Introduce the new options pattern

[hallipr]

What does this PR do?

This pull request introduces significant refactoring to the Azure MCP command and options infrastructure, primarily to simplify option binding and validation, and to improve consistency across commands. The changes also include updates to retry policy configuration, test adjustments, and new project references.

• Removed SearchService's ConfigureRetryPolicy in favor of the common base class method

GitHub issue number?

[Link to the GitHub issue this PR addresses]

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[hallipr]

/azp run mcp - pullrequest - live

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Copilot]

Pull request overview

This PR introduces a new attribute-driven options binding pattern for MCP commands. Public properties on a typed TOptions POCO are reflected into System.CommandLine Option<T> instances via the new OptionBinder/OptionDescriptor/OptionAttribute/OptionNameConvention pieces, removing the need for hand-written RegisterOptions/BindOptions overrides per command. Alongside this, RetryPolicyOptions is reshaped so all values are nullable (with Has* flags now derived rather than stored), retry configuration is centralized in a ConfigureRetryOptions extension, and a new ISubscriptionResolver abstraction replaces direct calls to CommandHelper in commands that derive from a new SubscriptionCommand<,>/AuthenticatedCommand<,>/BaseCommand<,> hierarchy. The KeyValueLockSetCommand is migrated as the first concrete consumer of the new pattern.

Changes:

• New options-binding infrastructure (OptionAttribute, OptionDescriptor, OptionBinder, OptionNameConvention, BaseCommand<TOptions,TResult>, AuthenticatedCommand<,>, SubscriptionCommand<,>) and ISubscriptionResolver/SubscriptionResolver.
• RetryPolicyOptions switched to nullable scalars with derived Has* flags; BaseAzureService.ConfigureRetryPolicy, MonitorService, CosmosService, and SearchService updated; new RetryOptionsExtensions.ConfigureRetryOptions extension added.
• KeyValueLockSetCommand/KeyValueLockSetOptions migrated to the new pattern; tests/DI updated to register ISubscriptionResolver.

Show a summary per file

File	Description
core/Microsoft.Mcp.Core/src/Options/OptionAttribute.cs	New attribute declaring CLI option metadata on POCO properties.
core/Microsoft.Mcp.Core/src/Options/OptionDescriptor.cs	Reflects POCO properties (with nullability/nesting) into descriptor list.
core/Microsoft.Mcp.Core/src/Options/OptionBinder.cs	Registers Option<T> on commands and binds parse results back to instances.
core/Microsoft.Mcp.Core/src/Options/OptionNameConvention.cs	Kebab-case conversion for property→option names.
core/Microsoft.Mcp.Core/src/Options/RetryPolicyOptions.cs	Switched to nullable scalars; Has* are now derived properties.
core/Microsoft.Mcp.Core/src/Commands/GlobalCommand.cs	Updated retry binding to write only when value present.
core/Microsoft.Mcp.Core/src/Commands/BaseCommand`2.cs	New typed-options base command with binding/validation pipeline.
core/Microsoft.Mcp.Core/src/Commands/AuthenticatedCommand`2.cs	Authenticated typed-options base command with auth-aware error mapping.
core/Microsoft.Mcp.Core/src/Helpers/CommandHelper.cs	Adds GetSubscription(string?) overload reused by the resolver.
core/Azure.Mcp.Core/src/Services/Azure/Subscription/ISubscriptionResolver.cs	New abstraction over subscription resolution.
core/Azure.Mcp.Core/src/Services/Azure/Subscription/SubscriptionResolver.cs	Default implementation delegating to CommandHelper.
core/Azure.Mcp.Core/src/Commands/Subscription/SubscriptionCommand`2.cs	Adds subscription option resolution + validation for typed commands.
core/Azure.Mcp.Core/src/Options/ISubscriptionOption.cs	Marker interface used by SubscriptionCommand<,>.
core/Azure.Mcp.Core/src/Options/OptionDescriptions.cs	Description constants for shared global options.
core/Azure.Mcp.Core/src/Options/RetryOptionsExtensions.cs	ConfigureRetryOptions extension on ClientOptions.
core/Azure.Mcp.Core/src/Services/Azure/BaseAzureService.cs	Updated to use nullable retry pattern with clamping preserved.
core/Azure.Mcp.Core/tests/.../BaseAzureServiceTests.cs	Test data adjusted for nullable RetryPolicyOptions.
core/Azure.Mcp.Core/tests/.../BaseAzureServiceRetryLimitsTests.cs	Removed Has* flags from test fixtures.
core/Azure.Mcp.Core/tests/.../RetryPolicyOptionsTests.cs	Equality tests updated for nullable semantics.
core/Azure.Mcp.Core/tests/.../CommandFactoryHelpers.cs	Registers ISubscriptionResolver substitute in test DI.
servers/Azure.Mcp.Server/src/Program.cs	Registers SubscriptionResolver in DI.
tools/Azure.Mcp.Tools.AppConfig/src/AppConfigSetup.cs	Adds DI extensions namespace for new registrations.
tools/Azure.Mcp.Tools.AppConfig/src/Commands/KeyValue/Lock/KeyValueLockSetCommand.cs	Migrated to SubscriptionCommand<,> and typed-options pipeline.
tools/Azure.Mcp.Tools.AppConfig/src/Options/KeyValue/Lock/KeyValueLockSetOptions.cs	Rewritten to use [Option] attributes and nullable retry.
tools/Azure.Mcp.Tools.AppConfig/tests/.../KeyValueLockSetCommandTests.cs	Wires ISubscriptionResolver substitute into test services.
tools/Azure.Mcp.Tools.Cosmos/src/Services/CosmosService.cs	Uses nullable pattern for retry options.
tools/Azure.Mcp.Tools.Monitor/src/Services/MonitorService.cs	Replaces inline retry config with ConfigureRetryOptions.
tools/Azure.Mcp.Tools.Search/src/Services/SearchService.cs	Removes obsolete local retry helper.
tools/Azure.Mcp.Tools.Workbooks/tests/.../UpdateWorkbooksCommandTests.cs	Updates test assertion for nullable DelaySeconds.

Copilot's findings

• Files reviewed: 29/29 changed files
• Comments generated: 3

[jongio]

Clean refactoring of the options binding infrastructure. The attribute-driven pattern via OptionBinder/OptionDescriptor is a solid replacement for the manual RegisterOptions/BindOptions overrides, and the nullable RetryPolicyOptions simplification removes a lot of boilerplate.

A few things I noticed that existing reviewers haven't covered: