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fix: add POST /sse handler for MCP Streamable HTTP transport (Claude.ai new protocol)

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colorlink
2026-05-08 21:59:11 +00:00
parent 068a1d8bf8
commit 310183f03b
1 changed files with 108 additions and 64 deletions
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includes/MCP/Server.php
+108 -64
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@@ -5,15 +5,15 @@ namespace AskTamMCP\MCP;
defined('ABSPATH') || exit;
/**
* MCP Server — Streamable HTTP transport (2025-03-26 spec).
* MCP Server — supports both transports:
*
* Claude.ai uses POST /sse for all communication (not GET SSE stream).
* Each POST carries a JSON-RPC message and gets a direct JSON response.
* We also keep GET /sse for legacy clients that expect SSE streams.
* 1. Streamable HTTP (new, Claude.ai uses this):
* POST /sse with Accept: application/json → returns JSON-RPC response directly
* POST /sse with Accept: text/event-stream → streams SSE response
*
* POST /sse — Claude.ai sends JSON-RPC, gets JSON-RPC response
* GET /sse — legacy SSE stream for other MCP clients
* POST /message — explicit message endpoint (also supported)
* 2. Legacy SSE (old):
* GET /sse → opens SSE stream, sends endpoint event
* POST /message → handles JSON-RPC messages
*/
class Server {
@@ -24,7 +24,7 @@ class Server {
}
public function registerRoutes(): void {
// SSE endpoint — GET for legacy stream, POST for Claude.ai streamable HTTP
// Primary endpoint — accepts both GET (legacy SSE) and POST (streamable HTTP)
register_rest_route('asktam-mcp/v1', '/sse', [
[
'methods' => 'GET',
@@ -38,7 +38,7 @@ class Server {
],
]);
// Explicit message endpoint
// Legacy message endpoint (used by old SSE transport)
register_rest_route('asktam-mcp/v1', '/message', [
'methods' => 'POST',
'callback' => [$this, 'handleMessage'],
@@ -53,20 +53,53 @@ class Server {
}
// -------------------------------------------------------------------------
// POST /sse — Streamable HTTP transport (Claude.ai 2025+)
// Each request is a JSON-RPC message, response is JSON-RPC
// Streamable HTTP transport — POST /sse
// Claude.ai sends JSON-RPC here, we respond with JSON or SSE stream
// -------------------------------------------------------------------------
public function handleSsePost(\WP_REST_Request $request): \WP_REST_Response|\WP_Error {
public function handleSsePost(\WP_REST_Request $request): void {
$auth = \AskTamMCP\Core\Auth::validate($request, \AskTamMCP\Core\Auth::SCOPE_READ);
if (is_wp_error($auth)) {
return $auth;
status_header($auth->get_error_data()['status'] ?? 401);
header('Content-Type: application/json');
echo wp_json_encode(['error' => $auth->get_error_message()]);
exit;
}
return $this->dispatchJsonRpc($request, $auth);
$body = $request->get_json_params() ?? [];
$accept = $request->get_header('Accept') ?? '';
// Determine if client wants SSE stream or plain JSON
$wantsStream = str_contains($accept, 'text/event-stream');
// Handle batch requests (array of JSON-RPC calls)
if (isset($body[0])) {
$results = [];
foreach ($body as $msg) {
$result = $this->dispatchJsonRpc($msg, $auth);
if ($result !== null) {
$results[] = $result;
}
}
if ($wantsStream) {
$this->streamJsonRpcResponses($results);
} else {
$this->jsonResponse($results);
}
return;
}
// Single JSON-RPC message
$result = $this->dispatchJsonRpc($body, $auth);
if ($wantsStream) {
$this->streamJsonRpcResponses($result ? [$result] : []);
} else {
$this->jsonResponse($result ?? new \stdClass());
}
}
// -------------------------------------------------------------------------
// GET /sse — Legacy SSE stream for non-Claude.ai clients
// Legacy SSE transport — GET /sse
// -------------------------------------------------------------------------
public function handleSseGet(\WP_REST_Request $request): void {
$auth = \AskTamMCP\Core\Auth::validate($request, \AskTamMCP\Core\Auth::SCOPE_READ);
@@ -88,7 +121,6 @@ class Server {
header('Access-Control-Allow-Origin: *');
$messageEndpoint = rest_url('asktam-mcp/v1/message');
$this->sseEvent('endpoint', $messageEndpoint);
$this->sseEvent('message', wp_json_encode([
'jsonrpc' => '2.0',
@@ -115,46 +147,35 @@ class Server {
}
// -------------------------------------------------------------------------
// POST /message — explicit endpoint (same as POST /sse)
// Legacy message handler — POST /message
// -------------------------------------------------------------------------
public function handleMessage(\WP_REST_Request $request): \WP_REST_Response|\WP_Error {
$auth = \AskTamMCP\Core\Auth::validate($request, \AskTamMCP\Core\Auth::SCOPE_READ);
if (is_wp_error($auth)) {
return $auth;
}
if (is_wp_error($auth)) return $auth;
return $this->dispatchJsonRpc($request, $auth);
$body = $request->get_json_params();
$result = $this->dispatchJsonRpc($body ?? [], $auth);
return new \WP_REST_Response(
$result ?? ['jsonrpc' => '2.0', 'id' => null, 'result' => null],
200
);
}
public function handleInfo(): \WP_REST_Response {
return new \WP_REST_Response([
'name' => 'Advanced MCP Plugin by AskTam',
'version' => ASKTAM_MCP_VERSION,
'endpoint' => rest_url('asktam-mcp/v1/sse'),
'transport' => 'streamable-http',
'mcp_version' => '2025-03-26',
'name' => 'Advanced MCP Plugin by AskTam',
'version' => ASKTAM_MCP_VERSION,
'endpoint' => rest_url('asktam-mcp/v1/sse'),
'transport' => ['streamable-http', 'sse'],
]);
}
// -------------------------------------------------------------------------
// Shared JSON-RPC dispatcher
// Core JSON-RPC dispatcher — shared by all transports
// -------------------------------------------------------------------------
private function dispatchJsonRpc(\WP_REST_Request $request, array $auth): \WP_REST_Response {
$body = $request->get_json_params();
if (empty($body)) {
// Claude.ai sometimes sends empty POST to initialize connection
// Return capabilities immediately
return $this->rpcResult(null, [
'protocolVersion' => '2024-11-05',
'capabilities' => ['tools' => ['listChanged' => false]],
'serverInfo' => ['name' => 'advanced-mcp-plugin', 'version' => ASKTAM_MCP_VERSION],
]);
}
if (empty($body['method'])) {
return $this->rpcError(null, -32600, 'Invalid Request: missing method');
}
private function dispatchJsonRpc(array $body, array $authRow): ?array {
if (empty($body['method'])) return null;
$id = $body['id'] ?? null;
$method = $body['method'];
@@ -172,29 +193,59 @@ class Server {
return $this->rpcResult($id, ['tools' => $this->registry->getToolDefinitions()]);
case 'tools/call':
return $this->handleToolCall($id, $params, $auth);
return $this->handleToolCall($id, $params, $authRow);
case 'notifications/initialized':
case 'notifications/cancelled':
return new \WP_REST_Response(null, 204);
return null; // notifications get no response
default:
return $this->rpcError($id, -32601, "Method not found: {$method}");
}
}
private function handleToolCall(mixed $id, array $params, array $authRow): \WP_REST_Response {
// -------------------------------------------------------------------------
// Output helpers
// -------------------------------------------------------------------------
private function streamJsonRpcResponses(array $responses): void {
while (ob_get_level()) ob_end_clean();
header('Content-Type: text/event-stream; charset=UTF-8');
header('Cache-Control: no-cache, no-store');
header('X-Accel-Buffering: no');
header('Access-Control-Allow-Origin: *');
foreach ($responses as $response) {
$this->sseEvent('message', wp_json_encode($response));
}
// Send done marker
echo "event: done\ndata: \n\n";
flush();
exit;
}
private function jsonResponse(mixed $data): void {
while (ob_get_level()) ob_end_clean();
header('Content-Type: application/json; charset=UTF-8');
header('Access-Control-Allow-Origin: *');
echo wp_json_encode($data);
flush();
exit;
}
private function sseEvent(string $event, string $data): void {
echo "event: {$event}\ndata: {$data}\n\n";
flush();
}
private function handleToolCall(mixed $id, array $params, array $authRow): array {
$toolName = $params['name'] ?? '';
$arguments = $params['arguments'] ?? [];
if (empty($toolName)) {
return $this->rpcError($id, -32602, 'Missing tool name');
}
if (empty($toolName)) return $this->rpcError($id, -32602, 'Missing tool name');
$handler = $this->registry->getHandler($toolName);
if (!$handler) {
return $this->rpcError($id, -32601, "Unknown tool: {$toolName}");
}
if (!$handler) return $this->rpcError($id, -32601, "Unknown tool: {$toolName}");
$tool = $this->registry->getTool($toolName);
$required = $tool['scope'] ?? 'read';
@@ -208,25 +259,18 @@ class Server {
try {
$result = $handler($arguments);
return $this->rpcResult($id, [
'content' => [
['type' => 'text', 'text' => is_string($result) ? $result : wp_json_encode($result)],
],
'content' => [['type' => 'text', 'text' => is_string($result) ? $result : wp_json_encode($result)]],
]);
} catch (\Throwable $e) {
return $this->rpcError($id, -32000, $e->getMessage());
}
}
private function rpcResult(mixed $id, mixed $result): \WP_REST_Response {
return new \WP_REST_Response(['jsonrpc' => '2.0', 'id' => $id, 'result' => $result]);
private function rpcResult(mixed $id, mixed $result): array {
return ['jsonrpc' => '2.0', 'id' => $id, 'result' => $result];
}
private function rpcError(mixed $id, int $code, string $message): \WP_REST_Response {
return new \WP_REST_Response(['jsonrpc' => '2.0', 'id' => $id, 'error' => ['code' => $code, 'message' => $message]], 200);
}
private function sseEvent(string $event, string $data): void {
echo "event: {$event}\ndata: {$data}\n\n";
flush();
private function rpcError(mixed $id, int $code, string $message): array {
return ['jsonrpc' => '2.0', 'id' => $id, 'error' => ['code' => $code, 'message' => $message]];
}
}