Enable acknowledged RX retune caches for RAK3401

docs/test-results/rak3401_radio2_sf5_bw500_p384_2026-10-23.md

@@ -93,9 +93,10 @@ time. An unplugged-USB, SWD-only sleep experiment would be a separate test.
 
 Source inspection found concrete speed candidates, without changing this
 baseline: RAK currently uses the default 2 MHz byte-at-a-time SPI path,
-although a buffered nRF52 HAL exists; the retune path also performs modem
-queries during setup and maximum-airtime calculation. Their individual costs
-were not measured by this capture. Faster switching and any receiver repair
+although a buffered nRF52 HAL exists; the retune path also queries the modem
+during setup and repeats the IQ workaround. Its custom airtime override already
+uses cached parameters and does not issue a second modem query. Their individual
+costs were not measured by this capture. Faster switching and any receiver repair
 need fresh source-bound RF validation before a qualification claim.
 
 ## Controller correction and restoration

test/test_profile_sx1262_iq_cache.py

@@ -21,7 +21,8 @@ class ProfileIqCacheTest(unittest.TestCase):
                          recipe.read_text(), re.MULTILINE):
                 opt_ins.append(recipe.relative_to(ROOT).as_posix())
         self.assertCountEqual(opt_ins, ["variants/sensecap_indicator-espnow/platformio.ini",
-                                       "variants/lilygo_tdeck/platformio.ini"])
+                                       "variants/lilygo_tdeck/platformio.ini",
+                                       "variants/rak3401/platformio.ini"])
 
     def compile_run(self, source):
         with tempfile.TemporaryDirectory() as folder:

variants/rak3401/platformio.ini

@@ -19,6 +19,10 @@ build_flags = ${nrf52_base.build_flags}
   -D OLED_AUTO_DETECT=1 ; shared WisBlock SSD1306 / SH1106 screen support
   -D RADIO_CLASS=CustomSX1262
   -D WRAPPER_CLASS=CustomSX1262Wrapper
+  ; Retain acknowledged LoRa/IQ state only across owned warm RX profile hops.
+  ; Sleep, TX/CAD, reset and failed commands still revoke these caches.
+  -D MC_SX1262_FAST_MODEM_CACHE=1
+  -D MC_SX1262_FAST_IQ_CACHE=1
   -D LORA_TX_POWER=22
   -D SX126X_CURRENT_LIMIT=140
   -D SX126X_RX_BOOSTED_GAIN=1