SDK Development

The SDKs in sdks/ are not part of the main build flow (cargo make build does not build them). Each SDK has its own build system and conventions.

Rust SDK (sdks/rust/)

Crates

• golem-rust — Runtime API wrappers (transactions, durability, agentic framework, value conversions). Also re-exports the #[derive(IntoSchema)] / #[derive(FromSchema)] derives, which are defined by the root-workspace golem-schema-derive crate, not by golem-rust-macro.
• golem-rust-macro — Procedural macros: #[agent_definition], #[agent_implementation], #[tool_definition], #[golem_operation], and the MultimodalSchema, ConfigSchema, AllowedLanguages, AllowedMimeTypes, and ToolError derives.

Building

cd sdks/rust
cargo build -p golem-rust
cargo build -p golem-rust-macro

Testing

Tests use test-r. Library entry points call #[cfg(test)] test_r::enable!();. Integration-test entry points call test_r::enable!(); at the top, and test_r::test must be in lexical scope for each #[test].

cargo test -p golem-rust
cargo test -p golem-rust --features export_golem_agentic  # Agent tests

Testing with the main platform

# From the repository root, after building the test components needed by <affected-test>:
cargo test -p golem-worker-executor --test integration -- <affected-test> --report-time

Use the modifying-test-components skill to build the selected test's WASM prerequisite. Run a worker-executor group or cargo make worker-executor-tests only for broad runtime, durability, value-conversion, or agent framework changes whose consumers cannot be isolated.

Testing with golem-cli

Set GOLEM_RUST_PATH to use local SDK in generated applications:

export GOLEM_RUST_PATH=/path/to/golem/sdks/rust/golem-rust
golem-cli app new my-test-app

Code style

cargo fmt -p <affected-sdk-crate> -- --check
cargo clippy -p <affected-sdk-crate> --all-targets -- -Dwarnings

TypeScript SDK (sdks/ts/)

Prerequisites

• Node.js
• pnpm (managed via packageManager field)
• wasm32-wasip2: rustup target add wasm32-wasip2 (the Preview 3 wrapper still builds through this Rust target)
• wasm-rquickjs-cli: cargo install --locked wasm-rquickjs-cli@<VERSION> (check WASM_RQUICKJS_VERSION in .github/workflows/ci.yaml)

Packages

Build order matters: golem-ts-sdk → golem-ts-bridge → golem-ts-repl.

Building

cd sdks/ts
npx pnpm install
npx pnpm run build

Testing

npx pnpm --filter <affected-package-with-a-test-script> run test
npx pnpm run test  # All packages, for cross-package changes

Check the affected package's package.json before running a package test; for example, @golemcloud/golem-ts-bridge currently has no test script.

Agent template WASM

The agent template WASM embeds the existing packages/golem-ts-sdk/dist/index.mjs. Build that bundle before rebuilding the template whenever a change can affect the emitted runtime. Triggers include:

• wasm-rquickjs-cli is updated
• WIT dependencies change
• any source or dependency in the Rollup graph rooted at packages/golem-ts-sdk/src/index.ts changes
• wrapper generation or agent-template toolchain inputs change

The filenames above are intentionally described by dependency graph rather than a fixed list: runtime modules can be added or reorganized.

npx pnpm --filter @golemcloud/golem-ts-sdk run build
npx pnpm run build-agent-template

The package build refreshes dist/index.mjs; build-agent-template then embeds it in the pre-compiled WASM. Running either command alone is not sufficient after a runtime change.

Testing with the main platform

# From repository root
cargo make build-cli-test-bins-non-ci
(cd sdks/ts && npx pnpm run build && npx pnpm run build-agent-template)
# Build the specific test components required by <affected-filter>.
cargo-test-r run --package golem-cli --test integration <affected-filter> -- --report-time --nocapture

Prefer targeted CLI integration filters that generate or exercise the affected SDK feature. They require fresh CLI binaries, SDK/template artifacts, and any selected test components. Use the full CLI suite only for broad template, bridge, REPL, or generated-application changes; after TS source changes, refresh the SDK/template first because build-sdk-ts skips when output files already exist.

Testing with golem-cli

export GOLEM_TS_PACKAGES_PATH=/path/to/golem/sdks/ts/packages
npx pnpm install && npx pnpm run build  # Build first!
golem-cli app new my-test-app

Code style

npx pnpm --filter <affected-package> run lint
npx pnpm exec prettier --check <changed-paths>

MoonBit SDK (sdks/moonbit/)

See sdks/moonbit/AGENTS.md for full details. The MoonBit SDK has its own build system (moon) and code generation tools (golem_sdk_tools).

Building

cd sdks/moonbit/golem_sdk
moon check --target wasm          # Type-check
moon build --target wasm          # Build

Testing

cd sdks/moonbit/golem_sdk
./scripts/run-sdk-tests.sh
# For a narrower package/file check that does not need the JS runner:
moon test --target wasm <affected-package-or-file>
cd sdks/moonbit/golem_sdk_tools
moon test <affected-package-or-file>

Regenerating WIT bindings

cd sdks/moonbit/golem_sdk
moon run script bindgen  # Enforces the pinned Golem wit-bindgen and required post-processing
moon info
moon fmt

Code style

moon info    # Regenerate .mbti files when public interfaces changed
moon fmt

Downstream Rebuild Requirements

SDK changes can require rebuilding test components. This is the most common source of errors.

Rust SDK change → test components

1. Build golem-rust / golem-rust-macro
2. Find Rust test components depending on the SDK: check test-components/**/Cargo.toml for golem-rust references
3. Rebuild each affected component following its AGENTS.md

TS runtime/WIT change → test components

1. Build the affected TS SDK package and its required package dependencies (npx pnpm run build in sdks/ts/ is the broad option)
2. Rebuild agent template WASM (npx pnpm run build-agent-template in sdks/ts/)
3. Find TS test components depending on the SDK
4. Rebuild each affected component following its AGENTS.md

Type-only, test-only, documentation, bridge, or REPL changes that cannot affect golem-ts-sdk/dist/index.mjs or WIT do not require an agent-template rebuild.

Test Process Ownership

SDK unit tests and worker-executor tests must not invoke external tools or Golem binaries. Put tests that execute golem, golem-cli, cargo, rustc, npm, npx, tsc, moon, or another process in the CLI integration test suite. Build SDKs, generated code, templates, and test components as prerequisites before running unit or worker-executor tests. Non-CLI integration tests use golem-test-framework for process-backed dependencies and do not spawn additional processes directly.

WIT Dependencies

The Rust, TypeScript, and MoonBit SDKs covered by this skill have WIT files synced from the root wit/ directory. Never manually edit their wit/deps/ copies.

# From repository root
cargo make wit

Checklist

1. SDK code modified
2. SDK builds successfully
3. SDK tests pass
4. Agent template rebuilt from a fresh bundle (if TS runtime bundle or WIT inputs changed)
5. Dependent test components rebuilt (if any)
6. Platform tests that exercise changed SDK/platform integration pass
7. Affected SDK code is formatted and linted with its native tools
8. Full SDK/platform suites run only for broad or unclear impact