Programmability

Sigil’s programmability is split into three surfaces: a native typed executor for primitives, a privileged WASM system-contract registry for chain policy, and per-organisation WASI zones for user code.

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Native typed executor

The native executor handles 58 transaction variants directly in Rust. Each variant has a typed argument struct, a deterministic semantic check, and an apply function that writes to AkashaKV under a typed state partition. The native path is preferred for primitives that benefit from being uniformly available, deterministic, and gas-free: transfers, validator operations, DEX swaps, NFT mints, name registration, mail delivery commitments, mandate issuance, and Vigil callbacks. The executor is split per category in node/sigil-node/src/executor_*.rs. Adding a new primitive is a change to sigil-core (types) and sigil-node (executor), tested under node/sigil-node/tests/.

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System contracts

Chain policy lives in privileged WASM system contracts. The registry is deployed at genesis and addressable by canonical name. The full set: System contracts run inside a Wasmtime executor with deterministic gas accounting. They have read access to all state partitions and write access only to their declared partitions. A system-contract upgrade requires a governance proposal under sigil.system.governance plus a 90-day timelock. The upgrade is the only mechanism to change a system contract; there is no admin key.

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Organisation zones

Zones are scoped WASI execution environments owned by an organisation DID. A zone can:

• Deploy private contracts in the zone’s namespace.
• Hold its own balance.
• Route messages to other zones through CZAC channels.
• Pin storage through the storage marketplace.
• Mint zone-local tokens and NFTs.

Each zone is gas-metered separately. Cross-zone messaging uses the CZAC (Cross-Zone Atomic Channel) protocol, which guarantees exactly-once delivery and ordered semantics. Zones do not have admin keys. Zone-policy changes are governed by the zone’s organisation DID, which may be an mhr operating under a FROST threshold. Implementation: node/sigil-zone/src/*.rs. CZAC: node/sigil-czac/src/*.rs.

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Gas accounting

Native transactions pay a flat per-class fee under a local fee market. System-contract and zone calls pay Wasmtime gas at a rate set by sigil.system.parameters.

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Determinism

All three surfaces are deterministic:

• The native executor has no floating-point arithmetic, no wall-clock reads, no network I/O.
• Wasmtime is compiled with non-deterministic features disabled (no SIMD instructions that vary across CPUs, no threads, no nan payload propagation).
• All randomness comes from the on-chain randomness beacon.

Sigil enforces determinism through differential fuzzing across builds; see node/sigil-fuzz/.

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Limits

These limits are enforced both at admission and at apply.