Hermes and everything it launches (browser profiles, PTY probes, skill scripts,
tempfile defaults in delegated code) wrote to the system temp dir, which is a
RAM-backed tmpfs on most Linux hosts and containers and fills under agent load.
- hermes_constants.get_scratch_dir(): HERMES_HOME/cache/scratch (0700), entries
older than 72h pruned once per process / once per hour across processes.
- apply_scratch_tmp_env(env) / export_scratch_tmp_env(): TMPDIR/TMP/TEMP point at
the scratch dir when the user or OS has not set them; a value Hermes itself
exported (== HERMES_SCRATCH_DIR) is re-derived for a re-homed process or a
child served under another profile, so profiles never share scratch.
- hermes_bootstrap runs the export on import (every entry point); hermes_cli.main
re-runs it after --profile resolution; the subprocess HOME contract
(apply_subprocess_home_env) and the routed-home rewrites in code_execution_env
and served_profile_child_env apply it to child envs.
- The runtime-environment prompt block names the scratch dir so the model stops
reaching for the system temp dir by reflex; hermes doctor reports the dir, its
size and whether a user TMPDIR overrides it.
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