added media, mutation events, agent instructions

app/Policies/MutationPolicy.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace App\Policies;
+
+use App\Models\Mutation;
+use App\Models\User;
+
+class MutationPolicy
+{
+    /**
+     * Determine whether the user can view the mutation.
+     */
+    public function view(User $user, Mutation $mutation): bool
+    {
+        $dynamic = $mutation->ledger->dynamic;
+
+        return $dynamic->participants()->where('user_id', $user->id)->exists();
+    }
+}