rWasm

rWasm is Fluent’s Wasm-derived execution substrate inside the blended VM architecture.

Its role is to make heterogeneous execution more deterministic and proving-friendly while preserving a practical Wasm developer path.

Architectural role in Fluent

In Fluent’s blended model, rWasm is the execution representation that helps unify runtime behavior across different integration paths.

At system level, this supports:

• one shared state-transition model,
• host-governed interruption/syscall boundaries,
• deterministic commit semantics.

Why rWasm instead of plain Wasm modules everywhere

Plain Wasm is developer-friendly but includes representation/runtime assumptions that are not always ideal for protocol-grade deterministic/proving workflows.

rWasm addresses this by using:

• a constrained translation/execution model,
• explicit module/runtime boundaries,
• a dedicated opcode/runtime surface designed for predictable behavior.

Current implementation shape (from fluentlabs-xyz/rwasm)

1) Translation pipeline

Wasm input is validated and translated into a compact rWasm module consumed by the runtime.

2) Module encoding contract

rWasm modules use explicit header/versioning and ordered sections. This is treated as compatibility-sensitive wire format.

3) Runtime VM + strategy layer

The runtime includes a native VM executor and a strategy abstraction for optional compatibility/comparison execution backends.

4) Fuel-first metering

Fuel limits and consumption are explicit runtime controls, including deterministic out-of-fuel behavior.

5) Optional tracing

Tracing can capture execution/memory/table events for debugging and analysis pipelines.

Determinism and security boundary

rWasm determinism depends on both:

• VM semantics, and
• host import/syscall behavior.

So runtime correctness requires deterministic host integration, not only deterministic opcode dispatch.

Status notes for readers

• rWasm docs evolve with implementation; treat exact opcode and module-format details as version-sensitive.
• For current production behavior, consult fluentlabs-xyz/rwasm/docs/* plus active Fluentbase/reth release docs.