Drop variant B, adopt Black-belt Exam defender, add one-sidedness metrics

- Remove variant B (Brown cap, +1 for higher beating lower) from rules,
  engine, bots and simulator; a higher belt beating a lower one gains 0.
- Final Exam: the defender fights as a Black belt (RULES.md v0.7). Ties to
  the defender and best-of-3 stay as simulator switches (`--exam`).
- Report stripe income per source as gains and losses.
- Add ten one-sidedness measures sampled at turn ends (lead gap, winner
  margin and lead share, halfway leader, last lead change, contention,
  rank swaps, leader Kumite losses, Exam challengers, winner pace).
- Plan: decisions D28-D33 and the detailed Phase 6.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/dojo/report.py

@@ -5,34 +5,43 @@ import dataclasses
 from collections.abc import Iterable
 from pathlib import Path
 
-from dojo.events import Source
 from dojo.metrics import GameMetrics, Spread, Summary
 
 
 def format_summary(summary: Summary) -> str:
-    income = summary.income_per_turn
     seats = ", ".join(f"{seat} {rate:.0%}" for seat, rate in enumerate(summary.win_rate_by_seat))
     bots = ", ".join(f"{bot} {rate:.0%}" for bot, rate in summary.win_rate_by_bot.items())
+    income = ", ".join(
+        f"{source} +{gain:.2f}/{loss:.2f}"
+        for source, (gain, loss) in summary.income_per_turn.items()
+    )
     lines = [
         f"== {summary.scenario}  ({summary.games} games, {summary.finished:.0%} finished)",
-        f"Rounds        {_spread(summary.rounds)}",
-        f"Minutes       {_spread(summary.minutes)}",
-        f"Kumite        {summary.kumite_per_round:.2f}/round; upsets {summary.upset_rate:.0%}, "
-        f"higher beats lower {summary.expected_rate:.0%}",
-        f"Longest chain {_spread(summary.max_chain)}  (Kumite in one turn, per game)",
-        f"Exam          {summary.exam_attempts_per_game:.2f} attempts/game, "
-        f"{summary.exam_success:.0%} passed",
-        f"Stuck on 14   {summary.turns_on_14_per_game:.2f} turns/game, "
-        f"longest streak {summary.longest_14_streak} turns",
-        f"Income/turn   square {income[Source.SQUARE]:+.2f} "
-        f"(home {summary.square_income_home_per_turn:+.2f}, "
-        f"away {summary.square_income_away_per_turn:+.2f}), "
-        f"card {income[Source.CARD]:+.2f}, kumite {income[Source.KUMITE]:+.2f}, "
-        f"exam {income[Source.EXAM]:+.2f}",
-        f"Lead changes  {_spread(summary.lead_changes)}",
-        f"Final spread  {_spread(summary.final_spread)}",
-        f"Wins by seat  {seats}",
-        f"Wins by bot   {bots}",
+        f"Rounds          {_spread(summary.rounds)}",
+        f"Minutes         {_spread(summary.minutes)}",
+        f"Kumite          {summary.kumite_per_round:.2f}/round; upsets {summary.upset_rate:.0%}, "
+        f"higher beats lower (no stripes change) {summary.expected_rate:.0%}",
+        f"Longest chain   {_spread(summary.max_chain)}  (Kumite in one turn, per game)",
+        f"Exam            {summary.exam_attempts_per_game:.2f} attempts/game, "
+        f"{summary.exam_success:.0%} passed, {summary.exam_challengers:.2f} challengers/game",
+        f"Income/turn     {income}",
+        f"Square income   home {summary.square_income_home_per_turn:+.2f}/turn, "
+        f"away {summary.square_income_away_per_turn:+.2f}/turn (net)",
+        f"Winner pace     {_spread(summary.winner_turns_to_brown)}  (own turns to reach Brown)",
+        f"Lead changes    {_spread(summary.lead_changes)}",
+        f"Last change     {_shares(summary.last_lead_change)}  (point of the game)",
+        f"Gap 1st-2nd     {_spread(summary.lead_gap)}  (per-game mean, stripes)",
+        f"Winner margin   {_spread(summary.winner_margin)}  (over best rival at the end)",
+        f"Winner led      {summary.winner_lead_share:.0%} of turns; halfway leader won "
+        f"{summary.halfway_leader_wins:.0%} of {summary.halfway_games} games",
+        f"Contention      {summary.contenders_at_end:.2f} rivals within one belt at the end; "
+        f"{summary.out_of_contention:.0%} of player-turns out (>2 belts behind)",
+        f"Worst player    {_shares(summary.worst_out_of_contention)}  (share of turns out)",
+        f"Rank swaps      {_spread(summary.rank_swaps)}",
+        f"Leader beaten   {summary.leader_kumite_losses:.2f} Kumite lost by the leader per game",
+        f"Final spread    {_spread(summary.final_spread)}",
+        f"Wins by seat    {seats}",
+        f"Wins by bot     {bots}",
     ]
     return "\n".join(lines)
 
@@ -51,3 +60,10 @@ def _spread(spread: Spread) -> str:
         f"mean {spread.mean:.1f}  p10 {spread.p10:.1f}  median {spread.median:.1f}  "
         f"p90 {spread.p90:.1f}"
     )
+
+
+def _shares(spread: Spread) -> str:
+    return (
+        f"mean {spread.mean:.0%}  p10 {spread.p10:.0%}  median {spread.median:.0%}  "
+        f"p90 {spread.p90:.0%}"
+    )