> ## Documentation Index
> Fetch the complete documentation index at: https://stagehand.readme-i18n.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Logging

> Edit the default logging behavior

Stagehand provides a [`LogLine`](https://github.com/browserbase/stagehand/blob/9605836ee6b8207ed7dc9146e12ced1c78630d59/types/log.ts#L1-L13) object. You can override the default logger by passing in a custom logger function to the constructor.

<CodeGroup>
  ```typescript TypeScript theme={null}
  const stagehand = new Stagehand({
  	logger: (logLine: LogLine) => {
  		console.log(`[${logLine.category}] ${logLine.message}`);
  	},
  });
  ```

  ```python Python theme={null}
  from stagehand import Stagehand, StagehandConfig

  def custom_logger(log_line):
      print(f"[{log_line.get('category')}] {log_line.get('message')}")

  stagehand = Stagehand(StagehandConfig(
      logger=custom_logger,
  ))
  ```
</CodeGroup>

Below is the list of fields in the `LogLine` object. `message` is the main log message content, and `auxiliary` contains parameters that can be used to provide additional context and color to the log.

<ParamField path="id" type="string" optional>
  Unique identifier for the log line
</ParamField>

<ParamField path="category" type="string" optional>
  Category/type of the log message
</ParamField>

<ParamField path="message" type="string" required>
  The main log message content
</ParamField>

<ParamField path="level" type="0 | 1 | 2" optional>
  Logging verbosity level
</ParamField>

<ParamField path="timestamp" type="string" optional>
  Timestamp of when the log was created
</ParamField>

<ParamField path="auxiliary" type="object" optional>
  Additional metadata where each key contains a `value` and `type`. The `value` will always be a string, but `type` can be `"object"`, `"string"`, `"html"`, `"integer"`, `"float"`, or `"boolean"`
</ParamField>

You can see an example of a log line in [`OpenAIClient.ts`](https://github.com/browserbase/stagehand/blob/9605836ee6b8207ed7dc9146e12ced1c78630d59/lib/llm/OpenAIClient.ts#L79-L93). You'll notice here how `auxiliary` contains a `requestId` and `cachedResponse`.

<CodeGroup>
  ```typescript TypeScript theme={null}
  this.logger({
  	category: "llm_cache",
  	message: "LLM cache hit - returning cached response",
  	level: 1,
  	auxiliary: {
  		requestId: {
  			value: options.requestId,
  			type: "string",
  		},
  		cachedResponse: {
  			value: JSON.stringify(cachedResponse),
  			type: "object",
  		},
  	}
  });
  ```

  ```python Python theme={null}
  import json

  self.logger({
      "category": "llm_cache",
      "message": "LLM cache hit - returning cached response",
      "level": 1,
      "auxiliary": {
          "requestId": {
              "value": options.request_id,
              "type": "string",
          },
          "cachedResponse": {
              "value": json.dumps(cached_response),
              "type": "object",
          },
      }
  })
  ```
</CodeGroup>