11.0.0-preview.1: retarget main to net11.0 / EF Core 11 / Npgsql 11 after the v10.0.0 tag, with the four behaviour changes as named tests #103

Scope since 2026-10-18: this is 11.0.0-preview.1, the retarget itself, under the 11.0.0 epic #147.

• On main, right after release/10.x is cut at the v10.0.0 tag (Tag-time branch steps assume a net11 branch that was never created #280), a PR carrying only: net11.0 in the four csproj files, EF 11 RC2 and Npgsql EF 11 RC references, #if around the two EF1001 usages if their shapes moved, PostgreSQL floor 16 in the docs.
• Public API identical to 10.0.0; the ApiCompat baseline is 10.0.0 and the pack must be clean.
• The four behaviour changes below become named tests, run in the integration suite against PostgreSQL 16 and 18 (CI matrix for two lines: .NET 10 and 11 SDKs, PostgreSQL floor and 18 legs per line #152).
• The release workflow publishes 11.0.0-preview.1 from main (prerelease path, --latest=false, Two supported lines: policy, branch rules, SECURITY rows, and the silent-fix rule as a minor with a changed-answers section #151); one preview per .NET 11 RC while the line is open.
• The consumer smoke test runs with the .NET 11 SDK, including the NativeAOT consumer.
• Core TFM on the 11 line: decide here. The Compile probe: C# 15 closed hierarchies and union types for the five variants, on net10.0 and net11.0 #148 probe showed closed needs no runtime support and a net11.0 consumer compiles fine against a net10.0 asset, so the core and NodaTime packages of the 11 line may keep net10.0 for reach, with only the two EF packages on net11.0. Trade-off: reach for .NET 10 consumers of the 11.x core (who could use 10.x anyway) versus one TFM per line and a simpler story. Recommendation: net11.0 on all four, one TFM per line, as every sampled EF plugin does; record the choice in the changelog's platform-floor line.

Raising the runtime floor of the released 10.x line is not on the table: 10.x stays on .NET 10 for its whole life.

Two couplings found on 2026-10-18 after #158/#159:

• ComplexIndexes. The integration project and the fourth smoke consumer reference EFCore.ComplexIndexes.PostgreSQL 5.4.0, which pins Npgsql.EntityFrameworkCore.PostgreSQL to [10.0.0, 11.0.0). On the 11 line that restore fails. So the retarget either waits for ComplexIndexes' 11.0.0-preview.1 (its issue Adopt the plain-docs voice and rewrite the consumer docs in it #38, which should go first) or conditions ComplexIndexesCrossTests and the fourth consumer on net10.0 with a comment naming Adopt the plain-docs voice and rewrite the consumer docs in it #38, and ComplexIndexes Support compiled models generated with --nativeaot #42 restores them on the 11 line. Prefer the first.

The four measured behaviour changes (original analysis, 2026-10-17)

EF Core 11 (11.0.0-rc.2.26504.105), .NET 11 RC2 and the Npgsql EF provider 11.0.0-rc.1.1 are published; EF 11 needs the .NET 11 runtime, so the move is a retarget, not a bump. A source diff of dotnet/efcore release/10.0 (a5e42cd) against release/11.0 (c8a9187, 2026-10-16) on the query and storage paths shows every interface this package implements unchanged: IRelationalParameterBasedSqlProcessorFactory, RelationalParameterBasedSqlProcessor.Process(Expression, ParametersCacheDecorator), IRelationalTypeMappingSourcePlugin, IMethodCallTranslatorPlugin, IMemberTranslatorPlugin, IAggregateMethodCallTranslatorPlugin, IQueryExpressionInterceptor, RelationalTypeMapping.Clone. The two EF1001 usages (PgBinaryExpression in ValueSetSqlGuard, PgNewArrayExpression in ValueSetsMethodCallTranslator) are Npgsql-internal, and the Npgsql 11 provider's notes list no query-tree changes; the NodaTime satellite's EF1001 pragmas are only the analyzer reading this package's own .Internal namespace.

Four things do change under the package and need a measured answer before 10.x targets EF 11 (none is a compile error):

1. JsonValueReaderWriter<T>.ToJson throws ArgumentNullException on null unless the new virtual HandlesNullWrites returns true. LiteralJsonValueReaderWriter<T> and the three YearMonth* writers override only ToJsonTyped. Whether EF 11 reaches ToJson with null for a nullable range or set property inside a ToJson() complex type (the "null and empty, kept apart" row in docs/efcore.md) must be tested; if it does, HandlesNullWrites and a null branch are the fix.
2. RuntimeConstantExpression (experimental, precompiled queries) is a new node that reduces to a ConstantExpression. RangeVariantConstantRetyper in ValueRangesQueryExpressionInterceptor relies on EF inlining Constant(value, Int32Range.Finite) and overrides VisitConstant. Whether the new node can carry a variant-typed range past the retyper is the one item that could change an answer; InlineRangeConstantTests and the integration suite decide it.
3. SqlExpressionFactory simplifies a == b ? null : a to NULLIF(a, b). ValueSetSqlGuard judges the final tree; a NULLIF over an array_cat-derived value is a new shape it has no arm for and must refuse (equality) rather than pass. Seed it.
4. Npgsql EF 11 raises the default PostgreSQL compatibility target from 14 to 16. Nothing this package emits is version-gated today; confirm timerange and multirange SQL are unaffected.

Also noted: EF 11 removes ITypeMappingSource.FindMapping(MemberInfo) and CoreTypeMapping.ValueGeneratorFactory (not used here), adds RelationalTypeMapping.GetDefaultProviderValue() (not overridden here; check whether the range and set mappings should), and Property(…) no longer configures primitive collections (value sets are not IEnumerable<T>, so inert). Npgsql 11 core is not on NuGet yet; its range, multirange, array and infinity behaviour is unverified.

Proposed: a CI job (allowed to fail until GA) that builds the four packages and runs the EF translation and integration suites against EF 11 RC + Npgsql EF 11 RC on net11.0, with the four items above as named tests; then the retarget PR for 10.x, with docs/migration.md saying what the consumer must do.

Sources: https://learn.microsoft.com/en-us/ef/core/what-is-new/ef-core-11.0/breaking-changes ; https://www.npgsql.org/efcore/release-notes/11.0.html ; https://npgsql.org/doc/release-notes/11.0.html ; https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-11/overview

Found by the platform-horizon review, 2026-10-17.