feat(mcp): session id store

internal/mcp/session.go

@@ -0,0 +1,40 @@
+package mcp
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"sync"
+)
+
+type SessionStore struct {
+	mu sync.RWMutex
+	m  map[string]struct{}
+}
+
+func NewSessionStore() *SessionStore {
+	return &SessionStore{m: make(map[string]struct{})}
+}
+
+func (s *SessionStore) Issue() string {
+	b := make([]byte, 16)
+	_, _ = rand.Read(b)
+	id := hex.EncodeToString(b)
+
+	s.mu.Lock()
+	s.m[id] = struct{}{}
+	s.mu.Unlock()
+	return id
+}
+
+func (s *SessionStore) Valid(id string) bool {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	_, ok := s.m[id]
+	return ok
+}
+
+func (s *SessionStore) Drop(id string) {
+	s.mu.Lock()
+	delete(s.m, id)
+	s.mu.Unlock()
+}