grpc
diff --git a/api/src/main/java/io/grpc/ClientStreamTracer.java b/api/src/main/java/io/grpc/ClientStreamTracer.java
@@ -99,6 +99,15 @@ public void inboundTrailers(Metadata trailers) {
   public void addOptionalLabel(String key, String value) {
   }
 
+  /**
+   * The stream was cancelled from the client side before a normal response was received.
+   *
+   * @param status the cancellation status
+   * @since 1.84.0
+   */
+  public void cancelled(Status status) {
+  }
+
   /**
    * Factory class for {@link ClientStreamTracer}.
    */

diff --git a/binder/src/androidTest/java/io/grpc/binder/internal/BinderClientTransportTest.java b/binder/src/androidTest/java/io/grpc/binder/internal/BinderClientTransportTest.java
@@ -292,6 +292,22 @@ public void testMessageProducerClosedAfterStream_b169313545() throws Exception {
     streamListener.drainMessages();
   }
 
+  @Test
+  public void testCancelStream_notifiesTracer() throws Exception {
+    transport = new BinderClientTransportBuilder().build();
+    startAndAwaitReady(transport, transportListener);
+
+    ClientStreamTracer mockTracer = org.mockito.Mockito.mock(ClientStreamTracer.class);
+    ClientStream stream =
+        transport.newStream(methodDesc, new Metadata(), CallOptions.DEFAULT, new ClientStreamTracer[]{mockTracer});
+
+    stream.start(streamListener);
+    Status cancelStatus = Status.CANCELLED.withDescription("Client cancelled");
+    stream.cancel(cancelStatus);
+
+    org.mockito.Mockito.verify(mockTracer, org.mockito.Mockito.timeout(5000)).cancelled(org.mockito.ArgumentMatchers.eq(cancelStatus));
+  }
+
   @Test
   public void testNewStreamBeforeTransportReadyFails() throws Exception {
     // Use a special SecurityPolicy that lets us act before the transport is setup/ready.

diff --git a/binder/src/main/java/io/grpc/binder/internal/Inbound.java b/binder/src/main/java/io/grpc/binder/internal/Inbound.java
@@ -268,6 +268,9 @@ private final void deliverInternal() {
 
   @GuardedBy("this")
   final void closeOnCancel(Status status) {
+    if (!isClosed() && statsTraceContext != null) {
+      statsTraceContext.clientCancelled(status);
+    }
     closeAbnormal(Status.CANCELLED, status, false);
   }
 

diff --git a/core/src/main/java/io/grpc/internal/AbstractClientStream.java b/core/src/main/java/io/grpc/internal/AbstractClientStream.java
@@ -251,6 +251,8 @@ protected TransportState(
       }
     }
 
+
+
     private void setFullStreamDecompression(boolean fullStreamDecompression) {
       this.fullStreamDecompression = fullStreamDecompression;
     }
@@ -391,16 +393,16 @@ protected void inboundTrailersReceived(Metadata trailers, Status status) {
      * method must be called from the transport thread.
      *
      * @param status the new status to set
-     * @param stopDelivery if {@code true}, interrupts any further delivery of inbound messages that
+     * @param cancelled if {@code true}, interrupts any further delivery of inbound messages that
      *        may already be queued up in the deframer. If {@code false}, the listener will be
      *        notified immediately after all currently completed messages in the deframer have been
      *        delivered to the application.
      * @param trailers new instance of {@code Trailers}, either empty or those returned by the
      *        server
      */
-    public final void transportReportStatus(final Status status, boolean stopDelivery,
+    public final void transportReportStatus(final Status status, boolean cancelled,
         final Metadata trailers) {
-      transportReportStatus(status, RpcProgress.PROCESSED, stopDelivery, trailers);
+      transportReportStatus(status, RpcProgress.PROCESSED, cancelled, trailers);
     }
 
     /**
@@ -411,7 +413,7 @@ public final void transportReportStatus(final Status status, boolean stopDeliver
      * @param rpcProgress RPC progress that the
      *        {@link ClientStreamListener#closed(Status, RpcProgress, Metadata)}
      *        will receive
-     * @param stopDelivery if {@code true}, interrupts any further delivery of inbound messages that
+     * @param cancelled if {@code true}, interrupts any further delivery of inbound messages that
      *        may already be queued up in the deframer and overrides any previously queued status.
      *        If {@code false}, the listener will be notified immediately after all currently
      *        completed messages in the deframer have been delivered to the application.
@@ -421,16 +423,19 @@ public final void transportReportStatus(final Status status, boolean stopDeliver
     public final void transportReportStatus(
         final Status status,
         final RpcProgress rpcProgress,
-        boolean stopDelivery,
+        boolean cancelled,
         final Metadata trailers) {
       checkNotNull(status, "status");
       checkNotNull(trailers, "trailers");
-      // If stopDelivery, we continue in case previous invocation is waiting for stall
-      if (statusReported && !stopDelivery) {
+      // If cancelled, we continue in case previous invocation is waiting for stall
+      if (statusReported && !cancelled) {
         return;
       }
       statusReported = true;
       statusReportedIsOk = status.isOk();
+      if (cancelled) {
+        statsTraceCtx.clientCancelled(status);
+      }
       onStreamDeallocated();
 
       if (deframerClosed) {
@@ -444,7 +449,7 @@ public void run() {
                 closeListener(status, rpcProgress, trailers);
               }
             };
-        closeDeframer(stopDelivery);
+        closeDeframer(cancelled);
       }
     }
 

diff --git a/core/src/main/java/io/grpc/internal/ForwardingClientStreamTracer.java b/core/src/main/java/io/grpc/internal/ForwardingClientStreamTracer.java
@@ -64,6 +64,11 @@ public void addOptionalLabel(String key, String value) {
     delegate().addOptionalLabel(key, value);
   }
 
+  @Override
+  public void cancelled(Status status) {
+    delegate().cancelled(status);
+  }
+
   @Override
   public void streamClosed(Status status) {
     delegate().streamClosed(status);

diff --git a/core/src/main/java/io/grpc/internal/StatsTraceContext.java b/core/src/main/java/io/grpc/internal/StatsTraceContext.java
@@ -167,6 +167,19 @@ public void serverCallMethodResolved(MethodDescriptor<?, ?> method) {
     }
   }
 
+  /**
+   * See {@link ClientStreamTracer#cancelled}. For client-side only.
+   *
+   * <p>Called from abstract stream implementations.
+   */
+  public void clientCancelled(Status status) {
+    for (StreamTracer tracer : tracers) {
+      if (tracer instanceof ClientStreamTracer) {
+        ((ClientStreamTracer) tracer).cancelled(status);
+      }
+    }
+  }
+
   /**
    * See {@link StreamTracer#streamClosed}. This may be called multiple times, and only the first
    * value will be taken.

diff --git a/core/src/test/java/io/grpc/internal/AbstractClientStreamTest.java b/core/src/test/java/io/grpc/internal/AbstractClientStreamTest.java
@@ -39,6 +39,7 @@
 
 import io.grpc.Attributes;
 import io.grpc.CallOptions;
+import io.grpc.ClientStreamTracer;
 import io.grpc.Codec;
 import io.grpc.Deadline;
 import io.grpc.Grpc;
@@ -155,6 +156,139 @@ public void cancel(Status errorStatus) {
     verify(mockListener).closed(any(Status.class), same(PROCESSED), any(Metadata.class));
   }
 
+  @Test
+  public void cancel_notifiesStatsTraceContext() {
+    ClientStreamTracer mockTracer = mock(ClientStreamTracer.class);
+    StatsTraceContext customStatsTraceCtx = new StatsTraceContext(new StreamTracer[] {mockTracer});
+    final BaseTransportState state = new BaseTransportState(customStatsTraceCtx, transportTracer);
+    AbstractClientStream stream = new BaseAbstractClientStream(allocator, state, new BaseSink() {
+      @Override
+      public void cancel(Status errorStatus) {
+        state.transportReportStatus(errorStatus, true, new Metadata());
+      }
+    }, customStatsTraceCtx, transportTracer);
+    stream.start(mockListener);
+
+    Status cancelStatus = Status.CANCELLED.withDescription("Cancelled by test");
+    stream.cancel(cancelStatus);
+
+    verify(mockTracer).cancelled(cancelStatus);
+  }
+
+  @Test
+  public void transportReportStatus_okFirst_lateCancellationDoesNotNotifyTracerCancelled() {
+    ClientStreamTracer mockTracer = mock(ClientStreamTracer.class);
+    StatsTraceContext customStatsTraceCtx = new StatsTraceContext(new StreamTracer[] {mockTracer});
+    final BaseTransportState state = new BaseTransportState(customStatsTraceCtx, transportTracer);
+    AbstractClientStream stream = new BaseAbstractClientStream(allocator, state, new BaseSink() {
+      @Override
+      public void cancel(Status errorStatus) {
+        state.transportReportStatus(errorStatus, true, new Metadata());
+      }
+    }, customStatsTraceCtx, transportTracer);
+    stream.start(mockListener);
+
+    // Report Status.OK first
+    state.transportReportStatus(Status.OK, false, new Metadata());
+
+    // Subsequent late cancellation
+    verify(mockTracer, never()).cancelled(any(Status.class));
+  }
+
+  @Test
+  public void transportReportStatus_stopDeliveryFalse_doesNotNotifyTracerCancelled() {
+    ClientStreamTracer mockTracer = mock(ClientStreamTracer.class);
+    StatsTraceContext customStatsTraceCtx = new StatsTraceContext(new StreamTracer[] {mockTracer});
+    final BaseTransportState state = new BaseTransportState(customStatsTraceCtx, transportTracer);
+    AbstractClientStream stream = new BaseAbstractClientStream(allocator, state, new BaseSink() {},
+        customStatsTraceCtx, transportTracer);
+    stream.start(mockListener);
+
+    // Server-initiated CANCELLED (stopDelivery = false)
+    state.transportReportStatus(Status.CANCELLED, false, new Metadata());
+
+    verify(mockTracer, never()).cancelled(any(Status.class));
+    verify(mockTracer).streamClosed(Status.CANCELLED);
+  }
+
+  @Test
+  public void transportReportStatus_stopDeliveryTrue_notifiesTracerCancelled() {
+    ClientStreamTracer mockTracer = mock(ClientStreamTracer.class);
+    StatsTraceContext customStatsTraceCtx = new StatsTraceContext(new StreamTracer[] {mockTracer});
+    final BaseTransportState state = new BaseTransportState(customStatsTraceCtx, transportTracer);
+    AbstractClientStream stream = new BaseAbstractClientStream(allocator, state, new BaseSink() {},
+        customStatsTraceCtx, transportTracer);
+    stream.start(mockListener);
+
+    // Client/Transport-initiated cancellation (stopDelivery = true)
+    Status cancelStatus = Status.CANCELLED.withDescription("Client cancelled");
+    state.transportReportStatus(cancelStatus, true, new Metadata());
+
+    verify(mockTracer).cancelled(cancelStatus);
+    verify(mockTracer).streamClosed(cancelStatus);
+  }
+
+  @Test
+  public void transportReportStatus_stopDeliveryFalse_deadlineExceeded_noTracerCancelled() {
+    ClientStreamTracer mockTracer = mock(ClientStreamTracer.class);
+    StatsTraceContext customStatsTraceCtx = new StatsTraceContext(new StreamTracer[] {mockTracer});
+    final BaseTransportState state = new BaseTransportState(customStatsTraceCtx, transportTracer);
+    AbstractClientStream stream = new BaseAbstractClientStream(
+        allocator, state, new BaseSink() {}, customStatsTraceCtx, transportTracer);
+    stream.start(mockListener);
+
+    // Server-initiated DEADLINE_EXCEEDED (stopDelivery = false)
+    Status status = Status.DEADLINE_EXCEEDED.withDescription("Server deadline exceeded");
+    state.transportReportStatus(status, false, new Metadata());
+
+    verify(mockTracer, never()).cancelled(any(Status.class));
+    verify(mockTracer).streamClosed(status);
+  }
+
+  @Test
+  public void transportReportStatus_stopDeliveryTrue_deadlineExceeded_notifiesTracerCancelled() {
+    ClientStreamTracer mockTracer = mock(ClientStreamTracer.class);
+    StatsTraceContext customStatsTraceCtx = new StatsTraceContext(new StreamTracer[] {mockTracer});
+    final BaseTransportState state = new BaseTransportState(customStatsTraceCtx, transportTracer);
+    AbstractClientStream stream = new BaseAbstractClientStream(
+        allocator, state, new BaseSink() {}, customStatsTraceCtx, transportTracer);
+    stream.start(mockListener);
+
+    // Client/Transport-initiated deadline exceeded (stopDelivery = true)
+    Status status = Status.DEADLINE_EXCEEDED.withDescription("Client deadline exceeded");
+    state.transportReportStatus(status, true, new Metadata());
+
+    verify(mockTracer).cancelled(status);
+    verify(mockTracer).streamClosed(status);
+  }
+
+  @Test
+  public void closeListener_deferredDeframerClose_stopDeliveryFalse_delaysCloseListener() {
+    ClientStreamTracer mockTracer = mock(ClientStreamTracer.class);
+    StatsTraceContext customStatsTraceCtx = new StatsTraceContext(new StreamTracer[] {mockTracer});
+    BaseTransportState state = new BaseTransportState(customStatsTraceCtx, transportTracer);
+    AbstractClientStream stream = new BaseAbstractClientStream(
+        allocator, state, new BaseSink() {}, customStatsTraceCtx, transportTracer);
+    stream.start(mockListener);
+
+    // Send partial message into deframer
+    byte[] data = new byte[] {0, 0, 0, 0, 2, 1}; // 2-byte frame, only 1 byte delivered
+    state.deframe(ReadableBuffers.wrap(data));
+
+    Status statusFalse = Status.CANCELLED.withDescription("deferred stopDelivery false");
+    state.transportReportStatus(statusFalse, false, new Metadata());
+
+    // Listener is not closed yet because deframer is mid-frame and waiting for complete frame
+    verify(mockTracer, never()).cancelled(any(Status.class));
+    verify(mockTracer, never()).streamClosed(any(Status.class));
+
+    // Request message and provide remaining byte of frame to complete deframer processing
+    stream.request(1);
+    state.deframe(ReadableBuffers.wrap(new byte[] {2}));
+    verify(mockTracer, never()).cancelled(any(Status.class));
+    verify(mockTracer).streamClosed(any(Status.class));
+  }
+
   @Test
   public void startFailsOnNullListener() {
     AbstractClientStream stream =

diff --git a/core/src/test/java/io/grpc/internal/StatsTraceContextTest.java b/core/src/test/java/io/grpc/internal/StatsTraceContextTest.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2026 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.internal;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
+
+import io.grpc.ClientStreamTracer;
+import io.grpc.ServerStreamTracer;
+import io.grpc.Status;
+import io.grpc.StreamTracer;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link StatsTraceContext}. */
+@RunWith(JUnit4.class)
+public class StatsTraceContextTest {
+
+  @Test
+  public void clientCancelled_notifiesClientStreamTracers() {
+    ClientStreamTracer clientTracer = mock(ClientStreamTracer.class);
+    ServerStreamTracer serverTracer = mock(ServerStreamTracer.class);
+
+    StatsTraceContext statsTraceCtx = new StatsTraceContext(
+        new StreamTracer[] {clientTracer, serverTracer});
+
+    Status cancelledStatus = Status.CANCELLED.withDescription("Client cancelled");
+    statsTraceCtx.clientCancelled(cancelledStatus);
+
+    verify(clientTracer).cancelled(cancelledStatus);
+    verifyNoInteractions(serverTracer);
+  }
+}
diff --git a/inprocess/src/main/java/io/grpc/inprocess/InProcessTransport.java b/inprocess/src/main/java/io/grpc/inprocess/InProcessTransport.java
@@ -846,6 +846,7 @@ public void cancel(Status reason) {
         if (!internalCancel(serverStatus, serverStatus)) {
           return;
         }
+        statsTraceCtx.clientCancelled(reason);
         serverStream.clientCancelled(reason);
         streamClosed();
       }