Soften MCP SSE rotation max age (#1318)

Author: RhysSullivan

packages/hosts/cloudflare/src/mcp/agents-sse-max-age.test.ts

@@ -2,6 +2,8 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "@effect/vitest"
 import { MAX_SSE_AGE_MS, McpAgent } from "agents/mcp";
 import { Effect, Option, Schema } from "effect";
 
+import { SESSION_TIMEOUT_MS } from "./session-alarm-policy";
+
 const KEEPALIVE_INTERVAL_MS = 25_000;
 const MAX_PENDING_SSE_BYTES = 8 * 1024 * 1024;
 
@@ -264,6 +266,11 @@ describe("agents SSE max-age rotation", () => {
     vi.useRealTimers();
   });
 
+  it("keeps the default max age well above the session idle timeout", () => {
+    expect(MAX_SSE_AGE_MS).toBe(30 * 60 * 1000);
+    expect(MAX_SSE_AGE_MS).toBeGreaterThanOrEqual(6 * SESSION_TIMEOUT_MS);
+  });
+
   it("closes a healthy draining SSE connection within one keepalive tick after max age", async () => {
     const { response, ws } = await openSse();
     const drained = drainResponse(response);

patches/agents@0.17.3.patch

@@ -6,7 +6,7 @@ index c8fad448e8797b89690a99d93490d1363851b225..439da01e789713d217778e8bdebfa1a9
    xt as MCPClientOAuthCallbackConfig,
    zt as ElicitResult
  } from "../agent-tool-types-CNyE1iz_.js";
-+declare const MAX_SSE_AGE_MS = 300000;
++declare const MAX_SSE_AGE_MS = 1800000;
  export {
    type ClearableEventStore,
    type CreateMcpHandlerOptions,
@@ -22,11 +22,14 @@ diff --git a/dist/mcp/index.js b/dist/mcp/index.js
 index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..0ba4f5bff8e6a968aa18c609952e576cedf13d8f 100644
 --- a/dist/mcp/index.js
 +++ b/dist/mcp/index.js
-@@ -28,13 +28,14 @@ import { WebStandardStreamableHTTPServerTransport } from "@modelcontextprotocol/
+@@ -28,13 +28,17 @@ import { WebStandardStreamableHTTPServerTransport } from "@modelcontextprotocol/
  const KEEPALIVE_INTERVAL_MS = 25e3;
  /** SSE comment frame the parser drops before any event dispatch. */
  const KEEPALIVE_FRAME = ": keepalive\n\n";
-+const MAX_SSE_AGE_MS = 300_000;
++// Max age is a stalled-client memory backstop, not session idleness. Keep it
++// well above Executor's 5 minute session idle timeout so active clients rarely
++// rotate.
++const MAX_SSE_AGE_MS = 30 * 60 * 1000;
  /**
  * Start an SSE keepalive on `writer`. Returns a `clearInterval` handle
  * that the stream cleanup must invoke when the stream closes.
@@ -39,7 +42,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..0ba4f5bff8e6a968aa18c609952e576c
  	}, KEEPALIVE_INTERVAL_MS);
  	return handle;
  }
-@@ -180,10 +181,15 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
+@@ -180,10 +184,15 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
  					});
  					return new Response(body, { status: 404 });
  				}
@@ -59,7 +62,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..0ba4f5bff8e6a968aa18c609952e576c
  				request.headers.forEach((value, key) => {
  					existingHeaders[key] = value;
  				});
-@@ -206,45 +212,71 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
+@@ -206,45 +215,71 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
  						jsonrpc: "2.0"
  					});
  					return new Response(body, { status: 500 });
@@ -157,7 +160,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..0ba4f5bff8e6a968aa18c609952e576c
  					}
  					onClose().catch(console.error);
  				});
-@@ -279,10 +311,16 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
+@@ -279,10 +314,16 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
  					id: null,
  					jsonrpc: "2.0"
  				}), { status: 400 });
@@ -178,7 +181,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..0ba4f5bff8e6a968aa18c609952e576c
  					props: ctx.props,
  					jurisdiction: options.jurisdiction
  				});
-@@ -306,27 +344,86 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
+@@ -306,27 +347,86 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
  				if (!ws) {
  					await writer.close();
  					return new Response("Failed to establish WS to DO", { status: 500 });
@@ -280,7 +283,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..0ba4f5bff8e6a968aa18c609952e576c
  				return new Response(readable, {
  					headers: {
  						"Cache-Control": "no-cache",
-@@ -389,10 +486,16 @@ const createLegacySseHandler = (basePath, namespace, options = {}) => {
+@@ -389,10 +489,16 @@ const createLegacySseHandler = (basePath, namespace, options = {}) => {
  		const url = new URL(request.url);
  		if (request.method === "GET" && basePattern.test(url)) {
  			const sessionId = url.searchParams.get("sessionId") || namespace.newUniqueId().toString();
@@ -301,7 +304,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..0ba4f5bff8e6a968aa18c609952e576c
  			endpointUrl.pathname = encodeURI(`${basePath}/message`);
  			endpointUrl.searchParams.set("sessionId", sessionId);
  			const endpointMessage = `event: endpoint\ndata: ${endpointUrl.pathname + endpointUrl.search + endpointUrl.hash}\n\n`;
-@@ -414,35 +517,94 @@ const createLegacySseHandler = (basePath, namespace, options = {}) => {
+@@ -414,35 +520,94 @@ const createLegacySseHandler = (basePath, namespace, options = {}) => {
  				console.error("Failed to establish WebSocket connection");
  				await writer.close();
  				return new Response("Failed to establish WebSocket connection", { status: 500 });
@@ -414,7 +417,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..0ba4f5bff8e6a968aa18c609952e576c
  						console.error("Error closing SSE connection:", error);
  					}
  				}
-@@ -1698,6 +1860,6 @@ var McpAgent = class McpAgent extends Agent {
+@@ -1698,6 +1863,6 @@ var McpAgent = class McpAgent extends Agent {
  };
  McpAgent.STREAM_REQS_KEY_PREFIX = "__mcp_stream_reqs__:";
  //#endregion