ERR_MODULE_NOT_FOUND in 0.1.31: session.js missing .js extension on vscode-jsonrpc/node import

[paulwhitten]

Bug

@github/copilot-sdk@0.1.31 crashes on startup under Node.js v24 due to a missing .js file extension on a new import added to dist/session.js.

Same class of defect as #8 (fixed in 0.1.10/0.1.11 for client.js).

Error

Error [ERR_MODULE_NOT_FOUND]: Cannot find module
  '.../node_modules/vscode-jsonrpc/node'
  imported from .../node_modules/@github/copilot-sdk/dist/session.js
Did you mean to import "vscode-jsonrpc/node.js"?

Root Cause

SDK 0.1.31 added a new import to dist/session.js (not present in 0.1.29) that omits the .js extension:

# 0.1.31 session.js line 1 -- NEW import, missing .js
import { ConnectionError, ResponseError } from "vscode-jsonrpc/node";

# 0.1.31 client.js line 10 -- existing import, correct
} from "vscode-jsonrpc/node.js";

The SDK declares "type": "module" (ESM). The dependency vscode-jsonrpc@8.2.1 has no exports map and no "type" field. Without an exports map, Node ESM resolution does not auto-append .js for subpath imports, so "vscode-jsonrpc/node" fails to resolve even though node.js exists in the package root.

dist/client.js already uses the correct "vscode-jsonrpc/node.js" form -- the new session.js import simply did not follow the same convention.

Diff: 0.1.29 / 0.1.30 vs 0.1.31

File	0.1.29	0.1.30	0.1.31
dist/session.js	No vscode-jsonrpc import	No vscode-jsonrpc import	import { ConnectionError, ResponseError } from "vscode-jsonrpc/node" (missing .js)
dist/client.js	from "vscode-jsonrpc/node.js"	from "vscode-jsonrpc/node.js"	from "vscode-jsonrpc/node.js" (unchanged, correct)

Environment

• Affected: 0.1.31
• Working: 0.1.29, 0.1.30
• Node.js: v24.14.0
• OS: Linux

Workaround

Pin to 0.1.30 (or 0.1.29):

"@github/copilot-sdk": "0.1.30"

Suggested Fix

Add .js to the import in the source that produces dist/session.js:

import { ConnectionError, ResponseError } from "vscode-jsonrpc/node.js";

[theblixguy]

I also ran into this in our test suite (vitest with Node ESM). There's another workaround which involves registering a custom module resolution hook before the SDK gets imported:

// filename: fix-jsonrpc-import.js

import { register } from "node:module";

register(
  "data:text/javascript," +
    encodeURIComponent(`
      export function resolve(specifier, context, nextResolve) {
        if (specifier === "vscode-jsonrpc/node") {
          return nextResolve("vscode-jsonrpc/node.js", context);
        }
        return nextResolve(specifier, context);
      }
    `),
  import.meta.url,
);

For vitest, you can drop this in a file and add it to the setupFiles in your config. For plain Node, you can pass it with --import ./fix-jsonrpc-import.js. The hook will intercept the bare vscode-jsonrpc/node specifier and appends .js before Node's default resolver sees it.

It's worth noting that this only affects ESM contexts where Node enforces strict specifier resolution. CJS works fine and so do bundlers like tsx, since they handle extension-less imports on their own.