LEVEL 02 · Intermediate
Design clients, account models, program interactions, and meaningful tests.
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SIX STEPS · BUILD ONE IDEA AT A TIME
Design a client that distinguishes missing, stale, and failed data.
Write pseudocode for the viewer and tests for a delayed old-wallet response. Show an error message that keeps the last successful observation visibly labeled as stale.
Model an instruction and its required accounts.
Design a learner-record update for one wallet and one course revision. State the account owner, canonical PDA seeds, stored authority field, signer, writable accounts, revision ch…
Design deterministic state addresses without inventing private keys.
Specify the exact seed byte schema for one badge per learner per level per curriculum revision. Include a fixed domain prefix, fixed-width wallet bytes, normalized level and revis…
Trace authority across a composed instruction.
Draw the CPI boundary and annotate its exact signer and writable accounts. Then use a source account with owner PDA A and an approved delegate with allowance 80: determine whether…
Translate invariants into constraints and executable checks.
Write a test matrix for a credential instruction with six hostile inputs. For each, state the expected rejection and the account state that must remain unchanged.
Design and test a client-to-program escrow workflow with explicit account, authority, and recovery rules.
Produce a token escrow package containing a state diagram, canonical PDA seeds, account constraints, client signing flow, five adversarial test cases, and a recovery report for a …