Draft lesson 204.3 — Identify smart contract interactions inside a blockchain event

[workshop-maybe]

SLT

204.3 — I can read a blockchain event and identify the smart contract interaction inside it.

Why it's unwritten

The Adder event structure for transactions is known (from 201/202 lessons and from cloning Adder during the 2026-04-16 audit), but the specific walk-through for identifying script interactions inside a `TransactionEvent` — spotting a script input, reading its redeemer, finding the matching witness — hasn't been written.

What's needed

• A real preprod transaction that spends a script UTxO (any DEX, any lock/unlock flow)
• A Go snippet that, given the `TransactionEvent` from Adder, walks inputs/witnesses/redeemers and surfaces:
  • which input was script-based
  • the script hash / policy ID involved
  • the redeemer contents (tag + data)
  • the datum (if inline or resolvable from reference inputs)

Blockers / dependencies

• Issue Adder event-type strings stale across Modules 201+202 (chainsync.* → input.*) #7 (Adder event-type rename) should be resolved first, so the lesson builds on correct filter/event setup
• Lesson 204.1 (decode datums/redeemers from CBOR) is a prerequisite and is shipped

Definition of done

• Lesson file at content/cardano-go-pbl/lessons/module-204/204.3-identify-contract-interactions.md
• Working Go code that parses a real preprod tx event and identifies the script interaction
• Explains the four places script metadata shows up in a transaction: inputs (script addresses), witnesses (scripts + redeemers), mint field (policy scripts), reference inputs (reference scripts)

Related

• Readiness rating: Needs Context
• Builds on 204.1 (CBOR decode) — shipped