In Description Files

Using systemPromptTemplate in YAML and JSON agent description files — automatic conversion to PromptTemplate.

Agent description files and strategy files support templates via the systemPromptTemplate field:

name: reviewer
model: openai/gpt-4o
systemPromptTemplate:
  template: "You are {{ role }}, reviewing {{ language }} code."
  variables:
    role: senior engineer
    language: TypeScript

When both systemPromptTemplate and systemPrompt are present, the template takes precedence. The loader converts systemPromptTemplate to a PromptTemplate automatically, so the agent receives the same object as if you had passed createPromptTemplate(...) as systemPrompt.

Using templates with loadAgent

Any agent loaded via loadAgent or loadAgentFromString supports systemPromptTemplate:

# agents/reviewer.yaml
name: reviewer
model: openai/gpt-4o
systemPromptTemplate:
  template: "You are {{ role }}. Focus on {{ focus }}."
  variables:
    role: a reviewer
    focus: correctness
tools:
  - read_file
  - edit_file

import { loadAgent } from "@comma-agents/core";

const agent = await loadAgent("./agents/reviewer.yaml");

// Variables are baked in — the template renders automatically at call time.
const result = await agent.call("Review this code.");

// Override at runtime without modifying the YAML.
agent.updatePromptVariables({ focus: "performance" });

Strategy files

Strategy files support the same systemPromptTemplate field on LLMAgentDef:

strategy: "1.0"
agents:
  - name: coder
    model: openai/gpt-4o
    systemPromptTemplate:
      template: "You are a {{ role }} writing {{ language }}."
      variables:
        role: software engineer
        language: TypeScript

The strategy loader builds the agent with the same template logic — systemPromptTemplate takes precedence over systemPrompt.

Prompts & Templates — overview and createPromptTemplate.
Template Overrides — updating variables at runtime.
Template Syntax — LiquidJS syntax and custom filters.
loadAgent — loading agents from description files.

In Description Files

Using templates with loadAgent

Strategy files

Related

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