LarryRuane

PR description working notes — compact spents (draft, not for commit)

Branch: https://github.com/LarryRuane/bitcoin/tree/2026-07-compact-spents

Scratch material for the eventual PR description / commit messages. Grows as we go.

Larry's (human) description

The next section and beyond was written by Claude Code Fable 5, but this section is by ME, an actual human! The overall design is mine, Claude

LarryRuane

╭─── Claude Code v2.1.218 ─────────────────────────────────────────────────────╮
│                                                    │ Tips for getting        │
│             Welcome back Larry Michael!            │ started                 │
│                                                    │ Run /init to create a … │
│                       ▐▛███▜▌                      │ ─────────────────────── │
│                      ▝▜█████▛▘                     │ What's new              │
│                        ▘▘ ▝▝                       │ Changed `/code-review`… │
│   Fable 5 · Claude Max · larryruane@gmail.com's    │ Added screen-reader an… │
│   Organization                                     │ Fixed Windows paths wi… │
│              /sd/g/w/bitcoin-spentdb               │ /release-notes for more │

LarryRuane

diff --git a/src/coins.cpp b/src/coins.cpp
index c403e006c8..2eb673910a 100644
--- a/src/coins.cpp
+++ b/src/coins.cpp
@@ -14,16 +14,24 @@ TRACEPOINT_SEMAPHORE(utxocache, add);
 TRACEPOINT_SEMAPHORE(utxocache, spent);
 TRACEPOINT_SEMAPHORE(utxocache, uncache);
 
+constexpr bool lmr_debug{false};
+

LarryRuane

diff --git a/src/coins.cpp b/src/coins.cpp
index c403e006c8..d2272406ea 100644
--- a/src/coins.cpp
+++ b/src/coins.cpp
@@ -1,384 +1,415 @@
 // Copyright (c) 2012-present The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <coins.h>

LarryRuane

Proposal Summary

I don't have a formal protocol verification background, but I have a proposal related to specification that may aid in creating formal verification, and would be helpful in its own right.

Specifications are usually in the form of a document, but of Bitcoin it's often said that its only protocol (consensus) specification is the Bitcoin Core client software (although it's a de facto, not authoritative specification; the latter doesn't exist). But the difficulty in verifying its correctness, or for readers to understand it, is that it (appropriately) includes so much non-protocol complexity and optimization (both CPU and memory). Also, it's written in C++, which is very efficient, but is not easy to understand.

With that background, my proposal is to write a full consensus protocol specification in the form of working code in its simplest possible form. Human language is amgibuous, but code is precise; it answers all possible question

LarryRuane

#!/usr/bin/env python3
# When two cosecutive blocks have out of order timestamps (the higher height's time
# is less than the lower height's time), print the height of the lower-height block.
#
# prerequisite;
# $ pip3 install python-bitcoinrpc
# or see https://github.com/jgarzik/python-bitcoinrpc

from bitcoinrpc.authproxy import AuthServiceProxy
api = AuthServiceProxy("http://lmr:lmr@127.0.0.1:8332")

LarryRuane

prevector<28u, unsigned char, unsigned int, int>::change_capacity (this=0x555561065eb8, new_capacity=67) at ./prevector.h:191
prevector<28u, unsigned char, unsigned int, int>::resize_uninitialized (this=0x555561065eb8, new_size=67) at ./prevector.h:392
Unserialize_impl<CAutoFile, 28u, unsigned char> (is=..., v=...) at ./serialize.h:782
Unserialize<CAutoFile, 28u, unsigned char> (is=..., v=...) at ./serialize.h:797
UnserializeMany<CAutoFile, prevector<28u, unsigned char, unsigned int, int>&> (s=..., arg=...) at ./serialize.h:1059
SerReadWriteMany<CAutoFile, prevector<28u, unsigned char, unsigned int, int>&> (s=..., ser_action=...) at ./serialize.h:1072
CScript::SerializationOps<CAutoFile, CScript, CSerActionUnserialize> (obj=..., s=..., ser_action=...) at ./script/script.h:435
CScript::Unser<CAutoFile> (s=..., obj=...) at ./script/script.h:435
CScript::Unserialize<CAutoFile> (this=0x555561065eb8, s=...) at ./script/script.h:435
Unserialize<CAutoFile, CScript&> (is=..., a=...) at ./serialize.h:705

LarryRuane

#!/bin/env python3

import sys
from struct import pack

if len(sys.argv) != 2:
    print("usage:", sys.argv[0], "file")
    sys.exit(1)
bitoffset = 0
v = 0

LarryRuane

#!/bin/env python3
import sys
import random

if not len(sys.argv) == 4:
    print("usage:", sys.argv[0], "reps points a-win-%")
    sys.exit(1)

reps = int(sys.argv[1])
points = int(sys.argv[2])

LarryRuane

#!/usr/bin/env python3
import time, sys

from bitcoinrpc.authproxy import AuthServiceProxy
api = AuthServiceProxy("http://lmr:lmr@127.0.0.1:8332")

# infinite retry
def api_retry(*args):
    global api
    while True: