Add opt-in EmitShapeTag support

[sator-imaging]

Motivation

• Prevent accidental emission of the human-readable string ShapeTag by default because it can expose internal type details, while still providing ShapeHash for consumers and an opt-in escape hatch.

Description

• Injected the attribute to include an obsolete public bool EmitShapeTag; and an explicit parameterless constructor on the generated ZeroSerializerAttribute so consumers can opt in; changes in src/ZeroSerializerGenerator.cs.
• Added syntax-based detection ShouldEmitShapeTag that inspects attribute arguments and pipes the result into the TypeGenerationModel via a new EmitShapeTag property in src/TypeGenerationModel.cs.
• Made generated view output conditional: XML <remarks> and the active public const string ShapeTag are emitted only when EmitShapeTag is true, otherwise a commented-out ShapeTag line with guidance is emitted, while ShapeHash is always generated; changes in src/ZeroSerializerGenerator.cs.
• Opted existing test models into explicit emission where the tests rely on ShapeTag, and added a new unit test file tests/ShapeTagEmissionTests.cs that covers default suppression, explicit emission, and the injected attribute contents.

Testing

• Ran repository checks git diff --check and git diff --cached --check, which succeeded.
• Attempted to run the test suite with dotnet test tests/ZeroSerializer.Tests.csproj -f net8.0 --no-restore but the environment does not have dotnet installed so the command could not be executed.
• New unit tests were added (tests/ShapeTagEmissionTests.cs) and model fixtures were updated (tests/SerializationModels.cs), but the C# test run was not executed in this environment due to the missing dotnet tool.

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Codex Task

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Summary by CodeRabbit

• New Features

  • Added an opt-in setting to include shape tags and related metadata in generated serialization views.
  • Generated output now provides guidance comments when shape-tag emission is disabled.
  • Existing serialization models can enable shape-tag generation through their serializer configuration.

• Tests

  • Added coverage for default behavior, opt-in shape-tag output, remarks, and generated attribute metadata.

Walkthrough

The serializer generator now supports opt-in shape-tag emission through the obsolete EmitShapeTag attribute field. Generated views emit shape-tag documentation and constants only when the field is set to true. Tests cover both modes and injected metadata.

Changes

Shape tag emission

Layer / File(s)	Summary
Attribute capture and generation model src/ZeroSerializerGenerator.cs, src/TypeGenerationModel.cs	The injected attribute exposes the obsolete EmitShapeTag field and a parameterless constructor. The generator detects a literal EmitShapeTag = true argument and stores the setting in TypeGenerationModel.
Conditional generated output src/ZeroSerializerGenerator.cs	Generated views include shape-tag remarks and an active ShapeTag constant when enabled. Disabled output contains explanatory comments instead.
Fixture and generator validation tests/SerializationModels.cs, tests/ShapeTagEmissionTests.cs	Four serialization models enable shape-tag emission. Generator tests verify default output, enabled output, and injected attribute metadata.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant SerializerAttribute
  participant ZeroSerializerGenerator
  participant TypeGenerationModel
  participant GeneratedView

  SerializerAttribute->>ZeroSerializerGenerator: Read EmitShapeTag = true
  ZeroSerializerGenerator->>TypeGenerationModel: Store emitShapeTag
  ZeroSerializerGenerator->>GeneratedView: Emit ShapeTag remarks and constant

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the opt-in EmitShapeTag change.
Description check	✅ Passed	The description explains the motivation, implementation, tests, and known test limitation for EmitShapeTag support.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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• Commit unit tests in branch codex/add-emitshapetag-to-zeroserializerattribute

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch codex/add-emitshapetag-to-zeroserializerattribute

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@tests/ShapeTagEmissionTests.cs`:
- Around line 22-36: Strengthen the ShapeTag emission tests: in the default-mode
test, assert that an uncommented public ShapeTag declaration is absent, and in
ShapeTagAndRemarksAreEmittedWhenRequested, assert that the public ShapeHash
declaration is still present. Keep the existing assertions for commented
ShapeTag output and enabled remarks.

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Fix all unresolved CodeRabbit comments on this PR:

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 29f7f5a9-e159-4a56-8d24-5e78fdd11630

📥 Commits

Reviewing files that changed from the base of the PR and between 6b7c124 and ed755e8.

📒 Files selected for processing (4)

• src/TypeGenerationModel.cs
• src/ZeroSerializerGenerator.cs
• tests/SerializationModels.cs
• tests/ShapeTagEmissionTests.cs

📜 Review details

⏰ Context from checks skipped due to timeout. (2)

• GitHub Check: test (Debug)
• GitHub Check: test (Release)

🔇 Additional comments (4)

src/ZeroSerializerGenerator.cs (1)

114-117: LGTM!

Also applies to: 292-292, 373-407, 957-980

src/TypeGenerationModel.cs (1)

18-26: LGTM!

Also applies to: 39-40

tests/ShapeTagEmissionTests.cs (1)

39-71: LGTM!

tests/SerializationModels.cs (1)

25-25: 📐 Maintainability & Code Quality

No warning-policy issue found. The test project and repository configuration do not promote CS0618 warnings to errors. No narrow suppression is required.

			> Likely an incorrect or invalid review comment.