fix(explore): make the whole collapsed rail expand on tap

apps/escurel-explore/lib/crm/crm_workspace.dart

@@ -176,11 +176,33 @@ class _CollapsibleRegion extends StatelessWidget {
     );
 
     if (collapsed) {
+      // The whole collapsed rail is the expand target. A centered 16px icon
+      // is far too small to reliably hit — and when *both* panes collapse
+      // the right rail balloons to a wide blank area — so an InkWell fills
+      // the region and re-expands on a tap anywhere within it.
       return Semantics(
         label: label,
         container: true,
         explicitChildNodes: true,
-        child: Center(child: toggle),
+        child: Semantics(
+          label: '$label-expand',
+          button: true,
+          onTap: onToggle,
+          excludeSemantics: true,
+          child: Tooltip(
+            message: 'Expand',
+            child: InkWell(
+              onTap: onToggle,
+              child: Center(
+                child: Icon(
+                  edge == _Edge.right ? Icons.chevron_right : Icons.chevron_left,
+                  size: 16,
+                  color: kOnSurfaceVariant,
+                ),
+              ),
+            ),
+          ),
+        ),
       );
     }
     return Semantics(

apps/escurel-explore/test/crm/both_panes_collapse_test.dart

@@ -0,0 +1,83 @@
+// Reproduction for the live report: on an instance, collapsing BOTH panes
+// leaves the expand chevrons unresponsive. Drives the real chevrons via
+// the pointer path over the real fixture.
+
+import 'package:escurel_explore/client/escurel_client.dart';
+import 'package:escurel_explore/client/fixture_escurel_client.dart';
+import 'package:escurel_explore/crm/crm_workspace.dart';
+import 'package:escurel_explore/state/providers.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+EscurelClient _corpus() => FixtureEscurelClient.fromSources(
+      skillFiles: const {
+        'customer.md': '---\ntype: skill\nid: customer\ndescription: A buying org.\n---\n# customer\n',
+      },
+      instanceFiles: const {
+        'customer__acme.md':
+            '---\ntype: instance\nskill: customer\nid: acme\nname: Acme Ltd\n---\n# Acme Ltd\n',
+      },
+    );
+
+Future<void> _pump(WidgetTester tester) async {
+  tester.view.physicalSize = const Size(1400, 900);
+  tester.view.devicePixelRatio = 1.0;
+  addTearDown(tester.view.resetPhysicalSize);
+  addTearDown(tester.view.resetDevicePixelRatio);
+  await tester.pumpWidget(
+    ProviderScope(
+      overrides: [escurelClientProvider.overrideWithValue(_corpus())],
+      child: const MaterialApp(home: CrmWorkspace()),
+    ),
+  );
+  await tester.pumpAndSettle();
+}
+
+void main() {
+  testWidgets('collapse both panes, then both expand chevrons work', (tester) async {
+    await _pump(tester);
+
+    // Collapse the left (events) pane.
+    await tester.tap(find.bySemanticsLabel('region-events-collapse'));
+    await tester.pumpAndSettle();
+    // Collapse the right (instance) pane.
+    await tester.tap(find.bySemanticsLabel('region-instance-collapse'));
+    await tester.pumpAndSettle();
+
+    // Both collapsed: two expand chevrons, no panes.
+    expect(find.bySemanticsLabel('region-events-expand'), findsOneWidget);
+    expect(find.bySemanticsLabel('region-instance-expand'), findsOneWidget);
+    expect(find.bySemanticsLabel('event-pane'), findsNothing);
+    expect(find.bySemanticsLabel('instance-pane'), findsNothing);
+
+    // Expand the right pane.
+    await tester.tap(find.bySemanticsLabel('region-instance-expand'));
+    await tester.pumpAndSettle();
+    expect(find.bySemanticsLabel('instance-pane'), findsOneWidget,
+        reason: 'right pane must re-expand');
+
+    // Expand the left pane.
+    await tester.tap(find.bySemanticsLabel('region-events-expand'));
+    await tester.pumpAndSettle();
+    expect(find.bySemanticsLabel('event-pane'), findsOneWidget,
+        reason: 'left pane must re-expand');
+  });
+
+  testWidgets('a tap anywhere in the collapsed rail re-expands it (not just the icon)', (tester) async {
+    await _pump(tester);
+
+    await tester.tap(find.bySemanticsLabel('region-events-collapse'));
+    await tester.pumpAndSettle();
+    expect(find.bySemanticsLabel('event-pane'), findsNothing);
+
+    // Tap near the TOP of the collapsed rail — far from the vertically
+    // centered chevron icon. Before the full-rail hit target, only the
+    // ~16px icon responded, so a real click that missed it did nothing.
+    final rail = tester.getRect(find.bySemanticsLabel('region-events'));
+    await tester.tapAt(Offset(rail.center.dx, rail.top + 24));
+    await tester.pumpAndSettle();
+    expect(find.bySemanticsLabel('event-pane'), findsOneWidget,
+        reason: 'tapping the rail (off the icon) must still expand it');
+  });
+}

docs/notes/discovered/2026-05-31-collapsed-rail-tiny-hit-target.md

@@ -0,0 +1,33 @@
+# A collapsed pane's expand chevron was a too-small hit target
+
+**Symptom.** On the CRM workspace, collapsing a pane worked, but the
+**expand** chevron in the resulting rail often did nothing for a real
+mouse — "I can collapse, but afterwards expand is not possible." Worst
+when *both* panes were collapsed (a near-blank screen with two tiny
+chevrons that wouldn't respond).
+
+**Cause.** The collapsed rail rendered `Center(child: toggle)` where
+`toggle` was a 16px `IconButton`. Only that ~16–28px icon was
+tappable. The collapse button, by contrast, lives in a full-width 28px
+header bar (easy to hit) — hence "collapse works, expand doesn't." When
+both panes collapse, the *right* rail also balloons to most of the
+width (`leftW = rail`, `rightW = w - rail - divW`), so the chevron sits
+alone in a large blank region that ignores clicks everywhere except the
+icon.
+
+**Why tests missed it.** `tester.tap(find.bySemanticsLabel(...))` taps
+the widget's **center**, which is exactly where the icon is — so every
+collapse/expand test passed while real off-icon clicks failed. The
+regression test now uses `tester.tapAt(...)` at an offset *away* from the
+centered icon (near the top of the rail) to exercise the real hit area.
+
+**Fix.** Make the whole collapsed rail the tap target: wrap the rail in
+an `InkWell(onTap: onToggle)` filling the region, with the chevron
+centered for affordance. A tap anywhere in the rail re-expands it.
+
+**How to recognise it.** A control that "doesn't work" for real users
+but passes every widget test. Check whether the tappable area is a small
+centered child while the test taps dead-center — `tester.tap` hits the
+center regardless of size, so it cannot catch an undersized hit target.
+Use `tapAt` with an offset, and prefer generous, full-region hit targets
+for rails/toggles.