chore(internal): make MCP code execution location configurable via a flag

Author: stainless-app[bot]

packages/mcp-server/Dockerfile

@@ -37,9 +37,21 @@ COPY . .
 RUN yarn install --frozen-lockfile && \
     yarn build
 
-# Production stage
+FROM denoland/deno:bin-2.6.10 AS deno_installer
+FROM gcr.io/distroless/cc@sha256:66d87e170bc2c5e2b8cf853501141c3c55b4e502b8677595c57534df54a68cc5 AS cc
+
 FROM node:24-alpine
 
+# Install deno
+COPY --from=deno_installer /deno /usr/local/bin/deno
+
+# Add in shared libraries needed by Deno
+COPY --from=cc --chown=root:root --chmod=755 /lib/*-linux-gnu/* /usr/local/lib/
+COPY --from=cc --chown=root:root --chmod=755 /lib/ld-linux-* /lib/
+
+RUN mkdir /lib64 && ln -s /usr/local/lib/ld-linux-* /lib64/
+ENV LD_LIBRARY_PATH=/usr/lib:/usr/local/lib
+
 # Add non-root user
 RUN addgroup -g 1001 -S nodejs && adduser -S nodejs -u 1001
 

packages/mcp-server/src/code-tool-paths.cts

@@ -0,0 +1,3 @@
+// File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
+
+export const workerPath = require.resolve('./code-tool-worker.mjs');

packages/mcp-server/src/code-tool-types.ts

@@ -8,6 +8,7 @@ export type WorkerInput = {
   client_opts: ClientOptions;
   intent?: string | undefined;
 };
+
 export type WorkerOutput = {
   is_error: boolean;
   result: unknown | null;

packages/mcp-server/src/code-tool-worker.ts

@@ -0,0 +1,319 @@
+// File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
+
+import path from 'node:path';
+import util from 'node:util';
+import Fuse from 'fuse.js';
+import ts from 'typescript';
+import { WorkerOutput } from './code-tool-types';
+import { ImageKit, ClientOptions } from '@imagekit/nodejs';
+
+function getRunFunctionSource(code: string): {
+  type: 'declaration' | 'expression';
+  client: string | undefined;
+  code: string;
+} | null {
+  const sourceFile = ts.createSourceFile('code.ts', code, ts.ScriptTarget.Latest, true);
+  const printer = ts.createPrinter();
+
+  for (const statement of sourceFile.statements) {
+    // Check for top-level function declarations
+    if (ts.isFunctionDeclaration(statement)) {
+      if (statement.name?.text === 'run') {
+        return {
+          type: 'declaration',
+          client: statement.parameters[0]?.name.getText(),
+          code: printer.printNode(ts.EmitHint.Unspecified, statement.body!, sourceFile),
+        };
+      }
+    }
+
+    // Check for variable declarations: const run = () => {} or const run = function() {}
+    if (ts.isVariableStatement(statement)) {
+      for (const declaration of statement.declarationList.declarations) {
+        if (
+          ts.isIdentifier(declaration.name) &&
+          declaration.name.text === 'run' &&
+          // Check if it's initialized with a function
+          declaration.initializer &&
+          (ts.isFunctionExpression(declaration.initializer) || ts.isArrowFunction(declaration.initializer))
+        ) {
+          return {
+            type: 'expression',
+            client: declaration.initializer.parameters[0]?.name.getText(),
+            code: printer.printNode(ts.EmitHint.Unspecified, declaration.initializer, sourceFile),
+          };
+        }
+      }
+    }
+  }
+
+  return null;
+}
+
+function getTSDiagnostics(code: string): string[] {
+  const functionSource = getRunFunctionSource(code)!;
+  const codeWithImport = [
+    'import { ImageKit } from "@imagekit/nodejs";',
+    functionSource.type === 'declaration' ?
+      `async function run(${functionSource.client}: ImageKit)`
+    : `const run: (${functionSource.client}: ImageKit) => Promise<unknown> =`,
+    functionSource.code,
+  ].join('\n');
+  const sourcePath = path.resolve('code.ts');
+  const ast = ts.createSourceFile(sourcePath, codeWithImport, ts.ScriptTarget.Latest, true);
+  const options = ts.getDefaultCompilerOptions();
+  options.target = ts.ScriptTarget.Latest;
+  options.module = ts.ModuleKind.NodeNext;
+  options.moduleResolution = ts.ModuleResolutionKind.NodeNext;
+  const host = ts.createCompilerHost(options, true);
+  const newHost: typeof host = {
+    ...host,
+    getSourceFile: (...args) => {
+      if (path.resolve(args[0]) === sourcePath) {
+        return ast;
+      }
+      return host.getSourceFile(...args);
+    },
+    readFile: (...args) => {
+      if (path.resolve(args[0]) === sourcePath) {
+        return codeWithImport;
+      }
+      return host.readFile(...args);
+    },
+    fileExists: (...args) => {
+      if (path.resolve(args[0]) === sourcePath) {
+        return true;
+      }
+      return host.fileExists(...args);
+    },
+  };
+  const program = ts.createProgram({
+    options,
+    rootNames: [sourcePath],
+    host: newHost,
+  });
+  const diagnostics = ts.getPreEmitDiagnostics(program, ast);
+  return diagnostics.map((d) => {
+    const message = ts.flattenDiagnosticMessageText(d.messageText, '\n');
+    if (!d.file || !d.start) return `- ${message}`;
+    const { line: lineNumber } = ts.getLineAndCharacterOfPosition(d.file, d.start);
+    const line = codeWithImport.split('\n').at(lineNumber)?.trim();
+    return line ? `- ${message}\n    ${line}` : `- ${message}`;
+  });
+}
+
+const fuse = new Fuse(
+  [
+    'client.customMetadataFields.create',
+    'client.customMetadataFields.delete',
+    'client.customMetadataFields.list',
+    'client.customMetadataFields.update',
+    'client.files.copy',
+    'client.files.delete',
+    'client.files.get',
+    'client.files.move',
+    'client.files.rename',
+    'client.files.update',
+    'client.files.upload',
+    'client.files.bulk.addTags',
+    'client.files.bulk.delete',
+    'client.files.bulk.removeAITags',
+    'client.files.bulk.removeTags',
+    'client.files.versions.delete',
+    'client.files.versions.get',
+    'client.files.versions.list',
+    'client.files.versions.restore',
+    'client.files.metadata.get',
+    'client.files.metadata.getFromURL',
+    'client.savedExtensions.create',
+    'client.savedExtensions.delete',
+    'client.savedExtensions.get',
+    'client.savedExtensions.list',
+    'client.savedExtensions.update',
+    'client.assets.list',
+    'client.cache.invalidation.create',
+    'client.cache.invalidation.get',
+    'client.folders.copy',
+    'client.folders.create',
+    'client.folders.delete',
+    'client.folders.move',
+    'client.folders.rename',
+    'client.folders.job.get',
+    'client.accounts.usage.get',
+    'client.accounts.origins.create',
+    'client.accounts.origins.delete',
+    'client.accounts.origins.get',
+    'client.accounts.origins.list',
+    'client.accounts.origins.update',
+    'client.accounts.urlEndpoints.create',
+    'client.accounts.urlEndpoints.delete',
+    'client.accounts.urlEndpoints.get',
+    'client.accounts.urlEndpoints.list',
+    'client.accounts.urlEndpoints.update',
+    'client.beta.v2.files.upload',
+    'client.webhooks.unsafeUnwrap',
+    'client.webhooks.unwrap',
+  ],
+  { threshold: 1, shouldSort: true },
+);
+
+function getMethodSuggestions(fullyQualifiedMethodName: string): string[] {
+  return fuse
+    .search(fullyQualifiedMethodName)
+    .map(({ item }) => item)
+    .slice(0, 5);
+}
+
+const proxyToObj = new WeakMap<any, any>();
+const objToProxy = new WeakMap<any, any>();
+
+type ClientProxyConfig = {
+  path: string[];
+  isBelievedBad?: boolean;
+};
+
+function makeSdkProxy<T extends object>(obj: T, { path, isBelievedBad = false }: ClientProxyConfig): T {
+  let proxy: T = objToProxy.get(obj);
+
+  if (!proxy) {
+    proxy = new Proxy(obj, {
+      get(target, prop, receiver) {
+        const propPath = [...path, String(prop)];
+        const value = Reflect.get(target, prop, receiver);
+
+        if (isBelievedBad || (!(prop in target) && value === undefined)) {
+          // If we're accessing a path that doesn't exist, it will probably eventually error.
+          // Let's proxy it and mark it bad so that we can control the error message.
+          // We proxy an empty class so that an invocation or construction attempt is possible.
+          return makeSdkProxy(class {}, { path: propPath, isBelievedBad: true });
+        }
+
+        if (value !== null && (typeof value === 'object' || typeof value === 'function')) {
+          return makeSdkProxy(value, { path: propPath, isBelievedBad });
+        }
+
+        return value;
+      },
+
+      apply(target, thisArg, args) {
+        if (isBelievedBad || typeof target !== 'function') {
+          const fullyQualifiedMethodName = path.join('.');
+          const suggestions = getMethodSuggestions(fullyQualifiedMethodName);
+          throw new Error(
+            `${fullyQualifiedMethodName} is not a function. Did you mean: ${suggestions.join(', ')}`,
+          );
+        }
+
+        return Reflect.apply(target, proxyToObj.get(thisArg) ?? thisArg, args);
+      },
+
+      construct(target, args, newTarget) {
+        if (isBelievedBad || typeof target !== 'function') {
+          const fullyQualifiedMethodName = path.join('.');
+          const suggestions = getMethodSuggestions(fullyQualifiedMethodName);
+          throw new Error(
+            `${fullyQualifiedMethodName} is not a constructor. Did you mean: ${suggestions.join(', ')}`,
+          );
+        }
+
+        return Reflect.construct(target, args, newTarget);
+      },
+    });
+
+    objToProxy.set(obj, proxy);
+    proxyToObj.set(proxy, obj);
+  }
+
+  return proxy;
+}
+
+function parseError(code: string, error: unknown): string | undefined {
+  if (!(error instanceof Error)) return;
+  const message = error.name ? `${error.name}: ${error.message}` : error.message;
+  try {
+    // Deno uses V8; the first "<anonymous>:LINE:COLUMN" is the top of stack.
+    const lineNumber = error.stack?.match(/<anonymous>:([0-9]+):[0-9]+/)?.[1];
+    // -1 for the zero-based indexing
+    const line =
+      lineNumber &&
+      code
+        .split('\n')
+        .at(parseInt(lineNumber, 10) - 1)
+        ?.trim();
+    return line ? `${message}\n  at line ${lineNumber}\n    ${line}` : message;
+  } catch {
+    return message;
+  }
+}
+
+const fetch = async (req: Request): Promise<Response> => {
+  const { opts, code } = (await req.json()) as { opts: ClientOptions; code: string };
+
+  const runFunctionSource = code ? getRunFunctionSource(code) : null;
+  if (!runFunctionSource) {
+    const message =
+      code ?
+        'The code is missing a top-level `run` function.'
+      : 'The code argument is missing. Provide one containing a top-level `run` function.';
+    return Response.json(
+      {
+        is_error: true,
+        result: `${message} Write code within this template:\n\n\`\`\`\nasync function run(client) {\n  // Fill this out\n}\n\`\`\``,
+        log_lines: [],
+        err_lines: [],
+      } satisfies WorkerOutput,
+      { status: 400, statusText: 'Code execution error' },
+    );
+  }
+
+  const diagnostics = getTSDiagnostics(code);
+  if (diagnostics.length > 0) {
+    return Response.json(
+      {
+        is_error: true,
+        result: `The code contains TypeScript diagnostics:\n${diagnostics.join('\n')}`,
+        log_lines: [],
+        err_lines: [],
+      } satisfies WorkerOutput,
+      { status: 400, statusText: 'Code execution error' },
+    );
+  }
+
+  const client = new ImageKit({
+    ...opts,
+  });
+
+  const log_lines: string[] = [];
+  const err_lines: string[] = [];
+  const console = {
+    log: (...args: unknown[]) => {
+      log_lines.push(util.format(...args));
+    },
+    error: (...args: unknown[]) => {
+      err_lines.push(util.format(...args));
+    },
+  };
+  try {
+    let run_ = async (client: any) => {};
+    eval(`${code}\nrun_ = run;`);
+    const result = await run_(makeSdkProxy(client, { path: ['client'] }));
+    return Response.json({
+      is_error: false,
+      result,
+      log_lines,
+      err_lines,
+    } satisfies WorkerOutput);
+  } catch (e) {
+    return Response.json(
+      {
+        is_error: true,
+        result: parseError(code, e),
+        log_lines,
+        err_lines,
+      } satisfies WorkerOutput,
+      { status: 400, statusText: 'Code execution error' },
+    );
+  }
+};
+
+export default { fetch };