From b0ad3b3d19dfed3ed7942f4fabc5dce55509477b Mon Sep 17 00:00:00 2001
From: Loic Coenen <loic@visua.com>
Date: Fri, 1 May 2026 23:28:33 +0000
Subject: [PATCH] fix: add undo support for transport state changes

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>
---
 engine.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
 engine.h |  3 ++-
 2 files changed, 71 insertions(+), 4 deletions(-)

diff --git a/engine.c b/engine.c
index fc17955..826f2db 100644
--- a/engine.c
+++ b/engine.c
@@ -441,17 +441,53 @@ void engine_process_commands(Engine *engine) {
                 engine_redo(engine);
                 break;
                 
-            case CMD_TRANSPORT_PLAY:
+            case CMD_TRANSPORT_PLAY: {
+                // Record undo action
+                UndoAction action;
+                action.type = ACTION_TRANSPORT_STATE_CHANGE;
+                action.index = 0;
+                action.value = (jack_nframes_t)engine->transport->state;
+                action.previous_clock_count = engine->transport->clock_count;
+                action.previous_beat_position = engine->transport->beat_position;
+                action.previous_bar_position = engine->transport->bar_position;
+                action.previous_sample_position = engine->transport->sample_position;
+                engine_push_undo_action(engine, &action);
+                
                 transport_play(engine->transport);
                 break;
+            }
+                
+            case CMD_TRANSPORT_PAUSE: {
+                // Record undo action
+                UndoAction action;
+                action.type = ACTION_TRANSPORT_STATE_CHANGE;
+                action.index = 0;
+                action.value = (jack_nframes_t)engine->transport->state;
+                action.previous_clock_count = engine->transport->clock_count;
+                action.previous_beat_position = engine->transport->beat_position;
+                action.previous_bar_position = engine->transport->bar_position;
+                action.previous_sample_position = engine->transport->sample_position;
+                engine_push_undo_action(engine, &action);
                 
-            case CMD_TRANSPORT_PAUSE:
                 transport_pause(engine->transport);
                 break;
+            }
+                
+            case CMD_TRANSPORT_STOP: {
+                // Record undo action
+                UndoAction action;
+                action.type = ACTION_TRANSPORT_STATE_CHANGE;
+                action.index = 0;
+                action.value = (jack_nframes_t)engine->transport->state;
+                action.previous_clock_count = engine->transport->clock_count;
+                action.previous_beat_position = engine->transport->beat_position;
+                action.previous_bar_position = engine->transport->bar_position;
+                action.previous_sample_position = engine->transport->sample_position;
+                engine_push_undo_action(engine, &action);
                 
-            case CMD_TRANSPORT_STOP:
                 transport_stop(engine->transport);
                 break;
+            }
                 
             case CMD_TRANSPORT_TOGGLE_PLAY:
                 transport_toggle_play(engine->transport);
@@ -571,6 +607,21 @@ void engine_undo(Engine *engine) {
             atomic_store(&engine->transport->sample_position_atomic, action->previous_sample_position);
             break;
         }
+            
+        case ACTION_TRANSPORT_STATE_CHANGE: {
+            TransportState prev_state = (TransportState)action->value;
+            engine->transport->state = prev_state;
+            engine->transport->clock_count = action->previous_clock_count;
+            engine->transport->beat_position = action->previous_beat_position;
+            engine->transport->bar_position = action->previous_bar_position;
+            engine->transport->sample_position = action->previous_sample_position;
+            atomic_store(&engine->transport->state_atomic, prev_state);
+            atomic_store(&engine->transport->clock_count_atomic, action->previous_clock_count);
+            atomic_store(&engine->transport->beat_position_atomic, action->previous_beat_position);
+            atomic_store(&engine->transport->bar_position_atomic, action->previous_bar_position);
+            atomic_store(&engine->transport->sample_position_atomic, action->previous_sample_position);
+            break;
+        }
     }
     
     history->undo_index--;
@@ -688,6 +739,21 @@ void engine_redo(Engine *engine) {
             atomic_store(&engine->transport->sample_position_atomic, 0);
             break;
         }
+            
+        case ACTION_TRANSPORT_STATE_CHANGE: {
+            TransportState prev_state = (TransportState)action->value;
+            engine->transport->state = prev_state;
+            engine->transport->clock_count = action->previous_clock_count;
+            engine->transport->beat_position = action->previous_beat_position;
+            engine->transport->bar_position = action->previous_bar_position;
+            engine->transport->sample_position = action->previous_sample_position;
+            atomic_store(&engine->transport->state_atomic, prev_state);
+            atomic_store(&engine->transport->clock_count_atomic, action->previous_clock_count);
+            atomic_store(&engine->transport->beat_position_atomic, action->previous_beat_position);
+            atomic_store(&engine->transport->bar_position_atomic, action->previous_bar_position);
+            atomic_store(&engine->transport->sample_position_atomic, action->previous_sample_position);
+            break;
+        }
     }
     
     history->undo_index++;
diff --git a/engine.h b/engine.h
index 88e3c88..288b90e 100644
--- a/engine.h
+++ b/engine.h
@@ -69,7 +69,8 @@ typedef enum {
     ACTION_RESET_CLIP,
     ACTION_SET_QUANTIZE_MODE,
     ACTION_SET_QUANTIZE_THRESHOLD,
-    ACTION_RESET_TRANSPORT
+    ACTION_RESET_TRANSPORT,
+    ACTION_TRANSPORT_STATE_CHANGE
 } ActionType;
 
 // Undo/Redo action record