feat: 🎉 Vectors na Vectors, the begining

Translate 1536 <-> 768 , 3072 <-> 2048

pkg/config/config.go

@@ -0,0 +1,168 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/spf13/viper"
+)
+
+// Config is the root configuration for vecna.
+type Config struct {
+	Server  ServerConfig  `mapstructure:"server"`
+	Metrics MetricsConfig `mapstructure:"metrics"`
+	Forward ForwardConfig `mapstructure:"forward"`
+	Adapter AdapterConfig `mapstructure:"adapter"`
+}
+
+// ServerConfig controls the HTTP listener and inbound auth.
+type ServerConfig struct {
+	Port    int      `mapstructure:"port"`
+	Host    string   `mapstructure:"host"`
+	APIKeys []string `mapstructure:"api_keys"`
+}
+
+// MetricsConfig controls Prometheus metrics exposure.
+type MetricsConfig struct {
+	Enabled bool   `mapstructure:"enabled"`
+	Path    string `mapstructure:"path"`
+	APIKey  string `mapstructure:"api_key"`
+}
+
+// ForwardConfig holds all named forwarding targets.
+type ForwardConfig struct {
+	Default string                   `mapstructure:"default"`
+	Targets map[string]ForwardTarget `mapstructure:"targets"`
+}
+
+// ForwardTarget is a named backing embedding model with one or more endpoints.
+type ForwardTarget struct {
+	Endpoints        []EndpointConfig `mapstructure:"endpoints"`
+	Model            string           `mapstructure:"model"`
+	APIKey           string           `mapstructure:"api_key"`
+	APIType          string           `mapstructure:"api_type"`
+	TimeoutSecs      int              `mapstructure:"timeout_secs"`
+	CooldownSecs     int              `mapstructure:"cooldown_secs"`
+	PriorityDecay    int              `mapstructure:"priority_decay"`
+	PriorityRecovery int              `mapstructure:"priority_recovery"`
+}
+
+// EndpointConfig is a single URL within a ForwardTarget.
+type EndpointConfig struct {
+	URL      string `mapstructure:"url"`
+	Priority int    `mapstructure:"priority"`
+	APIKey   string `mapstructure:"api_key"`
+}
+
+// AdapterConfig selects and tunes the dimension adapter.
+type AdapterConfig struct {
+	Type         string `mapstructure:"type"`
+	SourceDim    int    `mapstructure:"source_dim"`
+	TargetDim    int    `mapstructure:"target_dim"`
+	TruncateMode string `mapstructure:"truncate_mode"`
+	PadMode      string `mapstructure:"pad_mode"`
+	Seed         int64  `mapstructure:"seed"`
+	MatrixFile   string `mapstructure:"matrix_file"`
+}
+
+// extensions viper will detect automatically.
+var extensions = []string{"json", "yaml", "toml"}
+
+// ResolveFile returns the config file path that would be used by Load.
+// If cfgFile is non-empty it is returned as-is.
+// Otherwise the default search paths are checked; if no existing file is found,
+// the preferred default (~/.vecna.json) is returned so callers can create it.
+func ResolveFile(cfgFile string) string {
+	if cfgFile != "" {
+		return cfgFile
+	}
+	home, _ := os.UserHomeDir()
+	dirs := []string{".", home, home + "/.config/vecna"}
+	for _, dir := range dirs {
+		for _, ext := range extensions {
+			path := dir + "/vecna." + ext
+			if _, err := os.Stat(path); err == nil {
+				return path
+			}
+		}
+	}
+	return home + "/vecna.json"
+}
+
+// Load reads configuration from the given file path (empty = search defaults),
+// environment variables (prefix VECNA_), and applies built-in defaults.
+func Load(cfgFile string) (*Config, error) {
+	v := viper.New()
+
+	// Defaults
+	v.SetDefault("server.port", 8080)
+	v.SetDefault("server.host", "0.0.0.0")
+	v.SetDefault("metrics.enabled", false)
+	v.SetDefault("metrics.path", "/metrics")
+	v.SetDefault("adapter.type", "truncate")
+	v.SetDefault("adapter.truncate_mode", "from_end")
+	v.SetDefault("adapter.pad_mode", "at_end")
+
+	// Environment
+	v.SetEnvPrefix("VECNA")
+	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
+	v.AutomaticEnv()
+
+	// Config file
+	if cfgFile != "" {
+		v.SetConfigFile(cfgFile)
+	} else {
+		home, _ := os.UserHomeDir()
+		v.SetConfigName("vecna")
+		// No SetConfigType — viper detects format from file extension (json, yaml, toml, etc.)
+		v.AddConfigPath(".")
+		v.AddConfigPath(home)
+		v.AddConfigPath(home + "/.config/vecna")
+	}
+
+	if err := v.ReadInConfig(); err != nil {
+		// Missing config file is acceptable when all required values come from flags/env
+		var notFound viper.ConfigFileNotFoundError
+		if !errors.As(err, &notFound) {
+			return nil, fmt.Errorf("load config: %w", err)
+		}
+	}
+
+	var cfg Config
+	if err := v.Unmarshal(&cfg); err != nil {
+		return nil, fmt.Errorf("unmarshal config: %w", err)
+	}
+
+	applyForwardDefaults(&cfg)
+
+	return &cfg, nil
+}
+
+// applyForwardDefaults fills in zero-value fields on ForwardTarget entries.
+func applyForwardDefaults(cfg *Config) {
+	for name, t := range cfg.Forward.Targets {
+		if t.TimeoutSecs == 0 {
+			t.TimeoutSecs = 30
+		}
+		if t.CooldownSecs == 0 {
+			t.CooldownSecs = 60
+		}
+		if t.PriorityDecay == 0 {
+			t.PriorityDecay = 2
+		}
+		if t.PriorityRecovery == 0 {
+			t.PriorityRecovery = 5
+		}
+		for i, ep := range t.Endpoints {
+			if ep.Priority == 0 {
+				t.Endpoints[i].Priority = 10
+			}
+			if ep.APIKey == "" && t.APIKey != "" {
+				t.Endpoints[i].APIKey = t.APIKey
+			}
+		}
+		cfg.Forward.Targets[name] = t
+	}
+}