diff --git a/common_libs/tests/audit_virtual_guns.nim b/common_libs/tests/audit_virtual_guns.nim
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+## AUDIT TOOL (new file, read-only w.r.t. shipped source).
+##
+## Measures, over the committed fixture set:
+##   1. speed usage      — does each gun emit 4 DIFFERENT predictions for the 4
+##                         PowerBins, or does it ignore bulletSpeed?
+##   2. lead / accuracy  — bmPoint miss distance (arrival-time aim error) and the
+##                         bmPath "virtual" rate, so the optimism ratio is explicit.
+##   3. pairwise agreement of predictions (redundancy).
+##   4. conditional point hit rate by distance / speed / wall / reversal.
+##   5. feedback-integrity counters (waveStarved / traceMisses / trained).
+##
+## Usage:
+##   nim c -r --path:common_libs common_libs/tests/audit_virtual_guns.nim
+
+import std/[os, math, strformat, tables, algorithm, strutils, json, random]
+import gun_harness/offline_range
+import gun_harness/gun_interface
+import gun_harness/virtual_bullets as vb
+import guns/head_on
+import guns/linear
+import guns/tsetlin
+import guns/circular
+import guns/guess_factor
+import guns/pattern_matcher
+import guns/wall_bounce
+import guns/accel_predictor
+import guns/stop_shot
+import guns/displacement
+import guns/averaged_lead
+import guns/decay_gf
+import guns/knn_gun
+import guns/tm_selector
+
+const
+  NGun* = 14
+  GunNames*: array[NGun, string] = ["HeadOn","Linear","Tsetlin","Circular",
+    "GuessFactor","Pattern","WallBounce","Accel","StopShot","Displace","AvgLead",
+    "DecayGF","KNN","TMSelect"]
+  NBins = len(vb.PowerBins)
+
+type
+  Box[G] = ref object
+    g: G
+
+  Drivers* = object
+    d*: seq[GunDriver]
+    headOn*:   Box[HeadOnGun]
+    linear*:   Box[LinearGun]
+    tsetlin*:  Box[TsetlinGun]
+    circular*: Box[CircularGun]
+    gf*:       Box[GFGun]
+    pattern*:  Box[PatternMatcherGun]
+    wall*:     Box[WallBounceGun]
+    accel*:    Box[AccelGun]
+    stop*:     Box[StopShotGun]
+    disp*:     Box[DisplacementGun]
+    avg*:      Box[AveragedLeadGun]
+    decay*:    Box[DecayGFGun]
+    knn*:      Box[KNNGun]
+    tmsel*:    Box[TmSelectorGun]
+
+proc mk[G](name: string, g: Box[G]): GunDriver =
+  result.name = name
+  result.predictCb = proc(s: WorldState, sp: float): GunPrediction = g.g.predict(s, sp)
+  result.resultCb  = proc(e: FeedbackEvent) = g.g.onResult(e)
+  when compiles(g.g.isWarmedUp()):
+    result.readyCb = proc(): bool = g.g.isWarmedUp()
+  else:
+    result.readyCb = nil
+
+proc newBox[G](v: G): Box[G] =
+  new(result); result.g = v
+
+proc initDrivers*(seed = 1): Drivers =
+  result.headOn   = newBox(HeadOnGun())
+  result.linear   = newBox(LinearGun())
+  result.tsetlin  = newBox(initTsetlinGun())
+  result.circular = newBox(CircularGun())
+  result.gf       = newBox(initGFGun())
+  result.pattern  = newBox(PatternMatcherGun())
+  result.wall     = newBox(initWallBounceGun())
+  result.accel    = newBox(initAccelGun())
+  result.stop     = newBox(initStopShotGun())
+  result.disp     = newBox(initDisplacementGun())
+  result.avg      = newBox(initAveragedLeadGun())
+  result.decay    = newBox(initDecayGFGun())
+  result.knn      = newBox(initKNNGun())
+  result.tmsel    = newBox(initTmSelectorGun())
+  if seed >= 0: randomize(seed)
+  result.d = @[
+    mk("HeadOn", result.headOn), mk("Linear", result.linear),
+    mk("Tsetlin", result.tsetlin), mk("Circular", result.circular),
+    mk("GuessFactor", result.gf), mk("Pattern", result.pattern),
+    mk("WallBounce", result.wall), mk("Accel", result.accel),
+    mk("StopShot", result.stop), mk("Displace", result.disp),
+    mk("AvgLead", result.avg), mk("DecayGF", result.decay),
+    mk("KNN", result.knn), mk("TMSelect", result.tmsel),
+  ]
+
+# ── accumulators ──────────────────────────────────────────────────────────────
+
+type
+  BinAcc = object
+    count*, hits*: int
+    sumMiss*: float
+    within20*, within50*: int
+    sumPairDist*: float
+
+  ContextAcc = object
+    count*, hits*: int
+
+  GunAcc = object
+    bins: array[NBins, BinAcc]
+    # point-metric results (arrival-time aim accuracy)
+    ptCount*, ptHits*: int
+    ptSumMiss*: float
+    # prediction-diversity
+    identicalTicks*, predTicks*: int
+    sumSpread*: float            ## mean over ticks of max pairwise pred distance
+    # conditional point hit rate (pooled bins), marginal buckets
+    dist*: array[4, ContextAcc]
+    speed*: array[4, ContextAcc]
+    wall*: array[2, ContextAcc]
+    rev*: array[2, ContextAcc]
+    # virtual-path rate
+    vpCount*, vpHits*: int
+
+  Audit* = object
+    guns: array[NGun, GunAcc]
+    pairCount: array[NGun, array[NGun, int]]
+    pairWithin20: array[NGun, array[NGun, int]]
+    pairWithin50: array[NGun, array[NGun, int]]
+    pairSumDist: array[NGun, array[NGun, float]]
+    ticks*: int
+    fixtures*: int
+
+proc ctxDist(s: WorldState): int =
+  let d = hypot(s.enemyX - s.selfX, s.enemyY - s.selfY)
+  if d < 200.0: 0 elif d < 400.0: 1 elif d < 600.0: 2 else: 3
+
+proc ctxSpeed(s: WorldState): int =
+  let sp = abs(s.enemySpeed)
+  if sp < 1.0: 0 elif sp < 4.0: 1 elif sp < 7.5: 2 else: 3
+
+proc ctxWall(s: WorldState): int =
+  let m = min(min(s.enemyX, s.arenaWidth - s.enemyX),
+              min(s.enemyY, s.arenaHeight - s.enemyY))
+  if m < 60.0: 1 else: 0
+
+proc feedPredictions(a: var Audit, gi: int, preds: array[NBins, GunPrediction]) =
+  ## Speed usage: are the 4 bin predictions distinct?
+  var maxD = 0.0
+  for i in 0..<NBins:
+    for j in i+1..<NBins:
+      let d = hypot(preds[i].x - preds[j].x, preds[i].y - preds[j].y)
+      if d > maxD: maxD = d
+  inc a.guns[gi].predTicks
+  a.guns[gi].sumSpread += maxD
+  if maxD < 0.01: inc a.guns[gi].identicalTicks
+
+proc feedPairs(a: var Audit, preds: array[NGun, array[NBins, GunPrediction]]) =
+  for i in 0..<NGun:
+    for j in i+1..<NGun:
+      for b in 0..<NBins:
+        let d = hypot(preds[i][b].x - preds[j][b].x, preds[i][b].y - preds[j][b].y)
+        inc a.pairCount[i][j]
+        a.pairSumDist[i][j] += d
+        if d < 20.0: inc a.pairWithin20[i][j]
+        if d < 50.0: inc a.pairWithin50[i][j]
+
+proc auditReplay*(fx: Fixture, drivers: Drivers, metric: BulletMetric,
+                  a: ref Audit, capPreds: bool) =
+  ## One replay pass. `metric` selects the virtual scoring model. Captures
+  ## bmPoint FeedbackEvents into the point/context accumulators; bmPath into the
+  ## virtual-rate accumulators; prediction diversity/pairwise always.
+  let n = drivers.d.len
+  let tid = fx.enemyId
+  a.ticks += fx.states.len
+  a.fixtures += 1
+  var tracker = vb.initTracker(n, metric)
+  var byTick = initTable[int, int]()
+  for si in 0..<fx.states.len: byTick[fx.states[si].tick] = si
+  var prevSpeed = 0.0
+
+  for si in 0..<fx.states.len:
+    let state = fx.states[si]
+    var allPreds: array[NGun, array[NBins, GunPrediction]]
+    for gi in 0..<n:
+      var preds: array[NBins, GunPrediction]
+      for i in 0..<NBins:
+        preds[i] = drivers.d[gi].predictCb(state, bulletSpeed(vb.PowerBins[i]))
+      allPreds[gi] = preds
+      if capPreds: feedPredictions(a[], gi, preds)
+      let ready = if drivers.d[gi].readyCb == nil: true else: drivers.d[gi].readyCb()
+      if ready:
+        tracker.spawnBullets(gi, preds, state, tid)
+    if capPreds: feedPairs(a[], allPreds)
+
+    let act = state
+    var enemyPositions: Table[int, tuple[x, y: float, lastSeenTick: int, alive: bool]]
+    for e in act.enemies:
+      enemyPositions[e.id] = (x: e.x, y: e.y, lastSeenTick: e.lastSeenTick, alive: true)
+
+    prevSpeed = state.enemySpeed
+
+    tracker.tickBullets(state, enemyPositions,
+      proc(gunId: GunId, binIdx: int, e: FeedbackEvent) =
+        if gunId < 0 or gunId >= NGun: return
+        drivers.d[gunId].resultCb(e)   # feed the owning gun its own feedback
+        if metric == bmPoint:
+          let ga = addr a.guns[gunId]
+          inc ga.ptCount
+          ga.ptSumMiss += e.missDistance
+          if e.hit: inc ga.ptHits
+          # context buckets (from fire-time state)
+          let fsIdx = byTick.getOrDefault(e.fireTick, si)
+          let fs = fx.states[fsIdx]
+          inc ga.dist[ctxDist(fs)].count
+          inc ga.speed[ctxSpeed(fs)].count
+          inc ga.wall[ctxWall(fs)].count
+          let r = if fsIdx > 0:
+                    let ps = fx.states[fsIdx-1].enemySpeed
+                    ps != 0.0 and fs.enemySpeed != 0.0 and (ps > 0.0) != (fs.enemySpeed > 0.0)
+                  else: false
+          inc ga.rev[ord(r)].count
+          if e.hit:
+            inc ga.dist[ctxDist(fs)].hits
+            inc ga.speed[ctxSpeed(fs)].hits
+            inc ga.wall[ctxWall(fs)].hits
+            inc ga.rev[ord(r)].hits
+        else:
+          inc a.guns[gunId].vpCount
+          if e.hit: inc a.guns[gunId].vpHits
+        discard binIdx)
+
+proc addGunAcc(dst: var GunAcc, src: GunAcc) =
+  for b in 0..<NBins:
+    dst.bins[b].count += src.bins[b].count
+    dst.bins[b].hits += src.bins[b].hits
+    dst.bins[b].sumMiss += src.bins[b].sumMiss
+    dst.bins[b].within20 += src.bins[b].within20
+    dst.bins[b].within50 += src.bins[b].within50
+    dst.bins[b].sumPairDist += src.bins[b].sumPairDist
+  dst.ptCount += src.ptCount; dst.ptHits += src.ptHits; dst.ptSumMiss += src.ptSumMiss
+  dst.identicalTicks += src.identicalTicks; dst.predTicks += src.predTicks
+  dst.sumSpread += src.sumSpread
+  for k in 0..<4:
+    dst.dist[k].count += src.dist[k].count; dst.dist[k].hits += src.dist[k].hits
+    dst.speed[k].count += src.speed[k].count; dst.speed[k].hits += src.speed[k].hits
+  for k in 0..<2:
+    dst.wall[k].count += src.wall[k].count; dst.wall[k].hits += src.wall[k].hits
+    dst.rev[k].count += src.rev[k].count; dst.rev[k].hits += src.rev[k].hits
+  dst.vpCount += src.vpCount; dst.vpHits += src.vpHits
+
+proc rate(h, n: int): float = (if n == 0: 0.0 else: h.float / n.float * 100.0)
+
+# ── feedback-integrity counters ───────────────────────────────────────────────
+type
+  CounterAcc* = object
+    gfPush*, gfStarve*, decPush*, decStarve*, knnPush*, knnStarve*: int
+    tmTrained*, tmMisses*, tmPredict*, tmCorr*: int
+    selTrain*, selMiss*, selObs*, selPredict*: int
+
+var ctrPath: CounterAcc
+
+proc collectCounters(d: Drivers, c: var CounterAcc) =
+  c.gfPush     += d.gf.g.wavePushes;     c.gfStarve  += d.gf.g.waveStarved
+  c.decPush    += d.decay.g.wavePushes;  c.decStarve += d.decay.g.waveStarved
+  c.knnPush    += d.knn.g.wavePushes;    c.knnStarve += d.knn.g.waveStarved
+  c.tmTrained  += d.tsetlin.g.trainedShots
+  c.tmMisses   += d.tsetlin.g.traceMisses
+  c.tmPredict  += d.tsetlin.g.predictCalls
+  c.tmCorr     += d.tsetlin.g.correctionsNonzero
+  c.selTrain   += d.tmsel.g.trainCalls
+  c.selMiss    += d.tmsel.g.traceMisses
+  c.selObs     += d.tmsel.g.totalObs
+  c.selPredict += d.tmsel.g.predictCalls
+
+# ── main ──────────────────────────────────────────────────────────────────────
+
+const fixturesDir = currentSourcePath().parentDir.parentDir.parentDir / "tools" / "fixtures"
+
+var
+  accPoint: Audit
+  accPath: Audit
+
+proc runFile(path: string) =
+  var fx = loadFixture(path)
+  if fx.states.len < 50: return
+  let MaxTicks = (if existsEnv("AUDIT_MAX_TICKS"): parseInt(getEnv("AUDIT_MAX_TICKS"))
+                  else: 4000)
+  if fx.states.len > MaxTicks:
+    fx.states.setLen(MaxTicks)
+    if fx.lastSeen.len > MaxTicks: fx.lastSeen.setLen(MaxTicks)
+  let dPoint = initDrivers(seed = 1)
+  var a = new(Audit)
+  auditReplay(fx, dPoint, bmPoint, a, capPreds = false)
+  for gi in 0..<NGun: accPoint.guns[gi].addGunAcc(a.guns[gi])
+
+  let dPath = initDrivers(seed = 1)
+  var b = new(Audit)
+  auditReplay(fx, dPath, bmPath, b, capPreds = true)
+  collectCounters(dPath, ctrPath)
+  accPath.ticks += b.ticks
+  accPath.fixtures += b.fixtures
+  for gi in 0..<NGun:
+    accPath.guns[gi].addGunAcc(b.guns[gi])
+  for i in 0..<NGun:
+    for j in 0..<NGun:
+      accPath.pairCount[i][j] += b.pairCount[i][j]
+      accPath.pairWithin20[i][j] += b.pairWithin20[i][j]
+      accPath.pairWithin50[i][j] += b.pairWithin50[i][j]
+      accPath.pairSumDist[i][j] += b.pairSumDist[i][j]
+  echo fmt"# {path} ticks={fx.states.len}"
+
+proc printCounters() =
+  echo ""
+  echo "=================== FEEDBACK INTEGRITY (bmPath pass) ==================="
+  echo fmt"GF      pushes={ctrPath.gfPush:<8} starved={ctrPath.gfStarve}"
+  echo fmt"DecayGF pushes={ctrPath.decPush:<8} starved={ctrPath.decStarve}"
+  echo fmt"KNN     pushes={ctrPath.knnPush:<8} starved={ctrPath.knnStarve}"
+  echo fmt"Tsetlin trained={ctrPath.tmTrained:<8} misses={ctrPath.tmMisses:<8} predicts={ctrPath.tmPredict:<8} corrNonzero={ctrPath.tmCorr}"
+  echo fmt"TMSelect trained={ctrPath.selTrain:<8} misses={ctrPath.selMiss:<8} obs={ctrPath.selObs:<8} predicts={ctrPath.selPredict}"
+
+proc main() =
+  var files: seq[string]
+  for i in 1..paramCount(): files.add paramStr(i)
+  if files.len == 0:
+    for f in walkFiles(fixturesDir / "tr_drussgt_*.jsonl"): files.add f
+    for f in walkFiles(fixturesDir / "drussgt_*.jsonl"): files.add f
+  files.sort()
+  for f in files:
+    runFile(f)
+
+  printCounters()
+
+  echo ""
+  echo "=================== PER-GUN SUMMARY (all fixtures) ==================="
+  echo fmt"fixtures={accPath.fixtures} ticks={accPath.ticks}"
+  echo "gun          vpath%   point%  ratio  ident%  spread  leadPx  ptMiss"
+  for gi in 0..<NGun:
+    let g = addr accPath.guns[gi]
+    let vp = rate(g.vpHits, g.vpCount)
+    let pp = rate(accPoint.guns[gi].ptHits, accPoint.guns[gi].ptCount)
+    let ratio = if pp > 0.0: vp / pp else: 0.0
+    let ident = rate(g.identicalTicks, g.predTicks)
+    let spread = if g.predTicks > 0: g.sumSpread / g.predTicks.float else: 0.0
+    let ptMiss = if accPoint.guns[gi].ptCount > 0:
+                   accPoint.guns[gi].ptSumMiss / accPoint.guns[gi].ptCount.float else: 0.0
+    echo fmt"{GunNames[gi]:<12} {vp:6.1f}  {pp:6.1f}  {ratio:5.2f}  {ident:6.1f}  {spread:6.1f}  {ptMiss:6.1f}"
+  echo "(vpath% = shipped bmPath virtual rate; point% = bmPoint arrival-accuracy rate;"
+  echo " ident% = ticks whose 4 power-bin predictions are identical; spread = mean max"
+  echo " pairwise bin distance px; ptMiss = mean bmPoint miss distance px)"
+
+  echo ""
+  echo "=================== TOP REDUNDANT PAIRS (pred within 20px / 50px) ==================="
+  type Pair = tuple[pct20, pct50, meanD: float, i, j: int]
+  var pairs: seq[Pair]
+  for i in 0..<NGun:
+    for j in i+1..<NGun:
+      let n = accPath.pairCount[i][j]
+      if n == 0: continue
+      pairs.add (pct20: rate(accPath.pairWithin20[i][j], n),
+                 pct50: rate(accPath.pairWithin50[i][j], n),
+                 meanD: accPath.pairSumDist[i][j] / n.float, i: i, j: j)
+  pairs.sort(proc(x, y: Pair): int = cmp(y.pct20, x.pct20))
+  for p in pairs[0..<min(18, pairs.len)]:
+    echo fmt"{GunNames[p.i]:<11} ~ {GunNames[p.j]:<11}  <20px {p.pct20:5.1f}%  <50px {p.pct50:5.1f}%  mean {p.meanD:6.1f}px"
+
+  echo ""
+  echo "===== FULL PAIR MATRIX (% ticks 4-bin preds within 20px) ====="
+  var hdr = "            "
+  for j in 0..<NGun: hdr.add fmt"{GunNames[j][0..<min(6,GunNames[j].len)]:>8}"
+  echo hdr
+  for i in 0..<NGun:
+    var row = fmt"{GunNames[i]:<12}"
+    for j in 0..<NGun:
+      if i == j: row.add "      --"
+      elif j < i: row.add "        "
+      else:
+        let n = accPath.pairCount[i][j]
+        row.add fmt"{rate(accPath.pairWithin20[i][j], n):8.1f}"
+    echo row
+
+  echo ""
+  echo "=================== CONDITIONAL bmPoint HIT RATE ==================="
+  echo "gun          d<200    200-400   400-600   600+    v<1      v1-4    v4-7.5   v>=7.5  wall  open  rev   fwd"
+  for gi in 0..<NGun:
+    let g = addr accPoint.guns[gi]
+    var line = fmt"{GunNames[gi]:<12}"
+    for k in 0..<4: line.add fmt"{rate(g.dist[k].hits, g.dist[k].count):6.1f}  "
+    for k in 0..<4: line.add fmt"{rate(g.speed[k].hits, g.speed[k].count):6.1f}  "
+    line.add fmt"{rate(g.wall[1].hits, g.wall[1].count):6.1f} "
+    line.add fmt"{rate(g.wall[0].hits, g.wall[0].count):6.1f} "
+    line.add fmt"{rate(g.rev[1].hits, g.rev[1].count):6.1f} "
+    line.add fmt"{rate(g.rev[0].hits, g.rev[0].count):6.1f}"
+    echo line
+
+  echo ""
+  echo "=================== SAMPLE SIZES (bmPoint per-gun) ==================="
+  for gi in 0..<NGun:
+    let g = addr accPoint.guns[gi]
+    echo fmt"{GunNames[gi]:<12} pointN={g.ptCount:<7} vpathN={accPath.guns[gi].vpCount:<7} predTicks={accPath.guns[gi].predTicks}"
+
+when isMainModule:
+  main()