test: add test for double command processing bug

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

test_double_process.c

@@ -0,0 +1,77 @@
+// TODO: Remove this test after debugging the double status line issue
+// test_double_process.c
+#include "engine.h"
+#include <stdio.h>
+#include <assert.h>
+
+void test_command_processed_only_once(void) {
+    printf("Test: Command processed only once...\n");
+    
+    Engine engine;
+    memset(&engine, 0, sizeof(engine));
+    engine.sample_rate = 48000;
+    engine.control_channel = 0;
+    engine.quantize_mode = QUANTIZE_OFF;
+    engine.quantize_threshold = 0;
+    engine.queued_triggers = NULL;
+    
+    // Initialize command queue
+    command_queue_init(&engine.command_queue);
+    
+    // Initialize clips
+    for (int i = 0; i < MAX_CLIPS; i++) {
+        engine.clips[i].state = CLIP_EMPTY;
+        engine.clips[i].buffer = NULL;
+        engine.clips[i].buffer_size = 0;
+        engine.clips[i].write_position = 0;
+        engine.clips[i].read_position = 0;
+    }
+    
+    // Submit a trigger command
+    engine_trigger_clip(&engine, 0);
+    
+    // Check queue state
+    CommandQueue *q = &engine.command_queue;
+    unsigned int write = atomic_load(&q->write_index);
+    unsigned int read = atomic_load(&q->read_index);
+    printf("  Queue before process: write=%u, read=%u, pending=%u\n", 
+           write, read, write - read);
+    assert(write - read == 1);  // One command pending
+    
+    // Process once
+    engine_process_commands(&engine);
+    printf("  After first process: state=%d (expected %d=CLIP_RECORDING)\n",
+           engine.clips[0].state, CLIP_RECORDING);
+    assert(engine.clips[0].state == CLIP_RECORDING);
+    
+    // Check queue state after first process
+    write = atomic_load(&q->write_index);
+    read = atomic_load(&q->read_index);
+    printf("  Queue after first process: write=%u, read=%u, pending=%u\n", 
+           write, read, write - read);
+    assert(write - read == 0);  // No commands pending
+    
+    // Process again (simulating audio thread calling it)
+    engine_process_commands(&engine);
+    printf("  After second process: state=%d (expected %d=CLIP_RECORDING)\n",
+           engine.clips[0].state, CLIP_RECORDING);
+    
+    // If state changed, the command was processed twice
+    if (engine.clips[0].state != CLIP_RECORDING) {
+        printf("  BUG: State changed to %d on second process!\n", engine.clips[0].state);
+    } else {
+        printf("  OK: State unchanged after second process\n");
+    }
+    
+    // Cleanup
+    for (int i = 0; i < MAX_CLIPS; i++) {
+        free(engine.clips[i].buffer);
+    }
+    
+    printf("PASSED\n");
+}
+
+int main(void) {
+    test_command_processed_only_once();
+    return 0;
+}