Where do these 25 cells come from?
Every cell cites a specific file inside one of our three free starter kits — Claude Code, Cursor, or Copilot. The footer of each cell shows the kit name and file path. The kits are free ZIP downloads at
/,
/cursor-rules, and
/copilot-starter-kit; download any of them and you can verify the cell's source file exists exactly where it says.
What counts as a "win"?
Five marked cells along any row, column, or diagonal. There are 12 possible winning lines: 5 rows, 5 columns, and 2 diagonals. The banner above the grid lists every line you've completed. There's no scoring beyond the bingo itself — the point is honest self-audit, not a leaderboard.
Why isn't there a score?
A score implies a target. The point isn't "mark all 25" — most teams shouldn't. Different stacks need different habits. The point is to see which ones you've actually adopted, notice the obvious gaps, and decide what to ship next. A bingo line is a useful "you've built one consistent habit thread"; the rest is signal for what's missing.
How do I share my card?
Mark some cells. The "Share URL" box updates live with a 7-character hex code that encodes the 25 cells (1 = marked, 0 = empty). Copy and send. Anyone who opens it sees the same card. Your marks also persist in your browser via localStorage, so revisiting the page without a URL parameter shows your saved card.
How does the URL encoding work?
Each cell maps to a bit position 0–24 (cell 0 = top-left, cell 24 = bottom-right, reading left-to-right and top-to-bottom). The 25 bits pack into a single integer; we encode that integer as 7 lowercase hex characters. ?c=0000000 = empty card, ?c=1ffffff = every cell marked. The high 3 bits of the 28-bit hex value are unused (always 0) so the encoding is canonical.
Can I reset?
Yes — the "Reset card" button clears every cell and the share URL. Your localStorage entry is wiped too. There's also a "Mark every cell (yikes)" button — fills all 25 for the screenshot if you genuinely run that tight a shop.
Why these 25 specifically?
Each cell is a habit our three kits explicitly ship a template, snippet, or example for. We didn't generate the list from intuition — we walked the file tree of each kit and picked one habit per file, with five cells per quality area (setup, planning, quality gates, automation, per-stack). If a habit isn't in our kits, it's not on the card. Adding more would mean either shipping more kit content or admitting the cells aren't grounded.
Is the kit content reviewed?
Yes. Every kit on this site has been through adversarial review (Codex GPT) and a Node-based smoke test where applicable. The bingo cells reference the same files those reviews validate.
Does the page send any data?
No. The card is rendered, marked, encoded, and shared entirely client-side. No analytics, no telemetry, no third-party scripts beyond Google Fonts (CSS-only). Your marks stay in your browser unless you copy the share URL and send it somewhere yourself.