test(config): add migration tests for litellm provider

* Implement tests for migrating configuration from v1 to v2 for the litellm provider.
* Validate the structure and values of the migrated configuration.
* Ensure migration rejects newer versions of the configuration.
fix(validate): enhance AI provider validation logic
* Consolidate provider validation into a dedicated method.
* Ensure at least one provider is specified and validate its type.
* Check for required fields based on provider type.
fix(mcpserver): update tool set to use new enrichment tool
* Replace RetryMetadataTool with RetryEnrichmentTool in the ToolSet.
fix(tools): refactor tools to use embedding and metadata runners
* Update tools to utilize EmbeddingRunner and MetadataRunner instead of Provider.
* Adjust method calls to align with the new runner interfaces.

internal/ai/registry.go

@@ -0,0 +1,96 @@
+package ai
+
+import (
+	"fmt"
+	"log/slog"
+	"net/http"
+	"strings"
+
+	"git.warky.dev/wdevs/amcs/internal/ai/compat"
+	"git.warky.dev/wdevs/amcs/internal/config"
+)
+
+// Registry holds one compat.Client per named provider. Runners look up clients
+// by provider name when walking a role chain.
+type Registry struct {
+	clients map[string]*compat.Client
+}
+
+// NewRegistry builds a Registry from the configured providers. Each provider
+// type maps onto a compat.Client with type-specific header plumbing (e.g.
+// openrouter's HTTP-Referer / X-Title).
+func NewRegistry(providers map[string]config.ProviderConfig, httpClient *http.Client, log *slog.Logger) (*Registry, error) {
+	if httpClient == nil {
+		return nil, fmt.Errorf("ai registry: http client is required")
+	}
+	if len(providers) == 0 {
+		return nil, fmt.Errorf("ai registry: no providers configured")
+	}
+
+	clients := make(map[string]*compat.Client, len(providers))
+	for name, p := range providers {
+		headers, err := providerHeaders(p)
+		if err != nil {
+			return nil, fmt.Errorf("ai registry: provider %q: %w", name, err)
+		}
+		clients[name] = compat.New(compat.Config{
+			Name:       name,
+			BaseURL:    p.BaseURL,
+			APIKey:     p.APIKey,
+			Headers:    headers,
+			HTTPClient: httpClient,
+			Log:        log,
+		})
+	}
+	return &Registry{clients: clients}, nil
+}
+
+// Client returns the compat.Client registered under name.
+func (r *Registry) Client(name string) (*compat.Client, error) {
+	c, ok := r.clients[name]
+	if !ok {
+		return nil, fmt.Errorf("ai registry: provider %q is not configured", name)
+	}
+	return c, nil
+}
+
+// Names returns the registered provider names.
+func (r *Registry) Names() []string {
+	names := make([]string, 0, len(r.clients))
+	for name := range r.clients {
+		names = append(names, name)
+	}
+	return names
+}
+
+func providerHeaders(p config.ProviderConfig) (map[string]string, error) {
+	switch p.Type {
+	case "litellm", "ollama":
+		return cloneHeaders(p.RequestHeaders), nil
+	case "openrouter":
+		headers := cloneHeaders(p.RequestHeaders)
+		if headers == nil {
+			headers = map[string]string{}
+		}
+		if s := strings.TrimSpace(p.SiteURL); s != "" {
+			headers["HTTP-Referer"] = s
+		}
+		if s := strings.TrimSpace(p.AppName); s != "" {
+			headers["X-Title"] = s
+		}
+		return headers, nil
+	default:
+		return nil, fmt.Errorf("unsupported provider type %q", p.Type)
+	}
+}
+
+func cloneHeaders(in map[string]string) map[string]string {
+	if len(in) == 0 {
+		return nil
+	}
+	out := make(map[string]string, len(in))
+	for k, v := range in {
+		out[k] = v
+	}
+	return out
+}