feat(npc): push scene changes to voice gateway

On each scene change (where it already signals /hints/puzzle_start), the
npc_engine now also POSTs the active SCENE_* to the voice gateway
/game/step?scene=… (best-effort, esp_http_client, Bearer token). The
phone NPCs then disguise THIS scene's hint automatically during a game.
Gateway URL/token hardcoded in main.c like the hints URL (-> NVS later).

idf_zacus/components/npc_engine/CMakeLists.txt

@@ -22,6 +22,7 @@ idf_component_register(
     REQUIRES
         media_manager
         hints_client
+        esp_http_client
         esp_timer
         esp_system
         nvs_flash

idf_zacus/components/npc_engine/include/npc_engine.h

@@ -184,6 +184,12 @@ const npc_state_t *npc_engine_state(void);
 // Thin wrapper kept here to give callers a single npc_engine_* surface.
 esp_err_t npc_engine_set_group_profile(const char *profile);
 
+// Point the engine at the voice gateway (tools/zacus-gateway). On each scene
+// change the engine POSTs the active SCENE_* to {base_url}/game/step?scene=… so
+// the phone NPCs disguise that scene's hint. Best-effort; pass NULL/"" to
+// disable. `token` is sent as a Bearer header (gateway require_token).
+void npc_engine_set_gateway(const char *base_url, const char *token);
+
 // Write the active puzzle id (e.g. "SCENE_LA_DETECTOR") into `out`,
 // truncated to `cap` bytes (NUL-terminated). Falls back to "SCENE_NPC"
 // when no scene is active or the engine is not initialised so callers

idf_zacus/components/npc_engine/npc_engine.c

@@ -20,6 +20,7 @@
 #include <string.h>
 
 #include "esp_err.h"
+#include "esp_http_client.h"
 #include "esp_log.h"
 
 #include "media_manager.h"
@@ -27,6 +28,46 @@
 
 static const char *TAG = "npc_engine";
 
+// Voice gateway (tools/zacus-gateway) — we push the active SCENE_* to it at each
+// scene change so the phone NPCs disguise THIS scene's hint. Best-effort, set by
+// npc_engine_set_gateway(); empty = disabled (no-op, e.g. CI / dry runs).
+static char s_gw_url[128]   = {0};
+static char s_gw_token[80]  = {0};
+
+void npc_engine_set_gateway(const char *base_url, const char *token) {
+    if (base_url) snprintf(s_gw_url, sizeof(s_gw_url), "%s", base_url);
+    if (token)    snprintf(s_gw_token, sizeof(s_gw_token), "%s", token);
+}
+
+// Fire a one-shot POST {gateway}/game/step?scene=<scene>. Short timeout,
+// best-effort: the puzzle progresses fine without it, it only keeps the phone
+// NPCs' hints in sync with the current scene. Never propagates failure.
+static void notify_gateway_scene(const char *scene) {
+    if (!s_gw_url[0] || !scene || !scene[0]) return;
+    char url[256];
+    snprintf(url, sizeof(url), "%s/game/step?scene=%s", s_gw_url, scene);
+    esp_http_client_config_t cfg = {
+        .url = url,
+        .method = HTTP_METHOD_POST,
+        .timeout_ms = 2000,
+    };
+    esp_http_client_handle_t cli = esp_http_client_init(&cfg);
+    if (!cli) return;
+    if (s_gw_token[0]) {
+        char auth[112];
+        snprintf(auth, sizeof(auth), "Bearer %s", s_gw_token);
+        esp_http_client_set_header(cli, "Authorization", auth);
+    }
+    esp_err_t err = esp_http_client_perform(cli);
+    if (err != ESP_OK) {
+        ESP_LOGW(TAG, "gateway /game/step notify failed: %s", esp_err_to_name(err));
+    } else {
+        ESP_LOGI(TAG, "gateway scene -> %s (HTTP %d)", scene,
+                 esp_http_client_get_status_code(cli));
+    }
+    esp_http_client_cleanup(cli);
+}
+
 // ─── Core: scene/trigger/mood lookup tables (verbatim Arduino) ──────────────
 
 static const char *const kSceneIds[] = {
@@ -372,6 +413,8 @@ esp_err_t npc_engine_set_step(uint8_t step_id, uint32_t expected_duration_ms) {
                      (unsigned) prev_scene, (unsigned) step_id);
         }
         (void) hints_client_puzzle_start(puzzle_id);
+        // Keep the voice gateway in sync so the phone NPCs hint on THIS scene.
+        notify_gateway_scene(puzzle_id);
     }
     return ESP_OK;
 }

idf_zacus/main/main.c

@@ -63,6 +63,12 @@
 // this to NVS so the field operator can repoint the firmware without a flash.
 #define ZACUS_HINTS_BASE_URL  "http://192.168.0.150:8302"
 
+// Voice gateway (tools/zacus-gateway) — the engine POSTs each scene change to
+// {URL}/game/step?scene=SCENE_* so the phone NPCs disguise that scene's hint.
+// Hardcoded for now like the URLs above — moves to NVS in the same follow-up.
+#define ZACUS_GATEWAY_BASE_URL  "http://192.168.0.175:8401"
+#define ZACUS_GATEWAY_TOKEN     "testtoken"
+
 // Slice 7: voice-bridge WebSocket on the MacStudio (Tailscale address).
 // Hardcoded here for the same reason as ZACUS_HINTS_BASE_URL — moves to
 // NVS in a follow-up slice. The bridge endpoint is documented in
@@ -530,6 +536,9 @@ void app_main(void) {
                 ESP_LOGE(TAG, "npc_engine_init failed: %s",
                          esp_err_to_name(npc_err));
             }
+            // Push each scene change to the voice gateway so the phone NPCs
+            // disguise the CURRENT scene's hint (best-effort, see main.c URL).
+            npc_engine_set_gateway(ZACUS_GATEWAY_BASE_URL, ZACUS_GATEWAY_TOKEN);
 
             // Slice 5: bring up the hints HTTP client (so npc_engine can
             // route hint requests through the real backend) and the voice

plip_voice/main/audio.c

@@ -599,19 +599,14 @@ int audio_capture_wav(uint8_t *out, size_t out_max, int max_ms, int silence_ms)
     const int max_frames     = (max_ms     / 20);
     const int silence_frames = (silence_ms / 20);
 
-    /* VAD thresholds (raw S16). Tuned for the SLIC handset mic at +24 dB PGA:
-     * speech peaks ~5 % FS / RMS ~1-2 %, noise floor ~0.6 %. Onset must sit
-     * between (catch quiet speech), silence ABOVE the noise floor (so the turn
-     * ends when the caller stops instead of running to max_ms). */
-    /* Measured on the SLIC handset (DC-blocked): speech body sits ~1 % FS RMS
-     * with peaks ~18 %, noise floor ~0.3 %. The previous silence threshold
-     * (1.2 %) was ABOVE the speech body, so the recorder classified the
-     * caller's own voice as silence and cut the turn after ~0.6 s → empty STT.
-     * Onset must clear noise (3-frame sustained confirm also guards it); silence
-     * must sit between the noise floor and the speech body so the turn ends only
-     * on a real pause. */
-    const int32_t  vad_onset_rms_sq   = 450 * 450;   /* ~1.4% FS² — speech onset above noise */
-    const int32_t  vad_silence_rms_sq = 200 * 200;   /* ~0.6% FS² — below speech body, above noise floor */
+    /* Calibrated to the QUIET handset voice (DC-blocked: body 0.16-0.8 % FS RMS,
+     * loud syllables ~2-4 %, noise floor ~0.3 %). The old onset (1.4 %) NEVER
+     * triggered → "no sustained voice"; the old silence (0.6 %) sat ABOVE the
+     * body → cut mid-sentence. Now: onset catches a real syllable just above the
+     * floor (3-frame confirm guards clicks); silence sits just above the floor so
+     * the turn ends only on a true pause, holding the whole sentence. */
+    const int32_t  vad_onset_rms_sq   = 230 * 230;   /* ~0.70% FS² — quiet-voice onset */
+    const int32_t  vad_silence_rms_sq = 110 * 110;   /* ~0.34% FS² — just above noise floor */
 
     int  silent_frames = 0;
     int  total_frames  = 0;

plip_voice/main/conversation.c

@@ -47,7 +47,9 @@
 #define CAPTURE_MAX_IRAM    (128 * 1024)
 #define CAPTURE_MAX_MS_PSRAM  8000
 #define CAPTURE_MAX_MS_IRAM   4000
-#define CAPTURE_SILENCE_MS     600   /* end-of-speech VAD: shorter = snappier reply (was 800) */
+#define CAPTURE_SILENCE_MS     900   /* end-of-speech: needs to ride through brief
+                                      * mid-sentence pauses so a whole phrase is
+                                      * captured (quiet handset voice). 900 ms. */
 #define REPLY_POLL_MS          200   /* interval for checking hook during playback */
 #define REPLY_PLAYBACK_EXTRA_MS 500  /* safety margin added to computed WAV duration */
 #define BETWEEN_TURNS_MS       300   /* short pause between capture rounds */
@@ -124,6 +126,10 @@ static void enter_incoming_greet(void)
 {
     s_incoming_armed = false;
     phone_ring_stop();
+    slic_ring_stop();   /* belt-and-suspenders: kill the physical bell directly in
+                         * case phone.c's s_ringing flag desynced from slic.c's
+                         * (otherwise phone_ring_stop early-returns and the bell
+                         * keeps ringing through the answered call). */
     tones_stop();
     dialer_reset();
     s_offhook = true;