POC: Bind AgentCore sessions to one ACS instance using a stable identity

AGENTS.md

@@ -35,6 +35,11 @@ Before starting the implementation or review of any request, you MUST REVIEW the
 - Update API proto: `make update-go-api`
 - Always include `-tags test_dep` when running tests. Include the `integration` tag only for integration tests.
 
+## Code Conventions
+
+- Keep receiver methods in their existing implementation files and unit tests in the corresponding owner test files. Do not create feature files that mix methods or test suites from unrelated owners.
+- Use getter methods for reads whenever available, including protobuf fields. Use direct field access for assignments.
+
 ## Development Workflow
 
 1. Inspect surrounding code, tests, and configuration before making changes.

common/persistence/cassandra/matching_task_store_queue.go

@@ -188,10 +188,10 @@ func (d *taskQueueStore) UpdateTaskQueue(
 
 	if d.version == matchingTaskVersion1 && request.TaskQueueKind == enumspb.TASK_QUEUE_KIND_STICKY {
 		// V1 TTL logic - only applies to V1
-		if request.ExpiryTime == nil {
-			return nil, serviceerror.NewInternal("ExpiryTime cannot be nil for sticky task queue")
+		expiryTTL, ttlErr := taskQueueMetadataTTL(request, time.Now())
+		if ttlErr != nil {
+			return nil, ttlErr
 		}
-		expiryTTL := min(convert.Int64Ceil(time.Until(timestamp.TimeValue(request.ExpiryTime)).Seconds()), maxCassandraTTL)
 		batch := d.Session.NewBatch(gocql.LoggedBatch).WithContext(ctx)
 
 		batch.Query(switchTasksTable(templateUpdateTaskQueueQueryWithTTLPart1, d.version),
@@ -251,6 +251,16 @@ func (d *taskQueueStore) UpdateTaskQueue(
 	return &p.UpdateTaskQueueResponse{}, nil
 }
 
+func taskQueueMetadataTTL(request *p.InternalUpdateTaskQueueRequest, now time.Time) (int64, error) {
+	if request.SingleSessionAssigned {
+		return 0, nil
+	}
+	if request.ExpiryTime == nil {
+		return 0, serviceerror.NewInternal("ExpiryTime cannot be nil for sticky task queue")
+	}
+	return min(convert.Int64Ceil(timestamp.TimeValue(request.ExpiryTime).Sub(now).Seconds()), maxCassandraTTL), nil
+}
+
 func (d *taskQueueStore) ListTaskQueue(
 	_ context.Context,
 	_ *p.ListTaskQueueRequest,

common/persistence/cassandra/matching_task_store_queue_test.go

@@ -0,0 +1,40 @@
+package cassandra
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"go.temporal.io/server/common/persistence"
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+func TestTaskQueueMetadataTTL(t *testing.T) {
+	t.Parallel()
+	now := time.Unix(1000, 0)
+	for _, tc := range []struct {
+		name     string
+		assigned bool
+		expiry   *timestamppb.Timestamp
+		ttl      int64
+		invalid  bool
+	}{
+		{name: "assigned metadata has no ttl", assigned: true},
+		{name: "assignment removes existing ttl", assigned: true, expiry: timestamppb.New(now.Add(time.Hour))},
+		{name: "ordinary sticky requires expiry", invalid: true},
+		{name: "ordinary sticky keeps ttl", expiry: timestamppb.New(now.Add(time.Hour)), ttl: 3600},
+		{name: "fractional ttl rounds up", expiry: timestamppb.New(now.Add(time.Second + time.Millisecond)), ttl: 2},
+		{name: "ttl is capped", expiry: timestamppb.New(now.Add(time.Duration(maxCassandraTTL+3600) * time.Second)), ttl: maxCassandraTTL},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			ttl, err := taskQueueMetadataTTL(&persistence.InternalUpdateTaskQueueRequest{SingleSessionAssigned: tc.assigned, ExpiryTime: tc.expiry}, now)
+			if tc.invalid {
+				require.ErrorContains(t, err, "ExpiryTime cannot be nil")
+				return
+			}
+			require.NoError(t, err)
+			require.Equal(t, tc.ttl, ttl)
+		})
+	}
+}

common/persistence/persistence_interface.go

@@ -271,8 +271,9 @@ type (
 		RangeID       int64
 		TaskQueueInfo *commonpb.DataBlob
 
-		TaskQueueKind enumspb.TaskQueueKind
-		ExpiryTime    *timestamppb.Timestamp
+		TaskQueueKind         enumspb.TaskQueueKind
+		ExpiryTime            *timestamppb.Timestamp
+		SingleSessionAssigned bool
 
 		PrevRangeID int64
 	}