BUILD NOTHING

Stake MON on not vibecoding. A Claude Code skill snitches on you if you break.

Submitted to Monad Spark - a hackathon about building anything.

The problem (mine, specifically)

I ship across a dozen ecosystems and I have not written a function without Claude Code in months. Half of crypto twitter is joking about forgetting how to code. The jokes stopped being jokes. There was no way to quit that had teeth - a promise to yourself costs nothing to break.

BUILD NOTHING makes it cost something, publicly.

How it works

1. Vow. Call commit(duration, snitchAddress) with your stake (1-30 days, max 100 MON). One active vow per address.
2. The snitch. A Claude Code skill installs two things on your machine:
   • a SessionStart hook: the moment a Claude Code session starts, a dust-funded burner sends relapse(vowId). Immediate, public, permanent.
   • a daily cron heartbeat(vowId): proof the snitch is alive.
3. The math. The contract stores only lastBeat and a running maxGap. Any gap over 48h = slashed (killing the snitch is confessing). A relapse ping = slashed. Survive the full window = your stake back plus a pro-rata share of everything slashed from your weekly cohort.
4. Epochs. Vows settle in weekly cohorts. If nobody in a cohort survives, the pot rolls into a jackpot inherited by the next cohort's survivors. Donations to the contract seed the jackpot.
5. The receipts. Share cards render your streak as tally marks on a wall: I BUILT NOTHING FOR 96 HOURS, stamped CLEAN - or your count crossed out in red, stamped RELAPSED, with exactly how long you lasted. Both are worth posting. The relapse card possibly more.

Threat model, honestly

• Tamper-evident, not tamper-proof. Deleting the snitch kills the heartbeat and auto-slashes you. Surgically removing only the hook while keeping the cron alive defeats the system. That is premeditated fraud against a small-stakes game between consenting degens; the 100 MON stake cap is sized for exactly this trust level.
• Scope. The snitch watches Claude Code on the machine it's installed on. It does not watch claude.ai in a browser or your second laptop. The enforced vow is "no vibecoding here"; the rest is honor and cohort pressure.
• Offline grace. 48h heartbeat gap allowance: a weekend away is safe, a week offline is indistinguishable from tampering and will be slashed.
• Randomless. No oracles, no VRF, no external dependencies. Every resolution path is a state check the chain performs on itself.

Why Monad

Heartbeats are a transaction a day per participant, relapses and dust funding more. At Monad gas prices the entire surveillance apparatus runs on cents - a burner funded with 0.05 MON snitches for a month. The economics of self-betrayal have never been this affordable.

Live deployment

• App: https://buildnothing.fun
• Network: Monad Mainnet (chainId 143)
• Contract: 0x380b02992E2E0Be93eA31841a0E911D85DE77842
• Source verification: full match on MonadVision/Sourcify https://sourcify-api-monad.blockvision.org/repository/contracts/full_match/143/0x380b02992E2E0Be93eA31841a0E911D85DE77842/metadata.json

How to use

The web app handles the on-chain vow. The local snitch handles proof that the vow was not bypassed.

1. Generate a snitch burner.

   node skill/scripts/setup.mjs

   This creates ~/.buildnothing/burner.json and prints a burner address. Fund that burner with a small amount of MON for gas, for example 0.05 MON. The burner is not your stake wallet; it only sends heartbeat() and relapse() transactions.

2. Take the vow on the website.

   Open https://buildnothing.fun, choose duration and stake, paste the burner address as the snitch address, then click Connect wallet & commit. The stake is paid from your normal wallet.

3. Arm the snitch.

   After the transaction confirms, use the returned vow id:

   BN_CONTRACT=0x380b02992E2E0Be93eA31841a0E911D85DE77842 node skill/scripts/setup.mjs --arm <vowId>

   Arming installs a Claude Code SessionStart hook, installs a daily heartbeat cron/launchd job, and sends the first heartbeat immediately.

4. Do not open Claude Code until the vow ends.

   Opening Claude Code sends relapse(vowId) from the burner. Killing the heartbeat for more than 48 hours lets the contract slash the vow as tampered.

5. Check or share a vow.

   Use the Check a vow form on the website with either the vow id or wallet address. The page reads Monad Mainnet live state and can generate a share card.

To clean up after a demo:

node skill/scripts/setup.mjs --disarm

If a vow is still active, disarming intentionally reports a relapse first.

Judge walkthrough

For a fast review, judges can:

1. Open https://buildnothing.fun and inspect the live contract link in the footer.
2. Check vow 1 in the Check a vow form.
3. Review the verified contract source using the Live deployment link above.
4. Run forge test locally; the contract test suite should pass 11/11.

Repo layout

• src/BuildNothing.sol - the contract (11/11 tests passing)
• test/BuildNothing.t.sol - full lifecycle: survive, relapse, tamper, offline grace, rollover jackpot, late-resolve ratio freeze
• skill/ - the Claude Code skill: SKILL.md, setup (arm/disarm), snitch runtime
• cards/ - share card generator (SVG -> PNG)
• web/ - vow page, cohort leaderboard, card sharing

Roadmap

The current version is intentionally honest rather than frictionless: a vow only has teeth once the local snitch is armed, and that still requires a few manual steps. The next milestone is to keep the same threat model while making the setup feel closer to "stake MON and wait".

1. Local snitch companion. Ship a tiny localhost helper that the user runs once. It generates the burner locally, stores the private key in ~/.buildnothing, and exposes only a narrow API to the website: status, generate, arm, disarm, and heartbeat.
2. Safe website pairing. Add a Connect local snitch flow. The helper prints a pairing code, the user enters it on the site, and the site receives only the burner address and status - never the burner private key.
3. Auto-fill and auto-arm. After pairing, the site fills the snitch address, the user stakes from their normal wallet, and the helper arms the returned vow id automatically.
4. Security guardrails. The helper must listen only on 127.0.0.1, accept only the official origin, require the pairing token for side effects, and refuse arbitrary transactions. It may sign only heartbeat(vowId) and relapse(vowId) for the deployed BuildNothing contract after verifying vow.snitch == burnerAddress.
5. Clear product split. Keep the manual CLI as a transparent fallback. The website should explain the core rule plainly: no snitch, no proof. The main wallet stays in Rabby/Phantom; the snitch burner only holds gas dust.
6. Non-crypto charity mode. Add a walletless path for users who do not hold MON. Instead of calling it a stake, frame it as a card-based charity pledge: the user chooses a nonprofit, chooses an amount, and a relapse triggers a donation workflow through Pledge. The UI must be explicit that donations are processed by Pledge and disbursed to nonprofits through Pledge's payout schedule, not instantly routed on-chain. Crypto users keep the trustless MON stake mode; non-crypto users get a familiar card flow with charitable consequences.

Deploy

forge script script/Deploy.s.sol --rpc-url $MONAD_RPC --private-key $PK --broadcast

Then set BN_CONTRACT in the skill environment and take your own vow. Vow #1 belongs to the author. The repo you are reading was the last thing she was allowed to build.