feat: guide tool and server instructions

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

src/Guides/GuideRepository.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Guides;
+
+/**
+ * Reads guide markdown files from one directory. Topic names are restricted to
+ * lowercase slugs, so no path outside the directory can ever be read.
+ */
+final class GuideRepository
+{
+    private const TOPIC_PATTERN = '/^[a-z0-9]+(?:-[a-z0-9]+)*$/';
+
+    public function __construct(private string $directory)
+    {
+    }
+
+    /** @return list<string> */
+    public function topics(): array
+    {
+        $files = glob($this->directory . '/*.md');
+        if ($files === false) {
+            return [];
+        }
+
+        $topics = [];
+        foreach ($files as $file) {
+            $topic = basename($file, '.md');
+            if (preg_match(self::TOPIC_PATTERN, $topic) === 1) {
+                $topics[] = $topic;
+            }
+        }
+        sort($topics);
+
+        return $topics;
+    }
+
+    public function get(string $topic): ?string
+    {
+        if (preg_match(self::TOPIC_PATTERN, $topic) !== 1 || ! in_array($topic, $this->topics(), true)) {
+            return null;
+        }
+
+        $path = $this->directory . '/' . $topic . '.md';
+        // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
+        $content = file_get_contents($path);
+
+        return $content === false ? null : $content;
+    }
+}

src/Guides/InstructionsBuilder.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Guides;
+
+use LIT\MCP\Integrations\Integration;
+use LIT\MCP\Integrations\IntegrationRegistry;
+
+/**
+ * Builds the short server instructions every MCP client loads on connect.
+ * Keep this text short: it occupies context in every conversation.
+ */
+final class InstructionsBuilder
+{
+    public function __construct(private IntegrationRegistry $registry)
+    {
+    }
+
+    public function build(): string
+    {
+        $active = implode(', ', array_map(
+            static fn (Integration $integration): string => $integration->id(),
+            $this->registry->available()
+        ));
+
+        return implode("\n", [
+            'LIT MCP pflegt diese WordPress-Website (Inhalte, Medien, Divi 5, Pods).',
+            'Aktive Integrationen: ' . $active . '.',
+            'Regeln:',
+            '- Vor dem ersten Arbeitsschritt lit-guide (ohne Topic) aufrufen; Details je Thema über lit-guide '
+                . 'mit topic.',
+            '- Änderungen erzeugen native Divi-Module; Variablen und Presets vor festen Werten; Code-Modul nur, '
+                . 'wenn kein natives Modul passt.',
+            '- Den Status (Entwurf/veröffentlicht) nie ändern, außer der Nutzer verlangt es ausdrücklich.',
+            '- Schreib-Tools verlangen den aktuellen rev-Wert aus dem letzten Lesevorgang.',
+            '- Fehler enthalten einen hint – ihm folgen, statt blind zu wiederholen.',
+        ]);
+    }
+}