go-config

Module: forge.lthn.ai/core/go-config

Layered configuration management for the Core framework. Values are resolved in priority order: defaults -> file -> environment variables -> flags. Backed by Viper with YAML persistence at ~/.core/config.yaml.

Architecture

File	Purpose
`config.go`	`Config` struct, `New()`, `Get()`, `Set()`, `Commit()`, `LoadFile()`, file helpers
`env.go`	Environment variable handling
`service.go`	Core DI service integration

Key Types

Config

Config — Implements core.Config interface. Uses dual Viper instances: one for full config (file + env), one for file-only (for safe persistence without env leakage).
Option — Functional options: WithMedium(), WithPath(), WithEnvPrefix()

Operations

Method	Description
`Get(key, out)`	Retrieve value by dot-notation key, unmarshal into `out` pointer. Empty key unmarshals entire config.
`Set(key, v)`	Store value in memory (call `Commit()` to persist)
`Commit()`	Persist changes to YAML file on disk
`LoadFile(m, path)`	Merge a config file (YAML or .env) into current config
`All()`	`iter.Seq2[string, any]` iterator over all settings
`Path()`	Returns config file path

Package Functions

Function	Description
`Load(m, path)`	Read YAML file, return `map[string]any` (deprecated)
`Save(m, path, data)`	Write `map[string]any` to YAML file

Usage

import "forge.lthn.ai/core/go-config"

// Create config (defaults to ~/.core/config.yaml)
cfg, _ := config.New()

// With options
cfg, _ := config.New(
    config.WithPath("/custom/config.yaml"),
    config.WithEnvPrefix("MYAPP"),
)

// Dot-notation access
cfg.Set("dev.editor", "vim")

var editor string
cfg.Get("dev.editor", &editor) // editor = "vim"

// Persist to disk
cfg.Commit()

// Environment variables override: CORE_CONFIG_DEV_EDITOR=code
// (prefix CORE_CONFIG, dots replaced with underscores)

Dependencies

forge.lthn.ai/core/go-io — File I/O abstraction
forge.lthn.ai/core/go-log — Error handling
forge.lthn.ai/core/go/pkg/core — Implements core.Config interface
github.com/spf13/viper — Configuration engine
gopkg.in/yaml.v3 — YAML marshalling