feat(SNNBot): encode perpendicular velocity for unambiguous lead

relVelDir ±5° shared 80% of bits despite needing opposite lead.
Now encodes v_perp = speed×sin(relVelDir) directly with signed
thermometer coding — positive and negative crossing velocities
have zero bit overlap. Also adds v_parallel for approach/recede.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SNNBot_garage/src/SNNBot.nim

@@ -321,40 +321,46 @@ method onBulletHit*(bot: SNNBot, e: BulletHitBotEvent) =
 
 # ── Reservoir helpers ─────────────────────────────────────────────────────────
 
-proc toBinaryInput(bearing: float, velDir: float, velSpeed: float, distance: float, hasVel: bool): BitVec80 =
+proc toBinaryInput(relVelDir: float, velSpeed: float, distance: float, hasVel: bool): BitVec80 =
   ## 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 36-43: 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
+  ## Bits  0-15: v_perp signed thermometer — velSpeed*sin(relVelDir) in [-8,+8].
+  ##             Positive (target moves right): bits 0-7; negative (left): bits 8-15.
+  ##             +3 sets bits 0,1,2; -3 sets bits 8,9,10. Zero overlap between signs.
+  ## Bits 16-31: v_parallel signed thermometer — velSpeed*cos(relVelDir) in [-8,+8].
+  ##             Positive = approaching (less lead needed), negative = receding.
+  ## Bits 32-39: distance thermometer, 8 bands of ~125px in [0,1000].
+  ## Bits 40-47: total speed thermometer, 8 bands of 1 unit/tick.
+  ## Bits 48-79: unused.
   result = [0'u64, 0'u64]
 
-  if hasVel:
-    # Relative velocity direction: how the target crosses our line of fire
-    var relVelDir = (velDir - bearing)
-    while relVelDir >= 180.0: relVelDir -= 360.0
-    while relVelDir < -180.0: relVelDir += 360.0
-    let vNorm = (relVelDir + 180.0) / 10.0  # 0..36
-    let vCenter = int(vNorm) mod 36
-    for offset in -2 .. 2:
-      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))
+  template setThermo(baseIdx: int, value: float) =
+    ## Signed thermometer: positive → bits baseIdx..baseIdx+7, negative → bits baseIdx+8..baseIdx+15.
+    let mag = min(int(abs(value)), 8)
+    if value >= 0.0:
+      for b in 0 ..< mag:
+        let idx = baseIdx + b
+        result[idx div 64] = result[idx div 64] or (1'u64 shl (idx mod 64))
+    else:
+      for b in 0 ..< mag:
+        let idx = baseIdx + 8 + b
+        result[idx div 64] = result[idx div 64] or (1'u64 shl (idx mod 64))
 
-    # Speed thermometer: bits 36-43; set bits 36..(36+speedInt-1)
-    # speedInt=0 → no bits; speedInt=8 → all 8 bits set
+  if hasVel:
+    let vPerp = velSpeed * sin(degToRad(relVelDir))   # lateral speed, range [-8,+8]
+    let vPar  = velSpeed * cos(degToRad(relVelDir))   # approach speed, range [-8,+8]
+    setThermo(0,  vPerp)
+    setThermo(16, vPar)
+
+    # Total speed thermometer: bits 40-47
     let speedInt = clamp(int(velSpeed + 0.5), 0, 8)
     for b in 0 ..< speedInt:
-      let idx = 36 + b
+      let idx = 40 + b
       result[idx div 64] = result[idx div 64] or (1'u64 shl (idx mod 64))
 
-  # Distance thermometer: bits 44-51, 8 bands of ~125px over [0,1000]
-  # All bits up to the current band set (inclusive)
+  # Distance thermometer: bits 32-39, 8 bands of ~125px over [0,1000]
   let band = clamp(int(distance / 125.0), 0, 7)
   for b in 0 .. band:
-    let idx = 44 + b
+    let idx = 32 + b
     result[idx div 64] = result[idx div 64] or (1'u64 shl (idx mod 64))
 
 # ── Main loop ─────────────────────────────────────────────────────────────────
@@ -381,7 +387,10 @@ method run*(bot: SNNBot) =
       let absBearing = bot.enemyBearing
       bot.lastRelBearing = normalizeRelativeAngle(absBearing - gunDir)
       when USE_RESERVOIR:
-        let binInput = toBinaryInput(absBearing, bot.velDirDeg, bot.velSpeed, bot.enemyDist, bot.hasLastPos)
+        var relVelDir = bot.velDirDeg - absBearing
+        while relVelDir >= 180.0: relVelDir -= 360.0
+        while relVelDir < -180.0: relVelDir += 360.0
+        let binInput = toBinaryInput(relVelDir, bot.velSpeed, bot.enemyDist, bot.hasLastPos)
         let aimOffset = bot.res.forward(binInput)   # lead correction offset or -999.0 sentinel
         bot.lastBinInput     = binInput
         bot.lastDecideGunDir = gunDir