diff --git a/idf_zacus/components/npc_engine/CMakeLists.txt b/idf_zacus/components/npc_engine/CMakeLists.txt
index a0f5ccb..dc845ed 100644
--- a/idf_zacus/components/npc_engine/CMakeLists.txt
+++ b/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
diff --git a/idf_zacus/components/npc_engine/include/npc_engine.h b/idf_zacus/components/npc_engine/include/npc_engine.h
index e1b2c77..d320be3 100644
--- a/idf_zacus/components/npc_engine/include/npc_engine.h
+++ b/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
diff --git a/idf_zacus/components/npc_engine/npc_engine.c b/idf_zacus/components/npc_engine/npc_engine.c
index 9829689..2a4df1e 100644
--- a/idf_zacus/components/npc_engine/npc_engine.c
+++ b/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;
 }
diff --git a/idf_zacus/main/main.c b/idf_zacus/main/main.c
index 6f71c72..8967cfe 100644
--- a/idf_zacus/main/main.c
+++ b/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