Charms

Overview

Integrate and operate Charms for programmable Bitcoin assets. Use this skill when a task requires Charms app development, spell creation and proof generation, commit and spell transaction submission, spell inspection on existing transactions, wallet charm inventory, or API and wallet integration.

Environment

• Requires bash, curl, and jq.
• Requires charms CLI.
• For app development, requires Rust and wasm32-wasip1 target.
• For Bitcoin casting and wallet flows, requires bitcoin-cli connected to a node (testnet4 for quick iteration).

Use this skill for concrete implementation and operations, not generic protocol theory.

Workflow

1. Pick the execution path first:

• App and spell lifecycle (new app, build, verify key, check, prove, submit).
• Spell schema and validation debugging.
• Wallet and API integration (wallet list, tx show-spell, server endpoint).

2. Run preflight checks:

• scripts/check-charms-prereqs.sh app
• scripts/check-charms-prereqs.sh spell
• scripts/check-charms-prereqs.sh wallet
• scripts/check-charms-prereqs.sh server

3. For app and spell operations, follow app-and-spell-workflow:

• Scaffold app with charms app new.
• Build and derive app verification key.
• Validate spells with charms spell check.
• Produce package-ready transactions with charms spell prove.

4. For schema and validation issues, use spell-format-and-validation:

• Confirm app identifiers and VKs.
• Confirm ins and outs line up with transaction reality.
• Keep private inputs off-chain and pass them through the private input file path.

5. For wallet and API surfaces, use wallet-and-server-integration:

• Inspect wallets for charm-bearing outputs.
• Decode spell content from known transactions.
• Run charms server and call /spells/prove in JSON or CBOR mode.

6. Apply execution safety constraints:

• Use low-value UTXOs and testnet4 while iterating.
• Never submit package transactions before validating both commit and spell tx hex.
• Keep prover and wallet secrets out of logs and source control.

Quick Commands

# App scaffold and build
charms app new my-token
cd my-token
app_bin="$(charms app build)"
charms app vk "$app_bin"

# Spell validation and proving
cat ./spells/mint-nft.yaml | envsubst | charms spell check --app-bins="$app_bin" --prev-txs="$prev_txs"
cat ./spells/mint-nft.yaml | envsubst | charms spell prove --app-bins="$app_bin" --prev-txs="$prev_txs" --funding-utxo="$funding_utxo" --funding-utxo-value="$funding_utxo_value" --change-address="$change_address"

# Wallet and tx inspection
charms wallet list --json
charms tx show-spell --chain bitcoin --tx "$tx_hex" --json

# API server
charms server --ip 0.0.0.0 --port 17784

Reference Files

• app-and-spell-workflow: end-to-end app scaffold, check, prove, sign, and package submission.
• spell-format-and-validation: spell fields, app mapping, proof and version checks, and frequent failure modes.
• wallet-and-server-integration: wallet parsing, tx inspection, API server usage, and wallet UI integration path.