diff --git a/quic/api/test/QuicPacketSchedulerTest.cpp b/quic/api/test/QuicPacketSchedulerTest.cpp
index a97c376f2..4552ee672 100644
--- a/quic/api/test/QuicPacketSchedulerTest.cpp
+++ b/quic/api/test/QuicPacketSchedulerTest.cpp
@@ -82,7 +82,18 @@ PacketNum addInitialOutstandingPacket(QuicConnectionStateBase& conn) {
       QuicVersion::QUIC_DRAFT);
   RegularQuicWritePacket packet(std::move(header));
   conn.outstandings.packets.emplace_back(
-      packet, Clock::now(), 0, 0, true, 0, 0, 0, 0, LossState(), 0);
+      packet,
+      Clock::now(),
+      0,
+      0,
+      true,
+      0,
+      0,
+      0,
+      0,
+      LossState(),
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   conn.outstandings.packetCount[PacketNumberSpace::Initial]++;
   increaseNextPacketNum(conn, PacketNumberSpace::Initial);
   return nextPacketNum;
@@ -101,7 +112,18 @@ PacketNum addHandshakeOutstandingPacket(QuicConnectionStateBase& conn) {
       QuicVersion::QUIC_DRAFT);
   RegularQuicWritePacket packet(std::move(header));
   conn.outstandings.packets.emplace_back(
-      packet, Clock::now(), 0, 0, true, 0, 0, 0, 0, LossState(), 0);
+      packet,
+      Clock::now(),
+      0,
+      0,
+      true,
+      0,
+      0,
+      0,
+      0,
+      LossState(),
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   conn.outstandings.packetCount[PacketNumberSpace::Handshake]++;
   increaseNextPacketNum(conn, PacketNumberSpace::Handshake);
   return nextPacketNum;
@@ -115,7 +137,18 @@ PacketNum addOutstandingPacket(QuicConnectionStateBase& conn) {
       nextPacketNum);
   RegularQuicWritePacket packet(std::move(header));
   conn.outstandings.packets.emplace_back(
-      packet, Clock::now(), 0, 0, false, 0, 0, 0, 0, LossState(), 0);
+      packet,
+      Clock::now(),
+      0,
+      0,
+      false,
+      0,
+      0,
+      0,
+      0,
+      LossState(),
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   increaseNextPacketNum(conn, PacketNumberSpace::AppData);
   return nextPacketNum;
 }
diff --git a/quic/api/test/QuicTransportFunctionsTest.cpp b/quic/api/test/QuicTransportFunctionsTest.cpp
index 6aa44c5af..37202bd54 100644
--- a/quic/api/test/QuicTransportFunctionsTest.cpp
+++ b/quic/api/test/QuicTransportFunctionsTest.cpp
@@ -1681,11 +1681,10 @@ TEST_F(QuicTransportFunctionsTest, TestStreamDetailsControlPacket) {
   // If we have only control frames sent, there should be no stream data in the
   // outstanding packet.
   ASSERT_EQ(1, conn->outstandings.packets.size());
-  auto detailsPerStream =
+  const auto& detailsPerStream =
       getFirstOutstandingPacket(*conn, PacketNumberSpace::AppData)
-          ->metadata.maybeDetailsPerStream;
-  EXPECT_EQ(true, detailsPerStream.has_value());
-  EXPECT_EQ(0, detailsPerStream->getDetails().size());
+          ->metadata.detailsPerStream.getDetails();
+  EXPECT_EQ(0, detailsPerStream.size());
 }
 
 TEST_F(QuicTransportFunctionsTest, TestStreamDetailsAppDataPacketSingleStream) {
@@ -1708,7 +1707,7 @@ TEST_F(QuicTransportFunctionsTest, TestStreamDetailsAppDataPacketSingleStream) {
   ASSERT_EQ(1, conn->outstandings.packets.size());
   auto detailsPerStream =
       getFirstOutstandingPacket(*conn, PacketNumberSpace::AppData)
-          ->metadata.maybeDetailsPerStream->getDetails();
+          ->metadata.detailsPerStream.getDetails();
   EXPECT_EQ(1, detailsPerStream.size());
   auto streamDetail = detailsPerStream[stream->id];
   EXPECT_EQ(false, streamDetail.finObserved);
@@ -1743,7 +1742,7 @@ TEST_F(
   ASSERT_EQ(1, conn->outstandings.packets.size());
   auto detailsPerStream =
       getFirstOutstandingPacket(*conn, PacketNumberSpace::AppData)
-          ->metadata.maybeDetailsPerStream->getDetails();
+          ->metadata.detailsPerStream.getDetails();
   EXPECT_EQ(1, detailsPerStream.size());
   auto streamDetail = detailsPerStream[stream->id];
   EXPECT_EQ(true, streamDetail.finObserved);
@@ -1778,7 +1777,7 @@ TEST_F(
   // The first outstanding packet is the one with new data
   auto detailsPerStream =
       getFirstOutstandingPacket(*conn, PacketNumberSpace::AppData)
-          ->metadata.maybeDetailsPerStream->getDetails();
+          ->metadata.detailsPerStream.getDetails();
   EXPECT_EQ(1, detailsPerStream.size());
   auto streamDetail = detailsPerStream[stream->id];
   EXPECT_EQ(false, streamDetail.finObserved);
@@ -1802,7 +1801,7 @@ TEST_F(
 
   // The second outstanding packet is the one with retransmit data
   detailsPerStream = getLastOutstandingPacket(*conn, PacketNumberSpace::AppData)
-                         ->metadata.maybeDetailsPerStream->getDetails();
+                         ->metadata.detailsPerStream.getDetails();
   EXPECT_EQ(1, detailsPerStream.size());
   streamDetail = detailsPerStream[stream->id];
   EXPECT_EQ(false, streamDetail.finObserved);
@@ -1832,7 +1831,7 @@ TEST_F(
 
   // The third outstanding packet will have both new and retransmitted data.
   detailsPerStream = getLastOutstandingPacket(*conn, PacketNumberSpace::AppData)
-                         ->metadata.maybeDetailsPerStream->getDetails();
+                         ->metadata.detailsPerStream.getDetails();
   EXPECT_EQ(1, detailsPerStream.size());
   streamDetail = detailsPerStream[stream->id];
   EXPECT_EQ(false, streamDetail.finObserved);
@@ -1857,7 +1856,7 @@ TEST_F(
 
   // The forth outstanding packet will have only retransmit data.
   detailsPerStream = getLastOutstandingPacket(*conn, PacketNumberSpace::AppData)
-                         ->metadata.maybeDetailsPerStream->getDetails();
+                         ->metadata.detailsPerStream.getDetails();
   EXPECT_EQ(1, detailsPerStream.size());
   streamDetail = detailsPerStream[stream->id];
   EXPECT_EQ(false, streamDetail.finObserved);
@@ -1901,7 +1900,7 @@ TEST_F(
   ASSERT_EQ(1, conn->outstandings.packets.size());
   auto detailsPerStream =
       getFirstOutstandingPacket(*conn, PacketNumberSpace::AppData)
-          ->metadata.maybeDetailsPerStream->getDetails();
+          ->metadata.detailsPerStream.getDetails();
   EXPECT_EQ(2, detailsPerStream.size());
   auto stream1Detail = detailsPerStream[stream1Id];
   auto stream2Detail = detailsPerStream[stream2Id];
diff --git a/quic/codec/test/QuicPacketRebuilderTest.cpp b/quic/codec/test/QuicPacketRebuilderTest.cpp
index d753226d4..720bd5b19 100644
--- a/quic/codec/test/QuicPacketRebuilderTest.cpp
+++ b/quic/codec/test/QuicPacketRebuilderTest.cpp
@@ -39,7 +39,8 @@ OutstandingPacket makeDummyOutstandingPacket(
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   return packet;
 }
 
diff --git a/quic/common/test/TestUtils.cpp b/quic/common/test/TestUtils.cpp
index 9c263b22e..a0eeb9602 100644
--- a/quic/common/test/TestUtils.cpp
+++ b/quic/common/test/TestUtils.cpp
@@ -547,7 +547,8 @@ OutstandingPacket makeTestingWritePacket(
       inflightBytes,
       0,
       LossState(),
-      writeCount);
+      writeCount,
+      OutstandingPacketMetadata::DetailsPerStream());
 }
 
 CongestionController::AckEvent makeAck(
@@ -576,8 +577,7 @@ CongestionController::AckEvent makeAck(
               0 /* numOutstanding */,
               LossState() /* lossState */,
               0 /* writeCount */,
-              folly::none /* detailsPerStream) */
-              ))
+              OutstandingPacketMetadata::DetailsPerStream()))
           .build());
   ack.largestAckedPacketSentTime = sentTime;
   return ack;
diff --git a/quic/congestion_control/test/CopaTest.cpp b/quic/congestion_control/test/CopaTest.cpp
index e20559660..ba9870460 100644
--- a/quic/congestion_control/test/CopaTest.cpp
+++ b/quic/congestion_control/test/CopaTest.cpp
@@ -41,7 +41,8 @@ class CopaTest : public Test {
           0,
           0,
           LossState(),
-          0));
+          0,
+          OutstandingPacketMetadata::DetailsPerStream()));
       loss.lostBytes = packetData.second;
     }
     loss.lostPackets = lostPackets.size();
@@ -67,7 +68,8 @@ class CopaTest : public Test {
         inflight,
         0,
         LossState(),
-        0);
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
   }
 
   CongestionController::AckEvent createAckEvent(
diff --git a/quic/congestion_control/test/NewRenoTest.cpp b/quic/congestion_control/test/NewRenoTest.cpp
index 1f49b22e7..3979ed0d6 100644
--- a/quic/congestion_control/test/NewRenoTest.cpp
+++ b/quic/congestion_control/test/NewRenoTest.cpp
@@ -37,7 +37,8 @@ CongestionController::LossEvent createLossEvent(
         0,
         0,
         LossState(),
-        0));
+        0,
+        OutstandingPacketMetadata::DetailsPerStream()));
     loss.lostBytes = packetData.second;
   }
   loss.lostPackets = lostPackets.size();
@@ -66,7 +67,8 @@ CongestionController::AckEvent createAckEvent(
           0,
           0,
           LossState(),
-          0)));
+          0,
+          OutstandingPacketMetadata::DetailsPerStream())));
   return ack;
 }
 
@@ -89,7 +91,8 @@ OutstandingPacket createPacket(
       inflight,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 }
 
 TEST_F(NewRenoTest, TestLoss) {
diff --git a/quic/d6d/test/QuicD6DStateFunctionsTest.cpp b/quic/d6d/test/QuicD6DStateFunctionsTest.cpp
index 28a39cd27..33dca1782 100644
--- a/quic/d6d/test/QuicD6DStateFunctionsTest.cpp
+++ b/quic/d6d/test/QuicD6DStateFunctionsTest.cpp
@@ -212,7 +212,8 @@ TEST_F(QuicD6DStateFunctionsTest, D6DProbeAckedInBase) {
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   d6d.lastProbe = D6DProbePacket(
       pkt.packet.header.getPacketSequenceNum(), pkt.metadata.encodedSize);
   d6d.raiser = std::make_unique<MockProbeSizeRaiser>();
@@ -260,7 +261,8 @@ TEST_F(QuicD6DStateFunctionsTest, D6DProbeAckedInSearchingOne) {
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   d6d.lastProbe = D6DProbePacket(
       pkt.packet.header.getPacketSequenceNum(), pkt.metadata.encodedSize);
   d6d.raiser = std::make_unique<MockProbeSizeRaiser>();
@@ -309,7 +311,8 @@ TEST_F(QuicD6DStateFunctionsTest, D6DProbeAckedInSearchingMax) {
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   d6d.lastProbe = D6DProbePacket(
       pkt.packet.header.getPacketSequenceNum(), pkt.metadata.encodedSize);
   d6d.raiser = std::make_unique<MockProbeSizeRaiser>();
@@ -366,7 +369,8 @@ TEST_F(QuicD6DStateFunctionsTest, D6DProbeAckedInError) {
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   d6d.lastProbe = D6DProbePacket(
       pkt.packet.header.getPacketSequenceNum(), pkt.metadata.encodedSize);
   d6d.raiser = std::make_unique<MockProbeSizeRaiser>();
@@ -413,7 +417,8 @@ TEST_F(QuicD6DStateFunctionsTest, BlackholeInSearching) {
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   d6d.lastProbe = D6DProbePacket(
       pkt.packet.header.getPacketSequenceNum(), pkt.metadata.encodedSize);
 
@@ -428,7 +433,8 @@ TEST_F(QuicD6DStateFunctionsTest, BlackholeInSearching) {
       conn.udpSendPacketLen + d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   d6d.thresholdCounter = std::make_unique<WindowedCounter<uint64_t, uint64_t>>(
       std::chrono::microseconds(kDefaultD6DBlackholeDetectionWindow).count(),
@@ -487,7 +493,9 @@ TEST_F(QuicD6DStateFunctionsTest, BlackholeInSearchComplete) {
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
+
   d6d.lastProbe = D6DProbePacket(
       pkt.packet.header.getPacketSequenceNum(), pkt.metadata.encodedSize);
 
@@ -502,7 +510,8 @@ TEST_F(QuicD6DStateFunctionsTest, BlackholeInSearchComplete) {
       conn.udpSendPacketLen + d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   d6d.thresholdCounter = std::make_unique<WindowedCounter<uint64_t, uint64_t>>(
       std::chrono::microseconds(kDefaultD6DBlackholeDetectionWindow).count(),
@@ -564,7 +573,8 @@ TEST_F(QuicD6DStateFunctionsTest, ReachMaxPMTU) {
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   d6d.lastProbe = D6DProbePacket(
       pkt.packet.header.getPacketSequenceNum(), pkt.metadata.encodedSize);
   d6d.raiser = std::make_unique<MockProbeSizeRaiser>();
@@ -605,7 +615,8 @@ TEST_F(
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   d6d.lastProbe = D6DProbePacket(
       pkt.packet.header.getPacketSequenceNum(), pkt.metadata.encodedSize);
   d6d.raiser = std::make_unique<MockProbeSizeRaiser>();
@@ -628,7 +639,8 @@ TEST_F(
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   // Generate a false positive blackhole signal
   detectPMTUBlackhole(conn, lostPacket);
   EXPECT_EQ(d6d.state, D6DMachineState::BASE);
@@ -668,7 +680,8 @@ TEST_F(QuicD6DStateFunctionsTest, UpperboundIsBase) {
       d6d.currentProbeSize,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   d6d.lastProbe = D6DProbePacket(
       pkt.packet.header.getPacketSequenceNum(), pkt.metadata.encodedSize);
   d6d.raiser = std::make_unique<MockProbeSizeRaiser>();
diff --git a/quic/loss/test/QuicLossFunctionsTest.cpp b/quic/loss/test/QuicLossFunctionsTest.cpp
index dee7830e9..cf8754672 100644
--- a/quic/loss/test/QuicLossFunctionsTest.cpp
+++ b/quic/loss/test/QuicLossFunctionsTest.cpp
@@ -256,7 +256,8 @@ PacketNum QuicLossFunctionsTest::sendPacket(
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   outstandingPacket.associatedEvent = associatedEvent;
   conn.lossState.lastRetransmittablePacketSentTime = time;
   if (conn.congestionController) {
@@ -1007,8 +1008,19 @@ TEST_F(QuicLossFunctionsTest, TestHandleAckForLoss) {
       conn->version.value());
   RegularQuicWritePacket outstandingRegularPacket(std::move(longHeader));
   auto now = Clock::now();
-  conn->outstandings.packets.emplace_back(OutstandingPacket(
-      outstandingRegularPacket, now, 0, 0, false, 0, 0, 0, 0, LossState(), 0));
+  conn->outstandings.packets.emplace_back(
+      outstandingRegularPacket,
+      now,
+      0,
+      0,
+      false,
+      0,
+      0,
+      0,
+      0,
+      LossState(),
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   conn->outstandings.packetCount[PacketNumberSpace::Handshake]++;
 
   bool testLossMarkFuncCalled = false;
@@ -1889,8 +1901,7 @@ TEST_F(QuicLossFunctionsTest, PersistentCongestionAckOutsideWindow) {
               0 /* numOutstanding */,
               LossState() /* lossState */,
               0 /* writeCount */,
-              folly::none /* detailsPerStream) */
-              ))
+              OutstandingPacketMetadata::DetailsPerStream()))
           .build());
 
   EXPECT_TRUE(isPersistentCongestion(
@@ -1917,8 +1928,7 @@ TEST_F(QuicLossFunctionsTest, PersistentCongestionAckInsideWindow) {
               0 /* numOutstanding */,
               LossState() /* lossState */,
               0 /* writeCount */,
-              folly::none /* detailsPerStream) */
-              ))
+              OutstandingPacketMetadata::DetailsPerStream()))
           .build());
 
   EXPECT_FALSE(isPersistentCongestion(
@@ -1944,8 +1954,7 @@ TEST_F(QuicLossFunctionsTest, PersistentCongestionNoPTO) {
               0 /* numOutstanding */,
               LossState() /* lossState */,
               0 /* writeCount */,
-              folly::none /* detailsPerStream) */
-              ))
+              OutstandingPacketMetadata::DetailsPerStream()))
           .build());
 
   EXPECT_FALSE(isPersistentCongestion(
diff --git a/quic/state/OutstandingPacket.h b/quic/state/OutstandingPacket.h
index 9abf01ace..8dc4c9adf 100644
--- a/quic/state/OutstandingPacket.h
+++ b/quic/state/OutstandingPacket.h
@@ -96,8 +96,8 @@ struct OutstandingPacketMetadata {
     folly::F14FastMap<StreamId, StreamDetails> detailsPerStream;
   };
 
-  // When enabled, details about each stream with frames in this packet
-  folly::Optional<DetailsPerStream> maybeDetailsPerStream;
+  // Details about each stream with frames in this packet
+  DetailsPerStream detailsPerStream;
 
   OutstandingPacketMetadata(
       TimePoint timeIn,
@@ -111,7 +111,7 @@ struct OutstandingPacketMetadata {
       uint64_t packetsInflightIn,
       const LossState& lossStateIn,
       uint64_t writeCount,
-      folly::Optional<DetailsPerStream> maybeDetailsPerStream)
+      DetailsPerStream detailsPerStream)
       : time(timeIn),
         encodedSize(encodedSizeIn),
         encodedBodySize(encodedBodySizeIn),
@@ -124,7 +124,7 @@ struct OutstandingPacketMetadata {
         totalPacketsSent(lossStateIn.totalPacketsSent),
         totalAckElicitingPacketsSent(lossStateIn.totalAckElicitingPacketsSent),
         writeCount(writeCount),
-        maybeDetailsPerStream(std::move(maybeDetailsPerStream)) {}
+        detailsPerStream(std::move(detailsPerStream)) {}
 };
 
 // Data structure to represent outstanding retransmittable packets
@@ -198,8 +198,7 @@ struct OutstandingPacket {
       uint64_t packetsInflightIn,
       const LossState& lossStateIn,
       uint64_t writeCount,
-      folly::Optional<Metadata::DetailsPerStream> maybeDetailsPerStream =
-          folly::none)
+      Metadata::DetailsPerStream detailsPerStream)
       : packet(std::move(packetIn)),
         metadata(OutstandingPacketMetadata(
             timeIn,
@@ -213,7 +212,7 @@ struct OutstandingPacket {
             packetsInflightIn,
             lossStateIn,
             writeCount,
-            std::move(maybeDetailsPerStream))) {}
+            std::move(detailsPerStream))) {}
 
   OutstandingPacket(
       RegularQuicWritePacket packetIn,
@@ -228,8 +227,7 @@ struct OutstandingPacket {
       uint64_t packetsInflightIn,
       const LossState& lossStateIn,
       uint64_t writeCount,
-      folly::Optional<Metadata::DetailsPerStream> maybeDetailsPerStream =
-          folly::none)
+      Metadata::DetailsPerStream detailsPerStream)
       : packet(std::move(packetIn)),
         metadata(OutstandingPacketMetadata(
             timeIn,
@@ -243,6 +241,6 @@ struct OutstandingPacket {
             packetsInflightIn,
             lossStateIn,
             writeCount,
-            std::move(maybeDetailsPerStream))) {}
+            std::move(detailsPerStream))) {}
 };
 } // namespace quic
diff --git a/quic/state/test/AckHandlersTest.cpp b/quic/state/test/AckHandlersTest.cpp
index 664e20eba..0d2feb82c 100644
--- a/quic/state/test/AckHandlersTest.cpp
+++ b/quic/state/test/AckHandlersTest.cpp
@@ -65,7 +65,8 @@ auto emplacePackets(
         packetNum + 1,
         packetNum + 1,
         quic::LossState(),
-        0);
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
     conn.outstandings.packets.emplace_back(sentPacket);
     packetNum++;
   }
@@ -90,7 +91,7 @@ TEST_P(AckHandlersTest, TestAckMultipleSequentialBlocks) {
     regularPacket.frames.emplace_back(std::move(frame));
     conn.outstandings
         .packetCount[regularPacket.header.getPacketNumberSpace()]++;
-    conn.outstandings.packets.emplace_back(OutstandingPacket(
+    conn.outstandings.packets.emplace_back(
         std::move(regularPacket),
         sentTime,
         1,
@@ -101,7 +102,8 @@ TEST_P(AckHandlersTest, TestAckMultipleSequentialBlocks) {
         0,
         0,
         LossState(),
-        0));
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
   }
   ReadAckFrame ackFrame;
   ackFrame.largestAcked = 101;
@@ -173,7 +175,7 @@ TEST_P(AckHandlersTest, TestAckMultipleSequentialBlocksLoss) {
     regularPacket.frames.emplace_back(std::move(frame));
     conn.outstandings
         .packetCount[regularPacket.header.getPacketNumberSpace()]++;
-    conn.outstandings.packets.emplace_back(OutstandingPacket(
+    conn.outstandings.packets.emplace_back(
         std::move(regularPacket),
         sentTime,
         1,
@@ -184,7 +186,8 @@ TEST_P(AckHandlersTest, TestAckMultipleSequentialBlocksLoss) {
         0,
         0,
         LossState(),
-        0));
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
   }
   ReadAckFrame ackFrame;
   ackFrame.largestAcked = 101;
@@ -320,7 +323,7 @@ TEST_P(AckHandlersTest, TestAckBlocksWithGaps) {
     regularPacket.frames.emplace_back(std::move(frame));
     conn.outstandings
         .packetCount[regularPacket.header.getPacketNumberSpace()]++;
-    conn.outstandings.packets.emplace_back(OutstandingPacket(
+    conn.outstandings.packets.emplace_back(
         std::move(regularPacket),
         Clock::now(),
         1,
@@ -331,7 +334,8 @@ TEST_P(AckHandlersTest, TestAckBlocksWithGaps) {
         0,
         0,
         LossState(),
-        0));
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
   }
 
   ReadAckFrame ackFrame;
@@ -430,7 +434,7 @@ TEST_P(AckHandlersTest, TestNonSequentialPacketNumbers) {
     regularPacket.frames.emplace_back(std::move(frame));
     conn.outstandings
         .packetCount[regularPacket.header.getPacketNumberSpace()]++;
-    conn.outstandings.packets.emplace_back(OutstandingPacket(
+    conn.outstandings.packets.emplace_back(
         std::move(regularPacket),
         Clock::now(),
         1,
@@ -441,7 +445,8 @@ TEST_P(AckHandlersTest, TestNonSequentialPacketNumbers) {
         0,
         0,
         LossState(),
-        0));
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
   }
 
   for (PacketNum packetNum = 20; packetNum < 40; packetNum += 3) {
@@ -451,7 +456,7 @@ TEST_P(AckHandlersTest, TestNonSequentialPacketNumbers) {
     regularPacket.frames.emplace_back(std::move(frame));
     conn.outstandings
         .packetCount[regularPacket.header.getPacketNumberSpace()]++;
-    conn.outstandings.packets.emplace_back(OutstandingPacket(
+    conn.outstandings.packets.emplace_back(
         std::move(regularPacket),
         Clock::now(),
         1,
@@ -462,7 +467,8 @@ TEST_P(AckHandlersTest, TestNonSequentialPacketNumbers) {
         0,
         0,
         LossState(),
-        0));
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
   }
 
   ReadAckFrame ackFrame;
@@ -543,7 +549,7 @@ TEST_P(AckHandlersTest, AckVisitorForAckTest) {
   conn.ackStates.appDataAckState.acks.insert(500, 700);
   firstPacket.frames.emplace_back(std::move(firstAckFrame));
   conn.outstandings.packetCount[firstPacket.header.getPacketNumberSpace()]++;
-  conn.outstandings.packets.emplace_back(OutstandingPacket(
+  conn.outstandings.packets.emplace_back(
       std::move(firstPacket),
       Clock::now(),
       0,
@@ -554,7 +560,8 @@ TEST_P(AckHandlersTest, AckVisitorForAckTest) {
       0,
       0,
       LossState(),
-      0));
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   auto secondPacket = createNewPacket(101 /* packetNum */, GetParam());
   WriteAckFrame secondAckFrame;
@@ -564,7 +571,7 @@ TEST_P(AckHandlersTest, AckVisitorForAckTest) {
   conn.ackStates.appDataAckState.acks.insert(1002, 1090);
   secondPacket.frames.emplace_back(std::move(secondAckFrame));
   conn.outstandings.packetCount[secondPacket.header.getPacketNumberSpace()]++;
-  conn.outstandings.packets.emplace_back(OutstandingPacket(
+  conn.outstandings.packets.emplace_back(
       std::move(secondPacket),
       Clock::now(),
       0,
@@ -575,7 +582,8 @@ TEST_P(AckHandlersTest, AckVisitorForAckTest) {
       0,
       0,
       LossState(),
-      0));
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   ReadAckFrame firstReceivedAck;
   firstReceivedAck.largestAcked = 100;
@@ -636,7 +644,7 @@ TEST_P(AckHandlersTest, NoNewAckedPacket) {
   PacketNum packetAfterRtoNum = 10;
   auto packetAfterRto = createNewPacket(packetAfterRtoNum, GetParam());
   conn.outstandings.packetCount[packetAfterRto.header.getPacketNumberSpace()]++;
-  conn.outstandings.packets.emplace_back(OutstandingPacket(
+  conn.outstandings.packets.emplace_back(
       std::move(packetAfterRto),
       Clock::now(),
       0,
@@ -647,7 +655,8 @@ TEST_P(AckHandlersTest, NoNewAckedPacket) {
       0,
       0,
       LossState(),
-      0));
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   ReadAckFrame ackFrame;
   ackFrame.largestAcked = 5;
@@ -704,7 +713,8 @@ TEST_P(AckHandlersTest, AckPacketNumDoesNotExist) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   PacketNum packetNum2 = 10;
   auto regularPacket2 = createNewPacket(packetNum2, GetParam());
@@ -720,7 +730,8 @@ TEST_P(AckHandlersTest, AckPacketNumDoesNotExist) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   // Ack a packet one higher than the packet so that we don't trigger reordering
   // threshold.
@@ -761,7 +772,8 @@ TEST_P(AckHandlersTest, TestHandshakeCounterUpdate) {
         0,
         0,
         LossState(),
-        0);
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
   }
 
   ReadAckFrame ackFrame;
@@ -845,7 +857,7 @@ TEST_P(AckHandlersTest, NoSkipAckVisitor) {
   WriteStreamFrame frame(0, 0, 0, true);
   regularPacket.frames.emplace_back(std::move(frame));
   conn.outstandings.packetCount[regularPacket.header.getPacketNumberSpace()]++;
-  conn.outstandings.packets.emplace_back(OutstandingPacket(
+  conn.outstandings.packets.emplace_back(
       std::move(regularPacket),
       Clock::now(),
       1,
@@ -856,7 +868,8 @@ TEST_P(AckHandlersTest, NoSkipAckVisitor) {
       0,
       0,
       LossState(),
-      0));
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   ReadAckFrame ackFrame;
   ackFrame.largestAcked = 0;
   ackFrame.ackBlocks.emplace_back(0, 0);
@@ -914,7 +927,8 @@ TEST_P(AckHandlersTest, SkipAckVisitor) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   // Give this outstandingPacket an associatedEvent that's not in
   // outstandings.packetEvents
   outstandingPacket.associatedEvent.emplace(GetParam(), 0);
@@ -965,7 +979,8 @@ TEST_P(AckHandlersTest, NoDoubleProcess) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   outstandingPacket1.associatedEvent.emplace(GetParam(), packetNum1);
 
   OutstandingPacket outstandingPacket2(
@@ -979,7 +994,8 @@ TEST_P(AckHandlersTest, NoDoubleProcess) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   // The seconds packet has the same PacketEvent
   outstandingPacket2.associatedEvent.emplace(GetParam(), packetNum1);
 
@@ -1045,7 +1061,8 @@ TEST_P(AckHandlersTest, ClonedPacketsCounter) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   outstandingPacket1.associatedEvent.emplace(GetParam(), packetNum1);
 
   conn.ackStates.appDataAckState.nextPacketNum++;
@@ -1063,7 +1080,8 @@ TEST_P(AckHandlersTest, ClonedPacketsCounter) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   conn.outstandings
       .packetCount[outstandingPacket1.packet.header.getPacketNumberSpace()]++;
@@ -1105,7 +1123,7 @@ TEST_P(AckHandlersTest, UpdateMaxAckDelay) {
   auto regularPacket = createNewPacket(packetNum, GetParam());
   auto sentTime = Clock::now();
   conn.outstandings.packetCount[regularPacket.header.getPacketNumberSpace()]++;
-  conn.outstandings.packets.emplace_back(OutstandingPacket(
+  conn.outstandings.packets.emplace_back(
       std::move(regularPacket),
       sentTime,
       1,
@@ -1116,7 +1134,8 @@ TEST_P(AckHandlersTest, UpdateMaxAckDelay) {
       0,
       0,
       LossState(),
-      0));
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   ReadAckFrame ackFrame;
   // ackDelay has no effect on mrtt
@@ -1186,7 +1205,8 @@ TEST_P(AckHandlersTest, AckNotOutstandingButLoss) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   conn.outstandings.packets.push_back(std::move(outstandingPacket));
   conn.outstandings.packetCount[GetParam()]++;
 
@@ -1227,7 +1247,7 @@ TEST_P(AckHandlersTest, UpdatePendingAckStates) {
   auto regularPacket = createNewPacket(packetNum, GetParam());
   auto sentTime = Clock::now() - 1500ms;
   conn.outstandings.packetCount[regularPacket.header.getPacketNumberSpace()]++;
-  conn.outstandings.packets.emplace_back(OutstandingPacket(
+  conn.outstandings.packets.emplace_back(
       std::move(regularPacket),
       sentTime,
       111,
@@ -1238,7 +1258,8 @@ TEST_P(AckHandlersTest, UpdatePendingAckStates) {
       0,
       0,
       LossState(),
-      0));
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   conn.lossState.totalBytesSent += 111;
   conn.lossState.totalBodyBytesSent += 100;
 
@@ -1384,7 +1405,8 @@ TEST_P(AckHandlersTest, ImplictAckEventCreation) {
         packetNum + 1,
         0,
         LossState(),
-        0);
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
     sentPacket.isAppLimited = (packetNum % 2);
     conn.outstandings.packets.emplace_back(sentPacket);
     packetNum++;
@@ -1456,7 +1478,8 @@ TEST_P(AckHandlersTest, TestRTTPacketObserverCallback) {
         packetNum + 1,
         0,
         LossState(),
-        0);
+        0,
+        OutstandingPacketMetadata::DetailsPerStream());
     sentPacket.isAppLimited = false;
     conn.outstandings.packets.emplace_back(sentPacket);
     packetNum++;
@@ -1729,7 +1752,7 @@ TEST_P(AckHandlersTest, SubMicrosecondRTT) {
   auto packetSendTime = Clock::now();
   auto packet = createNewPacket(5, GetParam());
   conn.outstandings.packetCount[packet.header.getPacketNumberSpace()]++;
-  conn.outstandings.packets.emplace_back(OutstandingPacket(
+  conn.outstandings.packets.emplace_back(
       std::move(packet),
       packetSendTime,
       0,
@@ -1740,7 +1763,8 @@ TEST_P(AckHandlersTest, SubMicrosecondRTT) {
       0,
       0,
       LossState(),
-      0));
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   ReadAckFrame ackFrame;
   auto ackReceiveTime = packetSendTime + 400ns;
diff --git a/quic/state/test/QuicStateFunctionsTest.cpp b/quic/state/test/QuicStateFunctionsTest.cpp
index f125a1cbc..1642e342d 100644
--- a/quic/state/test/QuicStateFunctionsTest.cpp
+++ b/quic/state/test/QuicStateFunctionsTest.cpp
@@ -8,6 +8,7 @@
 
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
+#include "quic/state/OutstandingPacket.h"
 
 #include <quic/common/test/TestUtils.h>
 #include <quic/fizz/server/handshake/FizzServerQuicHandshakeContext.h>
@@ -705,7 +706,8 @@ TEST_F(QuicStateFunctionsTest, GetOutstandingPackets) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   conn.outstandings.packets.emplace_back(
       makeTestLongPacket(LongHeader::Types::Handshake),
       Clock::now(),
@@ -717,7 +719,8 @@ TEST_F(QuicStateFunctionsTest, GetOutstandingPackets) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   conn.outstandings.packets.emplace_back(
       makeTestShortPacket(),
       Clock::now(),
@@ -729,7 +732,8 @@ TEST_F(QuicStateFunctionsTest, GetOutstandingPackets) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   conn.outstandings.packets.emplace_back(
       makeTestLongPacket(LongHeader::Types::Initial),
       Clock::now(),
@@ -741,7 +745,8 @@ TEST_F(QuicStateFunctionsTest, GetOutstandingPackets) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   conn.outstandings.packets.emplace_back(
       makeTestShortPacket(),
       Clock::now(),
@@ -753,7 +758,8 @@ TEST_F(QuicStateFunctionsTest, GetOutstandingPackets) {
       0,
       0,
       LossState(),
-      0);
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   EXPECT_EQ(
       135,
       getFirstOutstandingPacket(conn, PacketNumberSpace::Initial)
diff --git a/quic/state/test/StateDataTest.cpp b/quic/state/test/StateDataTest.cpp
index 179b0e9e0..c373ba2fa 100644
--- a/quic/state/test/StateDataTest.cpp
+++ b/quic/state/test/StateDataTest.cpp
@@ -37,7 +37,18 @@ TEST_F(StateDataTest, SingleLostPacketEvent) {
       100,
       kVersion));
   OutstandingPacket outstandingPacket(
-      packet, Clock::now(), 1234, 0, false, 1234, 0, 0, 0, LossState(), 0);
+      packet,
+      Clock::now(),
+      1234,
+      0,
+      false,
+      1234,
+      0,
+      0,
+      0,
+      LossState(),
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
   CongestionController::LossEvent loss;
   loss.addLostPacket(outstandingPacket);
   EXPECT_EQ(1234, loss.lostBytes);
@@ -52,7 +63,18 @@ TEST_F(StateDataTest, MultipleLostPacketsEvent) {
       100,
       kVersion));
   OutstandingPacket outstandingPacket1(
-      packet1, Clock::now(), 1234, 0, false, 1234, 0, 0, 0, LossState(), 0);
+      packet1,
+      Clock::now(),
+      1234,
+      0,
+      false,
+      1234,
+      0,
+      0,
+      0,
+      LossState(),
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   RegularQuicWritePacket packet2(LongHeader(
       LongHeader::Types::Initial,
@@ -61,7 +83,18 @@ TEST_F(StateDataTest, MultipleLostPacketsEvent) {
       110,
       kVersion));
   OutstandingPacket outstandingPacket2(
-      packet2, Clock::now(), 1357, 0, false, 1357, 0, 0, 0, LossState(), 0);
+      packet2,
+      Clock::now(),
+      1357,
+      0,
+      false,
+      1357,
+      0,
+      0,
+      0,
+      LossState(),
+      0,
+      OutstandingPacketMetadata::DetailsPerStream());
 
   CongestionController::LossEvent loss;
   loss.addLostPacket(outstandingPacket1);