Problem

BQIP-0007 weight formula (base_bytes × 4 + witness_bytes × 1) was copied from Bitcoin SegWit but hurts PQC performance because Dilithium5 signatures are ~80x larger than ECDSA.

Numbers

BQIP-0007 gives 46% fewer transactions per block than BQIP-0002.

Root Cause

Bitcoin SegWit: signature ~100 bytes, base ~200 bytes → 4:1 discount helps
BitQuan PQC: signature ~8,000 bytes, base ~110 bytes → 4:1 discount penalizes base while witness still dominates

Solution

Rollback calculate_tx_weight() to BQIP-0002 formula:

weight = base_bytes + sig_count × 384 + witness_bytes × 0.5

• base_bytes × 1 — base data at 1 WU/byte
• sig_count × 384 — fixed cost per signature (algorithm-agnostic)
• witness_bytes × 0.5 — 50% discount on witness data

Scope

• crates/consensus/src/lib.rs — calculate_tx_weight()
• crates/mempool/src/lib.rs — calculate_tx_weight()
• Remove deprecated calculate_block_weight_with_beta() (now redundant)
• Update all test assertions
• BQIP-0007 SegWit infrastructure stays (struct separation, txid/wtxid, witness root)

Files NOT Changed

• transaction.rs — struct already correct
• block.rs — compute_witness_root() already exists
• wire.rs — serialization already correct
• aggregation.rs — BQIP-0008 already correct