Choose Swift Language Tooling

Choose Swift Language Tooling

Route Swift tooling by the information the task needs. Resolve toolchain ownership before interpreting output.

Workflow

1. Inspect repository guidance, Package.swift, Xcode project markers, build configuration, generated sources, and existing tooling dependencies.
2. Resolve the active toolchain without changing it:
   • record command -v swift, command -v swiftc, and swift --version
   • record swiftly use --print-location when Swiftly is installed
   • record xcode-select -p, xcrun --find swiftc, and xcrun swiftc --version on macOS
   • label each command and artifact as Swiftly, Xcode, or another explicitly named toolchain
3. Choose one primary information model:
   • source-accurate syntax and rewriting: swift-syntax-tooling-workflow
   • compilation, diagnostics, AST, SIL, IR, modules, or driver jobs: swift-compiler-inspection-workflow
   • types, USRs, documentation, occurrences, or symbol relationships: swift-semantic-indexing-workflow
   • editor protocol, completion, navigation, refactoring, or language-service diagnosis: sourcekit-lsp-workflow
4. Resolve the project model:
   • SwiftPM package
   • Xcode project or workspace
   • compilation database
   • build server
   • loose source file with explicit compiler arguments
5. State why the selected surface answers the question and why the nearest alternative does not.
6. Hand build, test, package-plugin, macro-package, signing, simulator, or device execution to the owning Apple Dev or server-side workflow.

Toolchain Contract

• Treat Swiftly and Xcode as separate first-class Swift toolchain owners.
• Use Swiftly-resolved tools for cross-platform Swift.org packages, CLI work, explicit .swift-version selection, and toolchain-version matrices unless repository guidance selects Xcode.
• Use xcrun-resolved tools when the task depends on an Apple SDK, selected Xcode, Xcode build settings, or Xcode-bundled SourceKit behavior.
• Recognize that swiftly use xcode makes Swiftly proxy the currently selected Xcode toolchain; still record both the Swiftly selection and xcode-select result.
• Do not mix a compiler from one toolchain with sourcekitd, SourceKit-LSP, SDKs, plugins, or SwiftSyntax libraries from another and call the result valid.
• Do not change swiftly use, .swift-version, xcode-select, Xcode settings, or DEVELOPER_DIR merely to inspect state.

Output

Return:

1. Toolchain ownership: Swiftly, Xcode, or another named owner for every selected binary.
2. Information model: syntax, compiler artifact, semantic query, index, or LSP.
3. Project model: SwiftPM, Xcode, compilation database, build server, or loose file.
4. Selected workflow: one primary skill and any required handoff.
5. Evidence: versions, resolved paths, build settings, and freshness of generated modules or indexes.

Guardrails

• Do not use SwiftSyntax to claim inferred types or project-wide references.
• Do not parse unstable compiler dumps when a supported library or protocol answers the question.
• Do not use raw SourceKit when LSP or SourceKitten already supplies the required contract with acceptable fidelity.
• Do not treat SourceKitten as a replacement for SwiftSyntax, SourceKit-LSP, or the compiler.
• Do not diagnose semantic or LSP failures before checking compiler arguments and build-state freshness.

Read references/tool-selection-matrix.md for the detailed routing matrix and stability classes.