feat(experimental): add reveal_hidden_cursor_for_cjk_ime opt-in for CJK IME tracking

When the focused pane requests ?25l (cursor hidden) but paints its own
cursor — common in TUIs like Claude Code, pi, and codex — macOS native
input methods stop tracking the candidate-window position. CJK users
(Chinese / Japanese / Korean) cannot see candidate windows follow as
they type. Setting [experimental] reveal_hidden_cursor_for_cjk_ime = true
exposes the focused pane's cursor anchor to the outer terminal regardless
of the pane's hidden-cursor request, restoring IME tracking for CJK input.

[experimental] cjk_ime_agents is an optional allow-list. When empty,
the reveal applies to any focused pane. When non-empty (e.g.
["claude", "codex"]), the reveal only applies if the focused pane's
detected agent matches one of the listed names. This lets users enable
the workaround only for AI-agent TUIs that paint their own cursor,
leaving plain shells and other programs untouched. Accepted names: pi,
claude, codex, gemini, cursor, cline, opencode, copilot, kimi, kiro,
droid, amp, grok, hermes. Unknown names are ignored.

When the pane reports no cursor position (cursor_state returns None for
some TUIs), the anchor falls back to the pane's top-left so a stable
IME hint is always available.

[experimental] cjk_ime_cursor_shape (default "steady_block") controls
the DECSCUSR shape rendered for the revealed cursor; six variants are
accepted: block, steady_block, underline, steady_underline, bar,
steady_bar.

Trade-off when enabled: a hardware cursor will be visible in the outer
terminal for apps that hide the cursor without painting a replacement.
Default false preserves the behavior set in 2c95071. Pair the reveal
with cjk_ime_agents to scope it to specific TUIs.

Manually verified on macOS 26.5 aarch64 with system Pinyin IME against
Claude Code: candidate window tracks cursor with flag enabled, returns
to anchored-at-start behavior with flag disabled.

refs #149

1 files changed, 11 insertions, 0 deletions

diff --git a/src/app/state.rs b/src/app/state.rs
index 7ee79c4a..1566fdeb 100644
--- a/src/app/state.rs
+++ b/src/app/state.rs
@@ -965,6 +965,14 @@ pub struct AppState {
     pub confirm_close: bool,
     pub prompt_new_tab_name: bool,
     pub show_agent_labels_on_pane_borders: bool,
+    /// Expose the focused pane's cursor anchor to the outer terminal even when
+    /// the pane requested `?25l`. See `[experimental] reveal_hidden_cursor_for_cjk_ime`.
+    pub reveal_hidden_cursor_for_cjk_ime: bool,
+    /// Restrict cursor reveal to focused panes whose detected agent matches
+    /// one of these. Empty means apply to any focused pane.
+    pub cjk_ime_agents: Vec<crate::detect::Agent>,
+    /// DECSCUSR shape parameter (1–6) for the IME anchor cursor.
+    pub cjk_ime_cursor_shape: u8,
     pub kitty_graphics_enabled: bool,
     pub default_shell: String,
     pub pane_scrollback_limit_bytes: usize,
@@ -1224,6 +1232,9 @@ impl AppState {
             confirm_close: true,
             prompt_new_tab_name: true,
             show_agent_labels_on_pane_borders: false,
+            reveal_hidden_cursor_for_cjk_ime: false,
+            cjk_ime_agents: Vec::new(),
+            cjk_ime_cursor_shape: 2, // steady_block
             kitty_graphics_enabled: false,
             default_shell: String::new(),
             pane_scrollback_limit_bytes: crate::config::DEFAULT_SCROLLBACK_LIMIT_BYTES,