fix

apps/x/apps/renderer/src/components/markdown-editor.tsx

@@ -10,6 +10,7 @@ import TaskItem from '@tiptap/extension-task-item'
 import { ImageUploadPlaceholderExtension, createImageUploadHandler } from '@/extensions/image-upload'
 import { TaskBlockExtension } from '@/extensions/task-block'
 import { TrackBlockExtension } from '@/extensions/track-block'
+import { TrackTargetExtension } from '@/extensions/track-target'
 import { ImageBlockExtension } from '@/extensions/image-block'
 import { EmbedBlockExtension } from '@/extensions/embed-block'
 import { ChartBlockExtension } from '@/extensions/chart-block'
@@ -43,6 +44,22 @@ function preprocessMarkdown(markdown: string): string {
   })
 }
 
+// Convert each `<!--track-target:ID-->...<!--/track-target:ID-->` region to a
+// placeholder HTML element that Tiptap's TrackTargetExtension parses into a
+// `trackTarget` node. Content is base64-encoded so any characters survive.
+// Without this step, tiptap-markdown strips the comment markers and leaves the
+// inner content as loose paragraphs, which then duplicates when the backend
+// re-inserts fresh markers around new content.
+function preprocessTrackTargets(md: string): string {
+  return md.replace(
+    /<!--track-target:([^\s>]+)-->\n?([\s\S]*?)\n?<!--\/track-target:\1-->/g,
+    (_match, id: string, content: string) => {
+      const b64 = btoa(unescape(encodeURIComponent(content)))
+      return `<div data-type="track-target" data-track-id="${id}" data-content="${b64}"></div>`
+    },
+  )
+}
+
 // Post-process to clean up any zero-width spaces in the output
 function postprocessMarkdown(markdown: string): string {
   // Remove lines that contain only the zero-width space marker
@@ -141,6 +158,13 @@ function blockToMarkdown(node: JsonNode): string {
       return serializeList(node, 0).join('\n')
     case 'taskBlock':
       return '```task\n' + (node.attrs?.data as string || '{}') + '\n```'
+    case 'trackBlock':
+      return '```track\n' + (node.attrs?.data as string || '') + '\n```'
+    case 'trackTarget': {
+      const id = (node.attrs?.trackId as string) ?? ''
+      const content = (node.attrs?.content as string) ?? ''
+      return `<!--track-target:${id}-->\n${content}\n<!--/track-target:${id}-->`
+    }
     case 'imageBlock':
       return '```image\n' + (node.attrs?.data as string || '{}') + '\n```'
     case 'embedBlock':
@@ -640,6 +664,7 @@ export const MarkdownEditor = forwardRef<MarkdownEditorHandle, MarkdownEditorPro
       ImageUploadPlaceholderExtension,
       TaskBlockExtension,
       TrackBlockExtension.configure({ notePath }),
+      TrackTargetExtension,
       ImageBlockExtension,
       EmbedBlockExtension,
       ChartBlockExtension,
@@ -1034,8 +1059,9 @@ export const MarkdownEditor = forwardRef<MarkdownEditorHandle, MarkdownEditorPro
       const normalizeForCompare = (s: string) => s.split('\n').map(line => line.trimEnd()).join('\n').trim()
       if (normalizeForCompare(currentContent) !== normalizeForCompare(content)) {
         isInternalUpdate.current = true
-        // Pre-process to preserve blank lines
-        const preprocessed = preprocessMarkdown(content)
+        // Pre-process to preserve blank lines, then wrap track-target comment
+        // regions into placeholder divs so TrackTargetExtension can pick them up.
+        const preprocessed = preprocessMarkdown(preprocessTrackTargets(content))
         // Treat tab-open content as baseline: do not add hydration to undo history.
         editor.chain().setMeta('addToHistory', false).setContent(preprocessed).run()
         isInternalUpdate.current = false

apps/x/apps/renderer/src/extensions/track-target.tsx

@@ -0,0 +1,117 @@
+import { mergeAttributes, Node } from '@tiptap/react'
+import { ReactNodeViewRenderer, NodeViewWrapper } from '@tiptap/react'
+import { Streamdown } from 'streamdown'
+
+/**
+ * TrackTargetExtension — a Tiptap atom node that owns a
+ *   <!--track-target:ID-->...<!--/track-target:ID-->
+ * region. Content is display-only; the backend is the sole writer.
+ *
+ * Parse path: `markdown-editor.tsx#preprocessTrackTargets` converts each
+ * comment-wrapped region into a placeholder
+ *   <div data-type="track-target" data-track-id="..." data-content="<base64>"></div>
+ * which the `parseHTML` rule below picks up.
+ *
+ * Serialize path: round-trips back to the exact comment-wrapped form via
+ * `addStorage().markdown.serialize` AND via the custom
+ * `blockToMarkdown` switch in `markdown-editor.tsx` (both save paths must
+ * handle it identically).
+ */
+
+// Unicode-safe base64 helpers — content may contain any char, including
+// emoji and CJK. btoa/atob alone only handle Latin-1.
+function encode(s: string): string {
+  return btoa(unescape(encodeURIComponent(s)))
+}
+
+function decode(s: string): string {
+  try {
+    return decodeURIComponent(escape(atob(s)))
+  } catch {
+    return ''
+  }
+}
+
+function TrackTargetView({ node }: {
+  node: { attrs: Record<string, unknown> }
+}) {
+  const trackId = (node.attrs.trackId as string) ?? ''
+  const content = (node.attrs.content as string) ?? ''
+
+  return (
+    <NodeViewWrapper
+      className="track-target-wrapper"
+      data-type="track-target"
+      data-track-id={trackId}
+    >
+      <div className="track-target-box" onMouseDown={(e) => e.stopPropagation()}>
+        {content.trim()
+          ? <Streamdown className="track-target-markdown">{content}</Streamdown>
+          : <span className="track-target-empty">No output yet — run the track to populate this area.</span>}
+      </div>
+    </NodeViewWrapper>
+  )
+}
+
+export const TrackTargetExtension = Node.create({
+  name: 'trackTarget',
+  group: 'block',
+  atom: true,
+  selectable: true,
+  draggable: false,
+
+  addAttributes() {
+    return {
+      trackId: { default: '' },
+      content: { default: '' },
+    }
+  },
+
+  parseHTML() {
+    return [
+      {
+        tag: 'div[data-type="track-target"]',
+        getAttrs(el) {
+          if (!(el instanceof HTMLElement)) return false
+          const trackId = el.getAttribute('data-track-id') ?? ''
+          const b64 = el.getAttribute('data-content') ?? ''
+          return { trackId, content: b64 ? decode(b64) : '' }
+        },
+      },
+    ]
+  },
+
+  renderHTML({ HTMLAttributes, node }: { HTMLAttributes: Record<string, unknown>; node: { attrs: Record<string, unknown> } }) {
+    return [
+      'div',
+      mergeAttributes(HTMLAttributes, {
+        'data-type': 'track-target',
+        'data-track-id': (node.attrs.trackId as string) ?? '',
+        'data-content': encode((node.attrs.content as string) ?? ''),
+      }),
+    ]
+  },
+
+  addNodeView() {
+    return ReactNodeViewRenderer(TrackTargetView)
+  },
+
+  addStorage() {
+    return {
+      markdown: {
+        serialize(
+          state: { write: (text: string) => void; closeBlock: (node: unknown) => void },
+          node: { attrs: { trackId: string; content: string } },
+        ) {
+          const id = node.attrs.trackId ?? ''
+          const content = node.attrs.content ?? ''
+          state.write(`<!--track-target:${id}-->\n${content}\n<!--/track-target:${id}-->`)
+          state.closeBlock(node)
+        },
+        parse: {
+          // handled by parseHTML after preprocessTrackTargets runs
+        },
+      },
+    }
+  },
+})

apps/x/apps/renderer/src/styles/editor.css

@@ -717,6 +717,42 @@
   outline-offset: 2px;
 }
 
+/* =============================================================
+   Track Target — rendered output region below a track chip.
+   Display-only; the backend is the sole writer.
+   ============================================================= */
+
+.tiptap-editor .ProseMirror .track-target-wrapper {
+  margin: 6px 0 10px 0;
+}
+
+.tiptap-editor .ProseMirror .track-target-box {
+  position: relative;
+  padding: 10px 12px 10px 16px;
+  border: 1px solid color-mix(in srgb, var(--foreground) 10%, transparent);
+  border-left: 3px solid color-mix(in srgb, var(--foreground) 30%, transparent);
+  border-radius: 8px;
+  background: color-mix(in srgb, var(--foreground) 3%, transparent);
+  user-select: text;
+  font-size: 13.5px;
+  line-height: 1.55;
+}
+
+.tiptap-editor .ProseMirror .track-target-wrapper.ProseMirror-selectednode .track-target-box {
+  outline: 2px solid color-mix(in srgb, var(--foreground) 30%, transparent);
+  outline-offset: 2px;
+}
+
+.tiptap-editor .ProseMirror .track-target-markdown > *:first-child { margin-top: 0; }
+.tiptap-editor .ProseMirror .track-target-markdown > *:last-child { margin-bottom: 0; }
+
+.tiptap-editor .ProseMirror .track-target-empty {
+  display: block;
+  font-size: 12px;
+  color: color-mix(in srgb, var(--foreground) 45%, transparent);
+  font-style: italic;
+}
+
 /* Shared block styles (image, embed, chart, table) */
 .tiptap-editor .ProseMirror .image-block-wrapper,
 .tiptap-editor .ProseMirror .embed-block-wrapper,