Welcome to Lego Land

Script · 0:00

Welcome to Lego Land. For the next hour we walk one toy park with seven districts, and every metaphor maps to a real protocol piece. The white bricks on screen open the actual specs, so nothing here is decoration.

Before we walk, the park rules. A single chain gets to pick about two of three things: scalability, security, decentralization. Make the blocks bigger and fewer people can afford to run a node, and you have quietly traded away decentralization. Ethereum stopped picking in 2020. The rollup roadmap leaves the base chain slow, scales the data it publishes, and settles everything on top. That is why the green slab lands first in this animation. Everything in this talk stacks on it, and the same green strip runs under every section of this page.

If asked why gas is expensive at all: block space is priced by EIP-1559. The queue at the gate is the fee market doing its job.

Script · 0:03

Quick hello before we walk. I'm Tanisha Katara, and parks like this one are my day job. Through KCG, my consulting firm, I work on governance design, tokenomics, economic design simulations and fee modeling. On the commercial side I do go-to-market and PMF analysis. In park terms: how the park decides, how it prices the rides, and how it fills with visitors.

Eleven-plus clients so far, every one through referral, and every one has renewed. They cover most of this park: L2s like the mini parks we'll visit, governments and policy think tanks, L1 dApps from the bazaar, a messaging protocol, and payments, which is where the robots come in later.

Enough about me. Grab a brick.

Script · 0:06

Let's lift the baseplate. The base chain kept exactly three jobs and moved everything else upstairs. The Consensus Hall puts events in order. The Archive keeps the data available. The Courtroom settles disputes, and its word is final.

Two mechanisms to know. First the toll booth. EIP-1559 splits every fee into a base fee, which is burned, and a small tip for the proposer. The base fee adjusts each block depending on how full blocks run, so the protocol sets the price rather than a bidding war. Second the blob cellar. EIP-4844 gives rollups data packets of roughly 128 kilobytes with their own fee market, pruned after about eighteen days. That is long enough for anyone to reconstruct and challenge what a rollup did, and short enough that nodes never carry the weight forever. The EVM never reads blob contents, only a commitment, which is why blob bytes cost so much less than calldata.

So yes, this layer is slow. Slow on purpose. It is a court anyone can audit.

If asked where the data goes after two weeks: the base layer guarantees the data was available while it mattered. Rollups, explorers and archives keep copies. Availability is not the same as permanent storage.

Script · 0:13

Now the mini parks, where people actually ride the rides. Two types, split by how they prove honesty. The trust-but-verify park posts its results and assumes they are fine. Anyone can file a fraud proof for about seven days, and one honest watcher is enough to catch cheating. The math-proof park ships a validity proof with every batch, and the base chain checks it in minutes. No waiting window. Pick your park by how you like your guarantees: a complaints window, or math.

Watch the train. Those cars are batches of compressed L2 transactions riding home as blobs. That is what makes tickets cost pennies.

Now the ladder, and this is the honest part. L2Beat grades rollups in stages. Stage 0 means the team can still override everything. Stage 1 means the proof system is live with a security council as backstop. Stage 2 means the council can only act on provable bugs. Same security as the main gate is fully true only at Stage 2, and most parks are still climbing. Say that plainly and builders will trust you.

Between parks: ERC-7683 lets a user sign the outcome they want and lets solvers race to deliver it. ERC-3770 puts the park's name in the address, so funds stop landing in the wrong one.

Script · 0:21

This is Grandma's bridge, and Grandma has one rule: she will never learn what a seed phrase is. Fair. The planks are what she experiences. Passkey login, gas paid for her, one tap instead of five, spending limits, and recovery through people she trusts.

The pipe below is what actually runs, and the purple dot is her single tap. Follow the numbers. Her tap becomes a UserOperation, which lives in its own mempool. A bundler collects a batch of these, fronts the gas, and calls one global contract called the EntryPoint. The EntryPoint asks her account to validate the operation by its own rules. Those rules can be a passkey signature, since RIP-7212 made those cheap to verify onchain, or a spending limit, or a session key for a game. A paymaster can pay her gas, so she never has to own ETH just to move. One tap in, one L1 transaction out.

For the millions of accounts that already exist, EIP-7702 is the retrofit ramp. An old account delegates to contract code and picks up the same powers without moving house. ERC-7579 and ERC-6900 standardize the snap-in modules, and ERC-1271 is how a contract signs.

This bridge is the second of Vitalik's three transitions. Remember it, because the robots at stop seven cross the same bridge.

Script · 0:29

The castle gates. The gatekeeper checks papers once, in the order a real sign-in happens, and then the park is yours. Name first: ENS resolves dev.eth in both directions. Then the signature: Sign-In with Ethereum, EIP-4361, is a structured message bound to the site's domain, so there is no password and nothing blind to phish. Then one person, not an army, which is personhood proof. Then the badges: soulbound tokens, ERC-5192, cannot be transferred, so a reputation cannot be bought. Last the receipts: attestations through EAS, where anyone can vouch for anything and apps can build on those claims.

Two more props. The backpack is ERC-6551, an NFT that owns its own wallet, so a game character can hold its own items. The cloak is stealth addresses, for receiving without the whole park watching.

The frame matters more than any single spec. We moved the bouncer to the door so there are no cameras inside. Verify at the perimeter, then leave people alone.

Script · 0:37

The bazaar, where this land coined the phrase money Legos years before I showed up with a deck full of bricks. Watch the coin do the party trick. It gets borrowed at the flash counter, swapped at the fountain, parked in the vault, and repaid before the bell. All inside one transaction. The bell is atomicity. If the repayment fails, the EVM reverts the entire trip. Not the lender loses money. The trip never happened. That is not trust, that is the runtime.

Why do the stalls snap together at all? ERC-20 is a tiny shared interface, and everything speaks it. The fountain prices by formula: two reserves, x times y stays constant, no order book and no merchant. The vault standard, ERC-4626, means an aggregator integrates deposit and withdraw once and every vault works. Permit, ERC-2612, turns the annoying approval step into a signature, so one transaction instead of two.

The bazaar's whole business model is that every stall trusts the same stud shape.

Script · 0:45

The commons. Fountains and roads, the things everyone uses and nobody owns, and the hard question of who pays for them. Look at the two bars. Same nine coins in both. Quadratic funding matches the square of the sum of square roots, so nine visitors giving one coin each pull a match of eighty-one, and one whale giving nine coins pulls nine. The math counts people, not money. Whales cannot buy the fountain.

The known attack is fake people. Sybils and collusion break quadratic funding, which is exactly why it leans on the personhood checks from the castle gates. The mechanisms connect.

Two more tools. RetroPGF flips the timing: build the road first, get the trophy once it carries traffic, because proven impact is easier to judge than promises. Hypercerts turn I-built-this-stretch-of-road into a claim you can hold and others can attest to.

If asked who fills the matching pool: protocol revenue, grants, ecosystem treasuries. The mechanism only decides how to split it.

Script · 0:51

The robot quarter, the newest district, and it reuses everything we just walked. Watch one full loop. Twelve seconds, five acts. The act bar and the numbered list light up in sync.

Act one: ClientBot reads Agent-42's passport. That is the ERC-8004 identity registry, live on mainnet since March, basically a pointer to the agent's card. Act two: the report card, the reputation registry, structured feedback from past jobs. Act three: the parcel crosses back. Work delivered. Act four is the payment. PayBot's tollgate answers with HTTP 402, Payment Required, a status code that sat reserved in the spec since 1997 because machines do not do checkout forms. ClientBot signs a USDC note using EIP-3009, gasless for the payer, x402 settles it, and the gate lifts on 200. Act five: ValidatorBot stamps the job into the validation registry.

Now the callback. Whose wallets are these? Grandma's bridge, 4337 and 7702. Where do their names live? The castle gates. The robots are just very fast tourists.

And the question I will leave hanging for the fireside: who governs a park where robots outnumber visitors?

Script · 0:57

Zoom out. There is the whole park in one frame. The bridge, the mini parks, the gate, the bazaar, the fountain, the tollbooth, and a few robots enjoying the evening. Every building here is clickable and takes you back to its stop. Notice what they all stand on. One green plate. We did not pick two out of three. We built up, and the base chain settles all of it.

If you want the single document that holds this talk together, it is Vitalik's Three Transitions. L2 scaling is the mini parks. Smart wallets are Grandma's bridge. Privacy and identity are the castle gates.

Here is the Monday morning ask. Pick one district. Click one stud. Read the spec tonight, and ship a toy this week. That is how every builder in this park started. Thank you.