Playground
Test drafts — including unsaved edits — with real payloads, read confidence and distributions, preview destinations, compare runs and replay inputs from past executions.
The Playground runs a decision's draft on a state you provide and shows everything the API would return, plus the full distributions. Use it to iterate on instructions and option descriptions before you deploy.
Open it from a decision's Playground tab, or from Playground in the sidebar and pick a decision there. On that page, a decision whose slug is a template id — such as lead-qualification — starts with the template's sample state.
What it runs
The Playground runs the draft, never the deployed version. From the decision's Playground tab it even runs edits you haven't saved yet, and it is blocked while the draft has schema issues; the sidebar's Playground page runs the last saved draft. When the decision is live, the header reminds you that production keeps the active version.
Run a state
- Write the state as JSON. For an object state, an object; for a text state, a JSON string such as
"Hi, I'd like pricing for 50 seats."; for a list state, an array such as["Hi!", "We're a team of 50 and want pricing."]. - Use Sample to generate a state from the state schema and Format to pretty-print it. The editor shows the size in bytes and whether the JSON is valid.
- Click Run decision or press ⌘/Ctrl + Enter.
Read the result
- The typed
result, the action badge and the reason in plain words — Policy rule #1 matched, "route" answered "other" (no option fits), "route" confidence 52% < 80%, Engine unavailable (ENGINE_TIMEOUT); fallback applied or No rule matched. - A confidence bar per question. Expand it to see the distribution over every option or level — and, for a score question, its weighted level (1 = first level), the number rules with weighted level compare. Questions with a near tie or below their minimum confidence open automatically.
- A Composites card with the value of each composite.
- Latency, model, estimated cost with the input tokens, and a link to the execution.
When the engine fails on a decision with onEngineError: "fallback", a warning says the decision answered with its fallback action and that the call isn't billed.
Destinations
For decisions with destinations, the result ends with a Destinations card. By default it is a preview and nothing leaves Dcision: fixed replies are rendered, LLM destinations show the prompt they would send, and webhooks, API requests, workflows and agents show the exact request — with secrets masked as ••••.
Switch on Run destinations for real, next to Run decision, to call the LLMs and agents and send the deliveries, marked livemode: false. The card then follows each delivery — sending, retrying, delivered or failed — and offers Resend on failures. See Testing destinations.
Compare runs
From the second run on, Compared with the previous run lists every answer and the action before and after, highlighting what changed — the fastest way to see the effect of a reworded instruction or option description.
Replay past inputs
In Executions, open a run and click Re-run this input in the Playground: the stored state loads into that decision's Playground, ready to run against the current draft. It's a quick regression test after an edit.
Replay needs the stored input, so it isn't available for executions of decisions with storeInput off.
Code snippets
Below the result, the Playground prints the same call as cURL, TypeScript and Python for the current state. They target the deployed endpoint, so they work once the decision is deployed and you have an API key.
Limits and cost
- Playground runs are not billed on any plan and don't use your monthly volume.
- They run on your workspace's engine settings: with your own provider key, the provider bills them.
- Up to 30 runs per minute and 2,000 runs per day per workspace; above that you get
429 RATE_LIMITED— use an API key for volume. - Every run is recorded in Executions with source Playground and version draft.
- Running the Playground needs the Member role or higher: Viewers can open it but not run it — see Team, roles and account.
Engines and BYOK
Decisions run on Jev or Laya. Use Dcision's key on TypeSafe, bring your own OpenRouter, TypeSafe or Vercel AI Gateway key, or run Laya on your own server — plus cost, limits and errors.
Executions and usage
Every run is logged with its version, action reason, confidence and — if you allow it — input and output. Find executions, read usage and know how long logs are kept.