diff --git a/internal/domain/domain.go b/internal/domain/domain.go
index 2c2a327..1183185 100644
--- a/internal/domain/domain.go
+++ b/internal/domain/domain.go
@@ -120,13 +120,13 @@ type Session struct {
 
 // Garden is a planning surface owned by one user, at real-world scale (cm).
 type Garden struct {
-	ID        int64   `json:"id"`
-	OwnerID   int64   `json:"ownerId"`
-	Name      string  `json:"name"`
-	WidthCM   float64 `json:"widthCm"`
-	HeightCM  float64 `json:"heightCm"`
-	UnitPref  string  `json:"unitPref"`
-	Notes     string  `json:"notes"`
+	ID       int64   `json:"id"`
+	OwnerID  int64   `json:"ownerId"`
+	Name     string  `json:"name"`
+	WidthCM  float64 `json:"widthCm"`
+	HeightCM float64 `json:"heightCm"`
+	UnitPref string  `json:"unitPref"`
+	Notes    string  `json:"notes"`
 	// GridSizeCM is the garden-scale grid spacing (cm) the editor draws its grid
 	// from; SnapToGrid, when true, snaps objects to that grid on place/move/resize.
 	GridSizeCM float64 `json:"gridSizeCm"`
@@ -183,9 +183,9 @@ type GardenObject struct {
 	GridSizeCM float64 `json:"gridSizeCm"`
 	SnapToGrid bool    `json:"snapToGrid"`
 	Notes      string  `json:"notes"`
-	Version     int64   `json:"version"`
-	CreatedAt   string  `json:"createdAt"`
-	UpdatedAt   string  `json:"updatedAt"`
+	Version    int64   `json:"version"`
+	CreatedAt  string  `json:"createdAt"`
+	UpdatedAt  string  `json:"updatedAt"`
 }
 
 // Plant is a catalog entry. OwnerID nil means a read-only seeded built-in.
diff --git a/internal/service/gardens.go b/internal/service/gardens.go
index d062889..460b3d7 100644
--- a/internal/service/gardens.go
+++ b/internal/service/gardens.go
@@ -166,7 +166,9 @@ func (s *Service) DeleteGarden(ctx context.Context, actorID, gardenID int64) err
 
 // gardenFromInput validates and normalizes input into a domain.Garden (without
 // identity/ownership fields). With applyDefaults, absent dimensions/unit are
-// filled in (create); without it, every field must be supplied (update).
+// filled in (create); without it, dimensions and unit must be supplied (update).
+// The grid size is the exception: 0 always means "unset" and is defaulted on both
+// paths, so an older client that omits it can't wipe the column to an invalid 0.
 func gardenFromInput(in GardenInput, applyDefaults bool) (*domain.Garden, error) {
 	name := strings.TrimSpace(in.Name)
 	if name == "" || len(name) > maxGardenNameLen {
diff --git a/web/src/editor/GardenCanvas.tsx b/web/src/editor/GardenCanvas.tsx
index d7ae5ac..90be8f6 100644
--- a/web/src/editor/GardenCanvas.tsx
+++ b/web/src/editor/GardenCanvas.tsx
@@ -157,15 +157,14 @@ export function GardenCanvas({
     if (!rect) return
     const world = screenToWorld({ x: e.clientX - rect.left, y: e.clientY - rect.top }, viewport)
     const local = worldToLocal(world, { x: focusedObject.xCm, y: focusedObject.yCm }, focusedObject.rotationDeg)
-    const halfW = focusedObject.widthCm / 2
-    const halfH = focusedObject.heightCm / 2
-    // Snap the plant to the bed's grid when the bed opts in; snapLocalToBedGrid
-    // also clamps, so the plain clamp covers the non-snapping case.
-    const placed = focusedObject.snapToGrid
-      ? snapLocalToBedGrid(local, focusedObject.gridSizeCm, halfW, halfH)
-      : { x: Math.max(-halfW, Math.min(halfW, local.x)), y: Math.max(-halfH, Math.min(halfH, local.y)) }
-    const x = placed.x
-    const y = placed.y
+    // snapLocalToBedGrid clamps to the bed either way; step 0 (snapping off) makes
+    // it a pure clamp, so both paths go through one helper.
+    const { x, y } = snapLocalToBedGrid(
+      local,
+      focusedObject.snapToGrid ? focusedObject.gridSizeCm : 0,
+      focusedObject.widthCm / 2,
+      focusedObject.heightCm / 2,
+    )
     const radiusCm = Math.max(1.5 * armedPlant.spacingCm, 15)
     // Stay armed for repeat-placement; don't select (the placement sheet covers
     // the object, so a selection would be hidden until placement ends anyway).
@@ -178,9 +177,16 @@ export function GardenCanvas({
   // Draw the bed's own grid inside a focused plantable bed that has snapping on,
   // so the user sees exactly where plants will land. Lines are in the bed's local
   // frame (origin at center), anchored to the corner to match snapLocalToBedGrid.
-  const showBedGrid = !!focusedObject && focusedObject.plantable && focusedObject.snapToGrid
-  const bedVLines = showBedGrid ? bedGridLines(halfFW, focusedObject.gridSizeCm) : []
-  const bedHLines = showBedGrid ? bedGridLines(halfFH, focusedObject.gridSizeCm) : []
+  // Memoized so a high-frequency plop drag (which re-renders the canvas on every
+  // pointermove) doesn't rebuild the line arrays each frame. null when the focused
+  // object isn't a snapping plantable bed.
+  const bedGrid = useMemo(() => {
+    if (!focusedObject || !focusedObject.plantable || !focusedObject.snapToGrid) return null
+    return {
+      v: bedGridLines(focusedObject.widthCm / 2, focusedObject.gridSizeCm),
+      h: bedGridLines(focusedObject.heightCm / 2, focusedObject.gridSizeCm),
+    }
+  }, [focusedObject])
 
   return (
     <div ref={containerRef} className="relative h-full w-full overflow-hidden rounded-xl border border-border bg-bg">
@@ -210,12 +216,12 @@ export function GardenCanvas({
             </g>
           ))}
 
-          {showBedGrid && focusedObject && (
+          {focusedObject && bedGrid && (
             <g transform={objectTransform(focusedObject)} pointerEvents="none">
-              {bedVLines.map((x) => (
+              {bedGrid.v.map((x) => (
                 <line key={`v${x}`} x1={x} y1={-halfFH} x2={x} y2={halfFH} stroke="#3f8f4f" strokeOpacity={0.3} strokeWidth={1} vectorEffect="non-scaling-stroke" />
               ))}
-              {bedHLines.map((y) => (
+              {bedGrid.h.map((y) => (
                 <line key={`h${y}`} x1={-halfFW} y1={y} x2={halfFW} y2={y} stroke="#3f8f4f" strokeOpacity={0.3} strokeWidth={1} vectorEffect="non-scaling-stroke" />
               ))}
             </g>
diff --git a/web/src/editor/Inspector.tsx b/web/src/editor/Inspector.tsx
index 8582553..ed3f293 100644
--- a/web/src/editor/Inspector.tsx
+++ b/web/src/editor/Inspector.tsx
@@ -263,14 +263,14 @@ export function Inspector({
           </div>
         )}
 
-          <TextArea
-            label="Notes"
-            name="notes"
-            rows={2}
-            value={notes}
-            onChange={(e) => setNotes(e.target.value)}
-            onBlur={() => notes !== object.notes && patch({ notes })}
-          />
+        <TextArea
+          label="Notes"
+          name="notes"
+          rows={2}
+          value={notes}
+          onChange={(e) => setNotes(e.target.value)}
+          onBlur={() => notes !== object.notes && patch({ notes })}
+        />
       </fieldset>
 
       {!readOnly &&
diff --git a/web/src/editor/PlopOverlay.tsx b/web/src/editor/PlopOverlay.tsx
index 75eeb03..f6247c8 100644
--- a/web/src/editor/PlopOverlay.tsx
+++ b/web/src/editor/PlopOverlay.tsx
@@ -63,11 +63,6 @@ export function PlopOverlay({
     }
   }
 
-  const clampLocal = (p: Point): Point => ({
-    x: Math.max(-halfW, Math.min(halfW, p.x)),
-    y: Math.max(-halfH, Math.min(halfH, p.y)),
-  })
-
   const begin = (
     e: ReactPointerEvent,
     onMove: (e: PointerEvent) => EditorPlanting,
@@ -110,8 +105,9 @@ export function PlopOverlay({
       (ev) => {
         const p = ptr(ev)
         const moved: Point = { x: base.xCm + (p.x - start.x), y: base.yCm + (p.y - start.y) }
-        // snapLocalToBedGrid clamps too, so the plain clamp covers the non-snap case.
-        const next = snap ? snapLocalToBedGrid(moved, gridCm, halfW, halfH) : clampLocal(moved)
+        // snapLocalToBedGrid clamps either way; step 0 (snapping off) makes it a
+        // pure clamp, so both paths go through one helper.
+        const next = snapLocalToBedGrid(moved, snap ? gridCm : 0, halfW, halfH)
         return { ...base, xCm: next.x, yCm: next.y }
       },
       (f) => ({ id: base.id, version: base.version, xCm: f.xCm, yCm: f.yCm }),
diff --git a/web/src/lib/geometry.ts b/web/src/lib/geometry.ts
index 7606e0f..47dd5d4 100644
--- a/web/src/lib/geometry.ts
+++ b/web/src/lib/geometry.ts
@@ -91,12 +91,12 @@ export function snapPoint(p: Point, step: number): Point {
  * clamped, not snapped.
  */
 export function snapLocalToBedGrid(p: Point, step: number, halfW: number, halfH: number): Point {
-  const sx = step > 0 ? -halfW + Math.round((p.x + halfW) / step) * step : p.x
-  const sy = step > 0 ? -halfH + Math.round((p.y + halfH) / step) * step : p.y
-  return {
-    x: Math.max(-halfW, Math.min(halfW, sx)),
-    y: Math.max(-halfH, Math.min(halfH, sy)),
-  }
+  // Snap one axis to the grid anchored at -half (the bed's near edge), then clamp
+  // to [-half, half]. step<=0 skips the snap, so callers can pass step 0 to get a
+  // pure clamp — the non-snapping placement/move path — through the same helper.
+  const snapAxis = (v: number, half: number) =>
+    Math.max(-half, Math.min(half, step > 0 ? -half + Math.round((v + half) / step) * step : v))
+  return { x: snapAxis(p.x, halfW), y: snapAxis(p.y, halfH) }
 }
 
 /** Linear interpolation. */