---
name: swift-modernization-cleanup-workflow
description: Run complete modernization and repair passes over existing Swift code, sequencing formatting, source inventory, file splitting, API cleanup, error handling cleanup, functional pipeline cleanup, concurrency cleanup, tests, docs handoffs, and validation.
license: Apache-2.0
metadata:
  owner: gaelic-ghost
  repo: socket
  category: swift-language
---

# Swift Modernization Cleanup Workflow

## Purpose

Modernize existing Swift code without leaving cleanup half-done.

This is the top-level shared Swift repair workflow for poor-quality implementations, drifted source trees, unclear APIs, imperative pipeline tangles, old concurrency patterns, broad files, and weak validation.

## Ownership

- Use this skill for shared Swift language cleanup.
- Use `apple-dev-skills` for Apple framework behavior, Xcode execution, project membership, UI previews, signing, simulators, devices, and Apple docs gates.
- Use `server-side-swift` for Vapor, Hummingbird, SwiftNIO service hosting, persistence, Docker, Fly.io, auth, observability, and deployment.

## Workflow

1. Inspect before changing:
   - `AGENTS.md`
   - README or CONTRIBUTING
   - `Package.swift`
   - `.swiftformat`
   - `.swiftlint.yml`
   - Xcode or XcodeGen files when present
   - CI workflows
   - existing validation commands
2. Establish the formatting baseline through `swift-format-style-workflow`.
3. Inventory cleanup targets:
   - oversized files
   - mixed responsibilities
   - unclear public or internal APIs
   - callback-heavy or nested async code
   - mutable shared state
   - imperative parser, loader, or transform pipelines
   - weak error shapes and log messages
   - duplicate helpers
   - stale TODO/FIXME comments
   - missing or weak tests around changed behavior
4. Plan coherent slices:
   - source organization
   - API shape and naming
   - functional data pipelines
   - concurrency boundaries
   - error and logging quality
   - tests
   - docs handoffs
5. Apply complete passes:
   - avoid tiny partial edits when adjacent cleanup is part of the same concern
   - split files when concern boundaries are real
   - remove duplicate paths and stale wrappers
   - keep behavior validation close to each slice
6. Format again after structural changes.
7. Validate serially with the narrowest useful commands.

## Modernization Defaults

- Prefer Swift concurrency over callback pyramids when the target platform and repository support it.
- Prefer value flow over hidden mutation.
- Prefer functional pipelines for transformation-heavy code.
- Prefer `swift-error-handling-style-workflow` for broad failure-shape cleanup, typed throws decisions, domain error modeling, Cocoa bridging, and diagnostics.
- Prefer typed domain models over dictionaries, strings, or loosely coupled tuples.
- Prefer small support files with one clear job.
- Prefer tests around behavior before and after risky cleanup.
- Prefer human-readable errors that explain what operation failed and what to inspect next.

## Output Shape

Return:

1. `Cleanup state`: the current risks and code smells.
2. `Slice plan`: ordered cleanup slices and why each belongs.
3. `Changes`: files and responsibilities changed.
4. `Handoffs`: Apple, server-side, docs, project, or deployment owners.
5. `Validation`: commands run, results, and manual gaps.

## Guardrails

- Do not start with broad rewrites before reading repo guidance and validation commands.
- Do not leave compatibility shims, duplicate code paths, or transitional wrappers unless Gale explicitly approves.
- Do not silently change public API compatibility or deployment behavior.
- Do not run multiple SwiftPM or Xcode build/test commands concurrently.
- Do not claim runtime behavior is validated when only formatting or static checks ran.