config/

Responsibility

Centralize tmuxai runtime configuration: define schema, establish defaults, load user/custom configuration, normalize values, and expose filesystem paths used by other subsystems (config dir, kb dir).

Config is a single strongly-typed root struct (config.go) with nested structs for providers and feature areas (OpenRouter, ModelConfig, KnowledgeBase, WebSearch, WebFetch, Tmux, etc.) and mapstructure tags for Viper binding/unmarshal.
DefaultConfig() provides an explicit baseline, including sane defaults and default URLs/providers/timeouts, plus initialized map/slice fields to avoid nils where reasonable.
Load(...) performs canonicalized configuration resolution in one pass: choose config source (explicit path → TMUXAI_CONFIG env → default search paths), configure env binding (TMUXAI_*, dotted keys mapped to underscores), read config (optional), unmarshal into the struct, then post-process env variable expansion.
EnumerateConfigKeys recursively derives dotted key names from struct tags to allow env binding for all fields, including nested structs.
ResolveEnvKeyInConfig recursively traverses values via reflection, expanding $VAR references in strings; map values are deep-copied when needed for non-addressable map entries.
TryInferType is a lightweight parser for dynamic string values (bool/int) used by callers needing best-effort type inference.
Helper funcs include GetConfigDir, GetConfigFilePath, and GetKBDir for workspace path discovery and setup.

Startup/configure call: Load(configFilePath?) → DefaultConfig → Viper search/path/env setup → ReadInConfig (non-fatal if missing file) → Unmarshal into defaults → ResolveEnvKeyInConfig mutation pass.
On demand, config consumers read the returned *Config; they may call GetConfigDir/GetConfigFilePath for canonical paths or GetKBDir for KB storage (which lazily creates ~/.config/tmuxai/kb).
Env expansion is recursive across nested structs and maps, with pointers/maps guarded to avoid nil deref.

Exposes configuration values consumed by command handlers and service modules (LLM providers, web search/fetch, knowledge base, tmux actions).
Reads env vars from the process (TMUXAI_*) and YAML config (config.yaml in . or $HOME/.config/tmuxai unless overridden).
Filesystem integration via os.UserHomeDir, os.MkdirAll, and path construction in helpers to ensure config/kb directories exist when needed.
External dependency surface: github.com/spf13/viper is used for file/env/config parsing/unmarshal.