diff --git a/README.md b/README.md
index 25f0ae5..8083be0 100644
--- a/README.md
+++ b/README.md
@@ -201,7 +201,7 @@ await fetch(refreshEndpoint, {
 | `"secret"`         | Valid `default` secret key      | Server-to-server, internal calls                    |
 | `"none"`           | None                            | Open endpoints, wrappers that handle their own auth |
 
-Array syntax (`auth: ["user", "secret"]`) accepts multiple auth methods — first match wins. An absent credential falls through to the next mode; a present-but-invalid JWT rejects the request (no silent downgrade).
+Array syntax (`auth: ["user", "secret"]`) accepts multiple auth methods — first match wins. An absent credential falls through to the next mode; a present-but-invalid JWT rejects the request (no silent downgrade). Because `"none"` matches every request, it is only accepted on its own or as the last entry of a list (`auth: ["user", "none"]` — optional user).
 
 Named key validation: `auth: "publishable:web_app"` or `auth: "secret:automations"` validates against a specific named key in `SUPABASE_PUBLISHABLE_KEYS` or `SUPABASE_SECRET_KEYS`. Bare `auth: "secret"` (or `"publishable"`) matches only the `default` key; use the wildcard `auth: "secret:*"` to accept any key in the set. See [`docs/auth-modes.md`](docs/auth-modes.md).
 
diff --git a/docs/api-reference.md b/docs/api-reference.md
index 9881fd3..ef18cca 100644
--- a/docs/api-reference.md
+++ b/docs/api-reference.md
@@ -459,6 +459,33 @@ type AuthModeWithKey = AuthMode | `publishable:${string}` | `secret:${string}`
 
 Extended auth mode with named key support. Examples: `'publishable:web'`, `'secret:*'`, `'secret:internal'`. The bare form (`'publishable'` / `'secret'`) matches only the `default` key; `:*` accepts any key in the set.
 
+### CredentialedAuthMode
+
+```ts
+type CredentialedAuthMode = Exclude<AuthModeWithKey, 'none'>
+```
+
+Every `AuthModeWithKey` except `'none'`, keyed forms included.
+
+### AuthConfig
+
+```ts
+type AuthConfig =
+  | 'none'
+  | CredentialedAuthMode
+  | [CredentialedAuthMode, ...CredentialedAuthMode[]]
+  | [CredentialedAuthMode, ...CredentialedAuthMode[], 'none']
+```
+
+The accepted shape of the `auth` option. `'none'` matches every request, so the type allows it on its own or as the last entry of a list, and nowhere else — `['none']` says nothing that a bare `'none'` doesn't, and a mode placed after `'none'` can never be reached. A single mode needs no wrapping array: `'user'` and `['user']` are the same configuration.
+
+```ts
+withSupabase({ auth: 'user' }, handler) // one mode
+withSupabase({ auth: ['secret', 'user'] }, handler) // first match wins
+withSupabase({ auth: ['user', 'none'] }, handler) // optional user
+withSupabase({ auth: 'none' }, handler) // no credentials required
+```
+
 ### Allow / AllowWithKey (deprecated aliases)
 
 `Allow` and `AllowWithKey` are kept as deprecated aliases for `AuthMode` and `AuthModeWithKey`. Prefer the `Auth*` names — the legacy ones will be removed in a future major release.
@@ -480,7 +507,7 @@ interface SupabaseContext<Database = unknown> {
 
 ```ts
 interface WithSupabaseConfig {
-  auth?: AuthModeWithKey | AuthModeWithKey[] // default: 'user'
+  auth?: AuthConfig // default: 'user'
   /** @deprecated use `auth` instead — will be removed in a future major release */
   allow?: AuthModeWithKey | AuthModeWithKey[]
   env?: Partial<SupabaseEnv>
diff --git a/docs/auth-modes.md b/docs/auth-modes.md
index b7e08f9..603326a 100644
--- a/docs/auth-modes.md
+++ b/docs/auth-modes.md
@@ -128,7 +128,7 @@ Use `none` for health checks, public APIs, or when you handle auth yourself insi
 
 ## Array syntax (multiple modes)
 
-Accept multiple auth methods. Modes are tried in order — the first match wins.
+Accept multiple auth methods. Modes are tried in order — the first match wins. The array is for lists only: a single mode is written unwrapped (`auth: 'user'`), though `auth: ['user']` means the same thing.
 
 ```ts
 import { withSupabase } from '@supabase/server'
@@ -155,6 +155,15 @@ export default {
 
 A request with a valid JWT matches `'user'`. A request with a valid secret key matches `'secret'`. A request with neither is rejected.
 
+**Where `'none'` can go.** `'none'` matches every request, so it only earns its place as the **last** entry of a list — `auth: ['user', 'none']` is "a user if one is signed in, anonymous otherwise." Anything after it is unreachable, and a list of just `['none']` says nothing that a bare `auth: 'none'` doesn't. Both are type errors:
+
+```ts
+withSupabase({ auth: ['user', 'none'] }, handler) // ✅ optional user
+withSupabase({ auth: 'none' }, handler) // ✅ open endpoint
+withSupabase({ auth: ['none'] }, handler) // ❌ use the bare 'none'
+withSupabase({ auth: ['none', 'user'] }, handler) // ❌ 'user' is unreachable
+```
+
 **Fallthrough vs rejection.** A mode is only "tried" when its credential is actually present. A request with no `Authorization` header moves on to the next mode. But if a JWT _is_ present and fails verification (malformed, expired, wrong signature, or missing a `sub` claim), the request is rejected immediately with `InvalidCredentialsError` — it will not silently fall through to `'publishable'`, `'secret'`, or `'none'`. The same rule applies on the API-key side: `'publishable'` and `'secret'` fall through only when no `apikey` header is sent. This prevents a bad credential from being downgraded to a less-privileged auth mode.
 
 ## Named key syntax
diff --git a/skills/supabase-server/SKILL.md b/skills/supabase-server/SKILL.md
index e2a020d..9cbb266 100644
--- a/skills/supabase-server/SKILL.md
+++ b/skills/supabase-server/SKILL.md
@@ -207,6 +207,8 @@ Bare `auth: 'secret'` matches only the `default` key. Use `auth: 'secret:name'`
 
 **On `auth: ['user', 'none']`.** A stale or malformed JWT on such an endpoint is rejected with `InvalidCredentialsError` — it is not silently downgraded to anonymous. Callers that might hold a cached/expired token should either omit the `Authorization` header entirely or refresh before calling. If the goal is "anonymous unless a valid user is signed in," this is the correct behavior; if the goal is truly "accept anything," use `auth: 'none'` on its own.
 
+**`'none'` goes last, or alone.** It matches every request, so the type accepts it only as the final entry of a list (`['user', 'none']`) or on its own (`'none'`). `['none']` and `['none', 'user']` are type errors — write the bare `'none'` for the first, and put `'none'` last for the second.
+
 ## Edge Function recipes
 
 ### Function-to-function calls
diff --git a/src/index.ts b/src/index.ts
index 62d5fc6..a4e039b 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -106,10 +106,12 @@ export type {
 export type {
   Allow,
   AllowWithKey,
+  AuthConfig,
   AuthMode,
   AuthModeWithKey,
   AuthResult,
   ClientAuth,
+  CredentialedAuthMode,
   CreateAdminClientOptions,
   CreateContextClientOptions,
   Credentials,
diff --git a/src/types.test.ts b/src/types.test.ts
new file mode 100644
index 0000000..2ff1d62
--- /dev/null
+++ b/src/types.test.ts
@@ -0,0 +1,68 @@
+import { describe, expectTypeOf, it } from 'vitest'
+
+import type { AuthConfig, WithSupabaseConfig } from './types.js'
+
+/**
+ * `AuthConfig` is enforced by `tsc`, not by vitest: the `@ts-expect-error`
+ * lines below fail `pnpm typecheck` if the type ever starts accepting an
+ * ordering it shouldn't, and fail it just as loudly if it starts rejecting
+ * one it should accept (an unused `@ts-expect-error` is itself an error).
+ */
+describe('AuthConfig', () => {
+  it('accepts a single mode unwrapped, keyed or not', () => {
+    expectTypeOf<'user'>().toExtend<AuthConfig>()
+    expectTypeOf<'secret'>().toExtend<AuthConfig>()
+    expectTypeOf<'publishable:mobile'>().toExtend<AuthConfig>()
+    expectTypeOf<'secret:*'>().toExtend<AuthConfig>()
+  })
+
+  it('accepts the wrapped form of a single mode too', () => {
+    const bare: AuthConfig = 'user'
+    const wrapped: AuthConfig = ['user']
+    void bare
+    void wrapped
+  })
+
+  it('accepts an ordered list of credentialed modes', () => {
+    const ordered: AuthConfig = ['secret', 'user']
+    const keyed: AuthConfig = ['user', 'publishable:web_app', 'secret:*']
+    void ordered
+    void keyed
+  })
+
+  it('accepts bare "none", and "none" as the last entry of a list', () => {
+    const bare: AuthConfig = 'none'
+    const optionalUser: AuthConfig = ['user', 'none']
+    const optionalAnything: AuthConfig = ['user', 'secret:*', 'none']
+    void bare
+    void optionalUser
+    void optionalAnything
+  })
+
+  it('rejects "none" as a list of one — a bare "none" says the same thing', () => {
+    // @ts-expect-error "none" needs a credentialed mode before it
+    const only: AuthConfig = ['none']
+    void only
+  })
+
+  it('rejects modes placed after "none", which can never be reached', () => {
+    // @ts-expect-error "none" matches every request, so nothing follows it
+    const unreachable: AuthConfig = ['none', 'user']
+    void unreachable
+    // @ts-expect-error same, with the trailing entry in final position
+    const sandwiched: AuthConfig = ['user', 'none', 'secret']
+    void sandwiched
+  })
+
+  it('rejects a repeated "none"', () => {
+    // @ts-expect-error only the last entry may be "none"
+    const twice: AuthConfig = ['user', 'none', 'none']
+    void twice
+  })
+
+  it('is the type of the `auth` option', () => {
+    expectTypeOf<WithSupabaseConfig['auth']>().toEqualTypeOf<
+      AuthConfig | undefined
+    >()
+  })
+})
diff --git a/src/types.ts b/src/types.ts
index fc3f054..26afffe 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -74,6 +74,45 @@ export type AuthModeWithKey =
  */
 export type AllowWithKey = AuthModeWithKey
 
+/**
+ * An auth mode that requires a credential — every {@link AuthModeWithKey}
+ * except `"none"`, keyed forms included.
+ *
+ * @category Types
+ */
+export type CredentialedAuthMode = Exclude<AuthModeWithKey, 'none'>
+
+/**
+ * Accepted shape of the `auth` option: one mode, or an ordered list of modes
+ * tried left to right.
+ *
+ * `"none"` accepts every request, so it only carries meaning as the last
+ * entry of a list — the modes before it are the ones that can produce an
+ * identity, and anything after it is unreachable. On its own in a list
+ * (`["none"]`) it says nothing that a bare `auth: 'none'` doesn't. So the
+ * type accepts `"none"` alone or in final position behind at least one
+ * credentialed mode, and nowhere else.
+ *
+ * A single mode needs no wrapping array — `"user"` and `["user"]` are the
+ * same configuration, and the unwrapped form is the one the union names
+ * first, so it is what shows up in editor completions.
+ *
+ * @example Every accepted form
+ * ```ts
+ * withSupabase({ auth: 'user' }, handler)              // one mode
+ * withSupabase({ auth: ['secret', 'user'] }, handler)  // first match wins
+ * withSupabase({ auth: ['user', 'none'] }, handler)    // optional user
+ * withSupabase({ auth: 'none' }, handler)              // no credentials required
+ * ```
+ *
+ * @category Types
+ */
+export type AuthConfig =
+  | 'none'
+  | CredentialedAuthMode
+  | [CredentialedAuthMode, ...CredentialedAuthMode[]]
+  | [CredentialedAuthMode, ...CredentialedAuthMode[], 'none']
+
 /**
  * Resolved Supabase environment configuration.
  *
@@ -255,14 +294,19 @@ export interface WithSupabaseConfig {
    * A mode falls through only when its credential is absent; a present-but-invalid
    * JWT short-circuits the chain with `InvalidCredentialsError`.
    *
+   * `"none"` matches unconditionally, so it belongs last in a list or on its
+   * own — see {@link AuthConfig}.
+   *
    * @defaultValue `"user"`
    */
-  auth?: AuthModeWithKey | AuthModeWithKey[]
+  auth?: AuthConfig
 
   /**
    * @deprecated Use {@link WithSupabaseConfig.auth} instead. The `allow` option
    * is kept for backward compatibility and will be removed in a future major release.
-   * When both `auth` and `allow` are provided, `auth` takes precedence.
+   * When both `auth` and `allow` are provided, `auth` takes precedence. It keeps
+   * the older, looser element type so code mid-migration still compiles; `auth`
+   * is where the {@link AuthConfig} ordering rule is enforced.
    */
   allow?: AuthModeWithKey | AuthModeWithKey[]
 
diff --git a/src/with-supabase.ts b/src/with-supabase.ts
index 349d8a5..52835c7 100644
--- a/src/with-supabase.ts
+++ b/src/with-supabase.ts
@@ -13,7 +13,11 @@ import {
 } from './core/parts/projections.js'
 import { withSupabaseAdminClient } from './middleware/admin-client/index.js'
 import { withSupabaseClient } from './middleware/client/index.js'
-import type { SupabaseContext, WithSupabaseConfig } from './types.js'
+import type {
+  AuthModeWithKey,
+  SupabaseContext,
+  WithSupabaseConfig,
+} from './types.js'
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 type AnyHandler = (req: Request, ctx: any) => Promise<Response>
@@ -65,7 +69,12 @@ void entryIsSound
 /** Whether every configured auth mode requires credentials, so an unauthenticated request never passes the gate. */
 function requiresCredentials(config: WithSupabaseConfig): boolean {
   const modes = config.auth ?? config.allow ?? 'user'
-  const list = Array.isArray(modes) ? modes : [modes]
+  // `auth` keeps `'none'` out of every position but the last; the deprecated
+  // `allow` still admits it anywhere, so this reads the widened element type
+  // and scans the whole list.
+  const list: readonly AuthModeWithKey[] = Array.isArray(modes)
+    ? modes
+    : [modes]
   return !list.includes('none')
 }