axiom-build

name	axiom-build
description	Use when ANY iOS build fails, test crashes, Xcode misbehaves, or environment issue occurs before debugging code. Covers build failures, compilation errors, dependency conflicts, simulator problems, environment-first diagnostics.
license	MIT

Build & Environment

You MUST use this skill for ANY build, environment, or Xcode-related issue before debugging application code.

Auditors are skills here. Where this router says "Launch some-auditor agent", invoke the matching Codex skill instead — same procedure, no Claude Code agent required.

Available: axiom-modernize, axiom-scan-security-privacy.

The ones that shell out — builds, tests, simulators, crash symbolication — need shell access to run.

When to Use

Use this router when you encounter:

• Build failures (BUILD FAILED, compilation errors, linker errors)
• Test crashes or hangs
• Simulator issues (won't boot, device errors)
• Xcode misbehavior (stale builds, zombie processes)
• Dependency conflicts (CocoaPods, SPM)
• Build performance issues (slow compilation)
• Environment issues before debugging code

Routing Logic

This router invokes specialized skills based on the specific issue:

1. Environment-First Issues → xcode-debugging

Triggers:

• BUILD FAILED without obvious code cause
• Tests crash in clean project
• Simulator hangs or won't boot
• "No such module" after SPM changes
• Zombie xcodebuild processes
• Stale builds (old code still running)
• Clean build differs from incremental build
• Device Hub / predicted-vs-built issues in Xcode 27 (OS27)
• Reproducing a device-only bug on a simulator (Device Hub) (OS27)

Why xcode-debugging first: 90% of mysterious issues are environment, not code. Check this BEFORE debugging code.

Invoke: skills/xcode-debugging.md

---

2. Slow Builds → build-performance

Triggers:

• Compilation takes too long
• Type checking bottlenecks
• Want to optimize build time
• Build Timeline shows slow phases

Invoke: skills/build-performance.md

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3. SPM Dependency Conflicts → spm-conflict-resolver (Agent)

Triggers:

• SPM resolution failures
• "No such module" after adding package
• Duplicate symbol linker errors
• Version conflicts between packages
• Swift 6 package compatibility issues
• Package.swift / Package.resolved conflicts

Why spm-conflict-resolver: Specialized agent that analyzes Package.swift and Package.resolved to diagnose and resolve Swift Package Manager conflicts.

Invoke: axiom-resolve-spm

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4. Security & Privacy Audit → security-privacy-scanner (Agent)

Triggers:

• App Store submission prep
• Privacy Manifest requirements (iOS 17+)
• Hardcoded credentials in code
• Sensitive data storage concerns
• ATS violations
• Required Reason API declarations

Why security-privacy-scanner: Specialized agent that scans for security vulnerabilities and privacy compliance issues.

Invoke: axiom-scan-security-privacy

---

5. iOS 17→18 Modernization → modernization-helper (Agent)

Triggers:

• Migrate ObservableObject to @Observable
• Update @StateObject to @State
• Adopt modern SwiftUI patterns
• Deprecated API cleanup
• iOS 17+ migration

Why modernization-helper: Specialized agent that scans for legacy patterns and provides migration paths with code examples.

Invoke: axiom-modernize

---

6. Build Failure Auto-Fix → build-fixer (Agent)

Triggers:

• BUILD FAILED with no clear error details
• Build sometimes succeeds, sometimes fails
• App builds but runs old code
• "Unable to boot simulator" error
• Want automated environment-first diagnostics

Why build-fixer: Autonomous agent that checks zombie processes, Derived Data, SPM cache, and simulator state before investigating code. Saves 30+ minutes on environment issues.

Invoke: axiom-fix-build

---

7. Slow Build Optimization → build-optimizer (Agent)

Triggers:

• Builds take too long
• Want to identify slow type checking
• Expensive build phase scripts
• Suboptimal build settings
• Want parallelization opportunities

Why build-optimizer: Scans Xcode projects for build performance optimizations — slow type checking, expensive scripts, suboptimal settings — to reduce build times by 30-50%.

Invoke: axiom-optimize-build

---

8. General Dependency Issues → build-debugging

Triggers:

• CocoaPods resolution failures
• "Multiple commands produce" errors
• Framework version mismatches
• Non-SPM dependency graph conflicts

Invoke: skills/build-debugging.md

---

9. TestFlight Crash Triage → testflight-triage

Triggers:

• Beta tester reported a crash
• Crash reports in Xcode Organizer
• Crash logs aren't symbolicated
• TestFlight feedback with screenshots
• App was killed but no crash report

Why testflight-triage: Systematic workflow for investigating TestFlight crashes and reviewing beta feedback. Covers symbolication, crash interpretation, common patterns, and Claude-assisted analysis.

Invoke: See axiom-shipping (skills/testflight-triage.md)

---

10. App Store Connect Navigation → app-store-connect-ref

Triggers:

• How to find crashes in App Store Connect
• ASC metrics dashboard navigation
• Understanding crash-free users percentage
• Comparing crash rates between versions
• Exporting crash data from ASC
• App Store Connect API for crash data

Why app-store-connect-ref: Reference for navigating ASC crash analysis, metrics dashboards, and data export workflows.

Invoke: See axiom-shipping (skills/app-store-connect-ref.md)

---

11. Crash Log Analysis → crash-analyzer (Agent)

Triggers:

• User has .ips or .crash file to analyze
• User pasted crash report text
• Need to parse crash log programmatically
• Identify crash pattern from exception type
• Check symbolication status

Why crash-analyzer: Autonomous agent that parses crash reports, identifies patterns (null pointer, Swift runtime, watchdog, jetsam), and generates actionable analysis.

Invoke: axiom-analyze-crash

---

12. MetricKit API Reference → metrickit-ref

Triggers:

• MetricKit setup and subscription
• MXMetricPayload parsing (CPU, memory, launches, hitches)
• MXDiagnosticPayload parsing (crashes, hangs, disk writes)
• MXCallStackTree decoding and symbolication
• Field crash/hang collection
• Background exit metrics

Why metrickit-ref: Complete MetricKit API reference with setup patterns, payload parsing, and integration with crash reporting systems.

Invoke: See axiom-performance (skills/metrickit-ref.md)

---

13. Hang Diagnostics → hang-diagnostics

Triggers:

• App hangs or freezes
• Main thread blocked for >1 second
• UI unresponsive to touches
• Xcode Organizer shows hang diagnostics
• MXHangDiagnostic from MetricKit
• Watchdog terminations (app killed during launch/background transition)

Why hang-diagnostics: Systematic diagnosis of hangs with decision tree for busy vs blocked main thread, tool selection (Time Profiler, System Trace), and 8 common hang patterns with fixes.

Invoke: See axiom-performance (skills/hang-diagnostics.md)

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14. Live Debugging → lldb

Triggers:

• Need to reproduce a crash interactively
• Want to set breakpoints and inspect state
• Crash report analyzed, now need live investigation
• Need to attach debugger to running app

Why lldb: Crash reports tell you WHAT crashed. LLDB tells you WHY.

Invoke: skills/lldb.md

---

16. Runtime Console Capture → xclog-ref

Triggers:

• Need to see what the app is logging at runtime
• App crashes but no crash report (need console output)
• Silent failures (network, data, auth) with no UI feedback
• Want to capture print()/os_log() output from simulator
• Need structured log output for analysis
• "What is the app printing?"

Why xclog-ref: Xcode's debug console isn't accessible externally. xclog combines simctl stdout/stderr with log stream JSON to capture everything print(), NSLog(), os_log(), and Logger emit — with structured fields (level, subsystem, category) for automated analysis.

Invoke: /axiom:console (Claude Code only)

---

15. Code Signing Issues → code-signing

Triggers:

• "No signing certificate found"
• "Provisioning profile doesn't include signing certificate"
• errSecInternalComponent in CI
• ITMS-90035 Invalid Signature on upload
• Ambiguous identity / multiple certificates
• Entitlement mismatch or missing capability
• Setting up CI/CD code signing (GitHub Actions, fastlane match)
• Certificate expired or revoked

Why code-signing: Code signing errors are NEVER code bugs — they are 100% configuration (certificates, profiles, entitlements, keychains). Diagnosing with CLI tools takes 5 minutes vs hours of guessing.

Invoke: See axiom-security (skills/code-signing.md) (workflows) or See axiom-security (skills/code-signing-diag.md) (troubleshooting)

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Decision Tree

1. Mysterious/intermittent/clean build fails? → xcode-debugging (environment-first)
2. SPM dependency conflict? → spm-conflict-resolver (Agent)
3. CocoaPods/other dependency conflict? → build-debugging
4. Slow build time? → build-performance
5. Security/privacy/App Store prep? → security-privacy-scanner (Agent)
6. Want automated build fix (environment-first diagnostics)? → build-fixer (Agent)
7. Want build time optimization scan? → build-optimizer (Agent)
8. Modernization/deprecated APIs? → modernization-helper (Agent)
9. TestFlight crash/feedback? → testflight-triage
10. Navigating App Store Connect? → app-store-connect-ref
11. Have a crash log (.ips/.crash)? → crash-analyzer (Agent)
12. MetricKit setup/parsing? → metrickit-ref
13. App hang/freeze/watchdog? → hang-diagnostics
14. Need to reproduce crash interactively / inspect runtime state? → lldb
15. Code signing error (certificate, profile, entitlement, Keychain)? → code-signing / code-signing-diag
16. Need to see runtime console output (print/os_log)? → xclog-ref or /axiom:console (Claude Code only)

Anti-Rationalization

Thought	Reality
"I know how to fix this linker error"	Linker errors have 4+ root causes. xcode-debugging diagnoses all in 2 min.
"Let me just clean the build folder"	Clean builds mask the real issue. xcode-debugging finds the root cause.
"It's just an SPM issue, I'll fix Package.swift"	SPM conflicts cascade. spm-conflict-resolver analyzes the full dependency graph.
"The simulator is just slow today"	Simulator issues indicate environment corruption. xcode-debugging checks systematically.
"I'll skip environment checks, it compiles locally"	Environment-first saves 30+ min. Every time.
"I'll read the crash report more carefully instead of reproducing"	Crash reports show WHAT crashed, not WHY. Reproducing in LLDB with breakpoints reveals the actual state. skills/lldb.md has the workflow.
"I know my certificate is fine, let me check the code"	Code signing errors are NEVER code bugs. 100% configuration. code-signing diagnoses with CLI in 5 min.
"I can't see what the app is logging without Xcode"	xclog captures print() + os_log from the simulator. Structured JSON output with level, subsystem, category. /axiom:console (Claude Code only).

When NOT to Use (Conflict Resolution)

Do NOT use axiom-build for these — use the correct router instead:

Error Type	Correct Router	Why NOT axiom-build
Swift 6 concurrency errors	/skill axiom-concurrency	Code error, not environment
SwiftData migration errors	/skill axiom-data	Schema issue, not build environment
"Sending 'self' risks data race"	/skill axiom-concurrency	Language error, not Xcode issue
Type mismatch / compilation errors	Fix the code	These are code bugs

axiom-build is for environment mysteries, not code errors:

• ✅ "No such module" when code is correct
• ✅ Simulator won't boot
• ✅ Clean build fails, incremental works
• ✅ Zombie xcodebuild processes
• ❌ Swift concurrency warnings/errors
• ❌ Database migration failures
• ❌ Type checking errors in valid code

Example Invocations

User: "My build failed with a linker error" → Invoke: skills/xcode-debugging.md (environment-first diagnostic)

User: "Builds are taking 10 minutes" → Invoke: skills/build-performance.md

User: "SPM won't resolve dependencies" → Invoke: spm-conflict-resolver agent

User: "Two packages require different versions of the same dependency" → Invoke: spm-conflict-resolver agent

User: "Duplicate symbol linker error" → Invoke: spm-conflict-resolver agent

User: "I need to prepare for App Store security review" → Invoke: security-privacy-scanner agent

User: "Do I need a Privacy Manifest?" → Invoke: security-privacy-scanner agent

User: "Are there hardcoded credentials in my code?" → Invoke: security-privacy-scanner agent

User: "How do I migrate from ObservableObject to @Observable?" → Invoke: modernization-helper agent

User: "Update my code to use modern SwiftUI patterns" → Invoke: modernization-helper agent

User: "Should I still use @StateObject?" → Invoke: modernization-helper agent

User: "A beta tester said my app crashed" → Invoke: See axiom-shipping (skills/testflight-triage.md)

User: "I see crashes in App Store Connect but don't know how to investigate" → Invoke: See axiom-shipping (skills/testflight-triage.md)

User: "My crash logs aren't symbolicated" → Invoke: See axiom-shipping (skills/testflight-triage.md)

User: "I need to review TestFlight feedback" → Invoke: See axiom-shipping (skills/testflight-triage.md)

User: "How do I find crashes in App Store Connect?" → Invoke: See axiom-shipping (skills/app-store-connect-ref.md)

User: "Where's the crash-free users metric in ASC?" → Invoke: See axiom-shipping (skills/app-store-connect-ref.md)

User: "How do I export crash data from App Store Connect?" → Invoke: See axiom-shipping (skills/app-store-connect-ref.md)

User: "Analyze this crash log" [pastes .ips content] → Invoke: crash-analyzer agent or axiom-analyze-crash

User: "Parse this .ips file: ~/Library/Logs/DiagnosticReports/MyApp.ips" → Invoke: crash-analyzer agent or axiom-analyze-crash

User: "Why did my app crash? Here's the report..." → Invoke: crash-analyzer agent or axiom-analyze-crash

User: "How do I set up MetricKit to collect crash data?" → Invoke: See axiom-performance (skills/metrickit-ref.md)

User: "How do I parse MXDiagnosticPayload?" → Invoke: See axiom-performance (skills/metrickit-ref.md)

User: "What's in MXCallStackTree and how do I decode it?" → Invoke: See axiom-performance (skills/metrickit-ref.md)

User: "My app hangs sometimes" → Invoke: See axiom-performance (skills/hang-diagnostics.md)

User: "The main thread is blocked and UI is unresponsive" → Invoke: See axiom-performance (skills/hang-diagnostics.md)

User: "Xcode Organizer shows hang diagnostics for my app" → Invoke: See axiom-performance (skills/hang-diagnostics.md)

User: "My app was killed by watchdog during launch" → Invoke: See axiom-performance (skills/hang-diagnostics.md)

User: "I have a crash report and need to reproduce it in the debugger" → Invoke: skills/lldb.md

User: "How do I set breakpoints to catch this crash?" → Invoke: skills/lldb.md

User: "My build is failing with BUILD FAILED but no error details" → Invoke: build-fixer agent or axiom-fix-build

User: "Build sometimes succeeds, sometimes fails" → Invoke: build-fixer agent or axiom-fix-build

User: "How can I speed up my Xcode build times?" → Invoke: build-optimizer agent or axiom-optimize-build

User: "No signing certificate found when I try to build" → Invoke: See axiom-security (skills/code-signing-diag.md)

User: "errSecInternalComponent in my GitHub Actions CI" → Invoke: See axiom-security (skills/code-signing-diag.md)

User: "How do I set up code signing for GitHub Actions?" → Invoke: See axiom-security (skills/code-signing.md)

User: "What is my app printing to the console?" → Invoke: /axiom:console (Claude Code only)

User: "I need to see the simulator console output" → Invoke: /axiom:console (Claude Code only)

User: "The app fails silently, no error in the UI" → Invoke: /axiom:console (Claude Code only)