Building on vProgs

Developing on Kaspa’s Layer 1 requires robust, efficient tooling. The ecosystem is rapidly maturing to support a seamless developer experience for writing, testing, and deploying Verifiable Programs (vProgs).

Silverscript

Kaspa introduces Silverscript, a high-level smart contract language that compiles directly into native Kaspa Script. Designed for flexibility, it empowers developers to write complex UTXO spending conditions without managing low-level assembly.

Recent upgrades have introduced compiler optimizations and opcode hardening, improving both the security and performance of the smart contract language as it moves closer to a production-ready state.

Community-driven testing recently identified and resolved a critical bug causing mismatches between compile-time and runtime integer math. This fix prevents silent, hard-to-debug errors and significantly improves the overall reliability of vProg execution.

Recently, a major refactoring of the SilverScript codebase was completed (PR #91). This significant overhaul simplifies the architecture, paving the way for more stable and rapid future development of the language.

Currently, an ecosystem consensus is forming to steer early development efforts toward Covenants. Because Silverscript offers a familiar, Solidity-like syntax, this strategy effectively lowers the barrier to entry, accelerating the deployment of smart contracts by providing a more accessible path than building low-level ZK-based vProgs directly.

Ongoing development continues to advance Silverscript’s core capabilities. Recent pull requests (such as PRs #95 and #96) iteratively build out the scripting functionality required for Kaspa’s next-generation smart contract layer.

Silverscript’s syntax and paradigms are continually refined to reflect its secure on-chain environment. For example, array handling is shifting from the mutable x.push(a) method to an immutable x = x.append(a) function. This enforces an immutable execution model, a key principle for writing secure and predictable smart contract logic.

To support the creation of standard assets, a recent pull request (PR #111) was merged into the SilverScript repository featuring successful tests against a KCC20 token example. This marks tangible progress in building the foundational tooling required for token standards on Kaspa’s upcoming smart contract platform.

To further modernize the language, recent updates have expanded SilverScript’s syntax capabilities by adding support for the ternary operator and allowing tuples to be returned from functions. These enhancements streamline contract code and significantly improve the developer experience for building on Kaspa.

Opcode Refinement and Standardization

The underlying native Kaspa Script is being continuously enhanced to support advanced applications. Recent developments include:

• Arbitrary Data Signatures: New opcodes (such as the proposed checkdatasig / CheckSignedMsgFromStack under review in PR #926) allow covenants to verify signatures on arbitrary data directly from the stack.

• Standardized Documentation: Comprehensive, standardized documentation for opcode stack usage is being rolled out to clarify developer expectations and reduce bugs.

• Flexible Number Encoding: The requirement for minimally encoded numbers in scripts has been removed from rusty-kaspa. This protocol simplification liberalizes integer encoding rules, offering greater flexibility for vProg developers and tooling.

• Advanced Authentication: The integration of new signature-checking opcodes (checkDataSig / checkSigFromStack) into both rusty-kaspa and the SilverScript compiler provides a fundamental building block for enabling complex authentication logic.

• Cross-Chain Opcode Research: Developers are actively analyzing use cases for BCH’s OP_CHECKDATASIG (typically used for oracle price verification) to evaluate proven patterns for on-chain data validation. Concurrently, discussions around OpCheckSigFromStack highlight its potential to enable concurrent payments and state validation without requiring consensus changes, effectively decoupling actions from specific UTXOs.

• Resource Metering & Execution Cost Model: The txscript engine has been refactored to introduce a versioned RuntimeResourceMeter, unifying legacy Sigops and the new ScriptUnits for computational cost. The vProgs execution cost model (or ‘gas’ model) calculates script units based specifically on signature units, pushed bytes, and hashed bytes (such as Blake3 and Blake2b). To enforce robust script pricing for vProgs, transactions that mix old and new input mass accounting are now rejected, mandating the use of the new compute_budget field.

• Script Pricing Benchmarks: Recent benchmarks for Kaspa’s script engine revealed that hashing opcodes required price adjustments for the new compute-budget model. A recent proposal (PR #971) updates these costs based on performance, ensuring gas fees accurately reflect computational work.

• Finalized Script Limits & Benchmarks: A major pull request has recently been merged into Rusty Kaspa that finalizes transaction script limits, tunes execution benchmarks, and resolves legacy codebase TODOs. This represents a significant step in stabilizing the vProgs (KIP-21) implementation for both security and performance.

• Script Engine Activation & Fork-Awareness: A crucial PR (#987) has been merged, making the codebase “fork-aware” and adding activation logic for new script engine constants. Developers can now build scripts for either pre- or post-Toccata rules using ScriptBuilder::with_flags, ensuring a smooth transition to advanced scripting features and the eventual vProgs hard fork.

• Script Pricing Model: Kaspa developers are planning an upcoming KIP to formalize script execution pricing. Defining this robust cost model is essential for the long-term security and sustainability of the smart contract system.

• Script Engine Hardening: To ensure robustness ahead of activation, developers are actively analyzing script execution edge cases, particularly the interactions and limits between maximum element sizes and maximum script sizes.

• KIP-17 and opBlake3: KIP-17 is being updated to formally document new opcodes like opBlake3, which are already active on the Toccata testnet. This process of standardizing powerful cryptographic primitives is a key step in preparing the developer toolset for the vProgs launch.

• KIP-21 Script Units Alignment: The vProgs proposal (KIP-21) is being actively updated to reflect the latest protocol design, specifically adjusting consensus parameters to align with the recently introduced ‘script units’ KIP to ensure the formal specification matches the final implementation.

• API Clarity & DX: To improve long-term clarity in the vProgs model, developers are discussing renaming the tx.mass field to tx.storage_mass across the API and tooling. A two-phase deprecation plan has been proposed to minimize disruption while prioritizing code maintainability and a better developer experience.

• Post-Quantum Signature R&D: Kaspa developers are researching post-quantum signature schemes like HAWK, which offers performance benefits without requiring float math. This exploration is vital for ensuring the long-term security of vProgs and the broader Kaspa ecosystem.

Enhanced Debugger Capabilities & WebAssembly

Building decentralized applications on a parallelized BlockDAG requires deep visibility into execution paths. The Kaspa developer tooling suite is expanding to include enhanced vProg debugger capabilities, allowing developers to step through complex multi-contract flows, inspect stack states, and simulate transactions locally before deploying to the TN12 testnet. Additionally, WebAssembly support continues to bridge the gap for browser-based toolchains and client-side proof generation.

To further streamline integration, recent architecture refinements (such as PR #935 in Rusty-Kaspa) separate core logic from WASM-specific types. This separation paves the way for easier usage across native Rust and Python SDKs. Meanwhile, rigorous R&D on the testnet continues to fortify the smart contract layer; active testing has identified and addressed vital edge cases, including potential integer overflow and clamping issues with large numbers.

SilverScript now officially supports source-level debugging and complex state-transition test scenarios. This represents a major leap in developer experience, drastically simplifying the process of building and testing sophisticated smart contracts.

Update: Debugging support for covenants in SilverScript has been successfully rebuilt. The new implementation introduces a much leaner architecture by separating debugging logic from the core compiler. Developers can now debug covenants by defining transaction context directly in a test file and injecting it at the session layer, streamlining the process while preventing compiler bloat.

Recent updates to the WASM SDK (such as PR #951) have refined how mempool data is requested, representing tangible progress in improving the developer toolchain for Kaspa smart contracts.

To further enhance portability, several core Rusty-Kaspa crates—including kaspa_hashes—have recently been updated to be no-std compatible. This crucial upgrade enables Kaspa’s core cryptographic logic to run seamlessly in constrained environments like WebAssembly (WASM) and embedded systems, vastly expanding the possibilities for lightweight client-side tooling.

The Silverscript debugger (sdb) is undergoing rapid, iterative development to support the complexities of vProgs. Developers are pragmatically shipping incremental upgrades (such as PR #104) while actively addressing known edge cases, including current limitations where the debugger fails to access individual fields of a struct within an array.

To further streamline smart contract creation, development is set to resume on the SilverScript VS Code debugger extension. This renewed focus on improving the developer experience (DevEx) is essential for providing builders with the integrated IDE tools they need to confidently construct and test verifiable programs.

As a positive side-effect of dependency cleanup for the vProgs codebase—specifically the removal of the intertrait crate—Rusty-Kaspa has successfully gained support for the Android target. This expanded platform support paves the way for advanced mobile ecosystem development and native mobile client integrations.

Expanding the multi-language developer ecosystem, the Kaspa Python SDK now includes full wallet support. By leveraging the same native Rusty-Kaspa components as the WASM SDK, this update brings critical feature parity and significantly improves the toolkit for developers building cross-platform applications on Kaspa.

While the Toccata branch is now fork-aware, it is a known gap that the WASM APIs for web-based apps do not yet fully support the new scripting flags. This presents an opportunity for ecosystem developers to help align the web tooling with the upcoming protocol rules.

The Three-Layer Programmability Model

To help developers navigate Kaspa’s ecosystem, the community is framing programmability as a three-layer system:

• Covenants: Simple, L1-native local-state contracts (via Silverscript) for isolated actions and peer-to-peer flows.
• ZK-Inline: For verifying lightweight off-chain computations directly within a single transaction.
• ZK-Based (vProgs): Full off-chain execution with shared state for complex applications like rollups and heavy DeFi protocols.

This mental model clarifies the developer’s choice between on-chain versus off-chain logic based on specific application requirements.

Developer Experience (DevX)

The Kaspa R&D community is placing a heavy emphasis on Developer Experience (DevX) for the upcoming programmability features. Dedicated contributors are actively focusing on post-covenants DevX, ensuring that the powerful tools being built—from Silverscript compilers to ZK proving pipelines—are accessible, well-documented, and ready for builders.

To further assist builders ahead of the vProgs (KIP-21) release, new practical “how-to” documentation has been released, signaling a strong push to streamline developer onboarding and improve the overall development experience.

To simplify the creation of vProgs applications, developer discussions highlight that future SDKs will abstract away transaction version complexity from end-users. This will enable developers to work directly with high-level covenant bindings rather than manually managing low-level transaction structures.

The broader community is also actively contributing to the tooling ecosystem. Recently, developers released the igra-sc-sdk, an early-stage SDK tailored for modeling financial assets using Silverscript. This marks one of the first public community efforts to construct dedicated DeFi tooling for Kaspa’s emerging smart contract layer.

Core Test Suite Hardening

Maintaining a robust testing environment is critical for developer velocity and the stability of future protocol upgrades. Recent infrastructure work (such as PR #944 in Rusty-Kaspa) focuses on fixing non-deterministic tests and race conditions, ensuring that the core codebase remains reliable as complex vProgs capabilities are integrated.

Continuous iterative refinement of the core Rust implementation is ongoing, with recent codebase merges (such as PR #945 in Rusty Kaspa) reflecting a steady commitment to stabilizing the foundation before deploying complex programmability features.

ZK SDK Integration

To dramatically lower the barrier to entry for building private and zero-knowledge dApps, developers have proposed a new ZK SDK (PR #953). This SDK simplifies the process of converting standard ZK proofs, such as Groth16, directly into native Kaspa scripts, streamlining the deployment of verifiable programs and private applications.

Active collaboration on this ZK SDK pull request marks a major technical milestone. Establishing a robust ZK SDK is considered a foundational component for enabling advanced privacy and computational features natively within the vProgs (KIP-21) framework.

Furthermore, the Arkworks cryptography library—a key dependency for zero-knowledge proofs—has been updated in the Toccata development branch. This critical maintenance ensures robust support for future ZK-based applications enabled by vProgs.

Building on this, a significant architectural milestone was recently reached by making the Groth16 verifier generic over the arkworks library. This enhances the flexibility of the ZK-proof system, making it more modular and forward-compatible with future cryptographic schemes.

Testing on these environments is actively pushing the engine’s computational boundaries. For instance, developers implementing Groth16 ZK-proof verification on Kaspa’s devnet have successfully stress-tested the new script unit limits. This real-world battle-testing ensures the execution cost model is properly calibrated for advanced cryptographic primitives before mainnet deployment.

To further assist builders, new JavaScript examples are now available demonstrating how to construct Groth16 and other ZK-proof transactions on Kaspa using the new SDK builder. This provides a concrete developer pathway for implementing advanced privacy and scaling solutions.

As the Toccata branch evolves, new protocol constraints—such as a recently introduced stack element limit—are directly impacting the wider ecosystem. Developers updating the ZK-SDK are actively navigating these limits, highlighting the real-time integration challenges and necessary adaptations occurring to fully support vProgs.

Ecosystem Performance Tooling

As the Kaspa network prepares for the integration of complex vProgs and smart contract features, maintaining peak performance is critical. The developer ecosystem relies on continuously updated performance monitoring tools, such as the recently released workflow-perf-monitor-rs v0.0.3, to ensure the node software and application layers remain fast and highly efficient under load.

To avoid delays before the upcoming Toccata hard fork, developers have taken pragmatic steps such as internally forking a key performance monitoring dependency (PR #965). This unblocks the use of updated tools and highlights the team’s focus on meeting the hard fork deadline without sacrificing essential network monitoring capabilities.

To support the integrity of the state machine, a new SMT prune scanner (PR #990) has been introduced for inspecting the consensus database. This developer tool is critical for verifying and debugging the Sparse Merkle Tree, the core data structure underpinning vProgs.

Standalone Indexing Infrastructure

To address key adoption barriers and streamline integration for developers, new standalone indexing tools like go-kaspabook are being created. Utilizing RocksDB, this indexer aims to provide a simple REST API for Kaspa data, making it easier for services and dApps to interface with the network without the overhead of running and maintaining a full node.

An early version of go-kaspabook has recently been released by a community developer. By utilizing RocksDB and protobuf for efficient data storage, this release marks a tangible step forward in providing robust, community-driven tooling for the ecosystem.

When building or integrating with these indexers, developers must account for unique blockDAG edge cases. Notably, Kaspa’s DAA score is not strictly monotonic, which can create rare edge cases for state changes and ordering. Additionally, during UTXO state synchronization, clients must gracefully handle removed UTXOs that might not exist in the initial synced set. Finally, because achieving a perfectly clean state history from the network’s earliest days is likely unsolvable due to a lack of early archival nodes, indexing services must be built to be resilient to potential gaps in very early historical data. To manage the high request volumes generated by these tools, developers are currently prioritizing the scaling of existing infrastructure (such as adding servers) over immediate architectural overhauls.

Wallet Tooling and Ecosystem Compatibility

To ease operator migration and support the broader Kaspa ecosystem, a new wallet port aiming for strict compatibility with the original Go-based wallet is currently under review. This initiative has sparked valuable developer discussions regarding optimal wallet architecture and storage formats. By proactively addressing these design patterns, the community aims to prevent future tooling fragmentation and ensure robust, standardized interfaces for dApp builders and node operators.

Furthermore, developers are designing an advanced asynchronous multisig setup within the wallet framework to support user-friendly vProgs applications. This design utilizes a two-step flow to create and finalize multi-party accounts, effectively separating signer identity from the final address to enhance security and usability.