diff --git a/sdk/api/handlers/handlers_stream.go b/sdk/api/handlers/handlers_stream.go
index 6f0bfbc931b..ee69f89378b 100644
--- a/sdk/api/handlers/handlers_stream.go
+++ b/sdk/api/handlers/handlers_stream.go
@@ -488,17 +488,10 @@ func (h *BaseAPIHandler) executeStreamWithAuthManagerFormats(ctx context.Context
 	var bootstrapErr *interfaces.ErrorMessage
 	readInitialStreamChunks := func() {
 		for {
-			var chunk coreexecutor.StreamChunk
-			var ok bool
-			if ctx != nil {
-				select {
-				case <-ctx.Done():
-					streamCanceledBeforeRead = true
-					return
-				case chunk, ok = <-chunks:
-				}
-			} else {
-				chunk, ok = <-chunks
+			chunk, ok, canceled := nextStreamChunk(ctx, nil, nil, chunks)
+			if canceled {
+				streamCanceledBeforeRead = true
+				return
 			}
 			if !ok {
 				streamClosedBeforeRead = true
diff --git a/sdk/api/handlers/model_execution_delivery_test.go b/sdk/api/handlers/model_execution_delivery_test.go
index 4724a06f572..252a6bc5119 100644
--- a/sdk/api/handlers/model_execution_delivery_test.go
+++ b/sdk/api/handlers/model_execution_delivery_test.go
@@ -3,11 +3,13 @@ package handlers
 import (
 	"context"
 	"testing"
+	"time"
 
 	coreauth "github.com/router-for-me/CLIProxyAPI/v8/sdk/cliproxy/auth"
 	coreexecutor "github.com/router-for-me/CLIProxyAPI/v8/sdk/cliproxy/executor"
 	"github.com/router-for-me/CLIProxyAPI/v8/sdk/cliproxy/usage"
 	sdkconfig "github.com/router-for-me/CLIProxyAPI/v8/sdk/config"
+	"github.com/router-for-me/CLIProxyAPI/v8/sdk/pluginapi"
 )
 
 func TestInternalModelExecutionIsolatesDelivery(t *testing.T) {
@@ -65,3 +67,43 @@ func TestInternalModelExecutionIsolatesDelivery(t *testing.T) {
 		})
 	}
 }
+
+// An internal stream canceled before the handler has its first chunk: the auth manager's forwarder stops on the cancellation and
+// closes its channel, so the close and the cancellation can be ready together at the handler's first read. Without delivery tracking
+// nothing corrects the outcome later, so that read must report the cancellation.
+func TestExecuteModelStreamCanceledBeforeFirstChunkCompletesAsCanceled(t *testing.T) {
+	model := "nested-cancel-first-read-model"
+	var cancel context.CancelFunc
+	executor := &modelExecutionCaptureExecutor{
+		stream: func(context.Context, *coreauth.Auth, coreexecutor.Request, coreexecutor.Options) (*coreexecutor.StreamResult, error) {
+			cancel()
+			chunks := make(chan coreexecutor.StreamChunk, 1)
+			chunks <- coreexecutor.StreamChunk{Payload: []byte("data: {\"ok\":true}\n\n")}
+			close(chunks)
+			return &coreexecutor.StreamResult{Chunks: chunks}, nil
+		},
+	}
+	h := newModelExecutionHandler(t, model, executor, &sdkconfig.SDKConfig{})
+	completions := make(chan pluginapi.RequestCompletion, 1)
+	h.SetPluginHost(&handlerInterceptorTestHost{completeRequest: func(_ context.Context, completion pluginapi.RequestCompletion) {
+		completions <- completion
+	}})
+	for round := range 2000 {
+		ctx, roundCancel := context.WithCancel(context.Background())
+		cancel = roundCancel
+		result, errMsg := h.ExecuteModelStream(ctx, ModelExecutionRequest{Model: model, EntryProtocol: "openai", Stream: true, Body: []byte(`{"model":"` + model + `"}`)})
+		if errMsg == nil {
+			for range result.Chunks {
+			}
+		}
+		roundCancel()
+		select {
+		case completion := <-completions:
+			if completion.Outcome != pluginapi.RequestCompletionCanceled {
+				t.Fatalf("round %d: completion = %+v, want a cancellation", round, completion)
+			}
+		case <-time.After(5 * time.Second):
+			t.Fatal("missing lifecycle completion")
+		}
+	}
+}