A Domain Logger Port: Decoupling From PSR-3 Without Losing Context

Book: Decoupled PHP — Clean and Hexagonal Architecture for Applications That Outlive the Framework Also by me: Thinking in Go (2-book series) — Complete Guide to Go Programming + Hexagonal Architecture in Go My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools Me: xgabriel.com | GitHub You open a use case that places an order. Near the top of the constructor, alongside the repositories and the payment gateway, sits a Psr\Log\LoggerInterface . The method body calls $this->logger->info(...) three times. It looks harmless. It is the most common way framework concerns leak back into a domain you spent weeks keeping clean. PSR-3 is a fine standard. Monolog is the default implementation in most PHP projects, and it earns that spot. The problem is not the library. The problem is where you point it. When LoggerInterface is a constructor argument in your application layer, your use case now depends on a package whose surface area you do not control, whose log levels you may not want, and whose context conventions are someone else's. The dependency arrow points the wrong way. What PSR-3 drags in Psr\Log\LoggerInterface is eight level methods plus a generic log() . The level taxonomy comes from RFC 5424 syslog: emergency , alert , critical , error , warning , notice , info , debug . That is a system-administration vocabulary. Your domain does not speak it. When a use case calls $this->logger->warning('payment retry') , you have to ask: is a retry a warning or a notice ? The answer is an infrastructure judgment call wearing a domain costume. The method signature also accepts an arbitrary array $context and a string|Stringable $message with {placeholder} interpolation. None of that is something your application code should be deciding. <?php declare ( strict_types = 1 ); namespace App\Application\Order ; use Psr\Log\LoggerInterface ; final readonly class PlaceOrder { public function __construct ( private OrderRepository $ord