Web3 engineering interview prep when AI proposes a transaction

Check what a wallet authorizes, what the chain confirms and what an indexer can report.

Try a Web3 interview

What companies say they’re looking for

01 Check what the wallet would authorize

“Transaction Check and Clear Signing show me on my Secure Screen exactly what I am approving.” (opens the source)

Ian Rogers, Chief Human Agency Officer, Ledger · Ledger Op3n, Paris · Ledger, Oct 15, 2026

Rogers describes reviewing a proposed payment separately. Compare the mock approval record with the AI summary.

Wallet engineering interviewWhat would this request authorize?Example

02 Separate early feedback from finality

“Flashblocks don’t replace finality - they layer a UX-level preconfirmation system on top of it.” (opens the source)

Yashvardhan Kukreja, Senior Software Engineer, OP Labs · Optimism, Sep 29, 2025

Kukreja distinguishes early feedback from finality. Check what belongs in the confirmed balance after the chain changes.

Blockchain infrastructure interviewWhat is confirmed after the chain changes?Example

03 Bind approvals to the change

“A timelock is an essential tool in blockchain governance. It takes transactions and delays their execution while making them visible to everyone.” (opens the source)

Alberto Cuesta Cañada, Former Staff Security Engineer, OP Labs · Optimism, Feb 19, 2026

Cuesta Cañada describes a delay before execution. Check the notice and approvals for the exact change in the case.

Protocol engineering interviewWhich version has approval?Example

04 Find the last complete block

“the system uses a high-water mark as a checkpoint to maintain the strict sequencing that certain components need.” (opens the source)

Bill Sahin, Linda Liu, Andrew Allen, Ning Wei and Xiaying Peng, Coinbase Engineering article authors · Coinbase, Jan 30, 2026

The Coinbase team describes a checkpoint for data that can arrive out of order. Find the first block the mock indexer cannot account for.

Blockchain indexing interviewWhere can the indexer claim completeness?Example

05 Check who can afford to verify

“However, this incentive isn't sufficient. We still need to encourage honest players to actually participate.” (opens the source)

Mofi Taiwo, Engineer, OP Labs, working on the OP Stack Proofs system · Optimism, Mar 6, 2024

Taiwo’s 2024 account explains why honest reviews need participants. Check whether a toy budget covers the planned review costs.

Protocol design interviewWill the reviewer budget cover the planned checks?Example

Sources

Ian Rogers, Chief Human Agency Officer, Ledger · Ledger Op3n, Paris, at the time. Ledger, “Ledger Agent Intent: A Single Interface for All Agent Requests”, Oct 15, 2026. Open the source. Checked against the published text.
Yashvardhan Kukreja, Senior Software Engineer, OP Labs, at the time. Optimism, “Flashblocks: Deep Dive - 250ms preconfirmations on OP Mainnet”, Sep 29, 2025. Open the source. Checked against the published text.
Alberto Cuesta Cañada, Former Staff Security Engineer, OP Labs, at the time. Optimism, “Timelock Guard”, Feb 19, 2026. Open the source. Checked against the published text.
Bill Sahin, Linda Liu, Andrew Allen, Ning Wei and Xiaying Peng, Coinbase Engineering article authors, at the time. Coinbase, “A Dedicated Architecture for Solana at Coinbase”, Jan 30, 2026. Open the source. Checked against the published text.
Mofi Taiwo, Engineer, OP Labs, working on the OP Stack Proofs system, at the time. Optimism, “Incentivizing honesty and participation in the OP Stack’s Fault Proof System”, Mar 6, 2024. Open the source. Checked against the published text.

Last reviewed Nov 11, 2026