modern-go

# modern-go Modernize Go source code by applying version-appropriate idioms, APIs, and language features. Works like `go fix` plus additional transformations curated from the Go team's modernize analysis passes and community best practices. ## Usage Invoke this skill when the user asks to modernize Go code. By default, modernize the entire project; the user may specify a file or directory instead. When invoked: 1. Detect the project's Go version from `go.mod` (the `go` directive). 2. Find all `.go` files in the target scope (excluding `vendor/`, `.git/`, `testdata/`). 3. For each file, apply **all transformations for versions ≤ the project's Go version**, starting from the oldest to the newest. 4. After all transformations, print a summary of what was changed and what was skipped. If the user specifies a file or directory, limit the scope to that path. ## Transformation Catalog Each transformation includes a **Go version** gate—only apply when the project's `go.mod` version ≥ that version. Never apply a transformation that requires a version higher than the project declares. ### Go 1.0+ — `time.Since` | Before | After | |---|---| | `time.Now().Sub(start)` | `time.Since(start)` | ```go // before elapsed := time.Now().Sub(start) // after elapsed := time.Since(start) ``` ### Go 1.8+ — `time.Until` | Before | After | |---|---| | `deadline.Sub(time.Now())` | `time.Until(deadline)` | ```go // before remaining := deadline.Sub(time.Now()) // after remaining := time.Until...