Add recursive nested filter support to MongoDB driver

[Copilot]

The MongoDB driver failed on nested filter expressions like [['a','=',1], 'or', [['b','=',2], 'and', ['c','=',3]]] while the SQL driver handled them correctly.

Changes

• Refactored mapFilters into recursive helpers:

  • buildFilterConditions() - processes filter arrays recursively with AND/OR logic
  • buildSingleCondition() - builds individual MongoDB conditions

• Added heuristic detection - distinguishes criterion [field, op, value] from nested groups by checking if first two elements are strings

• Proper operator nesting - tracks join state to correctly generate $and/$or at each nesting level

Example

Input filter:

[
  [['status', '=', 'completed'], 'and', ['amount', '>', 100]],
  'or',
  [['customer', '=', 'Alice'], 'and', ['status', '=', 'pending']]
]

Generates:

{
  $or: [
    { $and: [{ status: { $eq: 'completed' } }, { amount: { $gt: 100 } }] },
    { $and: [{ customer: { $eq: 'Alice' } }, { status: { $eq: 'pending' } }] }
  ]
}

Backward compatible with flat filter arrays. Achieves parity with SQL driver using identical recursive approach.

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Enhancement: Support nested filters in Mongo Driver</issue_title>
<issue_description>## Problem
The current packages/drivers/mongo implementation matches flat arrays but fails on recursive/nested logic (e.g. [['a','=',1], 'or', [['b','=',2], 'and', ['c','=',3]]]), which the SQL driver supports.

Goal

• Refactor mapFilters in Mongo driver to recursively parse nested arrays.
• Ensure parity with SQL driver query capabilities.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Enhancement: Support nested filters in Mongo Driver #23

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[Copilot]

Pull request overview

This pull request adds recursive nested filter support to the MongoDB driver, achieving parity with the SQL driver for complex nested filter expressions.

Changes:

• Refactored filter handling into recursive helpers (buildFilterConditions and buildSingleCondition)
• Added heuristic detection to distinguish between single criterion [field, op, value] and nested filter groups
• Implemented proper operator nesting with $and/$or at each recursion level

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
packages/drivers/mongo/src/index.ts	Refactored mapFilters into recursive buildFilterConditions and buildSingleCondition methods with support for nested filter groups and AND/OR operators
packages/drivers/mongo/test/index.test.ts	Added unit tests for nested filter groups, deeply nested filters, and implicit AND handling with expected MongoDB query structures
packages/drivers/mongo/test/integration.test.ts	Added integration tests for nested and deeply nested filters with real data validation