fix(fork): fully isolate inherited Redis connections in the message child

The per-message fork child purged cache/redis manager singletons but never reset
the session bindings, and never actively disconnected the fds it inherited. Once an
app puts session + cache on Redis, the parent's authenticateConnection() opens Redis
sockets before forking; a child touching any un-reset connection interleaves on the
shared fd and desyncs the predis protocol on BOTH sides — flooding
"unserialize(): Error at offset 0 of N bytes" and
"Predis ConnectionException: Error while reading line from the server".

In the child, before purging: disconnect() every configured redis connection (closes
only the child's fd copy — predis disconnect fcloses without sending a command, so
the parent socket is untouched; any later reuse reconnects fresh instead of
desyncing), then also forgetInstance('session') + 'session.store' so a Redis-backed
session store rebuilds lazily too.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/Websocket/Handler.php

@@ -590,13 +590,44 @@ class Handler implements MessageComponentInterface
                 // This saves ~5-15ms for methods that don't use the database
                 DB::disconnect();
 
-                // Purge inherited Redis/cache connections from parent process.
-                // After fork(), child inherits parent's Redis socket fd — using it
-                // would corrupt parent's protocol state. Purging forces fresh
-                // connections on next cache() call (predis connects lazily).
+                // Purge inherited Redis/cache/session connections from the parent.
+                // After fork(), the child inherits the parent's Redis socket fds; using
+                // any of them interleaves requests on the shared socket and desyncs the
+                // predis protocol on BOTH the child AND the parent (unserialize "offset 0
+                // of N bytes" / "Error while reading line"). Once session + cache live on
+                // Redis, the parent's authenticateConnection() opens Redis fds before it
+                // forks, so the child must drop EVERY inherited connection.
+                //
+                // 1) Actively disconnect each configured connection — this closes ONLY the
+                //    child's fd copy (predis disconnect just fcloses, it sends no command,
+                //    so the parent's socket is untouched), turning any accidental later
+                //    reuse into a fresh reconnect instead of a desync.
+                try {
+                    $redisManager = app('redis');
+                    foreach (config('database.redis', []) as $redisName => $redisConf) {
+                        // Skip non-connection entries (client, options, clusters, …).
+                        if (! is_array($redisConf) || ! isset($redisConf['host'])) {
+                            continue;
+                        }
+                        try {
+                            $redisManager->connection($redisName)->disconnect();
+                        } catch (\Throwable $e) {
+                            // per-connection best-effort
+                        }
+                    }
+                } catch (\Throwable $e) {
+                    // best-effort; the forgetInstance() calls below still force fresh managers
+                }
+
+                // 2) Forget the singletons so the next cache()/session()/Redis() call
+                //    lazily rebuilds with a fresh socket. session/session.store were the
+                //    gap: once the session store is Redis-backed they hold their OWN
+                //    inherited Redis connection, which the cache/redis purge never reset.
                 app()->forgetInstance('cache');
                 app()->forgetInstance('cache.store');
                 app()->forgetInstance('redis');
+                app()->forgetInstance('session');
+                app()->forgetInstance('session.store');
 
                 // Configure DB reconnect-on-lost-connection for this child.
                 // If MySQL returns "Too many connections" or "server has gone away",