codexmachina
registry/nuxt-postgres-supabase-notes-resend

Notes / knowledge base on Nuxt 4, Postgres (Neon) and Supabase Auth with Resend

Notes / knowledge-base: user-owned notebooks, free-form tags, and per-note read/write sharing.

79 files, 3 tables and 82 lines of schema, verified 2026-08-23 on Nuxt 4, Postgres (Neon) and Supabase Auth.

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16 pinned upstream versions
clsx2.1.1nuxt4.5.2vaul1.1.2resend6.18.1shadcn4.16.1sonner2.0.7postgres3.4.9radix-ui1.6.7recharts3.10.1lucide-react1.28.0@supabase/ssr0.12.4tailwind-merge3.6.0tw-animate-css1.4.0@tanstack/react-table8.21.3@neondatabase/serverless1.1.0class-variance-authority0.7.1
Browserrequest
fetch
Nuxt 4routing + proxy
verify
Supabase Authsession
query
Postgres (Neon)pooled

request path. session validation runs in server components and route handlers, not at the edge

What you're getting

Nuxt 4

Nuxt 4 (framework mode): full-stack Vue SSR: client under app/ (Vite), server under server/ (Nitro), API as server/api/*.post.ts Nitro route handlers.

Postgres (Neon)

Postgres on Neon via Drizzle ORM and the postgres-js driver.

Supabase Auth

Supabase Auth: hosted identity (GoTrue) via the @supabase/ssr cookie client; email+password + OAuth.

Notes / knowledge base

Notes / knowledge-base: user-owned notebooks, free-form tags, and per-note read/write sharing.

Resend

Resend: transactional email (welcome/notification always; verify/reset when auth is self-hosted).

Setup

bun add nuxt vue drizzle-orm postgres @supabase/ssr @supabase/supabase-js
DATABASE_URLNeon pooled (-pooler) connection string
NEXT_PUBLIC_SUPABASE_URLNext: your Supabase project URL (RR: VITE_SUPABASE_URL · Nuxt: NUXT_PUBLIC_SUPABASE_URL)
NEXT_PUBLIC_SUPABASE_ANON_KEYNext: the project's anon/public key (RR: VITE_SUPABASE_ANON_KEY · Nuxt: NUXT_PUBLIC_SUPABASE_ANON_KEY)
SUPABASE_URLReact Router server-side (loaders): same project URL, read off process.env — never inlined into the client bundle
SUPABASE_ANON_KEYReact Router server-side: same anon key

Apply the schema with bunx drizzle-kit push

Initialization

Database client

server/lib/db.ts
import { drizzle } from "drizzle-orm/postgres-js";
import postgres from "postgres";

// Neon pooled endpoint = PgBouncer transaction mode → prepared statements off.
// ponytail: single module-level client; the serverless runtime + PgBouncer do
// the pooling, so no custom pool/globalThis singleton dance needed.
const client = postgres(process.env.DATABASE_URL!, { prepare: false });

export const db = drizzle({ client });

Notes app schema: notebooks, notes, tags & sharing

4 tables, 19 columns and 8 indexes and constraints, applied to a live Postgres (Neon) and asserted to materialize.

notebooks4 columns · 2 indexed
notes7 columns · 2 indexed
note_tags3 columns · 2 indexed
note_shares5 columns · 2 indexed

What this schema is built to answer

Everything in one notebook, live or archived

idx_note_notebook on notes.notebook_id scans a single notebook, and the is_archived boolean splits live from archived in the same predicate rather than in a second table.

The notebooks a user owns

idx_notebook_owner on notebooks.owner_id drives the sidebar; owner_id cascades from user, so a deleted account takes its notebooks and their notes with it.

The tag set on a note, already deduplicated

note_tags_note_tag_unique on (note_id, tag) leads with note_id for the read and rejects a repeated label on insert, so nothing downstream has to de-duplicate.

Who can see a note, and at what level

note_shares_note_user_unique on (note_id, shared_with) fetches a note's whole grant list from its leading column, and note_shares_permission_check pins each grant to read or write.

Deleting a note without leaving orphan tags or grants

note_tags.note_id and note_shares.note_id both reference notes with ON DELETE CASCADE, and notes cascade from notebooks in turn, so one DELETE clears the note's labels and every share of it.

Notebooks & notes

the owner-scoped notebook containers and the notes nested inside them, with archive support

Tags

free-form text labels attached to individual notes, deduplicated by a composite unique constraint

Sharing & permissions

per-note grants to other users with a CHECK-enforced read/write permission level

src/db/schema.ts
// === file: server/db/schema.ts ===
import { relations, sql } from "drizzle-orm";
import {
  boolean,
  check,
  index,
  pgTable,
  text,
  timestamp,
  unique,
  uuid,
} from "drizzle-orm/pg-core";
// Better Auth owns identity; we only reference its `user` table by id.
import { user } from "./auth-schema";

export const notebooks = pgTable(
  "notebooks",
  {
    id: uuid("id").primaryKey().defaultRandom(),
    ownerId: text("owner_id").notNull().references(() => user.id, { onDelete: "cascade" }),
    name: text("name").notNull(),
    createdAt: timestamp("created_at", { withTimezone: true }).notNull().defaultNow(),
  },
  (t) => [index("idx_notebook_owner").on(t.ownerId)],
);

export const notes = pgTable(
  "notes",
  {
    id: uuid("id").primaryKey().defaultRandom(),
    notebookId: uuid("notebook_id").notNull().references(() => notebooks.id, { onDelete: "cascade" }),
    authorId: text("author_id").notNull().references(() => user.id, { onDelete: "cascade" }),
    title: text("title").notNull(),
    body: text("body"),
    isArchived: boolean("is_archived").notNull().default(false),
    createdAt: timestamp("created_at", { withTimezone: true }).notNull().defaultNow(),
  },
  (t) => [index("idx_note_notebook").on(t.notebookId)],
);

export const noteTags = pgTable(
  "note_tags",
  {
    id: uuid("id").primaryKey().defaultRandom(),
    noteId: uuid("note_id").notNull().references(() => notes.id, { onDelete: "cascade" }),
    tag: text("tag").notNull(),
  },
  (t) => [unique("note_tags_note_tag_unique").on(t.noteId, t.tag)],
);

export const noteShares = pgTable(
  "note_shares",
  {
    id: uuid("id").primaryKey().defaultRandom(),
    noteId: uuid("note_id").notNull().references(() => notes.id, { onDelete: "cascade" }),
    sharedWith: text("shared_with").notNull().references(() => user.id, { onDelete: "cascade" }),
    permission: text("permission").notNull().default("read"),
    createdAt: timestamp("created_at", { withTimezone: true }).notNull().defaultNow(),
  },
  (t) => [
    unique("note_shares_note_user_unique").on(t.noteId, t.sharedWith),
    check("note_shares_permission_check", sql`${t.permission} in ('read','write')`),
  ],
);

export const notebooksRelations = relations(notebooks, ({ one, many }) => ({
  owner: one(user, { fields: [notebooks.ownerId], references: [user.id] }),
  notes: many(notes),
}));
export const notesRelations = relations(notes, ({ one, many }) => ({
  notebook: one(notebooks, { fields: [notes.notebookId], references: [notebooks.id] }),
  author: one(user, { fields: [notes.authorId], references: [user.id] }),
  tags: many(noteTags),
  shares: many(noteShares),
}));
export const noteTagsRelations = relations(noteTags, ({ one }) => ({
  note: one(notes, { fields: [noteTags.noteId], references: [notes.id] }),
}));
export const noteSharesRelations = relations(noteShares, ({ one }) => ({
  note: one(notes, { fields: [noteShares.noteId], references: [notes.id] }),
  user: one(user, { fields: [noteShares.sharedWith], references: [user.id] }),
}));

Deploy targets

✓ The right DB client for where you deploy: load-tested with concurrent queries against a live database. Edge needs the HTTP driver (no TCP); serverless needs a tiny pool.
src/lib/db.ts
import { drizzle } from "drizzle-orm/postgres-js";
import postgres from "postgres";

// Serverless: one connection per (short-lived) instance; Neon's pooler multiplexes.
export const sql = postgres(process.env.DATABASE_URL!, { prepare: false, max: 1 });
export const db = drizzle(sql);

The app UI

A working auth flow and a protected app shell, type-checked against the same verified wiring above. This is what codexmachina create scaffolds on top of the official Nuxt 4 starter.
app/components/nav-user.vue
<script setup lang="ts">
import { computed, onBeforeUnmount, onMounted, ref } from "vue"
import {
  EllipsisVerticalIcon,
  CircleUserRoundIcon,
  CreditCardIcon,
  BellIcon,
  LogOutIcon,
} from "lucide-vue-next"
import type { User } from "@supabase/supabase-js"
import { Avatar, AvatarFallback, AvatarImage } from "@/components/ui/avatar"
import {
  DropdownMenu,
  DropdownMenuContent,
  DropdownMenuGroup,
  DropdownMenuItem,
  DropdownMenuLabel,
  DropdownMenuSeparator,
  DropdownMenuTrigger,
} from "@/components/ui/dropdown-menu"
import { SidebarMenu, SidebarMenuButton, SidebarMenuItem, useSidebar } from "@/components/ui/sidebar"
import { Skeleton } from "@/components/ui/skeleton"
import { createClient } from "~~/lib/supabase-client"

// Supabase variant of the sidebar-footer user menu — the SAME shell every auth overlay reuses, wired
// to the browser Supabase client: getUser() on mount + onAuthStateChange to stay reactive across tabs,
// cookie-based sign-out.
const { isMobile } = useSidebar()
const supabase = createClient()

const user = ref<User | null>(null)
const loading = ref(true)
let unsubscribe: (() => void) | undefined

onMounted(async () => {
  const { data } = await supabase.auth.getUser()
  user.value = data.user
  loading.value = false
  const { data: listener } = supabase.auth.onAuthStateChange((_event, session) => {
    user.value = session?.user ?? null
  })
  unsubscribe = () => listener.subscription.unsubscribe()
})
onBeforeUnmount(() => unsubscribe?.())

const email = computed(() => user.value?.email ?? "")
const initials = computed(() => email.value.slice(0, 2).toUpperCase())
const avatarUrl = computed(() => {
  const url = user.value?.user_metadata?.avatar_url
  return typeof url === "string" ? url : undefined
})

async function handleSignOut() {
  await supabase.auth.signOut()
  navigateTo("/sign-in")
}
</script>
<template>
  <SidebarMenu>
    <SidebarMenuItem>
      <div v-if="loading" class="flex items-center gap-2 p-2">
        <Skeleton class="size-8 rounded-lg" />
        <Skeleton class="h-4 w-28 rounded-md" />
      </div>
      <DropdownMenu v-else-if="user">
        <DropdownMenuTrigger as-child>
          <SidebarMenuButton
            size="lg"
            class="data-[state=open]:bg-sidebar-accent data-[state=open]:text-sidebar-accent-foreground"
          >
            <Avatar class="size-8 rounded-lg grayscale">
              <AvatarImage v-if="avatarUrl" :src="avatarUrl" :alt="email" />
              <AvatarFallback class="rounded-lg">{{ initials }}</AvatarFallback>
            </Avatar>
            <div class="grid flex-1 text-left text-sm leading-tight">
              <span class="truncate font-medium">{{ email }}</span>
            </div>
            <EllipsisVerticalIcon class="ml-auto size-4" />
          </SidebarMenuButton>
        </DropdownMenuTrigger>
        <DropdownMenuContent
          class="min-w-56 rounded-lg"
          :side="isMobile ? 'bottom' : 'right'"
          align="end"
          :side-offset="4"
        >
          <DropdownMenuLabel class="p-0 font-normal">
            <div class="flex items-center gap-2 px-1 py-1.5 text-left text-sm">
              <Avatar class="size-8 rounded-lg">
                <AvatarImage v-if="avatarUrl" :src="avatarUrl" :alt="email" />
                <AvatarFallback class="rounded-lg">{{ initials }}</AvatarFallback>
              </Avatar>
              <div class="grid flex-1 text-left text-sm leading-tight">
                <span class="truncate font-medium">{{ email }}</span>
              </div>
            </div>
          </DropdownMenuLabel>
          <DropdownMenuSeparator />
          <DropdownMenuGroup>
            <DropdownMenuItem>
              <CircleUserRoundIcon />
              Account
            </DropdownMenuItem>
            <DropdownMenuItem>
              <CreditCardIcon />
              Billing
            </DropdownMenuItem>
            <DropdownMenuItem>
              <BellIcon />
              Notifications
            </DropdownMenuItem>
          </DropdownMenuGroup>
          <DropdownMenuSeparator />
          <DropdownMenuItem @click="handleSignOut">
            <LogOutIcon />
            Log out
          </DropdownMenuItem>
        </DropdownMenuContent>
      </DropdownMenu>
    </SidebarMenuItem>
  </SidebarMenu>
</template>

Email — verified (Resend)

✓ Audited with emailens — above our disclosed compatibility threshold across 21 email clients. Every template ships an unsubscribe link, a physical mailing address, and explicit lang/charset/contrast — the concrete set the audit checks for.
emails/welcome.mjml
<mjml lang="en">
  <mj-head>
    <mj-title>Welcome aboard</mj-title>
    <mj-attributes>
      <mj-all font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif" />
    </mj-attributes>
  </mj-head>
  <mj-body background-color="#f4f4f5">
    <mj-raw><div style="display:none;overflow:hidden;line-height:1px;opacity:0;max-height:0;max-width:0;">You're in — here's how to get started.</div></mj-raw>
    <mj-section background-color="#ffffff" padding="32px" border-radius="8px">
      <mj-column>
        <mj-text color="#111827" font-size="22px" font-weight="700">Welcome, {{name}}!</mj-text>
        <mj-text color="#374151" font-size="15px" line-height="24px">Thanks for signing up. Your account is ready to go.</mj-text>
        <mj-text color="#374151" font-size="15px" line-height="24px">If you have any questions, just reply to this email — a real person reads it.</mj-text>
        <mj-raw>
          <table role="presentation" cellpadding="0" cellspacing="0" style="margin:24px 0;">
            <tr>
              <td style="border-radius:6px;background-color:#111827;" align="center">
                <a href="{{ctaUrl}}" style="display:inline-block;padding:12px 20px;font-size:15px;font-weight:600;color:#ffffff;background-color:#111827;border-radius:6px;text-decoration:none;font-family:-apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;">Go to your dashboard</a>
              </td>
            </tr>
          </table>
        </mj-raw>
        <mj-divider border-color="#e5e7eb" />
        <mj-text color="#4b5563" font-size="12px" line-height="18px">Acme Inc, 548 Market St PMB 12345, San Francisco, CA 94104</mj-text>
        <mj-text color="#4b5563" font-size="12px" line-height="18px"><a href="{{unsubscribeUrl}}" style="color:#4b5563;text-decoration:underline;">Unsubscribe</a></mj-text>
      </mj-column>
    </mj-section>
  </mj-body>
</mjml>

Decisions and compatibility

note

Client/server split: the DB client, Drizzle schema, records, and webhooks are server-side (server/). The `@/` alias is the client root (app/); server code reaches shared modules via Nuxt's `~~` rootDir alias (e.g. `~~/server/db/schema`).

note

The API layer is Nitro, Nuxt's server engine: endpoints are server/api/*.post.ts route handlers, and auth mounts as a Nitro catch-all that delegates to the auth library's framework-agnostic web handler.

note

Nuxt auto-imports components and composables at runtime, but the emitted server code imports h3 helpers (defineEventHandler, toWebRequest) EXPLICITLY — the one deliberate idiom trade so the handlers type-check under standalone tsc instead of relying on the auto-import magic.

note

Session gating runs in a Nitro server middleware (server/middleware/), which fires on every SSR and API request — the true security boundary, and a real server-side session check rather than a cookie-existence peek.

note

prepare: false is mandatory — Neon's pooled endpoint is PgBouncer in transaction mode, where server-side prepared statements break across the pool.

note

Drizzle is paired here (not Prisma): Prisma's prepared-statement reliance is incompatible with transaction-mode pooling.

note

Hosted: Supabase owns identity in its managed auth.users. This stack emits a LOCAL `user` mirror (db/auth-schema.ts) so app-type schemas can foreign-key `user` directly — keep it in sync with a Supabase trigger on auth.users (insert/update → public.user). The drizzle migration only owns the mirror table's shape, not the trigger.

note

Sessions are cookie-based (@supabase/ssr): the proxy refreshes them on every request; Server Components read the user via supabase.auth.getUser().

note

note_tags enforces a unique constraint on (note_id, tag), so duplicate tags per note are rejected at the DB level rather than in application code.

note

note_shares carries a CHECK constraint limiting permission to 'read' or 'write', and a composite unique on (note_id, shared_with) — one share row per user per note, updated in place rather than appended.

How this stack fits together

On Nuxt 4 this stack puts its Postgres (Neon) client at server/lib/db.ts and the Supabase Auth instance at app/middleware/auth.ts and session checks in server/middleware/supabase.ts. Those are the paths this framework's adapter actually emits, not a shared convention: the same Notes / knowledge base schema and the same Supabase Auth wiring land somewhere different on each of the other frameworks in the registry.

Supabase Auth owns its identity tables in the same database as notebooks, notes, note_tags and note_shares, so the foreign keys reference the local user row directly and a delete cascades through them. No mirror, no webhook, and no window where the two stores disagree.

Postgres (Neon) stores those surrogate keys as uuid, so every foreign key across the 4 tables and 19 columns below is a uuid column. The migration was applied to a live Postgres (Neon) and the tables asserted, not just type-checked.

Resend is additive here: it does not change the Notes / knowledge base tables, it adds send helpers and templates that Supabase Auth calls for its verification and reset flows. The base cell without Resend is the same schema with those files removed.

Notes / knowledge base

Access here is note-shaped, not notebook-shaped. notebooks has a single owner_id and no share table of its own; note_shares grants another user read or write on one note at a time, constrained by note_shares_permission_check to exactly read or write and deduplicated by note_shares_note_user_unique on (note_id, shared_with). That composite unique turns a grant into an upsert — promoting someone from read to write updates the existing row instead of stacking a second one — but it also means a whole notebook cannot be handed over in one statement: collaborating on twenty notes is twenty rows. Notes carry two identity columns that are easy to conflate. notebook_id points at the container, whose owner_id decides who the notebook belongs to; author_id points at whoever wrote the note.

They are independent foreign keys into user, so one notebook can accumulate notes written by different people and an authorship query never walks up to the container. body is nullable — a note is a title until someone writes into it — and is_archived is a plain boolean defaulting to false rather than a deleted_at timestamp, so archiving is reversible; since no partial index excludes them, archived notes still sit in idx_note_notebook and every notebook read filters them out in the predicate. Tags are free text with no tag table behind them: note_tags holds (note_id, tag) and note_tags_note_tag_unique rejects the same label twice on one note, so a note's tag list arrives already deduplicated.

The leading column of that unique is note_id, which makes the tags on this note cheap and leaves the reverse — every note carrying one label — as a scan. note_shares has the same asymmetry: its unique leads with note_id, so who can see this note is indexed while what has been shared with me is not. Both are one CREATE INDEX away; the schema simply does not presume you need them before you build the surface that asks.

Nuxt 4

Nuxt 4 in framework mode is the one stack here with two roots. Client code lives under app/ and is what `@/` points at (Vite, Vue single-file components); server code lives under server/ and is run by Nitro, Nuxt's server engine. The database layer is server-side, so initCode writes server/lib/db.ts and the schema, record modules and webhooks land under server/db/ and server/api/ — server modules reach each other through Nuxt's `~~` rootDir alias (`~~/server/lib/db`, `~~/server/db/schema`), never through `@/`. That split earns its keep with secrets: the Resend send client belongs to ~~/server/lib/email, and nothing under app/ can import it by accident. The API layer is Nitro rather than a React-shaped route file.

server/api/webhooks/polar.post.ts is a POST endpoint; auth mounts as the catch-all server/api/auth/[...all].ts, which adapts the H3 event with toWebRequest(event) and hands the resulting web Request to the auth library's framework-agnostic handler. Nuxt auto-imports defineEventHandler and its siblings at runtime, but the emitted server files import them from h3 explicitly — one deliberate idiom trade so every handler type-checks under standalone tsc. Session gating is a Nitro server middleware at server/middleware/auth.ts. It fires on every SSR render and every API request, filters on pathname prefixes (/dashboard, /settings), performs the real auth.api.getSession() lookup, and answers with sendRedirect(event, "/sign-in", 302). Because Nitro sits in front of both the rendered page and the endpoints, that is a genuine security boundary rather than a cheap pre-render bounce.

On the client, Vue does its own thing: the auth binding exposes signIn/signUp/useSession as Vue refs, screens are .vue components under app/pages/ (sign-in.vue, dashboard/[id].vue), chrome lives in app/components/ and app/layouts/, and SPA-side guards are app/middleware/*.ts. The design system is shadcn-vue on reka-ui — a real re-port, not the React components wearing new names — and it is checked with vue-tsc, since plain tsc cannot parse an SFC.

Postgres (Neon)

Postgres here is Neon reached through postgres-js, with Drizzle's pg-core dialect on top: drizzle({ client }) over a single module-level postgres(DATABASE_URL, { prepare: false }). That flag is not a preference. Neon's pooled (-pooler) endpoint is PgBouncer in transaction mode, where a backend is handed to a different session between statements, so server-side prepared statements break across the pool — and the same constraint is why this axis pairs with Drizzle rather than Prisma. One client per module is enough: PgBouncer and the runtime do the pooling, so there is no globalThis singleton dance. The schemas built on this dialect make three recurring type decisions. Primary keys are uuid(...).primaryKey().defaultRandom(), so ids come from the database. Timestamps are timestamp(..., { withTimezone: true }).defaultNow() — timestamptz, an absolute instant.

Closed value sets are text plus a CHECK constraint rather than pgEnum, so shipping a new role or subscription status is an ordinary constraint change instead of an ALTER TYPE migration. Counters are bigint({ mode: "number" }), and Better Auth's text user.id is referenced as text by the app tables rather than recast. Operationally, transaction-mode pooling forbids anything that spans statements on one backend: LISTEN/NOTIFY, session-scoped SET, advisory-lock sessions, WITH HOLD cursors. Those paths use Neon's direct endpoint instead. The connection client also changes with the deploy target — max: 1 per short-lived serverless instance, a real reused pool (max 10, idle_timeout 20) in a long-running Node process, and on Cloudflare Workers postgres-js is replaced outright by @neondatabase/serverless over HTTP, because Workers have no TCP sockets.

The capability that exists only on this side of the matrix is row-level security. Multi-tenant schemas ship ENABLE plus FORCE ROW LEVEL SECURITY with policies keyed on current_setting('app.current_org_id', true), which withTenant() sets per transaction — unset context yields no rows, so isolation fails closed inside the database rather than in application code. It requires a dedicated NOBYPASSRLS role: Neon's default neondb_owner carries BYPASSRLS, and connecting as it makes every policy silently inert.

Supabase Auth

Supabase Auth is a hosted service — GoTrue — that your app reaches over cookies rather than an SDK session object. Credentials and the canonical user records live in Supabase's managed auth.users schema. What lands in your own database is a mirror: db/auth-schema.ts declares user keyed by the Supabase auth uid (text; varchar(255) on MySQL) with email, full name, avatar URL and timestamps, so app-type schemas can foreign-key user exactly as they would under a self-hosted auth. Unlike the Clerk fragment, no sync webhook is emitted here, because Supabase's own trigger mechanism is the intended path: a trigger on auth.users writing into public.user lives in the Supabase project, not in the drizzle migration.

The migration owns the mirror's column shape and nothing else, so wiring that trigger is a step you take before those foreign keys mean anything. The mechanic that actually shapes this adapter is cookie refresh. @supabase/ssr rotates the auth token, and a rotated cookie only reaches the browser if something writes it onto the outgoing response — which is why every framework branch is built around the same getAll/setAll pair, wired to whatever that framework calls a cookie jar. Next's src/proxy.ts rebuilds the NextResponse inside setAll before calling getUser().

React Router has no middleware layer, so app/lib/supabase/server.ts constructs the client per request and returns { supabase, headers }, and the protected layout route attaches those headers to both exits — the redirect and the pass-through — so a refresh that happened during a guard is not lost. Nuxt's server/utils/supabase.ts binds the client to the h3 event and writes through setCookie, with a Nitro middleware doing the guard. Every decision point calls supabase.auth.getUser(), never getSession(): getSession reads whatever the cookie claims, getUser revalidates it against Supabase. Because a browser client is emitted alongside the server one, the auth screens are real forms calling supabase.auth.signInWithPassword rather than a hosted widget, and the sidebar's user menu subscribes to onAuthStateChange. Two consequences to plan around.

The anon key is public by design and is inlined into the client bundle under whichever prefix the framework demands (NEXT_PUBLIC_, VITE_, NUXT_PUBLIC_), so protection has to come from row-level security on Supabase's side, not from keeping the key quiet. And every guard is a network call to Supabase, not a local query — cheap, but not free, and on the path of every protected request.

Resend

Resend covers two jobs: the transactional templates and the module that sends them. `emailTemplates` branches on `framework.slug` — Next.js and React Router get React Email components under `emails/` (`welcome.tsx`, `notification.tsx`, plus `verify-email.tsx` and `reset-password.tsx` when the auth is library-kind), Nuxt gets the same four as `.mjml` files. Both serializations read subject, preview, heading, body lines and CTA label from the shared `EMAIL_COPY` map, so the words are identical and only the markup differs. Every template closes with the `BRAND_ADDRESS` mailing address and an Unsubscribe link, and the React path sets `lang="en"`, a non-empty `<title>` and an explicit `<meta charSet="utf-8">`. `emailSend` emits `lib/email.ts`.

The provider client is built lazily inside `resendClient()` (`client ??= new Resend(process.env.RESEND_API_KEY)`) because `new Resend(undefined)` throws "Missing API key" — at module scope that throw fires at import time, which is exactly when a framework build imports this file to collect page data, so `next build` would fail on any machine holding only runtime secrets. `FROM` reads `EMAIL_FROM` and falls back to Resend's sandbox sender. On Next and React Router each sender awaits `render(WelcomeEmail(props))` from `@react-email/render` — async in the installed 2.1.0 — then calls `resendClient().emails.send({ from, to, subject, html })`.

On Nuxt the templates are inlined as string constants instead, `fill()` substitutes their `{{token}}` placeholders, `mjml2html(src, { validationLevel: "soft" })` compiles them and throws on any returned `errors`, and an ambient `mjml.d.ts` ships alongside because mjml@5 carries no type declarations. Which senders exist is gated on `auth.kind`. Hosted auth gets `sendWelcome` and `sendNotification` only. A library auth additionally gets `sendVerifyEmail` and `sendResetPassword` — the two functions its own config imports back out of this module to fill Better Auth's `emailAndPassword.sendResetPassword` and `emailVerification.sendVerificationEmail` hooks. A hosted provider sends those mails from its own infrastructure.