protobuf schema compatibility derived

{
  "input": {
    "body": {
      "after": "syntax = \"proto3\";\npackage shop.v1;\n\nenum Status {\n  UNKNOWN = 0;\n  OPEN = 1;\n  CLOSED = 2;\n}\n\nmessage Order {\n  string order_id = 1;\n  uint64 total_cents = 2;\n  Status status = 3;\n  string tags = 4;\n  int32 discount_cents = 5;\n}\n",
      "before": "syntax = \"proto3\";\npackage shop.v1;\n\nenum Status {\n  STATUS_UNSPECIFIED = 0;\n  OPEN = 1;\n  CLOSED = 2;\n}\n\nmessage Order {\n  string order_id = 1;\n  int64 total_cents = 2;\n  Status status = 3;\n  repeated string tags = 4;\n  string note = 5;\n}\n"
    },
    "type": "http",
    "method": "POST",
    "bodyType": "json"
  },
  "output": {
    "type": "json",
    "example": {
      "limits": {
        "maxFindings": 500,
        "maxSdlBytes": 262144,
        "maxVersions": 25,
        "maxAvroBytes": 262144,
        "maxConsumers": 50,
        "maxProtoBytes": 262144,
        "maxPathsPerConsumer": 200
      },
      "passed": false,
      "complete": true,
      "findings": [
        {
          "code": "VALUE_SEMANTICS_CHANGED",
          "field": "total_cents",
          "detail": "shop.v1.Order.total_cents = 2 went from int64 to uint64, which share the varint wire type, so old bytes decode without error and a value above the signed maximum reads as negative, or a negative value...",
          "number": 2,
          "message": "shop.v1.Order"
        },
        {
          "code": "CARDINALITY_CHANGED",
          "field": "tags",
          "detail": "shop.v1.Order.tags = 4 went from repeated to singular. The bytes still parse and the decoded shape changes, so a reader keeps only the last value or sees a one-element list.",
          "number": 4,
          "message": "shop.v1.Order"
        },
        {
          "code": "FIELD_RENAMED",
          "field": "discount_cents",
          "detail": "shop.v1.Order field 5 went from note to discount_cents. The wire format is unchanged because the number is the identity, and every generated accessor, JSON name and text-format name changes.",
          "number": 5,
          "message": "shop.v1.Order"
        }
      ],
      "compatible": false,
      "request_id": "example-request",
      "service_id": "protobuf_schema_compatibility",
      "assumptions": [
        "The field number is the identity, as protobuf defines it, and the name is not. A rename is therefore reported as wire-compatible and a source break, and reusing a number is reported as a silent reinte...",
        "Removing a field is only safe when the number cannot come back, so a removal without a matching reserved entry is a finding even though the removal itself parses.",
        "A type this file does not define, typically an imported one, is reported as not compared rather than assumed compatible. Services, extensions and groups are recognised and listed as not modelled."
      ],
      "limitations": [
        "The two .proto sources supplied, as a documented subset: messages, enums, fields, oneofs, maps and reserved ranges. Imports are recorded and not followed.",
        "compatible is true only when everything was compared and nothing changed in a way that affects a reader, a writer or generated code."
      ],
      "observed_at": "2026-10-02T00:00:00.000Z",
      "after_syntax": "proto3",
      "not_examined": [],
      "before_syntax": "proto3",
      "finding_count": 6,
      "service_version": "1.0.0",
      "after_enum_count": 1,
      "findings_by_code": {
        "FIELD_RENAMED": 1,
        "WIRE_TYPE_CHANGED": 1,
        "ENUM_VALUE_RENAMED": 1,
        "CARDINALITY_CHANGED": 1,
        "ENUM_ZERO_VALUE_CHANGED": 1,
        "VALUE_SEMANTICS_CHANGED": 1
      },
      "before_enum_count": 1,
      "after_message_count": 1,
      "before_message_count": 1
    }
  }
}