expect-cli crashes on launch: ERR_UNSUPPORTED_DIR_IMPORT (ink → es-toolkit/compat)

[hckhanh]

Expect MCP Server — Connection Failure Context

Summary

The expect MCP server is configured and approved in this repo, but it does not connect because the upstream expect-cli package crashes on launch under Node.js with an ERR_UNSUPPORTED_DIR_IMPORT error originating from ink → es-toolkit/compat.

Repository

• Path: /home/user/untab
• Branch: claude/test-expect-mcp-connection-HA1mw

Configuration (correct, no changes needed)

.mcp.json:

{
  "mcpServers": {
    "expect": {
      "command": "npx",
      "args": ["-y", "expect-cli@latest", "mcp"]
    }
  }
}

.claude/settings.json:

{
  "enabledMcpjsonServers": ["expect"],
  "enabledPlugins": {
    "chrome-devtools-mcp@chrome-devtools-plugins": true
  },
  "extraKnownMarketplaces": {
    "chrome-devtools-plugins": {
      "source": {
        "source": "git",
        "url": "https://github.com/ChromeDevTools/chrome-devtools-mcp.git"
      },
      "autoUpdate": true
    }
  }
}

The server is declared and explicitly enabled. The Claude Code session lists no mcp__expect__* tools, confirming the server failed to start.

Reproduction

npx -y expect-cli@latest --version

Same failure with both:

• Node.js v22.22.2 (system)
• Node.js v24.15.0 (Vite+ runtime via vp env print → /root/.vite-plus/js_runtime/node/24.15.0/bin)

Error

Error [ERR_UNSUPPORTED_DIR_IMPORT]: Directory import
'/root/.npm/_npx/015c9764bdd64143/node_modules/es-toolkit/compat'
is not supported resolving ES modules imported from
/root/.npm/_npx/015c9764bdd64143/node_modules/ink/build/ink.js
Did you mean to import "es-toolkit/compat.js"?
    at finalizeResolution (node:internal/modules/esm/resolve:259:11)
    at moduleResolve (node:internal/modules/esm/resolve:861:10)
    at defaultResolve (node:internal/modules/esm/resolve:988:11)
    ...
  code: 'ERR_UNSUPPORTED_DIR_IMPORT',
  url: 'file:///.../node_modules/es-toolkit/compat'

Root Cause Hypothesis

ink (transitive dependency of expect-cli) imports from 'es-toolkit/compat' — a bare directory specifier. Node's strict ESM resolver rejects this unless the target package's exports map declares the subpath, or the import points at a real file (es-toolkit/compat.js). The version of es-toolkit that gets hoisted in the npx resolution does not expose ./compat as a subpath, so resolution fails before any CLI code runs.

Upstream

• npm package: expect-cli
• Repository: https://github.com/millionco/expect (subdirectory: apps/cli)
• Issues: https://github.com/millionco/expect/issues
• Homepage: https://expect.dev
• Maintainer: Million Software <[founders@million.dev](mailto:founders@million.dev)>

Possible Fixes (any of)

1. Pin ink in expect-cli to a version whose es-toolkit import targets a file path (es-toolkit/compat.js), or one that uses a subpath supported by the es-toolkit exports map.
2. Pin es-toolkit (via expect-cli's lockfile/overrides) to a version that exposes ./compat as a directory subpath in exports.
3. Add an overrides / resolutions block to expect-cli's package.json so the transitive resolution stays aligned with what ink expects.
4. As a temporary workaround for users: pin to a known-good earlier expect-cli version in .mcp.json:

   "args": ["-y", "expect-cli@<known-good-version>", "mcp"]

Impact

• expect-cli is unusable as a CLI (--version, --help, etc. all fail at module resolution).
• The expect MCP server cannot start, so Claude Code sessions in this repo have no mcp__expect__* tools available.
• Affects both Node 22 and Node 24, so a Node downgrade is not a viable workaround.

Suggested Next Steps

1. File the upstream issue at https://github.com/millionco/expect/issues using the body in this document.
2. While waiting on a fix, optionally pin expect-cli to the latest known-working version in .mcp.json and re-approve the server.
3. Re-run a Claude Code session and confirm mcp__expect__* tools appear.

[hckhanh]

Scope clarification: I believes this only reproduces inside the Claude Cloud / cloud-sandbox environment where Claude Code agents run — a restricted Linux container. Two details in the original report are consistent with that: npx writes its cache to /root/.npm/_npx/... (root user inside a container), and the Vite+ runtime path is /root/.vite-plus/.... On a normal local workstation install the failure may not appear, presumably because npm/npx hoists a different es-toolkit version that does expose ./compat as a directory subpath in its exports map.

This doesn't change the fix recommendations — pinning ink/es-toolkit via overrides (or upgrading ink to a version that imports 'es-toolkit/compat.js' instead of the bare directory) would make the package robust against either resolution outcome. But it does explain why a local reproduction attempt may not surface the error.