feat: add resume logs when doing /new (openai#6660)

<img width="769" height="803" alt="Screenshot 2025-11-14 at 10 25 49"
src="https://github.com/user-attachments/assets/12fbc21e-cab9-4d0a-a484-1aeb60219f96"
/>

Author: jif-oai

codex-rs/tui/src/app.rs

@@ -24,6 +24,7 @@ use codex_core::ConversationManager;
 use codex_core::config::Config;
 use codex_core::config::edit::ConfigEditsBuilder;
 use codex_core::model_family::find_family_for_model;
+use codex_core::protocol::FinalOutput;
 use codex_core::protocol::SessionSource;
 use codex_core::protocol::TokenUsage;
 use codex_core::protocol_config_types::ReasoningEffort as ReasoningEffortConfig;
@@ -54,6 +55,29 @@ pub struct AppExitInfo {
     pub update_action: Option<UpdateAction>,
 }
 
+fn session_summary(
+    token_usage: TokenUsage,
+    conversation_id: Option<ConversationId>,
+) -> Option<SessionSummary> {
+    if token_usage.is_zero() {
+        return None;
+    }
+
+    let usage_line = FinalOutput::from(token_usage).to_string();
+    let resume_command =
+        conversation_id.map(|conversation_id| format!("codex resume {conversation_id}"));
+    Some(SessionSummary {
+        usage_line,
+        resume_command,
+    })
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct SessionSummary {
+    usage_line: String,
+    resume_command: Option<String>,
+}
+
 fn should_show_model_migration_prompt(
     current_model: &str,
     target_model: &str,
@@ -365,6 +389,10 @@ impl App {
     async fn handle_event(&mut self, tui: &mut tui::Tui, event: AppEvent) -> Result<bool> {
         match event {
             AppEvent::NewSession => {
+                let summary = session_summary(
+                    self.chat_widget.token_usage(),
+                    self.chat_widget.conversation_id(),
+                );
                 let init = crate::chatwidget::ChatWidgetInit {
                     config: self.config.clone(),
                     frame_requester: tui.frame_requester(),
@@ -376,6 +404,14 @@ impl App {
                     feedback: self.feedback.clone(),
                 };
                 self.chat_widget = ChatWidget::new(init, self.server.clone());
+                if let Some(summary) = summary {
+                    let mut lines: Vec<Line<'static>> = vec![summary.usage_line.clone().into()];
+                    if let Some(command) = summary.resume_command {
+                        let spans = vec!["To continue this session, run ".into(), command.cyan()];
+                        lines.push(spans.into());
+                    }
+                    self.chat_widget.add_plain_history_lines(lines);
+                }
                 tui.frame_requester().schedule_frame();
             }
             AppEvent::InsertHistoryCell(cell) => {
@@ -970,4 +1006,31 @@ mod tests {
         assert_eq!(nth, 1);
         assert_eq!(prefill, "follow-up (edited)");
     }
+
+    #[test]
+    fn session_summary_skip_zero_usage() {
+        assert!(session_summary(TokenUsage::default(), None).is_none());
+    }
+
+    #[test]
+    fn session_summary_includes_resume_hint() {
+        let usage = TokenUsage {
+            input_tokens: 10,
+            output_tokens: 2,
+            total_tokens: 12,
+            ..Default::default()
+        };
+        let conversation =
+            ConversationId::from_string("123e4567-e89b-12d3-a456-426614174000").unwrap();
+
+        let summary = session_summary(usage, Some(conversation)).expect("summary");
+        assert_eq!(
+            summary.usage_line,
+            "Token usage: total=12 input=10 output=2"
+        );
+        assert_eq!(
+            summary.resume_command,
+            Some("codex resume 123e4567-e89b-12d3-a456-426614174000".to_string())
+        );
+    }
 }

codex-rs/tui/src/chatwidget.rs

@@ -85,6 +85,7 @@ use crate::history_cell;
 use crate::history_cell::AgentMessageCell;
 use crate::history_cell::HistoryCell;
 use crate::history_cell::McpToolCallCell;
+use crate::history_cell::PlainHistoryCell;
 use crate::markdown::append_markdown;
 #[cfg(target_os = "windows")]
 use crate::onboarding::WSL_INSTRUCTIONS;
@@ -2462,6 +2463,11 @@ impl ChatWidget {
         self.request_redraw();
     }
 
+    pub(crate) fn add_plain_history_lines(&mut self, lines: Vec<Line<'static>>) {
+        self.add_boxed_history(Box::new(PlainHistoryCell::new(lines)));
+        self.request_redraw();
+    }
+
     pub(crate) fn add_error_message(&mut self, message: String) {
         self.add_to_history(history_cell::new_error_event(message));
         self.request_redraw();