added fresnel zone

api/app/core/propagation.py

@@ -65,5 +65,5 @@ def manual_link_budget(
         rx_power_dbm=rx_power,
         fade_margin_db=margin,
         fresnel_clear=fresnel_clear,
-        link_viable=margin > 0 and fresnel_clear,
+        link_viable=margin > 0,
     )

api/app/models/link.py

@@ -27,6 +27,7 @@ class LinkBudgetResponse(BaseModel):
     rx_power_dbm: float
     fade_margin_db: float
     fresnel_clear: bool
+    fresnel_quality: Literal["clear", "partial", "blocked"]
     link_viable: bool
     los_clear: bool
     geometric_los: bool

api/app/services/link.py

@@ -68,6 +68,7 @@ def link_budget(request: LinkBudgetRequest, db: Session | None = None) -> LinkBu
     ]
     return LinkBudgetResponse(
         **budget.__dict__,
+        fresnel_quality=_fresnel_quality(los_result.los_clear, los_result.geometric_los),
         los_clear=los_result.los_clear,
         geometric_los=los_result.geometric_los,
         first_fresnel_clearance_pct=los_result.first_fresnel_clearance_pct,
@@ -85,6 +86,14 @@ def link_budget(request: LinkBudgetRequest, db: Session | None = None) -> LinkBu
     )
 
 
+def _fresnel_quality(los_clear: bool, geometric_los: bool) -> str:
+    if los_clear:
+        return "clear"
+    if geometric_los:
+        return "partial"
+    return "blocked"
+
+
 def _convert_obstruction(sample: LosSample | None) -> Obstruction | None:
     if sample is None:
         return None

api/tests/test_api.py

@@ -123,4 +123,5 @@ def test_manual_link_budget_endpoint() -> None:
     data = response.json()
     assert data["fspl_db"] > 0
     assert "link_viable" in data
+    assert data["fresnel_quality"] in {"clear", "partial", "blocked"}
     assert "data_sources" in data

api/tests/test_vegetation_integration.py

@@ -97,7 +97,54 @@ def test_link_budget_includes_diffraction_loss(monkeypatch) -> None:
     assert isclose(result.total_loss_db, result.fspl_db + result.diffraction_db)
     assert result.fresnel_clear is False
     assert result.los_clear is False
+    assert result.fresnel_quality == "blocked"
     assert result.geometric_los is False
     assert result.fresnel_violations_count > 0
     assert result.geometric_obstructions_count > 0
     assert result.worst_obstruction is not None
+
+
+def test_link_viable_depends_on_margin_not_fresnel_quality(monkeypatch) -> None:
+    monkeypatch.setattr(link_service, "vegetation_loss_along", lambda *args, **kwargs: 0.0)
+
+    def fake_profile(points, *args, **kwargs):
+        midpoint = len(points) // 2
+        return SurfaceProfile(
+            distance_m=points[-1].distance_m,
+            samples=[
+                SurfaceSample(
+                    i=index,
+                    lat=point.lat,
+                    lon=point.lon,
+                    distance_m=point.distance_m,
+                    ground_m=20.0 if index == midpoint else 0.0,
+                    building_m=0,
+                    canopy_m=0,
+                    surface_m=20.0 if index == midpoint else 0.0,
+                )
+                for index, point in enumerate(points)
+            ],
+        )
+
+    monkeypatch.setattr(link_service, "surface_profile_from_points", fake_profile)
+    request = LinkBudgetRequest(
+        tx=LinkTx(lat=60.17, lon=24.94, height_agl=0, power_dbm=70, gain_dbi=8),
+        rx=LinkRx(
+            lat=60.25,
+            lon=25.10,
+            height_agl=0,
+            gain_dbi=2,
+            sensitivity_dbm=-120,
+        ),
+        frequency_mhz=433,
+        model="manual",
+        include_buildings=False,
+        include_vegetation=False,
+    )
+
+    result = link_service.link_budget(request)
+
+    assert result.fade_margin_db > 0
+    assert result.fresnel_quality == "blocked"
+    assert result.fresnel_clear is False
+    assert result.link_viable is True