fix(core): fix Ajv error discriminator

[harshit078]

What/Why/How?

• This PR addresses issue Respect doesn't resolve complex constraint pattern #2639
• added a utility function remove-discriminators-from-schema which just strips discriminator keywords from schemas
• added this logic before AJV validation

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Testing

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• This PR follows the contributing guide
• All new/updated code is covered by tests
• Core code changed? - Tested with other Redocly products (internal contributions only)
• New package installed? - Tested in different environments (browser/node)
• Documentation update has been considered

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• The security impact of the change has been considered
• Code follows company security practices and guidelines

---

Note

Medium Risk
Changes JSON Schema validation behavior by disabling AJV's discriminator keyword, which may alter how some discriminator-based schemas are validated and could surface new example/schema errors that were previously skipped.

Overview
Fixes AJV validation failures for OpenAPI schemas that use discriminator with composition patterns (e.g. allOf + not) by disabling AJV’s discriminator keyword in both the core AJV validator (packages/core/src/rules/ajv.ts) and Respect’s response schema checker (schema-checker.ts).

Removes the special-case error swallowing in validateExample so discriminator-related AJV errors are now reported instead of silently skipping example validation, and updates/adds tests to assert correct pass/fail behavior for these discriminator schemas.

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🦋 Changeset detected

Latest commit: f2da64e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@redocly/respect-core	Patch
@redocly/openapi-core	Patch
@redocly/cli	Patch

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[DmitryAnansky]

@harshit078
Could you please elaborate on why you believe removing discriminators is a good fix for this issue?
Have you considered any alternative approaches?

[DmitryAnansky]

Please use patch for fixes.

[harshit078]

sure

[harshit078]

@DmitryAnansky sure,
my intent/logic behind creating a function which removes discriminators is because when I researched about OpenAPI discriminator schema I found out that it serves mainly one purpose which is its optimises routing and act as routing shortcut.
The alternatives I considered before submitting PR were -

• Selective stripping: this was more complex than intented and had to have many edge cases
• making discriminator as false : it would have affected globally rather than per schema
• brute force with simple Catch error and retry: same as first point

This is my POV of issue. If you think approach can be better, I am ready to implement it. Thanks :)

[AlbinaBlazhko17]

Thanks @harshit078 for the contribution. You don't need to remove discriminator manually, you can just drop this setting from the Ajv and it will not cause the error. The issue looks more deeply. Could you please investigate the root cause?

[harshit078]

sure, I'll look into it

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[DmitryAnansky]

I’d suggest taking a deeper look into this issue instead of disabling discriminator in Ajv options. It would be worthwhile to review the Ajv implementation and verify how it handles this particular case.