diff --git a/pkg/agent/loop.go b/pkg/agent/loop.go
index 78b91068a..39a2e1539 100644
--- a/pkg/agent/loop.go
+++ b/pkg/agent/loop.go
@@ -27,6 +27,7 @@ import (
 	"github.com/sipeed/picoclaw/pkg/media"
 	"github.com/sipeed/picoclaw/pkg/providers"
 	"github.com/sipeed/picoclaw/pkg/routing"
+	"github.com/sipeed/picoclaw/pkg/session"
 	"github.com/sipeed/picoclaw/pkg/skills"
 	"github.com/sipeed/picoclaw/pkg/state"
 	"github.com/sipeed/picoclaw/pkg/tools"
@@ -672,9 +673,10 @@ func (al *AgentLoop) buildContinuationTarget(msg bus.InboundMessage) (*continuat
 	if err != nil {
 		return nil, err
 	}
+	allocation := al.allocateRouteSession(route, msg)
 
 	return &continuationTarget{
-		SessionKey: resolveScopeKey(route, msg.SessionKey),
+		SessionKey: resolveScopeKey(allocation.SessionKey, msg.SessionKey),
 		Channel:    msg.Channel,
 		ChatID:     msg.ChatID,
 	}, nil
@@ -1323,18 +1325,22 @@ func (al *AgentLoop) processMessage(ctx context.Context, msg bus.InboundMessage)
 		}
 	}
 
-	// Resolve session key from route, while preserving explicit agent-scoped keys.
-	scopeKey := resolveScopeKey(route, msg.SessionKey)
+	allocation := al.allocateRouteSession(route, msg)
+
+	// Resolve session key from the route allocation, while preserving explicit
+	// agent-scoped keys supplied by the caller.
+	scopeKey := resolveScopeKey(allocation.SessionKey, msg.SessionKey)
 	sessionKey := scopeKey
 
 	logger.InfoCF("agent", "Routed message",
 		map[string]any{
-			"agent_id":      agent.ID,
-			"scope_key":     scopeKey,
-			"session_key":   sessionKey,
-			"matched_by":    route.MatchedBy,
-			"route_agent":   route.AgentID,
-			"route_channel": route.Channel,
+			"agent_id":           agent.ID,
+			"scope_key":          scopeKey,
+			"session_key":        sessionKey,
+			"matched_by":         route.MatchedBy,
+			"route_agent":        route.AgentID,
+			"route_channel":      route.Channel,
+			"route_main_session": allocation.MainSessionKey,
 		})
 
 	opts := processOptions{
@@ -1401,11 +1407,21 @@ func normalizedInboundContext(msg bus.InboundMessage) bus.InboundContext {
 	return bus.NormalizeInboundMessage(msg).Context
 }
 
-func resolveScopeKey(route routing.ResolvedRoute, msgSessionKey string) string {
+func resolveScopeKey(routeSessionKey, msgSessionKey string) string {
 	if msgSessionKey != "" && strings.HasPrefix(msgSessionKey, sessionKeyAgentPrefix) {
 		return msgSessionKey
 	}
-	return route.SessionKey
+	return routeSessionKey
+}
+
+func (al *AgentLoop) allocateRouteSession(route routing.ResolvedRoute, msg bus.InboundMessage) session.Allocation {
+	return session.AllocateRouteSession(session.AllocationInput{
+		AgentID:       route.AgentID,
+		Channel:       route.Channel,
+		AccountID:     route.AccountID,
+		Peer:          extractPeer(msg),
+		SessionPolicy: route.SessionPolicy,
+	})
 }
 
 func (al *AgentLoop) resolveSteeringTarget(msg bus.InboundMessage) (string, string, bool) {
@@ -1417,8 +1433,9 @@ func (al *AgentLoop) resolveSteeringTarget(msg bus.InboundMessage) (string, stri
 	if err != nil || agent == nil {
 		return "", "", false
 	}
+	allocation := al.allocateRouteSession(route, msg)
 
-	return resolveScopeKey(route, msg.SessionKey), agent.ID, true
+	return resolveScopeKey(allocation.SessionKey, msg.SessionKey), agent.ID, true
 }
 
 func (al *AgentLoop) requeueInboundMessage(msg bus.InboundMessage) error {
diff --git a/pkg/agent/loop_test.go b/pkg/agent/loop_test.go
index 54235b23a..1f99a5085 100644
--- a/pkg/agent/loop_test.go
+++ b/pkg/agent/loop_test.go
@@ -670,7 +670,12 @@ func TestProcessMessage_MediaToolHandledSkipsFollowUpLLMAndFinalText(t *testing.
 	if err != nil {
 		t.Fatalf("resolveMessageRoute() error = %v", err)
 	}
-	sessionKey := resolveScopeKey(route, "")
+	sessionKey := resolveScopeKey(al.allocateRouteSession(route, bus.InboundMessage{
+		Channel:  "telegram",
+		ChatID:   "chat1",
+		SenderID: "user1",
+		Content:  "take a screenshot of the screen and send it to me",
+	}).SessionKey, "")
 	history := defaultAgent.Sessions.GetHistory(sessionKey)
 	if len(history) == 0 {
 		t.Fatal("expected session history to be saved")
@@ -1492,7 +1497,7 @@ func TestProcessMessage_UsesRouteSessionKey(t *testing.T) {
 		Channel: msg.Channel,
 		Peer:    extractPeer(msg),
 	})
-	sessionKey := route.SessionKey
+	sessionKey := al.allocateRouteSession(route, msg).SessionKey
 
 	defaultAgent := al.registry.GetDefaultAgent()
 	if defaultAgent == nil {
@@ -2195,7 +2200,15 @@ func TestAgentLoop_ToolLimitUsesDedicatedFallback(t *testing.T) {
 			ID:   "cron",
 		},
 	})
-	history := defaultAgent.Sessions.GetHistory(route.SessionKey)
+	history := defaultAgent.Sessions.GetHistory(al.allocateRouteSession(route, bus.InboundMessage{
+		Channel:  "test",
+		SenderID: "cron",
+		ChatID:   "chat1",
+		Peer: bus.Peer{
+			Kind: "direct",
+			ID:   "cron",
+		},
+	}).SessionKey)
 	if len(history) != 4 {
 		t.Fatalf("history len = %d, want 4", len(history))
 	}
diff --git a/pkg/routing/route.go b/pkg/routing/route.go
index 9eb060c53..494aefabb 100644
--- a/pkg/routing/route.go
+++ b/pkg/routing/route.go
@@ -16,14 +16,21 @@ type RouteInput struct {
 	TeamID     string
 }
 
+// SessionPolicy describes how a routed message should be mapped to a session.
+// The current implementation preserves the legacy dm_scope and identity_link
+// semantics while moving session-key construction out of the router.
+type SessionPolicy struct {
+	DMScope       DMScope
+	IdentityLinks map[string][]string
+}
+
 // ResolvedRoute is the result of agent routing.
 type ResolvedRoute struct {
-	AgentID        string
-	Channel        string
-	AccountID      string
-	SessionKey     string
-	MainSessionKey string
-	MatchedBy      string // "binding.peer", "binding.peer.parent", "binding.guild", "binding.team", "binding.account", "binding.channel", "default"
+	AgentID       string
+	Channel       string
+	AccountID     string
+	SessionPolicy SessionPolicy
+	MatchedBy     string // "binding.peer", "binding.peer.parent", "binding.guild", "binding.team", "binding.account", "binding.channel", "default"
 }
 
 // RouteResolver determines which agent handles a message based on config bindings.
@@ -36,7 +43,8 @@ func NewRouteResolver(cfg *config.Config) *RouteResolver {
 	return &RouteResolver{cfg: cfg}
 }
 
-// ResolveRoute determines which agent handles the message and constructs session keys.
+// ResolveRoute determines which agent handles the message and returns the
+// session policy that should be used to allocate session state.
 // Implements the 7-level priority cascade:
 // peer > parent_peer > guild > team > account > channel_wildcard > default
 func (r *RouteResolver) ResolveRoute(input RouteInput) ResolvedRoute {
@@ -44,32 +52,18 @@ func (r *RouteResolver) ResolveRoute(input RouteInput) ResolvedRoute {
 	accountID := NormalizeAccountID(input.AccountID)
 	peer := input.Peer
 
-	dmScope := DMScope(r.cfg.Session.DMScope)
-	if dmScope == "" {
-		dmScope = DMScopeMain
-	}
-	identityLinks := r.cfg.Session.IdentityLinks
+	sessionPolicy := r.sessionPolicy()
 
 	bindings := r.filterBindings(channel, accountID)
 
 	choose := func(agentID string, matchedBy string) ResolvedRoute {
 		resolvedAgentID := r.pickAgentID(agentID)
-		sessionKey := strings.ToLower(BuildAgentPeerSessionKey(SessionKeyParams{
+		return ResolvedRoute{
 			AgentID:       resolvedAgentID,
 			Channel:       channel,
 			AccountID:     accountID,
-			Peer:          peer,
-			DMScope:       dmScope,
-			IdentityLinks: identityLinks,
-		}))
-		mainSessionKey := strings.ToLower(BuildAgentMainSessionKey(resolvedAgentID))
-		return ResolvedRoute{
-			AgentID:        resolvedAgentID,
-			Channel:        channel,
-			AccountID:      accountID,
-			SessionKey:     sessionKey,
-			MainSessionKey: mainSessionKey,
-			MatchedBy:      matchedBy,
+			SessionPolicy: sessionPolicy,
+			MatchedBy:     matchedBy,
 		}
 	}
 
@@ -250,3 +244,27 @@ func (r *RouteResolver) resolveDefaultAgentID() string {
 	}
 	return DefaultAgentID
 }
+
+func (r *RouteResolver) sessionPolicy() SessionPolicy {
+	dmScope := DMScope(r.cfg.Session.DMScope)
+	if dmScope == "" {
+		dmScope = DMScopeMain
+	}
+	return SessionPolicy{
+		DMScope:       dmScope,
+		IdentityLinks: cloneIdentityLinks(r.cfg.Session.IdentityLinks),
+	}
+}
+
+func cloneIdentityLinks(src map[string][]string) map[string][]string {
+	if len(src) == 0 {
+		return nil
+	}
+	cloned := make(map[string][]string, len(src))
+	for canonical, ids := range src {
+		dup := make([]string, len(ids))
+		copy(dup, ids)
+		cloned[canonical] = dup
+	}
+	return cloned
+}
diff --git a/pkg/routing/route_test.go b/pkg/routing/route_test.go
index fdfc899f9..ab1a7a4e2 100644
--- a/pkg/routing/route_test.go
+++ b/pkg/routing/route_test.go
@@ -37,6 +37,12 @@ func TestResolveRoute_DefaultAgent_NoBindings(t *testing.T) {
 	if route.MatchedBy != "default" {
 		t.Errorf("MatchedBy = %q, want 'default'", route.MatchedBy)
 	}
+	if route.SessionPolicy.DMScope != DMScopePerPeer {
+		t.Errorf("SessionPolicy.DMScope = %q, want %q", route.SessionPolicy.DMScope, DMScopePerPeer)
+	}
+	if route.SessionPolicy.IdentityLinks != nil {
+		t.Errorf("SessionPolicy.IdentityLinks = %v, want nil", route.SessionPolicy.IdentityLinks)
+	}
 }
 
 func TestResolveRoute_PeerBinding(t *testing.T) {
diff --git a/pkg/session/allocator.go b/pkg/session/allocator.go
new file mode 100644
index 000000000..675e577f8
--- /dev/null
+++ b/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,
+	}
+}
diff --git a/pkg/session/allocator_test.go b/pkg/session/allocator_test.go
new file mode 100644
index 000000000..a6e84e09d
--- /dev/null
+++ b/pkg/session/allocator_test.go
@@ -0,0 +1,51 @@
+package session
+
+import (
+	"testing"
+
+	"github.com/sipeed/picoclaw/pkg/routing"
+)
+
+func TestAllocateRouteSession_PerPeerDM(t *testing.T) {
+	allocation := AllocateRouteSession(AllocationInput{
+		AgentID:   "main",
+		Channel:   "telegram",
+		AccountID: "default",
+		Peer: &routing.RoutePeer{
+			Kind: "direct",
+			ID:   "User123",
+		},
+		SessionPolicy: routing.SessionPolicy{
+			DMScope: routing.DMScopePerPeer,
+		},
+	})
+
+	if allocation.SessionKey != "agent:main:direct:user123" {
+		t.Fatalf("SessionKey = %q, want %q", allocation.SessionKey, "agent:main:direct:user123")
+	}
+	if allocation.MainSessionKey != "agent:main:main" {
+		t.Fatalf("MainSessionKey = %q, want %q", allocation.MainSessionKey, "agent:main:main")
+	}
+}
+
+func TestAllocateRouteSession_GroupPeer(t *testing.T) {
+	allocation := AllocateRouteSession(AllocationInput{
+		AgentID:   "main",
+		Channel:   "slack",
+		AccountID: "workspace-a",
+		Peer: &routing.RoutePeer{
+			Kind: "channel",
+			ID:   "C001",
+		},
+		SessionPolicy: routing.SessionPolicy{
+			DMScope: routing.DMScopePerAccountChannelPeer,
+		},
+	})
+
+	if allocation.SessionKey != "agent:main:slack:channel:c001" {
+		t.Fatalf("SessionKey = %q, want %q", allocation.SessionKey, "agent:main:slack:channel:c001")
+	}
+	if allocation.MainSessionKey != "agent:main:main" {
+		t.Fatalf("MainSessionKey = %q, want %q", allocation.MainSessionKey, "agent:main:main")
+	}
+}