Add SyncExecutor to server

.gitignore

@@ -19,3 +19,7 @@ __pycache__
 
 # misc
 .vscode
+.mcp.json
+.claude
+CLAUDE.md
+.kli/**

lightbug_http/server.mojo

@@ -472,6 +472,60 @@ fn handle_connection[
             break
 
 
+struct SyncExecutor[T: HTTPService](Movable):
+    """Single-threaded executor: handles each connection to completion before accepting the next.
+
+    This is the default executor used by `Server.serve`. It processes connections
+    sequentially — receive, parse, dispatch to handler, respond — then loops back
+    to accept the next connection.
+
+    Parameters:
+        T: The HTTP service type that handles incoming requests.
+    """
+
+    var provision_pool: ProvisionPool
+    var config: ServerConfig
+    var server_address: String
+    var tcp_keep_alive: Bool
+
+    fn __init__(out self, config: ServerConfig, server_address: String, tcp_keep_alive: Bool):
+        self.provision_pool = ProvisionPool(config.max_connections, config)
+        self.config = config.copy()
+        self.server_address = server_address
+        self.tcp_keep_alive = tcp_keep_alive
+
+    fn execute(mut self, var conn: TCPConnection[NetworkType.tcp4], mut handler: Self.T):
+        var index: Int
+        try:
+            index = self.provision_pool.borrow()
+        except:
+            try:
+                conn^.teardown()
+            except:
+                pass
+            return
+
+        try:
+            handle_connection(
+                conn,
+                self.provision_pool.provisions[index],
+                handler,
+                self.config,
+                self.server_address,
+                self.tcp_keep_alive,
+            )
+        except:
+            pass
+        finally:
+            try:
+                conn^.teardown()
+            except:
+                pass
+            self.provision_pool.provisions[index].prepare_for_new_request()
+            self.provision_pool.provisions[index].keepalive_count = 0
+            self.provision_pool.release(index)
+
+
 struct Server(Movable):
     """HTTP/1.1 Server implementation."""
 
@@ -543,7 +597,7 @@ struct Server(Movable):
             raise server_err^
 
     fn serve[T: HTTPService](self, ln: NoTLSListener[NetworkType.tcp4], mut handler: T) raises ServerError:
-        """Serve HTTP requests from an existing listener.
+        """Serve HTTP requests from an existing listener using the default single-threaded executor.
 
         Parameters:
             T: The type of HTTPService that handles incoming requests.
@@ -555,46 +609,34 @@ struct Server(Movable):
         Raises:
             ServerError: If accept fails or critical connection handling errors occur.
         """
-        var provision_pool = ProvisionPool(self.config.max_connections, self.config)
+        var executor = SyncExecutor[T](self.config, self._address, self.tcp_keep_alive)
+        self.serve_with_executor(ln, handler, executor)
+
+    fn serve_with_executor[
+        T: HTTPService,
+    ](self, ln: NoTLSListener[NetworkType.tcp4], mut handler: T, mut executor: SyncExecutor[T]) raises ServerError:
+        """Serve HTTP requests using a custom executor for connection dispatch.
 
+        Use this method to provide a custom execution model such as a thread pool
+        or async runtime for handling connections concurrently.
+
+        Parameters:
+            T: The type of HTTPService that handles incoming requests.
+        Args:
+            ln: TCP server that listens for incoming connections.
+            handler: An object that handles incoming HTTP requests.
+            executor: The executor that dispatches each accepted connection.
+
+        Raises:
+            ServerError: If accept fails or critical connection handling errors occur.
+        """
         while True:
             var conn: TCPConnection[NetworkType.tcp4]
             try:
                 conn = ln.accept()
             except listener_err:
                 raise listener_err^
-
-            var index: Int
-            try:
-                index = provision_pool.borrow()
-            except provision_err:
-                # Pool exhausted - close the connection and continue
-                try:
-                    conn^.teardown()
-                except:
-                    pass
-                continue
-
-            try:
-                handle_connection(
-                    conn,
-                    provision_pool.provisions[index],
-                    handler,
-                    self.config,
-                    self.address(),
-                    self.tcp_keep_alive,
-                )
-            except socket_err:
-                # Connection handling failed - just close the connection
-                pass
-            finally:
-                try:
-                    conn^.teardown()
-                except:
-                    pass
-                provision_pool.provisions[index].prepare_for_new_request()
-                provision_pool.provisions[index].keepalive_count = 0
-                provision_pool.release(index)
+            executor.execute(conn^, handler)
 
 
 fn _send_error_response(mut conn: TCPConnection[NetworkType.tcp4], var response: HTTPResponse):