diff --git a/.github/actions/ci/action.yml b/.github/actions/ci/action.yml
index 35c1ca23b..a1e30de49 100644
--- a/.github/actions/ci/action.yml
+++ b/.github/actions/ci/action.yml
@@ -37,6 +37,10 @@ inputs:
     description: 'Whether to install CURL development libraries. Required for OpenTelemetry builds (server-sdk-otel), but does not enable CURL networking for the SDK itself.'
     required: false
     default: 'false'
+  use_redis:
+    description: 'Whether to enable Redis support (LD_BUILD_REDIS_SUPPORT=ON). Leave unset to preserve automatic detection for Redis targets.'
+    required: false
+    default: ''
 
 runs:
   using: composite
@@ -58,7 +62,7 @@ runs:
       id: install-curl
     - name: Build Library
       shell: bash
-      run: ./scripts/build.sh ${{ inputs.cmake_target }} ON ${{ inputs.use_curl }}
+      run: ./scripts/build.sh ${{ inputs.cmake_target }} ON ${{ inputs.use_curl }} ${{ inputs.use_redis }}
       env:
         BOOST_ROOT: ${{ steps.install-boost.outputs.BOOST_ROOT }}
         Boost_DIR: ${{ steps.install-boost.outputs.Boost_DIR }}
@@ -69,7 +73,7 @@ runs:
       id: build-tests
       if: inputs.run_tests == 'true'
       shell: bash
-      run: ./scripts/build.sh gtest_${{ inputs.cmake_target }} ON ${{ inputs.use_curl }}
+      run: ./scripts/build.sh gtest_${{ inputs.cmake_target }} ON ${{ inputs.use_curl }} ${{ inputs.use_redis }}
       env:
         BOOST_ROOT: ${{ steps.install-boost.outputs.BOOST_ROOT }}
         Boost_DIR: ${{ steps.install-boost.outputs.Boost_DIR }}
diff --git a/.github/workflows/server-redis.yml b/.github/workflows/server-redis.yml
index 0a73c4786..0a88a059b 100644
--- a/.github/workflows/server-redis.yml
+++ b/.github/workflows/server-redis.yml
@@ -14,6 +14,61 @@ on:
     - cron: '0 8 * * *'
 
 jobs:
+  contract-tests:
+    runs-on: ubuntu-22.04
+    services:
+      redis:
+        image: redis
+        ports:
+          - 6379:6379
+    env:
+      TEST_SERVICE_PORT: 8123
+      TEST_SERVICE_BINARY: ./build/contract-tests/server-contract-tests/server-tests
+    steps:
+      # https://github.com/actions/checkout/releases/tag/v4.3.0
+      - uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955
+      - uses: ./.github/actions/ci
+        with:
+          cmake_target: server-tests
+          run_tests: false
+          use_redis: true
+      - name: 'Launch test service as background task'
+        run: $TEST_SERVICE_BINARY $TEST_SERVICE_PORT 2>&1 &
+      # https://github.com/launchdarkly/gh-actions/releases/tag/contract-tests-v1.3.0
+      - uses: launchdarkly/gh-actions/actions/contract-tests@5adb11fd6953e1bc35d9cf1fc1b4374c464e3a8b
+        with:
+          test_service_port: ${{ env.TEST_SERVICE_PORT }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+          enable_persistence_tests: true
+
+  contract-tests-curl:
+    runs-on: ubuntu-22.04
+    services:
+      redis:
+        image: redis
+        ports:
+          - 6379:6379
+    env:
+      TEST_SERVICE_PORT: 8123
+      TEST_SERVICE_BINARY: ./build/contract-tests/server-contract-tests/server-tests
+    steps:
+      # https://github.com/actions/checkout/releases/tag/v4.3.0
+      - uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955
+      - uses: ./.github/actions/ci
+        with:
+          cmake_target: server-tests
+          run_tests: false
+          use_curl: true
+          use_redis: true
+      - name: 'Launch test service as background task'
+        run: $TEST_SERVICE_BINARY $TEST_SERVICE_PORT 2>&1 &
+      # https://github.com/launchdarkly/gh-actions/releases/tag/contract-tests-v1.3.0
+      - uses: launchdarkly/gh-actions/actions/contract-tests@5adb11fd6953e1bc35d9cf1fc1b4374c464e3a8b
+        with:
+          test_service_port: ${{ env.TEST_SERVICE_PORT }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+          enable_persistence_tests: true
+
   build-test-redis:
     runs-on: ubuntu-22.04
     services:
@@ -28,6 +83,7 @@ jobs:
         with:
           cmake_target: launchdarkly-cpp-server-redis-source
           simulate_release: true
+          use_redis: true
   build-redis-mac:
     runs-on: macos-15
     steps:
@@ -39,6 +95,7 @@ jobs:
           platform_version: 12
           run_tests: false # TODO: figure out how to run Redis service on Mac
           simulate_release: true
+          use_redis: true
   build-test-redis-windows:
     runs-on: windows-2022
     steps:
@@ -57,3 +114,4 @@ jobs:
           toolset: msvc
           run_tests: false # TODO: figure out how to run Redis service on Windows
           simulate_windows_release: true
+          use_redis: true
diff --git a/contract-tests/data-model/include/data_model/data_model.hpp b/contract-tests/data-model/include/data_model/data_model.hpp
index 679fd0015..d05d8c73f 100644
--- a/contract-tests/data-model/include/data_model/data_model.hpp
+++ b/contract-tests/data-model/include/data_model/data_model.hpp
@@ -150,6 +150,34 @@ struct ConfigWrapper {
 
 NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(ConfigWrapper, name, version);
 
+struct ConfigPersistentCache {
+    std::string mode;  // "off", "ttl", "infinite"
+    std::optional<int> ttl;  // TTL in seconds (sent by test harness as "ttl")
+};
+
+NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(ConfigPersistentCache,
+                                                mode,
+                                                ttl);
+
+struct ConfigPersistentStore {
+    std::string type;  // "redis", "consul", "dynamodb"
+    std::string dsn;
+    std::optional<std::string> prefix;
+};
+
+NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(ConfigPersistentStore,
+                                                type,
+                                                dsn,
+                                                prefix);
+
+struct ConfigPersistentDataStore {
+    ConfigPersistentStore store;
+    ConfigPersistentCache cache;
+};
+
+NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(ConfigPersistentDataStore,
+                                                store,
+                                                cache);
 struct ConfigParams {
     std::string credential;
     std::optional<uint32_t> startWaitTimeMs;
@@ -164,6 +192,7 @@ struct ConfigParams {
     std::optional<ConfigProxyParams> proxy;
     std::optional<ConfigHooksParams> hooks;
     std::optional<ConfigWrapper> wrapper;
+    std::optional<ConfigPersistentDataStore> persistentDataStore;
 };
 
 NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(ConfigParams,
@@ -179,7 +208,8 @@ NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(ConfigParams,
                                                 tls,
                                                 proxy,
                                                 hooks,
-                                                wrapper);
+                                                wrapper,
+                                                persistentDataStore);
 
 struct ContextSingleParams {
     std::optional<std::string> kind;
diff --git a/contract-tests/server-contract-tests/CMakeLists.txt b/contract-tests/server-contract-tests/CMakeLists.txt
index 9455cd27e..faeca51eb 100644
--- a/contract-tests/server-contract-tests/CMakeLists.txt
+++ b/contract-tests/server-contract-tests/CMakeLists.txt
@@ -28,4 +28,9 @@ target_link_libraries(server-tests PRIVATE
         contract-test-data-model
         )
 
+if (LD_BUILD_REDIS_SUPPORT)
+    target_link_libraries(server-tests PRIVATE launchdarkly::server_redis_source)
+    target_compile_definitions(server-tests PRIVATE LD_REDIS_SUPPORT_ENABLED)
+endif ()
+
 target_include_directories(server-tests PUBLIC include)
diff --git a/contract-tests/server-contract-tests/src/entity_manager.cpp b/contract-tests/server-contract-tests/src/entity_manager.cpp
index 085df1c2d..63e095481 100644
--- a/contract-tests/server-contract-tests/src/entity_manager.cpp
+++ b/contract-tests/server-contract-tests/src/entity_manager.cpp
@@ -7,6 +7,10 @@
 
 #include <boost/json.hpp>
 
+#ifdef LD_REDIS_SUPPORT_ENABLED
+#include <launchdarkly/server_side/integrations/redis/redis_source.hpp>
+#endif
+
 using launchdarkly::LogLevel;
 using namespace launchdarkly::server_side;
 
@@ -154,6 +158,56 @@ std::optional<std::string> EntityManager::create(ConfigParams const& in) {
         }
     }
 
+#ifdef LD_REDIS_SUPPORT_ENABLED
+    if (in.persistentDataStore) {
+        if (in.persistentDataStore->store.type == "redis") {
+            std::string prefix =
+                in.persistentDataStore->store.prefix.value_or("launchdarkly");
+
+            auto redis_result = launchdarkly::server_side::integrations::
+                RedisDataSource::Create(in.persistentDataStore->store.dsn,
+                                        prefix);
+
+            if (!redis_result) {
+                LD_LOG(logger_, LogLevel::kWarn)
+                    << "entity_manager: couldn't create Redis data source: "
+                    << redis_result.error();
+                return std::nullopt;
+            }
+
+            auto lazy_load = config::builders::LazyLoadBuilder();
+            lazy_load.Source(std::move(*redis_result));
+
+            // Configure cache mode
+            // Default is 5 minutes, but contract tests may specify:
+            // - "off": disable caching (fetch from DB every time)
+            // - "ttl": custom TTL in seconds (test harness sends seconds)
+            // - "infinite": never expire cached items
+            if (in.persistentDataStore->cache.mode == "off") {
+                lazy_load.CacheRefresh(std::chrono::seconds(0));
+            } else if (in.persistentDataStore->cache.mode == "ttl") {
+                if (in.persistentDataStore->cache.ttl) {
+                    lazy_load.CacheRefresh(std::chrono::seconds(
+                        *in.persistentDataStore->cache.ttl));
+                }
+            } else if (in.persistentDataStore->cache.mode == "infinite") {
+                // Use a very large TTL to effectively never expire
+                lazy_load.CacheRefresh(std::chrono::hours(24 * 365));
+            }
+            // If no mode specified, the default 5-minute TTL is used
+
+            config_builder.DataSystem().Method(
+                config::builders::DataSystemBuilder::LazyLoad(
+                    std::move(lazy_load)));
+        } else {
+            LD_LOG(logger_, LogLevel::kWarn)
+                << "entity_manager: unsupported persistent store type: "
+                << in.persistentDataStore->store.type;
+            return std::nullopt;
+        }
+    }
+#endif
+
     auto config = config_builder.Build();
     if (!config) {
         LD_LOG(logger_, LogLevel::kWarn)
diff --git a/contract-tests/server-contract-tests/src/main.cpp b/contract-tests/server-contract-tests/src/main.cpp
index e017a8634..481997961 100644
--- a/contract-tests/server-contract-tests/src/main.cpp
+++ b/contract-tests/server-contract-tests/src/main.cpp
@@ -51,6 +51,9 @@ int main(int argc, char* argv[]) {
         srv.add_capability("evaluation-hooks");
         srv.add_capability("track-hooks");
         srv.add_capability("wrapper");
+#ifdef LD_REDIS_SUPPORT_ENABLED
+        srv.add_capability("persistent-data-store-redis");
+#endif
 
         net::signal_set signals{ioc, SIGINT, SIGTERM};
 
diff --git a/libs/server-sdk/src/client_impl.cpp b/libs/server-sdk/src/client_impl.cpp
index 0c53440d7..64d9f17b3 100644
--- a/libs/server-sdk/src/client_impl.cpp
+++ b/libs/server-sdk/src/client_impl.cpp
@@ -186,11 +186,19 @@ AllFlagsState ClientImpl::AllFlagsState(Context const& context,
     std::unordered_map<Client::FlagKey, Value> result;
 
     if (!Initialized()) {
-        LD_LOG(logger_, LogLevel::kWarn)
-            << "AllFlagsState() called before client has finished "
-               "initializing. Data source not available. Returning empty state";
+        if (data_system_->CanEvaluateWhenNotInitialized()) {
+            LD_LOG(logger_, LogLevel::kWarn)
+                << "AllFlagsState() called before LaunchDarkly client "
+                   "initialization completed; using last known values "
+                   "from data store";
+        } else {
+            LD_LOG(logger_, LogLevel::kWarn)
+                << "AllFlagsState() called before client has finished "
+                   "initializing. Data source not available. Returning "
+                   "empty state";
 
-        return {};
+            return {};
+        }
     }
 
     AllFlagsStateBuilder builder{options};
@@ -418,7 +426,16 @@ EvaluationDetail<Value> ClientImpl::VariationInternal(
 std::optional<enum EvaluationReason::ErrorKind> ClientImpl::PreEvaluationChecks(
     Context const& context) const {
     if (!Initialized()) {
-        return EvaluationReason::ErrorKind::kClientNotReady;
+        if (data_system_->CanEvaluateWhenNotInitialized()) {
+            LD_LOG(logger_, LogLevel::kWarn)
+                << "Evaluation called before LaunchDarkly client "
+                   "initialization completed; using last known values "
+                   "from data store. The $inited key was not found in "
+                   "the store; typically a Relay Proxy or other SDK "
+                   "should set this key.";
+        } else {
+            return EvaluationReason::ErrorKind::kClientNotReady;
+        }
     }
     if (!context.Valid()) {
         return EvaluationReason::ErrorKind::kUserNotSpecified;
diff --git a/libs/server-sdk/src/data_interfaces/system/idata_system.hpp b/libs/server-sdk/src/data_interfaces/system/idata_system.hpp
index 0edf778db..73b1eefef 100644
--- a/libs/server-sdk/src/data_interfaces/system/idata_system.hpp
+++ b/libs/server-sdk/src/data_interfaces/system/idata_system.hpp
@@ -21,6 +21,22 @@ class IDataSystem : public IStore {
      */
     virtual void Initialize() = 0;
 
+    /**
+     * @brief Returns true if the data system is capable of serving
+     * flag evaluations even when Initialized() returns false.
+     *
+     * This is the case for Lazy Load (daemon mode), where data can be
+     * fetched on-demand from the persistent store regardless of whether
+     * the $inited key has been set. In contrast, Background Sync
+     * cannot serve evaluations until initial data is received.
+     *
+     * When this returns true, the evaluation path should log a warning
+     * (rather than returning CLIENT_NOT_READY) if Initialized() is false.
+     */
+    [[nodiscard]] virtual bool CanEvaluateWhenNotInitialized() const {
+        return false;
+    }
+
     virtual ~IDataSystem() override = default;
     IDataSystem(IDataSystem const& item) = delete;
     IDataSystem(IDataSystem&& item) = delete;
diff --git a/libs/server-sdk/src/data_systems/lazy_load/lazy_load_system.hpp b/libs/server-sdk/src/data_systems/lazy_load/lazy_load_system.hpp
index 9584f60d6..f1730fafa 100644
--- a/libs/server-sdk/src/data_systems/lazy_load/lazy_load_system.hpp
+++ b/libs/server-sdk/src/data_systems/lazy_load/lazy_load_system.hpp
@@ -58,6 +58,10 @@ class LazyLoad final : public data_interfaces::IDataSystem {
 
     bool Initialized() const override;
 
+    [[nodiscard]] bool CanEvaluateWhenNotInitialized() const override {
+        return true;
+    }
+
     // Public for usage in tests.
     struct Kinds {
         static integrations::FlagKind const Flag;
diff --git a/libs/server-sdk/tests/lazy_load_system_test.cpp b/libs/server-sdk/tests/lazy_load_system_test.cpp
index f908a8ac8..c2b99bd45 100644
--- a/libs/server-sdk/tests/lazy_load_system_test.cpp
+++ b/libs/server-sdk/tests/lazy_load_system_test.cpp
@@ -338,3 +338,15 @@ TEST_F(LazyLoadTest, InitializeCalledAgainAfterTTL) {
         ASSERT_TRUE(lazy_load.Initialized());
     }
 }
+
+TEST_F(LazyLoadTest, CanEvaluateWhenNotInitialized) {
+    built::LazyLoadConfig const config{
+        built::LazyLoadConfig::EvictionPolicy::Disabled,
+        std::chrono::seconds(10), mock_reader};
+
+    data_systems::LazyLoad const lazy_load(logger, config, status_manager);
+
+    // LazyLoad can always serve evaluations on demand, even if not
+    // initialized (i.e. $inited key not found in store).
+    ASSERT_TRUE(lazy_load.CanEvaluateWhenNotInitialized());
+}
diff --git a/scripts/build.sh b/scripts/build.sh
index 7fd27a47e..f766f0583 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -7,6 +7,7 @@
 # $1 the name of the target. For example "launchdarkly-cpp-common".
 # $2 ON/OFF which enables/disables building in a test configuration (unit tests + contract tests.)
 # $3 (optional) true/false to enable/disable CURL networking (LD_CURL_NETWORKING)
+# $4 (optional) true/false to enable/disable Redis support (LD_BUILD_REDIS_SUPPORT)
 
 function cleanup {
   cd ..
@@ -31,6 +32,13 @@ if [ "$3" == "true" ]; then
   build_curl="ON"
 fi
 
+# Check for Redis support option (override the automatic detection if explicitly passed)
+if [ "$4" == "true" ]; then
+  build_redis="ON"
+elif [ "$4" == "false" ]; then
+  build_redis="OFF"
+fi
+
 # Set build type to Debug when testing is enabled
 build_type="Release"
 if [ "$2" == "ON" ]; then