsg>>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct GetConversationSummaryParams {
+    pub rollout_path: PathBuf,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct GetConversationSummaryResponse {
+    pub summary: ConversationSummary,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 pub struct ListConversationsParams {

codex-rs/app-server/src/codex_message_processor.rs

@@ -21,6 +21,8 @@ use codex_app_server_protocol::ExecOneOffCommandResponse;
 use codex_app_server_protocol::FuzzyFileSearchParams;
 use codex_app_server_protocol::FuzzyFileSearchResponse;
 use codex_app_server_protocol::GetAccountRateLimitsResponse;
+use codex_app_server_protocol::GetConversationSummaryParams;
+use codex_app_server_protocol::GetConversationSummaryResponse;
 use codex_app_server_protocol::GetUserAgentResponse;
 use codex_app_server_protocol::GetUserSavedConfigResponse;
 use codex_app_server_protocol::GitDiffToRemoteResponse;
@@ -85,6 +87,7 @@ use codex_core::protocol::EventMsg;
 use codex_core::protocol::ExecApprovalRequestEvent;
 use codex_core::protocol::Op;
 use codex_core::protocol::ReviewDecision;
+use codex_core::read_head_records;
 use codex_login::ServerOptions as LoginServerOptions;
 use codex_login::ShutdownHandle;
 use codex_login::run_login_server;
@@ -98,6 +101,8 @@ use codex_protocol::user_input::UserInput as CoreInputItem;
 use codex_utils_json_to_toml::json_to_toml;
 use std::collections::HashMap;
 use std::ffi::OsStr;
+use std::io::Error as IoError;
+use std::path::Path;
 use std::path::PathBuf;
 use std::sync::Arc;
 use std::sync::atomic::AtomicBool;
@@ -170,6 +175,9 @@ impl CodexMessageProcessor {
                 // created before processing any subsequent messages.
                 self.process_new_conversation(request_id, params).await;
             }
+            ClientRequest::GetConversationSummary { request_id, params } => {
+                self.get_conversation_summary(request_id, params).await;
+            }
             ClientRequest::ListConversations { request_id, params } => {
                 self.handle_list_conversations(request_id, params).await;
             }
@@ -813,6 +821,39 @@ impl CodexMessageProcessor {
         }
     }
 
+    async fn get_conversation_summary(
+        &self,
+        request_id: RequestId,
+        params: GetConversationSummaryParams,
+    ) {
+        let GetConversationSummaryParams { rollout_path } = params;
+        let path = if rollout_path.is_relative() {
+            self.config.codex_home.join(&rollout_path)
+        } else {
+            rollout_path.clone()
+        };
+        let fallback_provider = self.config.model_provider_id.as_str();
+
+        match read_summary_from_rollout(&path, fallback_provider).await {
+            Ok(summary) => {
+                let response = GetConversationSummaryResponse { summary };
+                self.outgoing.send_response(request_id, response).await;
+            }
+            Err(err) => {
+                let error = JSONRPCErrorError {
+                    code: INTERNAL_ERROR_CODE,
+                    message: format!(
+                        "failed to load conversation summary from {}: {}",
+                        path.display(),
+                        err
+                    ),
+                    data: None,
+                };
+                self.outgoing.send_error(request_id, error).await;
+            }
+        }
+    }
+
     async fn handle_list_conversations(
         &self,
         request_id: RequestId,
@@ -1644,6 +1685,34 @@ async fn on_exec_approval_response(
     }
 }
 
+async fn read_summary_from_rollout(
+    path: &Path,
+    fallback_provider: &str,
+) -> std::io::Result<ConversationSummary> {
+    let head = read_head_records(path, 1).await?;
+
+    let Some(first) = head.first() else {
+        return Err(IoError::other(format!(
+            "rollout at {} is empty",
+            path.display()
+        )));
+    };
+
+    serde_json::from_value::<SessionMeta>(first.clone()).map_err(|_| {
+        IoError::other(format!(
+            "rollout at {} does not start with session metadata",
+            path.display()
+        ))
+    })?;
+
+    extract_conversation_summary(path.to_path_buf(), &head, fallback_provider).ok_or_else(|| {
+        IoError::other(format!(
+            "rollout at {} is missing a user message",
+            path.display()
+        ))
+    })
+}
+
 fn extract_conversation_summary(
     path: PathBuf,
     head: &[serde_json::Value],
@@ -1730,14 +1799,15 @@ mod tests {
         let summary =
             extract_conversation_summary(path.clone(), &head, "test-provider").expect("summary");
 
-        assert_eq!(summary.conversation_id, conversation_id);
-        assert_eq!(
-            summary.timestamp,
-            Some("2025-09-05T16:53:11.850Z".to_string())
-        );
-        assert_eq!(summary.path, path);
-        assert_eq!(summary.preview, "Count to 5");
-        assert_eq!(summary.model_provider, "test-provider");
+        let expected = ConversationSummary {
+            conversation_id,
+            timestamp,
+            path,
+            preview: "Count to 5".to_string(),
+            model_provider: "test-provider".to_string(),
+        };
+
+        assert_eq!(summary, expected);
         Ok(())
     }
 }

codex-rs/core/src/lib.rs

@@ -77,6 +77,7 @@ pub use rollout::find_conversation_path_by_id_str;
 pub use rollout::list::ConversationItem;
 pub use rollout::list::ConversationsPage;
 pub use rollout::list::Cursor;
+pub use rollout::list::read_head_records;
 mod function_tool;
 mod state;
 mod tasks;

codex-rs/core/src/rollout/list.rs

@@ -451,6 +451,14 @@ async fn read_head_and_tail(
     Ok(summary)
 }
 
+pub async fn read_head_records(
+    path: &Path,
+    head_limit: usize,
+) -> io::Result<Vec<serde_json::Value>> {
+    let summary = read_head_and_tail(path, head_limit, 0).await?;
+    Ok(summary.head)
+}
+
 async fn read_tail_records(
     path: &Path,
     max_records: usize,