llmkit-go

README

llmkit-go

Provider-neutral Go primitives for typed LLM programming.

llmkit-go is a small toolkit for code that wants structured LLM output without taking a dependency on a specific model provider SDK. It focuses on four stable boundaries:

• settle: bounded stabilization with complete attempt evidence.
• llmschema: Go type to JSON Schema projection and schema-enforced decode.
• llmadapter: one provider-neutral typed call with execution evidence.
• llmstep: typed validation-feedback retries with stage-specific history.

Concrete provider callers live in separate modules. This repository does not own provider transport, provider credentials, prompt libraries, tracing backends, or business validation rules.

Status

The v0.3 API is available as the v0.3.0-rc.1 release candidate. This project is still pre-v1, and the public API is intentionally small; see API compatibility before depending on it from a library with a strict compatibility policy.

Packages

Package	Purpose	Provider dependencies
github.com/ronhuafeng/llmkit-go/settle	Run and validate bounded candidates while preserving stage-specific attempt history.	Standard library only.
github.com/ronhuafeng/llmkit-go/llmschema	Project Go output types to provider-neutral JSON Schema, validate responses, and decode typed values.	Uses JSON Schema projection and validation libraries.
github.com/ronhuafeng/llmkit-go/llmadapter	Build one typed request, preserve provider-neutral execution evidence, and decode the final value.	Depends on llmschema; no concrete provider SDK.
github.com/ronhuafeng/llmkit-go/llmstep	Run typed validation-feedback retries while preserving every request/call/decode/validation stage.	Depends on llmadapter and settle; no concrete provider SDK.

The internal/ tree contains repository tests and is not public API.

Installation

Requires Go 1.23 or newer.

go get github.com/ronhuafeng/llmkit-go@v0.3.0-rc.1

Quick Start

settle

Use settle.Run when an operation may need a few bounded attempts before the output is acceptable.

package main

import (
	"context"
	"fmt"
	"strings"

	"github.com/ronhuafeng/llmkit-go/settle"
)

type op struct {
	attempt int
}

func (o *op) Run(ctx context.Context, input string) (string, error) {
	o.attempt++
	if o.attempt == 1 {
		return "draft", nil
	}
	return input + " final", nil
}

func (o *op) Validate(ctx context.Context, input, result string) (bool, error) {
	return strings.Contains(result, input), nil
}

func main() {
	got, err := settle.Run(context.Background(), &op{}, "ship", 3)
	if err != nil {
		panic(err)
	}
	fmt.Println(got)
}

llmschema

Use llmschema when you need the JSON Schema for an expected output type or need to decode the provider's final structured JSON.

package main

import (
	"fmt"

	"github.com/ronhuafeng/llmkit-go/llmschema"
)

type Verdict struct {
	Status string `json:"status" jsonschema:"short final status"`
	Score  int    `json:"score,omitempty"`
}

func main() {
	schema, err := llmschema.SchemaJSONFor[Verdict]()
	if err != nil {
		panic(err)
	}
	fmt.Println(string(schema))

	value, err := llmschema.Decode[Verdict]([]byte(`{"status":"pass","score":2}`))
	if err != nil {
		panic(err)
	}
	fmt.Println(value.Status)
}

llmadapter

Use llmadapter to keep provider-specific transport behind a narrow interface. Your provider caller receives a prompt and schema, then returns the final JSON text to decode.

package main

import (
	"context"
	"fmt"

	"github.com/ronhuafeng/llmkit-go/llmadapter"
)

type staticCaller struct{}

func (staticCaller) Call(ctx context.Context, request llmadapter.Request) (llmadapter.Response, error) {
	// A real caller would send request.Prompt and request.OutputSchema to a provider.
	return llmadapter.Response{FinalResponse: `{"answer":"yes"}`}, nil
}

type Answer struct {
	Answer string `json:"answer"`
}

func main() {
	result, err := llmadapter.ValueDetailed[Answer](context.Background(), staticCaller{}, "Return yes.")
	if err != nil {
		panic(err)
	}
	fmt.Println(result.Value.Answer)
}

Use Value when only the typed value is needed. ValueDetailed is the core path and also returns the complete provider-neutral response on success or failure. Provider-specific exact facts remain available through typed ProviderDetails implementations supplied by adapters.

Ownership and snapshots

Detailed APIs publish owned, isolated snapshots of toolkit-owned state. This is an aliasing guarantee for state whose representation the toolkit owns, not a promise that every returned Go value is deeply immutable.

• llmadapter.Request.OutputSchema is cloned before caller invocation. Callers may use or mutate their copy during Call, but must not retain and later mutate toolkit-owned request state in a way that affects another call.
• llmadapter.ValueDetailed preserves available response evidence on call and decode errors and clones Execution.Usage before publication.
• Provider adapters own ProviderDetails cloning. When details are provided, they must be an isolated, non-nil typed value whose provider identity matches neutral execution evidence; they must not alias mutable transport or SDK state.
• ValueResult.Value, settle.Result.Output, attempt candidates, and llmstep.Result.Output follow ordinary Go value semantics. Maps, slices, pointers, and custom mutable fields are not generically deep-copied.
• settle attempt slices and llmstep attempt, validation, feedback, code, and location slices are copied before publication.

An adapter should copy provider-owned reference fields while constructing its details value. For example, details{Headers: maps.Clone(response.Headers)} is safe; details{Headers: response.Headers} is unsafe if the transport may later mutate that map. Applications requiring deeply immutable generic outputs should use immutable domain types or explicitly clone their values.

Detailed field ownership is summarized below. Scalar strings, booleans, integers, stages, and errors are copied by normal Go assignment.

Published field	Ownership and aliasing contract
Request.Prompt	Go string value.
Request.OutputSchema	Toolkit-owned bytes cloned before Caller.Call.
Response.FinalResponse	Go string value, preserved when available on call/decode failure.
Response.Execution	Provider-neutral value; its Usage pointer is cloned by ValueDetailed.
Response.ProviderDetails	Adapter-owned isolated typed value; the adapter must remove mutable runtime aliases.
ValueResult.Value	Generic value with ordinary Go semantics; reference fields may alias.
ValueResult.Response	Available response evidence preserved on call/decode errors with the ownership rules above.
settle.Result.Output and Attempt.Output	Generic values with ordinary Go semantics; the latest result and recorded candidate may share reference fields.
settle.Result.Attempts	Toolkit-owned slice snapshot; scalar attempt fields and errors use normal Go assignment.
llmstep.Result.Output and Attempt.Call.Value	Generic values with ordinary Go semantics; reference fields may alias.
llmstep.Result.Attempts	Toolkit-owned slice snapshot.
llmstep.Attempt.Feedback and Validation.Feedback	Toolkit-owned snapshots including nested Codes and Locations slices.
llmstep.Attempt.Call.Response	Response evidence following the llmadapter.Response rules above.

llmstep

Use llmstep when one typed structured-output call needs deterministic validation and bounded retries with sanitized validation feedback.

result, err := llmstep.Run(ctx, llmstep.Step[ReviewInput, ReviewResult]{
	Caller:   caller,
	Render:   renderReviewPrompt,
	Validate: validateReviewResult,
	MaxIter:  3,
}, input)

Use settle.Run directly when retry state already lives in your operation and you do not need validation feedback passed back into prompt rendering.

Use settle.RunDetailed and llmstep.RunDetailed when callers need candidates, attempt errors, validation feedback, provider response evidence, or the latest partial output after a failure or exhausted retry bound.

API Compatibility

Public API is limited to exported identifiers in these packages:

• settle
• llmschema
• llmadapter
• llmstep

Everything under internal/ is private. README examples are illustrative and may change, but they are compiled in tests where practical. Exported package behavior and the canonical handwritten API allowlist are compatibility surface.

Before v1.0.0, this project follows SemVer with a conservative pre-v1 policy: patch releases should be bug fixes only, minor releases may add API, and any known breaking API change must be called out in CHANGELOG.md and the release notes. After v1.0.0, breaking public API changes require a new major version.

Version 0.3 removes the helpers deprecated in v0.2. See Migrating to v0.3 for the complete symbol mapping.

Versioning

Releases are tagged as standard Go module tags. The current release candidate is:

VERSION=v0.3.0-rc.1
git tag -a "$VERSION" -m "llmkit-go $VERSION"
git push origin "$VERSION"

See docs/release.md for the release checklist.

Testing

Run the same checks used by CI:

gofmt -w $(find . -name '*.go' -not -path './vendor/*')
test -z "$(gofmt -l $(find . -name '*.go' -not -path './vendor/*'))"
go vet ./...
go test ./...

If this repository is inside a larger local go.work, use GOWORK=off to verify it as a standalone module:

GOWORK=off go test ./...

Security

Do not report vulnerabilities by opening a public issue with exploit details. Use GitHub private vulnerability reporting:

https://github.com/ronhuafeng/llmkit-go/security/advisories/new

See SECURITY.md for supported versions and disclosure handling.

License and Dependency Provenance

llmkit-go is released under the MIT License. See LICENSE.

Dependency provenance is tracked in THIRD_PARTY_NOTICES.md and should be reviewed before each release.

Contributing

Issues and pull requests are welcome. Please read CONTRIBUTING.md and CODE_OF_CONDUCT.md first.

Related Modules

This repository is intentionally provider-neutral. Provider-specific callers, SDK wrappers, application policy, and business validation should live in separate modules that depend on this one.