[SourceGeneration] Improve NodeSet to ModelDesign conversion and generated node state

[marcschier]

Summary

• Improves NodeSet to ModelDesign conversion for combined and multi-namespace NodeSets.
• Fixes generated method declarations, argument resolution, object type proxies, fluent builders, generated node state, shared generation helpers, and validation.
• Regenerates ISA95 NodeIds as generator output from these changes, not as a hand edit.

Stack context

This is PR 2 of a stacked split of integration PR #4093 into independently reviewable pieces. This PR is independent of the other stack PRs and contains no WoT content.

Validation

• dotnet build tests\Opc.Ua.SourceGeneration.Core.Tests\Opc.Ua.SourceGeneration.Core.Tests.csproj -c Release -p:CustomTestTarget=net10.0 -v:m
• dotnet test tests\Opc.Ua.SourceGeneration.Core.Tests\Opc.Ua.SourceGeneration.Core.Tests.csproj -c Release -p:CustomTestTarget=net10.0 --no-build
• dotnet build tests\Opc.Ua.SourceGeneration.Core.Tests\Opc.Ua.SourceGeneration.Core.Tests.csproj -c Release -p:CustomTestTarget=net48 -v:m
• dotnet test tests\Opc.Ua.SourceGeneration.Core.Tests\Opc.Ua.SourceGeneration.Core.Tests.csproj -c Release -p:CustomTestTarget=net48 --no-build
• dotnet build src\Opc.Ua.ISA95\Opc.Ua.ISA95.csproj -c Release -f net10.0 -v:m
• Confirmed ISA95 build leaves src\Opc.Ua.ISA95\Design\Common\Opc.ISA95.NodeIds.csv with no unstaged regeneration diff.

[Copilot]

Pull request overview

Note

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This PR improves OPC UA NodeSet → ModelDesign conversion and downstream code generation to better handle multi-namespace/combined NodeSets, method argument naming collisions, and correct runtime decoding/registration of generated nodes.

Changes:

• Added canonical C# identifier generation and improved string-literal escaping for generated code.
• Improved NodeSet import to better match ModelCompiler conventions (placeholder browse names, method declarations, DataTypeEncoding parenting).
• Updated generators (NodeState/ObjectType proxies/Fluent builders/NodeManager templates) to use stable method-argument symbol allocation and correct decoding contexts; added/expanded regression tests and fixtures.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
tools/Opc.Ua.SourceGeneration.Core/Shared/SourceGenerationUtils.cs	Adds ToCSharpIdentifier and improves literal escaping for generated code.
tools/Opc.Ua.SourceGeneration.Core/Schema/NodeSetToModelDesign.cs	Fixes placeholder symbolic-name mapping, method argument naming, method-type reuse, and DataTypeEncoding parenting.
tools/Opc.Ua.SourceGeneration.Core/Schema/ModelDesignValidator.cs	Ensures generated method-argument code names are assigned during import/validation.
tools/Opc.Ua.SourceGeneration.Core/Schema/ModelDesignExtensions.cs	Introduces scoped, collision-aware generated names for method arguments (non-serialized).
tools/Opc.Ua.SourceGeneration.Core/Generators/ObjectTypeProxyGenerator.cs	Uses scoped argument identifiers and correct message context for decoding structured outputs.
tools/Opc.Ua.SourceGeneration.Core/Generators/NodeStateGenerator.cs	Uses scoped argument identifiers, correct decoding context, and handles argument value materialization from model parameters.
tools/Opc.Ua.SourceGeneration.Core/Generators/NodeManagerTemplates.cs	Adds __FindByDataTypeId to support VariableFromDataTypeId(...) in fluent APIs.
tools/Opc.Ua.SourceGeneration.Core/Generators/MethodDesignArgumentResolver.cs	Refactors argument resolution and assigns generated argument names as a side effect.
tools/Opc.Ua.SourceGeneration.Core/Generators/FluentBuilderGenerator.cs	Adds pass-through VariableFromDataTypeId overloads and minor doc formatting.
tests/Opc.Ua.SourceGeneration.Core.Tests/Shared/SourceGenerationUtilsTests.cs	Adds unit tests for new identifier/literal escaping helpers.
tests/Opc.Ua.SourceGeneration.Core.Tests/Schema/NodeSetToModelDesignTests.cs	Adds regression test covering preservation of runtime argument names.
tests/Opc.Ua.SourceGeneration.Core.Tests/Schema/ModelDesignExtensionsTests.cs	Adds tests for scoped method-argument name allocation and serialization behavior.
tests/Opc.Ua.SourceGeneration.Core.Tests/Resources/SameNamespaceEncoding.NodeSet2.xml	Adds fixture covering DataTypeEncoding nodes with same-namespace ParentNodeId.
tests/Opc.Ua.SourceGeneration.Core.Tests/Resources/SameNamedMethodArguments.NodeSet2.xml	Adds fixture covering argument naming/pathological characters and collisions.
tests/Opc.Ua.SourceGeneration.Core.Tests/Resources/MethodArgumentNamespace.NodeSet2.xml	Adds fixture covering method-argument datatype namespace resolution at runtime.
tests/Opc.Ua.SourceGeneration.Core.Tests/Generators/ObjectTypeProxyGeneratorTests.cs	Adds regression test for structured output decode using session message context.
tests/Opc.Ua.SourceGeneration.Core.Tests/Generators/NodeStateGeneratorTests.cs	Adds generator-level regressions for encoding nodes and argument symbol stability.
tests/Opc.Ua.SourceGeneration.Core.Tests/Generators/FluentBuilderGeneratorTests.cs	Updates assertions to match new codegen behaviors and file names.
tests/Opc.Ua.SourceGeneration.Core.Tests/CompilerUtils.cs	Adds helpers to create in-memory AdditionalText and collect generator diagnostics.
src/Opc.Ua.ISA95/Design/Common/Opc.ISA95.NodeIds.csv	Regenerates NodeIds to reflect placeholder symbolic-name mapping changes.

[codecov]

Codecov Report

❌ Patch coverage is 92.94118% with 30 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.92%. Comparing base (8a10139) to head (2048f38).
⚠️ Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
...urceGeneration.Core/Schema/NodeSetToModelDesign.cs	67.64%	8 Missing and 3 partials ⚠️
...rceGeneration.Core/Schema/ModelDesignExtensions.cs	91.00%	1 Missing and 8 partials ⚠️
...rceGeneration.Core/Shared/SourceGenerationUtils.cs	88.09%	2 Missing and 3 partials ⚠️
...ceGeneration.Core/Generators/NodeStateGenerator.cs	96.25%	1 Missing and 2 partials ⚠️
...Ua.Server/NodeManager/NodeStateLookupExtensions.cs	75.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4132      +/-   ##
==========================================
- Coverage   80.23%   79.92%   -0.32%     
==========================================
  Files        1515     1524       +9     
  Lines      209980   210992    +1012     
  Branches    36213    36387     +174     
==========================================
+ Hits       168479   168627     +148     
- Misses      28867    29693     +826     
- Partials    12634    12672      +38     

Files with missing lines	Coverage Δ
src/Opc.Ua.Di.Server/DiNodeManager.cs	69.65% <100.00%> (+0.09%)	⬆️
src/Opc.Ua.Server/Fluent/FluentNodeManagerBase.cs	63.82% <100.00%> (+0.78%)	⬆️
src/Opc.Ua.Server/Fluent/NodeManagerBuilder.cs	90.07% <100.00%> (+2.03%)	⬆️
...neration.Core/Generators/FluentBuilderGenerator.cs	86.09% <100.00%> (+0.17%)	⬆️
...on.Core/Generators/MethodDesignArgumentResolver.cs	80.00% <100.00%> (+11.57%)	⬆️
...Generation.Core/Generators/NodeManagerTemplates.cs	100.00% <100.00%> (ø)
...ration.Core/Generators/ObjectTypeProxyGenerator.cs	84.79% <100.00%> (+1.06%)	⬆️
...urceGeneration.Core/Schema/ModelDesignValidator.cs	71.97% <100.00%> (+0.01%)	⬆️
...Ua.Server/NodeManager/NodeStateLookupExtensions.cs	92.30% <75.00%> (-7.70%)	⬇️
...ceGeneration.Core/Generators/NodeStateGenerator.cs	87.37% <96.25%> (-0.17%)	⬇️
... and 3 more

... and 59 files with indirect coverage changes

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[marcschier]

Fixed the net10.0 solution build failure on this PR.

The FluentBuilderGenerator in this change emits calls to
INodeManagerBuilder.VariableFromDataTypeId and to a NodeManagerBuilder constructor
overload carrying the data-type lookup, but the runtime side of that API was not part of
this PR - it had been grouped into a later server PR that does not exist yet. Every
generated node manager therefore failed to compile:

BoilerNodeManager.NodeManager.g.cs(97,31): CS1729: 'NodeManagerBuilder' does not
  contain a constructor that takes 7 arguments
BoilerNodeManager.FluentBuilders.g.cs(140,24): CS1061: 'INodeManagerBuilder' does not
  contain a definition for 'VariableFromDataTypeId'

A generator change and the API it emits against have to land together, so the builder
API now ships here: VariableFromDataTypeId on the interface and implementation, plus
NodeStateLookupExtensions.FindByDataType, which is the lookup it delegates to and
which has no other consumer. FindByDataType was sitting unused in #4147 and has been
removed there in the same pass.

Also brings the eight NodeManagerBuilderTests cases covering the new resolution:
unique match, null data type (BadNodeIdInvalid), no match (BadNodeIdUnknown),
ambiguous match (BadBrowseNameDuplicated), browse-name disambiguation, browse-name
miss, duplicate browse name, and a non-variable node (BadTypeMismatch).

Verified locally:

• MinimalBoilerServer and MinimalCalcServer both build clean - these are the two
  projects that were failing in CI.
• Opc.Ua.Server.Tests net10.0: 3841 passed, 0 failed.
• Opc.Ua.Server.Tests net48: 3840 passed, 1 failed - DurableDataValueQueueVerifyReferenceBatchingAsync,
  a known local file-lock flake unrelated to this change, verified passing in isolation.
• 0 warnings, 0 errors on both target frameworks.