feat(#73): IMP-44 u1~u5 layout override unknown-key guard + frontend zone_geometries validation

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/phase_z2/test_build_layout_css_pr1.py

@@ -156,3 +156,109 @@ def test_top_1_bottom_2_dynamic_2d_populates_geometry():
     assert result["dynamic_cols"] is True
     assert len(result["heights_px"]) == 2   # R rows
     assert len(result["widths_px"]) == 2    # C cols
+
+
+# ────────────────────── IMP-44 u5 regression ──────────────────────
+# Regression coverage for the layout-override unknown-key guard
+# (Stage 1 root-cause #73). Asserts that foreign-preset keys are
+# dropped, structured [override-warning] is emitted, and
+# computation=user_override_geometry is NEVER reported when the
+# kept-key set is empty (no false override_applied=true).
+
+
+def test_imp44_h2_with_v2_keys_emits_warning_and_falls_through(capsys):
+    """horizontal-2 receiving vertical-2 keys (left/right) → all-unknown:
+    drop both, emit warning, fall through to dynamic dispatch.
+    computation must NOT be user_override_geometry."""
+    zones = [_zone("top", 0.6), _zone("bottom", 0.4)]
+    override = {
+        "left": {"x": 0, "y": 0, "w": 0.5, "h": 1.0},
+        "right": {"x": 0.5, "y": 0, "w": 0.5, "h": 1.0},
+    }
+    result = build_layout_css(
+        "horizontal-2", zones, override_zone_geometries=override
+    )
+    captured = capsys.readouterr()
+    assert "[override-warning]" in captured.err
+    assert "layout_preset=horizontal-2" in captured.err
+    assert "unknown_keys=['left', 'right']" in captured.err
+    assert "expected_positions=['top', 'bottom']" in captured.err
+    # All-unknown → no override applied (no silent fallback).
+    assert result["computation"] != "user_override_geometry"
+    raw = result.get("raw_zone_layout") or {}
+    if isinstance(raw, dict):
+        assert raw.get("override_applied") is not True
+
+
+def test_imp44_v2_with_h2_keys_emits_warning_and_falls_through(capsys):
+    """vertical-2 receiving horizontal-2 keys (top/bottom) → all-unknown:
+    drop both, emit warning, fall through to dynamic dispatch.
+    computation must NOT be user_override_geometry."""
+    zones = [_zone("left", 0.5), _zone("right", 0.5)]
+    override = {
+        "top": {"x": 0, "y": 0, "w": 1.0, "h": 0.3},
+        "bottom": {"x": 0, "y": 0.3, "w": 1.0, "h": 0.7},
+    }
+    result = build_layout_css(
+        "vertical-2", zones, override_zone_geometries=override
+    )
+    captured = capsys.readouterr()
+    assert "[override-warning]" in captured.err
+    assert "layout_preset=vertical-2" in captured.err
+    assert "unknown_keys=['bottom', 'top']" in captured.err
+    assert "expected_positions=['left', 'right']" in captured.err
+    assert result["computation"] != "user_override_geometry"
+    raw = result.get("raw_zone_layout") or {}
+    if isinstance(raw, dict):
+        assert raw.get("override_applied") is not True
+
+
+def test_imp44_partial_mix_keeps_known_drops_unknown(capsys):
+    """horizontal-2 receiving {top (known), left (unknown)}: keep top,
+    drop left, emit warning naming only 'left'. override_applied=True
+    must hold and the source must contain only the kept key."""
+    zones = [_zone("top", 0.6), _zone("bottom", 0.4)]
+    override = {
+        "top": {"x": 0, "y": 0, "w": 1.0, "h": 0.3},
+        "left": {"x": 0, "y": 0, "w": 0.5, "h": 1.0},
+    }
+    result = build_layout_css(
+        "horizontal-2", zones, override_zone_geometries=override
+    )
+    captured = capsys.readouterr()
+    assert "[override-warning]" in captured.err
+    assert "unknown_keys=['left']" in captured.err
+    # Known key applied → user_override_geometry computation.
+    assert result["computation"] == "user_override_geometry"
+    raw = result["raw_zone_layout"]
+    assert raw["override_applied"] is True
+    assert set(raw["source"].keys()) == {"top"}
+    # Sanity: top ratio (0.3) drives heights_px[0] < heights_px[1].
+    assert result["heights_px"][0] < result["heights_px"][1]
+
+
+def test_imp44_2d_preset_with_h2_keys_emits_warning_and_falls_through(capsys):
+    """2-D preset (top-1-bottom-2) receiving horizontal-2 keys
+    (top/bottom): all-unknown vs T positions
+    {top, bottom-left, bottom-right} → drop all, emit warning,
+    fall through to 2-D dynamic dispatch."""
+    zones = [
+        _zone("top", 0.5),
+        _zone("bottom-left", 0.25),
+        _zone("bottom-right", 0.25),
+    ]
+    override = {
+        "bottom": {"x": 0, "y": 0.3, "w": 1.0, "h": 0.7},
+    }
+    result = build_layout_css(
+        "top-1-bottom-2", zones, override_zone_geometries=override
+    )
+    captured = capsys.readouterr()
+    assert "[override-warning]" in captured.err
+    assert "layout_preset=top-1-bottom-2" in captured.err
+    assert "unknown_keys=['bottom']" in captured.err
+    # All-unknown → 2-D dynamic fallback (not user_override_geometry).
+    assert result["computation"] == "2d_dynamic_aggregated"
+    raw = result.get("raw_zone_layout") or {}
+    if isinstance(raw, dict):
+        assert raw.get("override_applied") is not True