FormStage native reproduction kit — 15 October 2026

1. Inspect the files and use an empty local folder. Node >=22.12 and npm are required.
2. Install the reference server (free npm download):
   npm install --prefix runtime --ignore-scripts chrome-devtools-mcp@1.11.0
3. Supply your separately installed Chrome for Testing executable:
   CFT_PATH="/absolute/path/to/chrome" node native-mcp-probe.mjs
   In PowerShell: $env:CFT_PATH="C:\path\to\chrome.exe"; node native-mcp-probe.mjs

The tested environment is macOS ARM64 / Node25.2.1 / CFT156.0.8078.4. Windows/Linux are unverified.
An isolated browser profile and an ephemeral loopback server are created. No existing browser is attached.
No AI model, payment, API credential, real submission or email is used. The only upload file is synthetic.

The script drives the unmodified MCP server over stdio. Native fill/type/press/upload actions are followed by read-only page observation.
It records native-mcp-results.json, native-tool-schemas.json and, on execution failure, native-mcp-failure.json in this folder.
A changed observation compared with 1.11.0 is recorded, not treated as an automatic regression.
For another version, install that exact package version in runtime and rerun. A changed schema can require a runner update.
Saved output shortens this folder, test-browser and Node paths. Review all output before sharing. Do not substitute private files or values.
The page can observe input effects but cannot independently see MCP errors. Event isTrusted does not identify a human or agent.

Cleanup: the runner closes its own MCP child and loopback server. Delete the unpacked folder when no longer needed.

Sources: https://github.com/ChromeDevTools/chrome-devtools-mcp/issues/3180
https://github.com/ChromeDevTools/chrome-devtools-mcp/issues/3184
https://github.com/ChromeDevTools/chrome-devtools-mcp/pull/3185
Independent project. Not affiliated with Google or any foundation.
