feat(export): one-click PNG copy and download of the plan

Captures the full timeline (not just the scrolled viewport) by expanding
the grid to content width during render; clipboard write stays inside the
user gesture so Safari accepts it, with download as the documented fallback.

src/App.vue

@@ -1,9 +1,14 @@
 <script setup lang="ts">
+import { ref } from 'vue'
 import { useMacroplan } from './composables/useMacroplan'
+import { usePngExport, exportFilename } from './composables/usePngExport'
 import PlanEditor from './components/PlanEditor.vue'
 import MacroplanGrid from './components/MacroplanGrid.vue'
 
 const { source, plan, error, resetToSample } = useMacroplan()
+const { busy, toast, copyPng, downloadPng } = usePngExport()
+
+const exportRoot = ref<HTMLElement>()
 </script>
 
 <template>
@@ -16,6 +21,23 @@ const { source, plan, error, resetToSample } = useMacroplan()
           A week-granular, learning-oriented record of what we committed to deliver.
         </p>
       </div>
+      <button
+        class="btn btn-ghost btn-sm"
+        :disabled="!plan || busy"
+        title="Copy the rendered plan to the clipboard as a PNG"
+        @click="copyPng(exportRoot)"
+      >
+        <span v-if="busy" class="loading loading-spinner loading-xs"></span>
+        Copy PNG
+      </button>
+      <button
+        class="btn btn-ghost btn-sm"
+        :disabled="!plan || busy"
+        title="Download the rendered plan as a PNG"
+        @click="downloadPng(exportRoot, exportFilename(plan?.title ?? ''))"
+      >
+        Download
+      </button>
       <button class="btn btn-ghost btn-sm" @click="resetToSample">Reset to sample</button>
     </header>
 
@@ -30,10 +52,34 @@ const { source, plan, error, resetToSample } = useMacroplan()
       </section>
 
       <section class="min-h-0 flex-1 overflow-auto p-4">
-        <h2 v-if="plan" class="mb-3 text-sm font-semibold text-base-content/70">{{ plan.title }}</h2>
+        <div v-if="plan" ref="exportRoot" class="export-root">
-        <MacroplanGrid v-if="plan" :plan="plan" />
+          <h2 class="mb-3 text-sm font-semibold text-base-content/70">{{ plan.title }}</h2>
-        <p v-else class="text-sm text-base-content/60">Nothing to render yet — fix the source on the left.</p>
+          <MacroplanGrid :plan="plan" />
+        </div>
+        <p v-else class="text-sm text-base-content/60">
+          Nothing to render yet — fix the source on the left.
+        </p>
       </section>
     </main>
+
+    <div v-if="toast" class="toast toast-end">
+      <div class="alert" :class="toast.kind === 'ok' ? 'alert-success' : 'alert-error'">
+        <span>{{ toast.text }}</span>
+      </div>
+    </div>
   </div>
 </template>
+
+<style scoped>
+/* While exporting, grow to the timeline's full width and un-clip the grid so the
+   captured PNG shows every week column (not just the on-screen scroll window).
+   The base-200 frame + padding give the snapshot a little breathing room. */
+.export-root.exporting {
+  width: max-content;
+  padding: 1rem 1.25rem;
+  background: var(--color-base-200);
+}
+.export-root.exporting :deep(.macroplan) {
+  overflow: visible;
+}
+</style>

src/composables/usePngExport.ts

@@ -0,0 +1,85 @@
+import { ref } from 'vue'
+
+type Toast = { kind: 'ok' | 'err'; text: string } | null
+
+/** Slugified, stable download name derived from the plan title. */
+export function exportFilename(title: string): string {
+  const slug = title
+    .toLowerCase()
+    .trim()
+    .replace(/[^a-z0-9]+/g, '-')
+    .replace(/^-+|-+$/g, '')
+  return `macroplan-${slug || 'plan'}.png`
+}
+
+/**
+ * Client-side PNG export of a rendered Macroplan (C6 / F7). Captures the full
+ * grid — not just the scrolled viewport — by expanding the target to its
+ * content width for the duration of the render, then copies to the clipboard
+ * or downloads. html-to-image is dynamically imported so it stays out of the
+ * initial bundle (like Shiki in the editor).
+ */
+export function usePngExport() {
+  const busy = ref(false)
+  const toast = ref<Toast>(null)
+  let timer: ReturnType<typeof setTimeout> | undefined
+
+  function flash(kind: 'ok' | 'err', text: string) {
+    toast.value = { kind, text }
+    if (timer) clearTimeout(timer)
+    timer = setTimeout(() => (toast.value = null), 3000)
+  }
+
+  async function render(el: HTMLElement): Promise<Blob> {
+    const { toBlob } = await import('html-to-image')
+    // `exporting` expands the wrapper to max-content and un-clips the grid so the
+    // whole timeline is captured even when it scrolls horizontally on screen.
+    el.classList.add('exporting')
+    // reading layout flushes the class's style changes before we measure
+    const width = el.scrollWidth
+    const height = el.scrollHeight
+    try {
+      const blob = await toBlob(el, { width, height, pixelRatio: 2, cacheBust: true })
+      if (!blob) throw new Error('renderer returned no image')
+      return blob
+    } finally {
+      el.classList.remove('exporting')
+    }
+  }
+
+  async function copyPng(el?: HTMLElement | null) {
+    if (!el || busy.value) return
+    busy.value = true
+    try {
+      // ClipboardItem accepts a Promise<Blob>, so the async render stays inside
+      // the user-gesture window — Safari rejects a write started after an await.
+      await navigator.clipboard.write([new ClipboardItem({ 'image/png': render(el) })])
+      flash('ok', 'PNG copied to clipboard')
+    } catch {
+      flash('err', 'Couldn’t copy — use Download instead')
+    } finally {
+      busy.value = false
+    }
+  }
+
+  async function downloadPng(el?: HTMLElement | null, filename = 'macroplan.png') {
+    if (!el || busy.value) return
+    busy.value = true
+    try {
+      const blob = await render(el)
+      const url = URL.createObjectURL(blob)
+      const a = document.createElement('a')
+      a.href = url
+      a.download = filename
+      a.click()
+      URL.revokeObjectURL(url)
+      flash('ok', 'PNG downloaded')
+    } catch {
+      flash('err', 'Export failed — please retry')
+    } finally {
+      busy.value = false
+    }
+  }
+
+  return { busy, toast, copyPng, downloadPng }
+}