feat(player): standardize independent playback; reset slot key memory on replay

ss_player/ss_internal_player.cpp

@@ -383,6 +383,11 @@ bool SsInternalPlayer::isPlaying() const {
 }
 
 void SsInternalPlayer::play(float p_start_frame) {
+    // play() always heads out (rewinds to a start frame); "resume" is pause()'s
+    // toggle, not play(). So a fresh play must clear each slot's "last started
+    // key" memory, otherwise a re-played animation would debounce an already-
+    // fired independent effect/instance as the same key and never re-fire it.
+    _reset_slots_playback_state();
     if (p_start_frame >= 0.0f) {
         ss_runtime_play_with_start_frame(runtime_ctx, p_start_frame);
     } else {
@@ -1432,6 +1437,19 @@ void SsInternalPlayer::_setup_effect_slots() {
     }
 }
 
+void SsInternalPlayer::_reset_slots_playback_state() {
+    for (uint32_t i = 0; i < _effect_slots.size(); i++) {
+        if (_effect_slots[i].effect_slot) ss_effect_slot_reset(_effect_slots[i].effect_slot);
+    }
+    for (uint32_t i = 0; i < _instance_children.size(); i++) {
+        InstanceChildState& st = _instance_children[i];
+        if (st.instance_slot) ss_instance_slot_reset(st.instance_slot);
+        // Recurse so a re-play also restarts independent effects/instances
+        // nested inside instance children (their slots live on the child).
+        if (st.player) st.player->_reset_slots_playback_state();
+    }
+}
+
 void SsInternalPlayer::_update_instance_children(float parent_frame_no, float delta_seconds, bool parent_looped) {
     if (!_currentAnimationData) {
         // No animation selected on the parent: keep all children hidden.

ss_player/ss_internal_player.h

@@ -624,6 +624,14 @@ class SsInternalPlayer {
     void _clear_instance_children();
     void _setup_effect_slots();
     void _clear_effect_slots();
+
+    // Reset every effect/instance slot's "last started key" memory (and recurse
+    // into instance children) so an explicit head-out re-fires independent
+    // effects/instances from scratch instead of debouncing the first key as the
+    // same one the slot last started. Called from `play()`. The reset itself
+    // lives in the runtime (`ss_effect_slot_reset` / `ss_instance_slot_reset`);
+    // the host only iterates the slots it owns.
+    void _reset_slots_playback_state();
     // Per-tick instance child driver. Runs in the sim phase (called from
     // `update`), before `_drawAnimation`. Per slot, queries
     // `ss_runtime_get_active_event_instance` (returns SS6 default semantics