Epic: 11.0.0 #147

Goal

Open the .NET 11 line: net11.0, EF Core 11, Npgsql 11, PostgreSQL 16+. It ships as 11.0.0-preview.N from main once v10.0.0 is tagged (one preview per .NET 11 RC), and as 11.0.0 after .NET 11 GA. There is no preview branch (#280).

Decision (2026-10-18): two parallel lines, one per platform major, as EntglDb/BLite and EFCore.ComplexIndexes do. 10.x is the LTS line on .NET 10 (supported to 2028-11). 11.x is where the surface changes: the five range variants become C# 15 closed hierarchies or union types, which is the one change that justifies a separate major rather than a net11.0 TFM in the same package.

In scope and out of scope

In scope: the retarget, the compile probe and the rewrite of the variants, the native HasWithoutOverlaps/HasPeriod documentation, the two-line policy and release wiring, and the CI matrix with PostgreSQL floor legs.

Added 2026-10-19 (maintainer): #275, the per-domain range set types (Int32RangeSet, DateRangeSet, …) that replace RangeSet<TRange, T>. With #149 non-breaking, this is the breaking surface change the 11 line carries; 10.0.0 ships with "nothing removed or renamed" and the set family differs between the lines from then on.

Out of scope: the 14 silent fixes (#58) — they land on main first and are merged forward. The 10.0.0 features (#58: scheduling and parity themes, the Float32/Float64 family #153) — they land on main and are merged forward like the fixes. Later additions ship as 10.x minors within the window #178 sets. ltree — it belongs in the sibling hierarchies package, not here (research 2026-10-18: Npgsql's LTree is translation-only and its maintainers declined client-side semantics three times; no .NET package fills the gap; the domain is label paths, not intervals).

Sequence

1. At the v10.0.0 tag: cut release/10.x, then retarget main (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). Fixes for both go to main first and are cherry-picked with -x.
2. 11.0.0-preview.1 = pure retarget, identical public API.
3. 11.0.0-preview.2 = the unions marked closed (Mark the range unions closed (C# 15) for compile-time exhaustiveness, on both lines #149; closed not union, decided after the Compile probe: C# 15 closed hierarchies and union types for the five variants, on net10.0 and net11.0 #148 probe). Not platform-bound: it also ships on 10.x as a minor after .NET 11 GA, inside the additions window (10.x takes additions for six months after v11.0.0, not only until it #178), so the two lines are driven by EF Core 11 / Npgsql 11, not by the language feature.
4. 11.0.0-preview.3 = the per-domain range set types (Per-domain range set types (Int32RangeSet, DateRangeSet, …) replace RangeSet<TRange, T> #275) replacing RangeSet<TRange, T>; docs/migration.md v10.x gets the rename.

Done when

• every sub-issue is closed
• 11.0.0-preview.N has been published for each .NET 11 RC that was current while the line was open
• the root changelog opens 11.0.0 with the platform floor, the variants migration and the "what can break you" list, and docs/migration.md has a v10.x section
• v11.0.0 is tagged on main and the four packages are on NuGet
• release/10.x exists, CONTRIBUTING and SECURITY.md name both lines
• release/10.x carries the same branch protection as main (GitHub settings, done by hand; CONTRIBUTING promises it)