[matt-edmondson]

Fixes #50

What changed

• RequirementRuleCompiler.HasRules now claims a list, array or dictionary (anything assignable to IList or IDictionary) whose element or value type reaches a decorated member. Nested lists and dictionaries count too, so Dictionary<string, List<T>> and List<List<T>> are claimed. A collection that holds itself ends the search.
• Sets, stacks, queues and bare IEnumerable stay unclaimed, for the positional-pairing reasons given on GraphValidator.DescendList. If one were claimed, its elements would be materialized factory-free and then never walked. Unclaimed, each element is still validated on its own, as before.
• GraphValidator.Validate starts from Descend rather than Walk, so a root array or object-shaped dictionary is walked with [i] and key paths.

Claiming a collection only matters at the payload root. Below a claimed holder, the subtree is already materialized through factory-free options, so holders behave as before.

Call	Before	After
Deserialize<List<SimpleConfig>> on [A, B, A]	[Tuning]	[0].Tuning, [2].Tuning
Deserialize<SimpleConfig[]>	[Tuning]	[0].Tuning, [2].Tuning
Deserialize<Dictionary<string,SimpleConfig>>	[Tuning]	a.Tuning, b.Tuning

Side effect on System.Text.Json's own errors at a root collection

• Type errors ({"Mode":"oops"} in element 1) now get exactly the path and line System.Text.Json reports without the factory, $[1].Mode. Before this change the path was $[1], with the inner path kept in the inner exception. The three ErrorLocationTests that pinned the old shape now assert the paths match exactly.
• MaxDepth exceeded inside an element is now reported at $ on the same line, rather than at $[0]. A claimed root buffers its whole value through the caller's reader, and the depth limit fails during that buffering. A claimed root object already behaves this way.
  • I tried reading the root straight from the caller's reader to keep $[0].x. It doesn't help: System.Text.Json's own read-ahead (TrySkip) hits the limit first.
  • The test for the nested-element case now uses a root HashSet<T>, which still goes through a per-element converter, and a new test pins the $ root behaviour.

Tests

• New RootCollectionTests covers:
  • a root List<T>, T[], Dictionary<string,T> and List<List<T>>, each reporting every violation in one exception;
  • valid payloads, and a round trip;
  • which collections are claimed: sets, stacks, IEnumerable<T>, List<HashSet<T>>, collections of undecorated types and a self-listing type are not.
• Updated the two tests that pinned the exclusion: EligibilityTests.BareCollectionsAreStillNotClaimed, now BareCollectionsOfNotEmptyTypesAreClaimed, and RequirementRuleCompilerTests.HasRulesRejectsPrimitivesStringsAndEnums, which now uses List<int>.
• With the library change reverted, the 10 new or updated tests fail. With it applied, all 296 tests pass on net10.0.
• net8.0 and net9.0 were not run locally because those runtimes aren't installed here. CI runs them.
• The library builds cleanly for every target framework.

README "How it works" and CLAUDE.md "Reachability" now describe root collections.

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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