starknet-mainnet

How far back this chain can be debugged

Stepping a transaction means re-executing it, and that needs the state the chain was in just before it ran. On this chain it is obtainable at block 501514 and above, and not below. THAT IS A LIMIT ON WHAT CAN BE RECORDED, not on what is published here. A transaction already recorded carries its own execution and steps from it for good; the boundary says that a transaction below it cannot be recorded NOW, because the state a replay would have to start from is not reachable by the pipeline that records this chain. The sentence below is that pipeline's own record of what it measured.

Of the 3 transactions recorded here, none steps at source level, which needs verified source and debug information for every contract a transaction ran, and 3 step one VM instruction at a time. A debug tier belongs to each recording rather than to the chain, so this counts what was recorded and promises nothing about the next transaction.

How that boundary was established, in the pipeline's own words: “prestate was obtainable from 501514 upward when this generation was captured, and not below it”

Recordings on this chain are executed from the cairo format. Each transaction's page states the granularity its steps are reported at: source lines where the contract's source was resolved, otherwise the format's own units.