lcgo (github.com/cto-up/lcgo-lib)

A Go library for LLM prompt management and text generation, built on langchaingo. It powers the prompt features of the CtoUp platform and is consumed by an application that wires its handlers into a Gin server.

Features

• Prompt store + REST API — multi-tenant CRUD over prompts (core_prompts), plus endpoints to format a prompt (template substitution) and execute it against an LLM, with optional Server-Sent-Events streaming.
• gochains — a builder-style wrapper around langchaingo LLMChain supporting plain-text and structured (JSON) output, with response-schema validation.
• Multi-provider LLM factory — OpenAI, GoogleAI (Gemini), Mistral, Anthropic, and Ollama, selected at runtime; API keys are read from the environment.
• pgvector vector store — a custom langchaingo VectorStore for PostgreSQL + pgvector with similarity search filtered by tenant, ACL roles, and tags.

Layout

Path	Purpose
pkg/core/api/	PromptHandler (REST handlers) + OpenAPI specs in openapi/
pkg/core/service/	Generation and prompt-execution services
pkg/core/service/gochains/	Chain abstraction (BaseChain, ChainBuilder) and output parsers
pkg/core/db/	SQLC-generated repository, Goose migrations, queries
pkg/shared/llmmodels/	LLM provider factory
pkg/shared/pgvector/	pgvector vector store
api/openapi/core/	Generated Go server/types (do not edit)
cmd/prompt/	Example CLI that runs the sample chains
internal/example/	Sample chains used by the CLI

Dependencies

This module uses ctoup.com/coreapp (auth, multi-tenancy, request middleware, progress events, DB helpers) via a replace directive pointing at the sibling repo ../core-be-lib. The frontend TypeScript client is generated into ../lcgo-fe-lib.

Getting started

# Configure environment (DB connection, LLM API keys, LOG_FOLDER, BACKEND_PORT)
cp .env .env.local        # then edit .env.local

# Regenerate code after editing specs or SQL
make openapi
make sqlc

# Build the example CLI
make build-prompt

# Run tests (unit tests run offline; integration tests need LLM API keys / Postgres)
go test ./...

See CLAUDE.md for architecture and development workflows, and CONVENTIONS.md for conventions.

Release Management

Automated versioning is handled via the Makefile:

make release VERSION=v0.0.1 NOTES="Description of changes"

License

Distributed under the MIT License.