---
title: "Place a sound effect on one beat."
method: POST
path: "/trailers/{jobId}/storyboard/sfx"
tags: ["Trailer"]
---

# Place a sound effect on one beat.

`POST /trailers/{jobId}/storyboard/sfx`

## Request

- Base URL: `https://docs.sleeperhit.studio/api/v1`
- URL: `https://docs.sleeperhit.studio/api/v1/trailers/{jobId}/storyboard/sfx`
- Auth: HTTP bearer

One endpoint, selected by `action`: `add` generates a new cue from a prompt, `apply-library` places a track already in My Library (no generation, and the only way a recurring motif sounds IDENTICAL every time), `update` moves, relevels or disables a placed cue, `remove` deletes it. Offsets are measured from the beat's own start. Generating — `add` — waits for the project's gate: while it is closed the call is refused with 409 `project_precondition_failed` and nothing is generated or placed; `apply-library`, `update` and `remove` generate nothing and stay open. Requires `Idempotency-Key`. Scope: `story:write`.

## Headers

- `Idempotency-Key` string, required

## Request body

- object
  - `action` 'add' | 'update' | 'remove' | 'apply-library', required
  - `sceneIndex` integer, required: Zero-based index of the beat.

## Response `200`

The placed cue, plus a shareable per-beat preview link.

- object

## Other responses

- `400`: Request payload failed validation. The error message names the offending field.
- `401`: Missing, malformed, revoked, or expired API key.
- `403`: API key is valid but lacks the scope, is blocked by IP allowlist, or the account is disabled.
- `404`: The named project or source does not exist or is owned by another account.
- `429`: Rate limit for this API key + IP + route family was exceeded.
- `500`: The API failed unexpectedly. Safe to retry with the same Idempotency-Key.

---

[API](https://skmtc.dev/sleeperhit/apis/sleeper-hit-studio-story-api.md) · [All operations](https://skmtc.dev/sleeperhit/apis/sleeper-hit-studio-story-api/llms.txt) · [OpenAPI document](https://skmtc.dev/sleeperhit/apis/sleeper-hit-studio-story-api/revisions/4534f5d25540?raw)