clay-borg/games/ground/examples/regulation.rs

//! Does H1 do nothing, or does it do nothing **to a seat that already
//! manages its Stress**? (CB-WP-0039)
//!
//! [`CB-EV-0030`] measured ground-game's H1 with a panel that was
//! greedy-family throughout, and found DARVO never arms. But
//! `GreedyPolicy` ranks `Action::Ground if gated => 100`: the moment the
//! stress gate bites it grounds, Stress plateaus at 3, and the arm at 5
//! is unreachable **by construction**.
//!
//! H1 was written for the seat that does *not* do that. So this varies
//! **exactly one preference** — GROUND demoted below ATTACK — and holds
//! every other ranking identical to greedy's.
//!
//! [`CB-EV-0030`]: ../../../evidence/CB-EV-0030-h1-measured.md

use cb_game_runtime::{ScenarioGame, Setup};
use cb_kernel::PlayerId;
use games_ground::bot::{play, Choice, GreedyPolicy, Policy};
use games_ground::{Action, GroundCommand, GroundState, ScoringMode, Variant};

/// Greedy, with GROUND demoted below ATTACK. Nothing else differs.
///
/// **The copy is deliberate.** `GreedyPolicy::rank` is private, and the
/// point is to change one line of it while holding the rest identical —
/// calling into it would make that impossible to demonstrate.
struct Reactive;

impl Policy for Reactive {
    fn name(&self) -> &'static str {
        "reactive"
    }
    fn choose(
        &mut self,
        state: &GroundState,
        seat: PlayerId,
        legal: &[GroundCommand],
        _may_pass: bool,
    ) -> Choice {
        let gated = state
            .players
            .get(&seat)
            .is_some_and(|p| p.stress >= 4 && !p.freedom_gate_lifted);
        // ONE ARM OVERRIDDEN, THE REST DELEGATED.
        //
        // The first version re-typed greedy's ranking and changed one
        // line of the copy. It differed in five places, and the review
        // found it: `SpendFreedom` ranked 95 unconditionally instead of
        // greedy's `95 if gated else 0`, so this seat spent its Freedom
        // token in round one of every game — a second change to the very
        // mechanism under study. Delegating makes "exactly one preference
        // differs" structurally true instead of a claim in a comment.
        let rank = |c: &GroundCommand| -> i32 {
            match c {
                GroundCommand::SelectAction {
                    action: Action::Ground,
                    ..
                } if gated => 5,
                other => GreedyPolicy::rank(state, seat, other),
            }
        };
        let mut best = 0;
        for (i, c) in legal.iter().enumerate() {
            if rank(c) > rank(&legal[best]) {
                best = i;
            }
        }
        Choice::Command(best)
    }
}

/// `Scenarios.csv`: "All players start at Stress 2." Named rather than
/// inlined so the peak metric cannot silently disagree with setup.
const START_STRESS: u8 = 2;

struct Cell {
    games: u32,
    won: u32,
    atk: u32,
    darvo: u32,
    peak_stress: u8,
}

fn sweep(mode: ScoringMode, variant: Variant, players: u8, reactive: bool) -> Cell {
    let mut c = Cell {
        games: 0,
        won: 0,
        atk: 0,
        darvo: 0,
        peak_stress: 0,
    };
    for seed in 0..200u64 {
        let Ok(mut st) = GroundState::setup(
            &Setup {
                players,
                preset: format!("standard-{players}p"),
                patch: Default::default(),
            },
            seed,
        ) else {
            continue;
        };
        st.mode = mode;
        st.variant = variant;
        let mut ps: Vec<Box<dyn Policy>> = (0..players)
            .map(|_| {
                if reactive {
                    Box::new(Reactive) as Box<dyn Policy>
                } else {
                    Box::new(GreedyPolicy) as Box<dyn Policy>
                }
            })
            .collect();
        // A refused game is not a lost game (CB-EV-0030 §3).
        let g = match play(st, &mut ps) {
            Ok(g) => g,
            Err(e) => {
                eprintln!("  !! {players}p seed {seed}: {e:?}");
                continue;
            }
        };
        c.games += 1;
        if g.state.outcome.as_ref().is_some_and(|o| o.group_success) {
            c.won += 1;
        }
        for (_, cmd) in &g.steps {
            if let GroundCommand::SelectAction {
                action: Action::Attack,
                ..
            } = cmd
            {
                c.atk += 1;
            }
        }
        // Peak Stress **held**, not peak Stress *assigned*.
        //
        // The first version took a maximum over `StressSet` PAYLOADS.
        // Starting Stress is 2 and is written by `setup`, never by an
        // event, so a table that sat at 2 all game reported **1**, and a
        // table with no `StressSet` at all would report 0. CB-EV-0031 §2
        // built its headline claim on that number. Wrong subject: the
        // metric answered "highest value ever assigned", the prose said
        // "highest Stress reached".
        let mut held: std::collections::BTreeMap<PlayerId, u8> =
            g.state.players.keys().map(|s| (*s, START_STRESS)).collect();
        c.peak_stress = c.peak_stress.max(START_STRESS);
        for e in &g.events {
            if matches!(e, games_ground::GroundEvent::DarvoTriggered { .. }) {
                c.darvo += 1;
            }
            if let games_ground::GroundEvent::StressSet { player, stress } = e {
                held.insert(*player, *stress);
                c.peak_stress = c.peak_stress.max(*stress);
            }
        }
        let _ = held;
    }
    c
}

fn main() {
    println!("CB-WP-0039 — does H1 reach a seat that does not regulate?\n");
    println!("`reactive` is greedy with ONE preference changed: GROUND is");
    println!("demoted below ATTACK, so the seat never grounds to shed Stress.");
    println!("SHARED GROUND; `won` is group success; 200 games per cell.\n");

    for (vlabel, variant) in [
        ("BASELINE ground-darvo-r0", Variant::Baseline),
        ("H1 h1-problem-stress", Variant::H1ProblemStress),
    ] {
        println!("{vlabel}");
        println!("            greedy (regulates)          reactive (does not)");
        println!("seats   games won  atk darvo peak    games won  atk darvo peak");
        for players in [2u8, 3, 4, 6] {
            let g = sweep(ScoringMode::SharedGround, variant, players, false);
            let r = sweep(ScoringMode::SharedGround, variant, players, true);
            println!(
                "  {players}p    {:>4} {:>4} {:>4} {:>5} {:>4}    {:>4} {:>4} {:>4} {:>5} {:>4}",
                g.games,
                g.won,
                g.atk,
                g.darvo,
                g.peak_stress,
                r.games,
                r.won,
                r.atk,
                r.darvo,
                r.peak_stress
            );
        }
        println!();
    }
}