[codex] Add user input client ids (#24653)

## Summary

Adds an optional `clientId` field to app-server v2 `UserInput` and
carries it through the core `UserInput` model so clients can correlate
echoed user input items without relying on payload equality.

## Details

- Adds `client_id: Option<String>` to core `UserInput` variants.
- Exposes the v2 app-server field as `clientId` on the wire and in
generated TypeScript.
- Preserves the id when converting between app-server v2 and core
protocol types.
- Regenerates app-server schema fixtures.

## Validation

- `just fmt`
- `just write-app-server-schema`
- `cargo test -p codex-app-server-protocol`
- `cargo test -p codex-protocol`
- `just fix -p codex-app-server-protocol`
- `just fix -p codex-protocol`
- `git diff --check`

codex-rs/app-server/src/request_processors/thread_processor_tests.rs

@@ -213,6 +213,7 @@ mod thread_processor_behavior_tests {
     fn thread_turns_list_merges_in_progress_active_turn_before_agent_status_running() {
         let persisted_items = vec![RolloutItem::EventMsg(EventMsg::UserMessage(
             codex_protocol::protocol::UserMessageEvent {
+                client_id: None,
                 message: "persisted".to_string(),
                 images: None,
                 local_images: Vec::new(),
@@ -224,6 +225,7 @@ mod thread_processor_behavior_tests {
             id: "live-turn".to_string(),
             items: vec![ThreadItem::UserMessage {
                 id: "live-user-message".to_string(),
+                client_id: None,
                 content: vec![V2UserInput::Text {
                     text: "live".to_string(),
                     text_elements: Vec::new(),

codex-rs/app-server/src/request_processors/token_usage_replay.rs

@@ -148,6 +148,7 @@ mod tests {
     fn token_usage_history() -> Vec<RolloutItem> {
         vec![
             RolloutItem::EventMsg(EventMsg::UserMessage(UserMessageEvent {
+                client_id: None,
                 message: "first turn".to_string(),
                 images: None,
                 local_images: Vec::new(),
@@ -164,6 +165,7 @@ mod tests {
                 rate_limits: None,
             })),
             RolloutItem::EventMsg(EventMsg::UserMessage(UserMessageEvent {
+                client_id: None,
                 message: "second turn".to_string(),
                 images: None,
                 local_images: Vec::new(),

codex-rs/app-server/src/request_processors/turn_processor.rs

@@ -416,6 +416,7 @@ impl TurnRequestProcessor {
             .into_iter()
             .map(V2UserInput::into_core)
             .collect();
+        let client_user_message_id = params.client_user_message_id;
         let additional_context = map_additional_context(params.additional_context);
         let turn_has_input = !mapped_items.is_empty();
         let thread_settings = self
@@ -448,8 +449,12 @@ impl TurnRequestProcessor {
             additional_context,
             thread_settings,
         };
-        let turn_id = self
-            .submit_core_op(&request_id, thread.as_ref(), turn_op)
+        let turn_id = thread
+            .submit_user_input_with_client_user_message_id(
+                turn_op,
+                self.request_trace_context(&request_id).await,
+                client_user_message_id,
+            )
             .await
             .map_err(|err| {
                 let error = internal_error(format!("failed to start turn: {err}"));
@@ -780,6 +785,7 @@ impl TurnRequestProcessor {
                 mapped_items,
                 additional_context,
                 Some(&params.expected_turn_id),
+                params.client_user_message_id,
                 params.responsesapi_client_metadata,
             )
             .await
@@ -989,6 +995,7 @@ impl TurnRequestProcessor {
         } else {
             vec![ThreadItem::UserMessage {
                 id: turn_id.clone(),
+                client_id: None,
                 content: vec![V2UserInput::Text {
                     text: display_text.to_string(),
                     // Review prompt display text is synthesized; no UI element ranges to preserve.