Rewrite tone

Paste any message (email, Slack, commit message), pick a tone, get it

README Try it Source

Showcase — Rewrite tone

Paste any message (email, Slack, commit message), pick a tone, get it rewritten with the same facts and a different voice. Still one API call.

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

The frontend encodes <tone>\n---\n<message> into the single-string input the backend expects, which is how the def run(input: str) -> str contract stays the same across all three showcases in this week.

Stop

docker compose down

Run locally

Download the project as a ZIP and run it with Docker. Brings up a FastAPI backend + Next.js frontend on localhost:3000.

Download rewrite-tone.zip

unzip rewrite-tone.zip
cd rewrite-tone
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

Type some input, pick a provider, and run the same code shown in Source against the live API. Sign-in required.

Input

Provider

Output

The same modules the Run button hits. The whole project (frontend, Dockerfile, compose) is in the ZIP under README.

`backend/ai_openai.py`

"""Week 1 - Showcase 2 (OpenAI): rewrite a message in a chosen tone.

The frontend encodes the input as "<tone>\\n---\\n<message>" so the
def run(input: str) -> str contract stays the same as the other showcases.
"""
from openai import OpenAI

_client = OpenAI()


def run(payload: str) -> str:
    tone, _, message = payload.partition("\n---\n")
    tone = (tone or "neutral").strip().lower()
    message = (message or payload).strip()
    prompt = (
        f"Rewrite the following message in a {tone} tone. Preserve every fact, "
        "name, date, and number. Do not add or remove information. Return only "
        "the rewritten message, no preamble."
        f"\n\n---\n{message}\n---"
    )
    # Cap the response so the model can't run away on us. 2048 tokens
    # is roughly 6k characters — comfortably more than any reasonable
    # rewrite of an 8k-char input.
    response = _client.responses.create(
        model="gpt-5.4-nano", input=prompt, max_output_tokens=2048,
    )
    return response.output_text

`backend/ai_gemini.py`

"""Week 1 - Showcase 2 (Gemini): rewrite a message in a chosen tone."""
import os

from google import genai
from google.genai import types

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


def run(payload: str) -> str:
    tone, _, message = payload.partition("\n---\n")
    tone = (tone or "neutral").strip().lower()
    message = (message or payload).strip()
    prompt = (
        f"Rewrite the following message in a {tone} tone. Preserve every fact, "
        "name, date, and number. Do not add or remove information. Return only "
        "the rewritten message, no preamble."
        f"\n\n---\n{message}\n---"
    )
    # Cap the response so the model can't run away on us. 2048 tokens
    # is roughly 6k characters — comfortably more than any reasonable
    # rewrite of an 8k-char input.
    response = _client.models.generate_content(
        model="gemini-3.1-flash-lite", contents=prompt,
        config=types.GenerateContentConfig(max_output_tokens=2048),
    )
    return response.text