ai-prompt-template Edge Function — Ai

ai-prompt-template — Fill prompt templates with dynamic variables

Replaces {{variableName}} placeholders in a prompt template string with supplied values, with optional strict mode to catch missing variables before sending to an LLM.

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API

POST /api/ai-prompt-template

Request body

Field	Type	Required	Default	Description
template	string	✅	—	Prompt string containing {{variableName}} placeholders
variables	object	✅	—	Key-value map of placeholder names to replacement values (string, number, boolean)
strict	boolean	❌	true	If true, throw when any placeholder is unresolved

Success response (200)

{
  "success": true,
  "data": {
    "prompt": "Hello, Alice! Your task is to summarize the document.",
    "resolvedCount": 2,
    "unresolvedPlaceholders": []
  }
}

Error responses

Code	HTTP	When
INVALID_INPUT	400	Missing required field or wrong type
INTERNAL_ERROR	500	Unresolved placeholder in strict mode

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Usage

cURL

curl -X POST "$FUNCTION_URL" \
  -H "Content-Type: application/json" \
  -d '{
    "template": "Hello, {{name}}! Your task is to {{task}}.",
    "variables": { "name": "Alice", "task": "summarize the document" }
  }'

TypeScript / JavaScript (HTTP)

const response = await fetch(FUNCTION_URL, {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    template: 'Translate the following to {{language}}:\n\n{{text}}',
    variables: { language: 'French', text: 'Good morning!' },
  }),
});
const { data } = await response.json();
console.log(data.prompt);

Direct import (Node / Bun / Deno)

import { aiPromptTemplate } from '@aerostack/functions/ai-prompt-template';

const result = aiPromptTemplate({
  template: 'You are a {{role}}. Answer the following: {{question}}',
  variables: { role: 'helpful assistant', question: 'What is RAG?' },
});
console.log(result.prompt);

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Use Cases

• Building a prompt library where each entry uses {{placeholders}} for user-supplied data before sending to an LLM API.
• Generating personalised email drafts or support replies by filling in customer name, product, and issue variables.
• Validating prompt templates during CI — set strict: true and check that all placeholders resolve before deploying.

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Notes

• Placeholder syntax is {{variableName}} — double curly braces, alphanumeric + underscores only.
• Values are coerced to strings; numbers and booleans are supported.
• When strict: false, unresolved placeholders are left as-is in the output and listed in unresolvedPlaceholders.
• Consecutive blank lines in the resolved prompt are collapsed to a maximum of two.