diff --git a/frontend/src/test/antispamMenu.test.ts b/frontend/src/test/antispamMenu.test.ts
new file mode 100644
index 0000000..f5558e7
--- /dev/null
+++ b/frontend/src/test/antispamMenu.test.ts
@@ -0,0 +1,57 @@
+// The antispam plugin's Actions-menu bundle (plugins/webmail_plugin_antispam).
+// Plugin bundles are plain ESM with a documented mount contract, so they can be
+// driven directly. This one earns a test: its decision table is small but has
+// been wrong twice, most recently hiding "Mark as not spam" on exactly the
+// message a user needs it for — one they had marked as spam by mistake.
+
+import { describe, expect, it } from "vitest";
+
+// Plugin bundles are untyped plain ESM by contract (docs/plugins.md §8) and
+// live outside the frontend package, so there is no declaration to find.
+// @ts-expect-error - untyped plugin bundle
+import mount from "../../../plugins/webmail_plugin_antispam/webmail_plugin_antispam/ui/menu.js";
+
+function ctxWith(special_use: string | null, learned: string | null) {
+  return {
+    api: {
+      pluginFetch: async () => ({
+        message_id: "m1",
+        special_use,
+        verdict: learned ? { learned } : null,
+      }),
+    },
+  };
+}
+
+async function render(special_use: string | null, learned: string | null): Promise<string> {
+  const el = document.createElement("div");
+  mount(el, ctxWith(special_use, learned), { messageId: "m1" });
+  await new Promise((r) => setTimeout(r, 0)); // the bundle fetches before rendering
+  return el.textContent ?? "";
+}
+
+describe("antispam Actions-menu item", () => {
+  it("offers Mark as Spam on untouched inbox mail", async () => {
+    expect(await render("inbox", null)).toBe("Mark as Spam");
+  });
+
+  it("offers Mark as not spam in the spam folder", async () => {
+    expect(await render("junk", null)).toBe("Mark as not spam");
+  });
+
+  it("still offers Mark as not spam for a message the user marked as spam", async () => {
+    // The regression: a message in the spam folder that was taught "spam" is
+    // precisely the one someone needs to correct, so the action must stay.
+    expect(await render("junk", "spam")).toBe("Mark as not spam");
+  });
+
+  it("suppresses only the lesson already taught", async () => {
+    expect(await render("inbox", "spam")).toBe("Marked as spam");
+  });
+
+  it("shows nothing where no move is a verdict about spam", async () => {
+    for (const folder of ["sent", "drafts", "trash", null]) {
+      expect(await render(folder, null)).toBe("");
+    }
+  });
+});
diff --git a/plugins/webmail_plugin_antispam/webmail_plugin_antispam/ui/menu.js b/plugins/webmail_plugin_antispam/webmail_plugin_antispam/ui/menu.js
index 70ec52f..7faec9a 100644
--- a/plugins/webmail_plugin_antispam/webmail_plugin_antispam/ui/menu.js
+++ b/plugins/webmail_plugin_antispam/webmail_plugin_antispam/ui/menu.js
@@ -25,18 +25,21 @@ export default function mount(el, ctx, props) {
     }
     if (disposed || !data) return;
 
-    // Already taught: show it, greyed, rather than offering the same lesson.
+    // The folder decides which action is on offer — FIRST. A message sitting in
+    // the spam folder offers "not spam" no matter what it was taught, because
+    // that is exactly the message someone needs to correct.
+    const action = MEANINGFUL[data.special_use];
+    if (!action) return;
+
+    // Only suppress the lesson we already taught, never its opposite.
     const learned = data.verdict && data.verdict.learned;
-    if (learned) {
+    if (learned === action.verdict) {
       el.innerHTML = `<button class="wm-menu-item" disabled>${
         learned === "spam" ? "Marked as spam" : "Marked as not spam"
       }</button>`;
       return;
     }
 
-    const action = MEANINGFUL[data.special_use];
-    if (!action) return;
-
     el.innerHTML = `<button class="wm-menu-item">${action.label}</button>`;
     el.querySelector("button").addEventListener("click", async () => {
       try {