Project stage?
├─ Greenfield (new project)
│  └─ Enable ALL gates from day 1
│     • SwiftLint (strict)
│     • SwiftFormat
│     • SWIFT_TREAT_WARNINGS_AS_ERRORS = YES
│     • Coverage > 80%
│
├─ Brownfield (legacy, no gates)
│  └─ Adopt incrementally:
│     1. SwiftLint with --baseline (ignore existing)
│     2. Format new files only
│     3. Gradually increase thresholds
│
└─ Existing project with some gates
   └─ Team size?
      ├─ Solo/Small (1-3) → Lint + Format sufficient
      └─ Medium+ (4+) → Full pipeline
         • Add coverage gates
         • Add static analysis
         • Add security scanning

What type of code?
├─ Domain/Business Logic
│  └─ 90%+ coverage required
│     • Business rules must be tested
│     • Silent bugs are expensive
│
├─ Data Layer (Repositories, Mappers)
│  └─ 85% coverage
│     • Test mapping edge cases
│     • Test error handling
│
├─ Presentation (ViewModels)
│  └─ 70-80% coverage
│     • Test state transitions
│     • Skip trivial bindings
│
└─ Views (SwiftUI)
   └─ Don't measure coverage
      • Snapshot tests or manual QA
      • Unit testing views has poor ROI

Starting fresh?
├─ YES → Enable opt_in_rules aggressively
│  └─ Easier to disable than enable later
│
└─ NO → Adopting on existing codebase
   └─ Use baseline approach:
      1. Run: swiftlint lint --reporter json > baseline.json
      2. Configure: baseline_path: baseline.json
      3. New violations fail, existing ignored
      4. Chip away at baseline over time

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**NEVER** use zero-tolerance for warnings initially on legacy code:
```bash

**NEVER** skip gates on "urgent" PRs:
```yaml

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**NEVER** use inline disables without explanation:
```swift
// ❌ No context
// swiftlint:disable force_unwrapping
let value = optionalValue!
// swiftlint:enable force_unwrapping

// ✅ Explain why exception is valid
// swiftlint:disable force_unwrapping
// Reason: fatalError path for corrupted bundle resources that should crash
let value = optionalValue!
// swiftlint:enable force_unwrapping

// ❌ Nuclear option hides real issues
// swiftlint:disable all

// ✅ Disable specific rules for specific lines
// swiftlint:disable:next identifier_name
let x = calculateX()  // Math convention

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**NEVER** run quality gates only on PR:
```yaml

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name: Quality Gates

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  # Fast gates first
  lint:
    runs-on: macos-14
    steps:
      - uses: actions/checkout@v4
      - run: brew install swiftlint swiftformat
      - run: swiftlint lint --strict --reporter github-actions-logging
      - run: swiftformat . --lint

  # Build only if lint passes
  build:
    needs: lint
    runs-on: macos-14
    steps:
      - uses: actions/checkout@v4
      - name: Build with strict warnings
        run: |
          xcodebuild build \
            -scheme App \
            -destination 'platform=iOS Simulator,name=iPhone 15' \
            SWIFT_TREAT_WARNINGS_AS_ERRORS=YES

  # Test only if build passes
  test:
    needs: build
    runs-on: macos-14
    steps:
      - uses: actions/checkout@v4
      - name: Test with coverage
        run: |
          xcodebuild test \
            -scheme App \
            -destination 'platform=iOS Simulator,name=iPhone 15' \
            -enableCodeCoverage YES \
            -resultBundlePath TestResults.xcresult

      - name: Check coverage threshold
        run: |
          COVERAGE=$(xcrun xccov view --report --json TestResults.xcresult | \
            jq '.targets[] | select(.name | contains("App")) | .lineCoverage * 100')
          echo "Coverage: ${COVERAGE}%"
          if (( $(echo "$COVERAGE < 80" | bc -l) )); then
            echo "❌ Coverage below 80%"
            exit 1
          fi

#!/bin/bash

---

Step 1: Measure current coverage
$ xcodebuild test -enableCodeCoverage YES ...
$ xcrun xccov view --report TestResults.xcresult

Step 2: Set threshold slightly below current
Current: 73% → Set threshold: 70%
Prevents regression without blocking

Step 3: Ratchet up over time
Week 1: 70%
Week 4: 75%
Week 8: 80%
Stop at: 80-85% (diminishing returns above)

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---