> ## Documentation Index
> Fetch the complete documentation index at: https://docs.posetracker.com/llms.txt
> Use this file to discover all available pages before exploring further.

# WebView messages

> postMessage contract for the PoseTracker WebView — initialization, counter, keypoints, errors, jumps, upload extras.

The hosted page sends JSON to the host. Browser embeds use `window.parent.postMessage(JSON.stringify(data), "*")`. iOS uses `webkit.messageHandlers.iosListener`. Android uses `window.webViewCallback`. **Same `type` field** in all three.

SDK apps should prefer typed callbacks (`onCounter`, `onKeypoints`, …). `onMessage` on the SDK is this classic shape. Full SDK catalog: [Events](/reference/events).

## Transport

```js theme={null}
window.addEventListener("message", (event) => {
  let msg = event.data;
  if (typeof msg === "string") {
    try { msg = JSON.parse(msg); } catch { return; }
  }
  if (msg && msg.type) handle(msg);
});
```

## Real-time boot

| `type`           | Shape                                         | When                                                                                                                    |
| ---------------- | --------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------- |
| `initialization` | `{ message, ready? }`                         | `checking you plan and access` → `accessing webcam` → `loading pose model` (`ready: false`) → `running` (`ready: true`) |
| `error`          | `{ error, message, current_count?, origin? }` | Failures. May include `webgl_unavailable`, `backend_fallback_wasm`, `backend_fallback_cpu`                              |

Live camera is `type: "initialization"` with `ready: true` and `message: "running"`.

## Pose and exercise

| `type`             | Key fields                                                                                                          |
| ------------------ | ------------------------------------------------------------------------------------------------------------------- |
| `keypoints`        | `data: [{ name, x, y, score }]` — 17 COCO joints, x/y normalized 0–1                                                |
| `angles`           | `data: { left_side, right_side }` — needs `angles=true` + paid plan                                                 |
| `counter`          | `current_count`, optional `form_score: { score, avg_score, grade }`, optional `reference_score` in reference mode   |
| `form_score`       | Convenience `{ score, avg_score, grade }`. Authoritative counted-rep grade is on `counter.form_score`               |
| `posture`          | `message`, `direction`, `requirements`, `ready`                                                                     |
| `progression`      | `value` 0–100. Flag `progression=true`                                                                              |
| `recommendations`  | `data: string[]`. Flag `recommendations=true`. Not sent for every exercise — use `counter.form_score` for the grade |
| `exercise_summary` | End of run: `counter`, optional `history[]`                                                                         |

Outside an exercise (pose-only URL), keypoints stream without extra flags. During an exercise, keypoints need `keypoints=true` + a paid plan.

## Jumps

`jump_analysis` and `air_time_jump`:

| `type`             | Notes                                            |
| ------------------ | ------------------------------------------------ |
| `jump_calibration` | `jump_analysis` only — `cmPerPixel`, `baselineY` |
| `jump_started`     | Push-off                                         |
| `jump_height`      | Live then `final`                                |
| `jump_discarded`   | `reason`, `userMessage`                          |
| `jump_result`      | Completed jump N — `jumpHeightCm`                |
| `jump_summary`     | Totals + `jumps[]`                               |

`jump_analysis` requires `userHeightCm`. Missing → `error` `jump_analysis_missing_height`.

## Upload extras

On [upload tracking](/webview/upload) only:

| `type`            | Notes                                        |
| ----------------- | -------------------------------------------- |
| `export_ready`    | `{ url }` when export is enabled and allowed |
| `keypoints_batch` | Batched keypoints for video                  |

Upload init messages differ (`loading video`, `%` progress, `Analysis completed`).

## Reference extras

When `reference=` is set, `counter` may include `reference_score`: `{ overallScore, nccScore, dtwScore, timingScore, distScore?, grade }`. See [Reference movement](/webview/reference-movement).

## Related

* [WebView query parameters](/webview/query-params)
* [SDK events](/reference/events)
* [Features & plans](/reference/features-plans)

<Note>
  **For LLMs:** WebView events are JSON with `type`. Counter field is `current_count`. SDK typed callback uses `count` / `formScore`. [https://docs.posetracker.com/webview/messages](https://docs.posetracker.com/webview/messages)
</Note>