diff --git a/zephcore/ARCHITECTURE.md b/zephcore/ARCHITECTURE.md
index 3d40a53..3395486 100644
--- a/zephcore/ARCHITECTURE.md
+++ b/zephcore/ARCHITECTURE.md
@@ -687,7 +687,7 @@ DIO1 interrupt → Zephyr lora driver → async RX callback
     → k_event_post(MESH_EVENT_LORA_RX) → main thread wakes
       → Dispatcher::loop() → checkRecv() → drain ring buffer
         → tryParsePacket() → score + airtime calc
-          → flood: calcRxDelay() → queue inbound or process immediately
+          → flood: dedup + adaptive contention delay → queue for retransmit
           → direct: process immediately
             → Mesh::onRecvPacket() → decrypt → dispatch by type
               → BaseChatMesh::onPeerDataRecv() → onMessageRecv()
diff --git a/zephcore/adapters/radio/LoRaRadioBase.cpp b/zephcore/adapters/radio/LoRaRadioBase.cpp
index 760b68e..819d014 100644
--- a/zephcore/adapters/radio/LoRaRadioBase.cpp
+++ b/zephcore/adapters/radio/LoRaRadioBase.cpp
@@ -598,7 +598,11 @@ uint32_t LoRaRadioBase::getEstAirtimeFor(int len_bytes)
 	float t_sym = (float)(1 << sf) / (bw * 1000.0f);
 	float t_preamble = (preambleLengthForSF(sf) + 4.25f) * t_sym;
 
-	float de = (sf >= 11) ? 1.0f : 0.0f;
+	/* LDRO threshold must track the SX126x driver's should_enable_ldro()
+	 * exactly (symbol time > 16.38 ms) so this estimate's DE matches the
+	 * hardware's DE on every SF/BW pair.  The old `sf >= 11` was only
+	 * correct at BW 125 kHz and diverged on every other bandwidth. */
+	float de = (t_sym > 0.01638f) ? 1.0f : 0.0f;
 	float num = 8.0f * len_bytes - 4.0f * sf + 28.0f + 16.0f;
 	float den = 4.0f * (sf - 2.0f * de);
 	if (den < 1.0f) den = 4.0f;
diff --git a/zephcore/include/mesh/Dispatcher.h b/zephcore/include/mesh/Dispatcher.h
index 8f53aa4..f39fc86 100644
--- a/zephcore/include/mesh/Dispatcher.h
+++ b/zephcore/include/mesh/Dispatcher.h
@@ -84,7 +84,6 @@ protected:
 	virtual const char *getLogDateTime() { return ""; }
 	virtual uint8_t getDutyCyclePercent() const;
 	static bool isAdminPacket(const Packet *pkt);
-	virtual int calcRxDelay(float score, uint32_t air_time) const;
 	virtual uint32_t getCADFailRetryDelay() const;
 	virtual uint32_t getCADFailMaxDuration() const;
 	virtual int getInterferenceThreshold() const { return 0; }
diff --git a/zephcore/src/Dispatcher.cpp b/zephcore/src/Dispatcher.cpp
index 6172c1b..1ba2512 100644
--- a/zephcore/src/Dispatcher.cpp
+++ b/zephcore/src/Dispatcher.cpp
@@ -21,7 +21,6 @@ LOG_MODULE_REGISTER(zephcore_dispatcher, CONFIG_ZEPHCORE_LORA_LOG_LEVEL);
 
 namespace mesh {
 
-#define MAX_RX_DELAY_MILLIS         32000  /* upper bound for score-based RX delay */
 #define MIN_TX_BUDGET_AIRTIME_DIV   2      /* require at least 1/N MTU airtime as budget before TX */
 
 Dispatcher::Dispatcher(Radio &radio, MillisecondClock &ms, PacketManager &mgr)
@@ -105,22 +104,6 @@ bool Dispatcher::isAdminPacket(const Packet *pkt)
 	       t == PAYLOAD_TYPE_ANON_REQ || t == PAYLOAD_TYPE_CONTROL;
 }
 
-int Dispatcher::calcRxDelay(float score, uint32_t air_time) const
-{
-	/* LUT: 10^(0.85 - i*0.1) - 1, i=0..10; replaces powf() (~1.9KB saved) */
-	static const float lut[11] = {
-		6.0793f, 4.6236f, 3.4674f, 2.5489f, 1.8184f, 1.2389f,
-		0.7783f, 0.4125f, 0.1220f, -0.1089f, -0.2921f
-	};
-	if (score <= 0.0f) return (int)(lut[0] * (float)air_time);
-	if (score >= 1.0f) return (int)(lut[10] * (float)air_time);
-	float idx = score * 10.0f;
-	int i = (int)idx;
-	float frac = idx - (float)i;
-	float val = lut[i] + frac * (lut[i + 1] - lut[i]);
-	return (int)(val * (float)air_time);
-}
-
 uint32_t Dispatcher::getCADFailRetryDelay() const
 {
 	/* 100-200ms jittered retry: tighter than one SF8 flood airtime so we