[Prognosticate X (Prognosticate-X)]

Motivation & Context

In .NET declarative workflows (Microsoft.Agents.AI.Workflows.Declarative), expressions and values were parsed using the host process's current culture (CultureInfo.CurrentCulture). On host systems configured with cultures where , is used as the decimal separator (such as de-DE or fr-FR):

1. PowerFx expressions like =Max(1, 2) failed to parse because , was treated as a decimal separator instead of an argument delimiter.
2. ObjectExtensions.ConvertType parsed strings like "3.14" using default culture, parsing "3.14" as 314 on de-DE or failing with FormatException on fr-FR.
3. Converting numbers back to string in ConvertType produced localized strings (e.g. "3,14").

Declarative workflows defined in YAML must produce identical, consistent behavior regardless of host locale, matching the behavior of the Python SDK package.

Fixes #10033

Description & Review Guide

• What are the major changes?

  • In WorkflowExpressionEngine.cs: explicitly set ParserOptions.Culture = CultureInfo.InvariantCulture when initializing the engine options so PowerFx parses formulas using invariant culture.
  • In TemplateExtensions.cs: pass ParserOptions with CultureInfo.InvariantCulture to engine.Eval(...).
  • In ObjectExtensions.cs: pass CultureInfo.InvariantCulture to int.Parse, long.Parse, decimal.Parse, double.Parse, DateTime.Parse, and TimeSpan.Parse. When converting IFormattable / DateTime / TimeSpan to string in ConvertToString, use CultureInfo.InvariantCulture.
  • Added unit tests in WorkflowExpressionEngineTests.cs, ObjectExtensionsTests.cs, and DeclarativeWorkflowTest.cs testing formula evaluation, type conversion, and declarative workflow execution under de-DE and fr-FR cultures.

• What is the impact of these changes?

  • Declarative workflows now parse formulas and convert numeric/temporal types identically across all cultures without breaking changes.

• What do you want reviewers to focus on?

  • Consistency of CultureInfo.InvariantCulture usage across PowerFx parser options and ConvertType.

Related Issue

Fixes #10033

AI Assistance

• No material AI assistance was used.
• This is an AI-assisted contribution. I reviewed, understood, and verified all submitted content and accept responsibility for it.

AI assistance details: Analysis of culture-dependent parsing paths and drafting unit tests for de-DE and fr-FR host locales.

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR links to an agreed issue with no competing open PR, or the Related Issue section documents a trivial-change or repository-automation exception.
• This is not a breaking change.

[Copilot]

🟡 Changes recommended

The invariant-culture fix lacks a regression test directly exercising RecalcEngine.Format under de-DE or fr-FR, so existing tests would still pass if the fix were removed.

1 open issue

• Add a culture-sensitive regression test for RecalcEngine.Format · New

What changed in this PR

This PR addresses #10033 by making .NET declarative workflow formula parsing and type conversions independent of the host culture.

Changes:

• Sets invariant culture for Power Fx parsing in the expression engine and template extension.
• Uses invariant culture for numeric and temporal parsing and formattable string conversion.
• Adds de-DE and fr-FR regression tests for expressions, conversions, and workflow execution.

File	Description
dotnet/​tests/​Microsoft.Agents.AI.Workflows.Declarative.UnitTests/​PowerFx/​WorkflowExpressionEngineTests.cs	Tests formula parsing under German and French cultures.
dotnet/​tests/​Microsoft.Agents.AI.Workflows.Declarative.UnitTests/​Extensions/​ObjectExtensionsTests.cs	Tests invariant numeric parsing and string conversion.
dotnet/​tests/​Microsoft.Agents.AI.Workflows.Declarative.UnitTests/​DeclarativeWorkflowTest.cs	Tests workflow execution and numeric state across cultures.
dotnet/​src/​Microsoft.Agents.AI.Workflows.Declarative/​PowerFx/​WorkflowExpressionEngine.cs	Configures invariant parsing while preserving side-effect settings.
dotnet/​src/​Microsoft.Agents.AI.Workflows.Declarative/​Extensions/​TemplateExtensions.cs	Passes invariant parser options to template evaluation.
dotnet/​src/​Microsoft.Agents.AI.Workflows.Declarative/​Extensions/​ObjectExtensions.cs	Makes supported parsing and formatting conversions culture-independent.

_{Review effort: Balanced}

[Prognosticate X (Prognosticate-X)]

Added regression tests in TemplateExtensionsTests.cs (both PowerFx and Extensions test suites) exercising RecalcEngine.Format with Max(1, 2) under de-DE and fr-FR host locales. Thanks for the review!