Designing Chunk Metadata for a Multi-Tenant, Multi-Product Knowledge Base

You're chunking a knowledge base shared by a company with three products, each sold to hundreds of customer organizations (tenants), where some articles are public (visible to all tenants) and others are tenant-specific (custom integration docs written for one customer). Articles are also revised over time, and old revisions must remain queryable for support tickets referencing "what did the docs say when the customer signed up."

Design the metadata schema you'd attach to each chunk at ingestion time, and explain what retrieval-time problem each field solves.