feat(tui2): copy tui crate and normalize snapshots (#7833)

Introduce a full codex-tui source snapshot under the new codex-tui2
crate so viewport work can be replayed in isolation.

This change copies the entire codex-rs/tui/src tree into
codex-rs/tui2/src in one atomic step, rather than piecemeal, to keep
future diffs vs the original viewport bookmark easy to reason about.

The goal is for codex-tui2 to render identically to the existing TUI
behind the `features.tui2` flag while we gradually port the
viewport/history commits from the joshka/viewport bookmark onto this
forked tree.

While on this baseline change, we also ran the codex-tui2 snapshot test
suite and accepted all insta snapshots for the new crate, so the
snapshot files now use the codex-tui2 naming scheme and encode the
unmodified legacy TUI behavior. This keeps later viewport commits
focused on intentional behavior changes (and their snapshots) rather
than on mechanical snapshot renames.

codex-rs/tui2/src/public_widgets/composer_input.rs

@@ -0,0 +1,128 @@
+//! Public wrapper around the internal ChatComposer for simple, reusable text input.
+//!
+//! This exposes a minimal interface suitable for other crates (e.g.,
+//! codex-cloud-tasks) to reuse the mature composer behavior: multi-line input,
+//! paste heuristics, Enter-to-submit, and Shift+Enter for newline.
+
+use crossterm::event::KeyEvent;
+use ratatui::buffer::Buffer;
+use ratatui::layout::Rect;
+use std::time::Duration;
+
+use crate::app_event::AppEvent;
+use crate::app_event_sender::AppEventSender;
+use crate::bottom_pane::ChatComposer;
+use crate::bottom_pane::InputResult;
+use crate::render::renderable::Renderable;
+
+/// Action returned from feeding a key event into the ComposerInput.
+pub enum ComposerAction {
+    /// The user submitted the current text (typically via Enter). Contains the submitted text.
+    Submitted(String),
+    /// No submission occurred; UI may need to redraw if `needs_redraw()` returned true.
+    None,
+}
+
+/// A minimal, public wrapper for the internal `ChatComposer` that behaves as a
+/// reusable text input field with submit semantics.
+pub struct ComposerInput {
+    inner: ChatComposer,
+    _tx: tokio::sync::mpsc::UnboundedSender<AppEvent>,
+    rx: tokio::sync::mpsc::UnboundedReceiver<AppEvent>,
+}
+
+impl ComposerInput {
+    /// Create a new composer input with a neutral placeholder.
+    pub fn new() -> Self {
+        let (tx, rx) = tokio::sync::mpsc::unbounded_channel();
+        let sender = AppEventSender::new(tx.clone());
+        // `enhanced_keys_supported=true` enables Shift+Enter newline hint/behavior.
+        let inner = ChatComposer::new(true, sender, true, "Compose new task".to_string(), false);
+        Self { inner, _tx: tx, rx }
+    }
+
+    /// Returns true if the input is empty.
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+
+    /// Clear the input text.
+    pub fn clear(&mut self) {
+        self.inner.set_text_content(String::new());
+    }
+
+    /// Feed a key event into the composer and return a high-level action.
+    pub fn input(&mut self, key: KeyEvent) -> ComposerAction {
+        let action = match self.inner.handle_key_event(key).0 {
+            InputResult::Submitted(text) => ComposerAction::Submitted(text),
+            _ => ComposerAction::None,
+        };
+        self.drain_app_events();
+        action
+    }
+
+    pub fn handle_paste(&mut self, pasted: String) -> bool {
+        let handled = self.inner.handle_paste(pasted);
+        self.drain_app_events();
+        handled
+    }
+
+    /// Override the footer hint items displayed under the composer.
+    /// Each tuple is rendered as "<key> <label>", with keys styled.
+    pub fn set_hint_items(&mut self, items: Vec<(impl Into<String>, impl Into<String>)>) {
+        let mapped: Vec<(String, String)> = items
+            .into_iter()
+            .map(|(k, v)| (k.into(), v.into()))
+            .collect();
+        self.inner.set_footer_hint_override(Some(mapped));
+    }
+
+    /// Clear any previously set custom hint items and restore the default hints.
+    pub fn clear_hint_items(&mut self) {
+        self.inner.set_footer_hint_override(None);
+    }
+
+    /// Desired height (in rows) for a given width.
+    pub fn desired_height(&self, width: u16) -> u16 {
+        self.inner.desired_height(width)
+    }
+
+    /// Compute the on-screen cursor position for the given area.
+    pub fn cursor_pos(&self, area: Rect) -> Option<(u16, u16)> {
+        self.inner.cursor_pos(area)
+    }
+
+    /// Render the input into the provided buffer at `area`.
+    pub fn render_ref(&self, area: Rect, buf: &mut Buffer) {
+        self.inner.render(area, buf);
+    }
+
+    /// Return true if a paste-burst detection is currently active.
+    pub fn is_in_paste_burst(&self) -> bool {
+        self.inner.is_in_paste_burst()
+    }
+
+    /// Flush a pending paste-burst if the inter-key timeout has elapsed.
+    /// Returns true if text changed and a redraw is warranted.
+    pub fn flush_paste_burst_if_due(&mut self) -> bool {
+        let flushed = self.inner.flush_paste_burst_if_due();
+        self.drain_app_events();
+        flushed
+    }
+
+    /// Recommended delay to schedule the next micro-flush frame while a
+    /// paste-burst is active.
+    pub fn recommended_flush_delay() -> Duration {
+        crate::bottom_pane::ChatComposer::recommended_paste_flush_delay()
+    }
+
+    fn drain_app_events(&mut self) {
+        while self.rx.try_recv().is_ok() {}
+    }
+}
+
+impl Default for ComposerInput {
+    fn default() -> Self {
+        Self::new()
+    }
+}

codex-rs/tui2/src/public_widgets/mod.rs

@@ -0,0 +1 @@
+pub mod composer_input;