chore(schemas): migrate to JSON Schema 2020-12

[ucekmez]

Summary

PR 20 of a stacked series. Base is #111. Not for merge without review.

Every schema declared http://json-schema.org/draft-07/schema#, while @eep-dev/setup-cli emits openapi: "3.1.0" documents that $ref those files.

OpenAPI 3.1's schema dialect is JSON Schema 2020-12. So generated descriptions referenced draft-07 schemas from a 2020-12 context — a dialect mismatch strict OpenAPI 3.1 tooling trips on, and one the canonical openapi.yaml from #109 inherits.

Migrating also unblocks the roadmap's "Schema → TypeScript / Pydantic codegen with a CI drift gate" item: most modern codegen targets 2020-12.

The migration is mechanical — and I checked the tree first

Rather than assuming, I enumerated the keywords that actually differ between the dialects:

Keyword	Occurrences	Action
definitions	8	→ $defs, plus every #/definitions/ pointer
array-form items	0	no prefixItems conversion needed
dependencies	0	—
additionalItems	0	—
exclusiveMinimum	3	already numeric form; unchanged between dialects

definitions is the one that matters silently. A file left using the old keyword validates as an unknown annotation rather than failing — its subschemas just stop being reachable, with no error. There's a new test pinning that neither "definitions" nor #/definitions/ reappears.

Validator changes

Ajv's default export only understands draft-07, so every validator construction moves to the ajv/dist/2020 build:

• tests/test_schemas.test.ts, tests/conformance-fixtures.test.ts, tests/bench.test.ts
• @eep-dev/compliance-cli/src/schemas.ts

Assertions that pinned the old dialect are updated rather than deleted — including the cross-impl Python one.

Scope

• Spec / schema only
• TypeScript package(s)
• Python package(s)
• Tests / CI
• Docs / examples

Checklist

• I read CONTRIBUTING.md and CODE_OF_CONDUCT.md.
• Tests added or updated where appropriate.
• Breaking change? No property, constraint or $id changed, so every document that validated before still validates. The $schema value changed on all 24 files, which downstream tooling pinned to draft-07 will notice — worth a CHANGELOG line. Consumers using Ajv will need the ajv/dist/2020 build, as this PR does internally.
• Documentation updated for user-visible behavior.

Verification

Suite	Result
tests/	200 passed
@eep-dev/gates	491 passed
@eep-dev/middleware	259 passed
@eep-dev/compliance-cli	73 passed
@eep-dev/discovery	42 passed
@eep-dev/setup-cli	44 passed
tests/cross-impl/	56 passed, 3 skipped
compliance-cli --fixtures	26 vectors, 0 failed
codegen-schema-types --check	no drift
check-draft-schema-parity	✓
openapi-route-parity	✓

A repo-wide grep for draft-07 now returns only the explanatory comments about why the ajv/dist/2020 build is required.

Notes for reviewers

This deliberately sits near the end of the stack. It churns all 24 schemas, so putting it earlier would have made every subsequent schema-touching PR rebase through a dialect migration. Everything that adds properties (#100, #106, #107, #110, #111) lands first.

$id values are untouched — they still read https://eep.dev/schemas/v0.1/…. Changing them would be a genuine break for anyone resolving schemas by $id, and the dialect change does not require it.

Python side needs no change: nothing in the repo validates with jsonschema; the Python fixture harness compares recorded outcomes rather than compiling schemas. Worth knowing if that changes.

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