Archery Apprentice Documentation

Week 17: iOS Investigation & ViewModel Pattern (Parallel Execution)

10 min read

Week 17: iOS Investigation & ViewModel Pattern (Parallel Execution)

Overview

Strategy: Parallel Execution (Option C) Duration: 5 days (November 2025) Status: Partial (iOS 60% complete, ViewModels 100% complete) Agents: Agent 1 (AAP - iOS), Agent 2 (AAM - ViewModels), Agent 3 (AAA - Validation)

Two Parallel Tracks:

  1. Track 1 (Agent 1): iOS Firebase SDK investigation and PoC implementation
  2. Track 2 (Agent 2): Simple ViewModel → Presenter pattern establishment

Executive Summary

Week 17 executed a parallel development strategy to maximize velocity while Firebase abstraction unblocked iOS work. Agent 1 investigated iOS Firebase SDK options and delivered a validated PoC with GitLive Firebase KMP SDK, achieving 52% code reduction versus native implementations. Agent 2 established the ViewModel → Presenter pattern by migrating 6 simple equipment ViewModels, achieving 68% average code reduction and proving iOS-compatible architecture.

Key Achievement: Validated iOS technical path forward (GitLive SDK, 80% confidence) while simultaneously establishing presentation layer migration pattern for iOS code sharing.

Deferred: iOS runtime validation awaits macOS availability (environmental constraint, not technical blocker).

Track 1: iOS Firebase Investigation (Agent 1)

Status: 60% Complete (static validation done, runtime deferred) Deliverables: 3,428 lines (spike reports + PoC + documentation) Quality: 4.75/5 average (5/5 spike, 4.5/5 PoC static)

Phase 1: iOS Firebase SDK Spike (Days 1-2)

Objective: Evaluate GitLive KMP SDK vs Native iOS SDK for RemoteTournamentDataSource implementation.

Documentation Delivered:

  • IOS_FIREBASE_SPIKE_REPORT.md (841 lines) - Comprehensive comparison
  • IOS_POC_DESIGN.md (545 lines) - Implementation design

Comparison Results:

CriterionGitLive KMP SDKNative iOS SDKWinner
Code Sharing80-90% shared0% (duplicate Swift)GitLive
MaintenanceSingle codebaseDual maintenanceGitLive
Feature Parity95% (27/27 methods)100%Native (slight edge)
CommunityMedium (KMP ecosystem)Large (official support)Native
RiskMedium (community-maintained)Low (Google-backed)Native

Recommendation: GitLive Firebase KMP SDK (80% confidence)

Rationale:

  • 52% code reduction: 136 shared lines (KMP) vs 286+ duplicated lines (Android + iOS native)
  • 27/27 methods supported: Full RemoteTournamentDataSource interface coverage
  • Real-time listeners: Properly abstracts callbackFlow pattern for iOS
  • Trade-offs accepted: Manual CocoaPods setup, community support vs code duplication

User Decision: APPROVED - Proceed to PoC validation

Agent 3 Validation: ⭐⭐⭐⭐⭐ (5/5 - EXCELLENT)

Phase 2: GitLive PoC Implementation (Days 3-5)

Objective: Validate GitLive SDK with static implementation and iOS target compilation.

Implementation:

  • RemoteTournamentDataSource.kt (85 lines, commonMain) - Platform-agnostic interface
  • GitLiveFirebaseDataSource.kt (117 lines, commonMain) - Shared implementation for Android + iOS

Documentation Delivered:

  • GITLIVE_POC_REPORT.md (676 lines) - PoC findings and trade-offs
  • IOS_COCOAPODS_SETUP.md (278 lines) - iOS integration guide
  • IOS_SWIFT_USAGE_GUIDE.md (479 lines) - Swift consumption patterns

Static Validation Results:

  • ✅ iOS targets compile successfully
  • ✅ Interface accessible from Swift (Objective-C header generation verified)
  • ✅ Flow types properly bridged to Swift
  • ✅ Result types correctly exposed

Deferred (Environmental Constraint):

  • ❌ Runtime validation requires macOS (unavailable for few weeks)
  • 5 critical tests deferred:
    1. Authentication flow (Firebase Auth integration)
    2. Flow observation in Swift (real-time listener behavior)
    3. Performance benchmarks (iOS device testing)
    4. Edge case handling (error propagation, network failures)
    5. Build integration (CocoaPods + Xcode build)

Resume Plan (When macOS Available):

  1. Create minimal iOS app (1 day)
  2. Run 5 critical runtime tests
  3. Final GO/NO-GO decision
  4. If GO → Full implementation (27 methods)
  5. If NO-GO → Pivot to Native Swift SDK

Agent 3 Validation: ⭐⭐⭐⭐½ (4.5/5 - CONDITIONAL GO)

  • Rating: EXCELLENT with runtime caveat
  • Recommendation: Static validation successful, proceed with runtime deferred

Track 2: ViewModel → Presenter Migrations (Agent 2)

Status: 100% Complete (6/6 ViewModels migrated) Deliverables: 1,091 lines (presenters + repository interfaces + implementations) Quality: ⭐⭐⭐⭐⭐ (5/5 - EXCELLENT)

Pattern Establishment

Goal: Migrate simple equipment ViewModels to establish iOS-compatible Presenter pattern.

Architecture Pattern:

Before (Android-only):

┌──────────────┐
│  ViewModel   │  ← Android-only (ViewModel base class)
│  (Android)   │     Business logic in platform code
└──────┬───────┘
       │
   ┌───▼────────┐
   │ Repository │
   │ (Android)  │
   └────────────┘

❌ Cannot share with iOS
❌ Business logic duplicated
❌ Platform-specific base class

After (KMP-compatible):

┌─────────────────────┐
│  shared:presentation │  ← Presenter (KMP)
│   Presenter.kt       │     All business logic
│   (commonMain)       │     80-90% code reuse
└─────────┬────────────┘
          │
     ┌────▼─────────────┐
     │  shared:data     │  ← Repository Interface
     │  Repository.kt   │     (KMP-compatible)
     │  (commonMain)    │
     └────┬─────────────┘
          │
   ┌──────▼───────┬──────────┐
   │   Android    │   iOS    │  ← Platform implementations
   │ RepositoryImpl│ (Future) │
   └──────────────┴──────────┘

✅ Business logic shared (KMP)
✅ iOS can implement Repository
✅ ViewModels become thin wrappers

ViewModels Migrated (6 Total)

Batch 1: Simple Equipment ViewModels

ViewModelBeforeAfterReductionStatus
LimbsViewModel150 lines48 lines68%✅
RiserViewModel153 lines49 lines68%✅
WeightViewModel160 lines55 lines66%✅
RestViewModel167 lines50 lines70%✅
StabilizerViewModel168 lines54 lines68%✅
AccessoryViewModel178 lines54 lines70%✅

Total Code Reduction: 976 → 310 lines (68% average)

Why This Matters:

  • Business logic now in shared:presentation (KMP-compatible)
  • ViewModels reduced to thin wrappers (SavedStateHandle, lifecycle management)
  • iOS can reuse Presenters directly from Swift (80-90% code sharing)

Infrastructure Created

1. SaveResult Sealed Class (shared:domain):

sealed class SaveResult {
    data object Success : SaveResult()
    data class Error(val message: String) : SaveResult()
    data object ValidationError : SaveResult()
}

Why: Platform-agnostic success/error handling (no Android-specific types)

2. Repository Interfaces (shared:data, 6 total):

  • LimbsRepository.kt
  • RiserRepository.kt
  • WeightRepository.kt
  • RestRepository.kt
  • StabilizerRepository.kt
  • AccessoryRepository.kt

Why: iOS can implement interfaces with iOS-specific Firebase SDK

3. Presenters (shared:presentation, 973 lines total):

  • All business logic migrated from ViewModels
  • Full CRUD operations
  • State management (StateFlow patterns)
  • Validation logic

4. RepositoryImpl Classes (app module):

  • Android-specific implementations
  • Firebase SDK integration
  • Preserves existing behavior

Quality Metrics

Test Coverage:

  • ✅ 100% maintained (zero regressions)
  • ✅ All 4,090 tests passing
  • ✅ No behavioral changes (validation confirmed)

Code Quality:

  • ✅ Pattern consistency (6/6 ViewModels follow same structure)
  • ✅ KMP compatibility verified
  • ✅ iOS-ready architecture

Documentation:

  • ✅ Pattern guide created
  • ✅ Migration checklist documented
  • ✅ Ready to scale to medium-complexity ViewModels

Parallel Execution Strategy

Decision: Option C (Parallel Tracks)

Rationale:

  • iOS work independent of ViewModel work
  • No blocking dependencies between tracks
  • Maximize velocity (both tracks progress simultaneously)
  • Multiple validation checkpoints (quality maintained)

Benefits Realized:

  • ✅ No time wasted waiting (5 days vs 7-8 days sequential)
  • ✅ iOS data informs long-term planning
  • ✅ ViewModel work progressed immediately after Firebase abstraction
  • ✅ Multiple validation cycles (Agent 3 delivered 4 reports)

Challenges:

  • Workflow gap: Agents didn’t auto-push branches (required orchestrator reminders)
  • Environmental constraint: iOS requires macOS (identified early, deferred safely)
  • Validation dependencies: Small delays waiting for branch pushes

Recommendation: Continue parallel execution for Week 18+ (proven effective)

Key Decisions

Decision 1: GitLive Firebase KMP SDK (HIGH Confidence)

Recommendation: GitLive Firebase KMP SDK Confidence: 80% (APPROVED) User Decision: Proceed to PoC validation

Why GitLive:

  • 52% code reduction (136 shared vs 286+ duplicated)
  • 27/27 methods supported (full RemoteTournamentDataSource coverage)
  • Proven KMP ecosystem integration (callbackFlow, coroutines)

Trade-offs Accepted:

  • Manual CocoaPods setup (vs SPM auto-config)
  • Community support (vs official Google SDK)
  • Medium-sized community (vs large iOS ecosystem)

Validation Path:

  • ✅ Static validation (4.5/5) - PoC compiles, types exposed correctly
  • ⏳ Runtime validation deferred (macOS unavailable)

Decision 2: Defer iOS Runtime Validation (Option C)

Blocker: macOS unavailable for few weeks Decision: Defer iOS runtime, continue ViewModel work Rationale: iOS work preserved at 60%, ViewModel track unblocked

iOS Work Preserved:

  • ✅ Spike report (841 lines)
  • ✅ PoC design (545 lines)
  • ✅ GitLive implementation (117 lines)
  • ✅ Documentation (1,433 lines)
  • ✅ Static validation (4.5/5)

Resume Plan: 1-2 days runtime validation when macOS available

Decision 3: Continue ViewModel Migrations

Day 2 Checkpoint: Agent 3 validation ⭐⭐⭐⭐⭐ (5/5) User Decision: Continue Days 3-5 Result: 6/6 ViewModels complete (pattern proven)

Why Continue:

  • Pattern validated (68% average code reduction)
  • Zero regressions (test coverage maintained)
  • iOS path clear (business logic now shareable)

Metrics

Combined Week 17 Output

Total Deliverables: ~5,000 lines

  • iOS work: 3,428 lines (spike + PoC + docs)
  • ViewModel work: 1,091 lines (presenters + repositories + implementations)
  • Validation reports: 4 comprehensive reports

Code Reduction:

  • iOS: 52% (136 shared vs 286+ duplicated)
  • ViewModels: 68% average (976 → 310 lines)

Quality:

  • Test pass rate: 100% (4,090/4,090 tests)
  • Zero regressions maintained
  • Agent 3 validations: 4.88/5 average (EXCELLENT)

Agent Contributions

Agent 1 (Architecture & Patterns):

  • iOS Spike Report (841 lines, 5/5 validation)
  • PoC Design (545 lines)
  • GitLive PoC implementation (117 lines, 4.5/5 validation)
  • Documentation: CocoaPods setup, Swift usage guide

Agent 2 (Modules & Data Layer):

  • 6 Presenters migrated (973 lines)
  • 6 Repository interfaces (shared:data)
  • 6 RepositoryImpl classes (app)
  • SaveResult sealed class infrastructure

Agent 3 (Analysis & Assurance):

  • 4 validation reports delivered:
    1. iOS Spike: ⭐⭐⭐⭐⭐ (5/5)
    2. Day 2 Checkpoint: ⭐⭐⭐⭐⭐ (5/5)
    3. GitLive PoC Static: ⭐⭐⭐⭐½ (4.5/5)
    4. Final Week 17: ⭐⭐⭐⭐⭐ (5/5)

Lessons Learned

What Worked Well

  1. Parallel Execution Maximized Velocity:

    • 5 days vs 7-8 days sequential (30% time savings)
    • No blocking dependencies between tracks
    • Both tracks delivered high-quality output

  2. Evidence-Based Decisions:

    • iOS spike data (841 lines) informed GitLive SDK choice
    • 52% code reduction quantified vs native approach
    • Static validation de-risked runtime deferral

  3. Environmental Constraint Handling:

    • Identified early (Day 2)
    • Deferred safely (iOS work preserved at 60%)
    • Alternative track unblocked (ViewModel migrations)

  4. Pattern Establishment:

    • 6/6 ViewModels migrated (consistent 68% reduction)
    • Pattern documented and ready to scale
    • iOS code sharing path proven

Challenges & Improvements

  1. Workflow Gaps:

    • Issue: Agents didn’t auto-push branches
    • Impact: Orchestrator reminders needed for validation handoffs
    • Fix: Add automated push step to agent workflows (Week 18+)

  2. Environmental Constraints:

    • Issue: iOS requires macOS (unavailable for few weeks)
    • Impact: Runtime validation deferred (60% complete)
    • Mitigation: Static validation excellent (4.5/5), resume plan clear

  3. Validation Dependencies:

    • Issue: Small delays waiting for branch pushes
    • Impact: 1-2 hour delays between milestones
    • Fix: Parallel validation prep (Agent 3 can start while Agent 1/2 push)

What This Unblocks

Immediate (Week 18)

If macOS Available Early:

  • ✅ iOS runtime validation (1-2 days)
  • ✅ Final GO/NO-GO decision on GitLive SDK
  • ✅ Full RemoteTournamentDataSource implementation (27 methods)

If macOS Still Unavailable:

  • ✅ Continue ViewModel migrations (medium complexity)
  • ✅ Scale pattern to 9 ViewModels total
  • ✅ Target: EquipmentListViewModel, RoundScoringViewModel, TournamentDetailsViewModel

Long-term (Week 19+)

iOS Implementation:

  • ✅ iOS app can consume Presenters from Swift (80-90% code reuse)
  • ✅ iOS can implement Repository interfaces
  • ✅ Business logic shared (no duplication)

Presentation Layer Migration:

  • ✅ Pattern proven (6/6 ViewModels, 68% reduction)
  • ✅ Ready to scale to 30+ ViewModels
  • ✅ iOS-compatible architecture established

Week 17 Primary Documentation

iOS Track (Agent 1):

ViewModel Track (Agent 2):

  • Session Wrap-Up: docs/AGENT_MESSAGES/WEEK_17/WEEK_17_SESSION_WRAP_UP.md

Validation Reports (Agent 3):

  • docs/AGENT_MESSAGES/WEEK_17/AGENT_3_IOS_SPIKE_VALIDATION_REPORT.md (5/5)
  • docs/AGENT_MESSAGES/WEEK_17/AGENT_3_DAY_2_CHECKPOINT_VALIDATION_REPORT.md (5/5)
  • docs/AGENT_MESSAGES/WEEK_17/AGENT_3_GITLIVE_POC_VALIDATION_REPORT.md (4.5/5)
  • docs/AGENT_MESSAGES/WEEK_17/AGENT_3_FINAL_WEEK_17_VALIDATION_REPORT.md (5/5)

Previous:

Next:

Cross-References

Quality Assurance

Agent 3 (Validation) Summary

Overall Rating: 4.88/5 (EXCELLENT)

iOS Spike Validation:

  • Rating: ⭐⭐⭐⭐⭐ (5/5 - EXCELLENT)
  • Recommendation: GitLive SDK (HIGH confidence)
  • Evidence-based approach validated

Day 2 Checkpoint (ViewModel):

  • Rating: ⭐⭐⭐⭐⭐ (5/5 - EXCELLENT)
  • Pattern established (68% code reduction)
  • Zero regressions confirmed

GitLive PoC Static Validation:

  • Rating: ⭐⭐⭐⭐½ (4.5/5 - CONDITIONAL GO)
  • Static validation successful
  • Runtime deferred (macOS constraint)
  • Recommendation: Proceed with runtime when available

Final Week 17 Validation:

  • Rating: ⭐⭐⭐⭐⭐ (5/5 - EXCELLENT)
  • All P0 criteria met
  • Quality maintained across both tracks
  • Parallel execution validated as effective strategy

Pull Requests

Week 17 PRs:

  • PR #206: Week 17 Documentation (Agent 3)
  • PR #207: iOS GitLive PoC (Agent 1)
  • PR #208: ViewModel Migrations (Agent 2)

Tags: architecture kmp ios firebase viewmodel presenter parallel-execution week-17 gitlive pattern-establishment

Graph View

Backlinks