fix: restore signature adapter compatibility

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

src/Integration/SignatureAppearanceXObjectAdapter.php

@@ -0,0 +1,27 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreSign
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreSign\XObjectTemplate\Integration;
+
+use LibreSign\XObjectTemplate\Dto\CompileResult;
+
+final class SignatureAppearanceXObjectAdapter
+{
+    /**
+     * Output compatible with consumers expecting the historical PDF signer payload.
+     *
+     * @return array{
+     *     stream: string,
+     *     resources: array<string, mixed>,
+     *     bbox: array{0: float, 1: float, 2: float, 3: float}
+     * }
+     */
+    public function toPdfSignerPayload(CompileResult $result): array
+    {
+        return (new XObjectPayloadAdapter())->toXObjectPayload($result);
+    }
+}

tests/Unit/Integration/SignatureAppearanceXObjectAdapterTest.php

@@ -0,0 +1,31 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreSign
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreSign\XObjectTemplate\Tests\Unit\Integration;
+
+use LibreSign\XObjectTemplate\Dto\CompileResult;
+use LibreSign\XObjectTemplate\Integration\SignatureAppearanceXObjectAdapter;
+use PHPUnit\Framework\TestCase;
+
+final class SignatureAppearanceXObjectAdapterTest extends TestCase
+{
+    public function testAdapterMapsToExpectedPayload(): void
+    {
+        $adapter = new SignatureAppearanceXObjectAdapter();
+        $result = new CompileResult(
+            contentStream: 'BT\n(Foo) Tj\nET',
+            resources: ['Font' => ['F1' => ['BaseFont' => '/Helvetica']]],
+            bbox: [0.0, 0.0, 240.0, 84.0],
+        );
+
+        $payload = $adapter->toPdfSignerPayload($result);
+
+        self::assertSame('BT\n(Foo) Tj\nET', $payload['stream']);
+        self::assertSame(['Font' => ['F1' => ['BaseFont' => '/Helvetica']]], $payload['resources']);
+        self::assertSame([0.0, 0.0, 240.0, 84.0], $payload['bbox']);
+    }
+}