Conciseness

"Wildcard (`_`): Matches any value and discards it" and "Non-empty cases implicitly break (no `break` keyword required)" re-explain basic Dart semantics Claude already knows, and the map-pattern `containsKey` behavior is stated three times (Feedback Loop 2, the Nested JSON Validation example, and the checklist item). This goes beyond the 'minor instances of over-explanation' of level 4, fitting the mostly-efficient-but-could-be-tightened anchor.

Actionability

Concrete, complete, executable Dart code throughout: prefer/avoid pairs for each anti-pattern, a full `resolveAllowedAssetSubpath` function, a sealed-class `calculateArea` switch expression, and the specific verification command `dart analyze` with the exact compiler error text to look for. Examples cover the common cases; only trivial gaps exist (e.g. the omitted `math` import in the area example).

Workflow Clarity

An ordered 8-item implementation checklist is provided, plus two explicit feedback loops: static exhaustiveness checking (run `dart analyze`, review "The type 'X' is not exhaustively matched by the switch cases", then add missing Object patterns or a wildcard arm) and runtime Map/JSON semantics verification with omitted-key vs explicit-null guidance. This matches the checklist-plus-feedback-loops anchor at the top of the scale.

Progressive Disclosure

Internal structure is good: a linked contents section and well-scoped sections (selection strategy, syntax reference, anti-patterns, workflows, examples). However, the body twice references "examples/json_patterns.dart" as an executable implementation, and no such file exists in the bundle (no examples/, references/, scripts/, or assets/ directories are present), so the navigation pointer is broken — a minor organization gap that keeps it below the well-signaled-resolving-references level 5.

Specificity

Names the domain (Dart 3 pattern matching, switch expressions, destructuring) and multiple concrete actions: "validate data schemas, handle algebraic data types, and decompose control flow", destructuring Lists/Records/Maps/path segments, and "enforcing exhaustiveness on sealed classes". Coverage is comprehensive with no obvious gaps, matching the top anchor rather than the 'minor gaps' level 4.

Completeness

Explicitly answers "what" ("Applies Dart 3 pattern matching, switch expressions, and destructuring idiomatically to...") and "when" ("Use when refactoring complex if-else chains, parsing polymorphic JSON...") with concrete trigger phrases, plus negative triggers ("Don't use for simple boolean conditions, single-variable type promotion"). This clearly matches the both-what-and-when-with-concrete-triggers anchor.

Trigger Term Quality

"refactoring complex if-else chains", "parsing polymorphic JSON", "String.split() tokens", "URI/path segments", "sealed classes", and "Records" are exactly the natural phrases a Dart developer would say, including API-level synonyms. No common variant is obviously missing, so it fits the comprehensive-coverage anchor rather than level 4.

Distinctiveness Conflict Risk

Tightly scoped to Dart 3 pattern matching with distinct, domain-specific triggers (sealed classes, switch expressions, destructuring Records); the negative triggers further reduce misfires. Minimal conflict risk with other skills, matching the clear-niche anchor.