om-scogo Xcode Project Analyzer
Use this skill for project- and target-level build inefficiencies that are unlikely to be solved by source edits alone.
Core Rules
- Recommendation-first by default.
- Require explicit approval before changing project files, schemes, or build settings.
- Prefer measured findings tied to timing summaries, build logs, or project configuration evidence.
- Distinguish debug-only pain from release-only pain.
What To Review
- scheme build order and target dependencies
- debug vs release build settings against the build settings best practices
- run script phases and dependency-analysis settings
- derived-data churn or obviously invalidating custom steps
- opportunities for parallelization
- explicit module dependency settings and module-map readiness
- "Planning Swift module" time in the Build Timing Summary -- if it dominates incremental builds, suspect unexpected input modification or macro-related invalidation
- asset catalog compilation time, especially in targets with large or numerous catalogs
ExtractAppIntentsMetadatatime in the Build Timing Summary -- if this phase consumes significant time, record it asxcode-behavior(report the cost and impact, but do not suggest a repo-local optimization unless there is explicit Apple guidance)- zero-change build overhead -- if a no-op rebuild exceeds a few seconds, investigate fixed-cost phases (script execution, codesign, validation, CopySwiftLibs)
- CocoaPods usage -- if a
PodfileorPods.xcodeprojexists, CocoaPods is deprecated; recommend migrating to SPM and do not attempt CocoaPods-specific optimizations (see project-audit-checks.md) - Task Backtraces (Xcode 16.4+: Scheme Editor > Build > Build Debugging) to diagnose why tasks re-run unexpectedly in incremental builds
Build Settings Best Practices Audit
Every project audit should include a build settings checklist comparing the project's Debug and Release configurations against the recommended values in build-settings-best-practices.md. Present results using checkmark/cross indicators ([x]/[ ]). The scope is strictly build performance -- do not flag language-migration settings like SWIFT_STRICT_CONCURRENCY or SWIFT_UPCOMING_FEATURE_*.
Apple-Derived Checks
Review these items in every audit:
- target dependencies are accurate and not missing or inflated
- schemes build in
Dependency Order - run scripts declare inputs and outputs
.xcfilelistfiles are used when scripts have many inputs or outputsDEFINES_MODULEis enabled where custom frameworks or libraries should expose module maps- headers are self-contained enough for module-map use
- explicit module dependency settings are consistent for targets that should share modules
Typical Wins
- skip debug-time scripts that only matter in release
- add missing script guards or dependency-analysis metadata
- remove accidental serial bottlenecks in schemes
- align build settings that cause unnecessary module variants
- fix stale project structure that forces broader rebuilds than necessary
- identify linters or formatters that touch file timestamps without changing content, silently invalidating build inputs and forcing module replanning
- split large asset catalogs into separate resource bundles across targets to parallelize compilation
- use Task Backtraces to pinpoint the exact input change that triggers unnecessary incremental work
Reporting Format
For each issue, include:
- evidence
- likely scope
- why it affects clean builds, incremental builds, or both
- estimated impact
- approval requirement
If the evidence points to package graph or build plugins, hand off to spm-build-analysis by reading its SKILL.md and applying its workflow to the same project context.
Additional Resources
- For the detailed audit checklist, see references/project-audit-checks.md
- For build settings best practices, see references/build-settings-best-practices.md
- For the shared recommendation structure, see references/recommendation-format.md
- For Apple-aligned source summaries, see references/build-optimization-sources.md