Shift_L and Shift_R cannot be distinguished in ascii_composer - shared shift_key_pressed_ state

[xiaoqing2265]

Bug Description

When configuring Shift_R: noop and Shift_L: commit_code, pressing Right Shift + ' to input paired quotes still triggers input method switching. The expected behavior is that only Left Shift should toggle ascii_mode.

Environment

• OS: macOS 15+ (Sequoia)
• Rime frontend: Squirrel
• librime version: 1.13.0

Configuration

# default.custom.yaml
patch:
  ascii_composer/switch_key/Shift_L: commit_code
  ascii_composer/switch_key/Shift_R: noop

##Root Cause Analysis
In src/rime/gear/ascii_composer.cc, there is a single shift_key_pressed_ boolean variable that doesn't distinguish between Left and Right Shift:

// ascii_composer.h
bool shift_key_pressed_ = false;  // Shared state, doesn't track L/R

// ascii_composer.cc - key down
if (is_shift)
    shift_key_pressed_ = true;  // Doesn't record which Shift was pressed

// ascii_composer.cc - key up
if (is_shift && shift_key_pressed_ && now < toggle_expired_) {
    ToggleAsciiModeWithKey(ch);  // Uses actual keycode (XK_Shift_L or XK_Shift_R)
}

The code correctly uses XK_Shift_L / XK_Shift_R keycodes to distinguish Left/Right in ToggleAsciiModeWithKey(), but the shift_key_pressed_ state variable conflates both.

Proposed Fix

Split shift_key_pressed_ into shift_l_pressed_ and shift_r_pressed_:

// ascii_composer.h
bool shift_l_pressed_ = false;
bool shift_r_pressed_ = false;

// ascii_composer.cc - key down
if (ch == XK_Shift_L)
    shift_l_pressed_ = true;
else if (ch == XK_Shift_R)
    shift_r_pressed_ = true;

// ascii_composer.cc - key up
if (key_event.release()) {
    if ((ch == XK_Shift_L && shift_l_pressed_) ||
        (ch == XK_Shift_R && shift_r_pressed_)) {
        if (now < toggle_expired_) {
            ToggleAsciiModeWithKey(ch);
        }
    }
    if (ch == XK_Shift_L) shift_l_pressed_ = false;
    if (ch == XK_Shift_R) shift_r_pressed_ = false;
}

Steps to Reproduce

1.Configure Shift_R: noop and Shift_L: commit_code
2.Deploy Rime
3.In. any app, switch to Chinese input mode
4.Press Right Shift + ' to input paired quote "
5.Observe that input method switches to English (unexpected)

Expected Behavior

Only Left Shift should trigger the mode switch. Right Shift + punctuation should not change the input mode.