Flatten / Map Nested JSON Between Modules

Problem
Map fields from one module's nested JSON output onto the next module's input shape, flattening or reshaping as needed. A mapping spec declares where each destination field pulls its value from in the source.

Input / Output

• Input: a source JSON object (arbitrarily nested) and a mapping spec of destination-path -> source-path.
• Output: a new object in the destination shape, values pulled from the source.

Constraints

• Arbitrary nesting depth.
• Source fields may be missing — must not throw; produce a sensible default or omit the key.

Example

• source {a:{b:1}}, spec {value: 'a.b'} -> {value: 1}
• missing path {value: 'a.x'} -> {value: undefined} (or key omitted).