[electricessence]

Ready to merge for 11.0.0-preview02. 948 of 948 tests in Release and Debug; 0 warnings and 0 errors on netstandard2.0, netstandard2.1 and net10.0; samples build and pass; merges cleanly with master.

What this adds: RowMap<T>

A validated, read-only mapping of a model's properties to differently named columns, built once from an ImmutableArray<KeyValuePair<string, string?>> and reused on every query. The type is small on purpose: one public constructor. The pairs are validated there (ArgumentException) and reduced to one column table; the compiled row readers are built lazily, per result-set layout, on the first query and cached inside the map.

static RowMap<Post> PostMap => field ??= new([new(nameof(Post.Id), "post_id"), new(nameof(Post.Body), null)]);

var posts = connection.Command("select * from posts").Map<Post>(PostMap).ToList();

• null as a column means "do not map this property"; properties the map does not mention still map by name (columns match ignoring case, property names exactly).
• One strict overload per method: RowMap<T>? map (before the CancellationToken) in Core, Channel and Dataflow. Removed: every IEnumerable<KeyValuePair>/pair overload, the inline params ImmutableArray overload, the content-keyed cache and string-key builder, public For, the lenient path. The value-tuple overloads remain as thin convenience wrappers that build a strict map per call (about 29 KB and a reader compile per call, against 464 B for a declared map), and say so in their docs.
• Reduced after review: no collection-expression builder, no implicit conversion, no enumeration, no RowMap builder class, no span round trip. Clean syntactic conveniences can be added later; the function stays the same.
• Instance-only property mapping (a static property used to pass validation and then fail on the first read). Version bumped to 11.0.0-preview02.

Review

A six-reviewer read-only swarm of the earlier head found two real defects, both fixed with tests (IExecuteReader.Results<T>() with no map threw; a bare null map was ambiguous for ResultsAsync<T>(command, null, ct)). A second six-reviewer swarm questioned the type itself; its unanimous cut list is applied here. Two first-use race tests no longer compare the racing instances' enumerations (the enumerator is gone); they still assert the rows each racer read.

Breaking changes (preview02)

IEnumerable<KeyValuePair> and params pair arguments to the mapping parameter (pass a RowMap<T>); the named argument fieldMappingOverrides: (the parameter is map); passing a RowMap<A> to a query for model B; tuple overloads now validate strictly and no longer share a cache. Full list in docsite/articles/whats-new-11.md.

Known, deliberately deferred

• No timing run after the reshaping; allocation figures were re-measured, timings in Benchmarks/RESULTS.md predate the final API.
• Open question for the maintainer: whether the compiled readers should hang off the array (identity-keyed) instead of a RowMap<T>; the reviewers' trade-offs are in the PR discussion.
• The cancellation-token change (a per-call token on every async terminal, UseCancellationToken kept as the default) is the next preview.

🤖 Generated with Claude Code