Rollups, Data Availability and L2
Introduction
Rollups separate execution and ordering from settlement while publishing data and state claims to another layer. This branch traces that full lifecycle rather than calling every low-fee chain an L2.
Why It Matters
“Confirmed on L2” can mean sequencer acceptance, batch publication, proof/fraud window status, or L1 finality. Upgrades, data availability, forced inclusion, withdrawals, and bridge contracts often dominate the real trust model.
Mental Model
Follow one transaction through submission, sequencing, L2 execution, batch/state commitment, data publication, proof or challenge, L1 acceptance, and withdrawal. Label each state unsafe, safe, or finalized only according to that system's documented semantics.
Questions This Branch Answers
- Who orders, proves, challenges, publishes, and upgrades the system?
- Can users reconstruct state and force transactions or exits?
- Which event creates the settlement claim exposed to applications?
Scope
Optimistic/validity rollups, sequencers, batches/commitments, calldata/blobs/DA, fraud and validity proofs, forced inclusion/withdrawals/escape, upgrade keys/stages, and OP Stack/Arbitrum/ZK/appchain contrasts.
Out of Scope
Throughput marketing, token economics, full rollup-node operation, blanket security rankings, and treating every sidechain or validium as equivalent to a rollup with on-chain DA.
Dependencies
consensus/finality/DA, execution, and upgrade authority.
Candidate Note Roadmap
rollup-execution-settlement-and-da— Draw the complete transaction and trust lifecycle.optimistic-rollups-and-fraud-proofs— Model assertions, challenge windows, and dispute assumptions.zk-rollups-and-validity-proofs— Bind execution claims to proof verification and data access.sequencers-batches-and-state-commitments— Track ordering, soft confirmations, posting, and commitment states.calldata-blobs-and-data-availability— Compare publication channels, retention, and reconstruction.forced-inclusion-withdrawals-and-escape-hatches— Exercise censorship and failure recovery paths.upgrade-keys-stages-and-decentralization— Inventory privileged control and progressive trust claims.op-stack-arbitrum-zk-and-appchain-contrasts— Compare concrete architectures without collapsing differences.
Future Project
Deploy Statecraft to Anvil plus a controlled OP Stack environment and a second simulated L2; expose unsafe/safe/finalized states and run sequencer, prover, data, and withdrawal failure drills.
Initial Invariants
User-visible status never overstates finality; batch/commitment identifiers bind the intended chain and state; withdrawal eligibility follows the documented proof/challenge path; recovery tests keep pending and finalized state distinct.
Initial Threat Model
Sequencer censorship/outage, unavailable data, invalid commitments, proof-system/prover failure, L1 reorg, admin or upgrade capture, dishonest RPCs, bridge delays, forced-inclusion failure, and misleading cross-domain status.
Primary Sources
Ethereum rollup documentation, OP Stack and Arbitrum specifications, zk-rollup primary docs, L2BEAT methodology, and links in SOURCES.md.
Connects to: bridges, validity proofs, and L2 operations.