diff --git a/src/routes/notes.js b/src/routes/notes.js
index 8248dc1..c2dcc9b 100644
--- a/src/routes/notes.js
+++ b/src/routes/notes.js
@@ -1,16 +1,18 @@
-import { createNote, deleteNote, getNote, listNotes, updateNote } from '../services/notes.js';
-import { noteSummary } from '../utils/format.js';
+import { archiveNote, createNote, deleteNote, getNote, listNotes, unarchiveNote, updateNote } from '../services/notes.js';
+import { noteDetail, noteSummary } from '../utils/format.js';
+
+const NOT_FOUND = { status: 404, body: { error: 'not found' } };
+const detail = (note) => (note ? { status: 200, body: noteDetail(note) } : NOT_FOUND);
 
 export const notesRoutes = {
-  'GET /notes': (req) => ({ status: 200, body: listNotes(req.user.id).map(noteSummary) }),
-  'GET /notes/:id': (req) => {
-    const note = getNote(req.user.id, req.params.id);
-    return note ? { status: 200, body: note } : { status: 404, body: { error: 'not found' } };
-  },
-  'POST /notes': (req) => ({ status: 201, body: createNote(req.user.id, req.body) }),
-  'PATCH /notes/:id': (req) => {
-    const note = updateNote(req.user.id, req.params.id, req.body ?? {});
-    return note ? { status: 200, body: note } : { status: 404, body: { error: 'not found' } };
-  },
-  'DELETE /notes/:id': (req) => (deleteNote(req.user.id, req.params.id) ? { status: 204 } : { status: 404, body: { error: 'not found' } }),
+  'GET /notes': (req) => ({
+    status: 200,
+    body: listNotes(req.user.id, { archived: req.query?.archived === 'true' }).map(noteSummary),
+  }),
+  'GET /notes/:id': (req) => detail(getNote(req.user.id, req.params.id)),
+  'POST /notes': (req) => ({ status: 201, body: noteDetail(createNote(req.user.id, req.body)) }),
+  'PATCH /notes/:id': (req) => detail(updateNote(req.user.id, req.params.id, req.body ?? {})),
+  'DELETE /notes/:id': (req) => (deleteNote(req.user.id, req.params.id) ? { status: 204 } : NOT_FOUND),
+  'POST /notes/:id/archive': (req) => detail(archiveNote(req.user.id, req.params.id)),
+  'POST /notes/:id/unarchive': (req) => detail(unarchiveNote(req.user.id, req.params.id)),
 };
diff --git a/src/services/notes.js b/src/services/notes.js
index 653af57..147678b 100644
--- a/src/services/notes.js
+++ b/src/services/notes.js
@@ -4,10 +4,10 @@ import { requireString, optionalTags } from '../utils/validate.js';
 import { invalidate } from './cache.js';
 import { record } from './audit.js';
 
-// Notes for one owner, newest first.
-export function listNotes(ownerId) {
+// Notes for one owner, newest first. Archived notes are only listed on request.
+export function listNotes(ownerId, { archived = false } = {}) {
   return all('notes')
-    .filter((n) => n.ownerId === ownerId)
+    .filter((n) => n.ownerId === ownerId && (n.archived === true) === archived)
     .sort((a, b) => b.createdAt - a.createdAt);
 }
 
@@ -23,6 +23,7 @@ export function createNote(ownerId, input) {
     title: requireString(input, 'title', { max: 120 }),
     body: requireString(input, 'body', { max: 10000 }),
     tags: optionalTags(input),
+    archived: false,
     createdAt: Date.now(),
   };
   insert('notes', note);
@@ -42,6 +43,17 @@ export function updateNote(ownerId, id, input) {
   return update('notes', id, patch);
 }
 
+function setArchived(ownerId, id, archived) {
+  if (!getNote(ownerId, id)) return null;
+  const note = update('notes', id, { archived });
+  invalidate(`notes:${ownerId}`);
+  record(ownerId, archived ? 'note.archive' : 'note.unarchive', id);
+  return note;
+}
+
+export const archiveNote = (ownerId, id) => setArchived(ownerId, id, true);
+export const unarchiveNote = (ownerId, id) => setArchived(ownerId, id, false);
+
 export function deleteNote(ownerId, id) {
   if (!getNote(ownerId, id)) return false;
   invalidate(`notes:${ownerId}`);
diff --git a/src/services/tags.js b/src/services/tags.js
index a5a9ea2..cb61d31 100644
--- a/src/services/tags.js
+++ b/src/services/tags.js
@@ -6,7 +6,7 @@ export function tagCounts(ownerId) {
   return cached(`notes:${ownerId}:tags`, () => {
     const counts = {};
     for (const note of all('notes')) {
-      if (note.ownerId !== ownerId) continue;
+      if (note.ownerId !== ownerId || note.archived === true) continue;
       for (const tag of note.tags) counts[tag] = (counts[tag] ?? 0) + 1;
     }
     return counts;
diff --git a/src/utils/format.js b/src/utils/format.js
index 24a3a09..dc6f329 100644
--- a/src/utils/format.js
+++ b/src/utils/format.js
@@ -20,9 +20,15 @@ export function noteSummary(note) {
     preview: truncate(note.body, 40),
     created: formatDate(note.createdAt),
     tags: [...note.tags].sort(),
+    archived: note.archived === true,
   };
 }
 
+// Full note as returned by the detail routes.
+export function noteDetail(note) {
+  return { ...note, archived: note.archived === true };
+}
+
 export function userSummary(user) {
   return { id: user.id, name: user.name, role: user.role };
 }
diff --git a/tests/api.test.js b/tests/api.test.js
index 32d499e..d9f1c98 100644
--- a/tests/api.test.js
+++ b/tests/api.test.js
@@ -2,9 +2,13 @@ import { test, beforeEach } from 'node:test';
 import assert from 'node:assert/strict';
 import { seed } from '../src/db/seed.js';
 import { handle } from '../src/server.js';
+import { invalidate } from '../src/services/cache.js';
 import { sign } from '../src/middleware/auth.js';
 
-beforeEach(seed);
+beforeEach(() => {
+  seed();
+  invalidate('notes:');
+});
 const as = (userId, req) => handle({ headers: { authorization: `Bearer ${sign(userId)}` }, ...req });
 
 test('health is public', () => {
@@ -37,3 +41,74 @@ test('search ranks title matches first', () => {
   const res = as('u1', { method: 'GET', path: '/search', query: { q: 'list' } });
   assert.deepEqual(res.body.map((n) => n.title), ['Book list']);
 });
+
+const post = (user, path) => as(user, { method: 'POST', path });
+const get = (user, path, query) => as(user, { method: 'GET', path, query });
+
+test('archive and unarchive return the updated note', () => {
+  const a = post('u1', '/notes/n2/archive');
+  assert.equal(a.status, 200);
+  assert.equal(a.body.id, 'n2');
+  assert.equal(a.body.archived, true);
+  const u = post('u1', '/notes/n2/unarchive');
+  assert.equal(u.status, 200);
+  assert.equal(u.body.archived, false);
+});
+
+test("archiving someone else's or a missing note is a 404", () => {
+  for (const action of ['archive', 'unarchive']) {
+    assert.equal(post('u1', `/notes/n1/${action}`).status, 404);
+    assert.equal(post('u1', `/notes/nope/${action}`).status, 404);
+  }
+  assert.equal(get('u2', '/notes/n1').body.archived, false);
+});
+
+test('archive routes need a token', () => {
+  assert.equal(handle({ method: 'POST', path: '/notes/n2/archive', headers: {} }).status, 401);
+});
+
+test('archived notes leave the list but show with archived=true', () => {
+  post('u1', '/notes/n2/archive');
+  const list = get('u1', '/notes');
+  assert.equal(list.body.length, 7);
+  assert.ok(!list.body.some((n) => n.id === 'n2'));
+  const archived = get('u1', '/notes', { archived: 'true' });
+  assert.deepEqual(archived.body.map((n) => n.id), ['n2']);
+  assert.equal(archived.body[0].archived, true);
+  post('u1', '/notes/n2/unarchive');
+  assert.equal(get('u1', '/notes').body.length, 8);
+  assert.equal(get('u1', '/notes', { archived: 'true' }).body.length, 0);
+});
+
+test('archived notes are hidden from search', () => {
+  const id = get('u1', '/search', { q: 'list' }).body[0].id;
+  post('u1', `/notes/${id}/archive`);
+  assert.deepEqual(get('u1', '/search', { q: 'list' }).body, []);
+});
+
+test('archived notes are not counted in tag counts', () => {
+  const before = get('u1', '/tags/counts').body;
+  const tag = get('u1', '/notes/n2').body.tags[0];
+  post('u1', '/notes/n2/archive');
+  assert.equal(get('u1', '/tags/counts').body[tag], before[tag] - 1);
+  post('u1', '/notes/n2/unarchive');
+  assert.deepEqual(get('u1', '/tags/counts').body, before);
+});
+
+test('GET /notes/:id still returns an archived note', () => {
+  post('u1', '/notes/n2/archive');
+  const res = get('u1', '/notes/n2');
+  assert.equal(res.status, 200);
+  assert.equal(res.body.archived, true);
+});
+
+test('every returned note includes a boolean archived flag', () => {
+  const created = as('u1', { method: 'POST', path: '/notes', body: { title: 'T', body: 'B' } });
+  const patched = as('u1', { method: 'PATCH', path: '/notes/n2', body: { title: 'X' } });
+  const one = get('u1', '/notes/n3');
+  const list = get('u1', '/notes');
+  const search = get('u1', '/search', { q: 'list' });
+  for (const n of [created.body, patched.body, one.body, ...list.body, ...search.body]) {
+    assert.equal(typeof n.archived, 'boolean');
+  }
+});