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# Overview

Tracer is Quantum’s global error-handling layer.

Use it during bootstrap to convert PHP runtime errors into exceptions and send uncaught throwables through a consistent CLI or web response path.

## What it provides

* `ErrorHandler` for registration and runtime routing
* `ExceptionSeverityResolver` for logger severity selection
* `WebExceptionRenderer` for debug and production error views
* `StackTraceFormatter` for source snippets in debug trace pages

## Quick setup

```php
use Quantum\Tracer\ErrorHandler;

$handler = new ErrorHandler();
$handler->setup($logger);
```

## Runtime behavior

After setup:

* enabled PHP errors become `ErrorException` instances
* uncaught throwables are routed by runtime (`cli` or web)
* web requests return HTTP 500 for uncaught exceptions
* production web requests log the exception before rendering the response

## Debug and production output

* CLI debug: class, message, file/line, and full trace
* CLI production: exception message in the terminal output
* Web debug: `errors/trace` partial with formatted stack trace data
* Web production: `errors/500` partial

## Practical constraints

* Production logging happens in the web exception path.
* Uncaught web exceptions use a 500 response.
* Source snippets appear when the filesystem adapter can read local source files.


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