002: Scratch copy validation for config edits

Context Researchers use the web-based Studio to edit project configuration (YAML files). Misconfigured files can cause the application to crash or behave incorrectly for active participants.

Decision Every change made in the Studio is validated against a temporary scratch copy of the whole project. Only if the project loads successfully without errors are the changes committed to the live project files.

Alternatives rejected

• Immediate write with try/catch: Leaves the live project in a broken state if the write introduces a syntax error, potentially disrupting live studies.
• Client-side only validation: Difficult to perfectly replicate all server-side logic in JS, leading to edge cases where bad configs still make it through.

Costs accepted

• Increased disk IO and CPU overhead on every edit in the Studio, since we are doing full copies of the project folder (minus history) to a temp directory.
• Slower save times. This is acceptable since configuration edits are infrequent compared to participant interactions.