A workflow diagram visualizes behavior: the ordered messages exchanged between objects during a process. It is generated from a workflow definition (a .wf artifact) and rendered as a sequence diagram — participants as lanes, messages as arrows over time.

In Studio you can also read the same workflow on the workflow objects diagram (wf-objects-diagram): the structural objects diagram with sequence steps mapped onto links. Playback animates each step on both surfaces at once.

Diagram source format

Workflow source text follows the Mermaid sequence diagram grammar: one construct per line, optional sequenceDiagram header, participant declarations, messages as <from><arrow><to>: <label>, and Mermaid-style fragments (alt, opt, loop, par, critical, box, rect) closed with end. Line comments use %%.

The example below is valid in both Mermaid and Studio:

sequenceDiagram
  participant Customer
  participant API
  Customer ->> API: Submit order
  API -->> Customer: Order accepted

Compatible with Mermaid

You can paste or author diagrams that follow the public Mermaid sequence syntax. Studio parses the same line-oriented body Mermaid documents for sequenceDiagram:

Message arrows

Every message line uses the same template:

<from><arrow><to>: <label>

<from> and <to> are participant ids. Spaces are optional (A ->> B : Hello equals A->>B:Hello). Self-messages (A->>A: retry) are allowed and render as a loop on that participant’s lane.

Studio accepts exactly these arrow literals (longest match wins, so C-->A is participant C, arrow -->, participant A — not a merged id):

In the visual editor, arrows containing -- (-->, -->>, <<-->>, --x, --)) render as dotted lines; the rest are solid.

Example mixing request, reply, and async:

  Client ->> API: Submit order
  API ->> Worker: Enqueue job
  Worker -) API: Accepted (async)
  API -->> Client: Order id

Any other arrow token (for example Mermaid half-arrows or central () connections) is not supported yet and produces a parse error.

Fragments

Fragments group messages inside labeled frames on the diagram (and in the steps view). Syntax matches Mermaid fragments: open with a keyword, optional title on the same line, put participant / message lines inside, close with end on its own line. Fragments can be nested — each end closes the innermost open frame.

Rules:

• else only immediately inside an open alt; otherwise the parser reports `else` without matching `alt`.
• and only inside par; otherwise `and` without matching `par`.
• option only inside critical; otherwise `option` without matching `critical`.
• A frame must contain at least one message (or a participant line) before end; empty alt … end is an error.
• Titles may be quoted: alt "HTTP 4xx".

Alternative (alt / else):

  alt Card approved
  Client ->> API: Capture payment
  else Card declined
  Client ->> API: Show error
  end

Optional (opt):

  opt Cache hit
  API -->> Client: Cached response
  end

Loop (loop):

  loop Every 5s
  Worker ->> API: Heartbeat
  API -->> Worker: OK
  end

Parallel (par / and):

  par
  API ->> Email: Send receipt
  and
  API ->> Analytics: Track event
  end

Critical (critical / option):

  critical Process payment
  API ->> Gateway: Charge
  option Gateway timeout
  API -->> Client: Payment pending
  end

Grouping (box) and highlight (rect):

  box Backend services
  participant API
  participant Worker
  API ->> Worker: Run job
  end

  rect rgb(240, 248, 255)
  Client ->> API: Login
  end

Studio-specific behavior

What it shows

• Participants (which are model objects).
• Ordered messages with arrows and replies.
• Optional grouping and an autogenerated steps list.
• The same steps overlaid on the objects diagram when you switch layout mode.
• Animated playback that walks through messages one step at a time.

sequenceDiagram
  Customer ->> API: Submit order
  API ->> Billing: Charge payment
  Billing -->> API: Payment confirmed
  API -->> Customer: Order accepted

Layout modes

The visual workflow editor toolbar offers three layouts:

Use Split when you want behavior and structure side by side. Use Objects when the architectural context matters more than the timeline.

Workflow objects diagram

The workflow objects diagram (wf-objects-diagram) is the same canvas as Explore / the Objects diagram: objects as nodes, YAML links as edges, automatic layout. The workflow is overlaid on top — each sequence message is mapped to a link between the participant objects.

How messages map to links

Virtual links are a signal to align structure with behavior: open the link sidebar and use Create model link to add the missing YAML relationship.

View vs editor on the objects pane

Linked selection

Selecting a message in the sequence diagram selects the corresponding link (or virtual link) on the workflow objects diagram, and vice versa. The link sidebar opens two tabs:

• Workflow steps — which sequence messages use this link
• Edit link — change the underlying YAML link (or create one from a virtual link)

Unresolved participants (no model object yet) appear as top-level gray nodes on the objects pane until you bind them to real objects.

Playback and animation

Click Play in the workflow toolbar to enter playback mode. A Play panel opens on the right with transport controls and a scrollable step list.

Controls

Each row in the step list shows the step number, participants, arrow type, and message text. Click a row to jump to that step.

What animates

During playback, the current step is emphasized on both diagrams:

• Sequence — the active message and its participants are highlighted; earlier steps stay visible in muted tones.
• Workflow objects diagram — the active step renders as a highlighted arrow (or on its mapped link). Previous steps remain in softer colors. With Show all steps, multiple played arrows are laid out to reduce overlap.

Branches, parallel, and async

For alt, the first branch is selected by default. Change the selection before or during playback to explore a different path.

Sequence diagram and steps list

Participants are model objects