From f36b4d5a6304ec91f18bd0a165ef5f8379d7e5dc Mon Sep 17 00:00:00 2001
From: pauldambra <paul@posthog.com>
Date: Fri, 16 Oct 2026 15:44:55 +0100
Subject: [PATCH] fix: resend complete batches on socket retries

Generated-By: PostHog Desktop
Task-Id: 5681be44-4986-48db-b140-1bda88f75f96
---
 .changeset/socket-retry-state.md |  5 +++++
 lib/Consumer/Socket.php          |  8 ++++++--
 sdk_compliance_adapter/README.md | 12 ++++++++----
 test/ConsumerSocketTest.php      | 30 ++++++++++++++++++++++++++++++
 4 files changed, 49 insertions(+), 6 deletions(-)
 create mode 100644 .changeset/socket-retry-state.md

diff --git a/.changeset/socket-retry-state.md b/.changeset/socket-retry-state.md
new file mode 100644
index 00000000..7bab3e01
--- /dev/null
+++ b/.changeset/socket-retry-state.md
@@ -0,0 +1,5 @@
+---
+"posthog-php": patch
+---
+
+Resend the complete batch when the Socket consumer retries a request.
diff --git a/lib/Consumer/Socket.php b/lib/Consumer/Socket.php
index 52cecb7c..f65970b7 100644
--- a/lib/Consumer/Socket.php
+++ b/lib/Consumer/Socket.php
@@ -113,14 +113,15 @@ private function createSocket()
      */
     private function makeRequest($socket, $req, $retry = true)
     {
-        $bytes_written = 0;
         $bytes_total = strlen($req);
-        $closed = false;
 
         // Retries with exponential backoff until success
         $backoff = 100;   // Set initial waiting time to 100ms
 
         while (true) {
+            $bytes_written = 0;
+            $closed = false;
+
             // Send request to server
             while (!$closed && $bytes_written < $bytes_total) {
                 try {
@@ -173,6 +174,9 @@ private function makeRequest($socket, $req, $retry = true)
             // Retry uploading...
             $backoff *= 2;
             $socket = $this->createSocket();
+            if (false === $socket) {
+                break;
+            }
         }
 
         return false;
diff --git a/sdk_compliance_adapter/README.md b/sdk_compliance_adapter/README.md
index 1c4e30b4..a5b2f1e8 100644
--- a/sdk_compliance_adapter/README.md
+++ b/sdk_compliance_adapter/README.md
@@ -68,8 +68,9 @@ not SDK shutdown certification; `/flush` always calls the real public SDK method
 
 ## Known failures and applicability
 
-LibCurl is expected to pass all 47 selected tests. Socket and foreground ForkCurl
-each expose these 11 existing capture failures:
+LibCurl is expected to pass all 47 selected tests. Foreground ForkCurl exposes
+these 11 capture failures. The last Socket report also contains these failures;
+it predates the Socket write-state repair:
 
 - `capture.retry_behavior.retries_on_503`
 - `capture.retry_behavior.retries_on_500`
@@ -83,8 +84,11 @@ each expose these 11 existing capture failures:
 - `capture.deduplication.preserves_uuid_and_timestamp_on_retry`
 - `capture.deduplication.preserves_uuid_and_timestamp_on_batch_retry`
 
-Socket does not reset its write state on retry, treats 408 as terminal, and ignores
-Retry-After. ForkCurl does not retry HTTP rejection and reports a successful curl
+Socket now resends the complete request on each attempt. Native regression tests
+cover 503 and 429 followed by 200, stable request bodies, and queue drain. The full
+Socket compliance suite was not rerun for that repair. Socket still treats 408 as
+terminal and ignores Retry-After. ForkCurl does not retry HTTP rejection and
+reports a successful curl
 process exit as successful delivery even for HTTP errors. The adapter exposes
 these behaviors rather than retrying on the SDK's behalf.
 
diff --git a/test/ConsumerSocketTest.php b/test/ConsumerSocketTest.php
index 38479cee..3fc29031 100644
--- a/test/ConsumerSocketTest.php
+++ b/test/ConsumerSocketTest.php
@@ -2,6 +2,7 @@
 
 namespace PostHog\Test;
 
+use PHPUnit\Framework\Attributes\DataProvider;
 use RuntimeException;
 
 class ConsumerSocketTest extends ConsumerTransportTestCase
@@ -11,6 +12,35 @@ protected function consumer(): string
         return 'socket';
     }
 
+    public static function retryableStatuses(): array
+    {
+        return ['server failure' => [503], 'rate limit' => [429]];
+    }
+
+    #[DataProvider('retryableStatuses')]
+    public function testRetrySendsTheCompleteBatch(int $status): void
+    {
+        $this->server->stop();
+        $this->server = new LocalHttpServer([['status' => $status], ['status' => 200]]);
+        $client = $this->client(['maximum_backoff_duration' => 200]);
+        $previousTimeout = ini_set('default_socket_timeout', '1');
+
+        try {
+            self::assertTrue($client->capture(['distinctId' => 'some-user', 'event' => 'retried event']));
+            self::assertTrue($client->flush());
+            $requests = $this->server->requests();
+            self::assertCount(2, $requests);
+            self::assertSame('POST /batch/ HTTP/1.1', $requests[1]['requestLine']);
+            self::assertSame($requests[0]['body'], $requests[1]['body']);
+            $payload = json_decode($requests[1]['body'], true, 512, JSON_THROW_ON_ERROR);
+            self::assertSame('retried event', $payload['batch'][0]['event']);
+            self::assertTrue($client->flush());
+            self::assertCount(2, $this->server->requests());
+        } finally {
+            ini_set('default_socket_timeout', $previousTimeout);
+        }
+    }
+
     public function testShortTimeout(): void
     {
         $client = $this->client(['timeout' => 0.01]);