---
# @generated by sylphx-gen 0.1.0 from contracts@e145cc7cf1bc9605f2b27439e5e17ed76a1a2fd7e7021906a013f7565e4a0cd5. Do not edit.
title: "Start batch on a run"
description: "`workflows.runs.start_batch` (POST /v1/{parent}/runs:startBatch): Starts a batch: a parent Run that fans out one child Run per item, each with a stable index and count."
type: reference
product: workflows
summary: "Starts a batch: a parent Run that fans out one child Run per item, each with a stable index and count."
updated: 2026-09-28
nav: false
---

> **This method is not served on the public API.** `api.sylphx.com` does not route this call: its backend is not deployed behind the public API, or does not implement the call. This page documents the contract. It is kept out of the sidebar and of search engines.

Starts a batch: a parent Run that fans out one child Run per item, each with a stable index and count.

- **Path** `POST https://api.sylphx.com/v1/orgs/acme/projects/shop/envs/production/workflows/workflow/runs:startBatch`
- **Scope** `workflows:run`
- **Effect** `write` — a successful call changes state.
- **Collection** [runs](/docs/api/runs)

## Request

| Field | Type | What it is |
| --- | --- | --- |
| `parent` | `string` | The parent the method acts in. Required. |
| `inputs` | `struct[]` | The inputs, one child Run each; at most 10 000. Required. |
| `max_concurrency` | `int32` | At most this many children run at once; 0 is the Workflow's limit. |

## Response

| Field | Type | What it is |
| --- | --- | --- |
| `run` | `Run` | The parent batch Run. |

### Run

| Field | Type | What it is |
| --- | --- | --- |
| `name` | `string` | `orgs/{org}/projects/{project}/envs/{env}/workflows/{workflow}/runs/{run}`. |
| `uid` | `string` | `run_<cell><ulid>`; never reused. Output only. |
| `meta` | `ResourceMeta` | Resource metadata. |
| `workflow_generation` | `int64` | The Workflow generation the Run pinned at start. Output only. |
| `input` | `struct` | The Run input, at most 256 KiB of JSON. |
| `start_delay` | `duration` | Delay the first invocation by this much. |
| `state` | `RunState` | The Run's lifecycle state. Output only. One of `running`, `succeeded`, `failed`, `cancelled`, `timed_out`. |
| `schedule_fire` | `ScheduleFireRef` | Set when a Schedule fire started the Run. Output only. |
| `batch_position` | `BatchPosition` | Set on a child of a batch Run. Output only. |
| `start_time` | `timestamp` | When the Run started. Output only. |
| `end_time` | `timestamp` | When the Run closed. Output only. |
| `attempt_count` | `int32` | Attempts made so far, across every step. Output only. |
| `output` | `struct` | The handler's `complete` output, once `succeeded`. Output only. |
| `error` | `RunError` | The failure, once `failed` or `timed_out`. Output only. |
| `schedule_time` | `timestamp` | When the first invocation is due: set it directly, or through `start_delay`; at most 365 days ahead. A Run cancelled before then closes `cancelled` with no invocation. |

### ResourceMeta

| Field | Type | What it is |
| --- | --- | --- |
| `generation` | `int64` | Increases by one on every change to `spec`. Output only. |
| `etag` | `string` | Strong ETag (AIP-154): changes on any change to spec, status, or metadata. Send it back as `If-Match` or `etag` to make Update and Delete conditional; a mismatch fails with ABORTED / 409 `ETAG_MISMATCH`. Output only. |
| `create_time` | `timestamp` | When the Resource was created. Output only. |
| `update_time` | `timestamp` | When the Resource last changed. Output only. |
| `delete_time` | `timestamp` | Set while the Resource is being deleted. Output only. |
| `labels` | `map<string, string>` | Caller-writable, indexed labels (AIP-122 label rules). |
| `annotations` | `map<string, string>` | Caller-writable, unindexed annotations. |
| `display_name` | `string` | Caller-writable human-readable name. |
| `creator` | `string` | The principal that created the Resource. Output only. |

### ScheduleFireRef

| Field | Type | What it is |
| --- | --- | --- |
| `schedule` | `string` | The Schedule. Output only. |
| `intended_time` | `timestamp` | The instant the fire was due. Output only. |

### BatchPosition

| Field | Type | What it is |
| --- | --- | --- |
| `parent_run` | `string` | The parent batch Run. Output only. |
| `index` | `int32` | Zero-based index of this child. Output only. |
| `total_count` | `int32` | Number of children in the batch. Output only. |

### RunError

| Field | Type | What it is |
| --- | --- | --- |
| `code` | `string` | A machine-readable code, for example `handler_rejected` or `card_declined`. Output only. |
| `message` | `string` | A customer-safe message. Output only. |
| `retryable` | `bool` | Whether the handler marked the failure retryable. Output only. |

## Errors

- [`UNAUTHENTICATED`](/docs/api/errors/UNAUTHENTICATED) — No valid key or token was presented.
- [`PERMISSION_DENIED`](/docs/api/errors/PERMISSION_DENIED) — The key lacks the method's permission.
- [`RESOURCE_NOT_FOUND`](/docs/api/errors/RESOURCE_NOT_FOUND) — The named Resource does not exist or is not visible.
- [`INVALID_FIELD`](/docs/api/errors/INVALID_FIELD) — A field failed validation.
- [`IDEMPOTENCY_KEY_REUSED`](/docs/api/errors/IDEMPOTENCY_KEY_REUSED) — An Idempotency-Key was reused with another body.
- [`IDEMPOTENCY_IN_PROGRESS`](/docs/api/errors/IDEMPOTENCY_IN_PROGRESS) — The first call with this Idempotency-Key is still running.
- [`RATE_LIMITED`](/docs/api/errors/RATE_LIMITED) — The rate limit is reached; see Retry-After.
- [`PLAN_LIMIT_REACHED`](/docs/api/errors/PLAN_LIMIT_REACHED) — The plan's limit is reached.

Every error arrives in the body [Errors](/docs/platform/errors) describes.

## Examples

**cURL**

```curl
curl -X POST "https://api.sylphx.com/v1/orgs/acme/projects/shop/envs/production/workflows/workflow/runs:startBatch" \
  -H "Authorization: Bearer $SYLPHX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"inputs":[{}]}'
```

**TypeScript**

```ts
const response = await sylphx.workflows.runs.startBatch({ inputs: [{}], parent: 'orgs/acme/projects/shop/envs/production/workflows/workflow' })
```

**Rust**

```rust
let mut req = sylphx::workflows::StartRunBatchRequest::default();
req.inputs = vec![Default::default()];
req.parent = "orgs/acme/projects/shop/envs/production/workflows/workflow".to_string();
let response = sx.workflows().runs().start_batch(req).await?;
```

**CLI**

```bash
sylphx workflows runs start-batch orgs/acme/projects/shop/envs/production/workflows/workflow
```

**MCP**

```json
{ "method_id": "workflows.runs.start_batch", "args": {"inputs":[{}],"parent":"orgs/acme/projects/shop/envs/production/workflows/workflow"} }
```