Add new thread items and rewire event parsing to use them (#5418)

1. Adds AgentMessage,  Reasoning,  WebSearch items.
2. Switches the ResponseItem parsing to use new items and then also emit
3. Removes user-item kind and filters out "special" (environment) user
items when returning to clients.

codex-rs/tui/src/chatwidget.rs

@@ -23,7 +23,6 @@ use codex_core::protocol::ExecApprovalRequestEvent;
 use codex_core::protocol::ExecCommandBeginEvent;
 use codex_core::protocol::ExecCommandEndEvent;
 use codex_core::protocol::ExitedReviewModeEvent;
-use codex_core::protocol::InputMessageKind;
 use codex_core::protocol::ListCustomPromptsResponseEvent;
 use codex_core::protocol::McpListToolsResponseEvent;
 use codex_core::protocol::McpToolCallBeginEvent;
@@ -1553,17 +1552,9 @@ impl ChatWidget {
     }
 
     fn on_user_message_event(&mut self, event: UserMessageEvent) {
-        match event.kind {
-            Some(InputMessageKind::EnvironmentContext)
-            | Some(InputMessageKind::UserInstructions) => {
-                // Skip XML‑wrapped context blocks in the transcript.
-            }
-            Some(InputMessageKind::Plain) | None => {
-                let message = event.message.trim();
-                if !message.is_empty() {
-                    self.add_to_history(history_cell::new_user_prompt(message.to_string()));
-                }
-            }
+        let message = event.message.trim();
+        if !message.is_empty() {
+            self.add_to_history(history_cell::new_user_prompt(message.to_string()));
         }
     }
 

codex-rs/tui/src/chatwidget/tests.rs

@@ -23,7 +23,6 @@ use codex_core::protocol::ExecCommandBeginEvent;
 use codex_core::protocol::ExecCommandEndEvent;
 use codex_core::protocol::ExitedReviewModeEvent;
 use codex_core::protocol::FileChange;
-use codex_core::protocol::InputMessageKind;
 use codex_core::protocol::Op;
 use codex_core::protocol::PatchApplyBeginEvent;
 use codex_core::protocol::PatchApplyEndEvent;
@@ -104,7 +103,6 @@ fn resumed_initial_messages_render_history() {
         initial_messages: Some(vec![
             EventMsg::UserMessage(UserMessageEvent {
                 message: "hello from user".to_string(),
-                kind: Some(InputMessageKind::Plain),
                 images: None,
             }),
             EventMsg::AgentMessage(AgentMessageEvent {

codex-rs/tui/src/resume_picker.rs

@@ -10,6 +10,7 @@ use codex_core::ConversationsPage;
 use codex_core::Cursor;
 use codex_core::INTERACTIVE_SESSION_SOURCES;
 use codex_core::RolloutRecorder;
+use codex_protocol::items::TurnItem;
 use color_eyre::eyre::Result;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;
@@ -30,10 +31,7 @@ use crate::text_formatting::truncate_text;
 use crate::tui::FrameRequester;
 use crate::tui::Tui;
 use crate::tui::TuiEvent;
-use codex_protocol::models::ContentItem;
 use codex_protocol::models::ResponseItem;
-use codex_protocol::protocol::InputMessageKind;
-use codex_protocol::protocol::USER_MESSAGE_BEGIN;
 
 const PAGE_SIZE: usize = 25;
 const LOAD_NEAR_THRESHOLD: usize = 5;
@@ -616,37 +614,8 @@ fn extract_timestamp(value: &serde_json::Value) -> Option<DateTime<Utc>> {
 fn preview_from_head(head: &[serde_json::Value]) -> Option<String> {
     head.iter()
         .filter_map(|value| serde_json::from_value::<ResponseItem>(value.clone()).ok())
-        .find_map(|item| match item {
-            ResponseItem::Message { content, .. } => {
-                // Find the actual user message (as opposed to user instructions or ide context)
-                let preview = content
-                    .into_iter()
-                    .filter_map(|content| match content {
-                        ContentItem::InputText { text }
-                            if matches!(
-                                InputMessageKind::from(("user", text.as_str())),
-                                InputMessageKind::Plain
-                            ) =>
-                        {
-                            // Strip ide context.
-                            let text = match text.find(USER_MESSAGE_BEGIN) {
-                                Some(idx) => {
-                                    text[idx + USER_MESSAGE_BEGIN.len()..].trim().to_string()
-                                }
-                                None => text,
-                            };
-                            Some(text)
-                        }
-                        _ => None,
-                    })
-                    .collect::<String>();
-
-                if preview.is_empty() {
-                    None
-                } else {
-                    Some(preview)
-                }
-            }
+        .find_map(|item| match codex_core::parse_turn_item(&item) {
+            Some(TurnItem::UserMessage(user)) => Some(user.message()),
             _ => None,
         })
 }
@@ -999,6 +968,19 @@ mod tests {
                 "role": "user",
                 "content": [
                     { "type": "input_text", "text": "<user_instructions>hi</user_instructions>" },
+                ]
+            }),
+            json!({
+                "type": "message",
+                "role": "user",
+                "content": [
+                    { "type": "input_text", "text": "<environment_context>...</environment_context>" },
+                ]
+            }),
+            json!({
+                "type": "message",
+                "role": "user",
+                "content": [
                     { "type": "input_text", "text": "real question" },
                     { "type": "input_image", "image_url": "ignored" }
                 ]