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README.md
<a href="https://www.rocketsim.app"><img src="assets/xcode-build-optimization-banner.jpg" alt="Xcode Build Optimization Agent Skills - Monitor your build performance with RocketSim" /></a>
Xcode Build Optimization Agent Skills
Open-source Agent Skills for benchmarking and optimizing Xcode build performance across clean builds, incremental builds, compile hotspots, project settings, and Swift Package Manager overhead.
Quick Start
Install all six skills (the orchestrator needs the specialist skills to work):
Then open your Xcode project in your AI coding tool and say:
Use the /xcode-build-orchestrator skill to analyze build performance and come up with a plan for improvements.
The agent will benchmark your clean and incremental builds, audit build settings, find compile hotspots, and produce an optimization plan at .build-benchmark/optimization-plan.md. No project files are modified until you explicitly approve changes.
A 1-second improvement on a 30-second incremental build sounds small. At 50 builds a day, that adds up to 3.5 hours per developer per year -- or 35 hours across a team of ten.
Most projects have several seconds of easy wins hiding in build settings, script phases, and compiler flags. This skill finds them.
How It Works
The orchestrator coordinates five specialist skills in a recommend-first workflow. Nothing is modified until you approve.
flowchart LR
Orchestrator --> Benchmark["Benchmark\n(clean + incremental)"]
Benchmark --> Compilation["Compilation\nAnalyzer"]
Benchmark --> Project["Project\nAnalyzer"]
Benchmark --> SPM["SPM\nAnalyzer"]
Compilation --> Plan["Optimization\nPlan"]
Project --> Plan
SPM --> Plan
Plan --> You{{"You review\n& approve"}}
You --> Fixer["Build\nFixer"]
Fixer --> ReBenchmark["Re-benchmark\n& verify"]
<!-- BEGIN SKILL STRUCTURE -->
<!-- END SKILL STRUCTURE -->
Phase 1 -- Analyze. The orchestrator benchmarks your project, runs the three specialist analyzers, and produces a prioritized optimization plan at .build-benchmark/optimization-plan.md. No project files are modified.
Use the Xcode build orchestrator to analyze build performance and come up with a plan for improvements.
Phase 2 -- Fix. Review the plan, check the approval boxes for the items you want, and ask the agent to apply them. The fixer implements only approved changes and re-benchmarks to verify.
Implement the approved items from the optimization plan at .build-benchmark/optimization-plan.md, then re-benchmark to verify the improvements.
The plan file is your evidence trail -- shareable with teammates, reviewable in PRs, and diffable over time.
What It Checks
The agent runs over 40 individual checks across build settings, project configuration, source code, and package dependencies.
Real-world improvements reported by developers who used these skills. Add your own by opening a pull request.
The xcode-build-orchestrator generates your table row at the end of every optimization run, so contributing is a single copy-paste.
[!NOTE]
A small clean-build increase is normal when enabling compilation caching -- the first cold build populates the cache. Cached clean builds (branch switching, pulling changes) and incremental builds are where the real gains show up.
developers investigating a recent build-time regression
teams that want evidence-backed Xcode build optimization instead of guesswork
developers who want a reusable Agent Skills package, not a one-off script
Included Skills
| Skill | Purpose |
|-------|---------|
| xcode-build-orchestrator | End-to-end workflow: benchmark, analyze, prioritize, approve, fix, re-benchmark |
| xcode-build-benchmark | Repeatable clean and incremental build benchmarks with timestamped artifacts |
| xcode-compilation-analyzer | Swift compile hotspot analysis and source-level recommendations |
| xcode-project-analyzer | Build settings, scheme, script phase, and target dependency auditing |
| spm-build-analysis | Package graph, plugin overhead, and module variant review |
| xcode-build-fixer | Apply approved optimization changes and verify with benchmarks |
The orchestrator is the recommended starting point -- it coordinates the other five skills automatically. Install all six skills so the orchestrator can access each specialist.
Installation Options
Option A: Using skills.sh
Install all six skills (required -- the orchestrator depends on the specialist skills):
Available individual skills: xcode-build-benchmark, xcode-compilation-analyzer, xcode-project-analyzer, spm-build-analysis, xcode-build-orchestrator, xcode-build-fixer. Note that the orchestrator requires all other skills to be installed.
Each skill bundles its own copies of the scripts, references, and schemas it needs so it works after standalone installation. The canonical copies live at the repo root:
scripts/ -- helper scripts for benchmarking, timing-summary parsing, compilation diagnostics, report generation, and recommendation rendering
references/ -- build settings best practices, artifact format, recommendation format, and source citations
schemas/ -- JSON schema for benchmark output
When a root-level file changes, the corresponding copies inside each skill that uses it must be updated (see CONTRIBUTING.md).
All checks are grounded in Apple documentation, WWDC sessions, and proven community practices. See OPTIMIZATION-CHECKS.md for the full list of checks with references to each source.
The stored reference summaries live in references/build-optimization-sources.md.
RocketSim Positioning
This repo helps you optimize point-in-time build performance with an agent-guided workflow.
RocketSim complements it by monitoring build performance over time:
automatic clean vs incremental build tracking
duration trends and percentile metrics
machine, Xcode, and macOS comparisons
team-wide visibility without custom build scripts
If you want to catch regressions earlier and see whether your build times are improving over weeks or months, use RocketSim Build Insights after you apply the improvements from this repo.
Contributing
Contributions are welcome when they keep the repo focused on Xcode build optimization and Agent Skills format quality.