Role control

Ask one question, then switch the role behind it — plain teacher, skeptical

README Pruébalo Código

Showcase — Role control

Ask one question, then switch the role behind it — plain teacher, skeptical engineer, explain-to-a-nine-year-old, bulleted list. The question stays the same. Only the system prompt changes, and the answer changes with it.

Run

bash bootstrap-secrets.sh              # reads ../../../../.env, writes secrets/
docker compose up --build              # default: PROVIDER=openai

Open http://localhost:3000.

To run against Gemini instead:

PROVIDER=gemini docker compose up --build

What's where

backend/ai_openai.py — the ROLES map (the lesson) + the OpenAI call
backend/ai_gemini.py — same ROLES map, Gemini call
backend/main.py — identical FastAPI loader; reads PROVIDER and dispatches
frontend/app/page.tsx — textarea + role <select> + result
docker-compose.yml — two services, secrets mounted from ./secrets/

The frontend encodes <role>\n---\n<question> into the single-string input the backend expects, which keeps the def run(input: str) -> str contract identical across every showcase in this week.

Stop

docker compose down

Ejecútalo en tu máquina

Descarga el proyecto como ZIP y córrelo con Docker. Levanta un backend FastAPI y un frontend Next.js en localhost:3000.

Descargar role-control.zip

unzip role-control.zip
cd role-control
bash bootstrap-secrets.sh   # one-time: pulls API keys into ./secrets
docker compose up --build   # default provider: openai
# or:  PROVIDER=gemini docker compose up --build

Escribe algo, elige un proveedor y ejecuta el mismo código de Código contra la API real. Requiere iniciar sesión.

Entrada

Proveedor

Output

Los mismos módulos que ejecuta el botón Run. El proyecto completo (frontend, Dockerfile, compose) está en el ZIP, pestaña README.

`backend/ai_openai.py`

"""Week 2 - Showcase 1 (OpenAI): same question, different system prompt.

The whole lesson lives in ROLES. The user's text never changes; the
system instruction does, and the answer changes with it. The frontend
encodes the input as "<role>\\n---\\n<text>" so the
def run(input: str) -> str contract stays identical to every other showcase.
"""
from openai import OpenAI

_client = OpenAI()

# Each role is a system prompt. This is the only thing that varies between
# the answers — the user's question is passed through untouched.
ROLES = {
    "plain": "You are a patient teacher. Explain in plain language a beginner "
             "can follow. At most four sentences. No jargon without a gloss.",
    "skeptic": "You are a skeptical staff engineer in a design review. Push "
               "back. Name the risk or hidden cost first, then concede what "
               "actually holds up. Three sentences, blunt.",
    "five": "You are explaining to a curious nine-year-old. Use one everyday "
            "analogy. Two short sentences. No technical terms at all.",
    "bullets": "You answer only as a tight bulleted list. Three to five "
               "bullets, each under twelve words. No intro line, no summary.",
}


def run(payload: str) -> str:
    role, _, text = payload.partition("\n---\n")
    system = ROLES.get((role or "plain").strip(), ROLES["plain"])
    text = (text or payload).strip()
    response = _client.responses.create(
        model="gpt-5.4-nano",
        instructions=system,
        input=text,
        max_output_tokens=600,
    )
    return response.output_text

`backend/ai_gemini.py`

"""Week 2 - Showcase 1 (Gemini): same question, different system prompt."""
import os

from google import genai
from google.genai import types

_client = genai.Client(api_key=os.environ["GEMINI_API_KEY"])

# Identical role set to the OpenAI module, so swapping PROVIDER changes the
# SDK underneath without changing the lesson.
ROLES = {
    "plain": "You are a patient teacher. Explain in plain language a beginner "
             "can follow. At most four sentences. No jargon without a gloss.",
    "skeptic": "You are a skeptical staff engineer in a design review. Push "
               "back. Name the risk or hidden cost first, then concede what "
               "actually holds up. Three sentences, blunt.",
    "five": "You are explaining to a curious nine-year-old. Use one everyday "
            "analogy. Two short sentences. No technical terms at all.",
    "bullets": "You answer only as a tight bulleted list. Three to five "
               "bullets, each under twelve words. No intro line, no summary.",
}


def run(payload: str) -> str:
    role, _, text = payload.partition("\n---\n")
    system = ROLES.get((role or "plain").strip(), ROLES["plain"])
    text = (text or payload).strip()
    response = _client.models.generate_content(
        model="gemini-3.1-flash-lite",
        contents=text,
        config=types.GenerateContentConfig(
            system_instruction=system, max_output_tokens=600,
        ),
    )
    return response.text