pub fn validate_config_edit(key: &str, value: &str) -> Result<(), String>Expand description
Check a key = value edit before it is written (the /settings modal).
Runs the real parser over the config file as it would look after
write_config_value and returns Err with the parser’s own messages
for any problem the edit introduces — invalid values, and cross-key
rules such as context_management threshold ordering, subagent
concurrency vs total, or memory.default_mode without operator consent.
Problems already present before the edit are not blamed on it.