diff --git a/meshtastic/deviceonly.proto b/meshtastic/deviceonly.proto
index ec28b59d..7e025c14 100644
--- a/meshtastic/deviceonly.proto
+++ b/meshtastic/deviceonly.proto
@@ -187,8 +187,11 @@ message NodeInfoLite {
 
   /*
    * Q4-encoded SNR: dB × 4, sint32 zigzag. Matches RouteDiscovery convention.
-   * Encode: snr_q4 = (int32_t)(snr * 4.0f). Decode: snr = snr_q4 / 4.0f.
+   * Encode: snr_q4 = (int32_t)lroundf(snr * 4.0f). Decode: snr = snr_q4 / 4.0f.
    * float snr is always zeroed on disk; this field carries all persisted SNR.
+   * A stored 0 does not by itself mean "unknown" here - see NODEINFO_BITFIELD_HAS_SNR in
+   * src/mesh/NodeDB.h for the presence bit that disambiguates a genuine 0 dB reading from
+   * "never measured".
    */
   sint32 snr_q4 = 19;
 }
diff --git a/meshtastic/mesh.proto b/meshtastic/mesh.proto
index b09a15b0..008cc1f6 100644
--- a/meshtastic/mesh.proto
+++ b/meshtastic/mesh.proto
@@ -1848,8 +1848,11 @@ message MeshPacket {
 
   /*
    * rssi of received packet. Only sent to phone for dispay purposes.
+   * Explicit presence: rssi 0 is a legitimate reading on some radios (SX126x can report exactly
+   * 0 dBm; SX127x's formula can even go positive). has_rx_rssi disambiguates; a replayed packet
+   * built from history should leave this field absent rather than emitting 0.
    */
-  int32 rx_rssi = 12;
+  optional int32 rx_rssi = 12;
 
   /*
    * Describe if this message is delayed
@@ -1864,6 +1867,10 @@ message MeshPacket {
   /*
    * Hop limit with which the original packet started. Sent via LoRa using three bits in the unencrypted header.
    * When receiving a packet, the difference between hop_start and hop_limit gives how many hops it traveled.
+   * hop_start == 0 does not necessarily mean a direct (0-hop) neighbor: firmware prior to 2.3.0
+   * never populated this field, so a receiver can only trust hop_start == 0 as genuine once it has
+   * decoded the packet and confirmed the sender's bitfield is present (added in 2.5.0). Until then,
+   * or for a sender that never sets that bitfield, treat hop_start == 0 as unknown, not direct.
    */
   uint32 hop_start = 15;