AI Writing Apps: Prevent Prompt Fragility with Versioned Templates

Advanced Problem

AI-assisted writing apps break when prompt logic, fallback behavior, and editing UX are tangled together. The result is inconsistent output quality and difficult incident debugging.

Step 1: Treat prompt templates as versioned assets

{
  "template_id": "rewrite_v3",
  "system_role": "technical-writing-coach",
  "constraints": ["keep examples concrete", "avoid generic summaries"]
}

Step 2: Add provider fallback with quality gates

async function generateWithFallback(primary: () => Promise<string>, secondary: () => Promise<string>) {
  try {
    const out = await primary();
    if (out.length < 200) throw new Error('too_short');
    return out;
  } catch {
    return secondary();
  }
}

Step 3: Keep editing state independent from generation state

Writers should be able to revise manually without corrupting provider-level diagnostics.