feat: tab reordering via drag-n-drop.

Author: knightedcodemonkey

playwright/helpers/app-test-helpers.ts

@@ -139,6 +139,20 @@ export const openWorkspaceTab = async (page: Page, fileName: string) => {
   await page.getByRole('button', { name: pattern }).click()
 }
 
+export const reorderWorkspaceTabBefore = async (
+  page: Page,
+  { from, to }: { from: string; to: string },
+) => {
+  const source = page
+    .getByRole('button', { name: new RegExp(`^Open tab ${escapeRegex(from)}$`) })
+    .locator('..')
+  const target = page
+    .getByRole('button', { name: new RegExp(`^Open tab ${escapeRegex(to)}$`) })
+    .locator('..')
+
+  await source.dragTo(target)
+}
+
 export const setWorkspaceTabSource = async (
   page: Page,
   {

playwright/workspace-tabs.spec.ts

@@ -1,6 +1,7 @@
 import { expect, test } from '@playwright/test'
 import {
   addWorkspaceTab,
+  reorderWorkspaceTabBefore,
   setWorkspaceTabSource,
   waitForInitialRender,
 } from './helpers/app-test-helpers.js'
@@ -168,6 +169,59 @@ test('startup restores last active workspace tab after reload', async ({ page })
   await expect(page.locator('#editor-panel-styles')).toHaveAttribute('hidden', '')
 })
 
+test('workspace tab drag reorder persists across reload', async ({ page }) => {
+  await waitForInitialRender(page)
+
+  await addWorkspaceTab(page)
+  await addWorkspaceTab(page)
+
+  await reorderWorkspaceTabBefore(page, {
+    from: 'module-2.tsx',
+    to: 'App.tsx',
+  })
+
+  const orderedTabs = page.locator('#workspace-tabs-strip .workspace-tab__select')
+  await expect(orderedTabs.nth(0)).toHaveAttribute('aria-label', 'Open tab module-2.tsx')
+  await expect(orderedTabs.nth(1)).toHaveAttribute('aria-label', 'Open tab App.tsx')
+
+  await page.reload()
+  await waitForInitialRender(page)
+
+  const restoredTabs = page.locator('#workspace-tabs-strip .workspace-tab__select')
+  await expect(restoredTabs.nth(0)).toHaveAttribute('aria-label', 'Open tab module-2.tsx')
+  await expect(restoredTabs.nth(1)).toHaveAttribute('aria-label', 'Open tab App.tsx')
+})
+
+test('workspace tab drag onto itself keeps order unchanged', async ({ page }) => {
+  await waitForInitialRender(page)
+
+  await addWorkspaceTab(page)
+  await addWorkspaceTab(page)
+
+  const labelsBefore = await page
+    .locator('#workspace-tabs-strip .workspace-tab__select')
+    .evaluateAll(nodes =>
+      nodes
+        .map(node => node.getAttribute('aria-label'))
+        .filter((label): label is string => typeof label === 'string'),
+    )
+
+  await reorderWorkspaceTabBefore(page, {
+    from: 'App.tsx',
+    to: 'App.tsx',
+  })
+
+  const labelsAfter = await page
+    .locator('#workspace-tabs-strip .workspace-tab__select')
+    .evaluateAll(nodes =>
+      nodes
+        .map(node => node.getAttribute('aria-label'))
+        .filter((label): label is string => typeof label === 'string'),
+    )
+
+  expect(labelsAfter).toEqual(labelsBefore)
+})
+
 test('add menu can create styles tab while component tab is active', async ({ page }) => {
   await waitForInitialRender(page)
 

src/app.js

@@ -191,6 +191,9 @@ let workspaceTabRenameState = {
 let workspaceTabAddMenuOpen = false
 let isRenderingWorkspaceTabs = false
 let hasPendingWorkspaceTabsRender = false
+let draggedWorkspaceTabId = ''
+let dragOverWorkspaceTabId = ''
+let suppressWorkspaceTabClick = false
 const clipboardSupported = Boolean(navigator.clipboard?.writeText)
 const githubPrOpenIcon = {
   viewBox: '0 0 16 16',
@@ -1623,6 +1626,11 @@ const setWorkspaceTabAddMenuOpen = isOpen => {
   }
 }
 
+const clearWorkspaceTabDragState = () => {
+  draggedWorkspaceTabId = ''
+  dragOverWorkspaceTabId = ''
+}
+
 const renderWorkspaceTabs = () => {
   if (!(workspaceTabsStrip instanceof HTMLElement)) {
     return
@@ -1647,7 +1655,15 @@ const renderWorkspaceTabs = () => {
       tabContainer.className = 'workspace-tab'
       tabContainer.dataset.active = isActive ? 'true' : 'false'
       tabContainer.dataset.tabId = tab.id
+      tabContainer.draggable = true
+      tabContainer.dataset.dragOver =
+        dragOverWorkspaceTabId && dragOverWorkspaceTabId === tab.id ? 'true' : 'false'
       tabContainer.addEventListener('click', event => {
+        if (suppressWorkspaceTabClick) {
+          suppressWorkspaceTabClick = false
+          return
+        }
+
         const clickTarget = event.target
         if (!(clickTarget instanceof Element)) {
           return
@@ -1661,6 +1677,68 @@ const renderWorkspaceTabs = () => {
 
         setActiveWorkspaceTab(tab.id)
       })
+      tabContainer.addEventListener('dragstart', event => {
+        draggedWorkspaceTabId = tab.id
+        dragOverWorkspaceTabId = ''
+        suppressWorkspaceTabClick = true
+        if (event.dataTransfer) {
+          event.dataTransfer.effectAllowed = 'move'
+          event.dataTransfer.setData('text/plain', tab.id)
+        }
+      })
+      tabContainer.addEventListener('dragend', () => {
+        clearWorkspaceTabDragState()
+        queueMicrotask(() => {
+          suppressWorkspaceTabClick = false
+        })
+        renderWorkspaceTabs()
+      })
+      tabContainer.addEventListener('dragover', event => {
+        if (!draggedWorkspaceTabId || draggedWorkspaceTabId === tab.id) {
+          return
+        }
+
+        event.preventDefault()
+        if (event.dataTransfer) {
+          event.dataTransfer.dropEffect = 'move'
+        }
+
+        if (dragOverWorkspaceTabId !== tab.id) {
+          dragOverWorkspaceTabId = tab.id
+          tabContainer.dataset.dragOver = 'true'
+        }
+      })
+      tabContainer.addEventListener('dragleave', event => {
+        const relatedTarget = event.relatedTarget
+        if (relatedTarget instanceof Node && tabContainer.contains(relatedTarget)) {
+          return
+        }
+
+        if (dragOverWorkspaceTabId === tab.id) {
+          dragOverWorkspaceTabId = ''
+          tabContainer.dataset.dragOver = 'false'
+        }
+      })
+      tabContainer.addEventListener('drop', event => {
+        if (!draggedWorkspaceTabId || draggedWorkspaceTabId === tab.id) {
+          clearWorkspaceTabDragState()
+          renderWorkspaceTabs()
+          return
+        }
+
+        event.preventDefault()
+        persistActiveTabEditorContent()
+
+        const moved = workspaceTabsState.moveTabBefore(draggedWorkspaceTabId, tab.id)
+        clearWorkspaceTabDragState()
+        renderWorkspaceTabs()
+
+        if (!moved) {
+          return
+        }
+
+        queueWorkspaceSave()
+      })
 
       const isRenaming = workspaceTabRenameState.tabId === tab.id
       if (isRenaming) {

src/modules/workspace-tabs-state.js

@@ -213,6 +213,38 @@ export const createWorkspaceTabsState = ({ tabs = [], activeTabId, onChange } =
     return true
   }
 
+  const moveTabBefore = (
+    sourceTabId,
+    targetTabId,
+    { emitReason = 'moveTabBefore' } = {},
+  ) => {
+    const sourceId = toNonEmptyString(sourceTabId)
+    const targetId = toNonEmptyString(targetTabId)
+
+    if (
+      !sourceId ||
+      !targetId ||
+      sourceId === targetId ||
+      !tabsById.has(sourceId) ||
+      !tabsById.has(targetId)
+    ) {
+      return false
+    }
+
+    const sourceIndex = orderedIds.indexOf(sourceId)
+    const targetIndex = orderedIds.indexOf(targetId)
+    if (sourceIndex < 0 || targetIndex < 0 || sourceIndex === targetIndex) {
+      return false
+    }
+
+    orderedIds.splice(sourceIndex, 1)
+    const nextTargetIndex = orderedIds.indexOf(targetId)
+    orderedIds.splice(nextTargetIndex, 0, sourceId)
+
+    emit(emitReason)
+    return true
+  }
+
   replaceTabs({
     nextTabs: tabs,
     nextActiveTabId: activeTabId,
@@ -231,5 +263,6 @@ export const createWorkspaceTabsState = ({ tabs = [], activeTabId, onChange } =
     upsertTab,
     setActiveTab,
     removeTab,
+    moveTabBefore,
   }
 }

src/styles/panels-editor.css

@@ -253,6 +253,17 @@
   flex: 0 1 auto;
   min-width: 0;
   max-width: min(200px, 36vw);
+  cursor: grab;
+  border-top-color: var(--border-control);
+}
+
+.workspace-tab:active {
+  cursor: grabbing;
+}
+
+.workspace-tab[data-drag-over='true'] {
+  outline: 2px solid color-mix(in srgb, var(--accent) 72%, transparent);
+  outline-offset: -2px;
 }
 
 .workspace-tab[data-active='true'] {