perf(player): p0-1c live-playback parity test via SSIM

.github/workflows/player-perf.yml

@@ -51,6 +51,9 @@ jobs:
           - shard: drift
             scenarios: drift
             runs: "3"
+          - shard: parity
+            scenarios: parity
+            runs: "3"
     steps:
       - uses: actions/checkout@v4
 
@@ -72,6 +75,18 @@ jobs:
         with:
           chrome-version: stable
 
+      # The parity scenario shells out to `ffmpeg -lavfi ssim` to score the
+      # live-playback frame against the sync-seek reference frame. ffmpeg is
+      # not on the default ubuntu-latest runner image, and a missing binary
+      # surfaces as ENOENT inside computeSsim() — informative, but cheaper
+      # to just install it here so the shard never trips on infra.
+      - name: Install ffmpeg (parity shard only)
+        if: matrix.shard == 'parity'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends ffmpeg
+          ffmpeg -version | head -n 1
+
       - name: Run player perf — ${{ matrix.shard }} (measure mode)
         working-directory: packages/player
         env:

packages/player/tests/perf/baseline.json

@@ -6,5 +6,6 @@
   "scrubLatencyP95InlineMs": 33,
   "driftMaxMs": 500,
   "driftP95Ms": 100,
+  "paritySsimMin": 0.93,
   "allowedRegressionRatio": 0.1
 }

packages/player/tests/perf/index.ts

@@ -33,6 +33,7 @@ import { runFps } from "./scenarios/02-fps.ts";
 import { runLoad } from "./scenarios/03-load.ts";
 import { runScrub } from "./scenarios/04-scrub.ts";
 import { runDrift } from "./scenarios/05-drift.ts";
+import { runParity } from "./scenarios/06-parity.ts";
 import { reportAndGate, type GateMode, type GateResult, type Metric } from "./perf-gate.ts";
 import { launchBrowser } from "./runner.ts";
 import { startServer } from "./server.ts";
@@ -41,7 +42,7 @@ const HERE = dirname(fileURLToPath(import.meta.url));
 const RESULTS_DIR = resolve(HERE, "results");
 const RESULTS_FILE = resolve(RESULTS_DIR, "metrics.json");
 
-type ScenarioId = "load" | "fps" | "scrub" | "drift";
+type ScenarioId = "load" | "fps" | "scrub" | "drift" | "parity";
 
 /**
  * Per-scenario default `runs` value when the caller didn't pass `--runs`.
@@ -76,6 +77,7 @@ const DEFAULT_RUNS: Record<ScenarioId, number> = {
   fps: 3,
   scrub: 3,
   drift: 3,
+  parity: 3,
 };
 
 type ResultsFile = {
@@ -126,7 +128,7 @@ function parseArgs(argv: string[]): ParsedArgs {
     // `mode` is consumed (measure logs regressions but never fails; enforce
     // exits non-zero on regression).
     mode: (process.env.PLAYER_PERF_MODE as GateMode) === "enforce" ? "enforce" : "measure",
-    scenarios: ["load", "fps", "scrub", "drift"],
+    scenarios: ["load", "fps", "scrub", "drift", "parity"],
     runs: null,
     fixture: null,
     headful: false,
@@ -216,6 +218,14 @@ async function main(): Promise<void> {
           fixture: args.fixture,
         });
         metrics.push(...m);
+      } else if (scenario === "parity") {
+        const m = await runParity({
+          browser,
+          origin: server.origin,
+          runs: args.runs ?? DEFAULT_RUNS.parity,
+          fixture: args.fixture,
+        });
+        metrics.push(...m);
       } else {
         console.warn(`[player-perf] unknown scenario: ${scenario}`);
       }

packages/player/tests/perf/perf-gate.ts

@@ -45,6 +45,7 @@ export type PerfBaseline = {
   scrubLatencyP95InlineMs: number;
   driftMaxMs: number;
   driftP95Ms: number;
+  paritySsimMin: number;
   allowedRegressionRatio: number;
 };