Debugging and Profiling

withDebug() enables request diagnostics on a handler. A boolean enables the default debug configuration; an options array configures available diagnostics. Responses can expose request-specific debug information through getDebugInfo().

$handler = fetch_client()->getHandler()->withDebug();
$response = $handler->get('https://api.example.test/health');
$debug = $response->getDebugInfo();

Debug details depend on the request path and configured options. Streaming and asynchronous execution follow different paths from the buffered synchronous request pipeline, so verify what metadata is populated for the operation being inspected.

Treat diagnostics as sensitive. Avoid logging authorization headers, cookies, credentials, request bodies, or full user-supplied URLs. Redact data before forwarding it to logs or tracing systems.