fix: budget workers for expensive captures

packages/cli/src/commands/render.ts

@@ -35,11 +35,6 @@ const FORMAT_EXT: Record<string, string> = { mp4: ".mp4", webm: ".webm", mov: ".
 
 const CPU_CORE_COUNT = cpus().length;
 
-/** 3/4 of CPU cores, capped at 8. Each worker spawns a Chrome process (~256 MB). */
-function defaultWorkerCount(): number {
-  return Math.max(1, Math.min(Math.floor((CPU_CORE_COUNT * 3) / 4), 8));
-}
-
 export default defineCommand({
   meta: {
     name: "render",
@@ -216,12 +211,9 @@ export default defineCommand({
     }
 
     // ── Print render plan ─────────────────────────────────────────────────
-    const workerCount = workers ?? defaultWorkerCount();
     if (!quiet) {
       const workerLabel =
-        args.workers != null
-          ? `${workerCount} workers`
-          : `${workerCount} workers (auto — ${CPU_CORE_COUNT} cores detected)`;
+        workers != null ? `${workers} workers` : `auto workers (${CPU_CORE_COUNT} cores detected)`;
       console.log("");
       console.log(
         c.accent("\u25C6") +
@@ -307,7 +299,7 @@ export default defineCommand({
         fps,
         quality,
         format,
-        workers: workerCount,
+        workers,
         gpu: useGpu,
         hdr: args.hdr ?? false,
         crf,
@@ -319,7 +311,7 @@ export default defineCommand({
         fps,
         quality,
         format,
-        workers: workerCount,
+        workers,
         gpu: useGpu,
         hdr: args.hdr ?? false,
         crf,
@@ -335,7 +327,7 @@ interface RenderOptions {
   fps: 24 | 30 | 60;
   quality: "draft" | "standard" | "high";
   format: "mp4" | "webm" | "mov";
-  workers: number;
+  workers?: number;
   gpu: boolean;
   hdr: boolean;
   crf?: number;
@@ -604,7 +596,7 @@ function trackRenderMetrics(
     durationMs: elapsedMs,
     fps: options.fps,
     quality: options.quality,
-    workers: options.workers,
+    workers: options.workers ?? perf?.workers,
     docker,
     gpu: options.gpu,
     compositionDurationMs,

packages/cli/src/telemetry/events.ts

@@ -8,7 +8,7 @@ export function trackRenderComplete(props: {
   durationMs: number;
   fps: number;
   quality: string;
-  workers: number;
+  workers?: number;
   docker: boolean;
   gpu: boolean;
   // Composition metadata

packages/cli/src/utils/dockerRunArgs.test.ts

@@ -5,7 +5,6 @@ const BASE: DockerRenderOptions = {
   fps: 30,
   quality: "standard",
   format: "mp4",
-  workers: 4,
   gpu: false,
   hdr: false,
   crf: undefined,
@@ -43,17 +42,28 @@ describe("buildDockerRunArgs", () => {
         "standard",
         "--format",
         "mp4",
-        "--workers",
-        "4",
       ]
     `);
   });
 
+  it("omits --workers when auto sizing should happen inside the container", () => {
+    const args = buildDockerRunArgs({ ...FIXED_INPUT, options: BASE });
+    expect(args).not.toContain("--workers");
+  });
+
   it("matches snapshot when every renderer flag is enabled", () => {
     expect(
       buildDockerRunArgs({
         ...FIXED_INPUT,
-        options: { ...BASE, gpu: true, hdr: true, crf: 18, videoBitrate: undefined, quiet: true },
+        options: {
+          ...BASE,
+          workers: 4,
+          gpu: true,
+          hdr: true,
+          crf: 18,
+          videoBitrate: undefined,
+          quiet: true,
+        },
       }),
     ).toMatchInlineSnapshot(`
       [

packages/cli/src/utils/dockerRunArgs.ts

@@ -22,7 +22,7 @@ export interface DockerRenderOptions {
   fps: 24 | 30 | 60;
   quality: "draft" | "standard" | "high";
   format: "mp4" | "webm" | "mov";
-  workers: number;
+  workers?: number;
   gpu: boolean;
   hdr: boolean;
   crf?: number;
@@ -54,8 +54,7 @@ export function buildDockerRunArgs(input: DockerRunArgsInput): string[] {
     options.quality,
     "--format",
     options.format,
-    "--workers",
-    String(options.workers),
+    ...(options.workers != null ? ["--workers", String(options.workers)] : []),
     ...(options.crf != null ? ["--crf", String(options.crf)] : []),
     ...(options.videoBitrate ? ["--video-bitrate", options.videoBitrate] : []),
     ...(options.quiet ? ["--quiet"] : []),