Runtime and Language Standard

AIC Standard

AIC uses modern .NET as its default engineering platform.

Use case	Standard
Production baseline	.NET 10 LTS
Production language	C# 14
Future / preview evaluation	.NET 11 preview, C# 15
Legacy compatibility	Only where required and documented
Desktop Windows	WPF on modern .NET
Cross-platform mobile or desktop	.NET MAUI where justified
Web API	ASP.NET Core on .NET 10
Data access	EF Core 10 unless another approach is justified

Mandatory Rules

• New production projects MUST target net10.0 unless an exception is approved.

• C# production language version MUST align with the target framework.

• Do not force LangVersion=latest in production repositories unless specifically approved.

• Preview SDKs MUST NOT be used in production build agents.

• .NET 11 and C# 15 MAY be used for spikes, prototypes, accelerators or approved non-production work.

• All repositories MUST include global.json.

• Build images MUST install only approved SDKs.

• Dockerfiles MUST use supported runtime and SDK images.

Target Framework Guidance

Use single-targeting unless there is a real compatibility reason to multi-target.

<TargetFramework>net10.0</TargetFramework>

Use multi-targeting only where necessary, for example a reusable library consumed by multiple supported applications:

<TargetFrameworks>net8.0;net10.0</TargetFrameworks>

Multi-targeting increases test effort, package complexity and compatibility risk. It requires an ADR.

Language Version Guidance

Default approach:

<LangVersion>14.0</LangVersion>

Avoid:

<LangVersion>latest</LangVersion>

latest can make builds change unexpectedly when developer machines or build agents update. Use a specific version unless the repository is explicitly a preview or language exploration project.

Required Project Properties

Production projects SHOULD define or inherit:

<PropertyGroup>
  <TargetFramework>net10.0</TargetFramework>
  <Nullable>enable</Nullable>
  <ImplicitUsings>enable</ImplicitUsings>
  <LangVersion>14.0</LangVersion>
  <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
  <AnalysisLevel>latest</AnalysisLevel>
  <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
  <ContinuousIntegrationBuild Condition="'$(CI)' == 'true'">true</ContinuousIntegrationBuild>
</PropertyGroup>

Runtime Upgrade Rules

Runtime upgrades require:

• review of Microsoft breaking changes

• update to SDK pin

• update to build image

• dependency compatibility check

• test run across all supported projects

• performance smoke test for sensitive services

• security scan

• ADR or upgrade record

• customer approval where contractually required

Legacy Rule

Legacy .NET Framework, .NET Core 3.1, .NET 5, .NET 6 and .NET 7 MUST NOT be used for greenfield delivery. Legacy systems may be maintained only with a documented containment, migration or customer-approved support plan.