feat: switch input source during prefix mode (#434)

On macOS, opt-in under [experimental], temporarily switch the host input
source to the current ASCII-capable layout while prefix mode is active so
prefix commands register even when a CJK IME is composing, then restore the
previous input source when prefix mode exits or is cancelled. No-op when the
current source is already ASCII-capable, on non-macOS platforms, or when any
input source call fails. Pane text input is unaffected.

Also pin next_resize_poll in next_loop_deadline_includes_selection_autoscroll_deadline
so the selection autoscroll deadline stays the earliest; the default resize
poll could otherwise beat it and flake the assertion.

refs #400

Co-authored-by: Can Celik <ogulcancelik@gmail.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/src/app/state.rs b/src/app/state.rs
index dd1b167e..a25c7c5e 100644
--- a/src/app/state.rs
+++ b/src/app/state.rs
@@ -867,6 +867,34 @@ impl SettingsSection {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum ExperimentSetting {
+    PaneHistory,
+    SwitchAsciiInputSourceInPrefix,
+}
+
+impl ExperimentSetting {
+    pub(crate) const ALL: [Self; 2] = [Self::PaneHistory, Self::SwitchAsciiInputSourceInPrefix];
+
+    pub(crate) fn label(self) -> &'static str {
+        match self {
+            Self::PaneHistory => "pane screen history",
+            Self::SwitchAsciiInputSourceInPrefix => {
+                "switch to ascii input source in prefix (macOS)"
+            }
+        }
+    }
+
+    pub(crate) fn enabled(self, state: &AppState) -> bool {
+        match self {
+            Self::PaneHistory => state.pane_history_persistence_enabled(),
+            Self::SwitchAsciiInputSourceInPrefix => {
+                state.switch_ascii_input_source_in_prefix_enabled()
+            }
+        }
+    }
+}
+
 /// All built-in theme names in display order.
 pub const THEME_NAMES: &[&str] = &[
     "catppuccin",
@@ -1268,6 +1296,11 @@ pub struct AppState {
     pub cjk_ime_agents: Vec<crate::detect::Agent>,
     /// DECSCUSR shape parameter (1–6) for the IME anchor cursor.
     pub cjk_ime_cursor_shape: u8,
+    /// While prefix mode is active, switch the macOS host input source to an
+    /// ASCII-capable layout so prefix commands register as ASCII even when a
+    /// CJK IME is active. macOS only; a no-op elsewhere. See
+    /// `[experimental] switch_ascii_input_source_in_prefix`.
+    pub switch_ascii_input_source_in_prefix: bool,
     pub kitty_graphics_enabled: bool,
     pub default_shell: String,
     pub shell_mode: crate::config::ShellModeConfig,
@@ -1327,6 +1360,10 @@ impl AppState {
         self.pane_history_persistence
     }
 
+    pub fn switch_ascii_input_source_in_prefix_enabled(&self) -> bool {
+        self.switch_ascii_input_source_in_prefix
+    }
+
     pub(crate) fn integration_updates_available(&self) -> bool {
         self.integration_recommendations
             .iter()
@@ -1575,6 +1612,7 @@ impl AppState {
             cjk_ime_agent_filter_configured: false,
             cjk_ime_agents: Vec::new(),
             cjk_ime_cursor_shape: 2, // steady_block
+            switch_ascii_input_source_in_prefix: false,
             kitty_graphics_enabled: false,
             default_shell: String::new(),
             shell_mode: crate::config::ShellModeConfig::Auto,