feat(cli): expose png-sequence format

The producer already supports `format: "png-sequence"` end-to-end (see
RenderConfig in renderOrchestrator.ts), but the CLI's VALID_FORMAT
validator rejects it before the flag reaches the producer. Surface it
the same way `mov` and `webm` are surfaced.

Behaviour:
- `--format png-sequence` accepted alongside mp4/webm/mov.
- Auto-output path uses no extension (FORMAT_EXT["png-sequence"] = "")
  since the producer treats outputPath as a directory of frame_NNNNNN.png.
- `printRenderComplete` sums the contained file sizes when outputPath
  is a directory, instead of reporting the platform-dependent inode
  size.
- DockerRenderOptions.format type extended; existing buildDockerRunArgs
  is unchanged because it forwards the string verbatim.

Tests:
- renderLocal forwards `format: "png-sequence"` to createRenderJob.
- buildDockerRunArgs propagates `--format png-sequence` to the
  container.

Docs:
- Rendering guide: format flag table, format comparison table, new
  "PNG sequence (no encoding)" section, "How it works" extended.
- CLI package docs: format flag table updated.

docs/guides/rendering.mdx

@@ -116,7 +116,7 @@ Render your Hyperframes [compositions](/concepts/compositions) to MP4, MOV, or W
 | Flag | Values | Default | Description |
 |------|--------|---------|-------------|
 | `--output` | path | `renders/<name>.mp4` | Output file path |
-| `--format` | mp4, mov, webm | mp4 | Output format (see [Transparent Video](#transparent-video) below) |
+| `--format` | mp4, mov, webm, png-sequence | mp4 | Output format (see [Transparent Video](#transparent-video) below) |
 | `--fps` | 24, 30, 60 | 30 | Frames per second |
 | `--quality` | draft, standard, high | standard | Encoding quality preset |
 | `--crf` | 0–51 | — | Override CRF (lower = higher quality). Cannot combine with `--video-bitrate` |
@@ -301,19 +301,28 @@ npx hyperframes render --format mov --output overlay.mov
 |--------|-------|-------------|---------------|----------|-----------|
 | **MOV** | ProRes 4444 | Yes | CapCut, Final Cut, Premiere, DaVinci, After Effects | No | Large |
 | **WebM** | VP9 | Yes | None (shows black background) | Chrome, Firefox | Small |
+| **PNG sequence** | RGBA PNGs (no encoding) | Yes (lossless) | After Effects, Nuke, Fusion (image-sequence import) | No | Largest |
 | **MP4** | H.264 | No | All | All | Small |
 
 <Note>
   **WebM VP9 alpha** is technically supported but all major video editors ignore the alpha channel and render transparent areas as black. Only Chromium-based browsers (Chrome, Arc, Brave, Edge) decode VP9 alpha correctly. Safari does not support it. Use MOV for editor workflows and WebM only for browser-based playback.
 </Note>
 
+### PNG sequence (no encoding)
+
+```bash Terminal
+npx hyperframes render --format png-sequence --output frames/
+```
+
+`--format png-sequence` skips the encoder entirely. The captured RGBA frames are copied to `<output>/frame_NNNNNN.png` (zero-padded) and, if the composition has audio, an `audio.aac` sidecar is written alongside. Use this when you want lossless frames — for compositing in After Effects / Nuke / Fusion, or as the input to a custom encode pipeline. `--output` is treated as a directory and is created if it doesn't exist.
+
 ### How it works
 
-When you render with `--format mov` or `--format webm`, Hyperframes:
+When you render with `--format mov`, `--format webm`, or `--format png-sequence`, Hyperframes:
 
 1. Captures each frame as a **PNG with alpha channel** (instead of JPEG for MP4)
 2. Sets Chrome's page background to transparent via `Emulation.setDefaultBackgroundColorOverride`
-3. Encodes with an alpha-capable codec (ProRes 4444 for MOV, VP9 for WebM)
+3. Encodes with an alpha-capable codec (ProRes 4444 for MOV, VP9 for WebM); `png-sequence` skips encoding and writes the captured frames directly
 
 Your composition's HTML should **not** set a `background` on `html` or `body` — leave it unset so the transparent background comes through.
 

docs/packages/cli.mdx

@@ -604,7 +604,7 @@ This is suppressed in CI environments, non-TTY shells, and when `HYPERFRAMES_NO_
     | Flag | Values | Default | Description |
     |------|--------|---------|-------------|
     | `--output` | path | `renders/<name>.mp4` | Output file path |
-    | `--format` | mp4, webm, mov | mp4 | Output format (WebM/MOV render with transparency) |
+    | `--format` | mp4, webm, mov, png-sequence | mp4 | Output format (WebM/MOV render with transparency; png-sequence writes a directory of RGBA PNGs) |
     | `--fps` | 24, 30, 60 | 30 | Frames per second |
     | `--quality` | draft, standard, high | standard | Encoding quality preset (drives CRF/bitrate) |
     | `--crf` | 0-51 | — | Override encoder CRF (lower = higher quality). Mutually exclusive with `--video-bitrate` |

packages/cli/src/commands/render.test.ts

@@ -143,6 +143,21 @@ describe("renderLocal browser GPU config", () => {
     expect(producerState.createdJobs[0]?.variables).toEqual({ title: "Hello", count: 3 });
   });
 
+  it("forwards format: png-sequence through to createRenderJob", async () => {
+    const { renderLocal } = await import("./render.js");
+    await renderLocal("/tmp/project", "/tmp/frames", {
+      fps: 30,
+      quality: "standard",
+      format: "png-sequence",
+      gpu: false,
+      browserGpuMode: "software",
+      hdrMode: "auto",
+      quiet: true,
+    });
+
+    expect(producerState.createdJobs[0]?.format).toBe("png-sequence");
+  });
+
   it("omits variables from createRenderJob when not provided", async () => {
     const { renderLocal } = await import("./render.js");
     await renderLocal("/tmp/project", "/tmp/out.mp4", {
@@ -165,7 +180,7 @@ describe("renderLocal browser GPU config", () => {
       quality: "standard",
       format: "mp4",
       gpu: false,
-      browserGpu: false,
+      browserGpuMode: "software",
       hdrMode: "auto",
       quiet: true,
       entryFile: "compositions/intro.html",
@@ -181,7 +196,7 @@ describe("renderLocal browser GPU config", () => {
       quality: "standard",
       format: "mp4",
       gpu: false,
-      browserGpu: false,
+      browserGpuMode: "software",
       hdrMode: "auto",
       quiet: true,
     });

packages/cli/src/commands/render.ts

@@ -1,12 +1,16 @@
 import { defineCommand } from "citty";
 import type { Example } from "./_examples.js";
-import { mkdirSync, readFileSync, statSync, writeFileSync, rmSync } from "node:fs";
+import { mkdirSync, readdirSync, readFileSync, statSync, writeFileSync, rmSync } from "node:fs";
 
 export const examples: Example[] = [
   ["Render to MP4", "hyperframes render --output output.mp4"],
   ["Render a specific composition", "hyperframes render -c compositions/intro.html -o intro.mp4"],
   ["Render transparent overlay (ProRes)", "hyperframes render --format mov --output overlay.mov"],
   ["Render transparent WebM overlay", "hyperframes render --format webm --output overlay.webm"],
+  [
+    "Render PNG sequence (RGBA frames for AE/Nuke/Fusion)",
+    "hyperframes render --format png-sequence --output frames/",
+  ],
   ["High quality at 60fps", "hyperframes render --fps 60 --quality high --output hd.mp4"],
   ["Deterministic render via Docker", "hyperframes render --docker --output deterministic.mp4"],
   ["Parallel rendering with 6 workers", "hyperframes render --workers 6 --output fast.mp4"],
@@ -47,15 +51,22 @@ import {
 
 const VALID_FPS = new Set([24, 30, 60]);
 const VALID_QUALITY = new Set(["draft", "standard", "high"]);
-const VALID_FORMAT = new Set(["mp4", "webm", "mov"]);
+const VALID_FORMAT = new Set(["mp4", "webm", "mov", "png-sequence"]);
-const FORMAT_EXT: Record<string, string> = { mp4: ".mp4", webm: ".webm", mov: ".mov" };
+// `png-sequence` writes a directory of frames rather than a single muxed file,
+// so its "extension" is empty — the auto-output path becomes a directory name.
+const FORMAT_EXT: Record<string, string> = {
+  mp4: ".mp4",
+  webm: ".webm",
+  mov: ".mov",
+  "png-sequence": "",
+};
 
 const CPU_CORE_COUNT = cpus().length;
 
 export default defineCommand({
   meta: {
     name: "render",
-    description: "Render a composition to MP4, WebM, or MOV",
+    description: "Render a composition to MP4, WebM, MOV, or a PNG sequence",
   },
   args: {
     dir: {
@@ -89,7 +100,10 @@ export default defineCommand({
     },
     format: {
       type: "string",
-      description: "Output format: mp4, webm, mov (MOV/WebM render with transparency)",
+      description:
+        "Output format: mp4, webm, mov, png-sequence " +
+        "(MOV/WebM render with transparency; png-sequence writes RGBA frames " +
+        "to a directory for AE/Nuke/Fusion ingest)",
       default: "mp4",
     },
     workers: {
@@ -187,10 +201,10 @@ export default defineCommand({
     // ── Validate format ─────────────────────────────────────────────────
     const formatRaw = args.format ?? "mp4";
     if (!VALID_FORMAT.has(formatRaw)) {
-      errorBox("Invalid format", `Got "${formatRaw}". Must be mp4, webm, or mov.`);
+      errorBox("Invalid format", `Got "${formatRaw}". Must be mp4, webm, mov, or png-sequence.`);
       process.exit(1);
     }
-    const format = formatRaw as "mp4" | "webm" | "mov";
+    const format = formatRaw as "mp4" | "webm" | "mov" | "png-sequence";
 
     // ── Validate workers ──────────────────────────────────────────────────
     let workers: number | undefined;
@@ -464,7 +478,7 @@ export default defineCommand({
 interface RenderOptions {
   fps: 24 | 30 | 60;
   quality: "draft" | "standard" | "high";
-  format: "mp4" | "webm" | "mov";
+  format: "mp4" | "webm" | "mov" | "png-sequence";
   workers?: number;
   gpu: boolean;
   /**
@@ -976,7 +990,24 @@ function printRenderComplete(outputPath: string, elapsedMs: number, quiet: boole
 
   let fileSize = "unknown";
   try {
-    fileSize = formatBytes(statSync(outputPath).size);
+    const stat = statSync(outputPath);
+    if (stat.isDirectory()) {
+      // png-sequence output is a directory; sum the contained file sizes so
+      // the user sees the on-disk footprint of the deliverable rather than
+      // the platform-specific size of the directory inode itself.
+      let total = 0;
+      for (const entry of readdirSync(outputPath, { withFileTypes: true })) {
+        if (!entry.isFile()) continue;
+        try {
+          total += statSync(join(outputPath, entry.name)).size;
+        } catch {
+          // skip unreadable entries
+        }
+      }
+      fileSize = formatBytes(total);
+    } else {
+      fileSize = formatBytes(stat.size);
+    }
   } catch {
     // file doesn't exist or is inaccessible
   }

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

@@ -181,6 +181,17 @@ describe("buildDockerRunArgs", () => {
     expect(args).toContain("compositions/intro.html");
   });
 
+  it("forwards --format png-sequence to the container", () => {
+    const args = buildDockerRunArgs({
+      ...FIXED_INPUT,
+      outputFilename: "frames",
+      options: { ...BASE, format: "png-sequence" },
+    });
+    const formatIdx = args.indexOf("--format");
+    expect(formatIdx).toBeGreaterThanOrEqual(0);
+    expect(args[formatIdx + 1]).toBe("png-sequence");
+  });
+
   it("forwards --video-bitrate to the container when set", () => {
     const args = buildDockerRunArgs({
       ...FIXED_INPUT,

packages/cli/src/utils/dockerRunArgs.ts

@@ -21,7 +21,7 @@ export interface DockerRunArgsInput {
 export interface DockerRenderOptions {
   fps: 24 | 30 | 60;
   quality: "draft" | "standard" | "high";
-  format: "mp4" | "webm" | "mov";
+  format: "mp4" | "webm" | "mov" | "png-sequence";
   workers?: number;
   gpu: boolean;
   browserGpu: boolean;