It describes a three-layered data architecture for a decentralized hiring/reputation protocol. Each layer has a clear purpose:

• The smart contract (on-chain) stores only the critical truth data that needs immutability (who is a reviewer, ratings, sponsorships, hiring outcomes).
• The Graph subgraph indexes those on-chain events, transforming them into structured entities for fast querying (users, ratings, sponsorships, balances, reputations).
• The off-chain database stores flexible, human-friendly data like profiles and job postings that don’t need to be on-chain.

1. Smart Contract Data (On-Chain)

• Holds state variables like admin, reviewer list, and reviewer mapping.
• Emits events for actions (approvals, ratings, credits spent, hiring decisions).
• Prioritizes immutability and gas efficiency over flexibility.

2. The Graph Subgraph (Indexed Queries)

• Creates entity models (User, Rating, Sponsorship) out of smart contract events.
• Enables querying and computation like reputation scores, ranking, filters, and relationships.
• For example, you can quickly ask: "What ratings did User X receive?" or "Which candidate got X sponsorships?"

3. Off-Chain Database (Profiles & Jobs)

• Stores user-friendly data (name, bio, job title, hiring manager identity).
• Linked to blockchain identity via wallet address.
• Flexible since it can be SQL or NoSQL, supporting frequent updates and richer profile content.

In short: on-chain = truth + security, subgraph = indexing + analytics, off-chain = profiles and jobs.