chatty-module-sdk

SDK for authoring chatty WASM plugins against chatty:plugin@0.3.0. Compile target: wasm32-wasip2.

A plugin contributes tools to a chatty agent and never runs a loop of its own: the agent’s model decides when to call a tool, and the host calls the plugin’s invoke-tool (PL-D1 option B).

This crate is intentionally outside the main workspace (see the [workspace] table at the bottom of Cargo.toml). Plugin authors depend on it as a path = "../../crates/chatty-module-sdk" from their own single-crate project rooted at the plugin directory.

What it provides

• WIT types, generated from wit/chatty-plugin.wit: PluginMetadata, Capability, ToolDefinition, ToolCallRequest, ToolResult, ToolError, Message, Role, …
• Host imports, one module per capability: llm::complete, config::get, log::info/warn/…, file::read_bytes, billing::*. A plugin lists the capabilities it uses in metadata().requested_capabilities; logging is always granted.
• Plugin, the trait a plugin implements (metadata, list_tools, invoke_tool), and export!, which wires it to the component’s exports. Both are wit-bindgen’s own generated code, so the export names always match the WIT.

hive-billing-sdk uses this crate’s billing imports, so a paid plugin can depend on both (the billing test fixture links them together).

Quick start

See the rustdoc example at the top of src/lib.rs, the reference plugins under ../../modules/ (echo, benford), and the Build a WASM plugin guide.

Build

rustup target add wasm32-wasip2
cd modules/your-plugin
cargo build --target wasm32-wasip2 --release

The output .wasm lives under target/wasm32-wasip2/release/your_plugin.wasm. Copy it next to your module.toml so the registry can discover it.

WIT version

WIT_PACKAGE is chatty:plugin@0.3.0. The build fails if wit/chatty-plugin.wit declares any other package: a WIT version bump has to update WIT_PACKAGE here and in chatty-wasm-runtime deliberately, since the host refuses every other world with “rebuild it with the current SDK”.