Reduce duplication, improve developer experience, and increase long-term maintainability by consolidating and standardizing our TypeScript definitions.

Today, both projects independently define overlapping types for common MongoDB concepts such as ObjectId, Document, Projection, Query, and others. This leads to unnecessary divergence, inconsistent autocomplete and type inference, and added maintenance burden when upstream driver types change.

Proposed Benefits:

• Improved Developer Experience: Developers benefit from more consistent and accurate type definitions across both libraries, reducing friction when transitioning between the driver and Mongoose.
• Reduced Duplication: Shared types reduce redundant logic and boilerplate in Mongoose, allowing it to directly depend on or extend driver types where appropriate.
• Faster Iteration: Changes to shared types in the driver (e.g. new query operators, projection syntax) can automatically propagate to Mongoose with minimal effort.
• Greater Type Safety: Consistency between runtime behavior and static types improves correctness and confidence for TypeScript consumers.
• Long-Term Maintainability: A single source of truth for core MongoDB types simplifies future migrations and reduces divergence between ecosystem tools.

Scope of Consolidation (Initial Focus):

• ObjectId, Document, Projection, Filter, Sort, UpdateFilter, QueryOptions, and related generics
• Common utility types for Flatten, DeepPartial, etc.
• Query operator definitions ($eq, $in, $and, etc.)

Acceptance Criteria:

• An inventory is created comparing overlapping type definitions across mongodb and mongoose packages.
• A proposed shared type contract is documented and reviewed by maintainers of both projects.
• A shared internal package or type module is defined (if technically feasible), or a strategy for selective type re-exports is proposed.
• Mongoose types are refactored to use or extend from shared types where applicable, without regressing existing public type APIs.
• Automated tests are added to verify type compatibility and prevent future divergence.
• A changelog entry and migration notes are drafted for any breaking changes or improvements for downstream consumers.