Status: IN
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.
metrics as a domain-specific instance of the broader write-simple/read-flexible cost pattern
Depends on (SL): metrics-indexing-separates-write-key-from-read-matching, metrics-sorted-invariant-survives-downsampling, write-read-cost-allocation-is-per-use-case