Fix Cmd+Shift+V: add timing-based same-hand hold for mod-taps in get_chordal_hold

Agent-Logs-Url: https://github.com/timfee/qmk_userspace/sessions/682413db-c19e-483e-bdef-6b171183b6de

Co-authored-by: timfee <3246342+timfee@users.noreply.github.com>

users/timfee/timfee.c

@@ -26,15 +26,35 @@ const char chordal_hold_layout[MATRIX_ROWS][MATRIX_COLS] PROGMEM = {
 };
 
 // ── Chordal Hold per-key override ──
-// Layer-tap keys (ESC_L2, MIN_L1) must always resolve as hold when
-// another key is pressed so the layer activates — even for same-hand keys.
-// Mod-tap keys use the default layout-based logic (cross-hand = hold).
+// Layer-tap keys always resolve as hold so the layer activates for
+// same-hand keys.  Cross-hand mod-tap chords always resolve as hold.
+// Same-hand mod-tap chords use a timing heuristic: if the other key
+// arrives within 150 ms of the tap-hold key press it is a fast typing
+// roll (tap); otherwise the user is deliberately holding a modifier
+// for a shortcut like Cmd+V or Cmd+Shift+V (hold).
+#define CHORDAL_SAME_HAND_MS 150
+
 bool get_chordal_hold(uint16_t tap_hold_keycode, keyrecord_t *tap_hold_record,
                       uint16_t other_keycode, keyrecord_t *other_record) {
+    // Layer-tap: always hold (layers need same-hand access).
     if (IS_QK_LAYER_TAP(tap_hold_keycode)) {
         return true;
     }
-    return get_chordal_hold_default(tap_hold_record, other_record);
+
+    // Cross-hand: always hold (standard chordal behaviour).
+    if (get_chordal_hold_default(tap_hold_record, other_record)) {
+        return true;
+    }
+
+    // Same-hand mod-tap: timing decides tap vs hold.
+    if (IS_QK_MOD_TAP(tap_hold_keycode)) {
+        uint16_t elapsed =
+            other_record->event.time - tap_hold_record->event.time;
+        return elapsed >= CHORDAL_SAME_HAND_MS;
+    }
+
+    // Any other same-hand combo: tap.
+    return false;
 }
 
 // ── Combos (matching Vial config) ──