ata-validator

A schema with a default anywhere (ata fills defaults without being asked, so it has a preprocess pass) now builds its rich errors where they fail, as other schemas do: the path was closed to schemas with a preprocess pass, though it reads the document validate() has already processed. One required error on a four-field user with a defaulted newsletter went from 313 to 248 ns with its error list read; only the one-pass swap, which replaces validate() itself, stays off for such schemas. Found through the fastest-validator comparison in ata-core/validator-benchmarks (issue #74).

The Node entry warms the engine once the event loop is free: where a validator was built and is still untouched by then (not compiled, no method read off it), one check of a small schema runs, accepted and rejected, so that V8 compiles the generator's functions and the error builders before the first request instead of on it. On a four-field schema with the generator already loaded, a server's first verdict went from 3.1 to 3.4 ms to 0.5 to 0.6, the first error list from 6.7 ms to 0.8, at 1.5 to 2 ms of CPU once. A script that builds and checks in the same tick never runs it, the timer is unref'd, and ATA_NO_WARM=1 turns it off. The browser build has done the same since 1.57.0 (lib/tiering.js); the cold-start benchmarks, which check in the same tick as they build, are unchanged by it. tests/test_node_warm.js holds the conditions.

ata-validator/build exports bunTarget (the schema as a TypeScript type and the .bun.ts module ata build --target bun writes; with tags: true the split into a type with Bun's Schema tags and a residual schema, made for the typed validator the compiler's pull request carried until 2026-10-25) and verify (verifyOne, verifySource, generate), for a build plugin that replaces new Validator(schema) inside a Bun.build({ compile: { aot: true } }) and holds what it wrote against the runtime.

ata verify <glob> holds each schema's compiled module against a runtime Validator built from the schema now: documents made from the schema (--generate, 200 by default, half with one rule broken), the project's sample documents (--samples, JSON or JSON Lines files or a directory), verdicts and error lists compared, a module whose schema hash no longer matches the schema reported stale, a non-zero exit on any disagreement, stale or missing module, --json for machines. The check behind the fixes of 1.59.0 and 1.60.0, as a command a project runs in CI.

A validator the build compiled away (fromCompiled around a module written ahead of time, what @ata-project/unplugin puts in place of new Validator(schema)) carries Standard Schema V1 as the runtime Validator does: the same ~standard object, built by lib/standard-schema.js for both, with the same issues, value and published schema. A compiled validator can now be handed to a form library, a router or an RPC layer that reads ~standard. tests/test_compiled_standard.js compares the two.

toStandaloneModule(schema, { coerceTypes }) and toStandaloneModule(validator) for a validator built with coerceTypes or removeAdditional wrote a module that checked the data as it was, so it rejected { id: "5" } where the validator accepts it. The module now runs the validator's pass over the data before the check, as bundleStandalone does since 1.59.0, and refuses where that pass cannot be written into a module. fastify-ata/standalone builds its files through this call.

bundleStandalone(schemas, { order: true }) hands each validator's errors out in the runtime's order, as toStandaloneModule does with the same option. rjsf's precompiled validator writes its module with bundleStandalone, and its error list showed an additionalProperties error before the properties errors where the runtime validator shows it after. tests/test_aot_order_defaults.js holds 553 bundled groups of the 2020-12 and draft-07 suites to the runtime's errors, in order.

Each validator of a bundle whose schema has a default carries applyDefaults(data), the runtime's defaults pass, as a property, as standalone modules export it. rjsf's precompiled validator can call it to match its runtime validator. tests/test_bundle_preprocess.js compares 8400 generated documents with the runtime: the data afterwards, the verdict and the errors in order.

bundleStandalone left coerceTypes and removeAdditional out without a word, so a bundle built with coerceTypes: true rejected { age: "5" }, which the runtime accepts. Each bundled validator now runs the runtime's pass over the data for those options before it checks, and with useDefaults: true fills defaults the same way. Where the generated pass cannot carry what the runtime would do (coercing the items of an array at the root, for one), bundleStandalone throws instead of writing a module that answers differently. Without these options a bundle checks the data as it is, as before.