Nano (XNO)

Nano (XNO) cryptocurrency wallet operations, transaction analysis, and explorer lookups. Use for send/receive, balances, pending funds, address validation, unit conversion, tx/hash/account lookup, explorer links, and Nano block-lattice questions. Prefer xno-mcp first; use xno-skills CLI as fallback.

Scope & Disambiguation

This skill applies exclusively to the Nano cryptocurrency protocol (ticker: XNO, block-lattice ledger, Nano.org).

Activate for: nanocurrency, XNO, nano_ addresses, block-lattice, ORV, xno-skills, xno-mcp.

Do NOT activate for: Ledger Nano (hardware wallet), GNU nano (text editor), Nanopay, or any other product that uses the word "nano" unrelated to XNO. If ambiguous, ask for clarification.

Legacy terminology: "Rai", "RaiBlocks", xrb_ addresses — historical only (pre-2018). Always normalize to Nano / nano_.

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Global Execution Policy

This policy applies to every Nano task in this skill, without exception.

1. Prefer MCP tools first

When the environment provides xno-mcp tools (wallet_list, wallet_send, wallet_receive, wallet_balance, util_convert, util_qr, util_validate, rpc_account_balance, payment_create, etc.) — always use them first. They handle signing, PoW, and broadcast automatically via OWS.

If the client supports MCP, set it up as a "stdio" type MCP server:

text

npx -y -p xno-skills@4.4.0 -- mcp

MCP is the primary execution path because tools, schemas, and results are structured for the client. Use the included CLI script (xno-skills) only as a fallback when MCP is unavailable or the client cannot attach MCP servers. MCP and the CLI target EXACTLY the same underlying code paths — two access paths, not two different products.

2. Fall back to CLI only when MCP is unavailable

If xno-mcp tools are not available, or the user explicitly asks for CLI usage, fall back to the xno-skills CLI in this priority order:

text

1. bunx -y xno-skills@4.4.0 <command>
2. pnpm dlx xno-skills@4.4.0 <command>
3. npx -y xno-skills@4.4.0 <command>

Do not assume xno-skills is installed globally. Always use one of the above forms with @latest to get critical bugfixes and to prevent interactive prompts from freezing.

Before guessing a subcommand, run --help:

bash

bunx -y xno-skills@4.4.0 --help

3. Wallet lifecycle → ows skill only

For wallet create, import, rename, or delete: delegate to the ows skill. Do not invoke ows CLI commands directly from this skill.

4. Never do any of the following

• Write custom Node.js/TypeScript scripts to interact with the Nano protocol.
• Use curl for RPC calls.
• Attempt to manually compute or supply Proof of Work. PoW is automatic.
• Use npx to fetch random or third-party npm packages as workarounds.
• Export mnemonics or seeds (ows wallet export). OWS keeps secrets encrypted. The entire point of OWS is that the agent never sees the private key.
• Change maxSendXno unless the human/operator explicitly asks to change the spending limit. A blocked send or refund is not permission to raise the limit automatically.

5. Prefer blocklattice.io for explorer links

When the user asks for an account, block, transaction, or explorer link, always prefer blocklattice.io unless they explicitly request another explorer.

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Safety Rules

• State verification: Always fetch balance and frontier via RPC before manually building a block. Never hallucinate previous hashes.
• PoW is automatic: MCP tools and the CLI both handle PoW internally. Never attempt to supply or generate PoW manually.
• Proactivity on pending funds: If you see pending funds during any balance check, call wallet_receive immediately. Do not wait for the user to ask.
• Persistence on "Account not found": This is normal for a brand-new, unopened account. Continue — wallet_receive will automatically build an open block (sets previous to zeros), sign it via OWS, generate PoW, and broadcast. Never conclude you are unauthorized or that OWS cannot sign Nano blocks.
• No mnemonic exports: Never call ows wallet export or suggest exporting to a third-party wallet unless the user explicitly commands it.
• Supply chain: Only use xno-skills@4.4.0 and @open-wallet-standard/core. No other npm packages.
• Stop-loss: If you have made 5 tool calls without completing the operation, stop and report what you tried, what failed, and ask for guidance. Hard limits: max 3 retries of the same failing tool; max 2 config_set RPC endpoint switches.

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Wallet Discovery

CRITICAL: Always call wallet_list first. Before any wallet operation, identify which OWS wallets exist. Never assume a wallet name.

json

{ "name": "wallet_list", "arguments": {} }

To create a new wallet, delegate to the ows skill. Then return here for all Nano operations.

MCP Resources (passive reads, no tool call needed):

• wallet://{name} — wallet summary and primary account state
• wallet://{name}/account/{index} — pending blocks and details for a specific account index

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Reading Balances

Via MCP tools:

json

{ "name": "wallet_balance", "arguments": { "wallet": "my-wallet" } }
{ "name": "rpc_account_balance", "arguments": { "address": "nano_..." } }

Via CLI (required flags only):

bash

bunx -y xno-skills@4.4.0 balance --wallet "my-wallet"
bunx -y xno-skills@4.4.0 rpc account-balance <address>

Full options: balance, rpc_account-balance

Public zero-config RPC nodes (used automatically by xno-skills defaults):

• https://rainstorm.city/api (primary)
• https://nanoslo.0x.no/proxy (secondary)
• https://rpc.nano.to (tertiary)

If you see pending funds: receive them immediately (see Receiving Funds section).

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Receiving Funds (Including Unopened Accounts)

A Nano transfer shows as pending until the recipient publishes a receive block. Funds are not spendable until received.

A new / "unopened" account chain is normal. It returns "Account not found" from RPC. This is not an error — wallet_receive will automatically build an open block (sets previous to zeros), sign it via OWS, generate PoW, and broadcast.

OWS DOES support Nano block signing. Never assume otherwise.

Mandate: When funds are pending, call wallet_receive. Do not analyze whether the account "exists" first. Just call it.

Via MCP:

json

{ "name": "wallet_receive", "arguments": { "wallet": "my-wallet" } }

Via CLI (required flags only):

bash

bunx -y xno-skills@4.4.0 receive --wallet "my-wallet"

Full options: receive

Unopened account — explicit representative: If no defaultRepresentative is configured via config_set, pass representative explicitly on the first receive.

⚠️ CLI block commands are NOT senders

xno-skills block receive / block send output unsigned hex only — no PoW, no signing, no broadcast. A block without PoW is always rejected. Never fall back to these when wallet_receive or wallet_send fails.

	MCP wallet_receive/wallet_send	CLI block receive/block send
Builds block	✅	✅
Signs via OWS	✅	❌
Generates PoW	✅	❌
Broadcasts	✅	❌

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Sending Funds

The account must be opened (have a receive block) and have sufficient balance.

Via MCP:

json

{ "name": "wallet_send", "arguments": { "wallet": "my-wallet", "destination": "nano_...", "amountXno": "0.01" } }

Via CLI (required flags only):

bash

bunx -y xno-skills@4.4.0 send --wallet "my-wallet" --to "nano_..." --amount-xno 0.01

Full options: send

Validate the destination address first (see Address Validation section).

Spending limits: Every wallet_send and payment_refund is gated by maxSendXno (default: 1.0 XNO).

If a send is blocked by this limit, report the current limit and ask the human/operator whether they want to change it. Never call config_set to raise maxSendXno unless they explicitly asked to modify the spending limit.

Only when the human/operator explicitly asks to change the spending limit:

json

{ "name": "config_set", "arguments": { "maxSendXno": "5.0" } }

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Payment Requests

For tracked inbound funding workflows:

Step 1 — Check existing wallets and balance first

If sufficient funds already exist, skip creating a request.

Step 2 — Create request

json

{
  "name": "payment_create",
  "arguments": { "walletName": "my-wallet", "amountXno": "0.1", "reason": "testing payment flow" }
}

Returns: nano: URI, target address, and request ID.

Step 3 — Present to operator

Tell the user the amount, reason, and address. Offer a QR code (see QR Generation section).

Step 4 — Wait and receive

After the user says funds are sent:

json

{ "name": "payment_receive", "arguments": { "id": "<request-id>" } }

Returns status: pending, partial, funded, or received. If partial, tell the user how much more is needed.

Step 5 — Confirm

Report the received amount, updated balance, and that funds are ready.

Rules:

• Always check existing wallets first; don't create unnecessary wallets.
• Never claim receipt without calling payment_receive — pending is not received in Nano.
• If the operator asks "did you get it?", always re-check.

History:

json

{ "name": "wallet_history", "arguments": { "wallet": "my-wallet", "limit": 20 } }

Full options: payment_create, payment_receive, wallet_history

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Returning Funds

Core safety rule: never guess the refund destination. Always confirm with the operator.

Step 1 — Identify what to return

If linked to a payment request:

json

{ "name": "payment_refund", "arguments": { "id": "<request-id>", "execute": false } }

Otherwise, check history:

json

{ "name": "wallet_history", "arguments": { "wallet": "my-wallet", "limit": 20 } }

Step 2 — Evaluate and confirm

• Single source: Present the address and amount. Ask: "I received X XNO from nano_.... Shall I return it?"
• Multiple sources: List all candidates with amounts, ask which to refund.
• No sources: Report "No incoming transactions found to refund."

Always show the full address — never abbreviate.

Step 3 — Execute

json

{
  "name": "payment_refund",
  "arguments": { "id": "<request-id>", "execute": true, "confirmAddress": "nano_..." }
}

Or use wallet_send directly if not linked to a payment request.

Edge cases:

• "Return everything": list all accounts with balances, confirm before draining.
• "Return to [specific address]": validate the address first, then confirm amount.
• Spending limit blocks refund: report the current limit and ask whether the human/operator wants to change it. Never raise maxSendXno unless they explicitly request that configuration change.

Full options: payment_refund

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QR Generation

Generates a terminal-friendly ASCII QR code for a Nano address, optionally with an amount.

Via MCP:

json

{ "name": "util_qr", "arguments": { "address": "nano_...", "amountXno": "1.5" } }

Via CLI (required args only):

bash

bunx -y xno-skills@4.4.0 qr nano_1abc...

Full options: qr

CRITICAL — stdout truncation: Agents often have stdout truncated (e.g. <truncated 14 lines>). To display a full QR code:

1. Use --json and parse the "qr" field, or
2. Redirect to a temp file (> /tmp/qr.txt) and read it with a file-reading tool.

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Address Validation

All validation is offline — no network required.

Valid address format:

• Prefix: nano_ (65 chars total) or xrb_ (64 chars, legacy — still valid)
• Alphabet: 13456789abcdefghijkmnopqrstuwxyz (no 0, l, v, or i)
• Last 8 chars: Blake2b-40 checksum of the public key

Via MCP:

json

{ "name": "util_validate", "arguments": { "address": "nano_..." } }

Via CLI:

bash

bunx -y xno-skills@4.4.0 validate nano_1abc...

Full options: validate

Always validate before sending XNO to an untrusted address.

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Unit Conversion

XNO uses 30 decimal places. Floating-point arithmetic is unsafe. Always use this tool.

Unit	Raw value	Relation
raw	1	base unit
mnano	10²⁴	0.000001 XNO
knano	10²⁷	0.001 XNO
XNO	10³⁰	1 XNO

Via MCP:

json

{ "name": "util_convert", "arguments": { "amount": "1.5", "from": "xno", "to": "raw" } }

Via CLI:

bash

bunx -y xno-skills@4.4.0 convert 1 xno       # all units
bunx -y xno-skills@4.4.0 convert 1 knano
bunx -y xno-skills@4.4.0 convert 1000000000000000000000000000000 raw
bunx -y xno-skills@4.4.0 convert 1 xno --json

Full options: convert

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Message Signing & Verification (NOMS / ORIS-001)

OWS-backed signing via MCP — Not yet available

The sign_message and verify_message MCP tools require OWS upstream support that has not yet merged. If the user asks you to sign or verify a message using their wallet:

Sorry, OWS-backed NOMS message signing is not available yet in xno-mcp. It depends on an upstream pull request. If you'd like this feature, please add a 👍 at: https://github.com/open-wallet-standard/core/pull/217

Low-level CLI signing (raw private key)

Signing with a raw hex private key works via CLI today, but the agent must never handle the key value. A raw private key passed through an LLM context is exposed to logs, memory, and any downstream system — treat it like a password.

Agent's role: construct the command with a placeholder and ask the user to run it themselves in their own terminal.

Present the user with this command to run locally:

bash

# Sign — run this yourself, replacing the placeholder with your actual key
bunx -y xno-skills@4.4.0 sign "<message>" --key YOUR_PRIVATE_KEY_HEX

# Sign with JSON output
bunx -y xno-skills@4.4.0 sign "<message>" --key YOUR_PRIVATE_KEY_HEX --json

For verify, the agent can run this directly (no secret material involved):

bash

# Verify
bunx -y xno-skills@4.4.0 verify <nano_address> "<message>" <signature-hex>

# Verify with JSON output
bunx -y xno-skills@4.4.0 verify <nano_address> "<message>" <signature-hex> --json

NOMS standard (ORIS-001): Signatures are computed over a binary payload with a magic header, ensuring a valid signature cannot be misinterpreted as a Nano transaction block.

Note: verify accepts both nano_/xrb_ addresses and raw 32-byte hex public keys.

Do not prompt the user to export their mnemonic to get a private key. Never accept, repeat, or emit a private key value — only use the placeholder pattern above.

Full options: sign, verify

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Block-Lattice Mental Model

The ledger is a block lattice — a set of completely independent account-chains.

• Every account maintains its own linear chain of state blocks.
• Only the account owner (private-key holder) can append to their chain.
• No global mempool, no miners, no gas fees, no block producers.
• Each block records the full current state of its account (balance, representative, previous hash).
• Total supply is fixed at genesis.

Universal State Blocks

All blocks today are Universal State Blocks (type: "state"):

json

{
  "type": "state",
  "account": "nano_...",
  "previous": "64-hex...",       // frontier hash, or "0" for open block
  "representative": "nano_...",
  "balance": "decimal-string",   // new balance in raw (1 XNO = 10^30 raw)
  "link": "...",                 // send: destination address; receive: send block hash; change: "0"
  "signature": "128-hex...",
  "work": "16-hex..."
}

The Account-Chain Dance

Alice sends to Bob:

1. Alice builds a Send block: previous = her frontier, balance = old − amount, link = Bob's address.
2. Alice signs + PoW + broadcasts. Funds are irrevocably deducted from Alice and become pending on Bob's chain.

Bob must claim:

1. Bob builds a Receive block: previous = his frontier (zeros for open), balance = old + amount, link = Alice's send block hash.
2. Bob signs + PoW + broadcasts. Only then are funds spendable.

Critical: The send is final for Alice. Funds are not spendable by Bob until his receive block is confirmed. There is no automatic receive. Pending funds sit forever until claimed.

PoW Thresholds (Epoch v2, 2026)

• Send / Change: fffffff800000000
• Receive / Open: fffffe0000000000

PoW input:

• Open block (height 1): blake2b(nonce || public_key)
• All other blocks: blake2b(nonce || previous_frontier_hash)

Representatives & ORV

• Voting weight = balance delegated to a representative.
• Quorum = >67% of online weight → confirmed → cemented (deterministic finality, typically <1s).
• Choose representatives with high uptime, low voting weight concentration, and trustworthy operators.
• Lists: blocklattice.io/representatives, nanoticker.org

Change representative:

json

{ "name": "wallet_change_rep", "arguments": { "wallet": "my-wallet", "representative": "nano_..." } }

bash

bunx -y xno-skills@4.4.0 change-rep --wallet "my-wallet" --representative "nano_..."

Full options: change-rep

Data Representations

• Seed: 32 bytes (64 hex, uppercase)
• Private key: blake2b(32, seed || index), index as 4-byte big-endian uint
• Address: nano_ + 52-base32(public key) + 8-base32(Blake2b-40 checksum). Total 65 chars.
• Block hash / frontier: 32 bytes (64 hex)
• Signature: 64 bytes (128 hex), Ed25519 + Blake2b
• Work: 8 bytes (16 hex)
• Balance: always raw units as decimal string in JSON. Never floating-point.

Blockchain Explorer

• Always prefer blocklattice.io unless the user explicitly requests another explorer.
• Account: https://blocklattice.io/account/<nano_address>
• Block: https://blocklattice.io/block/<UPPERCASE_HEX_HASH>

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Configuration & Defaults

xno-mcp reads configuration from a JSON file on disk. It reloads the file before every operation, so manual edits take effect immediately. No restart required.

No configuration is required to get started. Defaults work out of the box:

• Public RPC nodes (rainstorm.city, nanoslo.0x.no/proxy, rpc.nano.to)
• PoW: local WASM/GPU by default; falls back to remote via the first RPC node when local is not performant
• Representative: nano_3arg3asgtigae3xckabaaewkx3bzsh7nwz7jkmjos79ihyaxwphhm6qgjps4
• Max per send: 1.0 XNO

Override precedence

Remote PoW URL (resolved in order):

1. NANO_WORK_URL env var
2. saved config workUrl
3. NANO_RPC_URL env var
4. saved config rpcUrl
5. default primary RPC node

RPC endpoint list (normal traffic):

1. explicit tool argument rpcUrl
2. saved config rpcUrl
3. NANO_RPC_URL env var
4. default RPC node list

Setting values

json

{ "name": "config_set", "arguments": { "workUrl": "https://my-node.example/api" } }

Resetting values

Setting a string field to "" or null clears the saved override (falls back to defaults):

json

{ "name": "config_set", "arguments": { "workUrl": "" } }

Setting a number field to null clears the saved override:

json

{ "name": "config_set", "arguments": { "powTimeoutMs": null } }

Omitted fields are preserved unchanged.

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RPC Error Recovery

"RPC request failed: All endpoints exhausted" is almost always transient (rate limiting, brief node restart). Follow in order, stopping as soon as one works:

Step	Action
1	Wait 5 s. Retry with identical arguments.
2	config_set({ rpcUrl: "https://rainstorm.city/api" }), retry.
3	config_set({ rpcUrl: "https://nanoslo.0x.no/proxy" }), retry.
4	config_set({ rpcUrl: "https://rpc.nano.to" }), retry.
5	Try any other public node, retry.
6	config_set({ rpcUrl: "" }) to reset. Stop — report to user.

Calling config_set with a new rpcUrl creates a fresh NanoClient, bypassing the exponential backoff cooldown on default endpoints.

Prohibited at every step: custom scripts, curl, CLI block commands, manual PoW.

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CLI Reference

All subcommands support --json for machine-readable output and --help for full options.

Subcommand	Description	Reference
wallets	List wallets with Nano accounts	wallets
balance	Show balance and pending amount	balance
receive	Receive pending blocks	receive
send	Send Nano	send
change-rep	Change representative	change-rep
submit-block	Sign and submit prepared block hex	submit-block
history	Show transaction history	history
info	Discover account state and representative	info
convert	Convert between XNO units	convert
qr	Generate QR code for address	qr
validate	Validate address or block hash	validate
sign	Sign NOMS message with private key	sign
verify	Verify NOMS message signature	verify
rpc account-balance	Fetch account balance via RPC	rpc_account-balance
rpc receivable	List receivable blocks via RPC	rpc_receivable
rpc account-info	Fetch account info via RPC	rpc_account-info
rpc probe-caps	Probe RPC node capabilities	rpc_probe-caps
block send	Build unsigned send block hex	block_send
block receive	Build unsigned receive block hex	block_receive
block change	Build unsigned change block hex	block_change
mcp	Start MCP server or view config	mcp

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Troubleshooting

If tools are behaving unexpectedly, call system_diag first to verify versions and environment:

json

{ "name": "system_diag", "arguments": {} }

Returns:

• xnoSkills.version — xno-skills version
• xnoSkills.path — resolved executable path
• xnoSkills.invocation — how it was launched (npm-global, npx, bunx, source, etc.)
• ows.version — @open-wallet-standard/core version
• ows.path — OWS package location
• environment.mockOws — whether mock mode is active
• environment.nanoRpcUrl — override RPC URL if set

CLI equivalent:

bash

xno-skills diag
xno-skills diag --json

diag does not make network calls. If Local PoW Recommended is false or PoW timing looks surprising, run xno-skills rpc probe-caps <effective-work-url> to verify remote work_generate support.

MCP Server Crashes & "Not connected" Errors

• OWS is an in-process library, NOT a daemon: There is no background "OWS daemon" or wallet service running. @open-wallet-standard/core is a library loaded entirely in-process by the MCP server and CLI.
• "Not connected" from MCP client: If an MCP client/agent receives a "Not connected" error on wallet_balance or any other tool, it typically means the underlying xno-mcp server process has crashed (usually due to a Rust native addon panic during PoW or backend initialization) or was terminated. It does not mean a background daemon is down.

PoW failures (POW_FAILED / timeout)

PoW is done locally by default. xno-skills uses WASM-based Proof of Work that runs in-process — no external work peer is required.

On first use, the system probes local backends to build a local-first execution plan. This probe itself runs real PoW and may take 5–15 seconds — this is normal and happens on the first PoW operation in a process.

Diagnose in order, stopping at the first resolution:

Step	Check	Action
1	Was this the very first send/receive on a fresh MCP or CLI process?	Allow for first-use warmup. Retry the operation once.
2	Did the error say "Timed out after 10000ms"?	That is the local WASM per-backend timeout. It means WASM itself failed or is unavailable. Check Node.js version (node --version) — WASM PoW requires Node 16+.
3	Is the system under heavy CPU load?	WASM PoW is CPU-bound. A send block requires ~8× more work than receive. Wait for load to drop, then retry.

---

Quick-Start Example

text

1. wallet_list: {}                    → discover "my-wallet" exists
2. wallet_balance: { wallet: "my-wallet" }    → check balance / pending
3. wallet_receive: { wallet: "my-wallet" }    → pocket any pending funds
4. wallet_send: { wallet: "my-wallet", destination: "nano_...", amountXno: "0.01" }