sdk: "./sdk" export throws at import time — native module resolved outside its own security boundary

Package: @github/copilot
Version affected: 1.0.11
Platform: darwin-arm64

Summary

package.json's "exports" map points the documented import path @github/copilot/sdk at sdk/index.js. That bundle's own require() wrapper enforces a same-directory security check — it resolves the requested module's real path, computes it relative to the bundle's own directory (sdk/), and throws if the relative path starts with .. (i.e. the target lives outside sdk/).

The native pty.node addon this bundle needs at import time lives in the package root's prebuilds/<platform>/ directory — one level outside sdk/. So the check the bundle enforces on itself is violated by the bundle's own required dependency, and import "@github/copilot/sdk" (or any import of sdk/index.js, including by absolute path) throws before a CopilotClient can even be constructed.

Reproduction

// Fails on darwin-arm64, @github/copilot@1.0.11:
import("/opt/homebrew/lib/node_modules/@github/copilot/sdk/index.js")
  .then(m => console.log("OK", Object.keys(m)))
  .catch(e => console.error("ERR", e.message));

The surfaced error is misleading: it reads as Cannot find module './prebuilds/<platform>/pty.node', which looks like an ordinary missing-file error. It is not — it's the last of six internal resolution attempts inside a try/catch loop, and it overwrites the real, earlier error: Requiring module outside of application is a security concern, thrown by the custom require() wrapper on the 5th attempt. Confirmed by instrumenting Module._resolveFilename directly.

Impact

Anyone following the package's own documented entry point (@github/copilot/sdk) for the CLI's JSON-RPC SDK hits this immediately — the import throws, not a runtime session error.

Workaround found

Importing the older copilot-sdk/index.js bundle directly by absolute path instead of the documented @github/copilot/sdk specifier works — it exposes the identical public API (CopilotClient, CopilotSession, defineTool, approveAll, SYSTEM_PROMPT_SECTIONS), uses a plain createRequire(import.meta.url) with no directory-boundary check, and is unaffected.

Suggested fix directions

• Either place sdk/'s security check's allowed root one level higher (package root, not sdk/), or ship prebuilds/ (or a copy/symlink of the needed native module) inside sdk/ so the resolved path never crosses the boundary the check enforces.
• Fix the swallowed-error behavior regardless: the security-check error should not be silently overwritten by a later, unrelated "module not found" from a subsequent resolution attempt in the same try/catch loop — it hides the real cause from anyone hitting this for the first time.

Start with package.json's exports map and sdk/index.js, then reproduce the darwin-arm64 import using the command shown. Trace the resolution attempts to prebuilds//pty.node and the boundary check, including the swallowed error. Done means @github/copilot/sdk imports successfully and failures preserve the original security-check cause.