Fixes all actionable items from the second review:

Bug fixes:
- #1: Change returncode=4 → returncode=2 in pytest_configure exit
  (4 is reserved by pytest for EXIT_NOTESTSCOLLECTED)
- #2: Add comment clarifying HF_HUB_OFFLINE double-clear is safe
  (already in _MODELS_DIR_ENV_KEYS; loop correctly restores original)

Test quality:
- #7: Add missing assertions to test_apply_hf_home_layout
  (HF_HUB_OFFLINE, TRANSFORMERS_OFFLINE, DYNAMO_MODELS_DIR, TRANSFORMERS_CACHE)
- #8: Use monkeypatch in tests 3 & 4 for proper env isolation
  (prevents pre-existing env vars from leaking on test failure)

Design / correctness:
- #3: Fix _models_dir_env docstring ("exactly once" → "once per worker")
- #4: Add comment noting TRANSFORMERS_CACHE deprecation
- #5: Update --models-dir help text and docs to reflect both supported
  layouts (bare HF_HUB_CACHE and HF_HOME), not just bare
- #10: Restore pytest.skip() in download_lora() (test-only infra);
  remove now-redundant guard from minio_lora_service fixture
- #11: Raise hub/ detection log to WARNING with guidance
- #12: Replace shutil.rmtree(ignore_errors=True) with try/except
  so cleanup failures are logged rather than silently swallowed

Not addressed: #6 (keep gpu_0 per project marker policy), #9 (pytester
test deferred — complex due to conftest dependencies, low severity)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Signed-off-by: rrubin <rrubin@nvidia.com>

…auge reset (review ai-dynamo#12/ai-dynamo#13/ai-dynamo#19)

Hot-path quality fixes — none change a scaling decision.

ai-dynamo#12 pipeline durations use Clock.monotonic(), not Clock.now()
  Clock's contract reserves now() for wall-clock timestamps and monotonic()
  for duration measurement. Six duration sites (predict latency, fan-out
  call latency, whole-tick duration) used now(); under WallClock a backward
  NTP step mid-tick distorted the latency/duration histograms. Switched all
  six to monotonic(). VirtualClock.monotonic() is synced to trace time in
  replay, so replay/test behavior is unchanged.

ai-dynamo#13 ProposeResult derives result_kind + enforces the oneof
  ProposeResult carries the same accept/override/reject oneof as the stage
  responses but, unlike them, had no model_post_init — so building it the
  natural way (override=...) left result_kind='' and the proto round-trip
  came back 'override', breaking round-trip equality; a two-payload oneof
  violation also went unchecked. Extracted the derive+validate logic into a
  shared _derive_result_kind() helper used by both _StageOneofResponse and
  ProposeResult. +round-trip test (derive + oneof-violation reject).

ai-dynamo#19 override_active gauge reset covers errored plugins
  _emit_override_active reset the gauge only for plugins in plugin_results;
  a plugin whose call raised is absent from that list, so a 1 it set on a
  prior tick lingered. Now reset every ATTEMPTED plugin id (triggered +
  inherited) before setting the contributors.

828 planner tests pass (+1 round-trip test).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>