Use Case

As a... user of bson library
I want... calculateObjectSize() to return the exact byte count
So that... documents within the 16 MB limit are not incorrectly rejected client-side

User Experience

calculateObjectSize over-reports by 12 bytes per Int32 or BSONSymbol occurrence, causing valid documents to be rejected or buffers to be over-allocated

Dependencies

• None

Risks/Unknowns

• Low risk - no other types affected, no other branches (only size calculation)

Acceptance Criteria

Implementation Requirements

• Add an Int32 branch in calculateElementSize returning the correct 4-byte size.
• Fix the BSONSymbol type guard: 'Symbol' to 'BSONSymbol'.

Testing Requirements

• new unit tests

Documentation Requirements

• N/A

Follow Up Requirements

• N/A