Switch to uuid_v7 and tighten ConversationId usage (#3819)

Make sure conversations have a timestamp.

codex-rs/mcp-server/Cargo.toml

@@ -36,7 +36,7 @@ tokio = { version = "1", features = [
 toml = "0.9"
 tracing = { version = "0.1.41", features = ["log"] }
 tracing-subscriber = { version = "0.3", features = ["env-filter", "fmt"] }
-uuid = { version = "1", features = ["serde", "v4"] }
+uuid = { version = "1", features = ["serde", "v7"] }
 
 [dev-dependencies]
 assert_cmd = "2"

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

@@ -814,7 +814,7 @@ impl CodexMessageProcessor {
             return;
         };
 
-        let required_suffix = format!("{}.jsonl", conversation_id.0);
+        let required_suffix = format!("{conversation_id}.jsonl");
         let Some(file_name) = canonical_rollout_path.file_name().map(OsStr::to_owned) else {
             let error = JSONRPCErrorError {
                 code: INVALID_REQUEST_ERROR_CODE,
@@ -1414,13 +1414,13 @@ mod tests {
     #[test]
     fn extract_conversation_summary_prefers_plain_user_messages() {
         let conversation_id =
-            ConversationId(Uuid::parse_str("3f941c35-29b3-493b-b0a4-e25800d9aeb0").unwrap());
+            ConversationId::from_string("3f941c35-29b3-493b-b0a4-e25800d9aeb0").unwrap();
         let timestamp = Some("2025-09-05T16:53:11.850Z".to_string());
         let path = PathBuf::from("rollout.jsonl");
 
         let head = vec![
             json!({
-                "id": conversation_id.0,
+                "id": conversation_id.to_string(),
                 "timestamp": timestamp,
                 "cwd": "/",
                 "originator": "codex",

codex-rs/mcp-server/src/message_processor.rs

@@ -36,7 +36,6 @@ use serde_json::json;
 use std::sync::Arc;
 use tokio::sync::Mutex;
 use tokio::task;
-use uuid::Uuid;
 
 pub(crate) struct MessageProcessor {
     codex_message_processor: CodexMessageProcessor,
@@ -484,8 +483,8 @@ impl MessageProcessor {
                 return;
             }
         };
-        let conversation_id = match Uuid::parse_str(&conversation_id) {
-            Ok(id) => ConversationId::from(id),
+        let conversation_id = match ConversationId::from_string(&conversation_id) {
+            Ok(id) => id,
             Err(e) => {
                 tracing::error!("Failed to parse conversation_id: {e}");
                 let result = CallToolResult {

codex-rs/mcp-server/tests/suite/list_resume.rs

@@ -142,7 +142,7 @@ async fn test_list_and_resume_conversations() {
     } = to_response::<ResumeConversationResponse>(resume_resp)
         .expect("deserialize resumeConversation response");
     // conversation id should be a valid UUID
-    let _: uuid::Uuid = conversation_id.into();
+    assert!(!conversation_id.to_string().is_empty());
 }
 
 fn create_fake_rollout(codex_home: &Path, filename_ts: &str, meta_rfc3339: &str, preview: &str) {

codex-rs/mcp-server/tests/suite/send_message.rs

@@ -136,7 +136,7 @@ async fn test_send_message_session_not_found() {
         .expect("timeout")
         .expect("init");
 
-    let unknown = ConversationId(uuid::Uuid::new_v4());
+    let unknown = ConversationId::new();
     let req_id = mcp
         .send_send_user_message_request(SendUserMessageParams {
             conversation_id: unknown,