[GordonYuanyc]

Part of the ASAPv1-only series: one PR per sketch group, each off main. This one removes the portable Count-Min-with-heap format; ASAPv1 (0x03 0x00) is the only CMSHeap format left, and it gets its first goldens.

Draft because of the heap tie-order question below.

Removed

• message_pack_format::portable::countminsketch_topk: CountMinSketchWithHeap (incl. aggregate_topk, merge_refs, from_legacy_matrix, MessagePackCodec), CmsHeapItem, WireHeapItem, SketchlibCMSHeap, the sketchlib_cms_heap_* / new_sketchlib_cms_heap / matrix_from_sketchlib_cms_heap / heap_to_wire helpers, CountMinSketchInnerWire, CountMinSketchWithHeapWire; crate-root re-exports CountMinSketchWithHeap, CmsHeapItem.
• CMSHeap had no proto message and no native shim.

Added

• Five goldens (pushed to sketchlib-golden-bytes; submodule bumped), all built from fixed state, never hashed: cmsheap_i64_regular_2x3_strkeys, cmsheap_i32_fast_2x3_i64keys, cmsheap_i64_regular_2x3_i64tie, cmsheap_i64_regular_2x3_strtie, cmsheap_i64_regular_2x3_empty. The tie fixtures seat entries in two orders and check both encode to the same bytes.
• Spec §3.5/§3.7 now state the key order inside a count tie (see below). The ASAPv1 docs no longer state a fixture count; they defer to the golden README.
• The e2e "Count-Min bound through merge and wire" test now runs on native CMSHeap + ASAPv1.

Open question: heap key order within a count tie

Rust's key_order (shared by CMSHeap, CSHeap, Space-Saving, UnivMon) compares keys as unsigned bits: a signed key by its two's-complement pattern, so ties emit 0, 1, …, MAX, MIN, …, -1; floats by IEEE-754 bits; strings byte-wise. The spec did not say so, and a natural signed sort would have passed the old fixtures. This PR documents the current rule and pins it (…_i64tie, …_strtie) without changing the encoder. Alternative: switch to plain signed order now, before Go mirrors it and before more goldens lock it in.

Downstream

ASAPQuery-backend decodes/writes CMS-with-heap via CountMinSketchWithHeap::{from_msgpack, to_msgpack}; the equivalent native state is CMSHeap<Vector2D<i64>, RegularPath> with string keys. Behaviour differences for callers: CMSHeap::merge panics on a dimension mismatch (the portable type returned Err), and callers must round f64 weights themselves.

Verification (rustc 1.99)

cargo fmt --check; clippy -D warnings for all four CI feature sets; RUSTDOCFLAGS="-D warnings" cargo doc; gen-proto drift clean; filtered tests (asapv1_golden, msgpack_compat, e2e -- composition::, --lib -- countsketch_topk countminsketch_topk, pbt -- heaps::). The reviewer hand-decoded the goldens against spec §3.7. Implemented and reviewed by separate agents; review findings are addressed in the second commit.

🤖 Generated with Claude Code

[GordonYuanyc]

Outdated. ASAPv1 encodings and goldens landed in #232 and #235 against the current spec; removing the legacy formats is redone on current main in #206 and #207.