Minimal example of using Proof-Carrying Numbers (PCN) in a React app: a claims manager, provider, and ClaimMark components so numeric claims show ✓ (verified) or ⚠ (pending) against cached tool data.

1. ClaimsManager – Created once, with a createDataPointExtractor for a fake get_data tool that returns { data: [{ claim_id, OBS_VALUE, REF_AREA, TIME_PERIOD, ... }] }.
2. ClaimsProvider – Wraps the app so components can read claims and the manager.
3. Simulated tool result – On mount, the app calls manager.ingest("get_data", mockResult) with two data points (poverty rate 42%, GDP per capita 2.1k). Those claims are cached.
4. Message with claims – A simple message uses ClaimMark for:
   • 42% (policy percent) — cached as 0.42 → ✓ verified
   • 2.1k (policy abbr) — cached as 2100 → ✓ verified
   • about 5.2% (policy rounded, decimals 1) — no cached claim → ⚠ pending

From the repository root (so workspace deps resolve):

pnpm install
pnpm --filter pcn-example-chat-app dev

Then open http://localhost:5173.

Or from this directory after root install:

cd examples/chat-app
pnpm install
pnpm dev

pnpm --filter pcn-example-chat-app build
pnpm --filter pcn-example-chat-app preview

• @pcn/core – ClaimsManager, createDataPointExtractor, compareByPolicy
• @pcn/ui – ClaimsProvider, ClaimMark, useClaimsManager