diff --git a/apps/planner/app/components/PlannerMap.tsx b/apps/planner/app/components/PlannerMap.tsx
index d8d3499..0ec1aef 100644
--- a/apps/planner/app/components/PlannerMap.tsx
+++ b/apps/planner/app/components/PlannerMap.tsx
@@ -170,8 +170,15 @@ function CursorTracker({ awareness }: { awareness: YjsState["awareness"] }) {
 }
 
 function NoGoAreaButton({ active, onClick }: { active: boolean; onClick: () => void }) {
+  const ref = useRef<HTMLDivElement>(null);
+
+  // Prevent clicks from reaching the Leaflet map (same as built-in controls)
+  useEffect(() => {
+    if (ref.current) L.DomEvent.disableClickPropagation(ref.current);
+  }, []);
+
   return (
-    <div className="leaflet-top leaflet-left" style={{ marginTop: 80 }}>
+    <div ref={ref} className="leaflet-top leaflet-left" style={{ marginTop: 80 }}>
       <div className="leaflet-control leaflet-bar">
         <a
           href="#"
diff --git a/apps/planner/app/lib/brouter.ts b/apps/planner/app/lib/brouter.ts
index b772c3c..4e0bfd6 100644
--- a/apps/planner/app/lib/brouter.ts
+++ b/apps/planner/app/lib/brouter.ts
@@ -52,7 +52,7 @@ export async function computeRoute(request: RouteRequest): Promise<EnrichedRoute
         format,
         tiledesc: "true",
       });
-      if (nogoParam) params.set("nogos", nogoParam);
+      if (nogoParam) params.set("polygons", nogoParam);
       return fetchSegment(`${BROUTER_URL}/brouter?${params}`);
     }),
   );
@@ -180,40 +180,19 @@ function extractSurfacesFromMessages(properties: Record<string, unknown>): Map<n
 }
 
 /**
- * Convert no-go area polygons to BRouter's `nogos` parameter format.
- * BRouter accepts `lon,lat,radius` per no-go circle, separated by `|`.
- * We approximate each polygon as a circle: centroid + max distance to any vertex.
+ * Convert no-go area polygons to BRouter's `polygons` parameter format.
+ * Format: lon1,lat1,lon2,lat2,...,lonN,latN separated by `|` per polygon.
  */
 function noGoAreasToParam(areas: NoGoArea[]): string {
   return areas
     .map((area) => {
-      const pts = area.points;
-      if (pts.length === 0) return null;
-      // Centroid
-      const cLat = pts.reduce((s, p) => s + p.lat, 0) / pts.length;
-      const cLon = pts.reduce((s, p) => s + p.lon, 0) / pts.length;
-      // Max distance from centroid in meters (approximate)
-      const maxDist = Math.max(
-        ...pts.map((p) => haversineMeters(cLat, cLon, p.lat, p.lon)),
-      );
-      return `${cLon},${cLat},${Math.ceil(maxDist)}`;
+      if (area.points.length < 3) return null;
+      return area.points.map((p) => `${p.lon},${p.lat}`).join(",");
     })
     .filter(Boolean)
     .join("|");
 }
 
-function haversineMeters(lat1: number, lon1: number, lat2: number, lon2: number): number {
-  const R = 6371000;
-  const dLat = ((lat2 - lat1) * Math.PI) / 180;
-  const dLon = ((lon2 - lon1) * Math.PI) / 180;
-  const a =
-    Math.sin(dLat / 2) ** 2 +
-    Math.cos((lat1 * Math.PI) / 180) *
-      Math.cos((lat2 * Math.PI) / 180) *
-      Math.sin(dLon / 2) ** 2;
-  return R * 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
-}
-
 export function getBRouterUrl(): string {
   return BROUTER_URL;
 }
diff --git a/docs/spec-drift.md b/docs/spec-drift.md
index 36d6612..95067cb 100644
--- a/docs/spec-drift.md
+++ b/docs/spec-drift.md
@@ -8,12 +8,7 @@ This document lists all known drifts between the OpenSpec specifications in `ope
 
 ## Active Drifts
 
-### 1. No-go areas are converted to circles for BRouter, not passed as polygons
-
-- **Spec**: `openspec/specs/brouter-integration/spec.md` — "BRouter request includes nogo parameters for each polygon"
-- **Implementation**: `apps/planner/app/lib/brouter.ts` (`noGoAreasToParam()`) converts each polygon to a circle by computing the centroid and using the maximum distance from centroid to any vertex as the radius. BRouter receives `lon,lat,radius` parameters, not polygon coordinates.
-- **Impact**: Routing avoidance is approximate. Elongated or concave polygons may not be accurately represented as circles, allowing routes to pass through parts of the drawn area.
-- **Resolution options**: Update the spec to document the circle approximation (BRouter only supports circle-based no-go areas), or implement polygon decomposition into multiple overlapping circles for better coverage.
+None — all identified drifts have been resolved.
 
 ---
 
@@ -23,9 +18,10 @@ Previously identified drifts that have been fixed via code changes or spec updat
 
 | # | Drift | Fixed in | Resolution |
 |---|-------|----------|------------|
-| 2 | PostGIS `geom` column never populated | PR #150, #151 | `setGeomFromGpx()` now populates geometry via `ST_GeomFromGeoJSON` on route/activity creation |
-| 3 | Planner metrics gauges always zero | PR #149 | Gauges wired to `.inc()`/`.dec()` in `yjs-server.ts` on client connect/disconnect |
-| 4 | Email provider spec said Resend, impl uses SMTP | PR #153 | Spec updated to document Nodemailer + SMTP |
+| 1 | PostGIS `geom` column never populated | PR #150, #151 | `setGeomFromGpx()` now populates geometry via `ST_GeomFromGeoJSON` on route/activity creation |
+| 2 | Planner metrics gauges always zero | PR #149 | Gauges wired to `.inc()`/`.dec()` in `yjs-server.ts` on client connect/disconnect |
+| 3 | Email provider spec said Resend, impl uses SMTP | PR #153 | Spec updated to document Nodemailer + SMTP |
+| 4 | No-go areas converted to circles instead of polygons | PR #155 | `noGoAreasToParam()` now passes polygon vertices directly via BRouter's `polygons` parameter |
 | 5 | Server type spec said CX21, Terraform has cx23 | PR #153 | Spec updated to document cx23 |
 | 6 | Secret files split into two instead of one | PR #153 | Spec updated to document `secrets.app.env` + `secrets.infra.env` split |
 | 7 | BRouter host failover spec said "within 5 seconds" | PR #153 | Spec updated to document immediate deterministic election |
diff --git a/openspec/specs/no-go-areas/spec.md b/openspec/specs/no-go-areas/spec.md
index 91dfdb0..dd6bfe4 100644
--- a/openspec/specs/no-go-areas/spec.md
+++ b/openspec/specs/no-go-areas/spec.md
@@ -9,7 +9,8 @@ Users SHALL be able to draw polygons on the map that BRouter avoids when computi
 
 #### Scenario: Route avoids no-go area
 - **WHEN** a route is computed and a no-go area intersects the direct path
-- **THEN** BRouter routes around the no-go area
+- **THEN** BRouter request includes the polygon vertices via the `polygons` parameter
+- **AND** BRouter routes around the no-go area
 
 #### Scenario: Delete no-go area
 - **WHEN** a user deletes a no-go area polygon