diff --git a/eid/aut.ts b/eid/aut.ts
new file mode 100644
index 0000000..569e73f
--- /dev/null
+++ b/eid/aut.ts
@@ -0,0 +1,32 @@
+import type { Aut, Usr } from "./typ.ts"
+import { DocR, DocU, coll } from "./db.ts"
+import { is_aut, is_in } from "./is.ts"
+
+export async function aut(
+): DocR<Omit<Aut, "_id">> {
+	return await coll.aut.findOne({ _id: 1 }, { projection: { _id: 0 } }) ?? null
+}
+
+export async function aut_f(
+	usr: Usr["_id"],
+): Promise<(keyof Omit<Aut, "_id">)[]> {
+	const a = await aut()
+	if (!a) return []
+	const l: (keyof Omit<Aut, "_id">)[] = []
+	if (is_in(a.sup, usr)) l.push("sup")
+	if (is_in(a.aut, usr)) l.push("aut")
+	if (is_in(a.wsl, usr)) l.push("wsl")
+	if (is_in(a.lit, usr)) l.push("lit")
+	return l
+}
+
+export async function aut_u(
+	a: Omit<Aut, "_id">,
+): DocU {
+	if (!is_aut({ _id: 1, ...a })) return null
+	try {
+		const { matchedCount, modifiedCount } = await coll.aut.updateOne({ _id: 1 }, { $set: a })
+		if (matchedCount > 0) return modifiedCount > 0 ? 1 : 0
+		else return null
+	} catch { return null }
+}
diff --git a/eid/is.ts b/eid/is.ts
index 7047a71..6b596c9 100644
--- a/eid/is.ts
+++ b/eid/is.ts
@@ -36,6 +36,12 @@ export function is_idl(
 ) {
 	return idl.length <= len && idl.every(is_id)
 }
+export function is_in(
+	idl: Id["_id"][],
+	id: Id["_id"],
+) {
+	return idl.includes(id)
+}
 export function is_utc(
 	utc: number,
 ) {
diff --git a/tst/eid.test.ts b/tst/eid.test.ts
index a462863..97e3fdb 100644
--- a/tst/eid.test.ts
+++ b/tst/eid.test.ts
@@ -3,7 +3,8 @@ import { usr_c, usr_d, usr_r, usr_u } from "../eid/usr.ts"
 import { soc_c, soc_d, soc_r, soc_u } from "../eid/soc.ts"
 import { agd_c, agd_d, agd_r, agd_u } from "../eid/agd.ts"
 import { assertEquals } from "./mod.test.ts"
-import { msg_c, msg_f, msg_r, msg_u } from "../eid/msg.ts";
+import { msg_c, msg_f, msg_r, msg_u } from "../eid/msg.ts"
+import { aut, aut_f, aut_u } from "../eid/aut.ts"
 
 await db("tst", true)
 
@@ -58,3 +59,9 @@ Deno.test("msg", async () => {
 	assertEquals("msg2", m2?.msg)
 	assertEquals([m1?._id, m2?._id], (await msg_f(coll.wsl)).map(m => m._id))
 })
+
+Deno.test("aut", async () => {
+	assertEquals({ sup: [1, 2], aut: [2], wsl: [], lit: [] }, await aut())
+	assertEquals(1, await aut_u({ sup: [1, 2], aut: [2, 3], wsl: [3, 4], lit: [3, 4] }))
+	assertEquals(["aut", "wsl", "lit"], await aut_f(3))
+})