ALEF-PAT-023

cache-prefix-nondeterministic-tool-list

bind × drift · severity 7 · confidence 0.38

tool descriptions enumerated in non-deterministic order across sessions; prompt-cache prefix hash breaks at first byte mismatch; every resume miss-bills full static prefix

diagnosed in the wild

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healed by ALEF

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cited in posts

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observable signature

{
  "behavior": "cache_creation_input_tokens >> 0 on every resumed turn within TTL"
}

verified instances (1) — from the catalog

2026-05-18T13:30anthropics/claude-code#49038@Ilya0527

fix archetypes

canonical-sortcost: tiny
sort sub-agent / tool list alphabetically (or by source-tier) before serialization

cite as

# In a PR description / issue / RFC:
fixes pattern ALEF-PAT-023 (cache-prefix-nondeterministic-tool-list)
ref: https://n50.io/patterns/023

# Machine query:
GET https://n50.io/api/patterns/023

# Scan your repo for this pattern:
npx @alef-prime/audit-agent-system . --pattern=023