feat(xmss): validate XmssConfig fields at construction - #1123
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tcoratger merged 2 commits intoJun 17, 2026
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Add Field(gt=0) positivity constraints to every numeric XmssConfig field, matching the style used by PoseidonParams. Extend the existing model validator to reject an odd LOG_LIFETIME, since the key splits into a top tree and bottom trees that each cover LOG_LIFETIME / 2 levels. Previously a non-positive field or an odd lifetime exponent only failed deep in tree-building with a cryptic error. Now misconfiguration is caught at construction with a clear message. Defaults are unchanged and all three shipped configs still construct. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
# Conflicts: # src/lean_spec/spec/crypto/xmss/constants.py
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Problem
XmssConfigdeclared its numeric fields as bareintwith no positivity constraints, unlikePoseidonParamswhich usesField(gt=0, ...). In addition,LOG_LIFETIMEmust be even (the key splits into a top tree and bottom trees that each coverLOG_LIFETIME / 2levels), but evenness was only enforced deep in tree-building. A misconfiguredXmssConfigtherefore failed late and cryptically.Fix
Field(gt=0)to every logically positive numericXmssConfigfield (LOG_LIFETIME, DIMENSION, BASE, Z, Q, TARGET_SUM, MAX_TRIES, PARAMETER_LENGTH, the field-element lengths, and CAPACITY).LOG_LIFETIMEwith a clear full-sentence message, consistent with the existing decomposition check.LOG_LIFETIME, asserting the full exception message.🤖 Generated with Claude Code