Initial implementation of /init (#1822)

Basic /init command that appends an instruction to create AGENTS.md to
the conversation history.

codex-rs/tui/src/app.rs

@@ -300,6 +300,13 @@ impl App<'_> {
                         self.app_state = AppState::Chat { widget: new_widget };
                         self.app_event_tx.send(AppEvent::RequestRedraw);
                     }
+                    SlashCommand::Init => {
+                        // Guard: do not run if a task is active.
+                        if let AppState::Chat { widget } = &mut self.app_state {
+                            const INIT_PROMPT: &str = include_str!("../../../INIT.md");
+                            widget.submit_text_message(INIT_PROMPT.to_string());
+                        }
+                    }
                     SlashCommand::Compact => {
                         if let AppState::Chat { widget } = &mut self.app_state {
                             widget.clear_token_usage();

codex-rs/tui/src/bottom_pane/chat_composer.rs

@@ -729,6 +729,7 @@ impl WidgetRef for &ChatComposer {
 
 #[cfg(test)]
 mod tests {
+    use crate::app_event::AppEvent;
     use crate::bottom_pane::AppEventSender;
     use crate::bottom_pane::ChatComposer;
     use crate::bottom_pane::InputResult;
@@ -1004,6 +1005,49 @@ mod tests {
         }
     }
 
+    #[test]
+    fn slash_init_dispatches_command_and_does_not_submit_literal_text() {
+        use crossterm::event::KeyCode;
+        use crossterm::event::KeyEvent;
+        use crossterm::event::KeyModifiers;
+        use std::sync::mpsc::TryRecvError;
+
+        let (tx, rx) = std::sync::mpsc::channel();
+        let sender = AppEventSender::new(tx);
+        let mut composer = ChatComposer::new(true, sender, false);
+
+        // Type the slash command.
+        for ch in [
+            '/', 'i', 'n', 'i', 't', // "/init"
+        ] {
+            let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Char(ch), KeyModifiers::NONE));
+        }
+
+        // Press Enter to dispatch the selected command.
+        let (result, _needs_redraw) =
+            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
+
+        // When a slash command is dispatched, the composer should not submit
+        // literal text and should clear its textarea.
+        match result {
+            InputResult::None => {}
+            InputResult::Submitted(text) => {
+                panic!("expected command dispatch, but composer submitted literal text: {text}")
+            }
+        }
+        assert!(composer.textarea.is_empty(), "composer should be cleared");
+
+        // Verify a DispatchCommand event for the "init" command was sent.
+        match rx.try_recv() {
+            Ok(AppEvent::DispatchCommand(cmd)) => {
+                assert_eq!(cmd.command(), "init");
+            }
+            Ok(_other) => panic!("unexpected app event"),
+            Err(TryRecvError::Empty) => panic!("expected a DispatchCommand event for '/init'"),
+            Err(TryRecvError::Disconnected) => panic!("app event channel disconnected"),
+        }
+    }
+
     #[test]
     fn test_multiple_pastes_submission() {
         use crossterm::event::KeyCode;

codex-rs/tui/src/bottom_pane/command_popup.rs

@@ -188,3 +188,38 @@ impl WidgetRef for CommandPopup {
         table.render(area, buf);
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn filter_includes_init_when_typing_prefix() {
+        let mut popup = CommandPopup::new();
+        // Simulate the composer line starting with '/in' so the popup filters
+        // matching commands by prefix.
+        popup.on_composer_text_change("/in".to_string());
+
+        // Access the filtered list via the selected command and ensure that
+        // one of the matches is the new "init" command.
+        let matches = popup.filtered_commands();
+        assert!(
+            matches.iter().any(|cmd| cmd.command() == "init"),
+            "expected '/init' to appear among filtered commands"
+        );
+    }
+
+    #[test]
+    fn selecting_init_by_exact_match() {
+        let mut popup = CommandPopup::new();
+        popup.on_composer_text_change("/init".to_string());
+
+        // When an exact match exists, the selected command should be that
+        // command by default.
+        let selected = popup.selected_command();
+        match selected {
+            Some(cmd) => assert_eq!(cmd.command(), "init"),
+            None => panic!("expected a selected command for exact match"),
+        }
+    }
+}

codex-rs/tui/src/chatwidget.rs

@@ -575,6 +575,16 @@ impl ChatWidget<'_> {
         }
     }
 
+    /// Programmatically submit a user text message as if typed in the
+    /// composer. The text will be added to conversation history and sent to
+    /// the agent.
+    pub(crate) fn submit_text_message(&mut self, text: String) {
+        if text.is_empty() {
+            return;
+        }
+        self.submit_user_message(text.into());
+    }
+
     pub(crate) fn token_usage(&self) -> &TokenUsage {
         &self.token_usage
     }

codex-rs/tui/src/slash_command.rs

@@ -13,6 +13,7 @@ pub enum SlashCommand {
     // DO NOT ALPHA-SORT! Enum order is presentation order in the popup, so
     // more frequently used commands should be listed first.
     New,
+    Init,
     Compact,
     Diff,
     Status,
@@ -26,6 +27,7 @@ impl SlashCommand {
     pub fn description(self) -> &'static str {
         match self {
             SlashCommand::New => "Start a new chat",
+            SlashCommand::Init => "Create an AGENTS.md file with instructions for Codex.",
             SlashCommand::Compact => "Compact the chat history",
             SlashCommand::Quit => "Exit the application",
             SlashCommand::Diff => "Show git diff (including untracked files)",