1 files changed, 42 insertions, 3 deletions
diff --git a/tools/seq_compiler.cc b/tools/seq_compiler.cc
index 45cfc1a..7ac921f 100644
--- a/tools/seq_compiler.cc
+++ b/tools/seq_compiler.cc
@@ -467,13 +467,52 @@ int main(int argc, char* argv[]) {
                   << ": EFFECT found outside of SEQUENCE\n";
         return 1;
       }
-      std::string class_name, start, end, priority;
-      if (!(ss >> class_name >> start >> end >> priority)) {
+      std::string priority_mod, class_name, start, end;
+      if (!(ss >> priority_mod >> class_name >> start >> end)) {
         std::cerr << "Error line " << line_num
-                  << ": EFFECT requires <Class> <start> <end> <priority>\n";
+                  << ": EFFECT requires <+|=|-> <Class> <start> <end>\n";
         return 1;
       }
 
+      // Validate priority modifier
+      if (priority_mod != "+" && priority_mod != "=" && priority_mod != "-") {
+        std::cerr << "Error line " << line_num
+                  << ": Priority modifier must be '+', '=', or '-', got: " << priority_mod << "\n";
+        return 1;
+      }
+
+      // Calculate priority based on modifier and sequence state
+      static int current_priority = 0;
+      static bool first_in_sequence = true;
+      static const SequenceEntry* last_seq = nullptr;
+
+      // Reset priority tracking for new sequence
+      if (current_seq != last_seq) {
+        current_priority = 0;
+        first_in_sequence = true;
+        last_seq = current_seq;
+      }
+
+      // Handle first effect in sequence
+      if (first_in_sequence) {
+        if (priority_mod == "-") {
+          current_priority = -1;  // Background layer
+        } else {
+          current_priority = 0;   // Default start (+ or =)
+        }
+        first_in_sequence = false;
+      } else {
+        // Update priority based on modifier for subsequent effects
+        if (priority_mod == "+") {
+          current_priority++;
+        } else if (priority_mod == "-") {
+          current_priority--;
+        }
+        // '=' keeps current_priority unchanged
+      }
+
+      std::string priority = std::to_string(current_priority);
+
       // Convert beat notation to time
       std::string start_time = convert_to_time(start, bpm);
       std::string end_time = convert_to_time(end, bpm);