# Milestone M2 Handoff Report: Map Style Assets Integrity Test Suite

> **Agent**: `test_writer_m2`  
> **Role**: Test Writer (Quality Assurance & Test Specialist)  
> **Parent**: `orchestrator_14` (Conversation ID: `327366ba-dd05-4805-b53b-659a199b1450`)  
> **Mission**: Develop automated unit test suite `tests/unit/test_map_style_assets_integrity.py` verifying the integrity and quality of all 30 map style asset packages.  
> **Exclusive Write Boundary**: `tests/unit/test_map_style_assets_integrity.py`  

---

## 1. Observation

1. **Test Scope & Requirements (`DISPATCH.md` & `ORIGINAL_REQUEST.md` §1.3, R2)**:
   - Verify that all 30 style folders exist under `client/webapp/assets/map/styles/`.
   - Verify that each style folder contains 9 mandatory files:
     `floor.png`, `wall.png`, `path.png`, `liquid.png`, `props.png`,
     `floor_normal.png`, `wall_normal.png`, `path_normal.png`, `liquid_normal.png`.
   - Verify non-empty files with valid PNG magic header (`\x89PNG\r\n\x1a\n`).
   - Verify image dimensions: floor/path/liquid either $64\times 32$ or $128\times 64$ px; wall $128\times 128$ px; props valid dimensions.
   - Verify normal maps have Blue channel dominant ($B > 128.0$) for tangent-space lighting shaders.
   - Verify file size budgets: individual tile files $< 60\text{ KB}$, total asset folder size $< 10\text{ MB}$.

2. **Implemented Test Suite (`tests/unit/test_map_style_assets_integrity.py`)**:
   - Total lines: **284 lines** (strictly compliant with $\le 350$ lines Soft Cap, $\le 500$ lines Hard Cap).
   - Test classes:
     - `TestMapStyleDirectoryStructure`: 3 tests (root existence, 30 style subdirectories, zero unexpected dirs).
     - `TestMapStyleFileCompletenessAndMagic`: 90 tests parameterized across 30 styles (file presence, PNG magic, PIL decodability).
     - `TestMapStyleDimensions`: 90 tests parameterized across 30 styles (isometric tile dimensions, wall $128\times 128$, props sheet dimensions).
     - `TestMapStyleNormalMapsTangentSpace`: 30 tests parameterized across 30 styles (Blue channel mean $> 128.0$ on all 4 normal maps).
     - `TestMapStyleFileSizeAndBudget`: 31 tests (individual files $< 60\text{ KB}$ for 30 styles, total folder $< 10\text{ MB}$).
     - `TestMapStyleAssetAdversarialAndEdgeCases`: 5 unit tests verifying failure handling for corrupt headers, truncated files, non-existent files, sub-128 blue normal maps, and invalid tile dimensions.
   - Total test cases: **249 test cases**.

3. **Test Execution Results (`pytest tests/unit/test_map_style_assets_integrity.py -v`)**:
   - Command: `pytest tests/unit/test_map_style_assets_integrity.py -v`
   - Result: `249 passed in 1.15s` (100% pass rate).

4. **Full Map Suite Regression Verification**:
   - Command: `pytest tests/unit/test_map_styles_db.py tests/unit/test_map_styles_catalog_sync.py tests/unit/test_map_styles_adversarial.py tests/unit/test_map_style_assets_integrity.py -q`
   - Result: `335 passed in 5.96s` (0 failures, 0 regressions).

5. **Hygiene Audit (`python tools/lint/check_code_and_doc_hygiene.py --strict`)**:
   - Exited with code `0`.
   - `tests/unit/test_map_style_assets_integrity.py` has 284 lines ($\le 350$ lines soft cap) and all functions $\le 25$ lines ($\le 50$ lines cap). Zero Hard Cap violations.

---

## 2. Logic Chain

1. **Comprehensive Coverage & Contract Enforcement**:
   - `server/world/map_style_catalog.py` defines 30 canonical styles. Each style's assets are located at `client/webapp/assets/map/styles/<style_id.lower()>/`.
   - By querying `list_available_styles()`, the test dynamically inspects all 30 styles defined in the canonical catalog.
   - Each style directory must supply the 9 files required by `TileMapRenderer` and the M2 asset specification.

2. **Format & Integrity Validation**:
   - The test reads the binary prefix of each asset file and validates `b"\x89PNG\r\n\x1a\n"`. This rejects truncated, empty, or corrupt files before image processing.
   - PIL `Image.open` decodes every file to guarantee that libpng/Pillow can parse chunk headers without raising `UnidentifiedImageError`.

3. **Dimensional Contract Verification**:
   - Isometric rendering in FreeExile operates on a $2:1$ ratio: either $64\times 32$ px base or $128\times 64$ px hi-res.
   - Wall tiles require vertical extrusion ($128\times 128$ px) to prevent visual gaps in masonry.
   - The test strictly asserts `(img.width, img.height) in {(64, 32), (128, 64)}` for floor, path, liquid, and their respective normal maps, and `(128, 128)` for walls.

4. **Tangent-Space Normal Map Lighting Standards**:
   - Tangent-space lighting shaders in Apple Metal and WebGL evaluate the normal vector $N = (r, g, b) \times 2 - 1$.
   - A normal pointing outwards towards the viewer has $z > 0$, translating to blue channel $b > 0.5 \times 255 \approx 128$.
   - `compute_blue_channel_mean` extracts channel index 2 and asserts `b_mean > 128.0`. Measurements across all 30 styles yielded means between 190 and 245, confirming full compliance.

5. **Performance & Memory Budget Enforcement**:
   - Mobile memory budget limits individual textures to $< 60\text{ KB}$ and the entire suite to $< 10\text{ MB}$.
   - Measured asset suite: total size is **1.53 MB** (15.3% of budget), and maximum individual file size is **12.17 KB** (20.3% of budget), well within safety margins.

6. **Adversarial Resilience**:
   - `TestMapStyleAssetAdversarialAndEdgeCases` verifies that corrupt headers, truncated streams, missing files, low-blue normals, and invalid dimensions are immediately caught by the test logic, eliminating false positives and facade testing.

---

## 3. Caveats

- **Props Directory Subfiles**: The test validates `props.png` in the root of each style folder as required by R2. Individual subfiles under `props/<prop_id>.png` are also generated by the worker; if future systems require individual prop coordinate tests, those can be expanded in an E2E suite.
- **No Implementation Alterations**: As required by the test writer contract, no implementation code in `client/` or `server/` was modified.

---

## 4. Conclusion

The unit test suite `tests/unit/test_map_style_assets_integrity.py` is fully implemented, strictly compliant with project hygiene rules, and executes 249 assertions verifying all 30 map style asset packages. All 249 tests pass with 100% success rate in 1.15 seconds. Milestone 2 asset integrity testing is complete and ready for integration into the orchestrator pipeline.

---

## 5. Verification Method

Run the following commands to independently verify the test suite:

1. **Run Map Style Asset Integrity Unit Tests**:
   ```bash
   pytest tests/unit/test_map_style_assets_integrity.py -v
   ```
   *Expected result*: 249 passed, 0 failures.

2. **Run Full Map Suite Regression**:
   ```bash
   pytest tests/unit/test_map_styles_db.py tests/unit/test_map_styles_catalog_sync.py tests/unit/test_map_styles_adversarial.py tests/unit/test_map_style_assets_integrity.py -v
   ```
   *Expected result*: 335 passed, 0 failures.

3. **Verify Code and Document Hygiene**:
   ```bash
   python tools/lint/check_code_and_doc_hygiene.py --strict
   ```
   *Expected result*: Exit code 0, zero Hard Cap violations.