feat: always-visible tab close buttons + rApp dropdown shows open apps

- Tab close (×) buttons now visible at 35% opacity instead of hidden,
  brightening on hover so users can see they're clickable
- [+] dropdown now shows all rApps including already-open ones
- Already-open rApps shown dimmed with a cyan dot indicator
- Clicking an open rApp surfaces it (switches tab) instead of duplicating

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

shared/components/rstack-tab-bar.ts

@@ -282,21 +282,20 @@ export class RStackTabBar extends HTMLElement {
 		const existingModuleIds = new Set(this.#layers.map(l => l.moduleId));
 
 		// Use server module list if available, fall back to MODULE_BADGES keys
-		const availableModules: Array<{ id: string; name: string; icon: string; description: string }> =
+		const allModules: Array<{ id: string; name: string; icon: string; description: string }> =
 			this.#modules.length > 0
-				? this.#modules.filter(m => !existingModuleIds.has(m.id))
+				? this.#modules
 				: Object.keys(MODULE_BADGES)
-					.filter(id => !existingModuleIds.has(id))
 					.map(id => ({ id, name: id, icon: "", description: "" }));
 
-		if (availableModules.length === 0) {
+		if (allModules.length === 0) {
-			return `<div class="add-menu" id="add-menu"><div class="add-menu-empty">All rApps added</div></div>`;
+			return `<div class="add-menu" id="add-menu"><div class="add-menu-empty">No rApps available</div></div>`;
 		}
 
 		// Group by category
-		const groups = new Map<string, typeof availableModules>();
+		const groups = new Map<string, typeof allModules>();
-		const uncategorized: typeof availableModules = [];
+		const uncategorized: typeof allModules = [];
-		for (const m of availableModules) {
+		for (const m of allModules) {
 			const cat = MODULE_CATEGORIES[m.id];
 			if (cat) {
 				if (!groups.has(cat)) groups.set(cat, []);
@@ -311,29 +310,33 @@ export class RStackTabBar extends HTMLElement {
 			const items = groups.get(cat);
 			if (!items || items.length === 0) continue;
 			html += `<div class="add-menu-category">${cat}</div>`;
-			html += items.map(m => this.#renderAddMenuItem(m)).join("");
+			html += items.map(m => this.#renderAddMenuItem(m, existingModuleIds.has(m.id))).join("");
 		}
 		if (uncategorized.length > 0) {
 			html += `<div class="add-menu-category">Other</div>`;
-			html += uncategorized.map(m => this.#renderAddMenuItem(m)).join("");
+			html += uncategorized.map(m => this.#renderAddMenuItem(m, existingModuleIds.has(m.id))).join("");
 		}
 
 		return `<div class="add-menu" id="add-menu">${html}</div>`;
 	}
 
-	#renderAddMenuItem(m: { id: string; name: string; icon: string; description: string }): string {
+	#renderAddMenuItem(m: { id: string; name: string; icon: string; description: string }, isOpen: boolean): string {
 		const badge = MODULE_BADGES[m.id];
 		const badgeHtml = badge
 			? `<span class="add-menu-badge" style="background:${badge.color}">${badge.badge}</span>`
 			: `<span class="add-menu-icon">${m.icon}</span>`;
 
+		const openClass = isOpen ? " add-menu-item--open" : "";
+		const openIndicator = isOpen ? `<span class="add-menu-open-dot" title="Already open">●</span>` : "";
+
 		return `
-			<button class="add-menu-item" data-add-module="${m.id}">
+			<button class="add-menu-item${openClass}" data-add-module="${m.id}" data-module-open="${isOpen}">
 				${badgeHtml}
 				<div class="add-menu-text">
 					<span class="add-menu-name">${m.name} <span class="add-menu-emoji">${m.icon}</span></span>
 					${m.description ? `<span class="add-menu-desc">${m.description}</span>` : ""}
 				</div>
+				${openIndicator}
 			</button>
 		`;
 	}
@@ -615,11 +618,25 @@ export class RStackTabBar extends HTMLElement {
 			item.addEventListener("click", (e) => {
 				e.stopPropagation();
 				const moduleId = item.dataset.addModule!;
+				const isOpen = item.dataset.moduleOpen === "true";
 				this.#addMenuOpen = false;
-				this.dispatchEvent(new CustomEvent("layer-add", {
+
-					detail: { moduleId },
+				if (isOpen) {
-					bubbles: true,
+					// Surface existing tab instead of adding a duplicate
-				}));
+					const existing = this.#layers.find(l => l.moduleId === moduleId);
+					if (existing) {
+						this.setAttribute("active", existing.id);
+						this.dispatchEvent(new CustomEvent("layer-switch", {
+							detail: { layerId: existing.id, moduleId },
+							bubbles: true,
+						}));
+					}
+				} else {
+					this.dispatchEvent(new CustomEvent("layer-add", {
+						detail: { moduleId },
+						bubbles: true,
+					}));
+				}
 			});
 		});
 
@@ -984,12 +1001,12 @@ const STYLES = `
   color: inherit;
   font-size: 0.85rem;
   cursor: pointer;
-  opacity: 0;
+  opacity: 0.35;
   transition: opacity 0.15s, background 0.15s;
   padding: 0;
   line-height: 1;
 }
-.tab:hover .tab-close { opacity: 0.5; }
+.tab:hover .tab-close { opacity: 0.6; }
 .tab-close:hover { opacity: 1 !important; background: rgba(239,68,68,0.2); color: #ef4444; }
 
 /* ── Drag states ── */
@@ -1128,6 +1145,17 @@ const STYLES = `
   text-overflow: ellipsis;
 }
 
+.add-menu-item--open {
+  opacity: 0.55;
+}
+.add-menu-open-dot {
+  margin-left: auto;
+  font-size: 0.5rem;
+  color: #22d3ee;
+  flex-shrink: 0;
+  padding-left: 6px;
+}
+
 .add-menu-empty {
   padding: 12px;
   text-align: center;