feat: draggable tab reordering (#168)

Adds HTML5 drag-and-drop support to conversation tabs, allowing users to
reorder tabs by dragging. Visual feedback via opacity and border highlight.
Keyboard navigation (Ctrl+Tab) respects custom tab order.

src/lib/components/ConversationTabs.svelte

@@ -12,6 +12,25 @@
   let editingTabId = $state<string | null>(null);
   let editingName = $state("");
 
+  // Tab order for pointer-drag reordering
+  let tabOrder = $state<string[]>([]);
+  let draggedId = $state<string | null>(null);
+  let dragOverId = $state<string | null>(null);
+  let dragStartX = 0;
+  let isDragging = false;
+  let wasDragged = false;
+  let tabsRef = $state<HTMLElement | null>(null);
+
+  // Keep tabOrder in sync with conversations map (add new, remove deleted)
+  $effect(() => {
+    const currentIds = Array.from($conversations.keys());
+    const validIds = tabOrder.filter((id) => currentIds.includes(id));
+    const newIds = currentIds.filter((id) => !tabOrder.includes(id));
+    if (validIds.length !== tabOrder.length || newIds.length > 0) {
+      tabOrder = [...validIds, ...newIds];
+    }
+  });
+
   // Track last seen message count for each conversation
   let lastSeenMessageCount = new SvelteMap<string, number>();
 
@@ -138,6 +157,63 @@
     }
   }
 
+  async function handleTabClick(id: string) {
+    if (wasDragged) {
+      wasDragged = false;
+      return;
+    }
+    await switchTab(id);
+  }
+
+  function handlePointerDown(event: PointerEvent, id: string) {
+    if (editingTabId === id) return;
+    draggedId = id;
+    dragStartX = event.clientX;
+    isDragging = false;
+    wasDragged = false;
+
+    function onMove(e: PointerEvent) {
+      if (!isDragging && Math.abs(e.clientX - dragStartX) > 5) {
+        isDragging = true;
+      }
+      if (!isDragging || !tabsRef) return;
+      const tabs = tabsRef.querySelectorAll<HTMLElement>("[data-tab-id]");
+      dragOverId = null;
+      for (const tab of tabs) {
+        const rect = tab.getBoundingClientRect();
+        if (e.clientX >= rect.left && e.clientX <= rect.right) {
+          const tabId = tab.dataset.tabId;
+          if (tabId && tabId !== id) {
+            dragOverId = tabId;
+          }
+          break;
+        }
+      }
+    }
+
+    function onUp() {
+      if (isDragging && draggedId && dragOverId && draggedId !== dragOverId) {
+        const order = [...tabOrder];
+        const fromIndex = order.indexOf(draggedId);
+        const toIndex = order.indexOf(dragOverId);
+        order.splice(fromIndex, 1);
+        order.splice(toIndex, 0, draggedId);
+        tabOrder = order;
+        wasDragged = true;
+      }
+      draggedId = null;
+      dragOverId = null;
+      isDragging = false;
+      window.removeEventListener("pointermove", onMove);
+      window.removeEventListener("pointerup", onUp);
+      window.removeEventListener("pointercancel", onUp);
+    }
+
+    window.addEventListener("pointermove", onMove);
+    window.addEventListener("pointerup", onUp);
+    window.addEventListener("pointercancel", onUp);
+  }
+
   // Keyboard shortcuts
   onMount(() => {
     function handleGlobalKeydown(event: KeyboardEvent) {
@@ -165,21 +241,19 @@
       // Ctrl/Cmd + Tab: Next tab
       else if ((event.ctrlKey || event.metaKey) && event.key === "Tab" && !event.shiftKey) {
         event.preventDefault();
-        const tabs = Array.from($conversations.keys());
-        const currentIndex = tabs.findIndex((id) => id === $activeConversationId);
+        const currentIndex = tabOrder.findIndex((id) => id === $activeConversationId);
         if (currentIndex !== -1) {
-          const nextIndex = (currentIndex + 1) % tabs.length;
-          claudeStore.switchConversation(tabs[nextIndex]);
+          const nextIndex = (currentIndex + 1) % tabOrder.length;
+          claudeStore.switchConversation(tabOrder[nextIndex]);
         }
       }
       // Ctrl/Cmd + Shift + Tab: Previous tab
       else if ((event.ctrlKey || event.metaKey) && event.key === "Tab" && event.shiftKey) {
         event.preventDefault();
-        const tabs = Array.from($conversations.keys());
-        const currentIndex = tabs.findIndex((id) => id === $activeConversationId);
+        const currentIndex = tabOrder.findIndex((id) => id === $activeConversationId);
         if (currentIndex !== -1) {
-          const prevIndex = (currentIndex - 1 + tabs.length) % tabs.length;
-          claudeStore.switchConversation(tabs[prevIndex]);
+          const prevIndex = (currentIndex - 1 + tabOrder.length) % tabOrder.length;
+          claudeStore.switchConversation(tabOrder[prevIndex]);
         }
       }
     }
@@ -190,15 +264,22 @@
 </script>
 
 <div
+  bind:this={tabsRef}
   class="terminal-tabs flex items-center gap-1 px-2 py-1 bg-[var(--bg-secondary)] border-b border-[var(--border-color)]"
 >
-  {#each Array.from($conversations.entries()) as [id, conversation] (id)}
+  {#each tabOrder
+    .filter((id) => $conversations.has(id))
+    .map((id) => ({ id, conversation: $conversations.get(id)! })) as { id, conversation } (id)}
     <div
-      class="tab-item group relative flex items-center px-3 py-1.5 rounded-t cursor-pointer transition-all
+      data-tab-id={id}
+      class="tab-item group relative flex items-center px-3 py-1.5 rounded-t transition-all
         {id === $activeConversationId
         ? 'bg-[var(--bg-terminal)] text-[var(--text-primary)] border-t border-l border-r border-[var(--border-color)]'
-        : 'bg-[var(--bg-tertiary)] text-[var(--text-secondary)] hover:bg-[var(--bg-terminal)]/50'}"
-      onclick={() => switchTab(id)}
+        : 'bg-[var(--bg-tertiary)] text-[var(--text-secondary)] hover:bg-[var(--bg-terminal)]/50'}
+        {dragOverId === id && draggedId !== id ? 'drag-over' : ''}
+        {draggedId === id ? 'dragging' : ''}"
+      onpointerdown={(e) => handlePointerDown(e, id)}
+      onclick={() => handleTabClick(id)}
       onkeydown={(e) => handleTabKeydown(id, e)}
       role="tab"
       tabindex={0}
@@ -211,7 +292,7 @@
           onblur={saveTabName}
           onkeydown={handleKeydown}
           onclick={(e) => e.stopPropagation()}
-          class="bg-transparent border-b border-[var(--border-color)] outline-none px-0 py-0 text-sm w-32"
+          class="bg-transparent border-b border-[var(--border-color)] outline-none px-0 py-0 text-sm w-32 select-text"
         />
       {:else}
         <div class="flex items-center gap-2">
@@ -296,5 +377,20 @@
 
   .tab-item {
     min-width: 100px;
+    cursor: grab;
+    touch-action: none;
+    user-select: none;
+  }
+
+  .tab-item:active {
+    cursor: grabbing;
+  }
+
+  .drag-over {
+    border-left: 2px solid var(--accent-primary);
+  }
+
+  .dragging {
+    opacity: 0.4;
   }
 </style>