Update ERC 7730: update json-schema to 2020-12

[melanciani]

following work on adding a new erc7730 registry using the assets/erc-7730/erc7730-v2.schema.json in ethereum/clear-signing-erc7730-registry#2595

TL;DR

The v2 schema declares draft-07 (line 2), but field uses unevaluatedProperties: false (a draft-2019-09+ keyword) to reject stray keys. Draft-07 ignores that keyword, so field accepts an extra $ref and overlaps the reference branch → any bare { "path": ..., "$ref": ... } field matches two oneOf branches and fails validation. Fix: either declare 2020-12, or add { "not": { "required": ["$ref"] } } to field.

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Details

Symptom. In the https://github.com/ethereum/clear-signing-erc7730-registry repository, check-jsonschema rejects bare references like { "path": "amount", "$ref": "$.display.definitions.x" } with "valid under each of #/$display/reference, #/$format/field" (matches 2 of the fields[] oneOf branches).

Cause. Dialect mismatch: field's unevaluatedProperties: false (line ~640) is meant to reject unknown keys, but it only exists from draft 2019-09 — under the declared draft-07 it's silently ignored, so field tolerates $ref and overlaps reference. The same mismatch overlaps field/fieldGroup for { "path": ..., "fields": [...] } groups (e.g. registry/paraswap/calldata-AugustusSwapper-v6.2.json currently fails too).

Fix options:

1. Root cause: set line 2 to https://json-schema.org/draft/2020-12/schema → activates the existing unevaluatedProperties, fixes both overlaps, keeps strictness. ⚠️ changes whole-file dialect (e.g. $ref-with-siblings, line 546) — needs full-registry re-validation.
2. Targeted, draft-07-safe (applied): add { "not": { "required": ["$ref"] } } to field's allOf. Verified green on the affected file + kyberswap / erc721 / okx / 1inch / lido / threshold; no regression. Doesn't cover the fieldGroup overlap (would need an analogous { "not": { "required": ["fields"] } }).
3. Permissive: oneOf → anyOf (line 419) — one word, fixes both, but weakens validation.

Recommendation: option 1 long-term (the dialect is just mis-declared); option 2 short-term/low-risk.

Open to discussion

[eip-review-bot]

✅ All reviewers have approved.

[melanciani]

I instead moved to solution 1, as discussed

[kuzdogan]

I guess we need to test this by changing the schema on https://github.com/ethereum/clear-signing-erc7730-registry too and running the validation tests against all descriptors @manuelwedler

[melanciani]

@kuzdogan I opened ethereum/clear-signing-erc7730-registry#2624 to update the schema on the registry repo

note:

• I've made Claude run a check on all current schemas in the registry repo and only a single schema fails, but because of a pre-existing unrelated issue : registry/paraswap/calldata-AugustusSwapper-v5.json
• this can be checked by running check-jsonschema --schemafile specs/erc7730-v2.schema.json registry/paraswap/calldata-AugustusSwapper-v5.json in main currently

[eip-review-bot]

All Reviewers Have Approved; Performing Automatic Merge...