> For the complete documentation index, see [llms.txt](https://ai.ortusbooks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ai.ortusbooks.com/main-components/middleware/flight-recorder.md).

# FlightRecorderMiddleware

Record and replay LLM and tool interactions to deterministic JSON fixtures

Class: `bxModules.bxai.models.middleware.core.FlightRecorderMiddleware`

Records structured LLM/tool interactions to fixture files and can replay them without live provider or tool execution.

## Features

* Three modes: `passthrough`, `record`, `replay`
* Captures LLM requests/responses and optional tool args/results
* Incremental snapshot writes for crash-safe recordings
* Strict or lenient replay matching
* Public inspection helpers: `getTape()`, `getEffectiveFixturePath()`, `reset()`

## Constructor

```javascript
middleware = new bxModules.bxai.models.middleware.core.FlightRecorderMiddleware(
    mode       : "record",
    fixturePath: "",
    fixtureDir : "/.agents/flight-recorder",
    recordTools: true,
    strict     : true
)
```

## Configuration

| Option        | Type    | Default                      | Description                                           |
| ------------- | ------- | ---------------------------- | ----------------------------------------------------- |
| `mode`        | string  | `"passthrough"`              | Operating mode: `passthrough`, `record`, `replay`     |
| `fixturePath` | string  | `""`                         | Explicit fixture path (required in replay mode)       |
| `fixtureDir`  | string  | `"/.agents/flight-recorder"` | Directory used when auto-generating fixture files     |
| `recordTools` | boolean | `true`                       | Record/replay tool interactions                       |
| `strict`      | boolean | `true`                       | Enforce exact interaction type sequence during replay |

## Hooks Used

* `beforeAgentRun`
* `afterAgentRun`
* `wrapLLMCall`
* `wrapToolCall`

## Example

```javascript
agent = aiAgent(
    name      : "weather-agent",
    middleware: [
        new bxModules.bxai.models.middleware.core.FlightRecorderMiddleware(
            mode       : "record",
            fixtureDir : "/.agents/flight-recorder",
            recordTools: true
        )
    ]
)
```

```javascript
agent = aiAgent(
    middleware: [
        new bxModules.bxai.models.middleware.core.FlightRecorderMiddleware(
            mode       : "replay",
            fixturePath: "tests/fixtures/weather-agent.json",
            strict     : true
        )
    ]
)
```

## Notes

* In replay mode, missing fixture files throw `FlightRecorder.FixtureNotFound`.
* Strict mode throws on interaction-type mismatch; lenient mode scans forward for next matching type.
* Auto-generated file names are normalized from agent name plus timestamp.


---

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