Flatten Nested JSON Config

MediumPython

Problem

Astra's IFS-supported systems store spacecraft configuration as nested JSON objects and arrays. Implement a function that flattens this structure into a dictionary whose keys represent each value's path.

Use dot notation for object keys and zero-based bracket notation for array indexes. For example, {"guidance": {"mode": "safe"}} becomes {"guidance.mode": "safe"}. Scalar values include strings, numbers, booleans, and null. Preserve empty nested objects and arrays as values at their paths. An empty root object or array produces {}.

Object keys are guaranteed not to contain . or bracket characters, so generated paths are unambiguous. The input root is always a JSON object or array. Because configurations may be deeply nested, the preferred solution should avoid Python's recursive call-depth limit.

Formal Specification

Input: config, a JSON-compatible Python dictionary or list.
Output: A dictionary mapping flattened string paths to scalar values or empty dictionaries/lists.
Path format: Object fields use ., and array elements use [index].

Constraints

1 <= total JSON nodes <= 200,000
Maximum nesting depth is 100,000
Object keys are non-empty strings without '.', '[' or ']'
Values are valid JSON types
The input root is a dictionary or list
The output contains one entry for every scalar or empty container

Function Signature

def flatten_config(config):

Formal Specification

Input: config, a JSON-compatible Python dictionary or list.
Output: A dictionary mapping flattened string paths to scalar values or empty dictionaries/lists.
Path format: Object fields use ., and array elements use [index].