# Spec 13: Self-verifying parallel Shadow Block Producer

Date: 2026-07-19. Chain 2800 (Aere Network mainnet), head ~10,364,611 at build time.

## What was built

A live compliance monitor under `aerenew/shadow-producer/` that re-derives each
canonical chain-2800 block independently and raises a DIVERGENCE ALARM on any
mismatch. It never produces the canonical chain (read-only monitor).

Files:
- `aerenew/shadow-producer/shadow-producer.mjs` - the runner (real, runnable).
- `aerenew/shadow-producer/blockstm-adapter.mjs` - Phase C [MEASURE] scaffold seam
  to the Block-STM parallel executor.
- `aerenew/shadow-producer/README.md` - overview + honest scope + run instructions.
- `aerenew/shadow-producer/package.json` - type:module, scripts, no deps (ethers
  resolved from repo installs via ../conformance/lib.mjs, same as the conformance suite).
- `aerenew/shadow-producer/logs/` - captured live run logs (monitor, selftest, reexec).
- `aerenew/docs/AERE-SHADOW-PRODUCER.md` - architecture + honest-status design doc.

## Phases

- Phase A [FRESH, RUNS LIVE]: recompute QBFT block hash from header fields, assert ==
  canonical blockHash; recover committed seals to quorum against the validator set
  AS OF THAT BLOCK (set grew N=3 -> N=7 over history; per-block set is the honest check).
- Phase B [FRESH, RUNS LIVE]: for a post-EIP-2935 empty block the only state delta is
  one history-ring SSTORE, history[(n-1) % 8191] = blockhash(n-1); re-derive and assert.
  Verifiable for recent blocks (ring holds last 8191; public RPC non-archival).
- Phase C [MEASURE, SCAFFOLD]: full parallel re-execution of the block's txs through the
  Block-STM executor -> full world-state root, diff vs canonical stateRoot. Needs a
  full-state node + forked-Besu parallel EVM; adapter emits an inspectable plan + the
  exact command. Faithful backend = aerenew/parallel/ (253 real blocks re-imported, 0
  mismatch), NOT the toy Rust executor (which proves concurrency correctness only).

## REAL run result (FRESH)

`node shadow-producer.mjs` against https://rpc.aere.network, chain 2800:
- 29 blocks Phase A: block hash re-derived byte-for-byte at EVERY block, spanning the
  whole chain incl. EIP-2935 activation (9,189,161) and base-fee floor fork (10,141,734);
  per-block seal quorum verified (2/3 early N=3, 5/7 current N=7).
- 17 EIP-2935 empty-block state-delta re-derivations verified (Phase B).
- 75 total re-derivation assertions, 0 divergences, exit 0.
- Non-vacuity self-test (`--selftest`): genuine block re-derives (PASS); one-byte
  stateRoot tamper is CAUGHT (PASS). Proves the alarm is not a rubber stamp.
- Phase C (`--reexec`): emits [MEASURE] re-execution plans honestly (no fabricated root).

## Flags / honesty

- Parallel execution is NOT live on L1; canonical chain is sequential Besu. Stated
  everywhere.
- Monitor never produces the canonical chain; a bug in it cannot affect consensus
  (writes nothing consensus reads). Zero-risk on-ramp reasoning documented.
- Consensus stays classical secp256k1 ECDSA QBFT; not touched, not post-quantum.
- Full parallel re-execution against real world state = [MEASURE]; block-fetch +
  hash/state-delta re-derivation = [FRESH] and actually ran.
- No em-dashes / no "--" in prose (only markdown rules, tables, ASCII diagram, CLI in
  code fences). Brand "Aere Network"/"Aere" title case; ticker AERE uppercase.
- One correctness fix during build: initial seal check wrongly used the current N=7
  quorum on historical blocks -> false alarms; fixed to per-block validator set. This
  itself demonstrated the alarm firing, then passing cleanly once correct.
- Reused existing hashing/RLP/seal helpers from aerenew/conformance/lib.mjs (did not
  reinvent). Wired to existing evidence (Block-STM, cross-client determinism, 253-block
  re-import) rather than inventing new numbers.