fix: make spec version lookup translatable in test case generation

[admclamb]

Problem

Submitting a problem for validation failed for every setup with:

Test case generation failed for 2 setup(s): Unhandled error: The LINQ expression
'DbSet<TestCaseGenerationSpec>()
    .Where(s => s.ProblemSetupId == __locals1_request_ProblemSetupId)
    .Select(s => s.Version)
    .DefaultIfEmpty(0)' could not be translated.

EF Core can't translate a top-level DefaultIfEmpty over a scalar sequence, so computing the next TestCaseGenerationSpec version threw before any generation work ran. Nothing was wrong with the authored problem content — it hit on every setup, in both JS and Python.

Fix

Aggregate as a nullable int and coalesce in memory. SQL MAX over zero rows returns NULL, which maps to null and becomes 0 — same semantics, fully translatable.

int previousVersion =
    await db
        .Set<TestCaseGenerationSpec>()
        .Where(s => s.ProblemSetupId == request.ProblemSetupId)
        .MaxAsync(s => (int?)s.Version, cancellationToken) ?? 0;

Testing

dotnet build on StackDuel.Infrastructure succeeds (pre-existing CS8603 warnings in GameConfiguration.cs only). Test runs are blocked locally by Application Control, so this leans on CI.

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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