feat: add skill registry with tool routing

internal/registry/registry.go

@@ -0,0 +1,50 @@
+package registry
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+)
+
+// ToolDef describes a single MCP tool exposed by a skill.
+type ToolDef struct {
+	Name        string          `json:"name"`
+	Description string          `json:"description"`
+	InputSchema json.RawMessage `json:"inputSchema"`
+}
+
+// Skill is implemented by each skill package (tdd, review, etc.).
+type Skill interface {
+	Name() string
+	Tools() []ToolDef
+	Handle(ctx context.Context, tool string, args json.RawMessage) (json.RawMessage, error)
+}
+
+// Registry routes MCP tool calls to the correct skill handler.
+type Registry struct {
+	skills map[string]Skill // tool name → skill
+	tools  []ToolDef
+}
+
+func New() *Registry {
+	return &Registry{skills: make(map[string]Skill)}
+}
+
+func (r *Registry) Register(s Skill) {
+	for _, t := range s.Tools() {
+		r.skills[t.Name] = s
+		r.tools = append(r.tools, t)
+	}
+}
+
+func (r *Registry) Tools() []ToolDef {
+	return r.tools
+}
+
+func (r *Registry) Dispatch(ctx context.Context, tool string, args json.RawMessage) (json.RawMessage, error) {
+	s, ok := r.skills[tool]
+	if !ok {
+		return nil, fmt.Errorf("unknown tool: %s", tool)
+	}
+	return s.Handle(ctx, tool, args)
+}