first pass of merging in warp (doesn't build)

crates/warp_tui/src/input/kill_buffer.rs

@@ -0,0 +1,44 @@
+/// A single-entry kill buffer for the TUI input view.
+///
+/// Stores the last text killed by `Ctrl+K`, `Ctrl+U`, `Ctrl+W`, or `Alt+D`.
+/// `Ctrl+Y` yanks (pastes) the stored text back into the input.
+///
+/// This is intentionally simple — a kill ring (multi-entry yank cycle) is
+/// listed as a follow-up in `specs/tui-input-view/TECH.md`.
+#[derive(Debug, Default)]
+pub struct KillBuffer {
+    content: String,
+}
+
+impl KillBuffer {
+    /// Store `text` as the killed content, replacing any previous entry.
+    pub fn kill(&mut self, text: impl Into<String>) {
+        self.content = text.into();
+    }
+
+    /// Append `text` to the current kill buffer content.
+    /// Used when multiple consecutive kills are combined (e.g. `Ctrl+K` at
+    /// the end of one line followed immediately by another `Ctrl+K`).
+    pub fn kill_append(&mut self, text: impl Into<String>) {
+        self.content.push_str(&text.into());
+    }
+
+    /// Return the killed text for yanking, if any.
+    pub fn yank(&self) -> Option<&str> {
+        if self.content.is_empty() {
+            None
+        } else {
+            Some(&self.content)
+        }
+    }
+
+    /// Return whether the kill buffer is empty.
+    pub fn is_empty(&self) -> bool {
+        self.content.is_empty()
+    }
+
+    /// Clear the kill buffer.
+    pub fn clear(&mut self) {
+        self.content.clear();
+    }
+}