[GordonYuanyc]

Part of the ASAPv1-only series: one PR per sketch group, each off main. This one removes the portable Count-Sketch-with-heap format; ASAPv1 (0x0a 0x00) is the only CSHeap format left, and it gets its first golden.

Removed

• message_pack_format::portable::countsketch_topk: CountSketchWithHeap, CsHeapItem, WireHeapItem, SketchlibCSHeap, the sketchlib_cs_heap_* / new_sketchlib_cs_heap / matrix_from_sketchlib_cs_heap / heap_to_wire helpers, CountSketchInnerWire, CountSketchWithHeapWire; crate-root re-exports CountSketchWithHeap, CsHeapItem.
• CSHeap had no proto message and no native shim (native/countsketch_topk.rs is CountL2HH's and goes with that PR).

Added

• Golden csheap_i64_regular_2x4_strkeys (pushed to sketchlib-golden-bytes; submodule bumped): the Count Sketch golden's signed 2x4 matrix plus a k=5 string-keyed heap {alpha: 2^32, beta: 127, delta: 127, gamma: -33}, set directly, never hashed. It pins uint64 and negative heap counts and the tie-by-key order. The test checks both directions and that a plain Count decoder refuses it.
• The ASAPv1 docs no longer state a fixture count; they defer to the golden README's Coverage list (avoids conflicts between the sibling PRs).

Downstream note

• ASAPQuery-backend reads the collector's CS-with-heap msgpack frame through CountMinSketchWithHeap::from_msgpack (the two portable wire shapes were identical). Until the backend moves to ASAPv1, that frame is read with Count-Min semantics (min over signed rows) rather than refused.
• The CS-with-heap heap-delta frame has no ASAPv1 counterpart; no delta codec is removed here.

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, --lib -- countsketch_topk, e2e -- composition wire topk, pbt -- topk_wrappers). The reviewer hand-decoded the new golden byte by byte against spec §3.10. 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Outdated.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.