ai

test/prediction-reconciliation.test.ts

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+// Reconciliation guard for the REAL client predictor. It exercises
+// LocalCharacterPredictor end-to-end with an injected clock, verifying the two
+// properties reconciliation depends on:
+//   1. a fully-acknowledged snapshot reproduces the authoritative pose exactly
+//      (no spurious drift on top of server truth), and
+//   2. un-acknowledged input is replayed forward deterministically.
+// This is the net for prediction-touching changes (the death-while-dead fix,
+// future netcode work) — a regression shows up as drift or non-determinism.
+import { describe, it, expect } from 'vitest';
+import {
+  LocalCharacterPredictor,
+  setPredictorClockForTesting,
+} from '../frontend/src/scripts/helper/prediction/local-character-predictor';
+
+const HEAD_RADIUS = 50;
+const FEET_RADIUS = 20;
+
+// A Circle-shaped pose; the predictor only reads .center / .radius, so plain
+// objects with array centres are sufficient (and avoid importing gl-matrix).
+const poseAt = (cx: number, cy: number) => ({
+  head: { center: [cx, cy + 37], radius: HEAD_RADIUS },
+  leftFoot: { center: [cx - 33, cy - 18], radius: FEET_RADIUS },
+  rightFoot: { center: [cx + 33, cy - 18], radius: FEET_RADIUS },
+});
+
+describe('local prediction reconciliation', () => {
+  it('reproduces the authoritative pose exactly when all input is acknowledged', () => {
+    let clock = 1000;
+    setPredictorClockForTesting(() => clock);
+
+    const predictor = new LocalCharacterPredictor();
+    const auth = poseAt(500, 500);
+
+    const t = predictor.recordInput([1, 0]);
+    predictor.acknowledge(t, [0, 0], -Infinity); // server has consumed this input
+    predictor.setStrength(80);
+    predictor.setAuthoritative(auth.head as never, auth.leftFoot as never, auth.rightFoot as never);
+
+    // No clock advance → zero replay window → predicted pose == authoritative.
+    const used = predictor.update([], 1 / 60);
+
+    expect(used).toBe(true);
+    expect(predictor.head.center[0]).toBeCloseTo(auth.head.center[0], 5);
+    expect(predictor.head.center[1]).toBeCloseTo(auth.head.center[1], 5);
+    expect(predictor.leftFoot.center[0]).toBeCloseTo(auth.leftFoot.center[0], 5);
+    expect(predictor.rightFoot.center[0]).toBeCloseTo(auth.rightFoot.center[0], 5);
+  });
+
+  it('replays un-acknowledged input deterministically', () => {
+    const drive = () => {
+      let clock = 0;
+      setPredictorClockForTesting(() => clock);
+
+      const predictor = new LocalCharacterPredictor();
+      clock = 1000;
+      predictor.acknowledge(900, [0, 0], -Infinity); // baseline ack (older than the input below)
+      predictor.setStrength(80);
+      const auth = poseAt(0, 0);
+      predictor.setAuthoritative(auth.head as never, auth.leftFoot as never, auth.rightFoot as never);
+      predictor.recordInput([1, 0]); // unacked rightward input at t=1000
+
+      clock = 1100; // replay ~100 ms forward
+      predictor.update([], 1 / 60);
+      return [
+        predictor.head.center[0],
+        predictor.head.center[1],
+        predictor.leftFoot.center[0],
+        predictor.rightFoot.center[0],
+      ];
+    };
+
+    const a = drive();
+    const b = drive();
+    expect(a).toEqual(b); // deterministic replay
+    expect(a.every((n) => Number.isFinite(n))).toBe(true);
+    expect(a[0]).toBeGreaterThan(0.5); // rightward input actually moved the body
+  });
+
+  it('suppresses prediction while the local player is dead', () => {
+    let clock = 5000;
+    setPredictorClockForTesting(() => clock);
+
+    const predictor = new LocalCharacterPredictor();
+    const auth = poseAt(200, 200);
+    const t = predictor.recordInput([1, 0]);
+    predictor.acknowledge(t, [0, 0], -Infinity);
+    predictor.setStrength(80);
+    predictor.setAuthoritative(auth.head as never, auth.leftFoot as never, auth.rightFoot as never);
+    predictor.setAlive(false); // dead, awaiting respawn
+
+    clock = 5200; // input + elapsed time that would otherwise be replayed forward
+    // Even with a valid authoritative pose and pending input, a dead body must
+    // not be predicted/moved — that was the "move while dead" bug.
+    expect(predictor.update([], 1 / 60)).toBe(false);
+  });
+});