Node parameters and environment

`payment_node` parameters

Parameter	Default	Description
`backend`	`self_custody`	Where keys live and how transactions are sent. `self_custody` keeps an encrypted key on the robot.
`chain`	`base-sepolia`	`base-sepolia` for testnet, `base` for mainnet
`signature_exchange`	off	Publish and consume escrow signatures on `/escrow/signatures`
`max_per_transaction`	`"10"`	Largest single payment, in USDC
`max_per_window`	`"50"`	Total spend allowed per rolling window, in USDC
`window_seconds`	`3600`	Rolling window length

Caps are strings, so pass them quoted: -p max_per_transaction:="'0.10'".

The passphrase is deliberately not a parameter. Parameters can be listed by any node on the graph.

Variable	Purpose
`ROBOPAY_PASSPHRASE_FILE`	Path to a file holding the wallet passphrase. Must be mode `0600` or the node refuses it.
`ROBOPAY_PASSPHRASE`	Passphrase in the environment. Convenient for development, weaker than a file.
`BASE_SEPOLIA_RPC_URL`	Your own Base Sepolia RPC endpoint. Public endpoint used if unset.
`BASE_MAINNET_RPC_URL`	Your own Base mainnet RPC endpoint. Public endpoint used if unset.
`ROBOPAY_LIVE_TESTS`	Enables tests that talk to a real network

If neither passphrase variable is set, the node prompts on the terminal with input hidden.

Everything robopay stores lives under ~/.robopay/:

Path	Contents
`wallets/<address>.json`	Encrypted private key (scrypt + Fernet), mode `0600`
`idempotency.db`	Payment lifecycle records
`escrows.db`	Escrows opened by this robot, for automatic refunds

Back up the wallet files together with their passphrases. Without both, funds in that wallet are unrecoverable.