Dry-run render a Prompt template

POST /v1/prompt-templates/{prompt_template_id}/render

Property	Value
Operation	`render_prompt_template`
Group	Prompt templates
Scope	`prompts:read`
Route class	`read`
Idempotency	`Idempotency-Key` accepted: a retry with the same key replays the first answer
Audit	Not audited: A dry run: it changes no state and reads no Call content, so it writes no Audit event (ADR 0012, prompt-manager.md section 7).
Released in	1.55.0
Phase 0 host	Served (the hosted api pins 1.65.0)

Renders the draft, or a version, for one variant with the synthetic variables, slots, state, Call fields, constants and retrieval outcomes of the body, and answers its section with a token estimate, the stable prefix, the names of missing values and the lint findings (1.55.0). A body that does not parse is 422 validation_failed with template_invalid; a value of the wrong type is variable_type. It writes nothing: no Call, Audit or Usage event.

Request

Set VOCAL_API to the base URL of your API and VOCAL_API_KEY to an API key with the prompts:read scope (Authentication and keys). Replace each placeholder, such as agt_... or <name>, with your own value.

curl -X POST "$VOCAL_API/v1/prompt-templates/ptpl_.../render" \
  -H "Authorization: Bearer $VOCAL_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{}'

const response = await fetch(`${process.env.VOCAL_API}/v1/prompt-templates/ptpl_.../render`, {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${process.env.VOCAL_API_KEY}`,
    'Idempotency-Key': crypto.randomUUID(),
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({}),
});
console.log(response.status, await response.text());

import os
import uuid

import requests

response = requests.post(
    f"{os.environ['VOCAL_API']}/v1/prompt-templates/ptpl_.../render",
    headers={
        "Authorization": f"Bearer {os.environ['VOCAL_API_KEY']}",
        "Idempotency-Key": str(uuid.uuid4()),
    },
    json={},
)
print(response.status_code, response.text)

Parameters

Name	In	Type	Required	Description
`prompt_template_id`	path	PromptTemplateId	yes	The id of a Prompt template: `ptpl_` and the row's UUIDv7 in 26 Crockford base32 characters. Opaque and safe to log.
`idempotency-key`	header	string	no	A client-chosen key, kept 24 hours per Organization, environment and route. A replay returns the stored response.

Request body

Content type application/json, required: PromptTemplateRenderRequest.

Field	Type	Required	Description
`call`	PromptRenderCallInput	no
`constants`	map of PromptConstantValue	no	Organization constants for this render; those of the Organization layer the render resolves when omitted. `display_name` is the Organization name.
`retrieval`	map of boolean	no	Whether each Knowledge binding returned passages for this request, by handle: `true` renders the first branch of its retrieval slot, `false` or absent the second.
`slots`	map of PromptSlotValue	no	Synthetic slot values; an unset slot renders empty or its `default()`.
`state`	string	no	The active state, the `state` root.
`time_now`	RequestTimestamp	no	The `time.now` root; the request instant when omitted.
`variables`	map of VariableValue	no	Synthetic values of the declared variables. A value of an undeclared name is `variable_unknown`, of the wrong type `variable_type`; an optional variable without a value renders empty and is named in `missing_values`.
`variant`	PromptVariantKey	no	The variant to render; `default` when omitted, and `default` for a key the template lacks.
`version`	integer	no	The version to render; the draft when omitted.

Responses

Status	Content type	Shape	Error codes
`200`	`application/json`	PromptRenderResult
`400`	`application/json`	ErrorEnvelope	`invalid_request`
`401`	`application/json`	ErrorEnvelope	`unauthenticated`
`403`	`application/json`	ErrorEnvelope	`forbidden`
`404`	`application/json`	ErrorEnvelope	`not_found`
`409`	`application/json`	ErrorEnvelope	`idempotency_in_progress`, `idempotency_key_reused`
`422`	`application/json`	ErrorEnvelope	`validation_failed`
`429`	`application/json`	ErrorEnvelope	`rate_limited`
`500`	`application/json`	ErrorEnvelope	`internal_error`

Fields of the `200` answer

The shape is PromptRenderResult.

Field	Type	Required	Description
`lint`	array of PromptLintFinding	yes	The lint findings of what was rendered: the stored findings of a version, those of the draft, and for an Agent version the cross-checks of its publish.
`missing_values`	array of PromptValuePath	yes	The paths that rendered empty for want of a value, such as `variables.clinician_name` (`missing_value`); names only, never a value.
`object`	`"prompt_render"`	yes
`sections`	array of PromptRenderSection	yes	In composition order.
`stable_prefix_tokens`	integer	yes	The tokens before the first per-Call or per-Turn value, which a Provider that caches prompts may reuse between requests (prompt-manager.md section 4).
`total_tokens`	integer	yes
`variant`	PromptVariantKey	yes