diff --git a/tools/_dbg_contact.py b/tools/_dbg_contact.py
new file mode 100644
index 00000000..f0405518
--- /dev/null
+++ b/tools/_dbg_contact.py
@@ -0,0 +1,81 @@
+import sys, json
+sys.path.insert(0, '.')
+from tooling.rl_self_play.harness_client import HarnessClient, HarnessConfig
+from tooling.rl_self_play.encoders import encode_legal_actions
+from tooling.rl_self_play.record_expert import _DropStats, _resolve
+
+
+def adv(c, slot):
+    for a in c.suggest(slot=slot):
+        v = c.view(slot=slot)
+        _, i2a = encode_legal_actions(v)
+        idx = _resolve(a, v, i2a, _DropStats())
+        if idx is None:
+            continue
+        r = i2a[idx]
+        try:
+            if r.get('type') == 'end_turn':
+                c.end_turn(slot=slot)
+            else:
+                c.act(r, slot=slot)
+        except Exception:
+            break
+    try:
+        c.end_turn(slot=slot)
+    except Exception:
+        pass
+    c.drain_notifications()
+
+
+def ents(v, slot, key):
+    return [x for x in v.get(key, []) if int(x.get('owner', -1)) == slot]
+
+
+def pos(x):
+    p = x.get('position', [-99, -99])
+    return (float(p[0]), float(p[1]))
+
+
+def wrapdist(a, b, w=40, h=24):
+    dx = abs(a[0] - b[0]); dx = min(dx, w - dx)
+    dy = abs(a[1] - b[1]); dy = min(dy, h - dy)
+    return (dx * dx + dy * dy) ** 0.5
+
+
+def min_interplayer_dist(v):
+    p0 = [pos(x) for x in ents(v, 0, 'units')] + [pos(x) for x in ents(v, 0, 'cities')]
+    p1 = [pos(x) for x in ents(v, 1, 'units')] + [pos(x) for x in ents(v, 1, 'cities')]
+    if not p0 or not p1:
+        return -1
+    return min(wrapdist(a, b) for a in p0 for b in p1)
+
+
+for seed in (1, 6):
+    c = HarnessClient(HarnessConfig(seed=seed, players=2, player_slots=(0, 1),
+                      map_size='duel', map_type='pangaea',
+                      victory_mode='domination', timeout_sec=110))
+    v = c.view(1)
+    cap0 = [pos(x) for x in ents(v, 0, 'cities')]
+    cap1 = [pos(x) for x in ents(v, 1, 'cities')]
+    print('seed%d t0: P0cap=%s P1cap=%s capdist=%.1f' % (
+        seed, cap0, cap1, wrapdist(cap0[0], cap1[0]) if cap0 and cap1 else -1))
+    prev0 = prev1 = 0
+    combat_seen = False
+    mindist_ever = 999
+    for rnd in range(58):
+        v = c.view(1)
+        n0 = len(ents(v, 0, 'units')); n1 = len(ents(v, 1, 'units'))
+        # mil drop relative to prior peak observed = combat loss signal
+        if rnd > 0 and (n0 < prev0 or n1 < prev1):
+            combat_seen = True
+        prev0, prev1 = max(prev0, n0), max(prev1, n1)
+        d = min_interplayer_dist(v)
+        if d >= 0:
+            mindist_ever = min(mindist_ever, d)
+        if rnd % 15 == 0:
+            print('  t%d: P0u=%d P1u=%d mindist=%.1f' % (
+                int(v.get('turn', 0)), n0, n1, d))
+        adv(c, 0); adv(c, 1)
+    print('  seed%d SUMMARY: combat_seen(mil_drop)=%s  min_interplayer_dist_ever=%.1f' % (
+        seed, combat_seen, mindist_ever))
+    c.shutdown()