diff --git a/AGENTS.md b/AGENTS.md
index b26494221..ffa31d4fe 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -12,6 +12,7 @@ This file provides guidance to AI agents when working with code in this reposito
     - Prioritize backward compatibility and type safety in all code changes.
     - Ensure comprehensive test coverage for any new or modified code.
     - Keep the `CHANGELOG.md` file updated with all significant changes.
+    - **MANDATORY**: Run `make fix-phpcs` before each commit to ensure code follows PSR-2 standards.
 
 ## Tools
 
@@ -52,6 +53,13 @@ This file provides guidance to AI agents when working with code in this reposito
 - **Fixing coding standards**: `make fix-phpcs`
 - **Running static analysis**: `make run-phpstan`
 
+### Commit Workflow
+
+- **Before each commit**: ALWAYS run `make fix-phpcs` to ensure code follows PSR-2 standards
+- **After fixing**: Run `make run-phpcs` to verify no issues remain
+- **Test before commit**: Run relevant tests to ensure functionality works
+- **Update CHANGELOG**: Add entries for significant changes (except test-only changes)
+
 ## Knowledge
 
 ### Project Overview
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9649f760a..6f96ddfb4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Added support for Component Template [#2274](https://github.com/ruflin/Elastica/pull/2274)
 * Added support for Index Template  [#2274](https://github.com/ruflin/Elastica/pull/2274)
 * Added Template class to target only legacy Template [#2274](https://github.com/ruflin/Elastica/pull/2274)
+* Added support for `seq_no_primary_term` search option to retrieve sequence numbers and primary terms in search results
+* Added support for `if_seq_no` and `if_primary_term` options in `Index::addDocument()` for optimistic concurrency control
 ### Changed
 ### Deprecated
 ### Removed
diff --git a/src/Index.php b/src/Index.php
index 169f43d49..62e409b37 100644
--- a/src/Index.php
+++ b/src/Index.php
@@ -207,6 +207,8 @@ public function addDocument(Document $doc): Response
         $options = $doc->getOptions(
             [
                 'consistency',
+                'if_seq_no',
+                'if_primary_term',
                 'op_type',
                 'parent',
                 'percolate',
diff --git a/src/Search.php b/src/Search.php
index 7b1b288e3..e5ef0fcfd 100644
--- a/src/Search.php
+++ b/src/Search.php
@@ -41,6 +41,7 @@ class Search
     public const OPTION_SHARD_REQUEST_CACHE = 'request_cache';
     public const OPTION_FILTER_PATH = 'filter_path';
     public const OPTION_TYPED_KEYS = 'typed_keys';
+    public const OPTION_SEQ_NO_PRIMARY_TERM = 'seq_no_primary_term';
 
     /*
      * Search types
@@ -413,6 +414,7 @@ protected function validateOption(string $key): void
             case self::OPTION_SHARD_REQUEST_CACHE:
             case self::OPTION_FILTER_PATH:
             case self::OPTION_TYPED_KEYS:
+            case self::OPTION_SEQ_NO_PRIMARY_TERM:
                 return;
         }
 
diff --git a/tests/IndexSeqNoPrimaryTermTest.php b/tests/IndexSeqNoPrimaryTermTest.php
new file mode 100644
index 000000000..1a5c22560
--- /dev/null
+++ b/tests/IndexSeqNoPrimaryTermTest.php
@@ -0,0 +1,117 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Elastica\Test;
+
+use Elastica\Document;
+use Elastica\Index;
+use Elastica\Test\Base as BaseTest;
+
+/**
+ * @group functional
+ *
+ * @internal
+ */
+class IndexSeqNoPrimaryTermTest extends BaseTest
+{
+    private Index $index;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->index = $this->_createIndex();
+    }
+
+    protected function tearDown(): void
+    {
+        $this->index->delete();
+        parent::tearDown();
+    }
+
+    /**
+     * @covers \Elastica\AbstractUpdateAction::setPrimaryTerm
+     * @covers \Elastica\AbstractUpdateAction::setSequenceNumber
+     * @covers \Elastica\Index::addDocument
+     *
+     * @group functional
+     */
+    public function testAddDocumentWithSeqNoPrimaryTerm(): void
+    {
+        $doc = new Document('1', ['title' => 'Test document']);
+        $doc->setSequenceNumber(1);
+        $doc->setPrimaryTerm(1);
+
+        $response = $this->index->addDocument($doc);
+
+        $this->assertTrue($response->isOk());
+    }
+
+    /**
+     * @covers \Elastica\AbstractUpdateAction::setPrimaryTerm
+     * @covers \Elastica\AbstractUpdateAction::setSequenceNumber
+     * @covers \Elastica\Index::addDocument
+     *
+     * @group functional
+     */
+    public function testAddDocumentWithOptimisticConcurrencyControl(): void
+    {
+        // First, add a document
+        $doc1 = new Document('1', ['title' => 'Original document']);
+        $response1 = $this->index->addDocument($doc1);
+        $this->assertTrue($response1->isOk());
+
+        // Get the document to retrieve its sequence number and primary term
+        $retrievedDoc = $this->index->getDocument('1');
+        $this->assertTrue($retrievedDoc->hasSequenceNumber());
+        $this->assertTrue($retrievedDoc->hasPrimaryTerm());
+
+        // Update the document using the retrieved sequence number and primary term
+        $doc2 = new Document('1', ['title' => 'Updated document']);
+        $doc2->setSequenceNumber($retrievedDoc->getSequenceNumber());
+        $doc2->setPrimaryTerm($retrievedDoc->getPrimaryTerm());
+
+        $response2 = $this->index->addDocument($doc2);
+        $this->assertTrue($response2->isOk());
+
+        // Verify the document was updated
+        $updatedDoc = $this->index->getDocument('1');
+        $this->assertEquals('Updated document', $updatedDoc->get('title'));
+    }
+
+    /**
+     * @covers \Elastica\AbstractUpdateAction::setPrimaryTerm
+     * @covers \Elastica\AbstractUpdateAction::setSequenceNumber
+     * @covers \Elastica\Index::addDocument
+     *
+     * @group functional
+     */
+    public function testAddDocumentWithStaleSeqNoPrimaryTerm(): void
+    {
+        // First, add a document
+        $doc1 = new Document('1', ['title' => 'Original document']);
+        $response1 = $this->index->addDocument($doc1);
+        $this->assertTrue($response1->isOk());
+
+        // Get the document to retrieve its sequence number and primary term
+        $retrievedDoc = $this->index->getDocument('1');
+        $originalSeqNo = $retrievedDoc->getSequenceNumber();
+        $originalPrimaryTerm = $retrievedDoc->getPrimaryTerm();
+
+        // Update the document once to change the sequence number
+        $doc2 = new Document('1', ['title' => 'First update']);
+        $doc2->setSequenceNumber($originalSeqNo);
+        $doc2->setPrimaryTerm($originalPrimaryTerm);
+        $response2 = $this->index->addDocument($doc2);
+        $this->assertTrue($response2->isOk());
+
+        // Try to update with the old sequence number and primary term (should fail)
+        $doc3 = new Document('1', ['title' => 'Second update']);
+        $doc3->setSequenceNumber($originalSeqNo);
+        $doc3->setPrimaryTerm($originalPrimaryTerm);
+
+        $response3 = $this->index->addDocument($doc3);
+        $this->assertFalse($response3->isOk());
+    }
+}
diff --git a/tests/SearchSeqNoPrimaryTermTest.php b/tests/SearchSeqNoPrimaryTermTest.php
new file mode 100644
index 000000000..761b2a387
--- /dev/null
+++ b/tests/SearchSeqNoPrimaryTermTest.php
@@ -0,0 +1,97 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Elastica\Test;
+
+use Elastica\Client;
+use Elastica\Document;
+use Elastica\Index;
+use Elastica\Search;
+use Elastica\Test\Base as BaseTest;
+
+/**
+ * @group functional
+ *
+ * @internal
+ */
+class SearchSeqNoPrimaryTermTest extends BaseTest
+{
+    private Index $index;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->index = $this->_createIndex();
+        $this->index->addDocument(new Document('1', ['title' => 'Test document']));
+        $this->index->refresh();
+    }
+
+    protected function tearDown(): void
+    {
+        $this->index->delete();
+        parent::tearDown();
+    }
+
+    /**
+     * @covers \Elastica\Search::setOption
+     *
+     * @group unit
+     */
+    public function testSetSeqNoPrimaryTermOption(): void
+    {
+        $client = $this->createMock(Client::class);
+        $search = new Search($client);
+
+        $search->setOption(Search::OPTION_SEQ_NO_PRIMARY_TERM, true);
+
+        $this->assertTrue($search->hasOption(Search::OPTION_SEQ_NO_PRIMARY_TERM));
+        $this->assertTrue($search->getOption(Search::OPTION_SEQ_NO_PRIMARY_TERM));
+    }
+
+    /**
+     * @covers \Elastica\Search::search
+     *
+     * @group functional
+     */
+    public function testSearchWithSeqNoPrimaryTerm(): void
+    {
+        $search = new Search($this->_getClient());
+        $search->addIndex($this->index);
+        $search->setOption(Search::OPTION_SEQ_NO_PRIMARY_TERM, true);
+
+        $resultSet = $search->search();
+
+        $this->assertGreaterThan(0, $resultSet->count());
+
+        foreach ($resultSet as $result) {
+            $this->assertArrayHasKey('_seq_no', $result->getHit());
+            $this->assertArrayHasKey('_primary_term', $result->getHit());
+            $this->assertIsInt($result->getHit()['_seq_no']);
+            $this->assertIsInt($result->getHit()['_primary_term']);
+        }
+    }
+
+    /**
+     * @covers \Elastica\Search::setOptionsAndQuery
+     *
+     * @group unit
+     */
+    public function testSetOptionsAndQueryWithSeqNoPrimaryTerm(): void
+    {
+        $client = $this->createMock(Client::class);
+        $search = new Search($client);
+
+        $options = [
+            Search::OPTION_SEQ_NO_PRIMARY_TERM => true,
+            Search::OPTION_SIZE => 10,
+        ];
+
+        $search->setOptionsAndQuery($options);
+
+        $this->assertTrue($search->hasOption(Search::OPTION_SEQ_NO_PRIMARY_TERM));
+        $this->assertTrue($search->getOption(Search::OPTION_SEQ_NO_PRIMARY_TERM));
+        $this->assertEquals(10, $search->getOption(Search::OPTION_SIZE));
+    }
+}