User activated sidechains: Bitcoin's rules beside a Bitcoin-family chain, blocks valid because they are signed, no subsidy, every coin a coin locked on the parent, and the rules carried as signed documents each node chooses to adopt. Signers order blocks; users enforce the rules.
- SPEC.md: the protocol, draft 0.0.5.
- paper/: the white paper, sidestr: User-Activated Sidechains, draft 27 September 2026 (Markdown, PDF).
- The first chain is the txbt4 siding, a chain beside the BLAKE2b testnet4 that keeps making blocks while the parent waits at its retarget. Level 1, one signer, worthless coins.
The sibling of datstr: the same engine, the same documents, the same rule that everything a verifier does runs in a browser tab.
The reference implementation, on the same engine as datstr and blaketestnode:
siding/chain.json the txbt4 siding: id, parent, challenge, the four genesis pegs, powLimit, prefix
chains/<name>/ every other chain, one document each (`siding new` writes them)
siding/lib/overlay.mjs the network overlay, the block-signature rule, the claim and burn rules (SPEC 3, 4, 6, 7)
siding/lib/announce.mjs the tip announcement: a chain found by its id alone (SPEC 11)
siding/lib/parent.mjs the parent over RPC: peg-ins scanned and claimed, burns paid from the peg wallet
siding/bin/siding.mjs new | key | genesis | produce | sync | send | faucet
node siding/bin/siding.mjs new --name X --prefix Y a whole chain: document, key, genesis, the lines to run it
node siding/bin/siding.mjs produce --chain C --dir D blocks on an interval, sooner with transactions
node siding/bin/siding.mjs sync --url URL --dir D validate a producer's chain, no key needed
Needs checkouts of bitcoin-desktop/schema (SCHEMA) and bitcoin-blake/blaketestnode (BLAKETESTNODE, the block-file node lib/chain.mjs builds on). The genesis is deterministic: the same
chain document gives the same block 0, byte for byte.
Around it: the explorer and wallet
take ?chain=<id> and find the chain from its announcement; the directory
lists every chain that has announced itself.
Picking this up as a developer or an agent: start with siding/README.md, the map of the reference implementation and what is not yet built.