templatehash-playground

A one-command, reproducible playground for the BIP448 bundle — Taproot-native rebindable transactions (the LNHANCE / CTV+CSFS lineage: OP_INTERNALKEY, OP_CHECKSIGFROMSTACK, OP_TEMPLATEHASH), testable today on the public signet via Bitcoin Inquisition. Learn about the bundle at github.com/bip448.

It's a registry of independent projects, each demoing part of the bundle on signet — ordered oldest-tech-first: LN-Symmetry (eltoo) on Core Lightning, then Ark covenants via OP_TEMPLATEHASH. More plug in as the bundle's other pieces get exercised.

Fastest path: hand it to your AI agent

Paste this repo's URL to your coding agent (Claude Code, Cursor, …) and say "set this up and run the playground." It will read AGENTS.md, install Nix only if your machine needs it, and spin everything up.

Or run it yourself

git clone https://github.com/mvuk/templatehash-playground
cd templatehash-playground
./playground

./playground gets Nix ready — installing it only if necessary (via the Determinate installer), and using per-command flags instead of editing any existing Nix config — then launches the default product: a live status dashboard at http://localhost:4848. Then:

./playground list        # see all products
./playground <name>      # run a specific one
nix run .#default        # if you prefer driving Nix directly
nix run .#node           # (Linux) run a local Bitcoin Inquisition signet node

No Nix, and don't want it? Use the prebuilt image (published by CI):

docker run --rm -it -p 4848:4848 ghcr.io/mvuk/templatehash-playground

Projects

The playground is a registry of independent projects (./playground list), ordered oldest-tech-first:

1. ln-symmetry — LN-Symmetry (eltoo) on Core Lightning (instagibbs' fork), built reproducibly: the eltoo lightningd + its three eltoo subdaemons. eltoo replaces Lightning's penalty transactions with a symmetric latest-state-wins ratchet, using rebindable update+settle txs (ANYPREVOUT, or CSFS+TEMPLATEHASH). (Linux.) nix run .#ln-symmetry shows the node + the runbook for a live signet channel.
2. bark-templatehash — a covenant-enabled bark client (Ark wallet) exercising OP_TEMPLATEHASH.

   Runs the bark client pointed at the hosted Ark server ark.templatehash.com; it does not run a captaind of your own.

Deep dives for both live in docs/. Adding the next project is a PR: copy products/_template/ — see Add your own experiment.

Funding a wallet

A templatehash Ark wallet can currently be funded only by on-chain receive or Lightning receive — not by a faucet VTXO drop. A VTXO belongs to one specific Ark server, and the Second signet faucet's Ark (VTXO) option issues VTXOs on the covenantless Ark server (a different server on the same signet), so those can't land in a templatehash wallet. Fund with one of:

• On-chain: get an address with bark onchain address, request signet coins for it at the faucet (on-chain option), then board into Ark with bark board --all.
• Lightning: mint an invoice with bark lightning invoice "100000 sats" and pay it at the faucet (Lightning option) — it settles into a spendable VTXO.

(Automatic funding, and faucet VTXOs issued on the templatehash Ark server, are phase-2 items.)

Add your own experiment

This is a community playground. Copy products/_template/, edit it, and open a PR — your experiment becomes nix run .#<your-name>. See CONTRIBUTING.md.

Zero-compile

CI (.github/workflows/ci.yml) builds the flake on Linux and macOS on every push and publishes two prebuilt paths, so nobody has to compile:

• a Cachix cache (templatehash-playground.cachix.org), already wired into the flake — nix run / ./playground pull prebuilt binaries, and
• a Docker image at ghcr.io/mvuk/templatehash-playground.

Forking? Point CI at your own cache: create a Cachix cache, add its CACHIX_AUTH_TOKEN secret, and swap the substituter + key in flake.nix's nixConfig.

Status

Two projects, reproducible. ln-symmetry (eltoo Core Lightning — lightningd + eltoo subdaemons, its eltoo settle-tx unit test run in the build) and bark-templatehash (Ark covenant client). A bitcoind-inquisition node (.#node) + nixosModules.inquisition-node (destined for nix-bitcoin). All five bundle opcodes verified active on the live signet (see docs/signet-verification.md). CI (Linux + macOS) + Cachix + Docker + Codespaces zero-compile onramp; live status dashboard for the bark demo.

Next — a fully-automated two-node eltoo channel demo on signet (the CLN integration harness needs its non-NixOS container), faucet auto-funding, and more bundle demos as products/.

License

MIT.