Cast

Overview

Use this skill when a task requires executable CAST DEX operations on Bitcoin with Charms, including order lifecycle management, Scrolls nonce/address derivation, cancellation signatures, partial fills, signing, and transaction verification.

Environment

Required commands:

• bash, curl, jq, envsubst
• charms, bitcoin-cli
• scrolls-nonce, sign-txs, cancel-msg

Required artifacts/services:

• CAST app binary (charms-cast-v0.2.0.wasm or latest v11-compatible CAST build)
• Operator-signed fulfill params payload
• Scrolls API base URL
• prev_txs ancestry data for all spell inputs
• fee funding input UTXO for maker flows (CAST_FUNDING_UTXO)
• v11 spell file (version: 11, tx.*, app_public_inputs)
• separate private-inputs file passed via --private-inputs

Workflow

1. Run preflight checks for your path:

• scripts/check-cast-prereqs.sh maker
• scripts/check-cast-prereqs.sh taker
• scripts/check-cast-prereqs.sh cancel
• scripts/check-cast-prereqs.sh server

2. Follow order-lifecycle for create/check/prove flow.

3. For maker edits, follow cancel-and-replace.

4. For taker fills, follow partial-fulfillment.

5. For signing and broadcast controls, follow signing-and-broadcast.

6. For repeated autonomous execution, follow autotrade-loop.

7. Keep operations deterministic:

• prefer file-backed inputs over inline shell literals
• use dry-run first for mutation steps
• persist artifacts and receipts for every run
• encode tx.coins[*].dest as hex destination bytes (derive via charms util dest --addr ...)

Quick Commands

# Preflight
skills/cast/scripts/check-cast-prereqs.sh maker

# Derive Scrolls nonce + address
skills/cast/scripts/derive-scrolls-address.sh \
  --funding-utxo "<txid:vout>" \
  --output-index 0 \
  --scrolls-base-url "${CAST_SCROLLS_BASE_URL}"

# Migrate legacy CAST howto spell to v11 (split private inputs + convert coin dests)
skills/cast/scripts/cast-migrate-howto-v11.sh \
  --input /Users/christopherdavid/code/charms/cast-releases/docs/howto/03-partial-fulfill.yaml \
  --output-spell ./rendered/03-partial-fulfill.v11.yaml \
  --output-private-inputs ./rendered/03-partial-fulfill.private.v11.yaml

# Check + prove
skills/cast/scripts/cast-spell-check.sh \
  --spell ./rendered/create-order.yaml \
  --private-inputs-file ./rendered/create-order.private-inputs.yaml \
  --app-bin "${CAST_APP_BIN}" \
  --prev-txs-file "${CAST_PREV_TXS_FILE}"
skills/cast/scripts/cast-spell-prove.sh \
  --spell ./rendered/create-order.yaml \
  --private-inputs-file ./rendered/create-order.private-inputs.yaml \
  --app-bin "${CAST_APP_BIN}" \
  --prev-txs-file "${CAST_PREV_TXS_FILE}" \
  --change-address "bc1q..." \
  --mock
skills/cast/scripts/cast-spell-prove.sh \
  --spell ./rendered/create-order.yaml \
  --private-inputs-file ./rendered/create-order.private-inputs.yaml \
  --app-bin "${CAST_APP_BIN}" \
  --prev-txs-file "${CAST_PREV_TXS_FILE}" \
  --change-address "bc1q..."

# Sign + inspect
skills/cast/scripts/cast-sign-and-broadcast.sh --tx-json ./proofs/tx_to_sign.json --dry-run
skills/cast/scripts/cast-show-spell.sh --tx "<spell_tx_hex>"

# Run one automated iteration (safe defaults: mock prove + dry-run sign)
skills/cast/scripts/cast-autotrade-loop.sh \
  --config skills/cast/assets/autotrade-loop.config.example \
  --once

# Run continuous loop (explicitly controlled)
skills/cast/scripts/cast-autotrade-loop.sh \
  --config /absolute/path/to/autotrade.env \
  --interval-seconds 45 \
  --max-iterations 0 \
  --continue-on-error

References

• order-lifecycle
• cancel-and-replace
• partial-fulfillment
• signing-and-broadcast
• autotrade-loop