**Overall Verdict:** Strong Accept — The submission is complete, internally consistent, professionally challenging, objectively verifiable, and fully reachable with the declared open-source toolchain.

**Completeness Check:**
- Instruction: Complete — The specification precisely defines the source master, target grid, reprojection method, strict zonal membership, statistics formatting, contour construction, and deliverable paths.
- Inputs: Complete — All three GeoTIFFs have the declared CRS, resolution, nodata, and dimensions; the Shapefile and GeoJSON contain the same three named polygons with identical coordinates.
- Toolchain: Complete — Python, Rasterio, PyProj, Shapely, and NumPy provide a legally obtainable Linux workflow with modest single-machine requirements.
- Reference output: Complete — The reference raster has the required 200 × 200 EPSG:4326 grid. Independent recomputation reproduced all three CSV rows within six-decimal rounding and verified all 2,236 contour vertices and 2,226 local segments.
- Rubric: Complete — Deterministic hard gates, weighted partial credit, representation tolerances, malformed-output handling, and targeted negative cases distinguish correct, partial, and invalid submissions.

**File and Task Reachability:**
Attachment classification: reachable. Task classification: reachable. Both `04_upload_inputs.zip` and `04_upload_reference.zip` matched their manifest sizes, were unencrypted, traversal-free, CRC-valid, and safely inspected. Inspected content included the three DEMs, `spec_sheet.md`, all Shapefile components, `zones.geojson`, the three reference outputs, evaluator sources, task card, naive outputs, and all supplied logs. No attachment content remained unreviewed. The review environment lacked Python/GDAL execution tooling, so the evaluator was reviewed statically; independent structured parsing still verified raster metadata and samples, exact zonal results, and complete contour geometry. Solver inputs and protected reference/evaluation assets are separated into distinct archives. The end-to-end path is clear: reproject the UTM master to the mandated grid, compute exact-membership statistics, generate lattice-interpolated contours, and evaluate the three outputs deterministically against the packaged references and delivered raster. 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 already provides coherent inputs, precise requirements, validated references, and robust evaluation coverage. No changes are required.