fix(btc): prepend coinbase placeholder leaf in stratum merkle branches - #570
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get_stratum_merkle_branches treated wd->m_hashes[0] as the coinbase
placeholder, but the producers (rpc.cpp, coin/template_builder.hpp) fill
m_hashes as the pure tx-hash list [tx1..txN] with NO coinbase slot. For
any populated (>=1 mempool tx) block this folded tx2 as the first sibling
and dropped tx1, so the stratum header merkle root diverged from the
serialized body -> bad-txnmrklroot rejection. Coinbase-only blocks
(empty m_hashes) early-return {} and collapse to coinbase_txid, so the
bug was latent until the first populated won block.
Fix (fenced to stratum/work_source.cpp, zero coinbase-byte reshape):
- get_stratum_merkle_branches: prepend uint256::ZERO coinbase placeholder
leaf before the branch fold; empty-mempool early return unchanged.
- mining_submit: non-fatal body-vs-header merkle self-check recomputing
compute_merkle_root([coinbase_txid, tx1..txN]) and logging OK/DIVERGENCE
before submit, so the leaf-set class is caught loudly not silently.
Mirrors bch-embedded-steward fenced fix; per-coin isolation preserved.
btc_share_test 39/39 green; make btc exit 0.
Extract the stratum coinbase branch fold into a pure SSOT helper
btc::coin::stratum_merkle_siblings() (template_builder.hpp) and delegate
get_stratum_merkle_branches() to it, so the wire path, the mining_submit
self-check, and tests all exercise one fold.
Add btc_share_test gtest stratum_merkle_branch_test.cpp (CI-bound, 39->42):
- FoldReconstructsBodyRoot: production siblings folded against a coinbase
txid equal compute_merkle_root([coinbase, tx1..txN]) for N in
{0,1,2,3,4,5,7,16} (covers the N=1 case the latent bug corrupted + odd
last-element duplication).
- CoinbaseOnlyHasNoBranches: empty template -> no branches, coinbase IS root.
- PreFixBuilderDivergesOnPopulated: the pre-#570 builder (no leaf-0
placeholder) diverges from the body root on every populated template ->
flip-RED proof the guard is not blind.
No consensus change; test + refactor only, BTC-fenced.
This was referenced Jun 27, 2026
frstrtr
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Jun 28, 2026
…T helper The segwit witness-commitment merkle root was computed inline in work_source.cpp with the coinbase wtxid placeholder (BIP141 32 zero bytes) at leaf 0 -- the same coinbase leaf-0 contract that PR #570 just fixed for the stratum txid merkle, but untested. A populated segwit block that dropped the first tx wtxid (or omitted the placeholder) would be rejected bad-witness-merkle-match by bitcoind, the witness-tree analogue of the #570 bug class, latent because the pool had never connected a populated won block. Extract btc::coin::witness_merkle_root() as the single source of truth for the leaf-0 placeholder + ordering, refactor work_source.cpp to call it (behaviour-identical), and add witness_commitment_merkle_test.cpp (4 KATs, flip-RED proven: removing the placeholder reds the two leaf-0 contract tests). btc_share_test 39 -> 43, BTC-fenced.
frstrtr
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Jul 25, 2026
… (reconstructor slice 4/7) (#838) Port the FRAMING half of p2pool data.py Share.as_block into btc::coin::assemble_won_block: reconstruct the full block header from the share's stored SmallBlockHeader + gentx txid walked up the (segwit-resolved) merkle link via the sealed btc::check_merkle_link, frame [gentx] ++ other_txs with the coinbase at index 0, and emit {bytes, hex} through the live BlockType TX_WITH_WITNESS conditional codec (the NodeRPC::submit_block wire path). BTC divergence from the DGB slice: BTC commits the BIP141 witness root inside the coinbase at gentx-BUILD time (share_check.hpp:2166/:2296), so slices 1-3 hand this framer an already-committed gentx. It therefore does NOT re-inject a witness commitment — doing so would mutate the coinbase, change its txid, invalidate the share-committed header root, and open a second merkle path the sealed merkle family (#570/#574/#579) forbids. The segwit-vs-legacy link selection stays in the caller (slice 5); this framer takes a resolved MerkleLink. Adds a fail-closed body/header guard: body_merkle_root folds [gentx_hash] ++ the non-witness other-tx txids through the sealed btc::coin::compute_merkle_root and assemble_won_block throws rather than emit a bad-txnmrklroot block. On a template_capture miss this passes for empty-link (coinbase-only) shares and correctly refuses the never-valid non-empty-link coinbase-only case. Slice cut off origin/master. btc-tree-only. btc_share_test 82/82 (10 new BtcBlockAssembly KATs, self-derived merkle branches). Co-authored-by: frstrtr <frstrtr@users.noreply.github.com>
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Fixes a latent bad-txnmrklroot in src/impl/btc/stratum/work_source.cpp (cross-coin flag routed from bch-embedded-steward; per-coin isolation preserved — only my BTC file touched).
Bug (producer/consumer m_hashes contract mismatch)
Fix (fenced, zero coinbase-byte reshape)
Smoke
Held for operator tap — I do not self-merge.