Concurrent ACP sessions run on a shared ThreadPoolExecutor (max_workers=4).
Each _run_agent mutated the process-global os.environ["HERMES_INTERACTIVE"]
and restored it in finally, so one session's restore could clobber another's
set mid-run — dropping the second session onto the non-interactive
auto-approve path, executing a dangerous command without the approval
callback firing (GHSA-96vc-wcxf-jjff).
Replace the env-var flag with a thread/task-local contextvar in
tools.approval. The two HERMES_INTERACTIVE read sites in approval.py now go
through _is_interactive_cli() (contextvar-first, env fallback for legacy
single-threaded CLI callers). The ACP executor sets the contextvar instead
of os.environ; the existing contextvars.copy_context() wrapper isolates each
session's write.
Co-authored-by: Hermes Agent <127238744+teknium1@users.noreply.github.com>
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