fix: make sidebar Signals section header collapsible

src/app/analyzer/sidebar/sidebar.html

@@ -40,7 +40,11 @@ <h3 (click)="toggleSection('anomalyScanner')">Anomaly Scanner</h3>
     class="control-group flex-grow gray-box"
     [class.collapsed]="isSectionCollapsed('signals')"
   >
-    <app-signal-list-panel idPrefix="chk-left"></app-signal-list-panel>
+    <app-signal-list-panel
+      idPrefix="chk-left"
+      [collapsed]="isSectionCollapsed('signals')"
+      (titleClick)="toggleSection('signals')"
+    ></app-signal-list-panel>
   </div>
 
   <div

src/app/analyzer/signal-list-panel/signal-list-panel.html

@@ -1,10 +1,23 @@
-<div class="group-header-row">
+<div class="group-header-row" (click)="titleClick.emit()">
   <h3>Signals</h3>
+  @if (!collapsed()) {
   <div class="button-row-sw">
-    <button class="btn btn-sm" (click)="toggleAllSignals(true)">All</button>
-    <button class="btn btn-sm" (click)="toggleAllSignals(false)">None</button>
+    <button
+      class="btn btn-sm"
+      (click)="toggleAllSignals(true); $event.stopPropagation()"
+    >
+      All
+    </button>
+    <button
+      class="btn btn-sm"
+      (click)="toggleAllSignals(false); $event.stopPropagation()"
+    >
+      None
+    </button>
   </div>
+  }
 </div>
+@if (!collapsed()) {
 <p class="section-description">
   Search and select signals to display on the chart.
 </p>
@@ -169,3 +182,4 @@ <h3>Signals</h3>
   </div>
   } }
 </div>
+}

src/app/analyzer/signal-list-panel/signal-list-panel.ts

@@ -1,4 +1,4 @@
-import { Component, inject, input, signal } from '@angular/core';
+import { Component, inject, input, output, signal } from '@angular/core';
 import { AppStateService } from '../../core/app-state.service';
 import { LoadedFile } from '../../core/models';
 import { PreferencesService } from '../../core/preferences.service';
@@ -34,6 +34,18 @@ interface CategoryGroup {
 export class SignalListPanel {
   readonly idPrefix = input('chk');
 
+  /**
+   * Whether the caller's wrapping section is collapsed. This component owns its own "Signals"
+   * title (shared with SignalsEdgePanel, which never collapses it), so Sidebar can't just hide
+   * this whole element the way it does for its other sections -- instead it passes the collapsed
+   * state in and this component hides its own body while keeping the header (and the way back
+   * to expand it) visible.
+   */
+  readonly collapsed = input(false);
+
+  /** Emitted when the title row is clicked; Sidebar wires this to its own toggleSection('signals'). */
+  readonly titleClick = output<void>();
+
   protected readonly appState = inject(AppStateService);
   protected readonly preferences = inject(PreferencesService);
   private readonly palette = inject(SignalPaletteService);

src/styles.css

@@ -238,7 +238,8 @@ body:not(.dark-theme) .sidebar h2 {
   float: right;
 }
 
-.control-group.collapsed > :not(h3, .group-header, .group-header-row) {
+.control-group.collapsed
+  > :not(h3, .group-header, .group-header-row, app-signal-list-panel) {
   display: none !important;
 }