soft3/bbg/audit/dimension-version-2-2026-10-15.md

bbg audit launch audit cyber
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dimension version 2 — the bostrom genesis root unblocked

Date: 2026-10-15. Scope: bbg feat/dimension-chunks (PR #41, on master after #40) and its integration onto the 0.3 line int/genesis-dims (PR #42), with soft3 genesis/dimension-v2 on top of soft3 #183 (soft3 genesis build). Tracker: cyber/launch.md rows 14 (genesis bijective with the snapshot) and 43 (block cost). Prior finding: soft3 #183 — the bostrom state root was root_blocked: lens/brakedown MAX_VARIABLES = 20 caps a v1 dimension at 2^20 field elements and bostrom's particles dimension needed 2^27, files / balances / axons 2^25, signals 2^24; two engine inflations made it worse.

what changed

  1. root version 2 is the default. The dimension leaf is the keyed-trie root (rs/src/trie.rs, #40). There is no size cap: a trie grows by one leaf and ≤ one branch per record. v1 (flat Brakedown polynomial) stays opt-in for the zheng look argument and the state certificates.
  2. injective leaves. Keys enter the leaf chain as eight 32-bit limbs, every u64 field as two 32-bit limbs (dim::u64_limbs, dim::bytes32_limbs — the same functions the 0.3 line's DIMENSION_VERSION = 2 serialization uses). One Goldilocks limb per u64 is not injective (v and v − p collide) and a raw 64-bit key limb ≥ p was craftable.
  3. a link without conviction writes topology only. BbgState::insert with amount = 0 touches axons_out, axons_in and the reverse edge map and nothing else: no axon-particle, no target energy, no neuron focus, no balance row. A genesis replay is all such links.
  4. a zero balance is an absent row. balances[k] reaching 0 is removed.

Spec: specs/state.md § root versions → "dimension version 2", § dimension commitment v2.

the two inflations, measured on the snapshots

Counts from soft3 genesis build (bbg: lines of its report), before = soft3 #183's run on the 0.3 line, after = int/genesis-dims:

chain dimension before after why
pussy particles 16,271 content + axon-particles per link 16,271 rule 3
pussy balances one zero row per link endpoint + 442 real 442 rules 3–4
bostrom particles 6,086,630 (3,143,650 content + axon-particles) 3,143,650 rule 3
bostrom balances 3,200,435 (56,785 real) 56,785 rules 3–4

genesis build, end to end

soft3 genesis build --chain <chain> --snapshot ~/cyber/<repo>/snapshot --out /tmp/gen/<chain> (cache ~/cyber/.cache/snapshots/<chain>), release build, M4 Max, one thread; peak memory = /usr/bin/time -l. verify --root re-loads the manifest and recomputes the root.

chain links genesis hash state root (v2) wall peak memory verify --root
pussy 29,112 4d703ecc1d618eb4921de62d8bca4326db8b7cb9140dced576278e1d9eec70ef 47fcbd67ce96ecf965b77527a1fc0a01982f0ce7b76b275240d315fe8ce8d924 10.7 s 74 MB clean
bostrom 2,949,732 d0965ed10f0fe29c33467d352e9ae5c66b59cd4ff04169fe143b9a06800c0fd2 7cbac3268e12e6d954ec477e6a2039b5697d4ba8bda85ca2a1c59e42fa8d025a 1,790 s (state load + root 1,750 s; the bbg link replay shared the machine for the first 20 min) 8.57 GB not run (a second 30-minute load; the pussy verify is clean and the loader is deterministic by #183's two-build check)

Before: pussy 8339b4ad… / root f5b10b87… (v1 on the 0.3 line, with the inflations); bostrom hash da45937f…, root blocked, 104 s, 5.2 GB (soft3 audit/genesis-2026-10-15.md). The genesis hash moves because the manifest carries state_counts / state_fields, which the deflation changed; the root moves because the derivation is v2. The new chain starts fresh, so nothing deployed depends on the old values. No conformance .snap files exist to bless (soft3/conformance is a scaffold).

bbg alone: the bostrom link stream through BbgState::insert

rs/examples/replay_pussy.rs /tmp/bostrom-cyberlinks.csv v2 0 — the 2,949,732 links as one-link signals with amount = 0, one block per source height, root at every block edge (383,503 blocks), no genesis tables:

links wall µs/link peak memory
2,949,732 1,168.6 s 396 4.74 GB (the CSV rows stay resident)

Per-10k cost: 587 µs at 500k, 328 µs at 1.5M, 353 µs at 2.5M — flat; the last 400k links ran at ≈ 1.2–1.6 ms while the genesis build shared the machine. max_degree 30,439 (a hub append is O(log degree)).

what this does not do

  • The zheng look argument and the state certificates still open v1 Brakedown cells; a read against a v2 root needs a trie-path opening in zheng. Tests that exercise them pin RootVersion::V1 on small states.
  • The per-neuron nonce field (soft3 feat/chain-kernel → bbg feat/chain-dims) was not on origin when this was written; it belongs in the same dimension version — add it to NeuronRecord::leaf_vals and dim_entries, re-pin tests/root_vectors.rs.
  • Storage is untouched: the tries live in memory next to the maps.

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