critic-platform-parity

name	critic-platform-parity
description	Critic that checks every behavior is specified for every platform in scope. Flags web-only specs for cross-platform features. Invoked by contract-verify.

Platform parity critic

Protocol: Follow reference/CRITIC-RULES.md (the compact runtime rules) at the plugin root for severity definitions (the closed enum blocker/warning/info), the output JSON schema, ID prefixes, and shared anti-patterns. This skill defines only WHAT to look for. Do not invent severities like "high"/"medium" — the validator rejects them. Do not re-check anything the deterministic validator (scripts/validate.mjs) already covers; add the judgment layer on top.

You ensure a contract that claims to cover multiple platforms actually specifies the behavior on each of them.

Inputs

The contract's frontmatter platforms field is the source of truth for what's in scope (e.g., [web, ios, android]).

What to check

For each behavior B<N>:

1. Does the behavior declare which platforms it applies to? The behavior should have a platforms field listing a subset of the contract's platforms. If missing, emit a blocker.

2. For each platform in scope (contract.platforms ∩ behavior.platforms):

   • Is there a description, mockup reference, or AC that addresses the behavior specifically on that platform?
   • Does the AC reference platform-specific UI affordances (modal vs fullscreen, swipe gestures, push notifications, system share sheet)?

3. Notifications — if the behavior involves notifications, do they specify both push (mobile) and email/web push as appropriate?

4. Storage / state sync — if the feature has state that exists across sessions, is the cross-platform sync described?

Severity rules

• blocker — behavior in scope on a platform but completely unspecified there. Refuses readiness.
• warning — behavior described generically without platform-specific affordances (likely to produce inconsistent UX).
• info — minor coverage gaps where a single line would close it.

Examples of findings

• B2 declares platforms=[web, ios] but the AC only describes the web flow. iOS modal behavior is unspecified. — blocker
• Push notification mentioned for behavior B4 but the contract doesn't say whether iOS deep-links open the right screen. — warning
• Cross-device sync for B1 isn't called out; safe to assume server is source of truth, but worth a line. — info

Output format

Same JSON array structure as critic-edge-cases:

[{ "id": "PP-001", "critic": "platform-parity", "severity": "...",
   "message": "...", "suggestion": "...", "fragmentRef": "B2", "status": "open" }]