DI Refactor: Azure.Mcp.Tools.Postgres

[Copilot]

Removes context.GetService<IPostgresService>() calls from ExecuteAsync across all Postgres commands, replacing them with constructor-injected dependencies.

Changes

• Commands — All 6 command classes now accept IPostgresService as a constructor parameter and use it via a private readonly field:

  • PostgresListCommand
  • DatabaseQueryCommand
  • ServerParamGetCommand
  • ServerParamSetCommand
  • ServerConfigGetCommand
  • TableSchemaGetCommand

• Tests — Updated all unit test constructors to pass the mock service directly to the command.

• PostgresSetup.cs — No changes required; DI container resolves IPostgresService automatically since commands are registered via AddSingleton<TCommand>().

Before / After

// Before
public sealed class ServerParamGetCommand(ILogger<ServerParamGetCommand> logger)
    : BaseServerCommand<ServerParamGetOptions>(logger)
{
    public override async Task<CommandResponse> ExecuteAsync(...)
    {
        IPostgresService pgService = context.GetService<IPostgresService>()
            ?? throw new InvalidOperationException("PostgreSQL service is not available.");
        ...
    }
}

// After
public sealed class ServerParamGetCommand(IPostgresService postgresService, ILogger<ServerParamGetCommand> logger)
    : BaseServerCommand<ServerParamGetOptions>(logger)
{
    private readonly IPostgresService _postgresService = postgresService;

    public override async Task<CommandResponse> ExecuteAsync(...)
    {
        var parameterValue = await _postgresService.GetServerParameterAsync(...);
        ...
    }
}

Invoking Livetests

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>DI Refactor: Azure.Mcp.Tools.Postgres</issue_title>
<issue_description>## Summary

Refactor Azure.Mcp.Tools.Postgres to use constructor dependency injection instead of resolving services via context.GetService<T>() in ExecuteAsync.

This is a sub-issue of #158.

Instructions

Follow the algorithm described in tools/di-refactor-plan.md with {ToolArea} = Postgres.

An example PR is: #1815
</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes DI Refactor: Azure.Mcp.Tools.Postgres #1865

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