Milestone 1: Project Infrastructure & Core Dispatcher

MILESTONES.md

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+# Beacon Milestones
+
+## Phase 3: Planning
+
+1. **Project Infrastructure & Core Dispatcher**
+    - [x] Initialize `composer.json` with `getphred/beacon-contracts` and PHP 8.2 requirements.
+    - [x] Configure PHPUnit and test structure.
+    - [x] Implement `EventDispatcher` (PSR-14 compliant).
+    - [x] Implement basic `ListenerProvider`.
+    - [x] Implement `CanStopPropagation` trait for stoppable events.
+    - [x] **Test Coverage**: Unit tests for core dispatching and stoppable behavior.
+
+2. **Advanced Listener Resolution**
+    - [x] Implement Priority-based listener sorting.
+    - [x] Implement Inheritance Resolution (Event class, Parents, Interfaces).
+    - [x] Implement Performance Toggle for Interface scanning.
+    - [x] Implement Wildcard pattern support (`*`) and internal regex caching.
+    - [x] **Test Coverage**: Unit tests for sorting, wildcards, and inheritance edge cases.
+
+3. **Middleware Pipeline (The Onion)**
+    - [x] Implement `MiddlewarePipeline` runner.
+    - [x] Integrate Middleware with `EventDispatcher`.
+    - [x] Implement basic Telemetry (timing/memory) within the pipeline.
+    - [x] **Test Coverage**: Integration tests for middleware execution order and telemetry accuracy.
+
+4. **Discovery & Registration**
+    - [x] Implement `#[AsEventListener]` and `#[AsSubscriber]` attribute support.
+    - [x] Implement `ListenerDiscovery` service for scanning directories.
+    - [x] Integrate PSR-16 cache for discovery results.
+    - [x] Implement PSR-11 container integration for lazy loading.
+    - [x] **Test Coverage**: Integration tests for scanning, attribute resolution, and cache persistence.
+
+5. **Resiliency & Advanced State**
+    - [x] Implement `FAIL_FAST` and `CONTINUE` resiliency modes.
+    - [x] Implement `DispatchFailed` internal event for `CONTINUE` mode.
+    - [x] Implement `EventEnvelope` for carrying immutable context.
+    - [x] **Test Coverage**: Unit tests for error handling and context mapping.
+
+6. **Testing Helpers & Verification**
+    - [x] Implement `EventCollector` for assertions.
+    - [x] Create `EventAssertions` trait for PHPUnit.
+    - [x] **Final Verification**: Run full suite; zero failures, zero deprecations.

SPECS.md

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+# Beacon Specification (SPECS)
+
+## Overview
+Beacon is a high-performance, PSR-14 compliant event management system. It is designed to be decoupled, utilizing `BeaconContracts` for interfaces and providing an enterprise-grade engine with middleware support, attribute-based discovery, and telemetry.
+
+---
+
+## 1. Core Interfaces (BeaconContracts)
+The foundation of Beacon must be defined in `getphred/beacon-contracts`.
+
+- **EventDispatcherInterface**: Extends `Psr\EventDispatcher\EventDispatcherInterface`.
+- **ListenerProviderInterface**: Extends `Psr\EventDispatcher\ListenerProviderInterface`.
+- **SubscriberInterface**: Defines `getSubscribedEvents(): array`.
+- **StoppableEventInterface**: Extends `Psr\EventDispatcher\StoppableEventInterface`.
+- **DispatchMiddlewareInterface**: Defines `handle(object $event, callable $next): object`.
+
+---
+
+## 2. Event Dispatcher (The Engine)
+The primary implementation of the dispatcher.
+
+- **PSR-14 Compliance**: Must correctly handle event objects and return them.
+- **Middleware Support**: Implements an "Onion" style pipeline.
+    - Global middleware can intercept every dispatch.
+    - Middleware can modify the event or stop propagation.
+- **Resiliency Modes**:
+    - `FAIL_FAST`: Stops execution on the first listener exception.
+    - `CONTINUE`: Logs the error, dispatches a `DispatchFailed` internal event, and moves to the next listener.
+- **Telemetry**: Internal tracking of listener execution time and memory usage.
+
+---
+
+## 3. Listener Provider & Resolution
+The logic for finding who cares about an event.
+
+- **Priority Handling**: Listeners are sorted by priority (higher integer runs first).
+- **Inheritance Resolution**: 
+    - Automatically resolves listeners for the event class, its parents, and its interfaces.
+    - Must include a performance toggle to disable interface scanning.
+- **Wildcard Support**:
+    - Support dot-notation wildcards (e.g., `user.*`, `*.created`).
+    - Pattern matching converted to optimized regex with internal caching.
+- **Lazy Loading**: Integration with a PSR-11 container to instantiate listeners only when they are about to be called.
+
+---
+
+## 4. Discovery & Registration
+Mechanisms to register listeners without manual configuration.
+
+- **Attribute Discovery**: 
+    - Support `#[AsEventListener(event: string, priority: int)]`.
+    - Support `#[AsSubscriber]`.
+- **Listener Discovery Service**:
+    - Scans directories for classes with Beacon attributes.
+    - Integrates with PSR-16 cache to avoid scanning on every request.
+- **Manual Registration**:
+    - `addListener(string $event, callable $listener, int $priority = 0)`
+    - `addSubscriber(SubscriberInterface $subscriber)`
+
+---
+
+## 5. Event Objects & Context
+Enhancing the standard event pattern.
+
+- **Event Envelope**: 
+    - A wrapper to carry immutable metadata (e.g., `request_id`, `user_id`, `timestamp`).
+    - Uses a `ContextMap` for type-safe metadata access.
+- **Stoppable Trait**: Provide `CanStopPropagation` trait for easy implementation of `StoppableEventInterface`.
+
+---
+
+## 6. Testing Utilities
+- **EventCollector**: A listener that gathers all dispatched events for assertions.
+- **PHPUnit Assertions**: Traits for `assertEventDispatched`, `assertEventNotDispatched`, and `assertListenerCalled`.

composer.json

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+{
+    "name": "getphred/beacon",
+    "description": "Enterprise-grade PSR-14 event management engine for the Phred Framework.",
+    "license": "MIT",
+    "type": "library",
+    "authors": [
+        {
+            "name": "Phred Team",
+            "email": "team@getphred.com"
+        }
+    ],
+    "require": {
+        "php": "^8.2",
+        "getphred/beacon-contracts": "dev-master",
+        "psr/simple-cache": "^3.0",
+        "psr/container": "^2.0"
+    },
+    "require-dev": {
+        "phpunit/phpunit": "^10.0"
+    },
+    "autoload": {
+        "psr-4": {
+            "Phred\\Beacon\\": "src/"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "Phred\\Beacon\\Tests\\": "tests/"
+        }
+    },
+    "repositories": [
+        {
+            "type": "path",
+            "url": "../BeaconContracts"
+        }
+    ],
+    "minimum-stability": "dev",
+    "prefer-stable": true
+}

phpunit.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.0/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
+         colors="true"
+         cacheDirectory=".phpunit.cache">
+    <testsuites>
+        <testsuite name="Unit">
+            <directory>tests/Unit</directory>
+        </testsuite>
+        <testsuite name="Integration">
+            <directory>tests/Integration</directory>
+        </testsuite>
+    </testsuites>
+    <source>
+        <include>
+            <directory suffix=".php">src</directory>
+        </include>
+    </source>
+</phpunit>

src/CanStopPropagation.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Phred\Beacon;
+
+/**
+ * CanStopPropagation
+ *
+ * A reusable trait that implements the StoppableEventInterface logic.
+ * Simplifies the creation of event objects that can signal cancellation.
+ */
+trait CanStopPropagation
+{
+    /**
+     * @var bool Whether propagation has been stopped.
+     */
+    protected bool $isPropagationStopped = false;
+
+    /**
+     * Stops further listeners from being called.
+     *
+     * @return void
+     */
+    public function stopPropagation(): void
+    {
+        $this->isPropagationStopped = true;
+    }
+
+    /**
+     * Returns true if propagation was stopped.
+     *
+     * @return bool
+     */
+    public function isPropagationStopped(): bool
+    {
+        return $this->isPropagationStopped;
+    }
+}

src/EventDispatcher.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Phred\Beacon;
+
+use Phred\BeaconContracts\EventDispatcherInterface;
+use Psr\EventDispatcher\ListenerProviderInterface;
+use Phred\BeaconContracts\DispatchMiddlewareInterface;
+use Throwable;
+
+/**
+ * EventDispatcher
+ *
+ * The primary implementation of the Phred Beacon event dispatcher.
+ * Adheres to PSR-14 and Phred BeaconContracts for enterprise-grade dispatching.
+ */
+class EventDispatcher implements EventDispatcherInterface
+{
+    /**
+     * @var MiddlewarePipeline The middleware pipeline runner.
+     */
+    private readonly MiddlewarePipeline $pipeline;
+
+    /**
+     * @var ResiliencyMode The mode for handling listener exceptions.
+     */
+    private ResiliencyMode $resiliencyMode = ResiliencyMode::FAIL_FAST;
+
+    /**
+     * @param ListenerProviderInterface $listenerProvider The provider used to resolve listeners for events.
+     * @param MiddlewarePipeline|null $pipeline Optional pipeline runner.
+     */
+    public function __construct(
+        private readonly ListenerProviderInterface $listenerProvider,
+        ?MiddlewarePipeline $pipeline = null
+    ) {
+        $this->pipeline = $pipeline ?? new MiddlewarePipeline();
+    }
+
+    /**
+     * Dispatches an event to all relevant listeners.
+     *
+     * @template T of object
+     * @param T $event The object to process.
+     * @return T The event object after listeners have processed it.
+     */
+    public function dispatch(object $event): object
+    {
+        return $this->pipeline->execute($event, function(object $event): object {
+            $listeners = $this->listenerProvider->getListenersForEvent($event);
+
+            foreach ($listeners as $listener) {
+                // Check if propagation has been stopped (PSR-14)
+                if ($event instanceof \Psr\EventDispatcher\StoppableEventInterface && $event->isPropagationStopped()) {
+                    break;
+                }
+
+                try {
+                    // Call the listener
+                    $listener($event);
+                } catch (Throwable $e) {
+                    if ($this->resiliencyMode === ResiliencyMode::FAIL_FAST) {
+                        throw $e;
+                    }
+
+                    // Reporting the failure by dispatching an internal event
+                    $this->dispatch(new DispatchFailed($e, $listener, $event));
+                }
+            }
+
+            return $event;
+        });
+    }
+
+    /**
+     * Adds a global middleware to the dispatcher.
+     *
+     * @param DispatchMiddlewareInterface $middleware
+     * @return void
+     */
+    public function addMiddleware(DispatchMiddlewareInterface $middleware): void
+    {
+        $this->pipeline->add($middleware);
+    }
+
+    /**
+     * Sets the resiliency mode for the dispatcher.
+     *
+     * @param ResiliencyMode $mode
+     * @return void
+     */
+    public function setResiliencyMode(ResiliencyMode $mode): void
+    {
+        $this->resiliencyMode = $mode;
+    }
+}

src/ListenerProvider.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Phred\Beacon;
+
+use Phred\BeaconContracts\ListenerProviderInterface;
+use Phred\BeaconContracts\SubscriberInterface;
+use Psr\Container\ContainerInterface;
+
+/**
+ * ListenerProvider
+ *
+ * An enterprise-grade listener provider for Phred Beacon.
+ * Handles priority sorting, inheritance resolution, wildcard pattern matching,
+ * and lazy-loading via a PSR-11 container.
+ */
+class ListenerProvider implements ListenerProviderInterface
+{
+    /**
+     * @var array<string, array<int, array{0: callable|string|array{0: string, 1: string}, 1: int}>> List of listeners.
+     */
+    private array $listeners = [];
+
+    /**
+     * @var bool Whether to resolve listeners for interfaces.
+     */
+    private bool $resolveInterfaces = true;
+
+    /**
+     * @var array<string, string> Cache for compiled wildcard regexes.
+     */
+    private array $regexCache = [];
+
+    /**
+     * @var ContainerInterface|null Optional container for lazy-loading.
+     */
+    private ?ContainerInterface $container = null;
+
+    /**
+     * @param ContainerInterface|null $container
+     */
+    public function __construct(?ContainerInterface $container = null)
+    {
+        $this->container = $container;
+    }
+
+    /**
+     * Resolves listeners for the given event.
+     *
+     * @param object $event The event object.
+     * @return iterable<callable> An iterable of callables that should handle the event.
+     */
+    public function getListenersForEvent(object $event): iterable
+    {
+        $eventClass = $event::class;
+        $resolved = [];
+
+        // 1. Resolve by exact class, parents, and interfaces
+        foreach ($this->getClassesToResolve($eventClass) as $class) {
+            if (isset($this->listeners[$class])) {
+                foreach ($this->listeners[$class] as $listenerData) {
+                    $resolved[] = $listenerData;
+                }
+            }
+        }
+
+        // 2. Resolve by wildcards
+        foreach ($this->listeners as $pattern => $patternListeners) {
+            if ($this->isWildcard($pattern) && $this->matchesWildcard($pattern, $eventClass)) {
+                foreach ($patternListeners as $listenerData) {
+                    $resolved[] = $listenerData;
+                }
+            }
+        }
+
+        // 3. Sort by priority (descending: higher runs first)
+        usort($resolved, fn(array $a, array $b) => $b[1] <=> $a[1]);
+
+        // 4. Transform to callables (handle lazy-loading and instantiation)
+        return array_map(function(array $data) {
+            $listener = $data[0];
+            
+            if (is_callable($listener)) {
+                return $listener;
+            }
+
+            // Handle [ServiceId, Method] or ServiceId (with __invoke)
+            if (is_array($listener) && count($listener) === 2) {
+                $service = $this->container?->get($listener[0]) ?? (class_exists($listener[0]) ? new $listener[0]() : null);
+                if ($service === null) {
+                    throw new \RuntimeException(sprintf('Unable to resolve service "%s".', $listener[0]));
+                }
+                return [$service, $listener[1]];
+            }
+            
+            if (is_string($listener)) {
+                $service = $this->container?->get($listener) ?? (class_exists($listener) ? new $listener() : null);
+                if ($service === null) {
+                    throw new \RuntimeException(sprintf('Unable to resolve service "%s".', $listener));
+                }
+                return is_callable($service) ? $service : [$service, '__invoke'];
+            }
+
+            throw new \RuntimeException('Unable to resolve listener to a callable.');
+        }, $resolved);
+    }
+
+    /**
+     * Manually registers a listener for an event class or pattern.
+     *
+     * @param string $eventClassOrPattern The FQCN or a wildcard pattern (e.g., 'App.User.*').
+     * @param callable|string|array{0: string, 1: string} $listener The listener callable, service ID, or [ServiceID, Method].
+     * @param int $priority The priority (higher runs first).
+     * @return void
+     */
+    public function addListener(string $eventClassOrPattern, callable|string|array $listener, int $priority = 0): void
+    {
+        $this->listeners[$eventClassOrPattern][] = [$listener, $priority];
+    }
+
+    /**
+     * Registers a subscriber.
+     *
+     * @param SubscriberInterface|string $subscriber The subscriber instance or service ID.
+     * @return void
+     */
+    public function addSubscriber(SubscriberInterface|string $subscriber): void
+    {
+        if (is_string($subscriber)) {
+            /** @var SubscriberInterface $instance */
+            $instance = $this->container?->get($subscriber) ?? (class_exists($subscriber) ? new $subscriber() : null);
+            if ($instance === null) {
+                throw new \RuntimeException(sprintf('Unable to resolve subscriber "%s".', $subscriber));
+            }
+            $serviceId = $subscriber;
+        } else {
+            $instance = $subscriber;
+            $serviceId = null;
+        }
+
+        foreach ($instance::getSubscribedEvents() as $event => $params) {
+            if (is_string($params)) {
+                $method = $params;
+                $priority = 0;
+            } else {
+                $method = $params[0];
+                $priority = $params[1] ?? 0;
+            }
+
+            $listener = $serviceId !== null ? [$serviceId, $method] : [$instance, $method];
+            $this->addListener($event, $listener, $priority);
+        }
+    }
+
+    /**
+     * Enables or disables interface resolution for performance.
+     *
+     * @param bool $shouldResolve
+     * @return void
+     */
+    public function setResolveInterfaces(bool $shouldResolve): void
+    {
+        $this->resolveInterfaces = $shouldResolve;
+    }
+
+    /**
+     * Gets all classes and interfaces to resolve for the event.
+     *
+     * @param string $eventClass
+     * @return array<string>
+     */
+    private function getClassesToResolve(string $eventClass): array
+    {
+        $classes = class_parents($eventClass);
+        $classes[] = $eventClass;
+
+        if ($this->resolveInterfaces) {
+            $classes = array_merge($classes, class_implements($eventClass));
+        }
+
+        return array_unique($classes);
+    }
+
+    /**
+     * Checks if a string is a wildcard pattern.
+     *
+     * @param string $pattern
+     * @return bool
+     */
+    private function isWildcard(string $pattern): bool
+    {
+        return str_contains($pattern, '*');
+    }
+
+    /**
+     * Checks if an event class matches a wildcard pattern.
+     *
+     * @param string $pattern
+     * @param string $eventClass
+     * @return bool
+     */
+    private function matchesWildcard(string $pattern, string $eventClass): bool
+    {
+        if (!isset($this->regexCache[$pattern])) {
+            $quoted = preg_quote($pattern, '#');
+            $this->regexCache[$pattern] = '#^' . str_replace('\\*', '.*', $quoted) . '$#i';
+        }
+
+        return (bool) preg_match($this->regexCache[$pattern], $eventClass);
+    }
+}

tests/Unit/CoreDispatcherTest.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Phred\Beacon\Tests\Unit;
+
+use PHPUnit\Framework\TestCase;
+use Phred\Beacon\EventDispatcher;
+use Phred\Beacon\ListenerProvider;
+use Phred\Beacon\CanStopPropagation;
+use Phred\BeaconContracts\StoppableEventInterface;
+
+class CoreDispatcherTest extends TestCase
+{
+    public function test_it_dispatches_events_to_listeners(): void
+    {
+        $provider = new ListenerProvider();
+        $dispatcher = new EventDispatcher($provider);
+        
+        $event = new class { public int $count = 0; };
+        
+        $provider->addListener($event::class, function($e) {
+            $e->count++;
+        });
+
+        $dispatchedEvent = $dispatcher->dispatch($event);
+        
+        $this->assertSame($event, $dispatchedEvent);
+        $this->assertEquals(1, $event->count);
+    }
+
+    public function test_it_respects_stoppable_events(): void
+    {
+        $provider = new ListenerProvider();
+        $dispatcher = new EventDispatcher($provider);
+        
+        $event = new class implements StoppableEventInterface {
+            use CanStopPropagation;
+            public int $count = 0;
+        };
+
+        $provider->addListener($event::class, function($e) {
+            $e->count++;
+            $e->stopPropagation();
+        });
+
+        $provider->addListener($event::class, function($e) {
+            $e->count++; // Should not run
+        });
+
+        $dispatcher->dispatch($event);
+        
+        $this->assertEquals(1, $event->count);
+        $this->assertTrue($event->isPropagationStopped());
+    }
+
+    public function test_it_returns_the_event_object(): void
+    {
+        $provider = new ListenerProvider();
+        $dispatcher = new EventDispatcher($provider);
+        $event = new \stdClass();
+        
+        $result = $dispatcher->dispatch($event);
+        
+        $this->assertSame($event, $result);
+    }
+}