How to Make UTXO a Programmable Computing Layer Without Adding Another EVM Layer to Bitcoin

For Developers: UTXO State Transfer, Parallel Validation, Open Code and Audit Re-examination.

Bitcoin's UTXO excels at answering one question: who has the right to spend this output? However, complex applications require further inquiries: where does this output come from, what must the next transaction look like, how does the state continue, and can different contracts execute simultaneously? Most networks choose to add an execution environment outside of Bitcoin, while TBC brings the question back to UTXO itself.

Whether this route is valid should not be determined by slogans. Code, development tools, benchmark methods, and audit records are the answers that technical readers need to check.

1. The Challenges of Bitcoin's Programmability: It's Not Just a Few Missing Opcodes

Bitcoin Script intentionally maintains restraint. A UTXO carries a clear amount and spending conditions, generating new outputs when consumed; nodes verify signatures and scripts without needing to maintain a global account state like EVM. This model has clear boundaries and allows unrelated outputs to be verified in parallel.

The difficulty arises when the state needs to continue across transactions. AMMs need to remember reserve amounts, token contracts must verify issuance and transfer rules, NFTs need to maintain ownership and metadata, and on-chain order books must handle the relationships between orders, trades, and settlements. The original script can constrain current spending but is inconvenient for verifying a continuously evolving business state.

The mainstream approach is to move complex logic to sidechains, Rollups, or another virtual machine. These solutions have formed mature development environments but also introduce new boundaries: assets may need bridging, states must be synchronized across different systems, and execution layers must establish their own validation and upgrade mechanisms. The problem has not disappeared; it has simply shifted from "how UTXO expresses state" to "how multiple systems maintain consistency."

2. TBC's Choice: Let Transactions Carry Their Own State

TBC retains SHA256 PoW and the UTXO route while introducing TuringTXID, TuringContract, and BVM. It does not centralize contract states into a global account tree but allows states to exist within contract UTXOs and their subsequent transactions: old outputs are consumed, and new outputs carry the updated state forward.

The key is not to rename UTXO as accounts but to enable scripts to verify the relationship between "parent" and "child". This way, contract rules can be passed along with transactions, and each state change remains an independently verifiable UTXO transaction.

This also delineates a clear boundary: TBC is an independent public chain adopting a Bitcoin-style architecture, not merely inserting contracts directly into the BTC mainnet. What it aims to prove is whether native UTXO execution can become an alternative engineering choice outside of the account model.

3. Three Changes to Connect Isolated Outputs into a Verifiable State Machine

1. TuringTXID: Only Carrying the Data Needed for Verification

Ordinary TXIDs compress the entire transaction into a single hash. If a contract only wants to verify a certain field in historical transactions, it often still needs more context. The TuringTXID described in the TBC white paper adopts a layered hash, allowing different parts of the transaction to have composable summaries; irrelevant data can be trimmed while key fields can still be verified along the hash path.

The result is not "free on-chain data" but rather that contracts do not have to repeatedly transport entire ancestor transactions when verifying local history. For UTXO contracts with states persisting over multiple generations, this directly impacts script size, network transmission, and node verification costs.

2. OP_PUSH_META and OP_PARTIAL_HASH: Checking Transaction Context

OP_PUSH_META sends transaction metadata such as current inputs, previous outputs, and output summaries into the script, allowing the script to see the transaction structure it is verifying. OP_PARTIAL_HASH is used to continue calculating hashes on segmented data, enabling the script to reconstruct and verify key summaries.

With both working together, contracts can constrain subsequent outputs: new states must continue to use specified scripts, assets can only move according to preset rules, and certain fields must maintain relationships with previous states. Here, "memory" is not an off-chain database but rather the continuity of state carried by each generation of UTXO and re-verified by the next spending.

3. BVM and Parallel Validation: Isolating States to Reduce Unrelated Competition

In a global account state machine, if multiple transactions read and write the same state, the execution order will affect the results. TBC breaks contract states into different UTXOs, and unrelated inputs do not share write points, allowing nodes to allocate them for verification across multiple computing cores.

This does not mean that all contracts are naturally infinitely parallel. Contention for the same UTXO, accessing the same hot pool, or forming dependent transactions must still be ordered; disk I/O, network propagation, and signature verification can also become bottlenecks. The publicly stated 13,000+ TPS for TBC is a performance metric for the project, not a universal constant divorced from transaction types and hardware environments; the million-level throughput of ParaUTXO should still be understood as a research and development goal, not an already realized mainnet capability.

4. Geeks Look Beyond Architecture Diagrams to See If It Can Run

The most direct public entry for TBC is TBCNODE and tbc-contract. The former provides full node code, while the latter is a smart contract SDK aimed at JavaScript developers. The official quick start installation command is just one line:

npm i tbc-contract

The SDK already covers on-chain data queries, UTXO retrieval, transaction assembly, signing, and broadcasting, and provides workflows for MultiSig, NFTs, FTs, and Pools. Developers can first generate transactions on the testnet, check the raw transaction structure, and then decide whether to enter more complex contract scenarios. The tbc-lib-js and wallet connection components provide lower-level transaction and signing capabilities.

This is a step forward from merely releasing a white paper, but there is still a gap to a mature development platform. The consistency of documentation, reproducible benchmarks, local debugging, indexing services, testing frameworks, and third-party tutorials all need to be further supplemented. For geeks, these shortcomings are not negative information that should be hidden but rather test questions to determine whether a network welcomes external developer testing.

5. Two Node Audits Prove the Repair Process Rather Than Absolute Security

In August 2026, CertiK and SlowMist publicly released the audit records for TBCNODE. CertiK's manual review covered 21 files, recording 11 findings, of which 9 were marked as Resolved, 2 as Acknowledged; there were no Critical issues, and 1 Major issue was resolved. SlowMist conducted a white-box audit on TBCNODE v3.3.1, also recording 11 findings, with an overall conclusion of Low Risk, and the only High issue marked as Fixed.

The classification methods of the two reports differ, so they cannot simply be summed up as 22 independent vulnerabilities. A more meaningful fact is that the audit object falls on the core node software, with problems, versions, and handling statuses publicly recorded. Professional readers can check which issues have been resolved and which risks have been acknowledged by the project team.

Audits are also not a permanent security guarantee. They only cover specific submissions, agreed scopes, and time points, and cannot automatically ensure the performance of subsequent versions, node configurations, key management, or real load operations. If TBC wants to continue accumulating this advantage, it needs to bind audit submissions, repair matrices, retests, and version releases.

6. What TBC Truly Needs to Win Is the Re-examination of Developers

If UTXO can carry long-term contracts without introducing global states, BTCFi, RWA, payments, NFTs, and on-chain data gain an additional implementation method: assets, states, and spending conditions remain within the same type of transaction structure, allowing unrelated work to be processed in parallel. What TBC is striving for is the feasibility of this technical branch.

However, innovative architecture does not equate to adoption already occurring. TBC still faces issues such as tool maturity, independent performance testing, developer numbers, node distribution, and real application loads. The most important next step is not to add another grand adjective but to enable external teams to reproduce transactions on the testnet, deploy contracts, measure performance, and review code.

Geeks do not have to believe the statement "UTXO can be programmed." Open TBCNODE, install tbc-contract, verify the versions corresponding to the two audits, and let the code answer for itself.

Source Materials

• TBCNODE Code Repository
• TBC-Contract SDK
• TBC JavaScript Library
• TuringBitChain White Paper
• CertiK TuringBitChain Audit
• SlowMist TBCNODE Audit Report