fix: a moment your athlete is not in is not your athlete's moment

packages/core/src/scoring.ts

@@ -423,6 +423,26 @@ export const scoreWindow = (
   plugin: SportPlugin,
   ts: number,
 ): WindowScore => {
+  /**
+   * Once somebody has said which child is theirs, a moment they are not in is
+   * not their moment.
+   *
+   * Two of the seven signals — `activity_near_goal` and `high_motion` — read the
+   * whole scene and never look at the athlete at all. Between them they can
+   * clear the threshold on their own, so a run with an athlete identified for
+   * 51s of a 300s game returned seven moments of which five contained no trace
+   * of him: 49s, 68s, 158s, 175s, 182s, against an athlete on screen from 218s.
+   * Every one was a real scramble near the rim, and every one was somebody
+   * else's child. That is a highlight reel of the game, which is not the thing
+   * anyone came here for.
+   *
+   * Scene signals still contribute — a scramble the athlete is *in* is exactly
+   * what to keep — they simply cannot carry a window on their own any more.
+   */
+  if (context.focal !== null && focalAt(context, ts) === null) {
+    return { ts, score: 0, reasons: [] };
+  }
+
   const weights = ruleWeights(plugin);
   const reasons: string[] = [];
   let total = 0;

packages/core/src/theirmoments.test.ts

@@ -0,0 +1,97 @@
+import { describe, expect, it } from 'vitest';
+
+import { getSport } from '@reeleel/sports';
+
+import { computeMoments, scoreWindow, buildContext } from './scoring.js';
+import type { ScoringInput, TrackSeries } from './scoring.js';
+
+/**
+ * Whose highlights are these?
+ *
+ * `activity_near_goal` and `high_motion` read the whole scene and never look at
+ * the athlete. Between them they cleared the threshold on their own, so a
+ * production run with the athlete identified from 218s returned seven moments
+ * of which five — 49s, 68s, 158s, 175s, 182s — contained no trace of him. They
+ * were real scrambles near the rim, and every one of them was somebody else's
+ * child.
+ */
+
+const DURATION = 300;
+const plugin = getSport('basketball')!;
+
+const dense = (from: number, to: number, fn: (ts: number) => { x: number; y: number }) => {
+  const out = [];
+  for (let ts = from; ts <= to; ts += 1 / 30) {
+    out.push({ ts: Number(ts.toFixed(3)), ...fn(ts), w: 60, h: 150, confidence: 0.9 });
+  }
+  return out;
+};
+
+/** The athlete, on screen only in the second half of the game. */
+const focal: TrackSeries = {
+  id: 'trk_focal',
+  className: 'player',
+  samples: dense(218, 273, (ts) => ({ x: 400 + Math.sin(ts) * 300, y: 500 })),
+};
+
+/** A crowd that is busy near the rim all game long, athlete or no athlete. */
+const crowd = Array.from({ length: 6 }, (_unused, i) => ({
+  id: `trk_crowd_${i}`,
+  className: 'player',
+  samples: dense(0, DURATION, (ts) => ({
+    x: 1450 + Math.sin(ts * 3 + i) * 90,
+    y: 250 + Math.cos(ts * 2 + i) * 80,
+  })),
+})) as TrackSeries[];
+
+const hoop: TrackSeries = {
+  id: 'trk_hoop',
+  className: 'hoop',
+  samples: dense(0, DURATION, () => ({ x: 1500, y: 200 })),
+};
+
+const input = (focalTrackIds: string[]): ScoringInput => ({
+  durationSeconds: DURATION,
+  frameWidth: 1920,
+  frameHeight: 1080,
+  focalTrackId: focalTrackIds[0] ?? null,
+  focalTrackIds,
+  tracks: [focal, ...crowd, hoop],
+});
+
+describe('a moment the athlete is not in', () => {
+  const bound = buildContext(input(['trk_focal']), plugin.targetClass);
+
+  it('scores nothing while the athlete is off screen, however busy the court', () => {
+    // 100s: six players packed under the rim, and no sign of the athlete.
+    expect(scoreWindow(bound, plugin, 100).score).toBe(0);
+    expect(scoreWindow(bound, plugin, 100).reasons).toEqual([]);
+  });
+
+  it('still scores while the athlete is on screen', () => {
+    expect(scoreWindow(bound, plugin, 240).score).toBeGreaterThan(0);
+  });
+
+  it('suggests nothing outside the athlete’s time on court', () => {
+    for (const moment of computeMoments(input(['trk_focal']), plugin)) {
+      // Pre/post roll may reach a little past them, but not to another half.
+      expect(moment.end).toBeGreaterThan(210);
+      expect(moment.start).toBeLessThan(280);
+    }
+  });
+
+  it('keeps a scramble the athlete is part of', () => {
+    // The scene signals are not banned, they just cannot carry a window alone.
+    const window = scoreWindow(bound, plugin, 240);
+    expect(window.reasons.length).toBeGreaterThan(0);
+  });
+});
+
+describe('with nobody identified', () => {
+  it('leaves the old behaviour alone', () => {
+    // Unchanged: without a focal track there is no one to be absent, and the
+    // denominator floor is what keeps scene motion from carrying a moment.
+    const context = buildContext(input([]), plugin.targetClass);
+    expect(scoreWindow(context, plugin, 100).score).toBeLessThan(plugin.moments.minScore);
+  });
+});