**Overall Verdict:** Accept — The task is complete, objectively verifiable, and end-to-end reachable; only a routine runtime-wrapper path correction is advisable.

**Completeness Check:**
- Instruction: Complete — The PDE, stencil, manufactured solution, studies, solver interface, output schemas, constraints, and completion criteria are fully specified.
- Inputs: Complete — The specification and pinned runtime manifests are readable and sufficient; solver-visible inputs are clearly separated from evaluator-only references.
- Toolchain: Complete — Python 3.11–3.13 with pinned open-source NumPy and SciPy dependencies provides a reproducible Linux toolchain, although the wrapper’s relative project path does not match the declared runtime-input location.
- Reference output: Complete — The solver source, 26-array NPZ artifact, and JSON sidecar are structurally consistent. Independent numeric checks reproduced the stated orders, amplification factors, stability behavior, and artifact accuracy.
- Rubric: Complete — The evaluator defines objective tiered scoring, schema and provenance checks, independent scheme fidelity tests, convergence thresholds, stability validation, artifact regeneration, and explicit failure behavior.

**File and Task Reachability:**
Attachment classification: `reachable`. All nine manifested attachments were inspected: `problem_spec.md`, `python.sh`, `pyproject.toml`, `uv.lock`, `box_solver.py`, `reference_arrays.npz`, `results.json`, `EVALUATION.md`, and `grade.py`. Their byte counts match the manifest. Text files are readable ASCII or UTF-8; the NPZ is an unencrypted single-part archive containing 26 flat, non-object NumPy arrays with expected scalar, 5-, 7-, and 256-element shapes. Only the first entries of the three EOC arrays contain intended NaNs. No attachment content remains unreviewed.

Task classification: `reachable`. A contributor can use the supplied specification and pinned open-source dependencies on one ordinary Linux machine, produce the three required outputs, and be evaluated through independent solver fidelity, regeneration, convergence, stability, and artifact checks. Reference answers and evaluator-selected meshes are confined to reference/evaluator attachments rather than the declared solver-visible inputs. Submitted executables were inspected statically and not run; independent non-executing calculations validated the principal numerical contracts. The wrapper path issue has a deterministic local correction and does not block the available manifest-based toolchain.

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. There is no affirmative evidence of AI-fabricated core material, a public benchmark with a retrievable protected answer, or a deliberately injected defect fixture. Public identifiability could not be independently searched under the permitted review boundary.

**Recommended Changes:**
The numerical specification, reference artifacts, and evaluator are coherent and unusually thorough; no material contributor revision is required. As routine cleanup, update `python.sh` to resolve the runtime project at the declared input-runtime directory, or stage a matching directory alias, and clarify that temporary virtual-environment creation is permitted despite the output-only task-file rule.