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Ogmios: represent 64-bit amounts as bigint with lossless JSON to avoid precision loss

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@emmanuel-musau is already working on this.

Since Sep 28, 2026.

Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
55/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Quiet
Tech stack
typescript
Domain
api, backend

Research direction

Start in packages/evolution/src/sdk/provider/internal/Ogmios.ts, focusing on the affected amount types and toOgmiosUTxOs, then inspect HttpUtils.postJson for request and response serialization. Trace the additionalUtxo path from KupmiosEffects.ts and KoiosEffect.ts. Done means the regression case preserves 2^64-1 and 2^53+1 as exact, unquoted JSON numbers and inbound amount parsing is lossless.

Written by the indexing model from the issue text.

Description

bug external-review

Summary

The Ogmios provider converts 64-bit Cardano amounts (lovelace and native-token quantities) with Number(...), but a JS number is exact only to 2^53-1. Cardano amounts are uint64, so any value above 2^53 is silently corrupted. Every other provider uses BigInt(...), and the SDK models Coin as Schema.BigInt up to 2^64-1, so this is an inconsistent defect. The corrupted values are sent to Ogmios as the additionalUtxo set during transaction evaluation, producing wrong ex-units/fees and on-chain rejection for transactions involving high-supply tokens. Fail closed: no fund loss, the tx is just rejected.

Affected

packages/evolution/src/sdk/provider/internal/Ogmios.ts: OgmiosAssets type (L128), Value type (L130-132), toOgmiosUTxOs Number(quantity) (L189) and Number(lovelace) (L216), inbound LovelaceAsset schema (L24-26), Delegation rewards/deposit (L118-119)
reached via: KupmiosEffects.ts:380 and KoiosEffect.ts:325 (additionalUtxo for evaluateTransaction)
transport: HttpUtils.postJson (bodyJson -> JSON.stringify on send; response.json -> JSON.parse on receive)
contrast (correct): Koios.ts:292/298, Maestro.ts toBigInt, Blockfrost.ts

Fix

Represent Ogmios amounts as bigint end to end (OgmiosAssets -> Record<string, Record<string, bigint>>, Value.ada.lovelace -> bigint, drop Number(...) in toOgmiosUTxOs).
Important: Ogmios encodes amounts as UNQUOTED JSON numbers (per the Ogmios v6 API, e.g. { "ada": { "lovelace": 1234 } }), so:

  • on send, a bigint cannot go through JSON.stringify; emit it as a bare JSON numeric literal via a lossless serializer (json-bigint style or a replacer that splices the integer), not as a quoted string (Ogmios will reject a string).
  • on receive, response.json uses standard JSON.parse which truncates above 2^53 before the schema, so any inbound amount field that can exceed 2^53 needs a big-int-aware parser, not just a BigInt schema. (The evaluate response is only ex-units, which are small, so the live issue is the send path; fix the receive path too for correctness on amount-bearing Ogmios queries.)

Regression test

  • given: a UTxO with token quantity 2^64-1 and lovelace 2^53+1, run toOgmiosUTxOs([utxo]) and serialize the additionalUtxo body the same way the request does
  • before fix: amounts are corrupted (2^64-1 -> 18446744073709552000, 2^53+1 -> 2^53)
  • after fix: the serialized payload contains the exact integers as unquoted JSON numbers, round-tripping unchanged

Must FAIL on main today and PASS after the fix.

Reference

GHSA-mrqw-3c7x-96mg

Dominant language
TypeScript
Stars
22
Forks
33
Avg merge
2d 12h
Merged PRs (30d)
36

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