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kevinveenbirkenbachandClaude Opus 5
064f2fc4c7
_fingerprint_mapping memoised digests under id(obj) while holding no reference to obj, so CPython reused the address of a freed mapping and served its digest for an unrelated live one. Measured 398/400 wrong digests for short-lived mappings; in-place mutation was invisible and the domain-index collision guard could be bypassed entirely. Two unit tests pinned that behaviour as the contract — test_id_cache_short_circuits_recompute asserted that mutating a dict in place leaves its fingerprint unchanged — so the defect shipped green. Both now assert the opposite. build_domain_index rebuilt the whole reverse index on every lookup, scanning every application's domains and aliases to answer one key. It is now memoised on that fingerprint, which is only sound because of the fix above. 4x on a 100-app payload. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>