WriteFix — Deterministic Text Improvement Workflow Starter (Next.js 16)

Next.js AI text editor starter with deterministic prompt structure, schema-validated JSON output, and configurable tone presets.

WriteFix is an editing workflow for improving clarity and tone while preserving original meaning and technical accuracy.

It is designed for developers and agencies who need predictable editing behaviour, not another chat box wrapped around an API.

The problem WriteFix solves

Most teams edit text like this:

• Someone pastes text into an AI tool

• Tone and structure vary between runs

• Technical accuracy can be degraded

• Output may invent, simplify, or distort meaning

• There is no enforcement of editing rules

This makes AI editing unreliable for professional workflows.

WriteFix replaces this with a governed editing workflow.

What’s included

• Full Next.js 16 + TypeScript project

• Editing dashboard UI

• Single API route: POST /api/generate

• Config-driven tone system

• Branding is fully configuration-driven and not embedded in core logic.

• Strict JSON schema output contract

• Deterministic prompt construction

• Structured validation layer

• Jest test suite covering core generation logic

• Complete documentation set, including:

• Quick start guide

• Full installation and deployment guide

• Architecture overview

• Configuration reference

• Clean project structure suitable for extension

TwelveVoltsCo products are designed to be self-sufficient, with clear architecture and comprehensive documentation that minimise support dependency and enable confident modification.

How WriteFix works

• Users paste source text and select a tone

• WriteFix generates a structured prompt using defined rules

• The model must return JSON matching a strict schema

• The response is validated before returning to the client

• Only schema-compliant output is accepted

Every output follows the same structure, tone, and safety constraints.

Why this is not “just ChatGPT”

Without WriteFix:

• Editing behaviour varies unpredictably

• Tone enforcement is inconsistent

• Output structure is not guaranteed

• Automation workflows are fragile

With WriteFix:

• Editing rules are enforced

• Tone behaviour is controlled

• Schema compliance is enforced

• Output is predictable and automation-safe

This makes it suitable for real editing workflows.

Tone system (config-driven and editable)

WriteFix includes four tone presets:

• Formal

• Plain English

• Technical

• Friendly

New tones can be added or modified without changing API logic.

Behaviour governance

WriteFix is tuned to:

• Preserve technical accuracy

• Preserve meaning and intent

• Avoid inventing facts or claims

• Enforce deterministic output structure

• Reject invalid model responses safely

This prevents stylistic drift and unsafe output.

Tech stack

• Next.js 16 (App Router)

• TypeScript (strict)

• Tailwind CSS

• OpenAI API (provider configurable)

• Jest testing framework

What this is not

WriteFix does not include:

• Authentication or user accounts

• Multi-tenant SaaS infrastructure

• Persistent storage

• Billing integration

• Hosted deployment

This is a focused editing workflow baseline, not a finished SaaS.

Who this is for

• Developers building internal editing tools

• Agencies standardising editing workflows

• Teams requiring predictable editing behaviour

• Engineers integrating AI editing into automation pipelines

Who should not buy this

• Anyone looking for a hosted SaaS product

• Anyone looking for a general writing assistant

• Anyone expecting autonomous content generation

• Non-technical users without development experience

Licence tiers

All tiers include the full source code and documentation. Choose Solo, Agency, or Resale depending on how you plan to use and redistribute the starter.