## [Claude #3] Stage 6 — Verification Round #3

### Re-read issue
Scope = `build_layout_css` 분기 확장 to **top-1-bottom-2 / top-2-bottom-1 / left-1-right-2 / left-2-right-1 / grid-2x2** beyond the existing horizontal-2 / vertical-2 dynamic paths.
Guardrail = Kei `build_containers_type_b` (page_structure) 회귀 X + zone-level ratio 변경 시 Step 8 trace 설명 가능.

### Full pytest
```
python -m pytest -q tests
89 passed in 6.85s
```
Phase Z2 subset: 47/47 passed.

### AS-IS (HEAD = 201099e — unchanged since Round #2)

**Git state:**
```
201099e feat(IMP-09): PR 1 — col-axis solver + per-zone geometry mapper + retry gate
```
`git diff HEAD -- src/space_allocator.py src/phase_z2_pipeline.py` → empty (no in-flight edits since Round #2).

**Static evidence — dispatch is still rows / cols only** (src/phase_z2_pipeline.py:1214–1221):
```python
# ── Dynamic branch — topology dispatch (PR 1: rows / cols only) ──
if topology == "rows":
    return _build_rows_dynamic(preset, zones_data, gap)
if topology == "cols":
    return _build_cols_dynamic(preset, zones_data, gap)
# PR 2 will dispatch T / inverted-T / side-T-{left,right} / 2x2 here.
# PR 3 will dispatch single here.
return _build_fr_default(preset)
```

Override path (src/phase_z2_pipeline.py:1205–1212) is still warn-and-fallthrough for non rows/cols presets (PR 1 lock — PR 2 promotes to strict ValueError).

**Runtime probe** — `build_layout_css(preset, zones)` with each zone carrying `{content_weight: 1.0, min_height_px: 100}` for every zone-id present in the 5 + single topologies:

| Preset | dynamic_rows | dynamic_cols | computation |
|---|---|---|---|
| `top-1-bottom-2` | False | False | `fr_default_from_preset` |
| `top-2-bottom-1` | False | False | `fr_default_from_preset` |
| `left-1-right-2` | False | False | `fr_default_from_preset` |
| `left-2-right-1` | False | False | `fr_default_from_preset` |
| `grid-2x2` | False | False | `fr_default_from_preset` |
| `single` | False | False | `fr_default_from_preset` |

**Test evidence — PR 1 tests still explicitly assert the unfinished state** (tests/phase_z2/test_build_layout_css_pr1.py:145–154):
```python
"""T-shape (top-1-bottom-2) falls through to fr_default in PR 1 …"""
result = build_layout_css("top-1-bottom-2", zones)
assert result["computation"] == "fr_default_from_preset"
```
This is a **PR 1 lock-in** assertion. Closing B-4 requires updating it when PR 2 lands.

### TO-BE (issue scope target)
All 5 listed presets must be dynamic; currently 0/5 are. PR 1 (HEAD) is the *foundation lock* — it delivers the col-axis solver, unified per-zone geometry mapper, length-locked widths/widths_ratios/dynamic_cols on every return path, the retry gate (with `retry_skipped_reason`), and `zone_widths_px_planned` / `zone_col_ratios_planned` Step 8 trace fields. PR 2 (T / inverted-T / side-T-{left,right} / 2x2) + PR 3 (single) remain outstanding per code comments at lines 1219–1220.

### Guardrail check
`build_containers_type_b` / `page_structure` paths untouched by PR 1; static grep on `src/` shows them in space_allocator.py / block_assembler*.py / kei_client.py / pipeline.py / validators.py / fit_verifier.py / content_verifier.py / step_visualizer.py / html_generator.py / pipeline_context.py / block_reference.py — `git diff HEAD -- src/phase_z2_pipeline.py src/space_allocator.py` is empty so no regression risk introduced since 201099e.

### Gaps vs Close

| Axis | Issue requirement | Current state | Gap |
|---|---|---|---|
| top-1-bottom-2 dynamic | required | fr_default fallthrough | NOT MET |
| top-2-bottom-1 dynamic | required | fr_default fallthrough | NOT MET |
| left-1-right-2 dynamic | required | fr_default fallthrough | NOT MET |
| left-2-right-1 dynamic | required | fr_default fallthrough | NOT MET |
| grid-2x2 dynamic | required | fr_default fallthrough | NOT MET |
| Kei `build_containers_type_b` 회귀 X | required | satisfied (untouched) | OK |
| Step 8 trace ratio fields | required | landed (`zone_widths_px_planned`, `zone_col_ratios_planned`, per-zone variants) | OK |

5 of 5 scope-axes still NOT MET. Foundation + guardrail axes are MET, but B-4 closure needs PR 2 (T / inverted-T / side-T-{left,right} / 2x2 dispatch). Three independent rounds (Claude #1+#2+#3, Codex #1+#2) agree.

### Verdict
NOT VERIFIED for close. Issue must remain open pending PR 2 (the 5 listed presets) and PR 3 (single).

=== EVIDENCE ===
Commands run:
- `git log --oneline -5` → HEAD = 201099e (PR 1)
- `git status --short` → no in-flight edits to src/phase_z2_pipeline.py or src/space_allocator.py
- `git diff HEAD -- src/space_allocator.py src/phase_z2_pipeline.py` → empty
- `python -m pytest -q tests` → 89 passed in 6.85s
- Runtime probe: `python -c "from src.phase_z2_pipeline import build_layout_css; ..."` for top-1-bottom-2 / top-2-bottom-1 / left-1-right-2 / left-2-right-1 / grid-2x2 / single

Files checked:
- D:\ad-hoc\kei\design_agent\src\phase_z2_pipeline.py (lines 1180–1221: override path + dynamic dispatch)
- D:\ad-hoc\kei\design_agent\tests\phase_z2\test_build_layout_css_pr1.py (PR 1 lock-in assertion)
- D:\ad-hoc\kei\design_agent\src\space_allocator.py (no diff)

Verified facts:
- 5 of 5 listed presets return `computation=fr_default_from_preset` with `dynamic_rows=False, dynamic_cols=False`
- Single preset also returns fr_default (PR 3 scope per inline comment)
- horizontal-2 / vertical-2 dynamic paths preserved by PR 1 (covered by tests/phase_z2/test_build_layout_css_pr1.py with full fixtures)
- `build_containers_type_b` / `page_structure` paths untouched by PR 1
- Step 8 trace fields landed on PR 1 (`zone_widths_px_planned`, `zone_col_ratios_planned`, `zone_width_px_planned`, `zone_col_ratio_planned`)

FINAL_CONSENSUS: NO