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

2 files changed, 34 insertions, 0 deletions

diff --git a/src/app/mod.rs b/src/app/mod.rs
index b87eec66..5cc40ecc 100644
--- a/src/app/mod.rs
+++ b/src/app/mod.rs
@@ -153,6 +153,21 @@ fn agent_panel_scope_from_config(
     }
 }
 
+/// Parse the configured agent name list into a deduplicated set of `Agent`
+/// values. Unknown agent names are silently dropped so a typo cannot disable
+/// other valid entries.
+fn parse_cjk_ime_agents(names: &[String]) -> Vec<crate::detect::Agent> {
+    let mut out = Vec::with_capacity(names.len());
+    for name in names {
+        if let Some(agent) = crate::detect::parse_agent_label(name) {
+            if !out.contains(&agent) {
+                out.push(agent);
+            }
+        }
+    }
+    out
+}
+
 /// Resolve the palette from config: base theme + optional custom overrides.
 fn resolve_palette(config: &crate::config::Config) -> state::Palette {
     resolve_palette_with_legacy_accent(config, true)
@@ -412,6 +427,9 @@ impl App {
             confirm_close: config.ui.confirm_close,
             prompt_new_tab_name: config.ui.prompt_new_tab_name,
             show_agent_labels_on_pane_borders: config.ui.show_agent_labels_on_pane_borders,
+            reveal_hidden_cursor_for_cjk_ime: config.experimental.reveal_hidden_cursor_for_cjk_ime,
+            cjk_ime_agents: parse_cjk_ime_agents(&config.experimental.cjk_ime_agents),
+            cjk_ime_cursor_shape: config.experimental.cjk_ime_cursor_shape.to_decscusr(),
             kitty_graphics_enabled: config.experimental.kitty_graphics,
             default_shell: config.terminal.default_shell.clone(),
             pane_scrollback_limit_bytes: config.advanced.scrollback_limit_bytes,
@@ -887,6 +905,11 @@ impl App {
             if was_kitty_graphics_enabled && !config.experimental.kitty_graphics {
                 let _ = crate::kitty_graphics::clear_all_host_graphics();
             }
+            self.state.reveal_hidden_cursor_for_cjk_ime =
+                config.experimental.reveal_hidden_cursor_for_cjk_ime;
+            self.state.cjk_ime_agents = parse_cjk_ime_agents(&config.experimental.cjk_ime_agents);
+            self.state.cjk_ime_cursor_shape =
+                config.experimental.cjk_ime_cursor_shape.to_decscusr();
         }
 
         if !invalid_section("advanced") {
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,