v0.2.0 — Cross-process evidence and no-progress validation

v0.2.0 — Cross-process evidence and no-progress validation

v0.2.0 turns the lab's evidence method into a bounded workflow that another
engineer can run without a GPU. It adds collect, offline verify, and an
installed replay command while preserving undetermined as a valid outcome
when the evidence cannot support a stronger claim.

Five-minute replay

python -m pip install .  # installs distribution vllm-runtime-dfx-lab
vllm-dfx replay results/vllm-zmq-backpressure-stage1-r3-20260916

The replay verifies the frozen #53859 four-cell evidence, file identities,
health-green no-progress claim, blocking-stack claim, fix-arm progress, and the
measured four-batch event-loss trade-off. It does not rerun the GPU experiment.

Delivered in v0.2.0

• bounded collect bundles with operator-supplied PID identity, endpoint
  privacy, and always-closed observation windows;
• independent server-counter and opt-in client-request progress producers;
• explicit demand evidence and producer-conflict reporting;
• five closed verdicts with deterministic precedence: process_missing,
  health_lost, progress_observed, alive_health_ok_no_progress, and
  undetermined;
• offline, fail-closed verdict recomputation from closed-shape JSON;
• typed optional py-spy availability and producer identity while raw stacks
  remain private and non-decisional;
• a machine-checked registry that classifies every public leaf field as
  decisional or explicitly non-decisional;
• a compatibility projection that reports evidence missing from the legacy
  #53859 result instead of inventing native v0.2 observations; and
• vllm-dfx replay as the installed no-GPU entry point.

Evidence-backed results

• Lab-originated PyTorch #196968
  established that a missing Flight Recorder dump did not mean a missing rank;
  PR #197232 proposes the C++
  fix. Both were open on 2026-09-21.
• The lab independently validated reported
  vLLM #53859 and proposed
  PR #53883: /health
  remained 2xx while EngineCore token progress stopped under deterministic
  event-queue backpressure. This was not a lab-originated bug.
• Lab-originated PyTorch #196996
  reduced an apparent distributed hang to a single-GPU FSDP2 mixed-gradient
  dtype correctness failure.

Publication boundary

The complete #196968 case study is not part of this release. Its publication
gate requires an explicit upstream outcome for #197232: merge, explicit design
acceptance with another landing path, or explicit rejection/supersession with a
documented reason. An open PR, passing CI, bot labels, or silence is not an
upstream outcome.

#49869 is an independent upstream contribution and is not a lab discovery.
#52178 is a separately found lifecycle bug for which the lab supplied
process-level validation.

Known boundaries

This remains an alpha research tool, not a production monitor, automatic
process/rank discovery system, general cross-rank or cross-host joiner,
native-state classifier, remediation controller, or automatic root-cause
classifier. Stack availability and producer implementation cannot change a
verdict. Endpoint-only flat progress remains undetermined because repeated
2xx responses do not establish process liveness.

Immutable release references

• v0.2.0 source tree
• v0.2 collect/verify contract
• Field-role audit
• Published #53859 replay evidence

Release artifact SHA-256 values and clean-install transcripts are published
alongside the release assets built from the exact tagged commit.