diff --git a/apps/server/src/app.ts b/apps/server/src/app.ts
index 258d7a22b..4d935ea51 100644
--- a/apps/server/src/app.ts
+++ b/apps/server/src/app.ts
@@ -142,6 +142,10 @@ export async function createApp(
     c.set("owner", owner);
     await next();
   });
+  app.delete("/api/session", async (c) => {
+    await auth.revoke(c.req.header("authorization"));
+    return c.json({ ok: true });
+  });
   app.get("/api/workspace", async (c) => {
     const [snapshot, reachable] = await Promise.all([
       workspace.snapshot(c.get("owner"), c.req.query("q")),
diff --git a/apps/server/src/auth.ts b/apps/server/src/auth.ts
index 2d4f73ede..5cf51cf21 100644
--- a/apps/server/src/auth.ts
+++ b/apps/server/src/auth.ts
@@ -30,15 +30,24 @@ export class Auth {
   }
   async owner(authorization?: string) {
     if (!authorization?.startsWith("Bearer ")) throw new AppError("Sign in to OpenMuse", 401);
+    const id = digest(authorization.slice(7)).toString("hex");
     const session = await this.db.get<{ owner: string; expiresAt: number }>(
       "system",
       "sessions",
-      digest(authorization.slice(7)).toString("hex"),
+      id,
     );
-    if (!session || session.expiresAt < Date.now())
+    if (!session || session.expiresAt < Date.now()) {
+      // Expired sessions can never be valid again, so drop the row instead of keeping it forever.
+      // Best-effort: a failed cleanup must not turn the rejection into a 5xx.
+      if (session) await this.db.remove("system", "sessions", id).catch(() => {});
       throw new AppError("Session expired. Sign in again.", 401);
+    }
     return session.owner;
   }
+  async revoke(authorization?: string) {
+    if (authorization?.startsWith("Bearer "))
+      await this.db.remove("system", "sessions", digest(authorization.slice(7)).toString("hex"));
+  }
   sign(owner: string, path: string) {
     const expires = String(Date.now() + 15 * 60 * 1000);
     const signature = createHmac("sha256", this.signingKey)
diff --git a/tests/api.test.ts b/tests/api.test.ts
index 6ea94208b..4c98ab6bd 100644
--- a/tests/api.test.ts
+++ b/tests/api.test.ts
@@ -1,4 +1,5 @@
 import assert from "node:assert/strict";
+import { createHash } from "node:crypto";
 import { mkdtemp, rm } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
@@ -61,6 +62,55 @@ test("API protects private data and rejects unrelated web origins", async () =>
     403,
   );
 });
+test("signing out revokes only the current session", async () => {
+  const signIn = await app.request("/api/session", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: "{}",
+  });
+  const revoked = (await signIn.json()).token;
+  const auth = { Authorization: `Bearer ${revoked}` };
+  assert.equal(
+    (await app.request("/api/session", { method: "DELETE", headers: auth })).status,
+    200,
+  );
+  assert.equal((await app.request("/api/workspace", { headers: auth })).status, 401);
+  assert.equal(
+    (await app.request("/api/session", { method: "DELETE", headers: auth })).status,
+    401,
+  );
+  assert.equal((await app.request("/api/workspace", { headers: headers() })).status, 200);
+});
+test("an expired session is rejected and its row is removed", async () => {
+  const signIn = await app.request("/api/session", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: "{}",
+  });
+  const expired = (await signIn.json()).token;
+  const id = createHash("sha256").update(expired).digest("hex");
+  await db.put("system", "sessions", { id, owner: "local-user", expiresAt: Date.now() - 1 });
+  const response = await app.request("/api/workspace", {
+    headers: { Authorization: `Bearer ${expired}` },
+  });
+  assert.equal(response.status, 401);
+  assert.equal(await db.get("system", "sessions", id), null);
+});
+test("an expired session still returns 401 when its cleanup fails", async (t) => {
+  const signIn = await app.request("/api/session", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: "{}",
+  });
+  const expired = (await signIn.json()).token;
+  const id = createHash("sha256").update(expired).digest("hex");
+  await db.put("system", "sessions", { id, owner: "local-user", expiresAt: Date.now() - 1 });
+  t.mock.method(db, "remove", () => Promise.reject(new Error("db unavailable")));
+  const response = await app.request("/api/workspace", {
+    headers: { Authorization: `Bearer ${expired}` },
+  });
+  assert.equal(response.status, 401);
+});
 test("file operations recover a published PDF when metadata persistence fails", async (t) => {
   const owner = "file-recovery";
   const bytes = await createSamplePdf();