Each activity category follows this layout:

{Category}/
├── {Category}.build.props                    # Version and metadata for this pack
├── UiPath.{Category}/                        # Core library (helpers, enums)
├── UiPath.{Category}.Activities/             # Activity classes (runtime logic)
│   ├── NetCore/ViewModels/                   # ViewModel classes (design-time UI)
│   ├── Properties/                           # .resx localization files
│   └── Resources/
│       ├── Icons/                            # SVG icons
│       └── ActivitiesMetadata.json           # Links activities ↔ ViewModels
├── UiPath.{Category}.Activities.Tests/       # xUnit tests
└── UiPath.{Category}.Activities.Packaging/   # NuGet package definition

Every activity has three parts: Activity (runtime logic) → ViewModel (design-time UI) → Metadata JSON (wiring and display). Property names on the ViewModel must exactly match the Activity’s property names.

# Build the full solution
dotnet build Activities/Community.Activities.sln

# Build a specific activity pack
dotnet build Activities/Activities.Cryptography.sln

# Run tests for an activity pack
dotnet test Activities/Activities.Cryptography.sln

# Build a NuGet package
dotnet build Activities/Cryptography/UiPath.Cryptography.Activities.Packaging/UiPath.Cryptography.Activities.Packaging.csproj

For in-depth guidance on activity code, ViewModels, widgets, rules, validation, metadata, localization, testing, and complete examples, see the Activity Development Guide.

• Minor version is increased every time a change in the public interface is made (e.g. a public property is added to an activity, a new activity is added)
• Major version is increased when the package suffers major changes (e.g. some activities become obsolete, the behaviour and the interface change)
• Any new property should specify a DefaultValue attribute. This will decrease the potential damage for forward compatibility
• Any obsolete property should specify the Obsolete attribute, Browsable(false) attribute and DesignerSerializationVisibilityAttribute if its value is no longer needed. Marking the property as obsolete should not change the behaviour for any of input provided.

(Inspired by https://github.com/dotnet/corefx/blob/master/Documentation/coding-guidelines/breaking-changes.md)

To help triage breaking changes, we classify them into three buckets:

1. Public Contract
2. Reasonable Grey Area
3. Unlikely Grey Area

Clear violation of public contract.

Examples:

• Throwing an exception in an existing common scenario where it previously was not thrown
• An exception is no longer thrown
• A different behavior is observed after the change for an input
• Renaming a public type, member, or parameter
• Decreasing the range of accepted values within a given parameter
• Changing the value of a public constant or enum member

Change of behavior that customers would have reasonably depended on.

Examples:

• Throwing a different exception type in an existing common scenario
• Change in timing/order of events (even when not specified in docs)
• Change in parsing of input and throwing new errors (even if parsing behavior is not specified in the docs)

These require judgment: how predictable, obvious, consistent was the behavior?

Change of behavior that customers could have depended on, but probably wouldn’t.

Examples:

• Correcting behavior in a subtle corner case

As with type 2 changes, these require judgment: what is reasonable and what’s not?

• All buckets (1, 2, and 3) breaking changes require talking to the repo owners first.
• If you’re not sure which bucket applies to a given change, contact us as well.
• It doesn’t matter if the old behavior is "wrong", we still need to think the implications through.
• If a change is deemed too breaking, we can help identify alternatives such as introducing a new API and deprecating the old one.