fix(perf): bound sharp screenshot memory in hosted mode to prevent pod OOM

src/lib/utils.ts

@@ -5,13 +5,15 @@ import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
 import { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
 import { trackMCP } from "../index.js";
 import logger from "../logger.js";
+import globalConfig from "../config.js";
 
 export function sanitizeUrlParam(param: string): string {
   // Remove any characters that could be used for command injection
   return param.replace(/[;&|`$(){}[\]<>]/g, "");
 }
 
 const ONE_MB = 1048576;
+let sharpConfigured = false;
 
 //Compresses a base64 image intelligently to keep it under 1 MB if needed.
 export async function maybeCompressBase64(base64: string): Promise<string> {
@@ -27,6 +29,12 @@ export async function maybeCompressBase64(base64: string): Promise<string> {
 
   try {
     const { default: sharp } = await import("sharp");
+    if (!sharpConfigured && globalConfig.REMOTE_MCP) {
+      // Bound memory on constrained hosted pods: no libvips cache, single worker thread.
+      sharp.cache(false);
+      sharp.concurrency(1);
+      sharpConfigured = true;
+    }
     const compressedBuffer = await sharp(buffer).png({ quality }).toBuffer();
     return compressedBuffer.toString("base64");
   } catch (err) {

src/tools/automate-utils/fetch-screenshots.ts

@@ -3,6 +3,7 @@ import { SessionType } from "../../lib/constants.js";
 import { getBrowserStackAuth } from "../../lib/get-auth.js";
 import { BrowserStackConfig } from "../../lib/types.js";
 import { apiClient } from "../../lib/apiClient.js";
+import globalConfig from "../../config.js";
 
 async function extractScreenshotUrls(
   sessionId: string,
@@ -53,30 +54,30 @@ async function extractScreenshotUrls(
   return urls;
 }
 
+async function fetchAndCompress(
+  url: string,
+): Promise<{ url: string; base64: string }> {
+  const response = await apiClient.get({ url, responseType: "arraybuffer" });
+  // Axios returns response.data as a Buffer for binary data
+  const base64 = Buffer.from(response.data).toString("base64");
+  return { url, base64: await maybeCompressBase64(base64) };
+}
+
 //Converts screenshot URLs to base64 encoded images
 async function convertUrlsToBase64(
   urls: string[],
 ): Promise<Array<{ url: string; base64: string }>> {
-  const screenshots = await Promise.all(
-    urls.map(async (url) => {
-      const response = await apiClient.get({
-        url,
-        responseType: "arraybuffer",
-      });
-      // Axios returns response.data as a Buffer for binary data
-      const base64 = Buffer.from(response.data).toString("base64");
-
-      // Compress the base64 image if needed
-      const compressedBase64 = await maybeCompressBase64(base64);
-
-      return {
-        url,
-        base64: compressedBase64,
-      };
-    }),
-  );
+  // Hosted pods are memory-constrained: process one image at a time. Local runs
+  // keep the concurrent path.
+  if (globalConfig.REMOTE_MCP) {
+    const screenshots: Array<{ url: string; base64: string }> = [];
+    for (const url of urls) {
+      screenshots.push(await fetchAndCompress(url));
+    }
+    return screenshots;
+  }
 
-  return screenshots;
+  return Promise.all(urls.map(fetchAndCompress));
 }
 
 //Fetches and converts screenshot URLs to base64 encoded images

tests/setup.ts

@@ -1,10 +1,13 @@
 import { vi } from "vitest";
 
 // Mock sharp globally — it's a native binary module that may not be available in CI
-vi.mock("sharp", () => ({
-  default: vi.fn().mockReturnValue({
+vi.mock("sharp", () => {
+  const sharp: any = vi.fn().mockReturnValue({
     png: vi.fn().mockReturnValue({
       toBuffer: vi.fn().mockResolvedValue(Buffer.from("mock-image")),
     }),
-  }),
-}));
+  });
+  sharp.cache = vi.fn();
+  sharp.concurrency = vi.fn();
+  return { default: sharp };
+});