Switch AI from OpenAI to Gemini 2.0 Flash (free, key exists)

All AI features now use Gemini 2.0 Flash via the existing API key.
Falls back to OpenAI if OPENAI_API_KEY is set instead.
Falls back to heuristics if neither key exists.

Gemini free tier: 15 RPM, 1M tokens/day, 1500 RPD
At PNPL's scale this is effectively unlimited and costs £0.

Changed:
- src/lib/ai.ts: chat() → tries Gemini first, OpenAI fallback
- src/app/api/automations/ai/route.ts: same dual-provider pattern
- docker-compose.yml: GEMINI_API_KEY added to app environment

All 11 AI features now work:
- Smart amount suggestions, message generation, fuzzy matching
- Column mapping, event parsing, impact stories, daily digest
- Nudge composer, donor classification, anomaly detection
- A/B variant generation, rewrites, auto-winner evaluation

pledge-now-pay-later/src/app/api/automations/ai/route.ts

@@ -2,16 +2,43 @@ import { NextRequest, NextResponse } from "next/server"
 import prisma from "@/lib/prisma"
 import { getUser } from "@/lib/session"
 
+const GEMINI_KEY = process.env.GEMINI_API_KEY
 const OPENAI_KEY = process.env.OPENAI_API_KEY
-const MODEL = "gpt-4o-mini"
+const HAS_AI = !!(GEMINI_KEY || OPENAI_KEY)
 
 async function chat(messages: Array<{ role: string; content: string }>, maxTokens = 600): Promise<string> {
-  if (!OPENAI_KEY) return ""
+  if (!HAS_AI) return ""
+
+  // Prefer Gemini (free), fall back to OpenAI
+  if (GEMINI_KEY) {
+    try {
+      const systemMsg = messages.find(m => m.role === "system")?.content || ""
+      const contents = messages.filter(m => m.role !== "system").map(m => ({
+        role: m.role === "assistant" ? "model" : "user",
+        parts: [{ text: m.content }],
+      }))
+      const res = await fetch(
+        `https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent?key=${GEMINI_KEY}`,
+        {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({
+            systemInstruction: systemMsg ? { parts: [{ text: systemMsg }] } : undefined,
+            contents,
+            generationConfig: { maxOutputTokens: maxTokens, temperature: 0.8 },
+          }),
+        }
+      )
+      const data = await res.json()
+      return data.candidates?.[0]?.content?.parts?.[0]?.text || ""
+    } catch { return "" }
+  }
+
   try {
     const res = await fetch("https://api.openai.com/v1/chat/completions", {
       method: "POST",
       headers: { "Content-Type": "application/json", Authorization: `Bearer ${OPENAI_KEY}` },
-      body: JSON.stringify({ model: MODEL, messages, max_tokens: maxTokens, temperature: 0.8 }),
+      body: JSON.stringify({ model: "gpt-4o-mini", messages, max_tokens: maxTokens, temperature: 0.8 }),
     })
     const data = await res.json()
     return data.choices?.[0]?.message?.content || ""
@@ -288,7 +315,7 @@ Rewrite it following the instruction.`
 
       // Generate new challenger
       let newChallenger = false
-      if (OPENAI_KEY) {
+      if (HAS_AI) {
         try {
           // Recursively call generate_variant
           const genRes = await fetch(new URL("/api/automations/ai", request.url), {

pledge-now-pay-later/src/lib/ai.ts

@@ -1,10 +1,12 @@
 /**
- * AI module — uses OpenAI GPT-4o-mini (nano model, ~$0.15/1M input tokens)
+ * AI module — uses Gemini 2.0 Flash (free tier: 15 RPM, 1M tokens/day)
+ * Falls back to OpenAI GPT-4o-mini if OPENAI_API_KEY is set instead
  * Falls back to smart heuristics when no API key is set
  */
 
+const GEMINI_KEY = process.env.GEMINI_API_KEY
 const OPENAI_KEY = process.env.OPENAI_API_KEY
-const MODEL = "gpt-4o-mini"
+const HAS_AI = !!(GEMINI_KEY || OPENAI_KEY)
 
 interface ChatMessage {
   role: "system" | "user" | "assistant"
@@ -12,8 +14,48 @@ interface ChatMessage {
 }
 
 async function chat(messages: ChatMessage[], maxTokens = 300): Promise<string> {
-  if (!OPENAI_KEY) return ""
+  if (!HAS_AI) return ""
 
+  // Prefer Gemini (free), fall back to OpenAI
+  if (GEMINI_KEY) return chatGemini(messages, maxTokens)
+  return chatOpenAI(messages, maxTokens)
+}
+
+async function chatGemini(messages: ChatMessage[], maxTokens: number): Promise<string> {
+  try {
+    // Gemini uses a different format: system instruction + contents
+    const systemMsg = messages.find(m => m.role === "system")?.content || ""
+    const contents = messages
+      .filter(m => m.role !== "system")
+      .map(m => ({
+        role: m.role === "assistant" ? "model" : "user",
+        parts: [{ text: m.content }],
+      }))
+
+    const res = await fetch(
+      `https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent?key=${GEMINI_KEY}`,
+      {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({
+          systemInstruction: systemMsg ? { parts: [{ text: systemMsg }] } : undefined,
+          contents,
+          generationConfig: {
+            maxOutputTokens: maxTokens,
+            temperature: 0.7,
+          },
+        }),
+      }
+    )
+    const data = await res.json()
+    return data.candidates?.[0]?.content?.parts?.[0]?.text || ""
+  } catch (err) {
+    console.error("[AI/Gemini]", err)
+    return ""
+  }
+}
+
+async function chatOpenAI(messages: ChatMessage[], maxTokens: number): Promise<string> {
   try {
     const res = await fetch("https://api.openai.com/v1/chat/completions", {
       method: "POST",
@@ -21,11 +63,12 @@ async function chat(messages: ChatMessage[], maxTokens = 300): Promise<string> {
         "Content-Type": "application/json",
         Authorization: `Bearer ${OPENAI_KEY}`,
       },
-      body: JSON.stringify({ model: MODEL, messages, max_tokens: maxTokens, temperature: 0.7 }),
+      body: JSON.stringify({ model: "gpt-4o-mini", messages, max_tokens: maxTokens, temperature: 0.7 }),
     })
     const data = await res.json()
     return data.choices?.[0]?.message?.content || ""
-  } catch {
+  } catch (err) {
+    console.error("[AI/OpenAI]", err)
     return ""
   }
 }
@@ -66,7 +109,7 @@ export async function suggestAmounts(context: {
 
   // AI-generated nudge (or fallback)
   let nudge = ""
-  if (OPENAI_KEY && context.pledgeCount && context.pledgeCount > 5) {
+  if (HAS_AI && context.pledgeCount && context.pledgeCount > 5) {
     nudge = await chat([
       {
         role: "system",
@@ -116,7 +159,7 @@ export async function generateMessage(type: "thank_you" | "reminder_gentle" | "r
   let msg = templates[type] || templates.thank_you
 
   // Try AI-enhanced version for reminders
-  if (OPENAI_KEY && (type === "reminder_gentle" || type === "reminder_urgent")) {
+  if (HAS_AI && (type === "reminder_gentle" || type === "reminder_urgent")) {
     const aiMsg = await chat([
       {
         role: "system",
@@ -174,7 +217,7 @@ export async function smartMatch(bankDescription: string, candidates: Array<{ re
  * Generate event description from a simple prompt
  */
 export async function generateEventDescription(prompt: string): Promise<string> {
-  if (!OPENAI_KEY) return ""
+  if (!HAS_AI) return ""
 
   return chat([
     {
@@ -194,7 +237,7 @@ export async function classifyDonorMessage(
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
   _fromPhone: string
 ): Promise<{ action: string; confidence: number; extractedInfo?: string } | null> {
-  if (!OPENAI_KEY) return null
+  if (!HAS_AI) return null
 
   const result = await chat([
     {
@@ -235,7 +278,7 @@ export async function autoMapBankColumns(
   referenceCol?: string
   confidence: number
 } | null> {
-  if (!OPENAI_KEY) return null
+  if (!HAS_AI) return null
 
   const result = await chat([
     {
@@ -271,7 +314,7 @@ export async function parseEventFromPrompt(prompt: string): Promise<{
   zakatEligible?: boolean
   tableCount?: number
 } | null> {
-  if (!OPENAI_KEY) return null
+  if (!HAS_AI) return null
 
   const result = await chat([
     {
@@ -301,7 +344,7 @@ export async function generateImpactMessage(context: {
   impactUnit?: string  // e.g. "£10 = 1 meal"
   goalProgress?: number  // 0-100 percentage
 }): Promise<string> {
-  if (!OPENAI_KEY) {
+  if (!HAS_AI) {
     return `Your £${context.amount} pledge to ${context.eventName} makes a real difference. Ref: ${context.reference}`
   }
 
@@ -334,7 +377,7 @@ export async function generateDailyDigest(stats: {
 }): Promise<string> {
   const collectionRate = stats.totalPledged > 0 ? Math.round((stats.totalCollected / stats.totalPledged) * 100) : 0
 
-  if (!OPENAI_KEY) {
+  if (!HAS_AI) {
     // Smart fallback without AI
     let msg = `🤲 *Morning Update — ${stats.eventName || stats.orgName}*\n\n`
     if (stats.newPledges > 0) msg += `*Yesterday:* ${stats.newPledges} new pledges (£${(stats.newPledgeAmount / 100).toFixed(0)})\n`
@@ -379,7 +422,7 @@ export async function generateNudgeMessage(context: {
 }): Promise<string> {
   const name = context.donorName?.split(" ")[0] || "there"
 
-  if (!OPENAI_KEY) {
+  if (!HAS_AI) {
     if (context.clickedIPaid) {
       return `Hi ${name}, you mentioned you'd paid your £${context.amount} pledge to ${context.eventName} — we haven't been able to match it yet. Could you double-check the reference was ${context.reference}? Thank you!`
     }