WASM toolchain

x07 wasm covers:

• build+run loops for solve-pure X07 programs as WASM modules
• WASI 0.2 components (HTTP + CLI runnable targets)
• hardening surfaces (toolchain pin validation, runtime budgets, and core-wasm HTTP reducers)

This surface is implemented by the x07-wasm tool (repo: x07-wasm-backend).

Status (2026-06): core WASM modules and WASI components are the active surfaces. The web-ui, app-bundle, and device lanes were removed in the 2026-06 refocus along with the archived x07-web-ui / x07-device-host repos.

Delegation model

The core toolchain delegates WASM commands:

• x07 wasm ... delegates to x07-wasm ... on PATH.
• If x07-wasm is not installed/discoverable, delegated commands exit with code 2.

Install

Primary path:

x07up component add wasm
x07 wasm doctor --json

Fallbacks:

cargo install --locked x07-wasm --version <VERSION>

Use cargo install --locked --git https://github.com/x07lang/x07-wasm-backend.git x07-wasm only when you need unreleased development state from the repo.

The canonical runnable projects and CI scripts live in x07-wasm-backend/examples/.

Component builds also require additional tools on PATH (checked by x07 wasm doctor):

• wasm-tools
• wit-bindgen
• wac
• wasmtime

Profiles (contracts-as-data)

x07-wasm consumes a pinned profile registry by default:

• arch/wasm/index.x07wasm.json
• arch/wasm/profiles/*.json

Validate these files in CI:

x07 wasm profile validate --json

If you need to bypass the registry (e.g. experimentation), use --profile-file.

Build

x07 wasm build delegates to x07-wasm build and selects a backend via the wasm profile’s codegen_backend field (or --codegen-backend override):

• native_x07_wasm_v1 (default): calls x07 build --emit-wasm ... and skips clang / wasm-ld
• c_toolchain_v1 (legacy): x07 build --freestanding --emit-c-header ... → clang → wasm-ld

In both cases it emits a wasm artifact manifest and a machine report.

Example:

x07 wasm build \
  --project ./x07.json \
  --profile wasm_release \
  --out dist/app.wasm \
  --artifact-out dist/app.wasm.manifest.json \
  --json

Run

x07 wasm run instantiates the module under Wasmtime and calls x07_solve_v2 using the WASM Basic C ABI sret convention.

On failures, it writes a deterministic incident bundle under .x07-wasm/incidents/… containing:

• input.bin
• run.report.json
• wasm.manifest.json (if discoverable next to the wasm path)

Machine discovery

Agents should use:

• x07 wasm --cli-specrows
• x07 wasm cli specrows check

Components (WASI 0.2)

This section introduces a component pipeline:

• WIT registry: arch/wit/index.x07wit.json (vendored, pinned)
• Component profile registry: arch/wasm/component/index.x07wasm.component.json

Validate (offline, no external validators):

x07 wasm wit validate --json
x07 wasm component profile validate --json

Native targets (adapterless, no compose):

x07 wasm component build --project examples/http_echo/x07.json --emit http-native --json
x07 wasm component targets --component target/x07-wasm/component/http.component.wasm --wit wit/deps/wasi/http/0.2.8/proxy.wit --world proxy --json
x07 wasm serve --mode canary --component target/x07-wasm/component/http.component.wasm --request-body @examples/http_echo/tests/fixtures/request_body.bin --json

x07 wasm component build --project examples/solve_pure_echo/x07.json --emit cli-native --json
x07 wasm component targets --component target/x07-wasm/component/cli.component.wasm --wit wit/deps/wasi/cli/0.2.8/command.wit --world command --json
x07 wasm component run --component target/x07-wasm/component/cli.component.wasm --stdin examples/solve_pure_echo/tests/fixtures/in_hello.bin --stdout-out dist/stdout.bin --json

Composed path (adapters + wac plug):

x07 wasm component build --project examples/http_echo/x07.json --emit solve --json
x07 wasm component build --project examples/solve_pure_echo/x07.json --emit http-adapter --json
x07 wasm component compose --adapter http --solve target/x07-wasm/component/solve.component.wasm --out dist/app.http.component.wasm --json
x07 wasm component targets --component dist/app.http.component.wasm --wit wit/deps/wasi/http/0.2.8/proxy.wit --world proxy --json

Notes:

• component build --emit all builds solve + http + cli (composed). Build adapters explicitly via http-adapter|cli-adapter.
• Native HTTP components surface failures via response headers (x-x07-diag-code, optional x-x07-diag-data-b64). Native CLI components surface failures via stderr sentinel lines (x07-diag-code: ...).

Run (legacy composed artifacts):

x07 wasm serve --mode canary --component dist/app.http.component.wasm --request-body @examples/http_echo/tests/fixtures/request_body.bin --json
x07 wasm component run --component dist/app.cli.component.wasm --stdin examples/solve_pure_echo/tests/fixtures/in_hello.bin --stdout-out dist/stdout.bin --json

Archived lanes (web-ui / device / app bundle)

The web-ui (x07 wasm web-ui ...), device bundle (x07 wasm device ...), and full-stack app-bundle (x07 wasm app ...) lanes — together with the std-web-ui package and the iOS/Android project generators — were removed in the 2026-06 refocus along with the archived x07-web-ui and x07-device-host repos.

Hardening

Toolchain pins as data (CI gate):

x07 wasm toolchain validate --profile arch/wasm/toolchain/profiles/toolchain_ci.json --json

Runtime limits can be overridden per command (all optional; defaults come from the selected wasm profile):

x07 wasm run --max-fuel 10000 --max-memory-bytes 67108864 --max-table-elements 10000 --max-wasm-stack-bytes 1048576 --json

Optional profile-level host runtime knobs:

• runtime.instance_allocator: on_demand (default) or pooling
• runtime.cache_config: path to a Wasmtime cache config file (loaded by the host)

Shipped WASM profiles include:

• wasm_release_cached (enables Wasmtime compilation cache via arch/wasm/toolchain/wasmtime_cache.toml)
• wasm_release_pooling (pooling allocator)

Core-wasm HTTP reducer contracts + loop:

x07 wasm http contracts validate --strict --json