Sardis v0.8.8: ERC-4337 Base Preview + Truth Alignment

v0.8.8 adds a real ERC-4337 implementation lane for design partners on Base Sepolia, introduces account_type parity across API and SDKs, and tightens public language around non-custodial posture.

v0.8.8 adds a real ERC-4337 implementation lane for design partners on Base Sepolia, introduces account_type parity across API and SDKs, and tightens public language around non-custodial posture and fiat partner rails.

Gasless Smart Wallets (ERC-4337)

The headline feature is a Base Sepolia preview lane for sponsored UserOperations. This lane is feature-flagged and fail-closed until bundler/paymaster and signer configuration are present.

New contracts: SardisSmartAccount, SardisSmartAccountFactory, SardisVerifyingPaymaster
Pimlico bundler/paymaster clients wired into execution runtime with explicit config gates
Wallet API and SDKs now support account_type="erc4337_v2"
Transfer responses now expose execution_path and user_op_hash
v1 wallets remain unchanged and fully supported
Current preview scope: Base Sepolia only

PostgreSQL Persistence for Cards & Ledger

We migrated all remaining in-memory stores to PostgreSQL. Card services (conversions, wallet mappings, offramp transactions) and the ledger engine now persist to Neon serverless PostgreSQL with full ACID guarantees.

PostgresUnifiedBalanceService: replaces in-memory USD balance tracking
PostgresAutoConversionService: replaces in-memory USDC/USD conversion records
PostgresOfframpService: replaces in-memory offramp transaction tracking
PostgresLedgerEngine: full-precision NUMERIC(38,18) entries with advisory locks
Alembic migration 015: 5 new tables with proper indexes

Security: Timestamped Webhook Verification

Onramper webhook validation now requires time-bounded signatures. We enforce a 5-minute replay tolerance window and reject old signatures to reduce replay attack risk.

Supports signature format t=<timestamp>,v1=<hmac> using timestamp.body payload signing
Supports legacy raw-body HMAC only when a timestamp header is present and valid
Rejects missing, invalid, and stale timestamps with explicit 401 responses

SDK and API Parity

Wallet and transfer surfaces now expose the same fields across API, Python SDK, TypeScript SDK, and MCP.

Create wallet now supports account_type (mpc_v1 or erc4337_v2)
Upgrade endpoint added: POST /api/v2/wallets/{id}/upgrade-smart-account
Transfer response includes execution_path and user_op_hash when applicable

Truth Alignment

We normalized docs and landing claims to match what is actually running:

Non-custodial wording now explicitly scoped to stablecoin live-MPC mode
Fiat rails wording now reflects regulated partner settlement/custody boundaries
Gasless wording now explicitly states Base Sepolia preview scope

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