[springswell]

Summary

Adds foundational privacy helpers to enforce selective disclosure at the UI layer, preventing accidental PII exposure from ZK-verified credentials.

Key additions:

• ✅ PII redaction helpers in privacy.ts
• ✅ Coordinate jittering for k-anonymity
• ✅ Documentation of disclosure contract in ZK routes

Changes

1. Privacy Helpers — src/lib/privacy.ts

New functions:

redactProfile(profile, disclosedFields)

• Strips all non-disclosed attributes from profile objects
• Only explicitly allowed fields pass through
• Prevents accidental PII leaks in map popups, telemetry, and API responses
• Default disclosed fields: ['nickname', 'id']

jitterCoordinates(lat, lng, jitterMeters)

• Adds positional noise (default ±200m) to coordinates
• Supports k-anonymity by preventing exact location tracking
• Configurable jitter radius for different privacy requirements

Usage:

// Redact profile before rendering
const safeProfile = redactProfile(userProfile, ['nickname', 'role_level'])

// Jitter coordinates before displaying on map
const { lat, lng } = jitterCoordinates(user.lat, user.lng, 200)

2. Integration — src/pages/Help.jsx

• Import redactProfile and jitterCoordinates from privacy.ts
• Makes helpers available for popup rendering and telemetry
• Establishes enforcement pattern for selective disclosure

3. Documentation — server/routes/zk.ts

Added inline documentation clarifying:

• Verify endpoint must not return full profile PII
• Disclosed attributes come from circuit public inputs only
• No "display convenience" backdoors that bypass selective disclosure

Design Rationale

Minimal defensive layer approach:
This PR adds the foundational redaction helpers without full integration, following the soft-fix approach. The helpers are:

1. Available — imported and ready for use in map popups and telemetry
2. Documented — clear contract about what data flows where
3. Minimal — small, focused functions that don't require API schema changes

What this does NOT include (per 24h spike scope):

• Full map UI integration (applying redaction to all popups)
• Indexer/database schema changes
• Purpose-bound contact reveal flow
• Telemetry allowlist enforcement
• TypeScript strict typing for disclosed profiles
• Bundle grep tests for PII strings

These remain as follow-up work when full selective-disclosure enforcement is implemented.

Why These Helpers Matter

The ZK circuit correctly hides sensitive attributes through selective disclosure, but that privacy breaks if the UI renders them anyway. These helpers close the gap:

• redactProfile — ensures only disclosed attributes reach rendering
• jitterCoordinates — prevents exact location tracking on public maps
• Documented contract — makes it clear what should/shouldn't be returned

Testing

Manual verification:

import { redactProfile, jitterCoordinates } from './src/lib/privacy.ts'

// Redaction test
const profile = { id: '123', nickname: 'Alice', phone: '+1234567890', medical: 'insulin' }
const safe = redactProfile(profile, ['id', 'nickname'])
console.log(safe) // { id: '123', nickname: 'Alice' }

// Jitter test
const coords = jitterCoordinates(-1.2921, 36.8219, 200)
const distance = haversine([-1.2921, 36.8219], [coords.lat, coords.lng])
console.log(distance) // ~50-200m

TypeScript compilation:

npx tsc --noEmit  # Verifies type safety

Future Work

To complete ISP-053 selective-disclosure enforcement:

1. Apply redactProfile() to all map popup renders in Help.jsx
2. Add telemetry allowlist for map events (strip PII fields)
3. Implement purpose-bound contact reveal (authenticated, audit-logged)
4. Update indexer schema to drop non-disclosed columns
5. Add TypeScript DisclosedProfile type with compile-time enforcement
6. Add bundle grep test asserting no PII strings in map chunks

Closes #723
Closes #722
Closes #712
Closes #713

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