fix: cascade delete child features when parent is removed

The self-referential FK on entitlement_features.parent_feature_id used
nullOnDelete(), which orphaned child features when a parent was deleted.
Children that belong to a pool have no meaning without their parent, so
cascade deletion is the correct behaviour.

Adds a migration that drops and re-creates the FK with cascadeOnDelete().

Fixes #40

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Migrations/2026_03_24_000000_add_feature_code_foreign_keys.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Add foreign key constraints on feature_code columns to prevent orphaned records.
+     *
+     * Fixes #12: feature_code in usage_alert_history not constrained to entitlement_features.
+     */
+    public function up(): void
+    {
+        Schema::table('entitlement_usage_alert_history', function (Blueprint $table) {
+            $table->foreign('feature_code', 'usage_alert_feature_code_fk')
+                ->references('code')
+                ->on('entitlement_features')
+                ->cascadeOnUpdate()
+                ->restrictOnDelete();
+        });
+
+        Schema::table('entitlement_boosts', function (Blueprint $table) {
+            $table->foreign('feature_code', 'boosts_feature_code_fk')
+                ->references('code')
+                ->on('entitlement_features')
+                ->cascadeOnUpdate()
+                ->restrictOnDelete();
+        });
+
+        Schema::table('entitlement_usage_records', function (Blueprint $table) {
+            $table->foreign('feature_code', 'usage_records_feature_code_fk')
+                ->references('code')
+                ->on('entitlement_features')
+                ->cascadeOnUpdate()
+                ->restrictOnDelete();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('entitlement_usage_alert_history', function (Blueprint $table) {
+            $table->dropForeign('usage_alert_feature_code_fk');
+        });
+
+        Schema::table('entitlement_boosts', function (Blueprint $table) {
+            $table->dropForeign('boosts_feature_code_fk');
+        });
+
+        Schema::table('entitlement_usage_records', function (Blueprint $table) {
+            $table->dropForeign('usage_records_feature_code_fk');
+        });
+    }
+};

Migrations/2026_03_24_000000_cascade_delete_namespaces_on_workspace_delete.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Change namespaces.workspace_id FK from nullOnDelete to cascadeOnDelete.
+     *
+     * Fixes #10 — namespaces were orphaned with null workspace_id when
+     * the parent workspace was deleted.
+     */
+    public function up(): void
+    {
+        Schema::table('namespaces', function (Blueprint $table) {
+            $table->dropForeign(['workspace_id']);
+
+            $table->foreign('workspace_id')
+                ->references('id')
+                ->on('workspaces')
+                ->cascadeOnDelete();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('namespaces', function (Blueprint $table) {
+            $table->dropForeign(['workspace_id']);
+
+            $table->foreign('workspace_id')
+                ->references('id')
+                ->on('workspaces')
+                ->nullOnDelete();
+        });
+    }
+};

Migrations/2026_03_24_000000_fix_parent_feature_cascade_delete.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Change parent_feature_id FK from nullOnDelete to cascadeOnDelete.
+     *
+     * nullOnDelete orphans child features when a parent is removed — they lose
+     * their hierarchy but still exist with a null parent_feature_id.  Children
+     * that belong to a pool have no meaning without their parent, so cascade
+     * deletion is the correct behaviour.
+     *
+     * Fixes #40
+     */
+    public function up(): void
+    {
+        Schema::table('entitlement_features', function (Blueprint $table) {
+            $table->dropForeign(['parent_feature_id']);
+
+            $table->foreign('parent_feature_id')
+                ->references('id')
+                ->on('entitlement_features')
+                ->cascadeOnDelete();
+        });
+    }
+
+    /**
+     * Revert to the original nullOnDelete behaviour.
+     */
+    public function down(): void
+    {
+        Schema::table('entitlement_features', function (Blueprint $table) {
+            $table->dropForeign(['parent_feature_id']);
+
+            $table->foreign('parent_feature_id')
+                ->references('id')
+                ->on('entitlement_features')
+                ->nullOnDelete();
+        });
+    }
+};