Eval probes wrote fixtures, receipts and evidence to hard-coded /tmp paths and
two live A/B tasks literally instructed the model to work in /tmp. They now
derive locations from tempfile.gettempdir() / os.tmpdir() (env overrides kept),
usage examples use relative output names, and the desktop e2e screenshot dirs,
perf scripts and the short-session repro fixture stop naming /tmp. Also adds
the explicit encoding= the windows-footgun check wants in the touched files.
