Fix plugin SDK worker entrypoint symlink check

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/plugins/sdk/src/worker-rpc-host.ts

@@ -34,6 +34,7 @@
  * @see PLUGIN_SPEC.md §14 — SDK Surface
  */
 
+import fs from "node:fs";
 import path from "node:path";
 import { createInterface, type Interface as ReadlineInterface } from "node:readline";
 import { fileURLToPath } from "node:url";
@@ -175,6 +176,21 @@ interface EventRegistration {
 /** Default timeout for worker→host RPC calls. */
 const DEFAULT_RPC_TIMEOUT_MS = 30_000;
 
+function realpathOrResolvedPath(filePath: string): string {
+  const resolvedPath = path.resolve(filePath);
+  try {
+    return fs.realpathSync.native(resolvedPath);
+  } catch {
+    return resolvedPath;
+  }
+}
+
+export function isWorkerEntrypoint(entry: string, moduleUrl: string): boolean {
+  const thisFile = realpathOrResolvedPath(fileURLToPath(moduleUrl));
+  const entryPath = realpathOrResolvedPath(entry);
+  return thisFile === entryPath;
+}
+
 // ---------------------------------------------------------------------------
 // startWorkerRpcHost
 // ---------------------------------------------------------------------------
@@ -223,9 +239,7 @@ export function runWorker(
   }
   const entry = process.argv[1];
   if (typeof entry !== "string") return;
-  const thisFile = path.resolve(fileURLToPath(moduleUrl));
-  const entryPath = path.resolve(entry);
-  if (thisFile === entryPath) {
+  if (isWorkerEntrypoint(entry, moduleUrl)) {
     startWorkerRpcHost({ plugin });
   }
 }

packages/plugins/sdk/tests/worker-rpc-host.test.ts

@@ -0,0 +1,57 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { pathToFileURL } from "node:url";
+
+import { afterEach, describe, expect, it } from "vitest";
+
+import { isWorkerEntrypoint } from "../src/worker-rpc-host.js";
+
+describe("isWorkerEntrypoint", () => {
+  const tempRoots: string[] = [];
+
+  afterEach(() => {
+    for (const tempRoot of tempRoots.splice(0)) {
+      fs.rmSync(tempRoot, { recursive: true, force: true });
+    }
+  });
+
+  function createTempRoot(): string {
+    const tempRoot = fs.mkdtempSync(path.join(os.tmpdir(), "paperclip-sdk-worker-"));
+    tempRoots.push(tempRoot);
+    return tempRoot;
+  }
+
+  it("matches an entrypoint reached through a symlinked directory", () => {
+    const tempRoot = createTempRoot();
+    const realDir = path.join(tempRoot, "real");
+    const linkDir = path.join(tempRoot, "link");
+    fs.mkdirSync(realDir);
+    fs.symlinkSync(realDir, linkDir, "dir");
+
+    const workerPath = path.join(realDir, "worker.js");
+    fs.writeFileSync(workerPath, "");
+
+    expect(
+      isWorkerEntrypoint(
+        path.join(linkDir, "worker.js"),
+        pathToFileURL(workerPath).toString(),
+      ),
+    ).toBe(true);
+  });
+
+  it("does not match a different entrypoint", () => {
+    const tempRoot = createTempRoot();
+    const workerPath = path.join(tempRoot, "worker.js");
+    const otherPath = path.join(tempRoot, "other.js");
+    fs.writeFileSync(workerPath, "");
+    fs.writeFileSync(otherPath, "");
+
+    expect(
+      isWorkerEntrypoint(
+        otherPath,
+        pathToFileURL(workerPath).toString(),
+      ),
+    ).toBe(false);
+  });
+});

packages/plugins/sdk/vitest.config.ts

@@ -0,0 +1,8 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    environment: "node",
+    include: ["tests/**/*.test.ts"],
+  },
+});

scripts/run-vitest-stable.mjs

@@ -14,6 +14,7 @@ const nonServerProjects = [
   "@paperclipai/adapter-acpx-local",
   "@paperclipai/adapter-codex-local",
   "@paperclipai/adapter-opencode-local",
+  "@paperclipai/plugin-sdk",
   "@paperclipai/ui",
   "paperclipai",
 ];

vitest.config.ts

@@ -14,6 +14,7 @@ export default defineConfig({
       "packages/adapters/gemini-local",
       "packages/adapters/opencode-local",
       "packages/adapters/pi-local",
+      "packages/plugins/sdk",
       "server",
       "ui",
       "cli",