feat: cooking assistant can propose creating a recipe

Gives the general chat a createRecipe tool (Vercel AI SDK, stepCountIs(3))
scoped so it can only ever produce a draft — the tool's execute is a pure
echo, no DB write. The route surfaces the tool call as proposedRecipe
alongside the normal text answer; the chat UI renders it as a card with
explicit Create/Discard buttons. Create POSTs to the existing
/api/v1/recipes endpoint — the same code path and tier/recipe-count limit
the manual editor already goes through — so there's exactly one place
that actually creates a recipe row, and nothing happens without the user
clicking Create.

Scoped to the general assistant only (not per-recipe chat), and to one
tool for now — addToShoppingList/generateMealPlan are follow-ups.

v0.45.0

apps/web/app/api/v1/ai/cooking-chat/route.ts

@@ -1,6 +1,6 @@
 import { NextRequest, NextResponse } from "next/server";
 import { z } from "zod";
-import { generateText } from "ai";
+import { generateText, stepCountIs } from "ai";
 import { db, chatMessages, aiConversations, sql } from "@epicure/db";
 import { requireSessionOrApiKey } from "@/lib/api-auth";
 import { applyRateLimit } from "@/lib/rate-limit";
@@ -8,6 +8,7 @@ import { withAiQuota, resolveAiConfigOrError } from "@/lib/ai/ai-error";
 import { getModelConfigForUseCase } from "@/lib/ai/resolve-user-key";
 import { resolveModel } from "@/lib/ai/factory";
 import { getUserPrivateBio, buildUserBioContext } from "@/lib/ai/user-bio";
+import { createRecipeTool } from "@/lib/ai/tools/create-recipe-tool";
 
 const Schema = z.object({
   question: z.string().min(1).max(500),
@@ -43,13 +44,16 @@ export async function POST(req: NextRequest) {
   const result = await withAiQuota(session!.user.id, session!.user.tier as "free" | "pro" | "team", () =>
     generateText({
       model,
-      system: `You are Epicure, a helpful culinary assistant answering general cooking questions — not tied to any specific recipe (techniques, substitutions, timing, equipment, food safety, etc). If asked who you are or what model/AI you're built on, say you're Epicure — never name the underlying model or provider. If a question has nothing to do with cooking or food, politely redirect. Keep answers under 200 words. Respond in ${lang}.${bioContext}`,
+      system: `You are Epicure, a helpful culinary assistant answering general cooking questions — not tied to any specific recipe (techniques, substitutions, timing, equipment, food safety, etc). If asked who you are or what model/AI you're built on, say you're Epicure — never name the underlying model or provider. If a question has nothing to do with cooking or food, politely redirect. Keep answers under 200 words. Respond in ${lang}.\n\nYou can propose creating a recipe with the createRecipe tool when the user explicitly asks you to create, save, or write down a recipe — e.g. "make me a recipe for X" or "write that down as a recipe". Don't call it just because a recipe came up in conversation. When you do call it, still write a short text reply too (e.g. "Here's a draft — check it below and confirm if it looks right"), since calling the tool only drafts the recipe for the user to review; it never saves anything by itself.${bioContext}`,
       prompt: parsed.data.question,
+      tools: { createRecipe: createRecipeTool },
+      stopWhen: stepCountIs(3),
     }), { skipQuota: aiConfig.isByok }
   );
   if (!result.ok) return result.response;
 
   const { conversationId } = parsed.data;
+  const proposedRecipe = result.data.toolCalls.find((c) => c.toolName === "createRecipe")?.input;
 
   void db.insert(chatMessages).values([
     { id: crypto.randomUUID(), userId: session!.user.id, recipeId: null, conversationId, role: "user", content: parsed.data.question },
@@ -68,5 +72,5 @@ export async function POST(req: NextRequest) {
     `).catch((err) => console.error("[cooking-chat] failed to touch conversation", err));
   }
 
-  return NextResponse.json({ answer: result.data.text });
+  return NextResponse.json({ answer: result.data.text, proposedRecipe });
 }