FieldWorks Managed NetFx Review

Compatibility Split

• Legacy product code is .NET Framework 4.8 and C# 7.3 unless a project explicitly targets modern .NET. The compiler will not always save you: check the project's LangVersion/target before writing modern syntax.
• New Avalonia modules may target net8.0-windows; do not leak C# 8+ syntax or net8-only APIs into net48 projects. Note that Src/Common/FwAvalonia/ itself is consumed from net48 hosts — verify a project's actual target rather than assuming Avalonia ⇒ net8.
• Legacy .csproj files require explicit source inclusion; SDK-style projects glob by default. A file added on disk is not necessarily in the build.
• SDK-style projects need an explicit <RootNamespace> for the Crowdin satellite-assembly build (see fieldworks-localization-review).

Required Checks

• User-visible strings use .resx patterns where product-facing.
• UI and async code marshals to the correct UI thread (via IUiScheduler in region code) and does not use sync-over-async.
• Disposable WinForms/GDI/LCModel/test resources are owned and disposed deterministically; region code follows the IDetailLifetime rules (idempotent disposal, late-callback suppression, event unsubscribe).
• Test discovery changes are validated across both net48 and net8 test assemblies.
• Use repo scripts for evidence: ./build.ps1 and ./test.ps1 — never bare dotnet build conclusions.

Review Red Flags

• Nullable annotations, records, file-scoped namespaces, switch expressions, or using var in net48/C# 7.3 projects.
• Broad project/test-runner changes justified only by one local test passing.
• Hardcoded Debug paths or absolute repo assumptions in tests.
• Skipped tests used as evidence of covered behavior.
• A new project added to disk but missing from FieldWorks.proj (traversal build) or FieldWorks.sln (IDE discovery).

Handoff

Report target frameworks touched, project-file implications, test commands/results, and any remaining compatibility risks.

Keep This Skill Current

When a new cross-target pitfall, project-file gotcha, or runtime difference bites a migration, add it here in the same PR; route durable lessons through ../fieldworks-winforms-to-avalonia-migration/references/lessons-learned.md.