A misspelled or unknown config key was accepted silently, so a typo in exclude backed up everything it meant to leave out. Loading now refuses a key that no setting has, at any depth, naming its dotted path and, when it is in the file, its line; keys brought in by ${...} references are checked too. config set refuses an unknown key. A top-level env: section stays accepted, since the config library uses it. Anchors that contain themselves fail with an error.
Model: opus-5-5
