[nilslice]

Ports the combined Extism Erlang SDK work from nilslice/agent-plan-executor#13 into this repository.

This is a native Extism host SDK for Erlang/OTP. Plugins run on erlang_wasm. The library implements the Extism kernel, host env, manifests, host functions, and WASI on that engine.

Requires OTP 29+.

API sketch

{ok, P} = extism:open("priv/plugins/count_vowels.wasm"),
{ok, Out} = extism:call(P, count_vowels, <<"Hello, World!">>),
ok = extism:close(P).

The default handle lives in the calling process (no gen_server hop). start_link/2 and child_spec/3 wrap the same API in an OTP worker when you want a name or supervisor.

What's included

• Plugin load/call API (open/new/call/close) from path, bytes, WAT, bundled name, or manifest
• Host functions (PDK-shaped binaries or raw i64 offsets)
• Manifest config, allowed hosts, WASI filesystem, HTTP
• Bundled guest plugins from official Extism PDK/SDK repos (priv/plugins/SOURCES.md)
• Common Test suite covering kernel WAT, Rust PDK guests, host fns, WASI/HTTP, and OTP workers
• GitHub Actions CI (.github/workflows/ci.yml) that compiles, runs rebar3 ct, and the count-vowels example on OTP 29.1.1

Develop

rebar3 compile
rebar3 ct
rebar3 shell

GitHub links in rebar.config and extism.app.src now point at this repo instead of the plan-executor tree.

Verification

Compiled and tested locally on OTP 29.1.1 with rebar3 3.27.0:

• rebar3 compile — success
• rebar3 ct — 20/20 Common Test cases passed (kernel WAT, Rust PDK guests, host functions, WASI/HTTP, OTP worker API)
• escript examples/count_vowels.escript "Hello, World!" — {"count":3,"total":3,"vowels":"aeiouAEIOU"}
• Runtime versions: SDK 0.1.0, kernel v1.7.0