n8n

The Vestiarion nodes connect a workspace to n8n, the workflow tool. They do three things:

• Add bills from your other tools. A form, an inbox, a spreadsheet row or an accounting tool becomes a bill for the agent to decide.
• Read what the agent decided. Bills, counterparties, the workspace's status, and the agent's decisions with its reasoning.
• Start a workflow on each decision. The Vestiarion Trigger receives the signed ledger entry the moment the agent writes it, and checks its signature before anything runs.

They are one package, @vestiarion/n8n-nodes-vestiarion on npm, and they call this API with a workspace API key. They work the same on Arc testnet and on Arc mainnet.

Watch it#

Under four and a half minutes, in one take with no sound: the nodes installed from npm, a credential tested, a bill added, the agent's decisions read, the node as an AI agent's tool, and the trigger's filters. The sections below go through each part in full.

The same video is on YouTube.

It was recorded on 0.1.2. Since 0.1.3, Bill > Create's Currency is under Additional Fields, the trigger's Domains, Actions and Include Test Deliveries are under Options, and the trigger shows no setup notice: Set it up has every step. A workflow saved with 0.1.2 needs those fields set again.

Install#

In a self-hosted n8n, a user with the owner or admin role installs it:

1. Open Settings, then Community nodes.
2. Choose Install, and enter @vestiarion/n8n-nodes-vestiarion.
3. Tick that you understand the risks of installing community nodes, and choose Install.

The nodes then appear in the nodes panel: search for Vestiarion. They are built and tested against n8n 2.45.

n8n installs community packages it has not verified only while N8N_UNVERIFIED_PACKAGES_ENABLED is true. That is the default today, and n8n has said it will change to false in a future version: set it to true in the instance's environment to keep installing this package.

n8n Cloud lists only community nodes n8n has verified. This package is not verified yet, so on n8n Cloud, use the HTTP Request node with the API for now.

The site serves the same package, byte for byte: vestiarion-n8n-nodes-vestiarion-0.1.3.tgz.

Credentials#

Create one Vestiarion API credential. It has three fields:

n8n tests the credential with one read, GET /api/v1/status, and says whether the key works. The key is sent as Authorization: Bearer, never in a URL. The signing secret is never sent anywhere: the trigger uses it to check signatures.

The Vestiarion node#

Each operation calls one API operation, and nothing the API does not have.

No operation approves, rejects or pays: no key can. The node can also be a tool of an n8n AI agent, with the same operations.

Create a bill#

• Counterparty: the vendor or contractor the bill is from. Pick it from the list, which searches the workspace's vendors and contractors by name, or give its ID.
• Amount: as text, such as 1250.50, so it stays exact. At most 6 decimal places.
• Due Date: the day the bill is due. A date from the picker, a date as text, or an expression such as {{ $now.plus({ days: 30 }) }}, read in the workflow's time zone.
• Additional Fields:
  • Currency: USDC, the default when it is not set, or EURC.
  • PO Reference and Goods Received. Without both, the agent asks for the missing detail instead of paying.
  • Memo, up to 280 characters.
  • Early-Payment Discount Percent and Deadline, both or neither.
  • Idempotency Key: your own record's ID, such as the invoice's ID in the tool it comes from. It is sent as the Idempotency-Key, so running the same item again within 24 hours adds the bill once: the API keeps a key for 24 hours. Up to 255 characters, with no spaces. Without it, a rerun, or n8n's Retry On Fail, adds another bill. A sync that can read the same invoice again days later needs its own record of what it has added, such as a column in the sheet it reads.

The node outputs the bill as the API added it, with its id and status.

Read the agent's decisions#

Decision: Get Many reads the entries the agent signed into the ledger, oldest first, with the reasoning each one records. Domain keeps one domain, such as Bills. With Simplify on, the default, each decision is its seq, ts, domain, action, summary, reasoning, invoiceId or milestoneId, and cursor; turn it off for the whole signed entry, hashes and signature included.

To read on a schedule, two options keep each run to what is new:

• After Seq leaves out every entry up to that seq. Store the highest seq a run handled, and pass it next time.
• After Cursor starts the read there rather than at the first entry, so a long ledger is not read again. Each entry carries cursor for this. A read from a cursor returns its last page again, as the ledger's API says, and a read that fits on one page has no cursor at all, null: After Seq still leaves out what you have seen.

For decisions as they happen, use the trigger.

Errors#

An API error stops the node with the API's own message, such as "This key cannot do that." for a read-only key adding a bill, and its status and code, such as HTTP 403 forbidden. A 429 adds when to retry. With the node's On Error setting at Continue, each failed item outputs { "error": "..." }, and the rest go on.

The Vestiarion Trigger#

The trigger starts a workflow on each webhook delivery the workspace sends: one for each entry signed into its ledger.

Set it up#

1. Add a Vestiarion Trigger to a workflow, with the credential, and copy its Production URL.
2. In Vestiarion, an owner or an admin opens Settings, then Webhooks, and adds an endpoint with that URL.
3. Settings shows the endpoint's signing secret once. Copy it into the credential's Webhook Signing Secret.
4. Publish the workflow in n8n, so the Production URL is live.

The API cannot add a webhook endpoint, so step 2 is done by hand, once. Removing the trigger from n8n leaves the endpoint in Settings: delete it there.

Settings takes only an HTTPS URL, on port 443, at a public address. So a self-hosted n8n needs a public HTTPS address in front of it, set as its N8N_WEBHOOK_URL as n8n's docs describe: its default http://localhost:5678 cannot receive deliveries. Where n8n cannot be reached from the internet, use a Schedule Trigger with Decision: Get Many and its cursor instead.

To try it before you publish, add the trigger's Test URL as the endpoint instead, and copy its signing secret into the credential. Choose Listen for test event in n8n, then Send test beside the endpoint in Settings, within two minutes. Settings cannot change an endpoint's URL, so afterwards remove that endpoint and add the Production URL as a new one. The new endpoint has a new signing secret: put it in the credential. Do not leave the Test URL's endpoint in place: every delivery fails while n8n is not listening, and an endpoint that fails 20 times in a row is disabled.

Choose what starts the workflow#

Events is the one field always shown. The others are under Options, each left out until you add it.

What it checks#

Before anything runs, the trigger checks the delivery's Vestiarion-Signature against its raw body with the signing secret, as Verifying signatures describes:

• A signature that does not match, is missing, or is more than 300 seconds from now is answered 401, and nothing runs. After repeated failures, Vestiarion disables the endpoint.
• A credential with no signing secret fails the run with "The credential has no Webhook Signing Secret". The trigger never takes an unsigned delivery.
• A signed delivery your options leave out is answered 200, so Vestiarion does not send it again, and nothing runs.

What it outputs#

One item, the delivery as it was signed. Shortened here, detail especially:

{
  "id": "3fa1e2b0-...",
  "type": "ledger.appended",
  "createdAt": "2026-11-03T08:00:00.370366+00:00",
  "workspace": { "slug": "your-workspace" },
  "entry": {
    "seq": 9042,
    "ts": "2026-11-03T08:00:00.370366+00:00",
    "actor": "agent",
    "domain": "ap",
    "action": "ap_hold",
    "summary": "HOLD invoice from Harbor Print Co. for 1250.5 USDC",
    "detail": { "invoiceId": "...", "decision": { "action": "hold", "reasoning": "..." } },
    "bodyHash": "...",
    "prevHash": "...",
    "hash": "...",
    "signature": "...",
    "signingKeyId": "9b03458d9a617871"
  }
}

The payload page describes every field. A delivery can arrive more than once, with the same id, as Delivery guarantees explains: if a repeat would matter, such as a message sent twice, skip an id you have handled.

Two workflows to start from#

Tell the team when the agent holds a bill. Vestiarion Trigger, with Events Agent Decisions and, under Options, Domains Bills and Actions ap_hold, ap_flag_fraud. Then a Slack or Telegram node, with a message such as {{ $json.entry.summary }}: {{ $json.entry.detail.decision.reasoning }}. Vestiarion's own Slack and Telegram notices already cover this, with a link to review the bill in Vestiarion; use n8n when the message goes somewhere else, such as a ticket.

Add bills from a spreadsheet. A Google Sheets Trigger on new rows, then Vestiarion: Bill: Create, with the counterparty's ID, the amount and the due date from the row, and Idempotency Key set to the row's invoice number. A row read twice adds one bill.

What it does not do#

• It never approves, rejects or pays a bill, and adds only bills.
• It does not add or remove the webhook endpoint in Vestiarion: Settings does.
• It sends no telemetry. The key goes only to the Base URL, and the signing secret goes nowhere.

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