improve serialization for workflow interrupt

Author: ilvalerione

src/MCP/McpConnector.php

@@ -44,16 +44,17 @@ class McpConnector
 
     /**
      * @param array<string, mixed> $config
-     * @throws McpException
      */
     public function __construct(protected array $config)
     {
-        $this->connectClient();
     }
 
-    protected function connectClient()
+    /**
+     * @throws McpException
+     */
+    protected function client(): MCPClient
     {
-        $this->client = new McpClient($this->config);
+        return $this->client ??= new McpClient($this->config);
     }
 
     public function __serialize(): array
@@ -70,8 +71,6 @@ public function __unserialize(array $data): void
         $this->config = $data['config'];
         $this->only = $data['only'];
         $this->exclude = $data['exclude'];
-
-        $this->connectClient();
     }
 
     /**
@@ -102,7 +101,7 @@ public function tools(): array
     {
         // Filter by the only and exclude preferences.
         $tools = array_filter(
-            $this->client->listTools(),
+            $this->client()->listTools(),
             fn (array $tool): bool =>
                 !in_array($tool['name'], $this->exclude) &&
                 ($this->only === [] || in_array($tool['name'], $this->only)),
@@ -202,11 +201,12 @@ protected function createObjectProperty(string $name, bool $required, array $pro
 
     /**
      * This might look counter-intuitive, but when dealing with interrupts and serialization PHP doesnt allow for MCP connectors serialization
+     * @throws McpException
      */
     public function invokeTool(array $item, array $arguments): mixed
     {
         $response = call_user_func(
-            $this->client->callTool(...),
+            $this->client()->callTool(...),
             $item['name'],
             $arguments
         );

src/Testing/FakeMcpTransport.php

@@ -45,9 +45,9 @@ public function __serialize(): array
         return [
             'queue' => [
                 ...$this->sent,
-                ...$this->responseQueue
+                ...$this->responseQueue,
             ],
-            'connected' => $this->connected
+            'connected' => $this->connected,
         ];
     }
 

src/Workflow/Persistence/DatabasePersistence.php

@@ -10,6 +10,7 @@
 
 use function serialize;
 use function unserialize;
+use function base64_decode;
 
 class DatabasePersistence implements PersistenceInterface
 {
@@ -33,17 +34,32 @@ public function save(string $workflowId, WorkflowInterrupt $interrupt): void
         ]);
     }
 
+    /**
+     * @throws WorkflowException
+     */
     public function load(string $workflowId): WorkflowInterrupt
     {
         $stmt = $this->pdo->prepare("SELECT interrupt FROM {$this->table} WHERE workflow_id = :id");
         $stmt->execute(['id' => $workflowId]);
-        $result = $stmt->fetch();
+        $record = $stmt->fetch();
 
-        if (!$result) {
+        if (!$record) {
             throw new WorkflowException("No saved workflow found for ID: {$workflowId}.");
         }
 
-        return unserialize($result['interrupt']);
+        $interruptData = @unserialize(
+            base64_decode((string) $record['interrupt'], true)
+        );
+
+        if ($interruptData === false) {
+            $interruptData = unserialize($record['interrupt']); // This makes sure that previous records still work
+        }
+
+        if ($interruptData === false) {
+            throw new WorkflowException("Failed to unserialize saved workflow for ID: {$workflowId}.");
+        }
+
+        return $interruptData;
     }
 
     public function delete(string $workflowId): void

src/Workflow/Persistence/EloquentPersistence.php

@@ -33,6 +33,9 @@ public function save(string $workflowId, WorkflowInterrupt $interrupt): void
         ]);
     }
 
+    /**
+     * @throws WorkflowException
+     */
     public function load(string $workflowId): WorkflowInterrupt
     {
         /** @var Model&object{interrupt: string} $model */

tests/MCP/McpConnectorTest.php

@@ -75,7 +75,6 @@ public function testCallableMcpToolsIsSerializable(): void
 
         // Test serialization
         $serialized = serialize($callable);
-        $this->assertIsString($serialized);
 
         // Test unserialization
         $unserialized = unserialize($serialized);
@@ -99,7 +98,7 @@ public function testInvokeToolStaticMethodCreatesNewInstance(): void
                         ['type' => 'text', 'text' => 'The result is 42'],
                     ],
                 ],
-            ]
+            ],
             ]);
 
 
@@ -136,7 +135,7 @@ public function testInvokeToolThrowsExceptionOnError(): void
                     'error' => [
                         'message' => 'Tool execution failed',
                     ],
-                ]
+                ],
             ]
         );
 
@@ -259,7 +258,7 @@ public function testFakeTransportToolCalling(): void
                         ['type' => 'text', 'text' => 'The result is 42'],
                     ],
                 ],
-            ]
+            ],
             ]
         );