feat: persist AI chat history, add search across it

Both chat panels (per-recipe and the general cooking assistant) previously
kept messages in component state only — closing the sheet or reloading
the page lost everything. Both POST routes now persist question+answer
pairs to a new chat_messages table (recipeId null for the general
assistant), and both panels load their own history back on open.

New GET /api/v1/ai/chat-history (scoped by recipeId, or scope=general for
the homepage assistant, or neither to search across everything) backs a
new search control in both panels' header — debounced, shows matched
messages with date and (when searching across everything) which recipe
they belonged to.

Verified locally: asked a real question, closed and reopened the panel
and confirmed the conversation reloaded, then searched a keyword from
that conversation and confirmed both the question and answer surfaced
in the results dropdown.

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

@@ -0,0 +1,53 @@
+import { NextRequest, NextResponse } from "next/server";
+import { z } from "zod";
+import { db, chatMessages, eq, and, isNull, desc, asc, ilike } from "@epicure/db";
+import { requireSession } from "@/lib/api-auth";
+
+const Schema = z.object({
+  recipeId: z.string().uuid().optional(),
+  // "general" restricts to the homepage cooking assistant (recipeId null);
+  // omit both recipeId and scope to search across everything.
+  scope: z.enum(["general"]).optional(),
+  q: z.string().max(200).optional(),
+  limit: z.coerce.number().int().min(1).max(100).default(30),
+});
+
+export async function GET(req: NextRequest) {
+  const { session, response } = await requireSession();
+  if (response) return response;
+
+  const { searchParams } = new URL(req.url);
+  const parsed = Schema.safeParse({
+    recipeId: searchParams.get("recipeId") ?? undefined,
+    scope: searchParams.get("scope") ?? undefined,
+    q: searchParams.get("q") ?? undefined,
+    limit: searchParams.get("limit") ?? undefined,
+  });
+  if (!parsed.success) {
+    return NextResponse.json({ error: "Validation error" }, { status: 400 });
+  }
+  const { recipeId, scope, q, limit } = parsed.data;
+
+  const conditions = [eq(chatMessages.userId, session!.user.id)];
+  if (recipeId) conditions.push(eq(chatMessages.recipeId, recipeId));
+  else if (scope === "general") conditions.push(isNull(chatMessages.recipeId));
+  if (q?.trim()) conditions.push(ilike(chatMessages.content, `%${q.trim()}%`));
+
+  const rows = await db.query.chatMessages.findMany({
+    where: and(...conditions),
+    orderBy: q?.trim() ? [desc(chatMessages.createdAt)] : [asc(chatMessages.createdAt)],
+    limit,
+    with: { recipe: { columns: { id: true, title: true } } },
+  });
+
+  return NextResponse.json({
+    data: rows.map((r) => ({
+      id: r.id,
+      role: r.role,
+      content: r.content,
+      createdAt: r.createdAt.toISOString(),
+      recipeId: r.recipeId,
+      recipeTitle: r.recipe?.title ?? null,
+    })),
+  });
+}

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

@@ -1,6 +1,7 @@
 import { NextRequest, NextResponse } from "next/server";
 import { z } from "zod";
 import { generateText } from "ai";
+import { db, chatMessages } from "@epicure/db";
 import { requireSession } from "@/lib/api-auth";
 import { applyRateLimit } from "@/lib/rate-limit";
 import { withAiQuota, resolveAiConfigOrError } from "@/lib/ai/ai-error";
@@ -46,5 +47,10 @@ export async function POST(req: NextRequest) {
   );
   if (!result.ok) return result.response;
 
+  void db.insert(chatMessages).values([
+    { id: crypto.randomUUID(), userId: session!.user.id, recipeId: null, role: "user", content: parsed.data.question },
+    { id: crypto.randomUUID(), userId: session!.user.id, recipeId: null, role: "assistant", content: result.data.text },
+  ]).catch((err) => console.error("[cooking-chat] failed to persist chat history", err));
+
   return NextResponse.json({ answer: result.data.text });
 }

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

@@ -6,7 +6,7 @@ import { applyRateLimit } from "@/lib/rate-limit";
 import { withAiQuota, resolveAiConfigOrError } from "@/lib/ai/ai-error";
 import { getModelConfigForUseCase } from "@/lib/ai/resolve-user-key";
 import { resolveModel } from "@/lib/ai/factory";
-import { db, recipes, eq, and } from "@epicure/db";
+import { db, recipes, chatMessages, eq, and } from "@epicure/db";
 import { getUserPrivateBio, buildUserBioContext } from "@/lib/ai/user-bio";
 import { hasQuantity } from "@/lib/fractions";
 
@@ -84,5 +84,10 @@ ${recipeContext}${bioContext}`,
   );
   if (!result.ok) return result.response;
 
+  void db.insert(chatMessages).values([
+    { id: crypto.randomUUID(), userId: session!.user.id, recipeId: recipe.id, role: "user", content: parsed.data.question },
+    { id: crypto.randomUUID(), userId: session!.user.id, recipeId: recipe.id, role: "assistant", content: result.data.text },
+  ]).catch((err) => console.error("[recipe-chat] failed to persist chat history", err));
+
   return NextResponse.json({ answer: result.data.text });
 }