FC
Start free

Build and test decision graphs visually.

Flow designer

The flow designer is a visual graph editor for composing decision logic. Open it from Flows → select a flow.

Canvas basics

Action How
Pan Drag background
Zoom Scroll wheel or controls
Add node Drag from palette onto canvas
Connect Drag from node handle to another node
Select Click node or edge
Configure Inspector panel on the side
Delete Select + Delete key

Node position is saved in the graph JSON — reopening the designer preserves layout.

Palette

Node Purpose
Start Entry point; input schema + response type
HTTP Call an API source operation
Condition If/else branch (JSONata)
Transform Compute and store a value
Wait for event Pause until resume
Decision Set response fields
End Finish and return

→ Field-level detail: Node types

Inspector panel

Selecting a node opens the inspector:

  • Label / description — documentation for humans and agents
  • Type-specific fields — operation id, expressions, timeouts
  • Expression editor — Monaco with JSONata syntax and intellisense

Expressions see input and nodes.{id} from prior steps.

→ JSONata expressions

Wiring conditions

A condition node needs two outgoing edges:

condition_1 ──when: "true"──► path_a
            └──when: "false"──► path_b

Other node types use a single default edge (omit when).

HTTP nodes

  1. Ensure an API source exists
  2. Add HTTP node → pick source + operation
  3. Map inputs: parameter name → JSONata expression

Example mapping:

Parameter Expression
userId input.userId
status "active"

Response available as nodes.{nodeId}.body in downstream expressions.

Decision + end pattern

Modern flows use a response type on the start node:

start → … → decision (sets responseValues) → end

Each decision merges keys into the accumulator. The end node validates and returns.

Legacy flows without a response type may use decision.result as the final payload — migrate to response types for clearer contracts.

Input schema (start node)

Declare what callers send to /v1/evaluate:

Field Type Required
userId string yes
amount number yes

Drives runtime validation and expression intellisense.

Save, publish, sync

Action Effect
Save draft Updates server draft; visible to CLI on next pull
Publish (console) Creates callable version for evaluate API
fcc pull Copies draft JSON to .fetchcatch/flows/
fcc apply Pushes local JSON to server draft
fcc publish Snapshots draft as callable version (CLI path)

Editing the same flow in console and git without syncing causes conflicts — pull before apply.

Validation

The designer validates before save:

  • Missing start node
  • Duplicate node ids
  • HTTP node without operation
  • Condition without expression or branches
  • Unreachable nodes

Fix errors listed in the validation panel before publishing.

Testing

  1. Dry run via evaluate with "dryRun": true where supported
  2. Runs tab — inspect a live execution step-by-step
  3. Fixture input — use the evaluate panel in console (if available) or curl

→ Runs & debugging