The problem Shield solves

Everyday ETH holders keep crypto as savings not as a trade. Today ETH holders face a choice: sell all ETH to avoid a crash (and lose all future upside) or hold ETH and hope risking a large part of ETH holders’ savings overnight with no safety net. Buying insurance‑style protection like a put option can help,. It costs a recurring premium that is wasted most of the time it is not needed just like paying for insurance you never use.

What Shield Does

Shield lets ordinary ETH holders protect ETH holders’ savings from a crash at zero cost. Shield uses an idea from traditional finance called a collar now turned into an easy tool through Thetanuts’ on‑chain options protocol on Base.

Of paying an ongoing premium the user gives up a small amount of extreme upside that the user probably would not have captured anyway. That trade‑off pays for downside protection so the net cost of the whole Shield deal is close to zero.

How People Use It

Describe the goal in English, for example "I have 2 ETH I cannot afford to lose more than 10% and I am fine with capping my gains at 15% this month." No need to understand strike prices, expiries or options terminology.

Shield finds the deal automatically. Shield pulls pricing from Thetanuts’ market makers and calculates the exact floor (protection level) and cap (gains limit) where the cost cancels out to near zero.

See the deal explained in language before committing. "Your range is locked: floor $2,700 cap $3,350. Net cost: $2.”

Confirm and execute. Shield runs a safety check—verifying the contract, approval amount and transaction details—and only executes after confirmation directly on Base mainnet.

Why It Makes This Safer and Easier

No manual options knowledge required. The AI layer translates a plain‑language goal into the trade parameters and a deterministic solver and safety validator double‑check every number before any transaction is signed.

No recurring cost that goes to waste. Unlike insurance protection is funded by the trade itself not by an out‑of‑pocket premium paid every cycle.

No surprise. Forced sales. This is not a loan; there is no bot monitoring ratios. The only outcomes are: stay protected stay unaffected or sell at a price the user explicitly agreed to.

Transparent, on‑chain and verifiable. Every position is backed by collateralized options on Thetanuts not by a promise from a company. Anyone can verify it on Base.

Who It's For

Anyone holding ETH as savings who wants a safety net without becoming an options trader. People who have never touched DeFi derivatives but understand "I do not want to lose more, than X.”

Challenges we ran into

The most critical bug: clicking "Process Request" on the Protect page always returned "Failed to interpret goal".

The root cause was subtle. The Gemini API key in .env.local started with AQ. — a malformed key. Valid Gemini API keys start with AIza. Because the route called generateObject() unconditionally, it always threw a 500 with no fallback, leaving users stuck at the very first step.

The fix: We rewrote the API route with a two-tier strategy:

AI parsing is only attempted if a valid AIza... key is present.
A deterministic regex parser runs as the guaranteed fallback — no API key needed.
But even the regex parser had a bug: "protect 2 ETH below $3,900" returned desiredFloorPct: 2 instead of 3900. The generic number regex was greedily matching the ETH size (2) before reaching the floor price. We fixed it by anchoring the size regex to N ETH / N BTC patterns only.