Files
romanett 9b034f8291 Enable nullable reference types centrally; migrate all unset and annotations-only projects (#4700)
# Description

Nullable reference types are now enabled once, in `common.props`, and
every project in the repository builds warning-clean with them.

**Configuration**
- `<Nullable>enable</Nullable>` lives in `common.props`. All per-project
`<Nullable>` settings are removed: 178 project files (enable,
annotations, and the `disable` in the three Aot test projects).
- 419 per-file `#nullable enable`/`restore` directives and the 4
`#nullable disable` directives are removed.
- Kept on purpose:
- The 5 `<auto-generated>` schema files (`UANodeSet.cs`, `UA Type
Dictionary.cs`, `OPCBinarySchema.cs`, `SecuredApplication.cs`,
`PInvokeHelper.cs`) keep `#nullable enable`. The compiler ignores the
project setting in generated code, so the directive is required there.
- `tests/Opc.Ua.Interop.LegacyPeer` keeps `disable`. It builds against
the 1.5.378 packages and does not import the repository props.
- `docs/DeveloperGuide.md` and `.github/copilot-instructions.md` now
describe the central setting.

**Migration** (the 43 unset and 13 annotations-only projects, roughly
10k diagnostics)
- **Production code: annotated at the declarations.** Covers
`tools/Opc.Ua.SourceGeneration.Core`, `src/Opc.Ua.Lds.Server` and the
LDS sample.
- Members, parameters and returns are nullable where null actually
flows.
- Null-check helpers carry `[NotNullWhen]` (`IsNull`, `IsValidXmlName`,
`IsMethodTypeDesign`).
- `CoreUtils.Format`, `Utils.Format`, `ITemplateWriter.WriteLine` take
`params object?[]`. `Template.AddReplacement` takes `string?` (rendering
already skips null replacements).
- `IRegisteredServerStore.RegisterAsync` returns
`Task<RegistrationEntry?>`: it returns null when a registration is
removed.
- Dereferences backed by an invariant (for example, the validated model)
use `!`, so runtime behaviour is unchanged.
- **Behavioural changes in production code** (small, deliberate):
- `NodeSetToModelDesign` throws `InvalidOperationException` when the
file is not a NodeSet. Before, it threw a NullReferenceException on the
next line.
- `ModelDesignValidator` starts its lookup tables empty instead of null.
A redundant `if (m_nodes == null) return;` guard is gone.
- **Test code: minimal annotations.**
  - `?` on values that can be null, `!` where the test asserts non-null.
  - `= null!` for fixture members assigned in SetUp.
- `TryGetStructure<T>(out T? x)` where the inferred `T?` broke the
`IEncodeable` constraint.
- A few redundant `== null` checks on structs (`NodeId`, `ArrayOf<T>`)
folded into the adjacent `IsNull`/`Count` checks.

**Notes for reviewers**
- The diff is large (~1,500 files) but almost entirely mechanical: `?`,
`!` and directive removal. The non-annotation changes are listed above.
- Known follow-up, not done here:
`IModelDesign.Namespaces/TargetNamespace/NamespaceUris` stay
non-nullable even though the validator returns null before it loads a
dictionary. Making them nullable would ripple through every generator
call site.

## Related Issues

- Fixes #4439

## Checklist

- [ ] I have signed the
[CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf)
and read the
[CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md)
doc.
- [ ] I have added tests that prove my fix is effective or that my
feature works and increased code coverage.
- [x] I have added all necessary documentation.
- [x] I have verified that my changes do not introduce (new) build or
analyzer warnings.
- [ ] I ran **all** tests locally using the **UA.slnx** solution against
at least .net **framework** and .net **10**, and all passed.
- [ ] I fixed **all** failing and flaky tests in the CI pipelines and
**all** CodeQL warnings.
- [ ] I have addressed **all** PR feedback received.

The "no new warnings" box covers net10.0 and net48: full non-incremental
builds of `UA.slnx`, `tools/SourceGeneration.slnx`,
`tools/MigrationAnalyzer.slnx` and the Aot test projects finished with 0
warnings and 0 errors under the repository's warnings-as-errors
settings. net9.0 and net8.0 also had no nullable diagnostics, but they
were not rebuilt after the final fixes. Tests have not been run locally
yet.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-08 08:48:13 +02:00
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Vision samples

The Vision samples show OPC UA Vision in realistic production cells rather than as isolated image-processing calls.

Sample Role
VisualInspectionCell Server hosting Vision, AI Model Management, ISA-95 Job Control V2, and Alarms & Conditions for a machined-bracket inspection cell.
VisualInspectionAgent External deterministic orchestrator that connects with typed clients, measures fixture images, applies the recipe, routes jobs, and records operator ground truth.

The pair demonstrates a safety pattern that is deliberately stronger than "ask a model whether the part is good": the model path can produce measured characteristics and confidence, but deterministic recipe code owns the quality verdict. A photographed image therefore cannot become a free-form instruction to job control.

graph TD
    Agent["VisualInspectionAgent<br/>typed OPC UA clients"]
    Cell["VisualInspectionCell<br/>OPC UA server"]
    Vision["Vision<br/>sensor, clip endpoint, pipeline, results"]
    AI["AI Model Management<br/>deployment, Invoke, learning job"]
    ISA95["ISA-95 Job Control V2<br/>inspection and rework orders"]
    Alarms["Alarms & Conditions<br/>operator dialog"]

    Agent -->|"capture and submit results"| Vision
    Agent -->|"Invoke for provenance"| AI
    Agent -->|"StoreAndStart / transitions"| ISA95
    Agent -->|"respond to dialog"| Alarms
    Cell --> Vision
    Cell --> AI
    Cell --> ISA95
    Cell --> Alarms

Running the pair

Prerequisites: .NET 10 SDK.

Start the server:

dotnet run --project samples\Vision\VisualInspectionCell\VisualInspectionCell.csproj -- --insecure

Then run the orchestrator in the unattended deterministic mode:

dotnet run --project samples\Vision\VisualInspectionAgent\VisualInspectionAgent.csproj -- --server opc.tcp://localhost:62865/VisualInspectionCell --insecure --mode scripted --cycles 3

The server publishes static PNG fixture images. The agent retrieves a fixture, measures the bracket geometry, calls the AI deployment's Invoke path so model provenance and usage are visible in the address space, applies the recipe, and routes the ISA-95 order according to the deterministic verdict.

Use --mode live-ai --ai-endpoint <uri> only when a real model endpoint is configured. live-ai fails before creating any job when no endpoint is named; it never silently falls back to the deterministic analyser, because a sample that quietly degrades appears to work while demonstrating nothing.

See also