What problem does it solve? MSBuild item groups are a common source of build bugs: duplicate file warnings from SDK globbing, targets running more times than expected due to cross-product batching, and Include vs Update misuse that silently fails to modify items. This Skill provides canonical patterns from Microsoft.Common.CurrentVersion.targets to diagnose and correct these issues in .csproj files. ## Core Features & Use Cases - Include/Remove/Update Semantics: Clarifies when to add items, subtract items via set operations, or modify metadata on existing items without re-adding them. - Batching and Transforms: Explains %(Metadata) batching at target and task level, per-item filtering with Condition, and @(Item->'expression') transforms for path mapping. - Pitfall Remediation: Fixes cross-product batching (O(N×M) executions), CS2002 duplicate file warnings, missing FileWrites registration for clean support, and generated files polluting the source tree instead of IntermediateOutputPath. - Use Case: A target that zips outputs runs 12 times instead of 3 because it references %(Metadata) from two item groups; this Skill identifies the cross-product and rewrites it to batch on one group while reading the other as a property. ## Quick Start Ask the assistant to review your .csproj item groups for batching mistakes, duplicate globbing, or Include versus Update misuse and apply the canonical fixes.
