feat(delete): real deletes — adapters seeded once into adapter_dir (existing dir is authoritative), sources removed from config.yaml on delete; drop tombstone mechanism for both. Docs: multi-key architecture, gateway_keys as seed

internal/config/config.go

@@ -13,6 +13,7 @@ import (
 
 // Config is the top-level gateway configuration.
 type Config struct {
+	Path          string   `yaml:"-" json:"-"`
 	Listen        string   `yaml:"listen"`
 	GatewayKeys   []string `yaml:"gateway_keys"`
 	DefaultModel  string   `yaml:"default_model"` // e.g. "AUTO" or a model id
@@ -60,12 +61,63 @@ func Load(path string) (*Config, error) {
 	if err := yaml.Unmarshal(data, &cfg); err != nil {
 		return nil, fmt.Errorf("parse config: %w", err)
 	}
+	cfg.Path = path
 	if err := cfg.ApplyDefaults(); err != nil {
 		return nil, err
 	}
 	return &cfg, nil
 }
 
+// RemoveSourceFromYAML deletes the named source entry from the config file so
+// the delete is a real one (no tombstone needed). Uses yaml.Node to preserve
+// the rest of the file's comments and formatting.
+func RemoveSourceFromYAML(path, name string) error {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return err
+	}
+	var doc yaml.Node
+	if err := yaml.Unmarshal(data, &doc); err != nil {
+		return err
+	}
+	content := doc.Content
+	if len(content) == 0 {
+		return nil
+	}
+	root := content[0]
+	if root.Kind != yaml.MappingNode {
+		return nil
+	}
+	for i := 0; i+1 < len(root.Content); i += 2 {
+		key, val := root.Content[i], root.Content[i+1]
+		if key.Value != "sources" || val.Kind != yaml.SequenceNode {
+			continue
+		}
+		kept := val.Content[:0]
+		for _, item := range val.Content {
+			if item.Kind != yaml.MappingNode {
+				continue
+			}
+			found := false
+			for j := 0; j+1 < len(item.Content); j += 2 {
+				if item.Content[j].Value == "name" && item.Content[j+1].Value == name {
+					found = true
+					break
+				}
+			}
+			if !found {
+				kept = append(kept, item)
+			}
+		}
+		val.Content = kept
+	}
+	out, err := yaml.Marshal(&doc)
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(path, out, 0644)
+}
+
 // ApplyDefaults sets missing values and validates the config.
 func (c *Config) ApplyDefaults() error {
 	if c.Listen == "" {