feat(indexer): sync LRN mint/burn events into scholar_balances - #1096
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Anuoluwapo25 merged 1 commit intoAug 30, 2026
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…onchain#1018) GET /api/scholars/leaderboard reads scholar_balances, but nothing wrote to it. LRN balances are now projected from learn_token's on-chain events. Balance updates are a non-idempotent read-modify-write, so deltas go through an append-only journal (lrn_balance_events) keyed by the Soroban event id and applied in the same statement that records them. Replays -- poller restarts, overlapping backfills, re-scanned ledger ranges -- collapse to a no-op instead of double-counting, and scholar_balances can be rebuilt exactly from SUM(delta) without re-reading the chain (Soroban RPC only retains a short window of events). - migration 035: journal table; widens lrn_balance to NUMERIC(40, 0), since 005's NUMERIC(30, 0) cannot hold every i128 the contract can emit and an overflow would stall the indexer on the offending ledger - db/scholar-balance-store: batch apply in one round trip, touching the balance table once per distinct address rather than once per event - lib/lrn-events: pure decoder for the topics the contract actually emits, `lrn_mint` (amount as the payload) and `lrn_burned` (map of from/amount). The issue text described GOVMinted/GOVBurned with value.fields, which does not match contracts/learn_token/src/lib.rs - services/scholar-balance-indexer: paginated sync holding O(page) memory, own checkpoint in indexer_state, clamps to the oldest retained ledger when a range has aged out of RPC - scripts/backfill-scholar-balances.ts: documented one-time replay, with --rebuild to recompute balances from the journal alone Also fixes two pre-existing bugs that made the poller a no-op: getLatestLedger returns Api.GetLatestLedgerResponse rather than a number, so Number(...) gave NaN and the batch loop never ran an iteration; the event-indexer test mocked the buggy shape and is corrected to the real one.
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Summary
GET /api/scholars/leaderboard reads scholar_balances, but nothing wrote to it. LRN balances are now projected from learn_token's on-chain events.
Balance updates are a non-idempotent read-modify-write, so deltas go through an append-only journal (lrn_balance_events) keyed by the Soroban event id and applied in the same statement that records them. Replays -- poller restarts, overlapping backfills, re-scanned ledger ranges -- collapse to a no-op instead of double-counting, and scholar_balances can be rebuilt exactly from SUM(delta) without re-reading the chain (Soroban RPC only retains a short window of events).
lrn_mint(amount as the payload) andlrn_burned(map of from/amount). The issue text described GOVMinted/GOVBurned with value.fields, which does not match contracts/learn_token/src/lib.rsAlso fixes two pre-existing bugs that made the poller a no-op: getLatestLedger returns Api.GetLatestLedgerResponse rather than a number, so Number(...) gave NaN and the batch loop never ran an iteration; the event-indexer test mocked the buggy shape and is corrected to the real one.
Closes #1018
Type of Change