**Overall Verdict:** Strong Accept — The submission is complete, internally consistent, professionally representative, safely reachable, and backed by objective evaluation with validated positive and negative cases.

**Completeness Check:**
- Instruction: Complete — The source order, channel correction, Lo/Ro coefficients, LFE exclusion, whole-program loudness targets, and deliverable formats are unambiguous.
- Inputs: Complete — The specification, mix memo, and three distinct 5.1 PCM sources are readable and consistent with their declared roles.
- Toolchain: Complete — FFmpeg/FFprobe with standard filters and libmp3lame provide a legally obtainable, single-machine workflow.
- Reference output: Complete — The stereo 24-bit WAV and 192 kbps MP3 are readable, match logged hashes, and have compatible format, duration, routing, and loudness evidence.
- Rubric: Complete — The static evaluator defines deterministic format, loudness, routing, center attenuation, surround isolation, LFE, and MP3-content checks, with hard gates and weighted partial scoring.

**File and Task Reachability:**
The attachment set is `reachable`, and the end-to-end task is `reachable`. Both ZIP attachments matched their manifested sizes, passed container integrity checks, and contained only regular, unencrypted files with safe relative paths and modest expansion. Inspected content included `spec_sheet.md`, `mix_memo.txt`, all three source WAVs, both reference deliverables, both naive deliverables, `evaluate.py`, `task_card.json`, `build_log.txt`, `naive_log.txt`, and `selftest_review_log.txt`; no attachment content remained unreviewed. Static media inspection confirmed 5.1/48 kHz/24-bit source WAVs, a stereo/48 kHz/24-bit reference WAV without full-scale samples, and fixed-size MPEG-1 Layer III 192 kbps/48 kHz stereo reference frames. The submitted hashes matched the build record. Direct FFmpeg decoding and evaluator rerunning were unavailable in the review environment, but this is a reviewer-tooling limitation; media structures, evaluator logic, logged measurements, and positive and targeted-negative results were independently cross-checked. Solver-visible inputs and hidden reference/evaluation assets are cleanly separated. The completion path is source correction, Lo/Ro downmix, hard concatenation, two-pass whole-program loudness conformance, WAV mastering, and MP3 derivation; evaluation directly covers the required outputs. 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 unusually thorough routing evidence, reproducible reference artifacts, and targeted negative tests. No changes are required.