vibe code the initial impl

main/detector.h

@@ -0,0 +1,31 @@
+#pragma once
+// Pure state machine: no ESP-IDF dependencies, can be compiled and tested on a PC.
+#include <stdbool.h>
+#include <stdint.h>
+
+typedef enum { DET_IDLE = 0, DET_TRIGGERED, DET_COOLDOWN } det_state_t;
+
+typedef struct {
+    uint32_t win_n;         // window length in frames (clamped to 1..32)
+    uint32_t win_m;         // matches required (clamped to 1..win_n)
+    uint32_t cooldown_ms;
+} detector_cfg_t;
+
+typedef struct {
+    det_state_t state;
+    uint32_t hist;          // bit 0 = newest frame, 1 = matched
+    uint32_t cooldown_start_ms;
+    uint32_t triggers;
+} detector_t;
+
+void detector_init(detector_t *d);
+void detector_reset(detector_t *d);     // back to IDLE with empty history
+
+// Loudness gate AND score >= threshold.
+bool detector_is_match(float rms, float score, float min_rms, float threshold);
+
+// Feed one frame. Returns true exactly once per trigger (IDLE -> TRIGGERED).
+// TRIGGERED lasts one frame, then COOLDOWN until cooldown_ms elapsed, then IDLE
+// with a cleared history (the buzzer's tail cannot re-trigger).
+bool detector_update(detector_t *d, bool match, uint32_t now_ms, const detector_cfg_t *cfg);
+const char *detector_state_name(det_state_t s);