---
name: uloop-record-input
description: "Record keyboard and mouse input during PlayMode into a JSON file. Use when you need to: (1) Capture human gameplay input for later replay, (2) Record input sequences for E2E testing, (3) Save input for bug reproduction. Captures Input System device-state diffs frame-by-frame in PlayMode and serializes them to JSON when stopped. Requires PlayMode and the New Input System."
---

# uloop record-input

Record keyboard and mouse input during PlayMode frame-by-frame into a JSON file. Captures key presses, mouse movement, clicks, and scroll events via Input System device state diffing.

## Usage

```bash
# Start recording
uloop record-input --action Start

# Start recording with key filter
uloop record-input --action Start --keys "W,A,S,D,Space"

# Stop recording and save
uloop record-input --action Stop

# Stop and save to specific path
uloop record-input --action Stop --output-path scripts/my-play.json
```

## Parameters

| Parameter | Type | Default | Description |
|-----------|------|---------|-------------|
| `--action` | enum | `Start` | `Start` - begin recording, `Stop` - stop and save |
| `--output-path` | string | auto | Save path. Auto-generates under `.uloop/outputs/InputRecordings/` |
| `--keys` | string | `""` | Comma-separated key filter. Empty = all common game keys |

## Deterministic Replay

Replay injects input frame-by-frame, so the game must also be deterministic to produce identical results. If the recording will be used for E2E tests, bug reproduction, or replay verification, read [references/deterministic-replay.md](references/deterministic-replay.md) before designing assertions or game logic.

## Prerequisites

- Unity must be in **PlayMode**
- **Input System package** must be installed (`com.unity.inputsystem`)
- Active Input Handling must be set to `Input System Package (New)` or `Both` in Player Settings

## Output

The CLI prints JSON with:
- `Success`: Whether the operation succeeded
- `Message`: Status message
- `Action`: Echoes which action was executed (`Start` or `Stop`)
- `OutputPath`: Path to saved recording (nullable; populated on `Stop` only)
- `TotalFrames`: Number of frames recorded (nullable int; populated on `Stop` only)
- `DurationSeconds`: Recording duration in seconds (nullable float; populated on `Stop` only)

The CLI output contains only these six payload fields. Internal metadata such as `Ver` is removed before printing. There is no `RecordingId`, `StartTimestamp`, `KeysCaptured`, or per-frame data in the response — frame data lives only in the JSON file at `OutputPath`.
