Combine event decoding, rollback and failure context.
LET’S PICTURE IT
Solving a case means reconciling the surviving records with the abandoned attempts.
SEE IT FOR YOURSELF
From an emitted Transfer event to a receipt logStep 1 / 4
A token implementation may update balances and emit its standard Transfer event. State and the emitted record are related but distinct.
A token implementation may update balances and emit its standard Transfer event. State and the emitted record are related but distinct.A non-anonymous Transfer event uses the full thirty-two-byte Keccak-256 signature digest as topic zero, not a four-byte function selector.In the common ERC-20 shape, from and to occupy topics one and two. The raw value is a thirty-two-byte data word. Other standards can index fields differently.An application can decode receipt logs under the correct ABI. A matching signature does not establish that an unknown emitter is an honest token.
Animated local teaching model. No wallet, RPC or live blockchain data. Some labels and hashes are abbreviated for readability.
Challenge one: identify the layout
Given three topics and one data word, do not immediately label a log Transfer. First check the signature, indexed declaration, emitter and the non-indexed data schema.
Challenge two: apply rollback
A child emits then reverts, while its caller catches and emits a result. Identify which log survives before building a user-facing transaction narrative.
Challenge three: decode the failure
A payload begins 4e487b71 and contains code 11 in hex. Recognize the Panic schema and arithmetic category without claiming that the code identifies an exact source line.
Check your explanation
A complete answer states the chosen ABI, raw units, retained logs, failure propagation and what remains unknown. Clear limits are part of a correct technical explanation.
Inspect the example
event Transfer(address indexed from, address indexed to, uint256 value)
topic 0: 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef
topic 1: 0x0000000000000000000000000000000000000000000000000000000000000001
topic 2: 0x0000000000000000000000000000000000000000000000000000000000000002
data: 0x0000000000000000000000000000000000000000000000000000000000000064
Toy emitter; from address 1; to address 2; raw amount 100.
No token decimals or verified token identity are implied.
Separate failure fixture:
0x4e487b710000000000000000000000000000000000000000000000000000000000000011
Practice the log and failure independently; this is not a claim that both occurred in one real receipt.