# Path D — `kind = 'Wasm`

Phase B per ADR-030 — **declarable today, executive backend deferred**.
The op body is a WASM component implementing a WIT-typed interface; the
daemon (when built with `--features wasm`) hosts it via `wasmtime`
inside an explicit capability sandbox.

## Files

| File | Purpose |
| --- | --- |
| [`render_provisioning_report.ncl`](render_provisioning_report.ncl) | Catalog declaration with `kind = 'Wasm` and a fully-populated `body` |
| [`render_provisioning_report.wit`](render_provisioning_report.wit) | WIT interface — the host/guest contract |

## What the `body` declares

| Field | Value | Meaning |
| --- | --- | --- |
| `module_path` | `.ontoref/catalog/wasm/render_provisioning_report.wasm` | Built WASM artefact, project-relative |
| `export_name` | `ontoref:catalog/op#render` | Exported function the host calls |
| `capabilities` | `["fs:read:.ontology/provisioning/", "fs:read:.ontoref/catalog/", "net:none"]` | Explicit grant set — anything else traps |

## Today's runtime behaviour

Dispatching against a stock daemon returns:

```
HTTP/1.1 501 Not Implemented
{
  "error": "missing_executive_backend",
  "kind":  "Wasm",
  "op_id": "render_provisioning_report",
  "hint":  "rebuild ontoref-daemon --features wasm (awaiting ADR-030 T3/T4/T5 trigger)"
}
```

This is intentional per ADR-034 constraint
`non-rust-kinds-declarable-not-executable-without-flag`. The op
declaration is a first-class catalog entry that consumers can read
cross-project via ADR-028 content-addressing right now.

## Building the WASM artefact (when the executive backend lands)

```sh
# 1. Author the implementation against the WIT interface — any source
#    language that supports the component model: Rust, AssemblyScript,
#    Go (with tinygo), Zig, Python (via Pyodide), …

# 2. For a Rust implementation:
cargo build -p render-provisioning-report --target wasm32-unknown-unknown --release

# 3. Convert the core wasm to a component:
wasm-tools component new \
  target/wasm32-unknown-unknown/release/render_provisioning_report.wasm \
  -o .ontoref/catalog/wasm/render_provisioning_report.wasm
```

## Why WASM is Phase B (deferred)

Per ADR-030 the WASM backend awaits one of:

- **T3** — cross-instance ops dispatch becomes the bottleneck (HTTP IPC
  chain in Path B Sidecar exceeds acceptable latency)
- **T4** — toolchain divergence — an instance wants ops in
  Go / Python / AssemblyScript and dynlib is too brittle
- **T5** — untrusted ops authors — the deployment must sandbox ops from
  outside the instance's control

None of these have fired empirically. Path B (Sidecar) covers the
shared-domain near-term case at ~80 LOC of daemon proxy; WASM lands
when concrete pressure justifies the wasmtime dependency.

## Key properties

- **`evaluate_ondaod` is mandatory** — the host invokes ondaod
  discipline BEFORE entering the sandbox. The WASM module cannot reach
  the ondaod context.
- **Witness honesty** — `payload_kind = "wasm_call_envelope"`. The
  daemon's Ed25519 signature attests the inputs it passed and the
  outputs it received; it does NOT claim to attest the WASM-internal
  computation (the sandbox is honest about being a black box).
- **Capability sandbox** — every fs/net interaction must be in the
  `capabilities` list. Anything else returns a wasmtime host trap.
  Designed for the T5 untrusted-author case.
- **wasmtime is NOT in the default daemon build** — ADR-034 constraint
  `wasmtime-not-in-default-daemon-build`. Honours `protocol-not-runtime`
  axiom (invariant=true).

## When NOT to use

- Your op is part of the ontoref piloto → Path A `'Rust`.
- Your project is a shared-domain instance and the bottleneck is
  process management overhead, not the IPC boundary → Path B
  `'Sidecar` is the right Phase A answer.
- The op is a trivial NCL data-transform → Path C `'NclTransform`
  (lower complexity than WASM, no wasmtime needed).

## References

- [ADR-034 — Catalog extensibility beyond Rust](../../../.ontoref/adrs/adr-034-catalog-extensibility-beyond-rust.ncl)
- [ADR-030 mechanism #3 — WasmComponents](../../../.ontoref/adrs/adr-030-catalog-discovery-cross-project.ncl)
- [`schema-future.ncl::WasmBody`](../schema-future.ncl)
- [WIT component model spec](https://component-model.bytecodealliance.org/design/wit.html)