Expression Protocol

Canonical wire format for all "expression"-shaped metadata across ObjectStack

(formula fields, predicates, conditions, criteria, visibility rules, seed

dynamic values, …).

The persisted form is \{ dialect, source \} (and, after `objectstack

compilenormalization,{ dialect, ast }`). String-only shorthand is

accepted at input time for developer ergonomics; build emits the canonical

envelope.

Dialects

| dialect | engine | use |

|:---|:---|:---|

| cel | @objectstack/formula (cel-js + ObjectStack stdlib) | formulas, predicates, seed dynamic values |

| js | sandboxed L2 hook bodies (isolated-vm / quickjs) | mapping, hook bodies |

| cron | cron-parser | job schedules |

SQL fragments (analytics joins, partial indexes) are intentionally not

routed through this schema — they stay driver-native because their security

posture and portability story differ.

@see content/docs/concepts/north-star.mdx §8 "No private expression DSL"

TypeScript Usage

import { Expression, ExpressionDialect, ExpressionMeta, Predicate } from '@objectstack/spec/shared';
import type { Expression, ExpressionDialect, ExpressionMeta, Predicate } from '@objectstack/spec/shared';

// Validate data
const result = Expression.parse(data);

Expression

Properties

ExpressionDialect

Allowed Values

• cel
• js
• cron
• template

ExpressionMeta

Properties

Predicate

Properties