refactor(routing): move session allocation out of router

pkg/session/allocator.go

@@ -0,0 +1,43 @@
+package session
+
+import (
+	"strings"
+
+	"github.com/sipeed/picoclaw/pkg/routing"
+)
+
+// Allocation contains the concrete session keys selected for a routed turn.
+// The current implementation intentionally preserves the legacy session-key
+// layout while moving key construction out of the router.
+type Allocation struct {
+	SessionKey     string
+	MainSessionKey string
+}
+
+// AllocationInput contains the routing result and peer context needed to
+// derive the session keys for a turn.
+type AllocationInput struct {
+	AgentID       string
+	Channel       string
+	AccountID     string
+	Peer          *routing.RoutePeer
+	SessionPolicy routing.SessionPolicy
+}
+
+// AllocateRouteSession maps a route decision onto the current legacy
+// agent-scoped session-key format.
+func AllocateRouteSession(input AllocationInput) Allocation {
+	sessionKey := strings.ToLower(routing.BuildAgentPeerSessionKey(routing.SessionKeyParams{
+		AgentID:       input.AgentID,
+		Channel:       input.Channel,
+		AccountID:     input.AccountID,
+		Peer:          input.Peer,
+		DMScope:       input.SessionPolicy.DMScope,
+		IdentityLinks: input.SessionPolicy.IdentityLinks,
+	}))
+	mainSessionKey := strings.ToLower(routing.BuildAgentMainSessionKey(input.AgentID))
+	return Allocation{
+		SessionKey:     sessionKey,
+		MainSessionKey: mainSessionKey,
+	}
+}