Live test found the gap: a nonexistent model fails in
thread/start, host.py exits non-zero without JSON, so the
executor result has host_status=None and the worker never
fell back (task failed, no worker_fallback audit). When
host_status is absent, worker now extracts an explicit signal
from stdout/stderr/runner error: 404/429/5xx codes, or
'model not found' style text (counted as 404). Generic
failures with no explicit code still do not fall back, and
401 in stderr still never falls back. Tests: fallback 9 pass,
cloud 333 pass, host 27 pass.
host
6cee452750