**Overall Verdict:** Strong Accept — The task is complete, technically rigorous, objectively gradable, and feasible on the declared GPU environment with coherent input and reference evidence.

**Completeness Check:**
- Instruction: Complete — The defect, required behavior, constraints, exact deliverables, and success conditions are explicit.
- Inputs: Complete — Both 125.6-second, 1280×720 AVC videos are valid; their encoded video payloads are identical, while only the with-audio variant contains an AAC track. The probe source matches the described A/B workflow.
- Toolchain: Complete — Exact package versions, operating system, GPU capacity, model, launch command, and permitted patch target are specified.
- Reference output: Complete — The reference contains a valid three-file vLLM-only unified patch, schema-valid probe results, and a server log showing successful startup and four HTTP 200 inference requests without a post-startup traceback. The result has a 1,635-token delta, `NO_SPEECH` for silent video, and all six specified commentary keywords for audio video.
- Rubric: Complete — Automated checks independently cover patch applicability, startup, audio delivery, per-request kwargs, cache isolation, graceful degradation, engine survival, and artifact integrity.

**File and Task Reachability:**
The attachment set is `reachable`, and the end-to-end task is `reachable`. Both `reference_output.zip` and `input_materials.zip` were fully inspected and were readable, unencrypted, CRC-clean ZIP containers with safe relative entries and modest expansion. Substantive members inspected were `fix.patch`, `probe_ab_result.json`, `server.log`, `probe_audio_ab.py`, `test_withaudio.mp4`, and `test_noaudio.mp4`. Only non-substantive AppleDouble metadata sidecars were not content-decoded. The reference archive is separately designated as reference evidence and should remain evaluator-only. The review environment lacked the pristine vLLM package tree and required GPU/model runtime, so clean application and live serving were not independently rerun; patch syntax and scope were validated statically. Completion and evaluation remain direct: patch the pristine 0.20.2 tree, launch the declared server, query health, execute the A/B and per-request tests in the required order, verify continued health, and validate the three output artifacts. The probe’s model-suffixed result filename requires only deterministic output-location normalization. License keys, accounts, tokens, and other credentials are not required from the contributor. Confidential, proprietary, or internal material may be evaluated as submitted evidence without requiring additional disclosure.

**Special Screening:**
None

**Recommended Changes:**
The submission provides representative inputs, a credible reference implementation, live-run evidence, and unusually precise regression criteria. No changes are required.