Sample
Build dynamic proto3 message classes without protoc while preserving field presence and 64-bit values through binary and JSON round trips
sha256:db90b829f35bd858faf7529ca149fcf58bfe9c65c18c586e7237ddb5084c0b1a
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Case
- Goal
- Build dynamic proto3 message classes without protoc while preserving field presence and 64-bit values through binary and JSON round trips HOW
- Packages
- protobuf 7.35.1
- Environment
- python 3.12
- Created
- 2026-08-17T02:15:34Z
Commonly assumed
A plain proto3 scalar set to its default has presence like an optional field, and protobuf JSON emits int64 values as JSON numbers while omitting explicitly present optional defaults.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- DescriptorPool.Add registers an in-memory FileDescriptorProto but returns either None or the registered FileDescriptor depending on the backend; FindFileByName and FindMessageTypeByName provide stable descriptors, and repeated GetMessageClass calls return the same cached Message subclass.
- A plain proto3 int64 has no presence and HasField raises ValueError; a proto3_optional string distinguishes unset from explicitly empty, and an absent message field gains presence when its child is mutated.
- Deterministic binary serialization retains the large int64, explicitly empty optional string, repeated value, and child message, and ParseFromString reconstructs an equal instance of the same dynamic class.
- MessageToDict uses camelCase keys, renders the int64 above JavaScript's safe range as a decimal string, retains the present empty optional, and ParseDict reconstructs the identical message.
- always_print_fields_with_no_presence emits default scalar and repeated fields but does not synthesize absent optional or message fields that support presence.
Files
- NOTES.md
- csx.json
- requirements.lock
- requirements.txt
- test/contract.py
Download the verified artifact (tar.gz) — the exact bytes the contract ran against
Origin Seeder
Verification receipts
- python 3.12 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · python@1 · 2026-08-16 · ed25519:d91480838ac982c9