{"id":"metrics-instantiates-write-read-cost-pattern","text":"Metrics is a concrete instantiation of the codebase's per-use-case write-read cost allocation: frozen tag sets and sorted insertion keep the write path structurally simple (O(log n) per point), while subset matching and multi-tier downsampling absorb read-path flexibility and cost — the module explicitly allocates complexity to reads for query expressiveness.","truth_value":"IN","source":"","source_url":"","source_hash":"","justifications":[{"type":"SL","antecedents":["metrics-indexing-separates-write-key-from-read-matching","metrics-sorted-invariant-survives-downsampling","write-read-cost-allocation-is-per-use-case"],"outlist":[],"label":"metrics as a domain-specific instance of the broader write-simple/read-flexible cost pattern"}],"dependents":["metrics-is-complete-write-read-exemplar"],"metadata":{"last_reviewed":"2026-06-06T06:26:57","review_result":"pass"},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"metrics-instantiates-write-read-cost-pattern","truth_value":"IN","reason":"SL justification valid","antecedents":["metrics-indexing-separates-write-key-from-read-matching","metrics-sorted-invariant-survives-downsampling","write-read-cost-allocation-is-per-use-case"],"label":"metrics as a domain-specific instance of the broader write-simple/read-flexible cost pattern"},{"node":"metrics-indexing-separates-write-key-from-read-matching","truth_value":"IN","reason":"SL justification valid","antecedents":["metrics-series-keyed-by-frozen-tags","metrics-tag-matching-is-subset"],"label":"Frozen keys guarantee stable identity for storage while subset matching decouples query expressiveness from key structure"},{"node":"metrics-series-keyed-by-frozen-tags","truth_value":"IN","reason":"premise"},{"node":"metrics-tag-matching-is-subset","truth_value":"IN","reason":"premise"},{"node":"metrics-sorted-invariant-survives-downsampling","truth_value":"IN","reason":"SL justification valid","antecedents":["metrics-series-sorted-invariant","metrics-downsample-two-tier"],"label":"Sorted order is re-established after downsampling, not merely assumed to survive aggregation"},{"node":"metrics-series-sorted-invariant","truth_value":"IN","reason":"premise"},{"node":"metrics-downsample-two-tier","truth_value":"IN","reason":"premise"},{"node":"write-read-cost-allocation-is-per-use-case","truth_value":"IN","reason":"SL justification valid","antecedents":["eager-rebuild-trades-write-cost-for-derived-consistency","lazy-read-time-evaluation-trades-write-simplicity-for-read-cost"],"label":"These two depth-1 conclusions represent opposite strategies for the same problem (when to compute derived state), revealing a spectrum rather than a convention"},{"node":"eager-rebuild-trades-write-cost-for-derived-consistency","truth_value":"IN","reason":"SL justification valid","antecedents":["autocomplete-cache-consistency","leaderboard-update-by-remove-reinsert"],"label":"autocomplete rebuilds top_k_cache for all ancestor nodes on every trie mutation; leaderboard removes and reinserts entries on score update — both choose O(mutation) rebuild over eventual consistency of derived structures"},{"node":"autocomplete-cache-consistency","truth_value":"IN","reason":"premise"},{"node":"leaderboard-update-by-remove-reinsert","truth_value":"IN","reason":"premise"},{"node":"lazy-read-time-evaluation-trades-write-simplicity-for-read-cost","truth_value":"IN","reason":"SL justification valid","antecedents":["autocomplete-decay-is-read-time","url-shortener-expiration-lazy","payment-balance-never-cached"],"label":"Three independent systems chose lazy evaluation, suggesting write-simplicity is the dominant concern in pedagogical implementations"},{"node":"autocomplete-decay-is-read-time","truth_value":"IN","reason":"premise"},{"node":"url-shortener-expiration-lazy","truth_value":"IN","reason":"premise"},{"node":"payment-balance-never-cached","truth_value":"IN","reason":"premise"}]}}