[fix][cpp-client] Pass seek error to callback when SEEK command fails (#549)

diff --git a/.github/workflows/ci-pr-validation.yaml b/.github/workflows/ci-pr-validation.yaml
index 21c9a16..fb5f539 100644
--- a/.github/workflows/ci-pr-validation.yaml
+++ b/.github/workflows/ci-pr-validation.yaml

@@ -99,10 +99,25 @@
           key: vcpkg-${{ runner.os }}-${{ hashFiles('vcpkg.json') }}
           restore-keys: vcpkg-${{ runner.os }}-
 
+      - name: Restore vcpkg downloads cache
+        uses: actions/cache@v4
+        with:
+          path: vcpkg/downloads
+          key: vcpkg-downloads-${{ runner.os }}-${{ hashFiles('vcpkg.json') }}
+          restore-keys: vcpkg-downloads-${{ runner.os }}-
+
       - name: Build the project
         run: |
-          cmake -B build -DINTEGRATE_VCPKG=ON -DBUILD_TESTS=ON -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
-          cmake --build build -j8
+          for attempt in 1 2 3; do
+            echo "Build attempt $attempt/3"
+            if cmake -B build -DINTEGRATE_VCPKG=ON -DBUILD_TESTS=ON -DCMAKE_EXPORT_COMPILE_COMMANDS=ON && cmake --build build -j8; then
+              exit 0
+            fi
+            echo "Attempt $attempt failed (e.g. vcpkg download 502), retrying in 90s..."
+            sleep 90
+          done
+          echo "All build attempts failed"
+          exit 1
 
       - name: Tidy check
         run: |
@@ -137,10 +152,25 @@
           key: vcpkg-${{ runner.os }}-${{ hashFiles('vcpkg.json') }}
           restore-keys: vcpkg-${{ runner.os }}-
 
+      - name: Restore vcpkg downloads cache
+        uses: actions/cache@v4
+        with:
+          path: vcpkg/downloads
+          key: vcpkg-downloads-${{ runner.os }}-${{ hashFiles('vcpkg.json') }}
+          restore-keys: vcpkg-downloads-${{ runner.os }}-
+
       - name: Build core libraries
         run: |
-          cmake -B build -DINTEGRATE_VCPKG=ON -DBUILD_TESTS=OFF
-          cmake --build build -j8
+          for attempt in 1 2 3; do
+            echo "Build attempt $attempt/3"
+            if cmake -B build -DINTEGRATE_VCPKG=ON -DBUILD_TESTS=OFF && cmake --build build -j8; then
+              exit 0
+            fi
+            echo "Attempt $attempt failed (e.g. vcpkg download 502), retrying in 90s..."
+            sleep 90
+          done
+          echo "All build attempts failed"
+          exit 1
 
       - name: Check formatting
         run: |
@@ -164,8 +194,16 @@
 
       - name: Build with Boost.Asio
         run: |
-          cmake -B build-boost-asio -DINTEGRATE_VCPKG=ON -DBUILD_TESTS=ON
-          cmake --build build-boost-asio -j8
+          for attempt in 1 2 3; do
+            echo "Build Boost.Asio attempt $attempt/3"
+            if cmake -B build-boost-asio -DINTEGRATE_VCPKG=ON -DBUILD_TESTS=ON && cmake --build build-boost-asio -j8; then
+              exit 0
+            fi
+            echo "Attempt $attempt failed (e.g. vcpkg download 502), retrying in 90s..."
+            sleep 90
+          done
+          echo "All build attempts failed"
+          exit 1
 
       - name: Build perf tools
         run: |

diff --git a/lib/ConsumerImpl.cc b/lib/ConsumerImpl.cc
index 4a62452..d268484 100644
--- a/lib/ConsumerImpl.cc
+++ b/lib/ConsumerImpl.cc

@@ -1835,7 +1835,9 @@
             if (result == ResultOk) {
                 LockGuard lock(mutex_);
                 if (getCnx().expired() || reconnectionPending_) {
-                    // It's during reconnection, complete the seek future after connection is established
+                    // Reconnection path: delay the seek callback until connectionOpened. clearReceiveQueue()
+                    // and handleCreateConsumer() (which clears incomingMessages_ under the lock) run before
+                    // the seek callback is invoked, so hasMessageAvailable() after seek sees cleared state.
                     seekStatus_ = SeekStatus::COMPLETED;
                     LOG_INFO(getName() << "Delay the seek future until the reconnection is done");
                 } else {
@@ -1860,9 +1862,8 @@
                 LockGuard lock{mutex_};
                 seekStatus_ = SeekStatus::NOT_STARTED;
                 lastSeekArg_ = previousLastSeekArg;
-                executor_->postWork([self, callback{std::exchange(seekCallback_, std::nullopt).value()}]() {
-                    callback(ResultOk);
-                });
+                executor_->postWork([self, callback{std::exchange(seekCallback_, std::nullopt).value()},
+                                     result]() { callback(result); });
             }
         });
 }

diff --git a/tests/ConsumerSeekTest.cc b/tests/ConsumerSeekTest.cc
index f66c27d..d208fc6 100644
--- a/tests/ConsumerSeekTest.cc
+++ b/tests/ConsumerSeekTest.cc

@@ -258,6 +258,31 @@
     client.close();
 }
 
+TEST_F(ConsumerSeekTest, testSeekFailureIsPropagated) {
+    using namespace std::chrono_literals;
+
+    Client client(lookupUrl, ClientConfiguration().setOperationTimeoutSeconds(1));
+    Consumer consumer;
+    ASSERT_EQ(ResultOk, client.subscribe("testSeekFailureIsPropagated", "sub", consumer));
+
+    auto connection = *PulsarFriend::getConnections(client).begin();
+    auto mockServer = std::make_shared<MockServer>(connection);
+    connection->attachMockServer(mockServer);
+    mockServer->setRequestDelay({{"SEEK", 5000}});
+
+    std::promise<Result> promise;
+    auto future = promise.get_future();
+    consumer.seekAsync(MessageId::earliest(), [&promise](Result result) { promise.set_value(result); });
+
+    // Cancel the mocked SEEK success so request completes with timeout.
+    ASSERT_GE(mockServer->close(), 1);
+
+    ASSERT_EQ(future.wait_for(5s), std::future_status::ready);
+    ASSERT_EQ(future.get(), ResultTimeout);
+
+    client.close();
+}
+
 INSTANTIATE_TEST_SUITE_P(Pulsar, ConsumerSeekTest, ::testing::Values(true, false));
 
 }  // namespace pulsar