Idea: Expose queryHash on QueryFunctionContext

[ElliotChong-MS]

Currently, query functions only receive queryKey, which forces consumers to either recompute the hash or perform an expensive find in the QueryCache to determine the canonical identifier for a query instance. This adds unnecessary complexity and overhead for libraries and applications that need a stable, unique identifier for queries.

The proposal is to expose queryHash directly on QueryFunctionContext. This value is already computed internally and used by the cache, so making it available is an additive, backward-compatible change. It provides a canonical identifier without requiring consumers to import internal utilities or replicate hashing logic.

This feature would simplify integrations, improve performance, and ensure correctness by giving developers a reliable, official identifier for queries. It’s a small change with significant ergonomic and efficiency benefits.

I'd be happy to create a PR to implement this change, please let me know if you'd be interested.

[ElliotChong-MS]

I created an associated PR for this proposal: #9812