API Routes & System Prompts

src/app/api/
  ├── [feature]+api.ts     ← Your app's core AI feature
  ├── vision+api.ts        ← Image analysis (boilerplate)
  ├── chat+api.ts          ← General AI chat (boilerplate)
  ├── generate+api.ts      ← Text/image generation (boilerplate)
  ├── transcribe+api.ts    ← Audio transcription (boilerplate)
  └── health+api.ts        ← Health check endpoint

const API_KEY = process.env.OPENAI_API_KEY; // or ANTHROPIC_API_KEY

interface FeatureRequest {
  inputText: string;
  mode?: string;
  options?: Record<string, unknown>;
}

const SYSTEM_PROMPT = `You are [EXPERT ROLE] specializing in [DOMAIN].

Your Role:
- [Primary responsibility]
- [Secondary responsibility]
- [Constraints and guidelines]

Output Rules:
- You MUST respond with ONLY valid JSON
- [Specific formatting rules]

You MUST respond with ONLY valid JSON in this exact format:
{
  "result": "string — the main output",
  "confidence": 0.0-1.0,
  "details": { ... },
  "disclaimer": "string — if applicable"
}`;

export async function POST(request: Request): Promise<Response> {
  try {
    const body: FeatureRequest = await request.json();
    const { inputText } = body;

    if (!inputText?.trim()) {
      return Response.json({ error: "Input text is required" }, { status: 400 });
    }

    if (!API_KEY) {
      return Response.json({ error: "API key not configured" }, { status: 500 });
    }

    const response = await fetch("https://api.openai.com/v1/chat/completions", {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        Authorization: `Bearer ${API_KEY}`,
      },
      body: JSON.stringify({
        model: "gpt-4o-mini",
        messages: [
          { role: "system", content: SYSTEM_PROMPT },
          { role: "user", content: inputText },
        ],
        response_format: { type: "json_object" },
        temperature: 0.7,
        max_tokens: 2000,
      }),
    });

    const data = await response.json();
    const result = JSON.parse(data.choices[0].message.content);
    return Response.json(result);
  } catch (error) {
    console.error("[API] Error:", error);
    return Response.json({ error: "Internal server error" }, { status: 500 });
  }
}

const response = await fetch("https://api.anthropic.com/v1/messages", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "x-api-key": process.env.ANTHROPIC_API_KEY!,
    "anthropic-version": "2023-06-01",
  },
  body: JSON.stringify({
    model: "claude-sonnet-4-20250514",
    max_tokens: 2000,
    system: SYSTEM_PROMPT,
    messages: [{ role: "user", content: inputText }],
  }),
});

const data = await response.json();
const result = JSON.parse(data.content[0].text);

const response = await fetch("https://api.openai.com/v1/chat/completions", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    Authorization: `Bearer ${API_KEY}`,
  },
  body: JSON.stringify({
    model: "gpt-4o",
    messages: [
      { role: "system", content: SYSTEM_PROMPT },
      {
        role: "user",
        content: [
          { type: "text", text: userPrompt },
          {
            type: "image_url",
            image_url: { url: `data:image/jpeg;base64,${base64Image}` },
          },
        ],
      },
    ],
    response_format: { type: "json_object" },
    max_tokens: 2000,
  }),
});

export function GET() {
  const hasOpenAI = !!process.env.OPENAI_API_KEY;
  const hasAnthropic = !!process.env.ANTHROPIC_API_KEY;

  return Response.json({
    status: "ok",
    timestamp: new Date().toISOString(),
    keys: {
      openai: hasOpenAI ? "configured" : "MISSING",
      anthropic: hasAnthropic ? "configured" : "MISSING",
    },
  });
}

# After deploying, verify:
curl https://your-app.expo.app/api/health

const MAX_INPUT_LENGTH = 5000; // characters

export async function POST(request: Request): Promise<Response> {
  const body = await request.json();
  let { inputText } = body;

  if (!inputText?.trim()) {
    return Response.json({ error: "Input text is required" }, { status: 400 });
  }

  // Truncate to prevent excessive API costs
  if (inputText.length > MAX_INPUT_LENGTH) {
    inputText = inputText.slice(0, MAX_INPUT_LENGTH);
  }

  // ... rest of API call
}

OPENAI_API_KEY=sk-...
ANTHROPIC_API_KEY=sk-ant-...

You are an expert linguistic transformer specializing in text rewriting and paraphrasing.

Your Role:
- Rewrite the given text in the specified mode while preserving the original meaning
- Maintain the same language as the input
- Never add commentary — return ONLY the rewritten text

Modes: FORMAL, CASUAL, ACADEMIC, CREATIVE, SIMPLIFY, EXPAND, SUMMARIZE

You MUST respond with ONLY valid JSON:
{"rewrittenText": "...", "mode": "...", "wordCount": 0}

You are Fishify's marine biologist AI. You identify fish species from photographs.

Identification Methodology:
1. Body shape analysis
2. Coloration and pattern
3. Fin configuration
4. Scale type and pattern

Confidence Guide:
- 90-100%: Distinctive species with clear features visible
- 70-89%: Strong match but some features obscured
- Below 50%: Insufficient detail

You MUST respond with ONLY valid JSON:
{
  "species": "Common Name",
  "scientificName": "Genus species",
  "confidence": 0.0-1.0,
  "description": "Brief description",
  "funFact": "Interesting fact"
}