> ## Documentation Index
> Fetch the complete documentation index at: https://docs.gnani.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Using Jinja for Dynamic System Prompts 

> Description of your new file.

### **Overview** 

The Jinja templating feature allows you to create powerful, dynamic System Prompts. By using variables that are resolved with real-time data before a call begins, you can build personalized and context-aware conversations. This guide explains how to use Jinja templates, the validation rules in place, and the benefits of this approach. 

## **Core Concept: Understanding Variable Types** 

Our system uses two distinct types of curly braces to handle variables from different sources. Understanding this distinction is crucial for building prompts correctly. 

### \*\*1. Server-Side Variables: \*\*

These variables are placeholders for data that you provide to the system *before* the call is initiated. 

* **Source:** The value for these variables must come from one of two places: 
* **Dynamic API Response:** Data fetched from your API endpoint just before the call. 
* **Pre-call Variables:** Data you provide when triggering the call via an API, especially during testing. 
* **Use Case:** Ideal for injecting customer-specific data like names, appointment details, order history, or account status. 
* **Example:** Hello  customer\_name , your appointment is scheduled for  booking\_date . 

### \*\*2. User-Input Variables:  \*\*

These variables are placeholders for information that is extracted directly from the **user's spoken message** during the conversation. 

* **Source:** The value is populated by the system based on the user's utterance. 
* **Use Case:** Perfect for capturing dynamic user choices or inputs within a conversation turn. 
* **Example:** If the prompt is “To confirm, you selected user\_selected\_option, right?”, the value of user\_selected\_option will be filled from what the user said in their previous turn. 

### ***Variable Reference Table***

| Syntax         | Example                | Source of Value                            | Required in API/Pre-call Variables? |
| :------------- | :--------------------- | :----------------------------------------- | :---------------------------------- |
| variable\_name | customer\_name         | Dynamic API response or Pre-call variable  | **Yes**                             |
| variable\_name | user\_selected\_option | Extracted directly from the User's Message | **No**                              |

### **Validation Rules and System Behavior** 

To ensure your prompts are reliable, the system validates the Jinja template syntax before you can save or test an agent. 

***Validation Checks:*** The System Prompt is validated for the following conditions: 

* **Correct Jinja Syntax:** Ensures all brackets and statements (e.g., `{{var}}`, `{ %if% }`) are correctly formatted. 
* **No Undeclared Variables:** All variables wrapped in double curly braces `{{...}}` must have a corresponding value provided either from the dynamic API or pre-call variables. 

### ***Error Handling***

The system's behavior changes based on the validation result: 

| Condition                                                           | Save / Test Buttons    | System Message                                   |
| :------------------------------------------------------------------ | :--------------------- | :----------------------------------------------- |
| **Valid Syntax**                                                    | ✅ Enabled              | –                                                |
| **Invalid Jinja Syntax**                                            | 🛑 Disabled            | "Invalid Jinja syntax."                          |
| **Variable Missing at Runtime** (Variable not in API/pre-call data) | ✅ Enabled (Save works) | "Call triggered failed." (Error during the call) |

### ***Agent Behavior***

* **Existing Agents:** Agents created before this feature will continue to function as normal until their System Prompt is modified and saved again. 
* **New & Updated Agents:** All new agents, or existing agents whose prompts are updated, must follow the Jinja formatting and validation rules. 

### **Examples** 

**1. Valid Syntax** 

```html theme={null}
Hello {{customer_name}}, your booking for a {{product_name}} is confirmed for {{booking_date}}. 
```

**2. Invalid Syntax** 

```html theme={null}
Hello {{customer_name}}. Your booking is on {{booking_date}.  
```

* **Error:** The curly braces for booking\_date are not closed. 
* **System Behavior:** The Save and Test buttons will be disabled until the syntax is corrected. 

**3. Advanced Example with Conditional Logic** 

```html theme={null}
Hello {{ customer_name }}.  
{% if loyalty_status == 'Gold' %} 
As a Gold member, you get a special 20% discount.  
{% elif loyalty_status == 'Silver' %} 
As a Silver member, you get a 10% discount. 
{% else %} 
Thank you for being our customer. 
{% endif %} 
Your order #{{ order_id }} is ready.  
```

*In this example, the agent's greeting is personalized based on the customer's loyalty\_status variable.* 

### **How Jinja Optimizes Cost and Performance** 

Using Jinja templates, especially with conditional blocks (`{% if %}`, `{% elif %}`, `{% else %}`), significantly optimizes your prompts. 

* **Reduces Input Tokens:** By including only the relevant text based on the provided variables, the overall length of the prompt sent to the language model is reduced. 
* **Lowers Inference Costs:** Fewer input tokens directly translate to lower API costs for each call. 
* **Improves Execution Speed:** Shorter, more concise prompts are processed faster by the language model, reducing latency. 

<Info>
  **Important Note:** During **testing mode**, if a variable exists in both the pre-call variables and the dynamic API response, the value from the **pre-call variables will be used**. 
</Info>