For AI agents: the complete documentation index is available at https://flow.jig.md/llms.txt, the full documentation bundle is available at https://flow.jig.md/llms-full.txt, and this page is available as Markdown at https://flow.jig.md/spec/json-values.md.
FLOW
DocumentationSpecificationPrerelease

#FLOW JSON/0 value model

View Markdown

FLOW uses JSON as a bounded cross-language value format. JSON/0 fixes the parts which ordinary host parsers otherwise disagree about; it is not a new serialization syntax.

It applies to protocol frames, settings, inputs, results, schemas, and descriptors unless a particular protocol or value seam states a lower limit.

#Syntax and strings

JSON/0 is RFC 8259 JSON encoded as UTF-8, with no BOM. Parsers reject duplicate object member names before constructing an object. Strings and member names contain Unicode scalar values only; literal or escaped lone surrogates are invalid. Host-language object prototypes and magic property names have no semantic role.

#Numbers

A number is a finite IEEE 754 binary64 value obtained by correctly rounded decimal conversion using round-to-nearest, ties-to-even. NaN and infinities are not values. A number whose resulting value is mathematically integral must be within [-9007199254740991, 9007199254740991]; larger integral quantities use strings. Negative zero is admitted but equals and canonicalizes as zero.

Consequently 1 and 1.0 are the same JSON/0 value, while the integer token 9007199254740993 is invalid instead of being preserved by Python and rounded by JavaScript.

#Equality and canonical bytes

Equality is recursive:

  • null, booleans, and strings compare by exact value;
  • numbers compare by their binary64 numeric value, with -0 equal to 0;
  • arrays compare by length and corresponding values in order;
  • objects compare by the same exact member-name set and equal corresponding values, independent of source member order.

RFC 8785 serializes an already valid JSON/0 value for digests and operation identities. Canonicalization does not repair duplicate keys, invalid Unicode, an out-of-domain number, or an oversized value; those fail first.

#Absolute value limits

One encoded JSON/0 document or protocol frame has these inclusive maxima:

UTF-8 encoded bytes                   16,777,216
value depth (root is 1)                       128
total value nodes, including root         262,144
members in one object                      65,536
items in one array                         65,536
UTF-8 bytes in one string value         8,388,608
UTF-8 bytes in one member name              1,024
bytes in one number token                      128

Every array item and object member value is one child value node; member names are not additional nodes. A narrower protocol, contract, or schema may impose a smaller bound only when that bound is fixed and known before the value is produced or accepted. It may never accept a value above the JSON/0 absolute maxima while claiming JSON/0 conformance.

JSON/0 does not define a universal wire error name. The protocol or value seam reports the applicable failure—for example a fatal framing error, JSON-RPC invalid params, INVALID_INPUT, INVALID_RESULT, or SCHEMA_INVALID_JSON.