Fix minimap drag visual feedback and domain zoom to include sub-domains

- Minimap: update viewport rect locally during drag so it visually
  follows the pointer (was suppressed by _suppressViewportUpdates)
- Domain zoom: compute union bounding box of domain + all descendants
  so parent domains encompass their sub-domain regions

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jeremymanning

src/app.js

@@ -494,12 +494,28 @@ async function switchDomain(domainId) {
 
   if (!allDomainBundle) return;
 
-  // Look up the target domain's region from the registry (index.json)
-  // — the single source of truth for bounding boxes.
+  // Look up the target domain's region from the registry (index.json).
+  // For parent domains, compute the union bounding box of the domain + all descendants
+  // so the view encompasses all sub-domain content.
   let targetRegion = GLOBAL_REGION;
   const registryEntry = registry.getDomain(domainId);
   if (registryEntry && registryEntry.region) {
-    targetRegion = registryEntry.region;
+    const descendants = registry.getDescendants(domainId);
+    if (descendants.length > 0) {
+      let { x_min, x_max, y_min, y_max } = registryEntry.region;
+      for (const descId of descendants) {
+        const desc = registry.getDomain(descId);
+        if (desc && desc.region) {
+          x_min = Math.min(x_min, desc.region.x_min);
+          x_max = Math.max(x_max, desc.region.x_max);
+          y_min = Math.min(y_min, desc.region.y_min);
+          y_max = Math.max(y_max, desc.region.y_max);
+        }
+      }
+      targetRegion = { x_min, x_max, y_min, y_max };
+    } else {
+      targetRegion = registryEntry.region;
+    }
   }
 
   // Ensure the domain bundle is loaded/cached (for questions & labels).

src/viz/minimap.js

@@ -210,6 +210,14 @@ export class Minimap {
     const clampedCx = Math.max(vpW / 2, Math.min(1 - vpW / 2, cx));
     const clampedCy = Math.max(vpH / 2, Math.min(1 - vpH / 2, cy));
 
+    // Update viewport rect locally during drag (round-trip is suppressed)
+    this.currentViewport = {
+      x_min: clampedCx - vpW / 2, x_max: clampedCx + vpW / 2,
+      y_min: clampedCy - vpH / 2, y_max: clampedCy + vpH / 2,
+    };
+    this.render();
+    this._didDrag = true;
+
     this.panHandler(clampedCx, clampedCy, false);
   }