feat: use an env variable VITE_MCP_SERVER_URL to make it possible that devtools can point at a different url

[ppshobi]

see #444

This pull request adds a support that the devtools can point at a different mcp server url than the hardcoded localhost:3000/mcp. while defaulting to the same

Greptile Overview

Greptile Summary

This PR changes the devtools MCP client initialization to allow overriding the default MCP endpoint (previously hardcoded to http://localhost:3000/mcp) via an environment variable (MCP_SERVER_URL).

The change is implemented in packages/devtools/src/lib/mcp/index.ts, which is imported by multiple React UI components and therefore runs in the Vite browser bundle at module load time.

Confidence Score: 2/5

• Not safe to merge as-is due to a likely browser runtime error in devtools.
• The PR reads process.env.MCP_SERVER_URL in code that is bundled for the browser via Vite. Without explicit Vite define configuration or using import.meta.env, process is typically undefined in the browser, which can crash the devtools UI at startup. Fixing the env access pattern should make the change safe.
• packages/devtools/src/lib/mcp/index.ts

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[qchuchu]

Hi @ppshobi ! Thanks for contributing :)

Is it because you are using the devtools package without a skybridge mcp server ?

[ppshobi]

@qchuchu kind of, my mcp servers are at different urls, say localhost:3000/xyz/mcp and to point the devtools to the correct one , I found this option easier

[ppshobi]

@qchuchu I followed AI's suggestion to load ENV from VITE's mechanism. let me know if I am in the right direction please

[connorads]

This looks like it'd also be useful if you're working from a remote dev server (VPS) and want to look at the skybridge dev server on your machine via a tunnel. The /mcp path works fine with --use-forwarded-host but not the local dev server at / as it always points to localhost.

Update: #493 took care of it 😎