A team board with fixed cards: drag and drop within and across columns with placeholders and animation, a detail panel, filters, search, undo, dark mode, and one-column-at-a-time scrolling on a phone.
Measured, not judged. Nothing here is a score.
| Measure | Claude Opus 5.5 | Claude Fable 5.1 | GPT-6 Astra | GPT-6.1 Sol |
|---|---|---|---|---|
| Time to build | 1h 40m | 45m 08s | 12m 31s | 14m 31s |
| AttemptsOnly an infrastructure failure (a rate limit or an outage) earns a retry. Every interrupted attempt is listed, and nothing from it is published. | 2Attempt 1: The Claude CLI could not reach the API ("Unable to connect to API: SSL certificate has expired") and ended the run after a few seconds. No index.html existed. Nothing from this attempt was published; the model got a fresh attempt once the API was reachable again. | 2Attempt 1: The Claude CLI could not reach the API ("Unable to connect to API: SSL certificate has expired") and ended the run after 30 minutes. No index.html existed. Nothing from this attempt was published; the model got a fresh attempt once the API was reachable again. | 1 | 1 |
| Delivered source | 113 KB | 80 KB | 62 KB | 64 KB |
| Files | 1 | 1 | 1 | 1 |
| Tokens in / outAs reported by each CLI. Tokenizers differ between vendors, so compare within a vendor. | 19.0M / 446k | 2.8M / 180k | 1.1M / 38k | 1.6M / 53k |
| Errors during recording | 0 | 0 | 0 | 0 |
| Video lengthUI recordings scroll at a fixed speed, so a longer page makes a longer video. | 26s | 26.6s | 25.7s | 26.5s |
Questions, not answers. The call is yours.
Drag two cards across columns, undo, filter Bug, open a card, close it, switch to dark mode; on the phone, swipe through the columns and open a card.
The same script runs on every build. Open any build live to judge sound, feel and anything a video can't show. Full method
Sent word for word to every model. Try it on your own favourite.
Design and build a kanban board for Northwind Labs, a (fictional) product team. DATA The board, its columns, people and cards are in ./data.json. Use exactly this data and embed it inline in index.html (the page must work when opened directly from disk, so do not fetch the file). Treat 2026-10-21 as today. FEATURES - Four columns, in this order and with exactly these titles: Backlog, In progress, Review, Done. Each column shows how many cards it holds. - Cards show the title, a coloured tag, the assignee's initials and the due date. Cards whose due date is before today are visibly flagged as overdue. - Drag and drop cards within a column and between columns, with the mouse and with touch: the dragged card follows the pointer, a placeholder shows where it will land, and the other cards animate out of the way. The order persists in localStorage and survives a reload. - Clicking a card opens a detail panel with the title, description, tag, assignee and due date, all editable, and a button labeled "Close". - A button labeled "Add card" at the bottom of each column creates a new card inline. - Filter chips above the board, labeled exactly: All, Bug, Feature, Design, Research. A search field filters cards by title as you type. - A button labeled "Undo" (also Ctrl/Cmd+Z) that reverts the last move or edit. - A dark-mode toggle button with aria-label="Toggle dark mode" and a complete, deliberately designed dark theme. - Responsive: at 390px wide the columns scroll horizontally one at a time (scroll snap), and everything works by touch. - Visual design is entirely up to you. Aim for the craft of a best-in-class product tool. DELIVERY RULES - Work autonomously. Nobody will answer questions, so make reasonable assumptions and keep going until the board is finished. - Deliver a single file, ./index.html, with all HTML, CSS, JavaScript and data inline. No build step, no frameworks or drag-and-drop libraries. - The only network resource allowed is fonts from Google Fonts. No other CDNs, no external images, no APIs. - The page must work when index.html is opened directly in a current version of Chrome, and when it is served over HTTP. It will be viewed at 1440x900 on desktop and 390x844 on a phone.