# spm-build-analysis

Analyzes Swift Package Manager dependencies, build plugins, and Xcode module graphs. It helps developers track down bottlenecks in clean and incremental build times.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 3400 installs · ★ 1264
- Author: AvdLee
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/AvdLee/Xcode-Build-Optimization-Agent-Skill/tree/HEAD/skills/spm-build-analysis/SKILL.md
- Updated: 2026-09-14
- HTML: https://affpapa.org/en/nevibecode/skills/spm-build-analysis

## What it does

This skill audits Swift Package Manager dependencies and module graph structure in Xcode. It inspects `Package.swift`, `Package.resolved`, binary target footprints, and build plugins. The agent treats analysis as evidence gathering first. It will never rewrite manifests or dependency sources without explicit confirmation.

Before suggesting package changes, the skill confirms that local packages in `Vendor/` are actually linked in `project.pbxproj` via `XCLocalSwiftPackageReference` and `XCSwiftPackageProductDependency`. For branch-tracked dependencies, it runs `python3 scripts/check_spm_pins.py --project App.xcodeproj`. The script checks remote tags and recommends pinning specific commit hashes when tags do not exist.

Migrating to a modular multi-target SDK does not automatically reduce build times. It often increases task count. Splitting an umbrella library multiplies `SwiftCompile`, `SwiftEmitModule`, and `ScanDependencies` tasks. The modular setup only pays off when your app skips compiling unused targets. If the build issue stems from project settings, the agent hands off the task to `xcode-project-analyzer`.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add AvdLee/Xcode-Build-Optimization-Agent-Skill --skill spm-build-analysis -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/spm-build-analysis/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/spm-build-analysis/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add AvdLee/Xcode-Build-Optimization-Agent-Skill --skill spm-build-analysis -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/spm-build-analysis/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add AvdLee/Xcode-Build-Optimization-Agent-Skill --skill spm-build-analysis -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/spm-build-analysis/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install AvdLee/Xcode-Build-Optimization-Agent-Skill spm-build-analysis
```

2. **Manually: put the files in place**
- File: `.github/skills/spm-build-analysis/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add AvdLee/Xcode-Build-Optimization-Agent-Skill --skill spm-build-analysis -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/AvdLee/Xcode-Build-Optimization-Agent-Skill --path skills/spm-build-analysis
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/spm-build-analysis/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add AvdLee/Xcode-Build-Optimization-Agent-Skill --skill spm-build-analysis -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/AvdLee/Xcode-Build-Optimization-Agent-Skill/tree/HEAD/skills/spm-build-analysis/SKILL.md

## When to use it
- detect circular dependencies and layering violations across SPM modules
- pinpoint build cascades triggered by heavy Swift macro expansion
- inspect branch-pinned dependencies and find tags for version pinning
- find oversized modules with over 200 files that hurt incremental builds
- catch duplicate package compilation caused by multi-platform targets

## Example prompts
- Analyze our Package.swift dependencies and identify clean build bottlenecks
- Run check_spm_pins.py on App.xcodeproj to inspect branch-tracked packages
- Check if Swift macros like TCA are causing full rebuild cascades

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: ac1b961ecd5cd491.

BEGIN THIRD-PARTY FILE ac1b961ecd5cd491
````text
---
name: spm-build-analysis
description: Analyze Swift Package Manager dependencies, package plugins, module variants, and CI-oriented build overhead that slow Xcode builds. Use when a developer suspects packages, plugins, or dependency graph shape are hurting clean or incremental build performance, mentions SPM slowness, package resolution time, build plugin overhead, duplicate module builds from configuration drift, circular dependencies between modules, oversized modules needing splitting, or modularization best practices.
---

# SPM Build Analysis

Use this skill when package structure, plugins, or dependency configuration are likely contributing to slow Xcode builds.

## Core Rules

- Treat package analysis as evidence gathering first, not a mandate to replace dependencies.
- Separate package-graph issues from project-setting issues.
- Do not rewrite package manifests or dependency sources without explicit approval.

## What To Inspect

- `Package.swift` and `Package.resolved`
- local packages vs remote packages
- package plugin and build-tool usage
- binary target footprint
- dependency layering, repeated imports, and potential cycles
- build logs or timing summaries that show package-related work

## Verification Before Recommending

Before including any local package in a recommendation, verify that it is actually part of the project's dependency graph. A `Vendor/` directory may contain packages that are not linked to any target.

- Check `project.pbxproj` for `XCLocalSwiftPackageReference` entries that reference the package path.
- Check `XCSwiftPackageProductDependency` entries to confirm the package's product is linked to at least one target.
- If a local package exists on disk but is not referenced in the project, do not include it in build-time recommendations.

When recommending version pins for branch-tracked dependencies:

- Use the helper script to scan all branch-pinned dependencies at once:
  ```bash
  python3 scripts/check_spm_pins.py --project App.xcodeproj
  ```
  This checks `git ls-remote --tags` for each branch-pinned package and reports which have tags available for pinning.
````
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