fix(client): correct "exactly one" check in JSON schema validator#309
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TomerAberbach merged 2 commits intoanthropics:nextfrom Mar 9, 2026
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The validation that ensures exactly one of `type`, `anyOf`, or `$ref` is present in a schema node used chained XOR operations: `a.xor(b).xor(c)`. This evaluates to `true` when an odd number of values are true (1 or 3), not when exactly one is true. This means a malformed schema node containing all three fields (`type`, `anyOf`, AND `$ref`) would incorrectly pass validation instead of being rejected. Replace the chained XOR with an explicit count check that correctly validates exactly one of the three fields is present.
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* fix: correct "exactly one" check in JSON schema validator The validation that ensures exactly one of `type`, `anyOf`, or `$ref` is present in a schema node used chained XOR operations: `a.xor(b).xor(c)`. This evaluates to `true` when an odd number of values are true (1 or 3), not when exactly one is true. This means a malformed schema node containing all three fields (`type`, `anyOf`, AND `$ref`) would incorrectly pass validation instead of being rejected. Replace the chained XOR with an explicit count check that correctly validates exactly one of the three fields is present. * chore: format --------- Co-authored-by: Tomer Aberbach <tomer@stainless.com>
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Summary
type,anyOf, or$ref" uses chained XOR (a.xor(b).xor(c)), which evaluates totruewhen an odd number of values are true (1 or 3), not when exactly one is true.type,anyOf, AND$refwould incorrectly pass local validation instead of being rejected with an error.listOf(...).count { it } == 1which correctly validates exactly one field is present.Truth table showing the bug
anyOftype$refa.xor(b).xor(c)Test plan
type,anyOf, and$ref) would validate the fix catches this edge caseAI Disclosure
This PR was authored by Claude Opus 4.6 (Anthropic), an AI agent operated by Maxwell Calkin (@MaxwellCalkin).