Change CLI flag --LogLevel to --log-level

src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs

@@ -316,7 +316,7 @@ private void HandleListTools(JsonElement? id)
         /// <remarks>
         /// Log level precedence (highest to lowest):
         /// 1. MCP <c>logging/setLevel</c> (Agent) - always wins, overrides CLI and Config.
-        /// 2. CLI <c>--LogLevel</c> flag.
+        /// 2. CLI <c>--log-level</c> flag.
         /// 3. Config <c>runtime.telemetry.log-level</c>.
         /// 4. Default: <c>None</c> for MCP stdio mode (silent by default to keep stdout clean for JSON-RPC),
         ///    <c>Error</c> in Production, <c>Debug</c> in Development.
@@ -334,7 +334,7 @@ private void HandleListTools(JsonElement? id)
         ///    hot-reloads do not overwrite the agent's choice.
         /// 3. Restore <see cref="Console.Error"/> to the real stderr stream when logging is enabled,
         ///    in case startup redirected it to <see cref="TextWriter.Null"/> (default for
-        ///    <c>--mcp-stdio</c> or <c>--LogLevel none</c>).
+        ///    <c>--mcp-stdio</c> or <c>--log-level none</c>).
         /// </remarks>
         private void HandleSetLogLevel(JsonElement? id, JsonElement root)
         {
@@ -393,7 +393,7 @@ private void HandleSetLogLevel(JsonElement? id, JsonElement root)
             bool updated = logLevelController.UpdateFromMcp(level);
 
             // Restore stderr if the agent successfully turned logging on. When `--mcp-stdio` (or
-            // `--LogLevel none`) was the startup default, stderr was redirected to TextWriter.Null;
+            // `--log-level none`) was the startup default, stderr was redirected to TextWriter.Null;
             // re-enable it now so subsequent logs flow.
             if (updated && isLoggingEnabled)
             {

src/Cli.Tests/CustomLoggerTests.cs

@@ -6,7 +6,7 @@ namespace Cli.Tests;
 /// <summary>
 /// Tests for <see cref="CustomLoggerProvider"/> covering both the standard CLI
 /// path (writes to stdout/stderr with abbreviated labels) and the MCP stdio path
-/// (suppressed by default, opt-in via either CLI <c>--LogLevel</c> or the
+/// (suppressed by default, opt-in via either CLI <c>--log-level</c> or the
 /// runtime config's <c>log-level</c>, always routed to stderr to keep the
 /// JSON-RPC channel on stdout uncorrupted).
 /// </summary>
@@ -85,7 +85,7 @@ public void LogOutput_UsesAbbreviatedLogLevelLabels(LogLevel logLevel, string ex
     }
 
     /// <summary>
-    /// MCP stdio mode with no overrides (neither CLI <c>--LogLevel</c> nor
+    /// MCP stdio mode with no overrides (neither CLI <c>--log-level</c> nor
     /// config <c>log-level</c>): all output must be suppressed so the JSON-RPC
     /// channel stays clean.
     /// </summary>
@@ -106,7 +106,7 @@ public void Mcp_NoOverrides_SuppressesAllOutput()
     }
 
     /// <summary>
-    /// MCP stdio mode with a CLI-supplied <c>--LogLevel</c>: logs must always
+    /// MCP stdio mode with a CLI-supplied <c>--log-level</c>: logs must always
     /// go to stderr (never stdout) and the level threshold from
     /// <see cref="Cli.Utils.CliLogLevel"/> must be honored.
     /// </summary>

src/Cli.Tests/EndToEndTests.cs

@@ -814,23 +814,25 @@ public Task TestUpdatingStoredProcedureWithRestMethods()
     }
 
     /// <summary>
-    /// Test to validate that the engine starts successfully when --verbose and --LogLevel
+    /// Test to validate that the engine starts successfully when --verbose and --log-level
     /// options are used with the start command
     /// This test does not validate whether the engine logs messages at the specified log level
     /// </summary>
     /// <param name="logLevelOption">Log level options</param>
     [DataTestMethod]
     [DataRow("", DisplayName = "No logging from command line.")]
     [DataRow("--verbose", DisplayName = "Verbose logging from command line.")]
-    [DataRow("--LogLevel 0", DisplayName = "LogLevel 0 from command line.")]
-    [DataRow("--LogLevel 1", DisplayName = "LogLevel 1 from command line.")]
-    [DataRow("--LogLevel 2", DisplayName = "LogLevel 2 from command line.")]
-    [DataRow("--LogLevel Trace", DisplayName = "LogLevel Trace from command line.")]
-    [DataRow("--LogLevel Debug", DisplayName = "LogLevel Debug from command line.")]
-    [DataRow("--LogLevel Information", DisplayName = "LogLevel Information from command line.")]
-    [DataRow("--LogLevel tRace", DisplayName = "Case sensitivity: LogLevel Trace from command line.")]
-    [DataRow("--LogLevel DebUG", DisplayName = "Case sensitivity: LogLevel Debug from command line.")]
-    [DataRow("--LogLevel information", DisplayName = "Case sensitivity: LogLevel Information from command line.")]
+    [DataRow("--log-level 0", DisplayName = "LogLevel 0 from command line.")]
+    [DataRow("--log-level 1", DisplayName = "LogLevel 1 from command line.")]
+    [DataRow("--log-level 2", DisplayName = "LogLevel 2 from command line.")]
+    [DataRow("--log-level Trace", DisplayName = "LogLevel Trace from command line.")]
+    [DataRow("--log-level Debug", DisplayName = "LogLevel Debug from command line.")]
+    [DataRow("--log-level Information", DisplayName = "LogLevel Information from command line.")]
+    [DataRow("--log-level tRace", DisplayName = "Case sensitivity: LogLevel Trace from command line.")]
+    [DataRow("--log-level DebUG", DisplayName = "Case sensitivity: LogLevel Debug from command line.")]
+    [DataRow("--log-level information", DisplayName = "Case sensitivity: LogLevel Information from command line.")]
+    [DataRow("--LogLevel 0", DisplayName = "Case sensitivity: LogLevel 0 legacy from command line.")]
+    [DataRow("--LogLevel information", DisplayName = "Case sensitivity: LogLevel Information legacy from command line.")]
     public void TestEngineStartUpWithVerboseAndLogLevelOptions(string logLevelOption)
     {
         _fileSystem!.File.WriteAllText(TEST_RUNTIME_CONFIG_FILE, INITIAL_CONFIG);
@@ -850,7 +852,7 @@ public void TestEngineStartUpWithVerboseAndLogLevelOptions(string logLevelOption
     }
 
     /// <summary>
-    /// Test to validate that the engine starts successfully when --LogLevel is set to Warning
+    /// Test to validate that the engine starts successfully when --log-level is set to Warning
     /// or above. At these levels, CLI phase messages (logged at Information) are suppressed,
     /// so no stdout output with message 'info' is expected during the CLI phase.
     /// </summary>
@@ -871,7 +873,7 @@ public async Task TestEngineStartUpWithHighLogLevelOptions(string logLevelOption
         StringWriter consoleOutput = new();
         Console.SetOut(consoleOutput);
 
-        string[] args = { "start", "--config", TEST_RUNTIME_CONFIG_FILE, "--LogLevel", logLevelOption };
+        string[] args = { "start", "--config", TEST_RUNTIME_CONFIG_FILE, "--log-level", logLevelOption };
         _fileSystem!.File.WriteAllText(TEST_RUNTIME_CONFIG_FILE, INITIAL_CONFIG);
 
         // Run Program.Execute on a background task because StartEngine blocks until the host shuts down.
@@ -886,7 +888,7 @@ public async Task TestEngineStartUpWithHighLogLevelOptions(string logLevelOption
     }
 
     /// <summary>
-    /// Test to validate that the engine starts successfully when --LogLevel is set to None.
+    /// Test to validate that the engine starts successfully when --log-level is set to None.
     /// At these levels, CLI phase messages (logged at Information) are suppressed,
     /// so no stdout output is expected during the CLI phase.
     /// </summary>
@@ -901,7 +903,7 @@ public async Task TestEngineStartUpWithLogLevelNone(string logLevelOption)
         StringWriter consoleOutput = new();
         Console.SetOut(consoleOutput);
 
-        string[] args = { "start", "--config", TEST_RUNTIME_CONFIG_FILE, "--LogLevel", logLevelOption };
+        string[] args = { "start", "--config", TEST_RUNTIME_CONFIG_FILE, "--log-level", logLevelOption };
         _fileSystem!.File.WriteAllText(TEST_RUNTIME_CONFIG_FILE, INITIAL_CONFIG);
 
         // Run Program.Execute on a background task because StartEngine blocks until the host shuts down.
@@ -915,12 +917,12 @@ public async Task TestEngineStartUpWithLogLevelNone(string logLevelOption)
     }
 
     /// Validates that `dab start` correctly sets <see cref="Startup.IsCliOverriding"/>
-    /// based on whether the --LogLevel CLI flag is provided.
+    /// based on whether the --log-level CLI flag is provided.
     ///
-    /// When the --LogLevel flag is provided, IsCliOverriding should be true.
-    /// When the --LogLevel flag is omitted (log level comes from the config file), IsCliOverriding should be false.
+    /// When the --log-level flag is provided, IsCliOverriding should be true.
+    /// When the --log-level flag is omitted (log level comes from the config file), IsCliOverriding should be false.
     /// </summary>
-    /// <param name="cliLogLevel">The --LogLevel CLI flag value, or null to omit the flag.</param>
+    /// <param name="cliLogLevel">The --log-level CLI flag value, or null to omit the flag.</param>
     /// <param name="expectedIsOverridden">Expected value of Startup.IsCliOverriding.</param>
     [DataTestMethod]
     [DataRow(null, false, DisplayName = "IsCliOverriding is false")]
@@ -978,6 +980,7 @@ public async Task TestStartCommandResolvesLogLevelFromConfigOrFlag(
             isHttpsRedirectionDisabled: false,
             mcpStdio: false,
             mcpRole: null,
+            logLevelLegacy: null,
             config: TEST_RUNTIME_CONFIG_FILE);
 
         // Run TryStartEngineWithOptions on a background task because StartEngine blocks until the host shuts down.

src/Cli/Commands/StartOptions.cs

@@ -21,11 +21,12 @@ public class StartOptions : Options
 
         public LogBuffer CliBuffer { get; }
 
-        public StartOptions(bool verbose, LogLevel? logLevel, bool isHttpsRedirectionDisabled, bool mcpStdio, string? mcpRole, string config)
+        public StartOptions(bool verbose, LogLevel? logLevel, bool isHttpsRedirectionDisabled, bool mcpStdio, string? mcpRole, LogLevel? logLevelLegacy, string config)
             : base(config)
         {
             // When verbose is true we set LogLevel to information.
             LogLevel = verbose is true ? Microsoft.Extensions.Logging.LogLevel.Information : logLevel;
+            LogLevelLegacy = logLevelLegacy;
             IsHttpsRedirectionDisabled = isHttpsRedirectionDisabled;
             McpStdio = mcpStdio;
             McpRole = mcpRole;
@@ -37,7 +38,7 @@ public StartOptions(bool verbose, LogLevel? logLevel, bool isHttpsRedirectionDis
         [Option("verbose", SetName = "verbose", Required = false, HelpText = "Specifies logging level as informational.")]
         public bool Verbose { get; }
 
-        [Option("LogLevel", SetName = "LogLevel", Required = false, HelpText = LOGLEVEL_HELPTEXT)]
+        [Option("log-level", SetName = "loglevel", Required = false, HelpText = LOGLEVEL_HELPTEXT)]
         public LogLevel? LogLevel { get; }
 
         [Option("no-https-redirect", Required = false, HelpText = "Disables automatic https redirects.")]
@@ -49,6 +50,9 @@ public StartOptions(bool verbose, LogLevel? logLevel, bool isHttpsRedirectionDis
         [Value(0, MetaName = "role", Required = false, HelpText = "Optional MCP permissions role, e.g. role:anonymous. If omitted, defaults to anonymous.")]
         public string? McpRole { get; }
 
+        [Option("LogLevel", SetName = "LogLevel", Required = false, HelpText = LOGLEVEL_HELPTEXT, Hidden = true)]
+        public LogLevel? LogLevelLegacy { get; }
+
         public int Handler(ILogger logger, FileSystemRuntimeConfigLoader loader, IFileSystem fileSystem)
         {
             CliBuffer.BufferLog(Microsoft.Extensions.Logging.LogLevel.Information, $"{PRODUCT_NAME} {ProductInfo.GetProductVersion()}");

src/Cli/ConfigGenerator.cs

@@ -3066,10 +3066,10 @@ public static bool TryStartEngineWithOptions(StartOptions options, FileSystemRun
             List<string> args = new()
             { "--ConfigFileName", runtimeConfigFile };
 
-            /// Add arguments for LogLevel. Only pass --LogLevel when user explicitly specified it,
+            /// Add arguments for LogLevel. Only pass --log-level when user explicitly specified it,
             /// so that MCP logging/setLevel can still adjust the level when no CLI override is present.
             /// 
-            /// When --LogLevel is NOT specified:
+            /// When --log-level is NOT specified:
             /// - MCP stdio mode: Service defaults to None for clean stdout output
             /// - Non-MCP mode: Service defaults to Debug (Development) or Error (Production) based on config
             LogLevel minimumLogLevel;
@@ -3079,19 +3079,30 @@ public static bool TryStartEngineWithOptions(StartOptions options, FileSystemRun
             Utils.IsConfigOverriding = false;
             Utils.ConfigLogLevel = LogLevel.Information;
 
+            LogLevel? logLevel = null;
             if (options.LogLevel is not null)
             {
-                if (options.LogLevel is < LogLevel.Trace or > LogLevel.None)
+                logLevel = options.LogLevel;
+            }
+            else if (options.LogLevelLegacy is not null)
+            {
+                options.CliBuffer.BufferLog(LogLevel.Warning, $"--LogLevel is deprecated, please use --log-level instead.");
+                logLevel = options.LogLevelLegacy;
+            }
+
+            if (logLevel is not null)
+            {
+                if (logLevel is < LogLevel.Trace or > LogLevel.None)
                 {
                     options.CliBuffer.BufferLog(LogLevel.Error,
-                        $"LogLevel's valid range is 0 to 6, your value: {options.LogLevel}, see: https://learn.microsoft.com/dotnet/api/microsoft.extensions.logging.loglevel");
+                        $"LogLevel's valid range is 0 to 6, your value: {logLevel}, see: https://learn.microsoft.com/dotnet/api/microsoft.extensions.logging.loglevel");
                     return false;
                 }
 
-                minimumLogLevel = (LogLevel)options.LogLevel;
-                // Only add --LogLevel when user explicitly specified it via CLI.
+                minimumLogLevel = (LogLevel)logLevel;
+                // Only add --log-level when user explicitly specified it via CLI.
                 // This allows MCP logging/setLevel to work when no CLI override is present.
-                args.Add("--LogLevel");
+                args.Add("--log-level");
                 args.Add(minimumLogLevel.ToString());
             }
             else
@@ -3100,7 +3111,7 @@ public static bool TryStartEngineWithOptions(StartOptions options, FileSystemRun
 
                 // Track whether config explicitly set a log level. In MCP stdio mode this
                 // allows CLI logs to be emitted to stderr (instead of being suppressed)
-                // when the user expressed intent via the config file rather than --LogLevel.
+                // when the user expressed intent via the config file rather than --log-level.
                 if (deserializedRuntimeConfig.HasExplicitLogLevel())
                 {
                     Utils.IsConfigOverriding = true;

src/Cli/CustomLoggerProvider.cs

@@ -28,9 +28,9 @@ public class CustomConsoleLogger : ILogger
         private readonly LogLevel _minimumLogLevel;
 
         // Minimum LogLevel for CLI output.
-        // For MCP mode: prefer CLI's --LogLevel, fall back to config's log-level, otherwise suppress all.
+        // For MCP mode: prefer CLI's --log-level, fall back to config's log-level, otherwise suppress all.
         // For non-MCP mode: always use the level passed to the constructor.
-        // Note: --LogLevel is meant for the ENGINE's log level, not CLI's output.
+        // Note: --log-level is meant for the ENGINE's log level, not CLI's output.
         public CustomConsoleLogger(LogLevel minimumLogLevel = LogLevel.Information)
         {
             _minimumLogLevel = Cli.Utils.IsMcpStdioMode
@@ -93,13 +93,13 @@ public CustomConsoleLogger(LogLevel minimumLogLevel = LogLevel.Information)
         /// <summary>
         /// Creates Log message by setting console message color based on LogLevel.
         /// In MCP stdio mode:
-        /// - If user explicitly set --LogLevel (CLI) or log-level (config): write to stderr (colored output)
+        /// - If user explicitly set --log-level (CLI) or log-level (config): write to stderr (colored output)
         /// - Otherwise: suppress entirely to keep stdout clean for JSON-RPC protocol.
         /// </summary>
         public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
         {
             // In MCP stdio mode, only output logs if user explicitly requested a log level
-            // via either the CLI --LogLevel flag or the runtime config file's log-level.
+            // via either the CLI --log-level flag or the runtime config file's log-level.
             // In that case, write to stderr to keep stdout clean for JSON-RPC.
             if (Cli.Utils.IsMcpStdioMode)
             {

src/Cli/Exporter.cs

@@ -116,7 +116,8 @@ private static async Task ExportGraphQL(
                     isHttpsRedirectionDisabled: false,
                     config: options.Config!,
                     mcpStdio: false,
-                    mcpRole: null);
+                    mcpRole: null,
+                    logLevelLegacy: null);
 
                 Task dabService = Task.Run(() =>
                 {

src/Cli/Program.cs

@@ -60,7 +60,7 @@ private static void ParseEarlyFlags(string[] args)
                 {
                     Utils.IsMcpStdioMode = true;
                 }
-                else if (string.Equals(arg, "--LogLevel", StringComparison.OrdinalIgnoreCase) && i + 1 < args.Length)
+                else if (string.Equals(arg, "--log-level", StringComparison.OrdinalIgnoreCase) && i + 1 < args.Length)
                 {
                     Utils.IsCliOverriding = true;
                     if (Enum.TryParse<LogLevel>(args[i + 1], ignoreCase: true, out LogLevel cliLogLevel))

src/Cli/Utils.cs

@@ -29,21 +29,21 @@ public class Utils
         public static bool IsMcpStdioMode { get; set; }
 
         /// <summary>
-        /// When true, the CLI is the source overriding the log level (i.e., <c>--LogLevel</c> was supplied).
+        /// When true, the CLI is the source overriding the log level (i.e., <c>--log-level</c> was supplied).
         /// This allows logs to be written to stderr instead of being completely suppressed.
         /// </summary>
         public static bool IsCliOverriding { get; set; }
 
         /// <summary>
-        /// The log level specified via CLI --LogLevel flag.
+        /// The log level specified via CLI --log-level flag.
         /// Only valid when IsCliOverriding is true.
         /// </summary>
         public static LogLevel CliLogLevel { get; set; } = LogLevel.Information;
 
         /// <summary>
         /// When true, the runtime config is the source overriding the log level
         /// (i.e., <c>runtime.telemetry.log-level</c> was explicitly set).
-        /// This allows CLI logs to be written to stderr in MCP mode even when no --LogLevel flag was provided.
+        /// This allows CLI logs to be written to stderr in MCP mode even when no --log-level flag was provided.
         /// </summary>
         public static bool IsConfigOverriding { get; set; }
 

src/Core/Telemetry/ILogLevelController.cs

@@ -12,7 +12,7 @@ public interface ILogLevelController
     {
         /// <summary>
         /// Gets a value indicating whether the CLI is the source overriding the log level
-        /// (i.e., <c>--LogLevel</c> was supplied). When true, runtime-config (hot-reload)
+        /// (i.e., <c>--log-level</c> was supplied). When true, runtime-config (hot-reload)
         /// updates are ignored.
         /// </summary>
         bool IsCliOverriding { get; }
@@ -35,7 +35,7 @@ public interface ILogLevelController
         /// The MCP level string is mapped to the appropriate LogLevel.
         /// Log-level precedence (highest to lowest):
         /// 1. Agent (MCP <c>logging/setLevel</c>) — always wins.
-        /// 2. CLI <c>--LogLevel</c> flag.
+        /// 2. CLI <c>--log-level</c> flag.
         /// 3. Config <c>runtime.telemetry.log-level</c>.
         /// 4. Defaults.
         /// </summary>