[Copilot]

Query precompilation throws Non-IQueryable first parameter for ThenInclude because interceptor generation expects exactly one source type argument. IIncludableQueryable<TEntity, TPreviousProperty> has two.

• Interceptor generation: Extract the first source type argument without requiring it to be the only argument.
• Regression coverage: Exercise reference and collection overloads, single and chained ThenInclude calls, and sync/async execution through generated-code compilation and execution. Add SQL Server baselines.

• Fixes Query precompiler throws Non-IQueryable first parameter for ThenInclude #39274

[Copilot]

🟢 Approval recommended

No unresolved review issues were identified.

No open issues 🎉

What changed in this PR

Fixes precompiled query generation for ThenInclude chains with multi-generic source types.

Changes:

• Supports multi-argument IIncludableQueryable sources.
• Adds comprehensive sync/async and chained ThenInclude regression tests.
• Adds SQL Server baselines and guidance.

File	Description
test/​EFCore.SqlServer.FunctionalTests/​Query/​AdHocPrecompiledQuerySqlServerTest.cs	Adds SQL Server baselines.
test/​EFCore.Relational.Specification.Tests/​Query/​AdHocPrecompiledQueryRelationalTestBase.cs	Adds ThenInclude regression coverage.
src/​EFCore.Design/​Query/​Internal/​PrecompiledQueryCodeGenerator.cs	Supports multi-generic ThenInclude sources.
.agents/​skills/​query-pipeline/​SKILL.md	Documents precompiled include-chain guidance.

_{Review effort: Lite}

[Copilot]

🟢 Approval recommended

No unresolved blocking issues were identified.

No open issues 🎉

_{Review effort: Lite}

[github-code-quality]

Code coverage overview

Languages: C#

C# / code-coverage

main 8ece311	copilot/fix-thenincl... b426c7a	+/-
76%	76%	0%

View coverage of the 10 most impacted files.

File	main 8ece311	copilot/fix-thenincl... b426c7a	+/-
src/EFCore.Sqli...ryRepository.cs	97%	91%	-6%
src/Shared/NonC...yInitializer.cs	12%	11%	-1%
src/EFCore.Abst...erExtensions.cs	100%	100%	0%
src/EFCore.Anal...icSuppressor.cs	96%	96%	0%
src/EFCore.Cosm...nsExtensions.cs	82%	82%	0%
src/EFCore.Desi...onExtensions.cs	100%	100%	0%
src/EFCore.Desi...viderFactory.cs	95%	95%	0%
src/EFCore.Desi...CSharpHelper.cs	96%	96%	0%
src/EFCore.Desi...seOperations.cs	98%	98%	0%
src/EFCore.Desi...ionGenerator.cs	100%	100%	0%

ℹ️ Calculations represent line coverage. Results may change as calculations are updated.

---

_{Updated October 31, 2026 01:04 UTC}

[Copilot]

🟢 Approval recommended

No active review issues remain, and the change includes targeted ThenInclude handling plus regression coverage for the affected scenarios.

No open issues 🎉

_{Review effort: Lite}