feat: customizable link color per edge

- Add custom_color field to EdgeData type, Edge DB model and all schemas
- HomelableEdge applies custom_color as stroke override (before selected highlight)
- EDGE_DEFAULT_COLORS extracted to utils/edgeColors.ts (react-refresh compliant)
- EdgeModal: color picker row showing effective color (custom or type default)
  with hex value, Reset button when custom color is active
- Auto-migration adds custom_color column to edges table

frontend/src/App.tsx

@@ -64,6 +64,7 @@ export default function App() {
         label: e.data?.label ?? null,
         vlan_id: e.data?.vlan_id ?? null,
         speed: e.data?.speed ?? null,
+        custom_color: e.data?.custom_color ?? null,
       }))
       await canvasApi.save({ nodes: nodesToSave, edges: edgesToSave, viewport: {} })
       markSaved()

frontend/src/components/canvas/edges/index.tsx

@@ -26,9 +26,11 @@ export function HomelableEdge({ id, sourceX, sourceY, targetX, targetY, sourcePo
   const [edgePath, labelX, labelY] = getBezierPath({ sourceX, sourceY, sourcePosition, targetX, targetY, targetPosition })
 
   const edgeType: EdgeType = data?.type ?? 'ethernet'
+  const customColor = data?.custom_color as string | undefined
   const style: React.CSSProperties = {
     ...EDGE_STYLES[edgeType],
     ...(edgeType === 'vlan' ? { stroke: getVlanColor(data?.vlan_id as number | undefined) } : {}),
+    ...(customColor ? { stroke: customColor } : {}),
     ...(selected ? { stroke: '#00d4ff', filter: 'drop-shadow(0 0 4px #00d4ff88)' } : {}),
   }
 

frontend/src/components/modals/EdgeModal.tsx

@@ -1,10 +1,12 @@
 import { useState } from 'react'
+import { RotateCcw } from 'lucide-react'
 import { Dialog, DialogContent, DialogHeader, DialogTitle } from '@/components/ui/dialog'
 import { Button } from '@/components/ui/button'
 import { Input } from '@/components/ui/input'
 import { Label } from '@/components/ui/label'
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select'
 import { EDGE_TYPE_LABELS, type EdgeData, type EdgeType } from '@/types'
+import { EDGE_DEFAULT_COLORS } from '@/utils/edgeColors'
 
 const EDGE_TYPES = Object.entries(EDGE_TYPE_LABELS) as [EdgeType, string][]
 
@@ -21,6 +23,9 @@ export function EdgeModal({ open, onClose, onSubmit, onDelete, initial, title =
   const [type, setType] = useState<EdgeType>(initial?.type ?? 'ethernet')
   const [label, setLabel] = useState(initial?.label ?? '')
   const [vlanId, setVlanId] = useState(initial?.vlan_id?.toString() ?? '')
+  const [customColor, setCustomColor] = useState<string | undefined>(initial?.custom_color)
+
+  const effectiveColor = customColor ?? EDGE_DEFAULT_COLORS[type]
 
   const handleSubmit = (e: React.FormEvent) => {
     e.preventDefault()
@@ -28,6 +33,7 @@ export function EdgeModal({ open, onClose, onSubmit, onDelete, initial, title =
       type,
       label: label || undefined,
       vlan_id: type === 'vlan' && vlanId ? parseInt(vlanId) : undefined,
+      custom_color: customColor,
     })
     onClose()
   }
@@ -84,6 +90,37 @@ export function EdgeModal({ open, onClose, onSubmit, onDelete, initial, title =
             />
           </div>
 
+          <div className="flex flex-col gap-1.5">
+            <div className="flex items-center justify-between">
+              <Label className="text-xs text-muted-foreground">Color</Label>
+              {customColor && (
+                <button
+                  type="button"
+                  onClick={() => setCustomColor(undefined)}
+                  className="flex items-center gap-1 text-[10px] text-muted-foreground/60 hover:text-muted-foreground transition-colors"
+                >
+                  <RotateCcw size={10} /> Reset
+                </button>
+              )}
+            </div>
+            <label
+              className="relative flex items-center gap-2.5 px-2.5 h-8 rounded-md border cursor-pointer"
+              style={{ borderColor: customColor ? effectiveColor : '#30363d', background: '#21262d' }}
+            >
+              <input
+                type="color"
+                value={effectiveColor}
+                onChange={(e) => setCustomColor(e.target.value)}
+                className="absolute opacity-0 w-0 h-0"
+              />
+              <div className="w-4 h-4 rounded-sm shrink-0 border border-white/10" style={{ background: effectiveColor }} />
+              <span className="font-mono text-xs" style={{ color: customColor ? effectiveColor : '#8b949e' }}>
+                {effectiveColor}
+              </span>
+              {!customColor && <span className="text-[10px] text-muted-foreground/50 ml-auto">default</span>}
+            </label>
+          </div>
+
           <div className="flex justify-between gap-2 pt-1">
             {onDelete ? (
               <Button type="button" variant="ghost" size="sm" className="text-[#f85149] hover:text-[#f85149] hover:bg-[#f85149]/10" onClick={handleDelete}>

frontend/src/types/index.ts

@@ -49,6 +49,7 @@ export interface EdgeData extends Record<string, unknown> {
   label?: string
   vlan_id?: number
   speed?: string
+  custom_color?: string
 }
 
 export const NODE_TYPE_LABELS: Record<NodeType, string> = {

frontend/src/utils/edgeColors.ts

@@ -0,0 +1,9 @@
+import type { EdgeType } from '@/types'
+
+export const EDGE_DEFAULT_COLORS: Record<EdgeType, string> = {
+  ethernet: '#30363d',
+  wifi: '#00d4ff',
+  iot: '#e3b341',
+  vlan: '#00d4ff',
+  virtual: '#8b949e',
+}