From cc3c2649c287719baafb8c005454a32a6cad95a4 Mon Sep 17 00:00:00 2001
From: Davide Cappellini <signorsasso@gmail.com>
Date: Wed, 16 Sep 2026 23:10:04 +0200
Subject: [PATCH] feat(SNNBot): thermometer speed encoding for precise lead
 discrimination
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

3-bit speed encoding couldn't distinguish speed 3 from speed 5 —
9° of lead error baked into the input. Thermometer coding with 8 bits
gives 1-bit Hamming distance between adjacent speeds. MAX_K back to 128.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 SNNBot_garage/src/SNNBot.nim    | 22 ++++++++++++----------
 SNNBot_garage/src/reservoir.nim |  2 +-
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/SNNBot_garage/src/SNNBot.nim b/SNNBot_garage/src/SNNBot.nim
index 306d51f..99adee5 100644
--- a/SNNBot_garage/src/SNNBot.nim
+++ b/SNNBot_garage/src/SNNBot.nim
@@ -1,6 +1,6 @@
 # SNNBot — SNN core + aiming loop prototype (issue #152).
 # 80-input population-coded → 12 LIF hidden → polar-coded (sin/cos) output decoded via atan2.
-# Inputs: relVelDir [0-35], speed [36-38], distance thermometer [39-46]. Raw bearing removed (irrelevant to lead).
+# Inputs: relVelDir [0-35], speed thermometer [36-43], distance thermometer [44-51]. Raw bearing removed (irrelevant to lead).
 # No movement, no firing. SuperSpike three-factor rule on all weights (issue #158).
 # Binary reservoir alternative toggled via USE_RESERVOIR const (issue #159).
 #
@@ -325,9 +325,10 @@ proc toBinaryInput(bearing: float, velDir: float, velSpeed: float, distance: flo
   ## Physics-based encoding for lead generalization (issue #152).
   ## Raw bearing removed — irrelevant to lead offset.
   ## Bits  0-35: relVelDir = (velDir - bearing) normalized to [-180,180), 36 bins × 10°, 5 active (center ± 2 neighbors).
-  ## Bits 36-38: speed level (3 bits, center ± 1 neighbor).
-  ## Bits 39-46: distance thermometer, 8 bands of ~125px in [0,1000].
-  ## Bits 47-79: unused (sparse is fine for popcount similarity).
+  ## Bits 36-43: speed thermometer (8 bits): speedInt bits set from bit 36 upward, 0-8 active.
+  ##             Adjacent speeds differ by 1 bit (Hamming-1), giving smooth generalization.
+  ## Bits 44-51: distance thermometer, 8 bands of ~125px in [0,1000].
+  ## Bits 52-79: unused.
   ## ponytail: physics-based; revert to absolute bearing if convergence regresses
   result = [0'u64, 0'u64]
 
@@ -342,17 +343,18 @@ proc toBinaryInput(bearing: float, velDir: float, velSpeed: float, distance: flo
       let idx = (vCenter + offset + 36) mod 36  # bits 0-35
       result[idx div 64] = result[idx div 64] or (1'u64 shl (idx mod 64))
 
-    # Speed: bits 36-38, center ± 1 neighbor clamped to [0,2]
-    let sCenter = clamp(int(velSpeed), 0, 2)
-    for offset in -1 .. 1:
-      let idx = 36 + clamp(sCenter + offset, 0, 2)
+    # Speed thermometer: bits 36-43; set bits 36..(36+speedInt-1)
+    # speedInt=0 → no bits; speedInt=8 → all 8 bits set
+    let speedInt = clamp(int(velSpeed + 0.5), 0, 8)
+    for b in 0 ..< speedInt:
+      let idx = 36 + b
       result[idx div 64] = result[idx div 64] or (1'u64 shl (idx mod 64))
 
-  # Distance thermometer: bits 39-46, 8 bands of ~125px over [0,1000]
+  # Distance thermometer: bits 44-51, 8 bands of ~125px over [0,1000]
   # All bits up to the current band set (inclusive)
   let band = clamp(int(distance / 125.0), 0, 7)
   for b in 0 .. band:
-    let idx = 39 + b
+    let idx = 44 + b
     result[idx div 64] = result[idx div 64] or (1'u64 shl (idx mod 64))
 
 # ── Main loop ─────────────────────────────────────────────────────────────────
diff --git a/SNNBot_garage/src/reservoir.nim b/SNNBot_garage/src/reservoir.nim
index eb7c305..926439e 100644
--- a/SNNBot_garage/src/reservoir.nim
+++ b/SNNBot_garage/src/reservoir.nim
@@ -5,7 +5,7 @@ import std/[bitops, math]
 const
   INPUT_BITS* = 80
   WORDS_IN*   = 2       # 80 bits → 2 × uint64 (128 bits, only 80 used)
-  MAX_K*      = 64
+  MAX_K*      = 128
   MIN_SIM*    = 3
 
 type