---
name: platform-parity-review
description: Audit all documentation for platform-specific gaps across target platforms
summary: "Audits all documentation for platform-specific gaps — features missing on one platform, input pattern differences (touch vs. mouse), and platform-specific testing coverage."
phase: "parity"
order: 1010
dependencies: [review-architecture, review-database, review-api, review-ux]
outputs: [docs/reviews/platform-parity-review.md, docs/reviews/platform-parity/review-summary.md, docs/reviews/platform-parity/codex-review.json, docs/reviews/platform-parity/antigravity-review.json]
reads: [user-stories, coding-standards, tech-stack, project-structure, tdd, design-system]
conditional: "if-needed"
knowledge-base: [cross-phase-consistency, multi-model-review-dispatch, review-step-template, review-methodology]
---

## Purpose
When the project targets multiple platforms (web, iOS, Android, desktop), audit
all documentation to ensure every target platform is thoroughly addressed.
Identify gaps where one platform was assumed but another was not considered,
verify feature parity across targets, and ensure platform-specific testing,
input patterns, and UX considerations are documented.

At depth 4+, dispatches to external AI models (Codex, Antigravity) for
independent platform gap analysis.

## Conditional Evaluation
This step is conditional ("if-needed"). Enable when:
- The project targets 2+ platforms (e.g., web + mobile, iOS + Android)
- `docs/tech-stack.md` lists a cross-platform framework (React Native, Flutter, Expo)
- `docs/plan.md` mentions multiple deployment targets

Skip when the project targets a single platform only.

## Inputs
- docs/plan.md (required) — target platforms and version requirements
- docs/tech-stack.md (required) — cross-platform framework and build approach
- docs/user-stories.md (required) — stories to check for platform coverage
- docs/coding-standards.md (required) — platform-specific conventions
- docs/project-structure.md (optional) — platform-specific file organization
- docs/tdd-standards.md (optional) — platform-specific testing approach
- docs/design-system.md (optional) — responsive breakpoints and platform patterns
- docs/implementation-plan.md (optional — not available, runs before implementation-plan) — tasks covering each platform
- CLAUDE.md (required) — platform-specific workflow notes

## Expected Outputs
- docs/reviews/platform-parity-review.md — platform gap analysis report with
  findings per document, feature parity matrix, and recommended fixes
- docs/reviews/platform-parity/review-summary.md (depth 4+) — multi-model review synthesis
- docs/reviews/platform-parity/codex-review.json (depth 4+, if available) — raw Codex findings
- docs/reviews/platform-parity/antigravity-review.json (depth 4+, if available) — raw Antigravity findings

## Quality Criteria
- (mvp) All target platforms identified from PRD and tech-stack.md
- (mvp) Every user story checked for platform-specific acceptance criteria
- (deep) Feature parity matrix shows which features work on which platforms
- (deep) Input pattern differences documented (touch vs. mouse, keyboard shortcuts, gestures)
- (deep) Platform-specific testing documented (Playwright for web, Maestro for mobile)
- (deep) Navigation patterns appropriate per platform (sidebar vs. tab bar, etc.)
- (deep) Offline/connectivity handling addressed per platform (if applicable)
- (deep) Web version is treated as first-class (not afterthought) if PRD specifies it
- (mvp) Every finding categorized P0-P3 (P0 = Breaks downstream work. P1 = Prevents quality milestone. P2 = Known tech debt. P3 = Polish.)
- (mvp) Fix plan documented for all P0/P1 findings with specific document and section to update
- (depth 4+) Multi-model findings synthesized: Consensus (all models agree), Majority (2+ models agree), or Divergent (models disagree — present to user for decision)

## Methodology Scaling
- **deep**: Comprehensive platform audit across all documents, feature parity
  matrix, input pattern analysis, navigation pattern review, offline handling,
  accessibility per platform, and detailed fix recommendations. Multi-model
  review dispatched to Codex and Antigravity if available, with graceful fallback
  to Claude-only enhanced review.
- **mvp**: Quick check of user stories and tech-stack for platform coverage.
  Identify top 3 platform gaps. Skip detailed feature parity matrix.
- **custom:depth(1-5)**:
  - Depth 1: User stories platform check only (1 review pass)
  - Depth 2: Two-pass check — first pass validates user stories against platform constraints; second pass identifies implicit assumptions that could block native implementation (e.g., assumed web APIs not available on mobile).
  - Depth 3: Add tech-stack and coding-standards platform audit (3 review passes)
  - Depth 4: Add feature parity matrix + one external model if CLI available (3 review passes + external dispatch)
  - Depth 5: Full suite across all documents + multi-model with reconciliation (3 review passes + multi-model synthesis)

## Mode Detection
Update mode if docs/reviews/platform-parity-review.md exists. In update mode:
re-run audit against current documents, preserve prior findings still valid,
note which gaps have been addressed since last review. If multi-model review
artifacts exist under docs/reviews/platform-parity/, preserve prior findings
still valid.

## Update Mode Specifics
- **Detect prior artifact**: docs/reviews/platform-parity-review.md exists
- **Preserve**: existing parity findings still valid, platform-specific decisions,
  feature parity matrix entries for unchanged features
- **Triggers for update**: specification changes (tech-stack.md, user-stories.md,
  system-architecture.md updated), new target platform added to PRD, platform-specific
  coding standards changed
- **Conflict resolution**: preserve platform-specific decisions already made,
  merge new findings alongside existing ones rather than replacing