Find your way round the canvas

When you open an agent, or start a new one with Launch Builder, the page keeps the heading Agents with the line Build modular AI workflows with reusable nodes underneath. The builder fills the rest of the page in four parts: the toolbar along the top, the Nodes panel on the left, the canvas in the middle, and the Details panel on the right. To get here in the first place, see Open Agent Builder.

app.centrus.ai/app/agents/workflow-builder

Agents

Build modular AI workflows with reusable nodes

Chase overdue invoices

1,240 / 10,000 creditsValidateResetDraft savedRunsSettingsSave and Publish

1

2

Weekday mornings

Daily at 09:15 · Mon, Tue, Wed, Thu, Fri

Fetch unpaid invoices

List invoices

Overdue by 1 to 14 days

Keep ALL of 3 rule(s)

Each overdue invoice

For each of incoming items

Draft chase email

GPT-5.6 Terra

Check before sending

Approve in panel (wait up to 1440 min)

Send chase email

1 action enabled

AI builderMap

Ready to publish5

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4

1. 1The toolbar, with the agent's name, your credits and the buttons that save, check and publish it.
2. 2The Nodes panel, where every step you can add is listed by group.
3. 3The canvas, where you arrange and connect steps.
4. 4The Details panel, which shows the settings of the step you have selected.
5. 5The validation pill, which tells you whether the agent is ready to publish.

The figures all show one agent, Chase overdue invoices. Every weekday at 09:15 it fetches unpaid invoices from BigChange, keeps the ones between 1 and 14 days overdue, and for each one drafts a polite chase email, waits for someone to approve it, then sends it from Outlook. Centrus works alongside BigChange here: the invoices stay in BigChange and the agent only reads them.

When you open a saved agent, the builder restores the view you last saved, so the canvas sits where you left it. If there is no saved view, it fits the agent on screen as far as the zoom allows. It also selects the first AI step (or the first step, if there is no AI step) so the Details panel has something to show straight away.

The toolbar changes as you work. Some buttons only appear once the agent has been saved, and some only appear when there is something for them to do. Here it is for a saved draft with unsaved changes, which is when the most buttons are showing.

Hover over the credits meter to see the detail behind it: credits used against the limit for the month, how many automations are active, how many runs are running or waiting against your concurrency limit, and the date the count resets. If your organisation's plan does not include Agent Builder, the meter reads Not entitled. The allowance and what each step costs are explained in Automation credits and usage limits.

• Runs and Settings only appear after the agent's first save, because a run needs a saved agent behind it. If you try to run a new agent, Centrus asks you to save it as a draft first. The Runs panel is covered in Read the Runs panel.
• Once an agent is published, the save button disappears and Update & Publish is the way to save further changes. Publishing and versions are covered in Publish, pause and restore versions.
• If the canvas has a Spike Test step, a Run spike test button appears, which runs only those steps. See Test an agent before it goes live.
• If someone has shared the agent with you at View level, the toolbar shows View only and there is no Reset, save or publish button. You can look round the canvas but not change it. See Share an agent.

The Nodes panel lists every step you can add, under the line Drag onto the canvas, or click to add. Steps are grouped by what they do, and each group heading shows how many steps it holds. Click a heading to open or close the group.

• Trigger steps decide how the agent starts, such as a schedule, an email arriving, a message in chat or an incoming call. An agent has exactly one. See Choose how an agent starts.
• Knowledge steps search your Centrus knowledge or the web, AI steps hold the instructions the model follows, and General and Integration steps work with files, data and your connected systems. All of them are described in Steps an agent can use.
• Control steps add conditions, loops, approvals and error handling. See Conditions, loops and approvals.
• Send SMS sits under General, and the Incoming voice call trigger, the Voice AI and Outbound call steps cover phone calls. See Send text messages and Make outbound calls and answer incoming calls.

1. 1Open the group that holds the step you want.
2. 2Drag the step onto the canvas and let go where you want it. It lands under the pointer.
3. 3Alternatively, click the step. Centrus adds it to the canvas and selects it, so its settings open in Details straight away.
4. 4Connect the new step to the rest of the agent, as described in the next section.

A clicked step is placed at a set spot on the canvas, a little further along for each step already there, rather than in the part you are looking at. If nothing seems to happen when you click, the step has probably landed out of view: click Fit view in the bottom left corner of the canvas to find it.

The button at the top right of the panel, Collapse nodes panel, folds it into a narrow strip to give the canvas more room. Click the strip's button, Expand nodes panel, to open it again.

Steps run in the order the connecting lines say, not the order they appear on screen. Each step has small round handles: inputs on the left edge and outputs on the right. AI steps also have a Tools handle on the top edge, for the knowledge and integration steps the AI can call on while it works.

1. 1Press and hold on an output handle on the right of a step.
2. 2Drag the line to an input handle on the left of the next step, and let go.
3. 3To connect without dragging, click one handle and then click the other.

The canvas will not let some connections snap into place. Only File Search, Web Search and integration steps can join an AI step's Tools handle, plus Send SMS on a Voice AI. Only an Incoming voice call trigger can lead into a Voice AI, and an Outbound call links to a single Voice AI. Everything else connects freely, and validation catches mistakes such as a flow that runs round in a circle. The one circle that is allowed is a loop body returning to its Loop step.

To remove a connection, click the line to select it and press Backspace or Delete. To move a connection to a different step, drag either end of the line onto another handle.

Most steps have one output, but control steps that make a decision have one handle for each outcome, stacked down the right edge in the colour of the step. Hover over a handle to see what it does. A Filter has one exit for items it keeps and one for items it discards, a Condition has one for true and one for false, a Loop has one that runs for each item and one that fires when every item is done, and an Approval has one for approved and one for rejected. Many steps can also have an extra exit for errors: set On error to Continue via error branch under Advanced: error & retry in Details.

Each overdue invoice

For each of incoming items

Draft chase email

GPT-5.6 Terra

Check before sending

Approve in panel (wait up to 1440 min)

Send chase email

1 action enabled

Loop bodyApprovedRejectedDone: fires once after every item, with the collected results

Connect each exit you need to the step that should follow it. An exit you leave unconnected simply ends that path. How each control step decides which exit to take is covered in Conditions, loops and approvals.

Click a step to select it and open its settings in Details. Click an empty part of the canvas to clear the selection. To select several steps, hold Shift and drag a box round them, or hold Cmd on a Mac (Ctrl on Windows) and click each one.

Each overdue invoice

For each of incoming items

Draft chase email

GPT-5.6 Terra

Check before sending

Approve in panel (wait up to 1440 min)

Send chase email

1 action enabled

Hold Shift and drag to select several steps

• Move steps by dragging them. With steps selected, the arrow keys nudge them, and Shift with an arrow key moves them further.
• Delete a selected step or connection with Backspace or Delete, or use the bin button in the step's Details header. Deleting a step also removes its connections.
• On a simple chain with no branches, the Details header shows Step 2 of 7 and up and down arrows that move the step earlier or later. The arrows are not shown once any step uses more than one exit.

There is no undo on the canvas, and deleting does not ask for confirmation. If you remove something by mistake on a saved agent, Discard changes in the toolbar brings back the last saved version, but it also throws away every other change since that save. Saving after each piece of work keeps that safety net close, and every save with changes is kept in Version history in Settings, so you can restore an older one. See Publish, pause and restore versions.

There is no copy and paste for steps. To reuse a whole agent, open Settings and choose Duplicate this agent.

Drag an empty part of the canvas to pan round it, or hold the space bar and drag. Scroll or pinch on a trackpad to zoom in and out, and double-click to zoom in on a spot. The controls in the bottom left corner do the same with a click. You can zoom out to half size and in to twice the normal size.

Weekday mornings

Daily at 09:15 · Mon, Tue, Wed, Thu, Fri

Fetch unpaid invoices

List invoices

Overdue by 1 to 14 days

Keep ALL of 3 rule(s)

Each overdue invoice

For each of incoming items

Draft chase email

GPT-5.6 Terra

Check before sending

Approve in panel (wait up to 1440 min)

Send chase email

1 action enabled

1

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3

5

AI builder

Hide map4

Ready to publish

1. 1Zoom in.
2. 2Zoom out.
3. 3Fit view, which brings every step into view. On a large agent it stops at the furthest zoom, so some steps may still be off screen.
4. 4Map shows a small map of the whole agent. It reads Hide map while the map is open.
5. 5The map. The unshaded box is the part of the canvas you are looking at. Drag on the map to move round, or scroll on it to zoom.

The AI builder button beside Map opens the assistant that builds and edits agents from a description. It has its own guide: Build your first agent from a message.

Panning and zooming never count as unsaved changes. The view is saved with the agent the next time you save it for another reason.

Details shows the settings of the selected step. With nothing selected it reads No node selected. The top of the panel is the same for every step; the fields below depend on the type of step, and each step's own guide explains them.

To make the panel wider or narrower, drag its left edge. It can be between 320 and 640 pixels wide, and the builder remembers your width in this browser. Clicking a step on the canvas opens the panel again if you have collapsed it.

Steps that use a connected system, such as Outlook or BigChange, have a Connection section. A new agent has to be saved as a draft before you can connect an account to it, because the connection belongs to the saved agent rather than to the step.

Later steps often need something an earlier step produced, such as the invoice reference from BigChange or the email the AI drafted. Step data references lists every step that runs before the selected one, in the order they sit on the canvas, with the fields each one is known to produce. It is closed until you open it, and it is not shown on trigger steps because nothing runs before them.

1. 1Select the step that needs the data, and open Step data references in Details.
2. 2Find the earlier step, and click the field you want. Its reference is copied to your clipboard.
3. 3Paste the reference into the field that needs it, such as an email subject or body.

A reference looks like {{ steps.instructions-global-1791540900000-5.json.structured }}. The long middle part is the step's internal ID, which never changes when you rename the step. In the To and Body fields of a Send SMS step, clicking a field inserts the reference into the box for you instead of copying it.

The fields listed are the ones Centrus knows each step usually produces. A connected system can return more. Run the agent once and open the run in the Runs panel to see the real field names, as the panel itself suggests.

Validation checks the whole agent for anything that would stop it running, such as a missing trigger, a step with a required setting left empty, or a flow that runs in a circle. The pill at the bottom of the canvas shows where things stand, and clicking it when it shows issues opens the Validation window.

• Not validated yet means nothing has been checked since you opened the agent.
• Validation outdated means you have changed the agent since the last check. Click Validate to check again.
• Ready to publish means the last check found nothing.
• Warnings will not stop you publishing, but are worth reading. Accounts that are not connected show here, for example.
• Errors stop the agent being published until you fix them.

Validation runs when you click Validate, when you save, and when you publish. Where an issue belongs to a particular step, the Validation window says Click to focus this node on the canvas, and clicking it takes you straight to that step.

Weekday mornings

Daily at 09:15 · Mon, Tue, Wed, Thu, Fri

Fetch unpaid invoices

List invoices

Overdue by 1 to 14 days

Keep ALL of 3 rule(s)

Schedule Trigger

Daily

1 error

Validation

A workflow must have exactly one trigger node.

Outlook is not connected. Open this node and connect the account.

Click to focus this node on the canvas

!Fix validation errors before publishing.

Every agent needs exactly one trigger. A second trigger, or none at all, is an error that blocks publishing, and because it belongs to the whole agent rather than one step there is no shortcut to it. Delete the extra trigger, or add one from the Trigger group if there is none.

When you publish, errors open the Validation window and stop the publish. Warnings open Publish with warnings? so you can decide whether to carry on. Nothing is saved while either window stops the publish; once it goes ahead, the agent is saved and then made live. To run an agent by hand at any time, use Run now in the Runs panel; it is not a trigger you add to the canvas.

The builder does not save as you go. Nothing you do on the canvas reaches Centrus until you save, and leaving the page, closing the tab or clicking the back arrow throws away unsaved changes without asking. Renaming the agent and editing its description count as changes, but panning and zooming do not.

• Save draft saves a new agent for the first time. Centrus confirms with Draft saved. You can now connect integrations and test run it., and Runs and Settings appear.
• Save changes saves a draft you have edited. When there is nothing new to save the button reads Draft saved and is greyed out.
• On a published agent, Update & Publish saves your changes and publishes them in one go.
• Every save also checks the agent, so the validation pill updates when you save.

Each save is kept as a version you can go back to. See Publish, pause and restore versions.

Discard changes asks you to confirm before it returns the canvas to the last saved version. Reset asks too, and then removes every step and connection. On a saved agent, Reset only changes the canvas in front of you, so Discard changes can still bring the saved version back until you save again. On an agent that has never been saved, there is nothing to go back to.

Click the full screen button at the right end of the toolbar to give the builder the whole browser window, without the Centrus menu or page heading. Everything else works as before.

app.centrus.ai/app/agents/workflow-builder

1

Chase overdue invoices

1,240 / 10,000 creditsValidateResetDraft savedRunsSettingsSave and Publish

2

Weekday mornings

Daily at 09:15 · Mon, Tue, Wed, Thu, Fri

Fetch unpaid invoices

List invoices

Overdue by 1 to 14 days

Keep ALL of 3 rule(s)

Each overdue invoice

For each of incoming items

Draft chase email

GPT-5.6 Terra

Check before sending

Approve in panel (wait up to 1440 min)

Send chase email

1 action enabled

AI builderMap

Ready to publish

1. 1In full screen, the back arrow becomes Exit full screen, so it returns you to the normal view rather than leaving the builder.
2. 2Exit full screen also returns you to the normal view.

The canvas responds to these keys and gestures:

• Backspace or Delete removes the selected steps and connections.
• Shift and drag draws a selection box. Cmd (Mac) or Ctrl (Windows) and click adds a step to the selection.
• The arrow keys nudge selected steps. Hold Shift to move them further.
• Hold the space bar and drag to pan.
• Scroll, pinch or double-click to zoom.

There are no shortcuts for saving, undo or copying, and Esc does not leave full screen.

The builder is designed for a computer screen. On a narrower screen it hides panels to make room for the canvas: below 1,024 pixels wide the Details panel is hidden, and below 768 pixels the Nodes panel goes too, so you cannot add steps or change their settings. Reset is hidden below 768 pixels and Validate below 640 pixels.

09:41

Centrus

Agents

Build modular AI workflows with reusable nodes

Chase overdue invoices

Save and Publish

Weekday mornings

Daily at 09:15 · Mon, Tue, Wed, Thu, Fri

Fetch unpaid invoices

List invoices

Overdue by 1 to 14 days

Keep ALL of 3 rule(s)

Each overdue invoice

For each of incoming items

Draft chase email

GPT-5.6 Terra

Check before sending

Approve in panel (wait up to 1440 min)

Send chase email

1 action enabled

Ready to publish

On a phone you can still open an agent, look over its steps, pan and zoom, open Runs to run it or check its history, and publish it. Most toolbar buttons show only their icons, the agent's name has little room, and even at the furthest zoom only a few steps fit on screen, so drag the canvas to see the rest. Do the building on a computer.