feat(frontend): allow copying task details as Markdown

Add a button in the task detail actions panel that copies the task
as Markdown to the clipboard. The output format is:

  # Task title

  Description as markdown (links, bold, lists preserved)

Uses prosemirror-markdown (already bundled via @tiptap/pm) to convert
the HTML description to proper Markdown. No new dependencies added.

frontend/src/composables/useCopyToClipboard.ts

@@ -4,7 +4,7 @@ import {useI18n} from 'vue-i18n'
 export function useCopyToClipboard() {
 	const {t} = useI18n({useScope: 'global'})
 	
-	function fallbackCopyTextToClipboard(text: string) {
+	function fallbackCopyTextToClipboard(text: string): boolean {
 		const textArea = document.createElement('textarea')
 		textArea.value = text
 		
@@ -17,12 +17,13 @@ export function useCopyToClipboard() {
 		textArea.focus()
 		textArea.select()
 	
+		let success = false
 		try {
 			// NOTE: the execCommand is deprecated but as of 2022_09
 			// widely supported and works without https
-			const successful = document.execCommand('copy')
-			if (!successful) {
-				throw new Error()
+			success = document.execCommand('copy')
+			if (!success) {
+				error(t('misc.copyError'))
 			}
 			// eslint-disable-next-line @typescript-eslint/no-unused-vars
 		} catch (e) {
@@ -30,18 +31,20 @@ export function useCopyToClipboard() {
 		}
 	
 		document.body.removeChild(textArea)
+		return success
 	}
 	
-	return async (text: string) => {
+	return async (text: string): Promise<boolean> => {
 		if (!navigator.clipboard) {
-			fallbackCopyTextToClipboard(text)
-			return
+			return fallbackCopyTextToClipboard(text)
 		}
 		try {
 			await navigator.clipboard.writeText(text)
+			return true
 			// eslint-disable-next-line @typescript-eslint/no-unused-vars
 		} catch(e) {
 			error(t('misc.copyError'))
+			return false
 		}
 	}
 }

frontend/src/helpers/taskMarkdown.test.ts

@@ -0,0 +1,100 @@
+import {describe, expect, it} from 'vitest'
+
+import {formatTaskAsMarkdown} from './taskMarkdown'
+
+describe('formatTaskAsMarkdown', () => {
+	it('formats a task with title and description', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: 'Write release notes',
+			description: '<p>Summarize the changes for v1.0</p>',
+		})
+
+		expect(markdown).toBe('# Write release notes\n\nSummarize the changes for v1.0')
+	})
+
+	it('formats a task with title only when description is empty', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: 'Write release notes',
+			description: '',
+		})
+
+		expect(markdown).toBe('# Write release notes')
+	})
+
+	it('treats TipTap empty content as no description', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: 'Write release notes',
+			description: '<p></p>',
+		})
+
+		expect(markdown).toBe('# Write release notes')
+	})
+
+	it('converts links to markdown links', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: 'Check docs',
+			description: '<p>See <a href="https://vikunja.io/docs">the documentation</a> for details.</p>',
+		})
+
+		expect(markdown).toBe('# Check docs\n\nSee [the documentation](https://vikunja.io/docs) for details.')
+	})
+
+	it('converts bold and italic to markdown', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: 'Formatting test',
+			description: '<p>This is <strong>important</strong> and <em>urgent</em></p>',
+		})
+
+		expect(markdown).toBe('# Formatting test\n\nThis is **important** and *urgent*')
+	})
+
+	it('converts bullet lists to markdown', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: 'Shopping list',
+			description: '<ul><li><p>Milk</p></li><li><p>Eggs</p></li><li><p>Bread</p></li></ul>',
+		})
+
+		expect(markdown).toContain('* Milk')
+		expect(markdown).toContain('* Eggs')
+		expect(markdown).toContain('* Bread')
+	})
+
+	it('converts task lists with checked/unchecked state', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: 'Checklist',
+			description: '<ul data-type="taskList"><li data-type="taskItem" data-checked="true"><p>Done item</p></li><li data-type="taskItem" data-checked="false"><p>Todo item</p></li></ul>',
+		})
+
+		expect(markdown).toContain('[x] Done item')
+		expect(markdown).toContain('[ ] Todo item')
+	})
+
+	it('converts tables to pipe-separated rows', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: 'Table test',
+			description: '<table><tr><th>Name</th><th>Status</th></tr><tr><td>Task A</td><td>Done</td></tr><tr><td>Task B</td><td>Pending</td></tr></table>',
+		})
+
+		expect(markdown).toContain('Name | Status')
+		expect(markdown).toContain('Task A | Done')
+		expect(markdown).toContain('Task B | Pending')
+	})
+
+	it('preserves line breaks across paragraphs', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: 'Multi-paragraph',
+			description: '<p>First paragraph</p><p>Second paragraph</p>',
+		})
+
+		expect(markdown).toBe('# Multi-paragraph\n\nFirst paragraph\n\nSecond paragraph')
+	})
+
+	it('trims whitespace from the title', () => {
+		const markdown = formatTaskAsMarkdown({
+			title: '  Spaces around  ',
+			description: '',
+		})
+
+		expect(markdown).toBe('# Spaces around')
+	})
+})

frontend/src/helpers/taskMarkdown.ts

@@ -0,0 +1,92 @@
+import type {ITask} from '@/modelTypes/ITask'
+import {DOMParser as ProseMirrorDOMParser} from '@tiptap/pm/model'
+import {defaultMarkdownSerializer, MarkdownSerializer, schema} from '@tiptap/pm/markdown'
+
+type MarkdownTask = Pick<ITask, 'title' | 'description'>
+
+const pmDOMParser = ProseMirrorDOMParser.fromSchema(schema)
+
+// Non-strict mode: unknown nodes render their text content instead of throwing
+const markdownSerializer = new MarkdownSerializer(
+	defaultMarkdownSerializer.nodes,
+	defaultMarkdownSerializer.marks,
+	{strict: false},
+)
+
+// Placeholders for task checkboxes — replaced after serialization
+// because the serializer would escape the brackets
+const UNCHECKED_MARKER = '\u{FFFC}\u{2610}'
+const CHECKED_MARKER = '\u{FFFC}\u{2611}'
+
+/**
+ * Pre-processes TipTap HTML so the default ProseMirror schema can parse it.
+ */
+function preprocessHTML(html: string): string {
+	const doc = new DOMParser().parseFromString(html, 'text/html')
+
+	for (const item of doc.querySelectorAll('li[data-type="taskItem"]')) {
+		const checked = item.getAttribute('data-checked') === 'true'
+		const prefix = checked ? CHECKED_MARKER : UNCHECKED_MARKER
+		const firstBlock = item.querySelector('p, div')
+		if (firstBlock) {
+			firstBlock.insertBefore(doc.createTextNode(prefix), firstBlock.firstChild)
+		} else {
+			item.insertBefore(doc.createTextNode(prefix), item.firstChild)
+		}
+		item.removeAttribute('data-type')
+		item.removeAttribute('data-checked')
+	}
+
+	for (const list of doc.querySelectorAll('ul[data-type="taskList"]')) {
+		list.removeAttribute('data-type')
+	}
+
+	for (const table of doc.querySelectorAll('table')) {
+		const rows: string[] = []
+		for (const tr of table.querySelectorAll('tr')) {
+			const cells: string[] = []
+			for (const cell of tr.querySelectorAll('td, th')) {
+				cells.push((cell.textContent || '').trim())
+			}
+			rows.push(cells.join(' | '))
+		}
+		const replacement = doc.createElement('div')
+		for (const row of rows) {
+			const p = doc.createElement('p')
+			p.textContent = row
+			replacement.appendChild(p)
+		}
+		table.replaceWith(replacement)
+	}
+
+	return doc.body.innerHTML
+}
+
+function htmlToMarkdown(html: string): string {
+	if (!html || html === '<p></p>') {
+		return ''
+	}
+
+	const preprocessed = preprocessHTML(html)
+	const dom = new DOMParser().parseFromString(preprocessed, 'text/html')
+	const doc = pmDOMParser.parse(dom.body)
+
+	return markdownSerializer.serialize(doc)
+		.replace(new RegExp(UNCHECKED_MARKER, 'g'), '[ ] ')
+		.replace(new RegExp(CHECKED_MARKER, 'g'), '[x] ')
+		.trim()
+}
+
+/**
+ * Format a task as Markdown (title as heading + description).
+ */
+export function formatTaskAsMarkdown(task: MarkdownTask): string {
+	const parts: string[] = [`# ${task.title.trim()}`]
+
+	const description = htmlToMarkdown(task.description)
+	if (description) {
+		parts.push('', description)
+	}
+
+	return parts.join('\n')
+}

frontend/src/i18n/lang/en.json

@@ -965,6 +965,7 @@
       "updateSuccess": "The task was saved successfully.",
       "deleteSuccess": "The task has been deleted successfully.",
       "duplicateSuccess": "The task was duplicated successfully.",
+      "copyMarkdownSuccess": "The task was copied as Markdown.",
       "noBucket": "No bucket",
       "bucketChangedSuccess": "The task bucket has been changed successfully.",
       "belongsToProject": "This task belongs to project '{project}'",
@@ -996,6 +997,7 @@
         "relatedTasks": "Add Relation",
         "moveProject": "Move",
         "duplicate": "Duplicate",
+        "copyMarkdown": "Copy as Markdown",
         "color": "Set Color",
         "delete": "Delete",
         "favorite": "Add to Favorites",

frontend/src/views/tasks/TaskDetailView.vue

@@ -534,6 +534,13 @@
 						>
 							{{ $t('task.detail.actions.duplicate') }}
 						</XButton>
+						<XButton
+							variant="secondary"
+							icon="paste"
+							@click="copyTaskAsMarkdown"
+						>
+							{{ $t('task.detail.actions.copyMarkdown') }}
+						</XButton>
 
 						<span class="action-heading">{{ $t('task.detail.dateAndTime') }}</span>
 
@@ -685,6 +692,8 @@ import {useBaseStore} from '@/stores/base'
 
 import {useTitle} from '@/composables/useTitle'
 import {useTaskDetailShortcuts} from '@/composables/useTaskDetailShortcuts'
+import {useCopyToClipboard} from '@/composables/useCopyToClipboard'
+import {formatTaskAsMarkdown} from '@/helpers/taskMarkdown'
 
 import {success} from '@/message'
 import type {Action as MessageAction} from '@/message'
@@ -701,6 +710,7 @@ defineEmits<{
 const router = useRouter()
 const route = useRoute()
 const {t} = useI18n({useScope: 'global'})
+const copy = useCopyToClipboard()
 
 const projectStore = useProjectStore()
 const taskStore = useTaskStore()
@@ -1146,6 +1156,13 @@ async function duplicateCurrentTask() {
 	}
 }
 
+async function copyTaskAsMarkdown() {
+	const copied = await copy(formatTaskAsMarkdown(task.value))
+	if (copied) {
+		success({message: t('task.detail.copyMarkdownSuccess')})
+	}
+}
+
 async function setPriority(priority: Priority) {
 	const newTask: ITask = {
 		...task.value,