diff --git a/ai-service/tests/test_mode_router.py b/ai-service/tests/test_mode_router.py
new file mode 100644
index 0000000..f54da75
--- /dev/null
+++ b/ai-service/tests/test_mode_router.py
@@ -0,0 +1,297 @@
+"""
+Unit tests for Mode Router.
+[AC-AISVC-RES-09,10,11,12,13,14] Tests for mode routing, complexity analysis, and fallback.
+"""
+
+import pytest
+from unittest.mock import AsyncMock, MagicMock, patch
+
+from app.services.retrieval.routing_config import (
+    RagRuntimeMode,
+    RoutingConfig,
+    StrategyContext,
+)
+from app.services.retrieval.mode_router import (
+    ComplexityAnalyzer,
+    ModeRouteResult,
+    ModeRouter,
+    get_mode_router,
+    reset_mode_router,
+)
+
+
+class TestComplexityAnalyzer:
+    """[AC-AISVC-RES-12,13] Tests for ComplexityAnalyzer."""
+
+    @pytest.fixture
+    def analyzer(self):
+        return ComplexityAnalyzer()
+
+    def test_analyze_empty_query(self, analyzer):
+        """Empty query should have zero complexity."""
+        score = analyzer.analyze("")
+
+        assert score == 0.0
+
+    def test_analyze_short_query(self, analyzer):
+        """Short query should have low complexity."""
+        score = analyzer.analyze("简单问题")
+
+        assert score < 0.3
+
+    def test_analyze_long_query(self, analyzer):
+        """Long query should have higher complexity."""
+        long_query = "这是一个很长的问题" * 20
+        score = analyzer.analyze(long_query)
+
+        assert score >= 0.3
+
+    def test_analyze_multiple_conditions(self, analyzer):
+        """[AC-AISVC-RES-13] Query with multiple conditions should have high complexity."""
+        query = "查询订单状态和物流信息以及退款进度"
+        score = analyzer.analyze(query)
+
+        assert score >= 0.2
+
+    def test_analyze_reasoning_patterns(self, analyzer):
+        """Query with reasoning patterns should have higher complexity."""
+        query = "为什么订单会被取消？原因是什么？"
+        score = analyzer.analyze(query)
+
+        assert score >= 0.15
+
+    def test_analyze_cross_domain_patterns(self, analyzer):
+        """Cross-domain query should have higher complexity."""
+        query = "汇总所有部门的销售数据"
+        score = analyzer.analyze(query)
+
+        assert score >= 0.15
+
+    def test_analyze_multiple_questions(self, analyzer):
+        """Multiple questions should increase complexity."""
+        query = "什么是价格？如何购买？"
+        score = analyzer.analyze(query)
+
+        assert score >= 0.1
+
+
+class TestModeRouteResult:
+    """Tests for ModeRouteResult."""
+
+    def test_result_creation(self):
+        """Should create result with all fields."""
+        result = ModeRouteResult(
+            mode=RagRuntimeMode.REACT,
+            confidence=0.5,
+            complexity_score=0.7,
+            should_fallback_to_react=True,
+            fallback_reason="Low confidence",
+            diagnostics={"key": "value"},
+        )
+
+        assert result.mode == RagRuntimeMode.REACT
+        assert result.confidence == 0.5
+        assert result.complexity_score == 0.7
+        assert result.should_fallback_to_react is True
+        assert result.fallback_reason == "Low confidence"
+        assert result.diagnostics == {"key": "value"}
+
+    def test_result_defaults(self):
+        """Should create result with default values."""
+        result = ModeRouteResult(
+            mode=RagRuntimeMode.DIRECT,
+            confidence=0.8,
+            complexity_score=0.2,
+        )
+
+        assert result.should_fallback_to_react is False
+        assert result.fallback_reason is None
+        assert result.diagnostics == {}
+
+
+class TestModeRouter:
+    """[AC-AISVC-RES-09,10,11,12,13,14] Tests for ModeRouter."""
+
+    @pytest.fixture
+    def router(self):
+        reset_mode_router()
+        return ModeRouter()
+
+    def test_initial_config(self, router):
+        """Should initialize with default configuration."""
+        assert router.config.rag_runtime_mode == RagRuntimeMode.AUTO
+
+    def test_route_direct_mode(self, router):
+        """[AC-AISVC-RES-09] Should route to direct mode when configured."""
+        router._config.rag_runtime_mode = RagRuntimeMode.DIRECT
+
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        result = router.route(ctx)
+
+        assert result.mode == RagRuntimeMode.DIRECT
+
+    def test_route_react_mode(self, router):
+        """[AC-AISVC-RES-10] Should route to react mode when configured."""
+        router._config.rag_runtime_mode = RagRuntimeMode.REACT
+
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        result = router.route(ctx)
+
+        assert result.mode == RagRuntimeMode.REACT
+
+    def test_route_auto_mode_direct_conditions(self, router):
+        """[AC-AISVC-RES-11,12] Auto mode should select direct for simple queries."""
+        router._config.rag_runtime_mode = RagRuntimeMode.AUTO
+
+        ctx = StrategyContext(
+            tenant_id="tenant_a",
+            query="简单问题",
+            metadata_confidence=0.9,
+            complexity_score=0.1,
+        )
+
+        result = router.route(ctx)
+
+        assert result.mode == RagRuntimeMode.DIRECT
+
+    def test_route_auto_mode_react_low_confidence(self, router):
+        """[AC-AISVC-RES-11,12] Auto mode should select react for low confidence."""
+        router._config.rag_runtime_mode = RagRuntimeMode.AUTO
+        router._config.react_trigger_confidence_threshold = 0.6
+
+        ctx = StrategyContext(
+            tenant_id="tenant_a",
+            query="Test query",
+            metadata_confidence=0.4,
+            complexity_score=0.2,
+        )
+
+        result = router.route(ctx)
+
+        assert result.mode == RagRuntimeMode.REACT
+
+    def test_route_auto_mode_react_high_complexity(self, router):
+        """[AC-AISVC-RES-11,13] Auto mode should select react for high complexity."""
+        router._config.rag_runtime_mode = RagRuntimeMode.AUTO
+        router._config.react_trigger_complexity_score = 0.5
+
+        ctx = StrategyContext(
+            tenant_id="tenant_a",
+            query="Test query",
+            metadata_confidence=0.8,
+            complexity_score=0.7,
+        )
+
+        result = router.route(ctx)
+
+        assert result.mode == RagRuntimeMode.REACT
+
+    def test_update_config(self, router):
+        """[AC-AISVC-RES-15] Should update configuration."""
+        new_config = RoutingConfig(
+            rag_runtime_mode=RagRuntimeMode.REACT,
+            react_max_steps=7,
+        )
+
+        router.update_config(new_config)
+
+        assert router.config.rag_runtime_mode == RagRuntimeMode.REACT
+        assert router.config.react_max_steps == 7
+
+    @pytest.mark.asyncio
+    async def test_execute_direct(self, router):
+        """[AC-AISVC-RES-09] Should execute direct retrieval."""
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_result = MagicMock()
+        mock_result.hits = []
+
+        with patch.object(
+            router._direct_executor, "execute", new_callable=AsyncMock
+        ) as mock_execute:
+            mock_execute.return_value = mock_result
+
+            result = await router.execute_direct(ctx)
+
+            assert result == mock_result
+
+    @pytest.mark.asyncio
+    async def test_execute_with_fallback_no_fallback(self, router):
+        """[AC-AISVC-RES-14] Should not fallback when confidence is high."""
+        router._config.rag_runtime_mode = RagRuntimeMode.DIRECT
+        router._config.direct_fallback_on_low_confidence = True
+        router._config.direct_fallback_confidence_threshold = 0.4
+
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_result = MagicMock()
+        mock_hit = MagicMock()
+        mock_hit.score = 0.8
+        mock_result.hits = [mock_hit]
+
+        with patch.object(
+            router._direct_executor, "execute", new_callable=AsyncMock
+        ) as mock_execute:
+            mock_execute.return_value = mock_result
+
+            result, answer, route_result = await router.execute_with_fallback(ctx)
+
+            assert result == mock_result
+            assert answer is None
+            assert route_result.mode == RagRuntimeMode.DIRECT
+            assert route_result.should_fallback_to_react is False
+
+    @pytest.mark.asyncio
+    async def test_execute_with_fallback_triggered(self, router):
+        """[AC-AISVC-RES-14] Should fallback to react when confidence is low."""
+        router._config.rag_runtime_mode = RagRuntimeMode.DIRECT
+        router._config.direct_fallback_on_low_confidence = True
+        router._config.direct_fallback_confidence_threshold = 0.4
+
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_result = MagicMock()
+        mock_hit = MagicMock()
+        mock_hit.score = 0.2
+        mock_result.hits = [mock_hit]
+
+        with patch.object(
+            router._direct_executor, "execute", new_callable=AsyncMock
+        ) as mock_direct:
+            mock_direct.return_value = mock_result
+
+            with patch.object(
+                router._react_executor, "execute", new_callable=AsyncMock
+            ) as mock_react:
+                mock_react.return_value = ("Final answer", None, {})
+
+                result, answer, route_result = await router.execute_with_fallback(ctx)
+
+                assert result is None
+                assert answer == "Final answer"
+                assert route_result.mode == RagRuntimeMode.REACT
+                assert route_result.should_fallback_to_react is True
+                assert route_result.fallback_reason == "low_confidence"
+
+
+class TestSingletonInstances:
+    """Tests for singleton instance getters."""
+
+    def test_get_mode_router_singleton(self):
+        """Should return same router instance."""
+        reset_mode_router()
+
+        router1 = get_mode_router()
+        router2 = get_mode_router()
+
+        assert router1 is router2
+
+    def test_reset_mode_router(self):
+        """Should create new instance after reset."""
+        router1 = get_mode_router()
+        reset_mode_router()
+        router2 = get_mode_router()
+
+        assert router1 is not router2
diff --git a/ai-service/tests/test_routing_config.py b/ai-service/tests/test_routing_config.py
new file mode 100644
index 0000000..adc16f5
--- /dev/null
+++ b/ai-service/tests/test_routing_config.py
@@ -0,0 +1,253 @@
+"""
+Unit tests for Routing Configuration.
+[AC-AISVC-RES-01~15] Tests for strategy routing configuration models.
+"""
+
+import pytest
+
+from app.services.retrieval.routing_config import (
+    RagRuntimeMode,
+    StrategyType,
+    RoutingConfig,
+    StrategyContext,
+    StrategyResult,
+)
+
+
+class TestStrategyType:
+    """[AC-AISVC-RES-01,02] Tests for StrategyType enum."""
+
+    def test_strategy_type_default(self):
+        """[AC-AISVC-RES-01] Default strategy type should exist."""
+        assert StrategyType.DEFAULT.value == "default"
+
+    def test_strategy_type_enhanced(self):
+        """[AC-AISVC-RES-02] Enhanced strategy type should exist."""
+        assert StrategyType.ENHANCED.value == "enhanced"
+
+    def test_strategy_type_from_string(self):
+        """Should create StrategyType from string."""
+        assert StrategyType("default") == StrategyType.DEFAULT
+        assert StrategyType("enhanced") == StrategyType.ENHANCED
+
+
+class TestRagRuntimeMode:
+    """[AC-AISVC-RES-09,10,11] Tests for RagRuntimeMode enum."""
+
+    def test_mode_direct(self):
+        """[AC-AISVC-RES-09] Direct mode should exist."""
+        assert RagRuntimeMode.DIRECT.value == "direct"
+
+    def test_mode_react(self):
+        """[AC-AISVC-RES-10] React mode should exist."""
+        assert RagRuntimeMode.REACT.value == "react"
+
+    def test_mode_auto(self):
+        """[AC-AISVC-RES-11] Auto mode should exist."""
+        assert RagRuntimeMode.AUTO.value == "auto"
+
+    def test_mode_from_string(self):
+        """Should create RagRuntimeMode from string."""
+        assert RagRuntimeMode("direct") == RagRuntimeMode.DIRECT
+        assert RagRuntimeMode("react") == RagRuntimeMode.REACT
+        assert RagRuntimeMode("auto") == RagRuntimeMode.AUTO
+
+
+class TestRoutingConfig:
+    """[AC-AISVC-RES-01~15] Tests for RoutingConfig."""
+
+    def test_default_config(self):
+        """[AC-AISVC-RES-01] Default config should use default strategy and auto mode."""
+        config = RoutingConfig()
+
+        assert config.enabled is True
+        assert config.strategy == StrategyType.DEFAULT
+        assert config.rag_runtime_mode == RagRuntimeMode.AUTO
+        assert config.grayscale_percentage == 0.0
+        assert config.grayscale_allowlist == []
+
+    def test_config_with_custom_values(self):
+        """[AC-AISVC-RES-02,03] Config should accept custom values."""
+        config = RoutingConfig(
+            enabled=False,
+            strategy=StrategyType.ENHANCED,
+            rag_runtime_mode=RagRuntimeMode.REACT,
+            grayscale_percentage=0.3,
+            grayscale_allowlist=["tenant_a", "tenant_b"],
+        )
+
+        assert config.enabled is False
+        assert config.strategy == StrategyType.ENHANCED
+        assert config.rag_runtime_mode == RagRuntimeMode.REACT
+        assert config.grayscale_percentage == 0.3
+        assert "tenant_a" in config.grayscale_allowlist
+
+    def test_should_use_enhanced_strategy_default(self):
+        """[AC-AISVC-RES-01] Default strategy should not use enhanced."""
+        config = RoutingConfig()
+
+        assert config.should_use_enhanced_strategy("tenant_a") is False
+
+    def test_should_use_enhanced_strategy_explicit_enhanced(self):
+        """[AC-AISVC-RES-02] Explicit enhanced strategy should use enhanced for all tenants."""
+        config = RoutingConfig(strategy=StrategyType.ENHANCED)
+
+        assert config.should_use_enhanced_strategy("tenant_a") is True
+        assert config.should_use_enhanced_strategy("tenant_b") is True
+        assert config.should_use_enhanced_strategy(None) is True
+
+    def test_should_fallback_direct_to_react_disabled(self):
+        """[AC-AISVC-RES-14] Fallback should be disabled when configured."""
+        config = RoutingConfig(direct_fallback_on_low_confidence=False)
+
+        assert config.should_fallback_direct_to_react(0.1) is False
+        assert config.should_fallback_direct_to_react(0.0) is False
+
+    def test_should_fallback_direct_to_react_enabled(self):
+        """[AC-AISVC-RES-14] Fallback should trigger on low confidence."""
+        config = RoutingConfig(
+            direct_fallback_on_low_confidence=True,
+            direct_fallback_confidence_threshold=0.4,
+        )
+
+        assert config.should_fallback_direct_to_react(0.3) is True
+        assert config.should_fallback_direct_to_react(0.4) is False
+        assert config.should_fallback_direct_to_react(0.5) is False
+
+    def test_should_trigger_react_in_auto_mode_low_confidence(self):
+        """[AC-AISVC-RES-12] Low confidence should trigger react in auto mode."""
+        config = RoutingConfig(
+            react_trigger_confidence_threshold=0.6,
+        )
+
+        assert config.should_trigger_react_in_auto_mode(
+            confidence=0.5, complexity_score=0.3
+        ) is True
+        assert config.should_trigger_react_in_auto_mode(
+            confidence=0.7, complexity_score=0.3
+        ) is False
+
+    def test_should_trigger_react_in_auto_mode_high_complexity(self):
+        """[AC-AISVC-RES-13] High complexity should trigger react in auto mode."""
+        config = RoutingConfig(
+            react_trigger_complexity_score=0.5,
+        )
+
+        assert config.should_trigger_react_in_auto_mode(
+            confidence=0.8, complexity_score=0.6
+        ) is True
+        assert config.should_trigger_react_in_auto_mode(
+            confidence=0.8, complexity_score=0.4
+        ) is False
+
+    def test_validate_valid_config(self):
+        """[AC-AISVC-RES-06] Valid config should pass validation."""
+        config = RoutingConfig()
+
+        is_valid, errors = config.validate()
+
+        assert is_valid is True
+        assert len(errors) == 0
+
+    def test_validate_invalid_grayscale_percentage(self):
+        """[AC-AISVC-RES-06] Invalid grayscale percentage should fail validation."""
+        config = RoutingConfig(grayscale_percentage=1.5)
+
+        is_valid, errors = config.validate()
+
+        assert is_valid is False
+        assert any("grayscale_percentage" in e for e in errors)
+
+    def test_validate_invalid_confidence_threshold(self):
+        """[AC-AISVC-RES-06] Invalid confidence threshold should fail validation."""
+        config = RoutingConfig(react_trigger_confidence_threshold=1.5)
+
+        is_valid, errors = config.validate()
+
+        assert is_valid is False
+        assert any("react_trigger_confidence_threshold" in e for e in errors)
+
+    def test_validate_invalid_react_max_steps(self):
+        """[AC-AISVC-RES-06] Invalid react max steps should fail validation."""
+        config = RoutingConfig(react_max_steps=2)
+
+        is_valid, errors = config.validate()
+
+        assert is_valid is False
+        assert any("react_max_steps" in e for e in errors)
+
+    def test_validate_invalid_performance_budget(self):
+        """[AC-AISVC-RES-06] Invalid performance budget should fail validation."""
+        config = RoutingConfig(performance_budget_ms=500)
+
+        is_valid, errors = config.validate()
+
+        assert is_valid is False
+        assert any("performance_budget_ms" in e for e in errors)
+
+
+class TestStrategyContext:
+    """[AC-AISVC-RES-01~15] Tests for StrategyContext."""
+
+    def test_context_creation(self):
+        """Should create context with all fields."""
+        ctx = StrategyContext(
+            tenant_id="tenant_a",
+            query="Test query",
+            metadata_filter={"category": "product"},
+            metadata_confidence=0.8,
+            complexity_score=0.3,
+            kb_ids=["kb_1", "kb_2"],
+            top_k=10,
+        )
+
+        assert ctx.tenant_id == "tenant_a"
+        assert ctx.query == "Test query"
+        assert ctx.metadata_filter == {"category": "product"}
+        assert ctx.metadata_confidence == 0.8
+        assert ctx.complexity_score == 0.3
+        assert ctx.kb_ids == ["kb_1", "kb_2"]
+        assert ctx.top_k == 10
+
+    def test_context_minimal(self):
+        """Should create context with minimal fields."""
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        assert ctx.tenant_id == "tenant_a"
+        assert ctx.query == "Test query"
+        assert ctx.metadata_filter is None
+        assert ctx.metadata_confidence == 1.0
+        assert ctx.complexity_score == 0.0
+        assert ctx.kb_ids is None
+        assert ctx.top_k == 5
+
+
+class TestStrategyResult:
+    """[AC-AISVC-RES-01,02] Tests for StrategyResult."""
+
+    def test_result_creation(self):
+        """Should create result with all fields."""
+        result = StrategyResult(
+            strategy=StrategyType.ENHANCED,
+            mode=RagRuntimeMode.REACT,
+            should_fallback=True,
+            fallback_reason="Low confidence",
+            diagnostics={"key": "value"},
+        )
+
+        assert result.strategy == StrategyType.ENHANCED
+        assert result.mode == RagRuntimeMode.REACT
+        assert result.should_fallback is True
+        assert result.fallback_reason == "Low confidence"
+        assert result.diagnostics == {"key": "value"}
+
+    def test_result_defaults(self):
+        """Should create result with default values."""
+        result = StrategyResult(
+            strategy=StrategyType.DEFAULT,
+            mode=RagRuntimeMode.AUTO,
+        )
+
+        assert result.should_fallback is False
+        assert result.fallback_reason is None
+        assert result.diagnostics == {}
diff --git a/ai-service/tests/test_strategy_integration.py b/ai-service/tests/test_strategy_integration.py
new file mode 100644
index 0000000..affd181
--- /dev/null
+++ b/ai-service/tests/test_strategy_integration.py
@@ -0,0 +1,256 @@
+"""
+Unit tests for Retrieval Strategy Integration.
+[AC-AISVC-RES-01~15] Tests for integrated strategy and mode routing.
+"""
+
+import pytest
+from unittest.mock import AsyncMock, MagicMock, patch
+
+from app.services.retrieval.routing_config import (
+    RagRuntimeMode,
+    StrategyType,
+    RoutingConfig,
+    StrategyContext,
+)
+from app.services.retrieval.strategy_integration import (
+    RetrievalStrategyResult,
+    RetrievalStrategyIntegration,
+    get_retrieval_strategy_integration,
+    reset_retrieval_strategy_integration,
+)
+
+
+class TestRetrievalStrategyResult:
+    """Tests for RetrievalStrategyResult."""
+
+    def test_result_creation(self):
+        """Should create result with all fields."""
+        result = RetrievalStrategyResult(
+            retrieval_result=None,
+            final_answer="Test answer",
+            strategy=StrategyType.ENHANCED,
+            mode=RagRuntimeMode.REACT,
+            should_fallback=True,
+            fallback_reason="Low confidence",
+            diagnostics={"key": "value"},
+            duration_ms=100,
+        )
+
+        assert result.retrieval_result is None
+        assert result.final_answer == "Test answer"
+        assert result.strategy == StrategyType.ENHANCED
+        assert result.mode == RagRuntimeMode.REACT
+        assert result.should_fallback is True
+        assert result.fallback_reason == "Low confidence"
+        assert result.diagnostics == {"key": "value"}
+        assert result.duration_ms == 100
+
+    def test_result_defaults(self):
+        """Should create result with default values."""
+        result = RetrievalStrategyResult(
+            retrieval_result=None,
+            final_answer=None,
+            strategy=StrategyType.DEFAULT,
+            mode=RagRuntimeMode.DIRECT,
+        )
+
+        assert result.should_fallback is False
+        assert result.fallback_reason is None
+        assert result.mode_route_result is None
+        assert result.diagnostics == {}
+        assert result.duration_ms == 0
+
+
+class TestRetrievalStrategyIntegration:
+    """[AC-AISVC-RES-01~15] Tests for RetrievalStrategyIntegration."""
+
+    @pytest.fixture
+    def integration(self):
+        reset_retrieval_strategy_integration()
+        return RetrievalStrategyIntegration()
+
+    def test_initial_state(self, integration):
+        """Should initialize with default configuration."""
+        assert integration.config.strategy == StrategyType.DEFAULT
+        assert integration.config.rag_runtime_mode == RagRuntimeMode.AUTO
+
+    def test_update_config(self, integration):
+        """[AC-AISVC-RES-15] Should update all configurations."""
+        new_config = RoutingConfig(
+            strategy=StrategyType.ENHANCED,
+            rag_runtime_mode=RagRuntimeMode.REACT,
+            react_max_steps=7,
+        )
+
+        integration.update_config(new_config)
+
+        assert integration.config.strategy == StrategyType.ENHANCED
+        assert integration.config.rag_runtime_mode == RagRuntimeMode.REACT
+
+    def test_get_current_strategy(self, integration):
+        """Should return current strategy from router."""
+        strategy = integration.get_current_strategy()
+
+        assert strategy == StrategyType.DEFAULT
+
+    def test_get_rollback_records(self, integration):
+        """Should return rollback records from router."""
+        records = integration.get_rollback_records()
+
+        assert isinstance(records, list)
+
+    def test_validate_config(self, integration):
+        """[AC-AISVC-RES-06] Should validate configuration."""
+        is_valid, errors = integration.validate_config()
+
+        assert is_valid is True
+        assert len(errors) == 0
+
+    @pytest.mark.asyncio
+    async def test_execute_direct_mode(self, integration):
+        """[AC-AISVC-RES-09] Should execute direct mode."""
+        integration._config.rag_runtime_mode = RagRuntimeMode.DIRECT
+
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_result = MagicMock()
+        mock_result.hits = []
+
+        mock_route_result = MagicMock()
+        mock_route_result.mode = RagRuntimeMode.DIRECT
+
+        with patch.object(
+            integration._mode_router, "route", return_value=mock_route_result
+        ):
+            with patch.object(
+                integration._mode_router, "execute_with_fallback", new_callable=AsyncMock
+            ) as mock_execute:
+                mock_execute.return_value = (mock_result, None, mock_route_result)
+
+                result = await integration.execute(ctx)
+
+                assert result.retrieval_result == mock_result
+                assert result.final_answer is None
+                assert result.mode == RagRuntimeMode.DIRECT
+
+    @pytest.mark.asyncio
+    async def test_execute_react_mode(self, integration):
+        """[AC-AISVC-RES-10] Should execute react mode."""
+        integration._config.rag_runtime_mode = RagRuntimeMode.REACT
+
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_route_result = MagicMock()
+        mock_route_result.mode = RagRuntimeMode.REACT
+
+        with patch.object(
+            integration._mode_router, "route", return_value=mock_route_result
+        ):
+            with patch.object(
+                integration._mode_router, "execute_react", new_callable=AsyncMock
+            ) as mock_execute:
+                mock_execute.return_value = ("Final answer", None, {})
+
+                result = await integration.execute(ctx)
+
+                assert result.retrieval_result is None
+                assert result.final_answer == "Final answer"
+                assert result.mode == RagRuntimeMode.REACT
+
+    @pytest.mark.asyncio
+    async def test_execute_with_fallback(self, integration):
+        """[AC-AISVC-RES-14] Should handle fallback from direct to react."""
+        integration._config.rag_runtime_mode = RagRuntimeMode.DIRECT
+        integration._config.direct_fallback_on_low_confidence = True
+        integration._config.direct_fallback_confidence_threshold = 0.4
+
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_route_result = MagicMock()
+        mock_route_result.mode = RagRuntimeMode.DIRECT
+        mock_route_result.should_fallback_to_react = True
+        mock_route_result.fallback_reason = "low_confidence"
+
+        with patch.object(
+            integration._mode_router, "route", return_value=mock_route_result
+        ):
+            with patch.object(
+                integration._mode_router, "execute_with_fallback", new_callable=AsyncMock
+            ) as mock_execute:
+                mock_execute.return_value = (None, "Fallback answer", mock_route_result)
+
+                result = await integration.execute(ctx)
+
+                assert result.retrieval_result is None
+                assert result.final_answer == "Fallback answer"
+                assert result.should_fallback is True
+
+    @pytest.mark.asyncio
+    async def test_execute_includes_diagnostics(self, integration):
+        """Should include diagnostics in result."""
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_result = MagicMock()
+        mock_result.hits = []
+
+        mock_route_result = MagicMock()
+        mock_route_result.mode = RagRuntimeMode.DIRECT
+        mock_route_result.diagnostics = {"mode_key": "mode_value"}
+
+        with patch.object(
+            integration._mode_router, "route", return_value=mock_route_result
+        ):
+            with patch.object(
+                integration._mode_router, "execute_with_fallback", new_callable=AsyncMock
+            ) as mock_execute:
+                mock_execute.return_value = (mock_result, None, mock_route_result)
+
+                result = await integration.execute(ctx)
+
+                assert "strategy_diagnostics" in result.diagnostics
+                assert "mode_diagnostics" in result.diagnostics
+                assert "duration_ms" in result.diagnostics
+
+    @pytest.mark.asyncio
+    async def test_execute_tracks_duration(self, integration):
+        """Should track execution duration."""
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_result = MagicMock()
+        mock_result.hits = []
+
+        mock_route_result = MagicMock()
+        mock_route_result.mode = RagRuntimeMode.DIRECT
+
+        with patch.object(
+            integration._mode_router, "route", return_value=mock_route_result
+        ):
+            with patch.object(
+                integration._mode_router, "execute_with_fallback", new_callable=AsyncMock
+            ) as mock_execute:
+                mock_execute.return_value = (mock_result, None, mock_route_result)
+
+                result = await integration.execute(ctx)
+
+                assert result.duration_ms >= 0
+
+
+class TestSingletonInstances:
+    """Tests for singleton instance getters."""
+
+    def test_get_retrieval_strategy_integration_singleton(self):
+        """Should return same integration instance."""
+        reset_retrieval_strategy_integration()
+
+        integration1 = get_retrieval_strategy_integration()
+        integration2 = get_retrieval_strategy_integration()
+
+        assert integration1 is integration2
+
+    def test_reset_retrieval_strategy_integration(self):
+        """Should create new instance after reset."""
+        integration1 = get_retrieval_strategy_integration()
+        reset_retrieval_strategy_integration()
+        integration2 = get_retrieval_strategy_integration()
+
+        assert integration1 is not integration2
diff --git a/ai-service/tests/test_strategy_router.py b/ai-service/tests/test_strategy_router.py
new file mode 100644
index 0000000..850b8e9
--- /dev/null
+++ b/ai-service/tests/test_strategy_router.py
@@ -0,0 +1,344 @@
+"""
+Unit tests for Strategy Router.
+[AC-AISVC-RES-01,02,03,07,08] Tests for strategy routing, rollback, and grayscale release.
+"""
+
+import pytest
+from unittest.mock import AsyncMock, MagicMock, patch
+
+from app.services.retrieval.routing_config import (
+    RagRuntimeMode,
+    StrategyType,
+    RoutingConfig,
+    StrategyContext,
+)
+from app.services.retrieval.strategy_router import (
+    RollbackRecord,
+    RollbackManager,
+    DefaultPipeline,
+    EnhancedPipeline,
+    StrategyRouter,
+    get_strategy_router,
+    reset_strategy_router,
+)
+
+
+class TestRollbackRecord:
+    """[AC-AISVC-RES-07] Tests for RollbackRecord."""
+
+    def test_rollback_record_creation(self):
+        """Should create rollback record with all fields."""
+        record = RollbackRecord(
+            timestamp=1234567890.0,
+            from_strategy=StrategyType.ENHANCED,
+            to_strategy=StrategyType.DEFAULT,
+            reason="Performance issue",
+            tenant_id="tenant_a",
+            request_id="req_123",
+        )
+
+        assert record.timestamp == 1234567890.0
+        assert record.from_strategy == StrategyType.ENHANCED
+        assert record.to_strategy == StrategyType.DEFAULT
+        assert record.reason == "Performance issue"
+        assert record.tenant_id == "tenant_a"
+        assert record.request_id == "req_123"
+
+
+class TestRollbackManager:
+    """[AC-AISVC-RES-07] Tests for RollbackManager."""
+
+    @pytest.fixture
+    def manager(self):
+        return RollbackManager(max_records=10)
+
+    def test_record_rollback(self, manager):
+        """[AC-AISVC-RES-07] Should record rollback event."""
+        manager.record_rollback(
+            from_strategy=StrategyType.ENHANCED,
+            to_strategy=StrategyType.DEFAULT,
+            reason="Test rollback",
+            tenant_id="tenant_a",
+        )
+
+        records = manager.get_recent_rollbacks()
+        assert len(records) == 1
+        assert records[0].from_strategy == StrategyType.ENHANCED
+        assert records[0].to_strategy == StrategyType.DEFAULT
+        assert records[0].reason == "Test rollback"
+
+    def test_max_records_limit(self, manager):
+        """Should limit number of records."""
+        for i in range(15):
+            manager.record_rollback(
+                from_strategy=StrategyType.ENHANCED,
+                to_strategy=StrategyType.DEFAULT,
+                reason=f"Reason {i}",
+            )
+
+        records = manager.get_recent_rollbacks(limit=20)
+        assert len(records) == 10
+
+    def test_get_rollback_count(self, manager):
+        """Should count rollbacks correctly."""
+        import time
+
+        now = time.time()
+
+        manager.record_rollback(
+            from_strategy=StrategyType.ENHANCED,
+            to_strategy=StrategyType.DEFAULT,
+            reason="Reason 1",
+        )
+
+        assert manager.get_rollback_count() == 1
+        assert manager.get_rollback_count(since_timestamp=now) == 1
+        assert manager.get_rollback_count(since_timestamp=now + 10) == 0
+
+
+class TestDefaultPipeline:
+    """[AC-AISVC-RES-01] Tests for DefaultPipeline."""
+
+    @pytest.mark.asyncio
+    async def test_execute_uses_optimized_retriever(self):
+        """[AC-AISVC-RES-01] Default pipeline should use OptimizedRetriever."""
+        pipeline = DefaultPipeline()
+
+        ctx = StrategyContext(
+            tenant_id="tenant_a",
+            query="Test query",
+        )
+
+        mock_result = MagicMock()
+        mock_result.hits = []
+
+        with patch(
+            "app.services.retrieval.optimized_retriever.get_optimized_retriever",
+            new_callable=AsyncMock,
+        ) as mock_get_retriever:
+            mock_retriever = AsyncMock()
+            mock_retriever.retrieve.return_value = mock_result
+            mock_get_retriever.return_value = mock_retriever
+
+            result = await pipeline.execute(ctx)
+
+            assert result == mock_result
+            mock_retriever.retrieve.assert_called_once()
+
+
+class TestEnhancedPipeline:
+    """[AC-AISVC-RES-02] Tests for EnhancedPipeline."""
+
+    @pytest.mark.asyncio
+    async def test_execute_creates_optimized_retriever(self):
+        """[AC-AISVC-RES-02] Enhanced pipeline should create OptimizedRetriever with enhanced config."""
+        config = RoutingConfig(strategy=StrategyType.ENHANCED)
+        pipeline = EnhancedPipeline(config=config)
+
+        ctx = StrategyContext(
+            tenant_id="tenant_a",
+            query="Test query",
+        )
+
+        mock_result = MagicMock()
+        mock_result.hits = []
+
+        mock_retriever = AsyncMock()
+        mock_retriever.retrieve.return_value = mock_result
+
+        with patch(
+            "app.services.retrieval.optimized_retriever.OptimizedRetriever",
+            return_value=mock_retriever,
+        ) as mock_retriever_class:
+            result = await pipeline.execute(ctx)
+
+            mock_retriever_class.assert_called_once_with(
+                two_stage_enabled=True,
+                hybrid_enabled=True,
+            )
+            assert result == mock_result
+
+
+class TestStrategyRouter:
+    """[AC-AISVC-RES-01,02,03,07,08] Tests for StrategyRouter."""
+
+    @pytest.fixture
+    def router(self):
+        reset_strategy_router()
+        return StrategyRouter()
+
+    def test_initial_state(self, router):
+        """[AC-AISVC-RES-01] Initial state should be default strategy."""
+        assert router.current_strategy == StrategyType.DEFAULT
+        assert router.config.enabled is True
+
+    def test_route_default_strategy(self, router):
+        """[AC-AISVC-RES-01] Should route to default strategy by default."""
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        result = router.route(ctx)
+
+        assert result.strategy == StrategyType.DEFAULT
+        assert router.current_strategy == StrategyType.DEFAULT
+
+    def test_route_enhanced_strategy_explicit(self, router):
+        """[AC-AISVC-RES-02] Should route to enhanced when explicitly configured."""
+        router._config.strategy = StrategyType.ENHANCED
+
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        result = router.route(ctx)
+
+        assert result.strategy == StrategyType.ENHANCED
+        assert router.current_strategy == StrategyType.ENHANCED
+
+    def test_route_grayscale_allowlist(self, router):
+        """[AC-AISVC-RES-03] Should route to enhanced for tenants in allowlist."""
+        router._config.strategy = StrategyType.ENHANCED
+        router._config.grayscale_allowlist = ["tenant_a", "tenant_b"]
+
+        ctx_a = StrategyContext(tenant_id="tenant_a", query="Test query")
+        ctx_c = StrategyContext(tenant_id="tenant_c", query="Test query")
+
+        result_a = router.route(ctx_a)
+        result_c = router.route(ctx_c)
+
+        assert result_a.strategy == StrategyType.ENHANCED
+        assert result_c.strategy == StrategyType.ENHANCED
+
+    def test_route_disabled_strategy(self, router):
+        """Should use default when strategy is disabled."""
+        router._strategy_enabled = False
+
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        result = router.route(ctx)
+
+        assert result.strategy == StrategyType.DEFAULT
+
+    def test_update_config(self, router):
+        """[AC-AISVC-RES-15] Should update configuration."""
+        new_config = RoutingConfig(
+            strategy=StrategyType.ENHANCED,
+            rag_runtime_mode=RagRuntimeMode.REACT,
+        )
+
+        router.update_config(new_config)
+
+        assert router.config.strategy == StrategyType.ENHANCED
+        assert router.config.rag_runtime_mode == RagRuntimeMode.REACT
+
+    def test_rollback(self, router):
+        """[AC-AISVC-RES-07] Should rollback to default strategy."""
+        router._current_strategy = StrategyType.ENHANCED
+        router._config.strategy = StrategyType.ENHANCED
+
+        router.rollback(reason="Test rollback", tenant_id="tenant_a")
+
+        assert router.current_strategy == StrategyType.DEFAULT
+        assert router.config.strategy == StrategyType.DEFAULT
+
+        records = router.get_rollback_records()
+        assert len(records) == 1
+        assert records[0].reason == "Test rollback"
+
+    def test_rollback_from_default_no_op(self, router):
+        """[AC-AISVC-RES-07] Rollback from default should be no-op."""
+        router.rollback(reason="Test rollback")
+
+        assert router.current_strategy == StrategyType.DEFAULT
+        records = router.get_rollback_records()
+        assert len(records) == 0
+
+    def test_validate_config(self, router):
+        """[AC-AISVC-RES-06] Should validate configuration."""
+        is_valid, errors = router.validate_config()
+
+        assert is_valid is True
+        assert len(errors) == 0
+
+    @pytest.mark.asyncio
+    async def test_execute_default_strategy(self, router):
+        """[AC-AISVC-RES-01] Should execute default pipeline."""
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_result = MagicMock()
+        mock_result.hits = []
+
+        with patch.object(
+            router._default_pipeline, "execute", new_callable=AsyncMock
+        ) as mock_execute:
+            mock_execute.return_value = mock_result
+
+            result, strategy_result = await router.execute(ctx)
+
+            assert result == mock_result
+            assert strategy_result.strategy == StrategyType.DEFAULT
+            mock_execute.assert_called_once_with(ctx)
+
+    @pytest.mark.asyncio
+    async def test_execute_enhanced_strategy(self, router):
+        """[AC-AISVC-RES-02] Should execute enhanced pipeline."""
+        router._config.strategy = StrategyType.ENHANCED
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_result = MagicMock()
+        mock_result.hits = []
+
+        with patch.object(
+            router._enhanced_pipeline, "execute", new_callable=AsyncMock
+        ) as mock_execute:
+            mock_execute.return_value = mock_result
+
+            result, strategy_result = await router.execute(ctx)
+
+            assert result == mock_result
+            assert strategy_result.strategy == StrategyType.ENHANCED
+            mock_execute.assert_called_once_with(ctx)
+
+    @pytest.mark.asyncio
+    async def test_execute_fallback_on_error(self, router):
+        """[AC-AISVC-RES-07] Should fallback to default on enhanced failure."""
+        router._config.strategy = StrategyType.ENHANCED
+        ctx = StrategyContext(tenant_id="tenant_a", query="Test query")
+
+        mock_result = MagicMock()
+        mock_result.hits = []
+
+        with patch.object(
+            router._enhanced_pipeline, "execute", new_callable=AsyncMock
+        ) as mock_enhanced:
+            mock_enhanced.side_effect = Exception("Enhanced pipeline failed")
+
+            with patch.object(
+                router._default_pipeline, "execute", new_callable=AsyncMock
+            ) as mock_default:
+                mock_default.return_value = mock_result
+
+                result, strategy_result = await router.execute(ctx)
+
+                assert result == mock_result
+                assert strategy_result.strategy == StrategyType.DEFAULT
+                assert strategy_result.should_fallback is True
+                assert "Enhanced pipeline failed" in strategy_result.fallback_reason
+
+
+class TestSingletonInstances:
+    """Tests for singleton instance getters."""
+
+    def test_get_strategy_router_singleton(self):
+        """Should return same router instance."""
+        reset_strategy_router()
+
+        router1 = get_strategy_router()
+        router2 = get_strategy_router()
+
+        assert router1 is router2
+
+    def test_reset_strategy_router(self):
+        """Should create new instance after reset."""
+        router1 = get_strategy_router()
+        reset_strategy_router()
+        router2 = get_strategy_router()
+
+        assert router1 is not router2