docs(asapv1): metadata key names; SetAggregator delta at 08 80

[GordonYuanyc]

Closes #187. Part of #179.

Spec only: docs/asapv1_wire_format.md. Rust and Go code, the API docs and the golden files follow in phase 2.

What the bytes changes reach

• Golden files regenerated (18): the 5 CMSHeap, 1 CSHeap, 3 UnivMon, 5 Hydra, 2 KLL with a seed, and 2 SetAggregator delta files.
• ExponentialHistogram and EHSketchList carry a nested sketch's metadata verbatim, so they change wherever they hold a UnivMon or a seeded KLL.
• Stored or sent downstream:
  • ASAPQuery-backend persists UnivMon summaries as ASAPv1 in its on-disk SketchStore parts.
  • ASAPCollector-public writes seed into KLL frames when its OTAP KLL sketch is configured with a seed.

1. Metadata keys

Sketch	Key today	New key	What it holds
CMSHeap, CSHeap	k	heap_size	how many entries the top-k heap keeps
UnivMon, UnivMon Optimized	layer_size	layers	number of layers
UnivMon	sketch_row, sketch_col	rows, cols	rows and columns of every layer's sketch
UnivMon Optimized	elephant_row, elephant_col, mouse_row, mouse_col	elephant_rows, elephant_cols, mouse_rows, mouse_cols	rows and columns of the elephant-tier and mouse-tier sketches
UnivMon-Q	candidates	heap_size	how many entries each terminal stratum's candidate heap keeps
UnivMon-Q	levels	layers	number of layers
UnivMon-Q	depth, width	rows, top_layer_cols	rows of every layer's sketch; columns of the top layer's sketch
UnivMon-Q	width_halving_period	cols_halving_period	layers between halvings of the column count
Hydra (KLL cells)	counter_k, counter_m, counter_item_type	cell_k, cell_m, cell_item_type	the KLL in each grid cell
Hydra (Count-Min / Count Sketch cells)	counter_rows, counter_cols, counter_type, counter_mode	cell_rows, cell_cols, cell_counter_type, cell_mode	the Count-Min or Count Sketch in each grid cell
Hydra (HLL cells)	counter_precision	cell_precision	the HLL in each grid cell
Hydra (UnivMon cells)	counter_layer_size, counter_sketch_row, counter_sketch_col, counter_heap_size, counter_key_type	cell_layers, cell_rows, cell_cols, cell_heap_size, cell_key_type	the UnivMon in each grid cell
KLL	seed	compaction_seed	seed of the compaction RNG
HLL, Count-Min, Count Sketch, DDSketch	sample_p	admission_rate	probability that an update is admitted

2. kind_id: SetAggregator delta moves from 09 00 to 08 80

A delta's kind_id is its state's kind_id with the top bit of the variant byte set. SetAggregator is 08 00, so its delta is 08 80. 09 00 is retired and never reassigned.

The spec also states that the seedlist in the hash_profile_id value is part of the fixed id, and writes UnivMon-Q's section in layers.

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