What it does: Walks a saved flow against the trigger’s sample payload — or one pasted on the screen — and reports which condition rules matched and what value each of them actually saw, then, per step, the exact request, message, option, meta, term or user it would produce. Nothing is sent, written or created, and no run is recorded. How to access: Flow Forge > Flows > Test, or the “Test this flow” card in the flow editor. Notes:

• The preview calls the real step handlers; every side effect is held back at one gateway rather than being re-described in a second engine, so what it reports is what a live run does.
• A step is only previewed if the plugin that provides it has declared that its effects can be held back. Anything else is reported as not previewable and is never called.
• An approval step in a preview shows the request that would be sent, with a placeholder token — no row is written and no working link is printed.
• Credentials are masked, including where they sit inside a URL or a request body.
• HTTP and mail answers are stand-ins, not real replies: a green step means “the step ran”, not “the other end accepted it”.