[Bug]: Static assets return 404 when APP_ROOT_PATH is configured

[ESnark]

🐞 Bug Summary

Static assets (CSS, JS) fail to load with 404 errors when MCP Gateway is deployed behind a reverse proxy with a custom base path configured via APP_ROOT_PATH.

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🧩 Affected Component

Select the area of the project impacted:

• mcpgateway - API
• mcpgateway - UI (admin panel)
• mcpgateway.wrapper - stdio wrapper
• Federation or Transports
• CLI, Makefiles, or shell scripts
• Container setup (Docker/Podman/Compose)
• Other (explain below)

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🔁 Steps to Reproduce

1. Set environment variable APP_ROOT_PATH=/gateway (or any custom path)
2. Access the Admin UI at https://example.com/gateway/admin
3. Observe browser DevTools Network tab showing 404 errors for:
   • /static/admin.css (should be /gateway/static/admin.css)
   • /static/admin.js (should be /gateway/static/admin.js)

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🤔 Expected Behavior

Static assets should be served from the correct path when APP_ROOT_PATH is configured. The application should mount static files at {APP_ROOT_PATH}/static instead of always using /static.

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📓 Logs / Error Output

Browser Console:
GET https://example.com/static/admin.css 404 (Not Found)
GET https://example.com/static/admin.js 404 (Not Found)

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🧠 Environment Info

Key	Value
Version or commit	main@c0ae3d1
Runtime	Python 3.11, Gunicorn
Platform / OS	macOS
Container	Docker

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🧩 Additional Context (optional)

#858

[MohanLaksh]

PR #858 fixes this issue