Fix AOT code generation type safety issues

[natemcmaster]

Summary

Fixes critical and high-severity bugs in the source generator that were identified during review of #582.

Issues Fixed

Bug 1: Value Type Constructor Parameters (Critical - CS0077)

Problem: Generated code used as operator with non-nullable value types:

var p0_0 = _services.GetService(typeof(int)) as int;  // CS0077 compiler error

Fix: Check service object for null, then use direct cast:

var service0_0 = _services.GetService(typeof(int));
if (service0_0 != null) return new T((int)service0_0!);

Impact: Any command with value type constructor parameters (int, bool, etc.) would fail to compile with CS0077.

Bug 2: Nullable Array RemainingArguments (High Severity)

Problem: Used fragile string comparison for type detection:

if (sp.RemainingArgumentsPropertyType == "string[]")  // Fails for "string[]?"

Fix: Use actual type analysis with IArrayTypeSymbol:

info.SpecialProperties.RemainingArgumentsIsArray = property.Type is IArrayTypeSymbol;

Impact: Properties like string[]? would use wrong code path, causing InvalidCastException at runtime.

Additional Fixes

• Added System.Linq using to generated code for ToArray() support
• Fixed CommandData property name to CommandInfo to match interface
• Organized Claude planning documents in .claude/plans/

Test Coverage

Added comprehensive tests demonstrating both bugs:

1. GeneratorBugReproduction/ - Compilation test project that demonstrates bugs would cause CS0077
2. GeneratedModelFactoryTests.cs - Unit tests for value type handling patterns
3. SpecialPropertiesMetadataTests.cs - Tests for array type conversion logic

All tests now pass ✅

[natemcmaster]

Hey @robertmclaws, mind taking a look at this when you have time? This fixes a few bugs that Claude helped me identify in the original AOT PR (#582). The main issues were:

1. Value type constructor parameters causing CS0077 compilation errors
2. Nullable array types for RemainingArguments using wrong conversion logic

Both are now fixed with test coverage.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.93%. Comparing base (f0be726) to head (0fe1352).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #583   +/-   ##
=======================================
  Coverage   79.93%   79.93%           
=======================================
  Files         120      120           
  Lines        4017     4017           
  Branches      872      872           
=======================================
  Hits         3211     3211           
  Misses        618      618           
  Partials      188      188           

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[natemcmaster]

@claude can you review this PR?

[claude]

Claude finished @natemcmaster's task in 1m 36s —— View job

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Code Review Complete

I've reviewed this PR and the fixes look excellent! Both bugs are properly addressed with good test coverage. Here's my detailed analysis:

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Bug Fixes - Well Done ✅

Bug 1: Value Type Constructor Parameters (CRITICAL)

Problem identified correctly: The as operator cannot be used with non-nullable value types - this would cause CS0077 compiler error for any command with int, bool, etc. constructor parameters.

Fix is correct: The new pattern:

var service0_0 = _services.GetService(typeof(int));
if (service0_0 != null) return new T((int)service0_0!);

This properly checks the service object for null, then uses a direct cast. The fix at CommandMetadataGenerator.cs:1317 is the right approach.

Bug 2: Nullable Array RemainingArguments (HIGH SEVERITY)

Problem identified correctly: String comparison sp.RemainingArgumentsPropertyType == "string[]" fails for string[]? (and would also fail for other array variations like string?[]).

Fix is correct: Using property.Type is IArrayTypeSymbol (line 194) is the robust solution - it properly detects array types regardless of nullable annotations.

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Test Coverage - Comprehensive ✅

GeneratedModelFactoryTests.cs:

• Excellent documentation of the bug in comments (lines 68-100)
• Tests demonstrate correct pattern for value types
• Tests cover both all-value-types and mixed reference/value scenarios
• Edge cases covered (missing services, partial services)

SpecialPropertiesMetadataTests.cs:

• Tests array conversion from IReadOnlyList → string[] (lines 153-175)
• Tests direct cast for non-array collection types (lines 197-215)
• Tests nullable element arrays string?[] (lines 217-236)

GeneratorBugReproduction/ project:

• Real compilation test that would fail without fixes
• Good use of comments documenting what each bug demonstrates
• PublishAot=true ensures generator runs

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Code Quality Review

Strengths:

• Clear, well-commented code explaining the reasoning
• Proper use of Roslyn APIs (IArrayTypeSymbol instead of string comparison)
• Good variable naming (service0_0 clearly indicates intermediate variable)
• Added System.Linq using for ToArray() support (line 828)

Minor observations:

1. Property name fix (line 1049): Changed CommandData → CommandInfo to match interface. Good catch! ✅

2. Generated code pattern (lines 1314-1327): The two-step pattern is clear and correct:

   var service0_0 = _services.GetService(typeof(int));      // Step 1: Get service
   if (service0_0 != null && ...)                           // Step 2: Check nulls
       return new T((int)service0_0!);                      // Step 3: Cast & create

3. Array detection logic (line 194): The check property.Type is IArrayTypeSymbol is the right abstraction level - catches all array types including nullable variations.

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Potential Issues - None Found ✅

I don't see any bugs or issues with this PR. The fixes are:

• Correct and complete
• Well-tested
• Following best practices
• Properly documented

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Documentation & Organization

• .claude/plans/aot-plan.md moved to organized location ✅
• CLAUDE.md updated with build requirements - good addition for future contributors ✅
• Test documentation is clear and helpful ✅

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Summary

This is a high-quality fix for two critical bugs in the source generator:

• Bug 1 would cause compilation failures (CS0077)
• Bug 2 would cause runtime crashes (InvalidCastException)

Both are now fixed with proper Roslyn symbol analysis instead of fragile string comparisons. The test coverage is excellent and demonstrates the bugs would actually occur without the fixes.

Recommendation: Approve and merge ✅

The code quality is excellent, the fixes are correct, and the test coverage gives confidence these bugs won't regress.

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[robertmclaws]

I think it looks good too. Good catch on that cast, that would have been a pain.

[natemcmaster]

We can thank Claude for the catch. I didn't spot it either.