♻️ Modernize concurrency, tests and service conventions + Claude Code setup

[olejnjak]

Changes

Concurrency & tests

• Migrate tests from XCTest to Swift Testing
• Add comprehensive test coverage for core localization logic
• Introduce a FileSystem protocol to decouple file I/O from tests
• Replace internal Combine usage with async/await and remove leftover Combine extensions

Service conventions

• Surface RequestError from SheetsAPIService using typed throws
• Rename service protocols and implementations to new convention (plain protocol name + Impl)
• Hide service implementations behind public factory functions
• Remove file header comments

Claude Code setup

• Add CLAUDE.md project guidance and code style / service convention rules
• Add project .claude/settings.json (permissions, sandbox rules, plugins) and .mcp.json with Xcode MCP server

Closes#43
Closes#19

[Copilot]

Pull request overview

Copilot reviewed 39 out of 39 changed files in this pull request and generated 1 comment.

Suppressed comments (3)

Sources/ACKLocalizationCore/ACKLocalization.swift:38

• run() only handles LocalizationError explicitly; RequestError (thrown by SheetsAPIService) and other errors fall into the generic catch and get printed to stdout without the existing formatting / missing-sheet-tab mapping. This is a behavior regression compared to the previous pipeline where request failures were surfaced as LocalizationError.

 } catch let error as LocalizationError {
displayError(error)
exit(1)
} catch {
print(error)

Tests/ACKLocalizationCoreTests/Mocks/FileSystemMock.swift:5

• createdDirectories is an array, but the doc comment says it is "keyed by path" (which would imply a dictionary). This is misleading for future test authors.
  Sources/ACKLocalizationCore/Services/SheetsAPIServiceImpl.swift:38
• Force-unwrapping the percent-encoded sheet name and the URL (addingPercentEncoding(...)!, urlComponents.url!) can crash the process on malformed input. Since this is user-supplied data (sheet/tab names), prefer failing with RequestError instead of crashing.

 let sheetName = sheetName ?? spreadsheet.sheets.first?.properties.title ?? ""
var urlComponents = URLComponents(string: "https://sheets.googleapis.com/v4/spreadsheets/" + spreadsheet.spreadsheetId + "/values/" + sheetName.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed)!)!
urlComponents.queryItems = [URLQueryItem(name: "valueRenderOption", value: "UNFORMATTED_VALUE")]
var request = URLRequest(url: urlComponents.url!)
credentials?.addToRequest(&request)

[Copilot]

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[IgorRosocha]

LGTM, thanks for taking your time @olejnjak! 🙌

[babacros]

🕵️ ✅