diff --git a/src/Test/L1/Worker/NodeSelectionL1Tests.cs b/src/Test/L1/Worker/NodeSelectionL1Tests.cs
new file mode 100644
index 0000000000..1054195cdd
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+++ b/src/Test/L1/Worker/NodeSelectionL1Tests.cs
@@ -0,0 +1,369 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.TeamFoundation.DistributedTask.WebApi;
+using Microsoft.VisualStudio.Services.Agent.Util;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Microsoft.VisualStudio.Services.Agent.Tests.L1.Worker
+{
+    [Collection("Worker L1 Tests")]
+    public class NodeSelectionL1Tests : L1TestBase
+    {
+        private const string AGENT_USE_NODE24 = "AGENT_USE_NODE24";
+        private const string AGENT_USE_NODE20_1 = "AGENT_USE_NODE20_1";
+        private const string AGENT_RESTRICT_EOL_NODE_VERSIONS = "AGENT_RESTRICT_EOL_NODE_VERSIONS";
+        private const string AGENT_USE_NODE_STRATEGY = "AGENT_USE_NODE_STRATEGY";
+        private const string NODE24_FOLDER = "node24";
+        private const string NODE20_1_FOLDER = "node20_1";
+        private const string NODE16_FOLDER = "node16";
+        private const string NODE_SELECTION_LOG_PATTERN = "Using node path:";
+        private const string NODE20_LOG_PATTERN = "node20";
+        
+
+        /// <summary>
+        /// Verifies that node selection process was initiated and logs were generated.
+        /// Note: This tests observable behavior through logs since L1 tests run the full worker pipeline.
+        /// Unit tests should test the orchestrator/strategy interfaces directly.
+        /// </summary>
+        private void AssertNodeSelectionAttempted(IEnumerable<string> log, TaskResult result, bool useStrategy, string context = "")
+        {
+            string modeDescription = $"{(useStrategy ? "strategy" : "legacy")} mode{(string.IsNullOrEmpty(context) ? "" : $" - {context}")}";
+            
+            bool hasNodeSelection;
+            if (useStrategy)
+            {
+                // Strategy mode: Verify orchestrator was invoked
+                hasNodeSelection = log.Any(x => x.Contains("[Host] Selected Node version:") && x.Contains("(Strategy:")) ||
+                                   log.Any(x => x.Contains("[Host] Node path:")) ||
+                                   log.Any(x => x.Contains("[Host] Starting node version selection")) ||
+                                   log.Any(x => x.Contains(NODE_SELECTION_LOG_PATTERN));
+            }
+            else
+            {
+                // Legacy mode: Verify traditional node handler was used
+                hasNodeSelection = log.Any(x => x.Contains(NODE_SELECTION_LOG_PATTERN));
+            }
+            
+            Assert.True(hasNodeSelection, $"Node selection process should be initiated: {modeDescription}");
+            
+            Assert.Equal(TaskResult.Succeeded, result);
+        }
+        
+        /// <summary>
+        /// Verifies that the expected Node version was selected and is reflected in logs.
+        /// This validates the end-to-end selection result in L1 integration testing.
+        /// </summary>
+        private void AssertNodeSelectionSuccess(IEnumerable<string> log, string expectedPattern, bool useStrategy, string context = "")
+        {
+            string modeDescription = $"{(useStrategy ? "strategy" : "legacy")} mode{(string.IsNullOrEmpty(context) ? "" : $" - {context}")}";
+            
+            bool hasExpectedSelection;
+            if (useStrategy)
+            {
+                // Strategy mode: Verify orchestrator selected the expected version
+                hasExpectedSelection = log.Any(x => 
+                    (x.Contains("[Host] Selected Node version:") || x.Contains("[Host] Node path:") || x.Contains(NODE_SELECTION_LOG_PATTERN)) && 
+                    x.Contains(expectedPattern));
+            }
+            else
+            {
+                // Legacy mode: Verify legacy handler selected the expected version
+                hasExpectedSelection = log.Any(x => x.Contains(NODE_SELECTION_LOG_PATTERN) && x.Contains(expectedPattern));
+            }
+            
+            Assert.True(hasExpectedSelection, $"Expected node selection '{expectedPattern}' should be reflected in execution logs: {modeDescription}");
+        }
+        
+        [Theory]
+        [Trait("Level", "L1")]
+        [Trait("Category", "Worker")]
+        [Trait("SkipOn", "windows")]
+        [InlineData(AGENT_USE_NODE24, "true", NODE24_FOLDER, false)] // Legacy mode
+        [InlineData(AGENT_USE_NODE20_1, "true", NODE20_1_FOLDER, false)]
+        [InlineData(AGENT_USE_NODE24, "true", NODE24_FOLDER, true)]  // Strategy mode
+        [InlineData(AGENT_USE_NODE20_1, "true", NODE20_1_FOLDER, true)]
+        public async Task NodeSelection_EnvironmentKnobs_SelectsCorrectVersion_NonWindows(string knob, string value, string expectedNodeFolder, bool useStrategy)
+        {
+            try
+            {
+                SetupL1();
+                ClearNodeEnvironmentVariables();
+                Environment.SetEnvironmentVariable(knob, value);
+                Environment.SetEnvironmentVariable(AGENT_USE_NODE_STRATEGY, useStrategy.ToString().ToLower());
+                
+                var message = LoadTemplateMessage();
+                message.Steps.Clear();
+                message.Steps.Add(CreateScriptTask($"echo Testing node selection - {(useStrategy ? "strategy" : "legacy")} mode"));
+
+                var results = await RunWorker(message);
+
+                AssertJobCompleted();
+                
+                var steps = GetSteps();
+                var taskStep = steps.FirstOrDefault(s => s.Name == "CmdLine");
+                Assert.NotNull(taskStep);
+
+                var log = GetTimelineLogLines(taskStep);
+
+                AssertNodeSelectionAttempted(log, results.Result, useStrategy, $"testing {knob}");
+                
+                string expectedLogPattern = expectedNodeFolder == NODE20_1_FOLDER ? NODE20_LOG_PATTERN : expectedNodeFolder;
+                AssertNodeSelectionSuccess(log, expectedLogPattern, useStrategy, $"{expectedNodeFolder}");
+            }
+            finally
+            {
+                ClearNodeEnvironmentVariables();
+                TearDown();
+            }
+        }
+        
+        [Theory]
+        [Trait("Level", "L1")]
+        [Trait("Category", "Worker")]
+        [Trait("SkipOn", "linux")]
+        [Trait("SkipOn", "darwin")]
+        [InlineData(AGENT_USE_NODE24, "true", NODE24_FOLDER, false)] // Legacy mode
+        [InlineData(AGENT_USE_NODE20_1, "true", NODE20_1_FOLDER, false)]
+        [InlineData(AGENT_USE_NODE24, "true", NODE24_FOLDER, true)]  // Strategy mode
+        [InlineData(AGENT_USE_NODE20_1, "true", NODE20_1_FOLDER, true)]
+        public async Task NodeSelection_EnvironmentKnobs_SelectsCorrectVersion_Windows(string knob, string value, string expectedNodeFolder, bool useStrategy)
+        {
+            try
+            {
+                SetupL1();
+                ClearNodeEnvironmentVariables();
+                Environment.SetEnvironmentVariable(knob, value);
+                Environment.SetEnvironmentVariable(AGENT_USE_NODE_STRATEGY, useStrategy.ToString().ToLower());
+                
+                var message = LoadTemplateMessage();
+                message.Steps.Clear();
+                message.Steps.Add(CreateScriptTask($"echo Testing node selection - {(useStrategy ? "strategy" : "legacy")} mode"));
+
+                var results = await RunWorker(message);
+
+                AssertJobCompleted();
+                Assert.Equal(TaskResult.Succeeded, results.Result);
+                
+                var steps = GetSteps();
+                var taskStep = steps.FirstOrDefault(s => s.Name == "CmdLine");
+                Assert.NotNull(taskStep);
+
+                // On Windows, CmdLine uses PowerShell, so Node.js environment variables don't affect execution
+            }
+            finally
+            {
+                ClearNodeEnvironmentVariables();
+                TearDown();
+            }
+        }
+
+        [Theory]
+        [Trait("Level", "L1")]
+        [Trait("Category", "Worker")]
+        [Trait("SkipOn", "windows")]  // Skip on Windows - uses PowerShell, not Node.js
+        [InlineData(false)] // Legacy mode
+        [InlineData(true)]  // Strategy mode
+        public async Task NodeSelection_DefaultBehavior_UsesAppropriateVersion_NonWindows(bool useStrategy)
+        {
+            try
+            {
+                SetupL1();
+                ClearNodeEnvironmentVariables();
+                Environment.SetEnvironmentVariable(AGENT_USE_NODE_STRATEGY, useStrategy.ToString().ToLower());
+                
+                var message = LoadTemplateMessage();
+                message.Steps.Clear();
+                message.Steps.Add(CreateScriptTask($"echo Testing default node selection - {(useStrategy ? "strategy" : "legacy")} mode"));
+
+                var results = await RunWorker(message);
+
+                AssertJobCompleted();
+                
+                var steps = GetSteps();
+                var taskStep = steps.FirstOrDefault(s => s.Name == "CmdLine");
+                Assert.NotNull(taskStep);
+
+                var log = GetTimelineLogLines(taskStep);
+                
+                AssertNodeSelectionAttempted(log, results.Result, useStrategy, "default behavior");
+                
+                Assert.Equal(TaskResult.Succeeded, results.Result);
+                bool usesCompatibleVersion = log.Any(x => x.Contains(NODE_SELECTION_LOG_PATTERN) && 
+                    (x.Contains(NODE20_LOG_PATTERN) || x.Contains(NODE16_FOLDER) || x.Contains(NODE24_FOLDER)));
+                Assert.True(usesCompatibleVersion, $"Should select compatible node version - {(useStrategy ? "strategy" : "legacy")} mode");
+            }
+            finally
+            {
+                ClearNodeEnvironmentVariables();
+                TearDown();
+            }
+        }
+
+        [Theory]
+        [Trait("Level", "L1")]
+        [Trait("Category", "Worker")]
+        [Trait("SkipOn", "windows")]
+        [InlineData(true)]
+        [InlineData(false)]
+        public async Task NodeSelection_StrategyVsLegacy_ProducesExpectedBehavior_NonWindows(bool useStrategy)
+        {
+            try
+            {
+                SetupL1();
+                ClearNodeEnvironmentVariables();
+                
+                Environment.SetEnvironmentVariable(AGENT_USE_NODE_STRATEGY, useStrategy.ToString().ToLower());
+                Environment.SetEnvironmentVariable(AGENT_USE_NODE24, "true");
+                
+                var message = LoadTemplateMessage();
+                message.Steps.Clear();
+                message.Steps.Add(CreateScriptTask("echo Testing strategy vs legacy"));
+
+                var results = await RunWorker(message);
+
+                AssertJobCompleted();
+                
+                Assert.Equal(TaskResult.Succeeded, results.Result);
+                
+                var steps = GetSteps();
+                var taskStep = steps.FirstOrDefault(s => s.Name == "CmdLine");
+                Assert.NotNull(taskStep);
+
+                var log = GetTimelineLogLines(taskStep);
+
+                bool hasNodeSelection;
+                if (useStrategy)
+                {
+                    hasNodeSelection = log.Any(x => x.Contains("[Host] Selected Node version:") || 
+                                                   x.Contains("[Host] Node path:") || 
+                                                   x.Contains(NODE_SELECTION_LOG_PATTERN));
+                }
+                else
+                {
+                    hasNodeSelection = log.Any(x => x.Contains(NODE_SELECTION_LOG_PATTERN));
+                }
+                Assert.True(hasNodeSelection, $"Expected node selection log for {(useStrategy ? "strategy" : "legacy")} mode");
+
+                bool usesNode24 = log.Any(x => (x.Contains("[Host] Selected Node version:") || 
+                                               x.Contains("[Host] Node path:") || 
+                                               x.Contains(NODE_SELECTION_LOG_PATTERN)) && 
+                                              x.Contains(NODE24_FOLDER));
+                Assert.True(usesNode24, "Should use node24 based on AGENT_USE_NODE24=true");
+            }
+            finally
+            {
+                ClearNodeEnvironmentVariables();
+                TearDown();
+            }
+        }
+
+        [Theory]
+        [Trait("Level", "L1")]
+        [Trait("Category", "Worker")]
+        [Trait("SkipOn", "windows")]
+        [InlineData(AGENT_USE_NODE24, AGENT_USE_NODE20_1, NODE24_FOLDER, false)] // Legacy mode - node24 should win
+        [InlineData(AGENT_USE_NODE24, AGENT_USE_NODE20_1, NODE24_FOLDER, true)]  // Strategy mode - node24 should win
+        public async Task NodeSelection_ConflictingKnobs_HigherVersionWins(string winningKnob, string losingKnob, string expectedNodeFolder, bool useStrategy)
+        {
+            try
+            {
+                SetupL1();
+                ClearNodeEnvironmentVariables();
+                
+                Environment.SetEnvironmentVariable(winningKnob, "true");
+                Environment.SetEnvironmentVariable(losingKnob, "true");
+                Environment.SetEnvironmentVariable(AGENT_USE_NODE_STRATEGY, useStrategy.ToString().ToLower());
+                
+                var message = LoadTemplateMessage();
+                message.Steps.Clear();
+                message.Steps.Add(CreateScriptTask($"echo Testing conflicting knobs - {(useStrategy ? "strategy" : "legacy")} mode"));
+
+                var results = await RunWorker(message);
+
+                AssertJobCompleted();
+                
+                var steps = GetSteps();
+                var taskStep = steps.FirstOrDefault(s => s.Name == "CmdLine");
+                Assert.NotNull(taskStep);
+
+                var log = GetTimelineLogLines(taskStep);
+                AssertNodeSelectionAttempted(log, results.Result, useStrategy, "conflicting knobs");
+                
+                string expectedLogPattern = expectedNodeFolder == NODE20_1_FOLDER ? NODE20_LOG_PATTERN : expectedNodeFolder;
+                AssertNodeSelectionSuccess(log, expectedLogPattern, useStrategy, "conflicting knobs resolution");
+            }
+            finally
+            {
+                ClearNodeEnvironmentVariables();
+                TearDown();
+            }
+        }
+
+        [Theory]
+        [Trait("Level", "L1")]
+        [Trait("Category", "Worker")]
+        [Trait("SkipOn", "windows")]
+        [Trait("SkipOn", "darwin")]
+        [InlineData(false)] // Legacy mode
+        [InlineData(true)]  // Strategy mode
+        public async Task NodeSelection_GlibcFallback_FallsBackToCompatibleVersion(bool useStrategy)
+        {
+            try
+            {
+                SetupL1();
+                ClearNodeEnvironmentVariables();
+                
+                Environment.SetEnvironmentVariable(AGENT_USE_NODE24, "true");
+                Environment.SetEnvironmentVariable(AGENT_USE_NODE_STRATEGY, useStrategy.ToString().ToLower());
+                
+                var message = LoadTemplateMessage();
+                message.Steps.Clear();
+                message.Steps.Add(CreateScriptTask($"echo Testing glibc compatibility - {(useStrategy ? "strategy" : "legacy")} mode"));
+
+                var results = await RunWorker(message);
+
+                AssertJobCompleted();
+                
+                var steps = GetSteps();
+                var taskStep = steps.FirstOrDefault(s => s.Name == "CmdLine");
+                Assert.NotNull(taskStep);
+
+                var log = GetTimelineLogLines(taskStep);
+                AssertNodeSelectionAttempted(log, results.Result, useStrategy, "glibc compatibility");
+                
+                var usedCompatibleNode = log.Any(x => x.Contains(NODE_SELECTION_LOG_PATTERN) && 
+                    (x.Contains(NODE24_FOLDER) || x.Contains(NODE20_LOG_PATTERN) || x.Contains(NODE16_FOLDER)));
+                Assert.True(usedCompatibleNode, $"Should select glibc-compatible node version - {(useStrategy ? "strategy" : "legacy")} mode");
+                
+                var hasNode24ToNode20Fallback = log.Any(x => x.Contains(NODE_SELECTION_LOG_PATTERN) && 
+                    x.Contains(NODE20_LOG_PATTERN) && !x.Contains(NODE24_FOLDER));
+                if (hasNode24ToNode20Fallback)
+                {
+                    string expectedGlibcWarning = StringUtil.Loc("NodeGlibcFallbackWarning", "agent", "Node24", "Node20");
+                    var hasGlibcWarning = log.Any(x => x.Contains(expectedGlibcWarning));
+                    Assert.True(hasGlibcWarning, $"Should show glibc fallback warning - {(useStrategy ? "strategy" : "legacy")} mode");
+                }
+            }
+            finally
+            {
+                ClearNodeEnvironmentVariables();
+                TearDown();
+            }
+        }
+
+        private void ClearNodeEnvironmentVariables()
+        {
+            Environment.SetEnvironmentVariable(AGENT_USE_NODE24, null);
+            Environment.SetEnvironmentVariable(AGENT_USE_NODE20_1, null);
+            Environment.SetEnvironmentVariable(AGENT_USE_NODE_STRATEGY, null);
+            Environment.SetEnvironmentVariable(AGENT_RESTRICT_EOL_NODE_VERSIONS, null);
+        }
+
+    }
+}
\ No newline at end of file