create specific firmware online

As mentioned in another chat, I'm just restarting a project to create specific firmware for Espruino.
It's in early state and will take some time.
Create specific firmware means

• you only need a browser, no development tools on your computer
  
• select board
  
• set/unset definitions like USE_BLUETOOTH or USE_GRAPHICS
  
• remove functions, you don't need. Like eval to give an example
  
• add JS modules to firmware, Gordon already does this for some boards
  
• add your own source files (c-filesand h-files)
  
  

@Gordon already mentioned, that support of c-files opens a door for security issues.
AFAIK, these are mainly security issues for the server. One example is the use of
#include "/usr/passwd" in C-source
Ideas to bypass this problems are

• build my own scanner to recognize
  
• search the internet for scanners
  
• load sources only from "secure github sites"
  
• remove the option for adding c sources, in my eyes the worst option
  
  

Please give comments/feedback/experience
Hopefully somebody has some knowledge around this.