vyndr/tests/unit/projectionChallenger.test.js

/* proj-v1 — matchup read + orchestration. Champion untouched; never abstains. */
const pc = require('../../src/services/projectionChallenger');
const mr = require('../../src/services/projection/matchupRead');

// A sinker-heavy, high-whiff arsenal.
const SINKER_ARM = mr.classifyArsenal([
  { type: 'SI', usage_pct: 45, whiff_pct: 12, hard_hit_pct: 40 },
  { type: 'SL', usage_pct: 30, whiff_pct: 34, hard_hit_pct: 30 },
  { type: 'CH', usage_pct: 25, whiff_pct: 30, hard_hit_pct: 32 },
]);
// A fastball-heavy, low-whiff (pitch-to-contact) arsenal.
const FB_ARM = mr.classifyArsenal([
  { type: 'FF', usage_pct: 65, whiff_pct: 16, hard_hit_pct: 44 },
  { type: 'FC', usage_pct: 20, whiff_pct: 18, hard_hit_pct: 40 },
  { type: 'CU', usage_pct: 15, whiff_pct: 20, hard_hit_pct: 30 },
]);
// A fly-ball (high launch angle), hard-hit hitter; and a whiff-prone, flatter one.
const flyBat = { whiff_pct: 22, chase_pct: 28, hard_hit_pct: 46, avg_launch_angle: 20 };
const whiffBat = { whiff_pct: 34, chase_pct: 34, hard_hit_pct: 34, avg_launch_angle: 10 };

describe('arsenal classification', () => {
  it('buckets usage by pitch family + carries whiff/hard-hit tendency', () => {
    expect(SINKER_ARM.sinker_pct).toBeCloseTo(0.45, 2);
    expect(SINKER_ARM.breaking_pct).toBeCloseTo(0.30, 2);
    expect(SINKER_ARM.whiff_tendency).toBeGreaterThan(FB_ARM.whiff_tendency);
  });
  it('absent mix → null (no matchup contribution, honest)', () => {
    expect(mr.classifyArsenal(null)).toBeNull();
    expect(mr.classifyArsenal([])).toBeNull();
  });
});

describe('matchup direction (two-sided, coarse repertoire-vs-profile)', () => {
  it('a groundy sinker arm SUPPRESSES a fly-ball hitter\'s power (HR mult < 1)', () => {
    const m = mr.matchupMultiplier({ arsenal: SINKER_ARM, hitter: mr.hitterProfile(flyBat), statType: 'home_runs' });
    expect(m.multiplier).toBeLessThan(1);
    expect(m.components.some((c) => c.label === 'air_suppression')).toBe(true);
  });
  it('a high-whiff arsenal SUPPRESSES a whiff-prone hitter\'s hits (hits mult < 1)', () => {
    const m = mr.matchupMultiplier({ arsenal: SINKER_ARM, hitter: mr.hitterProfile(whiffBat), statType: 'hits' });
    expect(m.multiplier).toBeLessThan(1);
  });
  it('the SAME whiff pressure moves a STRIKEOUT prop the other way (mult > 1)', () => {
    const m = mr.matchupMultiplier({ arsenal: SINKER_ARM, hitter: mr.hitterProfile(whiffBat), statType: 'strikeouts' });
    expect(m.multiplier).toBeGreaterThan(1);
  });
  it('missing either side → neutral 1.0 (never fabricates a matchup)', () => {
    expect(mr.matchupMultiplier({ arsenal: null, hitter: mr.hitterProfile(flyBat), statType: 'hits' }).multiplier).toBe(1);
    expect(mr.matchupMultiplier({ arsenal: SINKER_ARM, hitter: null, statType: 'hits' }).multiplier).toBe(1);
  });
  it('the total matchup lean is bounded', () => {
    const m = mr.matchupMultiplier({ arsenal: SINKER_ARM, hitter: mr.hitterProfile(whiffBat), statType: 'total_bases' });
    expect(Math.abs(m.multiplier - 1)).toBeLessThanOrEqual(mr.TOTAL_MAX + 1e-9);
  });
});

describe('park RELATIVE to own exposure (Phase B fix)', () => {
  it('baseline is the mean park factor over home(own)/away(opp) games', () => {
    // NYY home park (parkBase) + away games; just assert it resolves a number
    // from ≥3 venues and stays near 1.0 (park factors are ~1.0).
    const log = [
      { isHome: true, opponent: 'Boston Red Sox', stat: {} },
      { isHome: false, opponent: 'Boston Red Sox', stat: {} },
      { isHome: false, opponent: 'Houston Astros', stat: {} },
      { isHome: true, opponent: 'Tampa Bay Rays', stat: {} },
    ];
    const b = pc.parkBaselineFromLogs(log, 'NYY');
    if (b != null) { expect(b).toBeGreaterThan(0.7); expect(b).toBeLessThan(1.3); }
  });
  it('too few resolvable venues → null (park contributes nothing, not a raw multiply)', () => {
    expect(pc.parkBaselineFromLogs([{ isHome: true, stat: {} }], 'NYY')).toBeNull();
  });
});

describe('projectProp — full object, never abstains, plausible', () => {
  const hitLog = (vals) => vals.map((h) => ({ isHome: true, opponent: 'Boston Red Sox', stat: { hits: h } }));

  it('emits distribution + full ladder + point + factor breakdown', () => {
    // fair_prob 0.55 = the de-vigged fair the grade carries (NOT raw book)
    const grade = { stat_type: 'hits', line: 0.5, direction: 'over', season_avg: 0.9, fair_prob: 0.55, book_odds: -150, team: 'NYY' };
    const p = pc.projectProp({ grade, gameLog: hitLog([1, 0, 2, 1, 1, 0, 1, 2, 1, 0]) });
    expect(p.proj_version).toBe('proj-v1.1');
    expect(p.proj_distribution.family).toBe('negative_binomial');
    expect(p.proj_ladder.length).toBeGreaterThanOrEqual(3);
    expect(p.proj_ladder[0].p_at_least).toBeGreaterThanOrEqual(p.proj_ladder[1].p_at_least);
    expect(p.proj_factors.breakdown.map((f) => f.label)).toEqual(
      expect.arrayContaining(['park_relative', 'weather', 'platoon', 'matchup']),
    );
    // traded rung carries DE-VIGGED FAIR (not raw book) for the comparison
    expect(p.proj_ladder.find((r) => r.rung === 1).book_implied).toBeCloseTo(0.55, 3);
    expect(p.proj_book_implied).toBeCloseTo(0.55, 3);
    expect(p.proj_factors.book_implied_basis).toBe('fair_multiplicative');
    expect(p.proj_p_over_line).toBeGreaterThan(0);
  });

  it('book implied is de-vigged FAIR on the OVER basis for an under prop', () => {
    // under prop, fair_prob 0.6 (fair the ball stays under) → over-basis fair 0.4
    const grade = { stat_type: 'hits', line: 1.5, direction: 'under', season_avg: 0.9, fair_prob: 0.6, team: 'NYY' };
    const p = pc.projectProp({ grade, gameLog: hitLog([1, 0, 2, 1, 1, 0, 1, 2, 1, 0]) });
    expect(p.proj_book_implied).toBeCloseTo(0.4, 3);
    expect(p.proj_factors.book_implied_basis).toBe('fair_multiplicative');
  });

  it('HONEST-NULL when fair is uncomputable — never a raw-book fallback', () => {
    // one-sided market: book_odds present but NO fair_prob → book_implied null
    const grade = { stat_type: 'hits', line: 0.5, direction: 'over', season_avg: 0.9, book_odds: -150, team: 'NYY' };
    const p = pc.projectProp({ grade, gameLog: hitLog([1, 0, 2, 1, 1, 0, 1, 2, 1, 0]) });
    expect(p.proj_book_implied).toBeNull(); // NOT 0.6 from raw book
    expect(p.proj_ladder.find((r) => r.rung === 1).book_implied).toBeNull();
    expect(p.proj_factors.book_implied_basis).toBe('none');
  });

  it('flags the longshot de-vig caveat where multiplicative bias is largest', () => {
    const grade = { stat_type: 'home_runs', line: 0.5, direction: 'over', season_avg: 0.2, fair_prob: 0.18, team: 'NYY' };
    const p = pc.projectProp({ grade, gameLog: hitLog([0, 0, 1, 0, 0, 1, 0, 0, 0, 1]) });
    expect(p.proj_factors.longshot_devig_caveat).toBe(true);
  });

  it('NEVER abstains — an empty game log still projects (wide, from the prior)', () => {
    const grade = { stat_type: 'hits', line: 0.5, direction: 'over', season_avg: 0.9, team: 'NYY' };
    const p = pc.projectProp({ grade, gameLog: [] });
    expect(p.proj_point).not.toBeNull();
    expect(p.proj_ladder[0].p_at_least).toBeGreaterThan(0);
  });

  it('PLAUSIBILITY: a .300-ish hitter does not project 3.0 hits', () => {
    const grade = { stat_type: 'hits', line: 1.5, direction: 'over', season_avg: 0.95, team: 'NYY' };
    const p = pc.projectProp({ grade, gameLog: hitLog([1, 1, 2, 0, 1, 1, 1, 0, 2, 1]) });
    expect(p.proj_point).toBeLessThan(2.0);
    expect(p.proj_point).toBeGreaterThan(0.5);
  });

  it('the combined non-form multiplier is bounded (no absurd Coors swing)', () => {
    const grade = { stat_type: 'home_runs', line: 0.5, direction: 'over', season_avg: 0.2, team: 'COL' };
    const p = pc.projectProp({
      grade, gameLog: hitLog([0, 0, 1, 0, 0, 1, 0, 0, 0, 1]),
      tonightParkFactor: 1.3, weatherMod: 1.1, platoonMult: 1.1, arsenal: FB_ARM,
      batterRow: flyBat,
    });
    expect(Math.abs(p.proj_factors.combined_multiplier - 1)).toBeLessThanOrEqual(pc.COMBINED_MAX + 1e-9);
  });

  it('non-batting stat → not modeled (returns null projection object)', () => {
    expect(pc.projectProp({ grade: { stat_type: 'pitcher_strikeouts', line: 5.5, direction: 'over' } })).toBeNull();
  });
});

describe('attachProjection — champion byte-identical', () => {
  it('adds proj-v1 fields, never mutates p_win / grade / other challengers', async () => {
    const grades = [{
      player: 'Slugger', playerId: null, stat_type: 'hits', line: 0.5, direction: 'over',
      season_avg: 0.9, fair_prob: 0.6, team: 'NYY', p_win: 0.58, grade: 'B',
      p_win_challenger: 0.6, p_win_contact: 0.61,
    }];
    const out = await pc.attachProjection(grades, {});
    expect(out[0].p_win).toBe(0.58);
    expect(out[0].grade).toBe('B');
    expect(out[0].p_win_challenger).toBe(0.6);
    expect(out[0].p_win_contact).toBe(0.61);
    expect(out[0].proj_version).toBe('proj-v1.1');
    expect(out[0].proj_point).not.toBeNull(); // projected even with no game log
  });
});

describe('hits-v1 — the challenger rides alongside, and reads the RIGHT takeable axis', () => {
  // A real log: at-bat counts AND hits, which the negative-binomial path never
  // asks for. Most recent LAST (statsapi order).
  const abLog = (pairs) => pairs.map(([ab, h]) => ({ isHome: true, opponent: 'Boston Red Sox', stat: { atBats: ab, hits: h } }));
  const LOG = abLog([[4, 1], [3, 0], [5, 2], [4, 1], [4, 0], [3, 1], [4, 2], [4, 1], [3, 1], [4, 0]]);

  it('emits proj_hits_p_over WITHOUT disturbing the current ladder or the champion', () => {
    const grade = { stat_type: 'hits', line: 0.5, direction: 'over', season_avg: 0.9, fair_prob: 0.55, team: 'NYY', book: 'draftkings', over_odds: -150, under_odds: 130 };
    const withHits = pc.projectProp({ grade, gameLog: LOG });
    // The ladder value is computed from the SAME log by the SAME code path as
    // before this challenger existed — hits-v1 is additive, never substitutive.
    expect(withHits.proj_hits_p_over).toBeGreaterThan(0);
    expect(withHits.proj_hits_p_over).toBeLessThanOrEqual(1);
    expect(withHits.proj_p_over_line).not.toBeNull();
    expect(withHits.proj_distribution.family).toBe('negative_binomial');
    expect(withHits.proj_hits_meta.version).toBe('hits-v1');
    expect(withHits.proj_hits_meta.family).toBe('binomial_over_empirical_at_bats');
  });

  it('MODELS a -300 one-sided hits market — takeable by identity, outside the promotion band', () => {
    // The whole reason the three questions were disambiguated. A -300 hits-over
    // from a real book is a bet you can place: steep juice is a PRICE, not a
    // disqualification, and one-sidedness is normal baseball market structure.
    const grade = { stat_type: 'hits', line: 0.5, direction: 'over', season_avg: 0.9, team: 'NYY', book: 'betrivers', over_odds: -300, under_odds: null };
    const p = pc.projectProp({ grade, gameLog: LOG });
    expect(p.proj_hits_p_over).not.toBeNull();          // MODELLED, not thrown away
    const m = p.proj_hits_meta.market;
    expect(m.market_takeable).toBe(true);               // identity: yes
    expect(m.within_promotion_band).toBe(false);        // price band: no
    expect(m.one_sided).toBe(true);                     // normal, not an error
    expect(m.price_filtered).toBe(false);               // no price-shape gate ran
  });

  it('a longshot +1300 hits market is still modelled — recording is not crowning', () => {
    const grade = { stat_type: 'hits', line: 2.5, direction: 'over', season_avg: 0.9, team: 'NYY', book: 'fanduel', over_odds: 1300, under_odds: -2000 };
    const p = pc.projectProp({ grade, gameLog: LOG });
    expect(p.proj_hits_p_over).not.toBeNull();
    expect(p.proj_hits_meta.market.market_takeable).toBe(true);
    expect(p.proj_hits_meta.market.within_promotion_band).toBe(false);
  });

  it('never reads the deprecated `takeable` mirror', () => {
    const src = require('fs').readFileSync(require.resolve('../../src/services/projection/binomialHits'), 'utf8')
      + require('fs').readFileSync(require.resolve('../../src/services/projectionChallenger'), 'utf8');
    // The disambiguated names only. `takeable:` as a bare field read would be
    // the ambiguous mirror the S-prior commit deprecated.
    expect(/\btakeable\s*:/.test(src.replace(/market_takeable\s*:/g, ''))).toBe(false);
  });

  it('is NULL on a non-hits prop — never a fabricated 0', () => {
    const grade = { stat_type: 'total_bases', line: 1.5, direction: 'over', season_avg: 1.4, team: 'NYY', book: 'draftkings', over_odds: -110 };
    const p = pc.projectProp({ grade, gameLog: LOG });
    expect(p.proj_hits_p_over).toBeNull();
    expect(p.proj_hits_meta).toBeNull();
  });

  it('abstains honestly when the at-bat inputs are underivable, keeping the ladder', () => {
    // A log with hits but no at-bat counts — exactly what the NB path runs on.
    const noAb = [1, 0, 2, 1, 1, 0, 1].map((h) => ({ isHome: true, opponent: 'Boston Red Sox', stat: { hits: h } }));
    const grade = { stat_type: 'hits', line: 0.5, direction: 'over', season_avg: 0.9, team: 'NYY', book: 'draftkings', over_odds: -140 };
    const p = pc.projectProp({ grade, gameLog: noAb });
    expect(p.proj_hits_p_over).toBeNull();                  // no read, not a zero
    expect(p.proj_hits_meta.reason).toBe('inputs_underivable');
    expect(p.proj_p_over_line).not.toBeNull();              // the ladder still stands
  });
});