What an L2 actually has to get right

“An L2 posts transactions to Ethereum and inherits its security” is the elevator pitch. Operating one is a longer conversation.

The parts that matter

Data availability — if the data behind a state root isn’t recoverable, users can’t exit. This is the whole game.
The bridge — the contract holding funds is the highest-value target on the stack. It should be boring, audited, and minimal.
Sequencing — someone orders transactions. Centralized sequencers are a pragmatic start and a decentralization to-do.
Proving — fraud proofs or validity proofs are what make the “inherits security” claim real rather than aspirational.

Working inside the Tokamak Network ecosystem, the launch tooling around these pieces is as important as the pieces themselves — most teams don’t fail at cryptography, they fail at operations.