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… rupansh/simul-txn
Make simulateTransaction safe for any user-submitted transaction. * Missing accounts: the SIMD-186 loader panicked on absent pubkeys. Now returns an empty System-owned default (matches Agave), so transactions that create new accounts can simulate. * Malformed transactions: added Agave-style sanitize that rejects zero/insufficient signatures, signatures > keys, out-of-range program/account indices, too many instructions (feature-gated), and the no-writable-signer case. All return SanitizeFailure. * Address lookup tables resolved on the simulate path so versioned transactions work end-to-end. * JSON wire format: TransactionError marshals to Agave's exact shape — bare string for unit variants, single-key object for tuple variants like InstructionError. * Rent sysvar load failure and fees.go no-fee-payer panics are now clean error returns. * Stake program: fix variable shadowing that silently dropped a rent sysvar read error.
* Pass-1 accountsdb fallback in loadAndValidateTxAcctsSimd186: per-block MemAccounts only holds accounts the block's txs reference, so System Program and other native programs are often missing on the simulate path. Fall back to slotCtx.AccountsDb before fabricating a default; matches the existing Pass-2 program fallback pattern. * IsTransactionAgeValid accountsdb fallback for durable-nonce txs: when a user simulates a nonce-based tx without replaceRecentBlockhash, the nonce account isn't in MemAccounts. Same fallback pattern as Pass-1 so the on-chain nonce state is consulted instead of returning BlockhashNotFound. * CalculateAndDeductTxFees: thread isSimulation through. Simulate returns the error cleanly to the RPC client; block-replay keeps the panic on a sanitize-bypass invariant break, preserving the loud operator-visible signal. * Sanitize-block comment trim in transaction_processing_pure.go.
* fees: assert simulate returns err while block-replay panics with diagnostic context on a missing fee payer. * sealevel: assert IsTransactionAgeValid returns true when the nonce account is in MemAccounts and false safely when both MemAccounts and AccountsDb are unavailable. * replay: Go fuzz test that drives random tx shapes through LoadAndExecuteTransaction and asserts no panics. Covers sanitize, loader, and fees branches.
Koro/simul txn fixes
- Strict response shape: all 14 RpcSimulateTransactionResult fields with correct nil/empty/null distinctions - Custom JSON-RPC errors: -32602 InvalidParams, -32016 MinContextSlotNotReached with structured contextSlot data - Inner instruction recording with stackHeight (Option<u32>), preserved across InstructionError paths via AssembleInnerInstructions - SPL Token + Token-2022 balance decoding with precise uiAmountString for high-decimals tokens (no float saturation) - Pre/post account snapshots for token balance pre-state - accounts.encoding base58/binary rejection - too-many-accounts cap uses post-ALT-resolved key count - ALT resolve before sigVerify so sigVerify-fail responses carry resolved loadedAddresses - PACKET_DATA_SIZE encoded-length cap matching Agave constants - Log + return-data clamping to spec limits (10KB / 1KB) Live-verified A-to-Z (48/48) against real mainnet CPI swaps, Token-2022 txs, ALT-using txs, vote txs, sigVerify-fail paths, and 50-parallel concurrent simulates. Block-replay running cleanly across 400+ slots with these changes.
feat(rpcserver): Agave-parity simulateTransaction wire format
smcio
approved these changes
May 7, 2026
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simulateTransaction rpc should have feature parity with agave (https://solana.com/docs/rpc/http/simulatetransaction)
quick js script to test: https://github.com/rupansh/solana-sim-txn/tree/master