feat(editor): highlight selected connection endpoints

src/app/services/graph-selection/graph-selection.ts

@@ -4,17 +4,30 @@
 
 import { Injectable, signal } from '@angular/core';
 
+export type SelectedConnection = {
+  id: string;
+  sourceId: string;
+  sourceOutput: string;
+  targetId: string;
+  targetInput: string;
+};
+
 @Injectable({ providedIn: 'root' })
 export class GraphSelectionService {
   readonly selectedConnectionId = signal<string | null>(null);
+  /** The two endpoints let their socket components light up with the selected wire. */
+  readonly selectedConnection = signal<SelectedConnection | null>(null);
   readonly deleteConnectionRequestTick = signal(0);
 
-  selectConnection(connectionId: string | null | undefined) {
-    this.selectedConnectionId.set(connectionId ? String(connectionId) : null);
+  selectConnection(connectionId: string | null | undefined, endpoints?: Omit<SelectedConnection, 'id'>) {
+    const id = connectionId ? String(connectionId) : null;
+    this.selectedConnectionId.set(id);
+    this.selectedConnection.set(id && endpoints ? { id, ...endpoints } : null);
   }
 
   clearConnectionSelection() {
     this.selectedConnectionId.set(null);
+    this.selectedConnection.set(null);
   }
 
   requestDeleteSelectedConnection() {

src/app/shared/custom-connection/custom-connection.ts

@@ -20,7 +20,9 @@ import { BiasComparisonViewStateService } from '@services/bias/bias-comparison-v
   selector: 'app-custom-connection',
   standalone: true,
   template: `
-    <svg data-testid="connection" [attr.data-connection-id]="connectionId" [attr.data-loop-back]="isLoopBack || null">
+    <svg data-testid="connection" [attr.data-connection-id]="connectionId" [attr.data-loop-back]="isLoopBack || null"
+      [attr.data-connection-kind]="connectionKind" [attr.data-selected]="isSelected || null"
+      [style.z-index]="isSelected ? 100 : 1">
       <path
         [class.connection-readonly]="isReadonly"
         [attr.d]="drawnPath"
@@ -214,6 +216,10 @@ export class CustomConnectionComponent {
     return String(this.data?.id ?? '');
   }
 
+  get connectionKind(): 'data' | 'dependency' | 'resource' {
+    return this.isResourceLink ? 'resource' : this.isDependencyConnection ? 'dependency' : 'data';
+  }
+
   private get loopData(): LoopAwareConnection | undefined {
     return this.data as LoopAwareConnection | undefined;
   }
@@ -294,7 +300,9 @@ export class CustomConnectionComponent {
   }
 
   get strokeColor(): string {
-    if (this.isSelected) return '#f97316';
+    if (this.isSelected) {
+      return this.isResourceLink ? '#0f9f8d' : this.isDependencyConnection ? '#4f46e5' : '#f97316';
+    }
     if (this.isBiasRoutingChange) return '#b45309';
     if (this.isLoopBack) return '#7c3aed';
     if (this.isResourceLink) return '#0f766e';
@@ -302,14 +310,16 @@ export class CustomConnectionComponent {
   }
 
   get strokeWidth(): number {
-    if (this.isSelected) return this.isDependencyConnection || this.isResourceLink ? 3.25 : 6;
+    if (this.isSelected) return this.isDependencyConnection || this.isResourceLink ? 4 : 6;
     if (this.isBiasRoutingChange) return 6;
     return this.isDependencyConnection || this.isResourceLink ? 2.25 : 5;
   }
 
   get strokeDasharray(): string | null {
     if (this.isLoopBack) return '12 7';
-    if (this.isResourceLink) return '2 6';
+    // A resource is a capability handle, not an ordering dependency: its teal segmented wire is
+    // intentionally unlike the thin grey dashed dependency wire.
+    if (this.isResourceLink) return '14 5 2 5';
     return this.isDependencyConnection ? '6 6' : null;
   }
 
@@ -329,7 +339,12 @@ export class CustomConnectionComponent {
     if (this.isReadonly) return;
     event.preventDefault();
     event.stopPropagation();
-    this.graphSelection.selectConnection(this.connectionId);
+    this.graphSelection.selectConnection(this.connectionId, {
+      sourceId: String(this.data?.source ?? ''),
+      sourceOutput: String(this.data?.sourceOutput ?? ''),
+      targetId: String(this.data?.target ?? ''),
+      targetInput: String(this.data?.targetInput ?? '')
+    });
   }
 
   deleteConnection(event: Event) {

src/app/shared/custom-socket/custom-socket.ts

@@ -12,6 +12,7 @@ import {
   Input,
   OnDestroy
 } from "@angular/core";
+import { GraphSelectionService } from '@services/graph-selection/graph-selection';
 
 @Component({
   template: ``,
@@ -22,6 +23,7 @@ export class CustomSocket implements AfterViewInit, OnDestroy {
   @Input() emit!: any;
   @Input() rendered!: any;
   private readonly element = inject<ElementRef<HTMLElement>>(ElementRef);
+  private readonly graphSelection = inject(GraphSelectionService);
   private resizeObserver: ResizeObserver | null = null;
   private renderFrame: number | null = null;
   private side: "input" | "output" = "input";
@@ -33,6 +35,7 @@ export class CustomSocket implements AfterViewInit, OnDestroy {
 
   @HostBinding("style.width")
   get width() {
+    if (this.isSelectedEndpoint) return this.kind === "resource" ? "11px" : "12px";
     return this.kind === "resource" ? "7px" : "8px";
   }
 
@@ -45,7 +48,13 @@ export class CustomSocket implements AfterViewInit, OnDestroy {
   @HostBinding("style.borderRadius") get borderRadius() {
     return this.kind === "resource" ? "4px" : "999px";
   }
-  @HostBinding("style.border") border = "1px solid rgba(255,255,255,0.9)";
+  @HostBinding("style.border") get border() {
+    return this.isSelectedEndpoint ? "2px solid #fff" : "1px solid rgba(255,255,255,0.9)";
+  }
+
+  @HostBinding('attr.data-connection-endpoint-selected') get selectedEndpointAttribute() {
+    return this.isSelectedEndpoint || null;
+  }
   @HostBinding("style.cursor") get cursor() {
     return this.data?.__readonly === true ? "default" : "crosshair";
   }
@@ -56,6 +65,13 @@ export class CustomSocket implements AfterViewInit, OnDestroy {
 
   @HostBinding("style.background")
   get bg() {
+    if (this.isSelectedEndpoint) {
+      return this.kind === 'resource'
+        ? 'linear-gradient(145deg, #5eead4 0%, #0f9f8d 100%)'
+        : this.kind === 'dependency'
+          ? 'linear-gradient(145deg, #a5b4fc 0%, #4f46e5 100%)'
+          : 'linear-gradient(145deg, #fdba74 0%, #ea580c 100%)';
+    }
     if (this.kind === "resource") {
       return "linear-gradient(180deg, #5eead4 0%, #0f766e 100%)";
     }
@@ -71,6 +87,12 @@ export class CustomSocket implements AfterViewInit, OnDestroy {
 
   @HostBinding("style.boxShadow")
   get sh() {
+    if (this.isSelectedEndpoint) {
+      const color = this.kind === 'resource' ? 'rgba(15,159,141,0.78)'
+        : this.kind === 'dependency' ? 'rgba(79,70,229,0.72)'
+          : 'rgba(234,88,12,0.72)';
+      return `0 0 0 4px ${color}, 0 5px 14px ${color}`;
+    }
     if (this.kind === "resource") {
       return "0 1px 4px rgba(15,118,110,0.32), 0 0 0 1px rgba(13,148,136,0.42)";
     }
@@ -92,6 +114,18 @@ export class CustomSocket implements AfterViewInit, OnDestroy {
     return kind === "dependency" || kind === "resource" ? kind : "data";
   }
 
+  /** True for either end of the selected data, dependency or resource connection. */
+  get isSelectedEndpoint(): boolean {
+    const selected = this.graphSelection.selectedConnection();
+    if (!selected) return false;
+    const nodeId = this.data?.nodeId ?? this.data?.payload?.nodeId;
+    const key = this.data?.key ?? this.data?.payload?.key;
+    if (nodeId == null || key == null) return false;
+    return this.side === 'output'
+      ? String(nodeId) === selected.sourceId && String(key) === selected.sourceOutput
+      : String(nodeId) === selected.targetId && String(key) === selected.targetInput;
+  }
+
   ngOnChanges(): void {
     this.side = this.resolveSocketSide();
     this.kind = this.resolveSocketKind();