diff --git a/src/routes/notes.js b/src/routes/notes.js
index 8248dc1..bd488bd 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 { createNote, deleteNote, getNote, listNotes, setArchived, updateNote } from '../services/notes.js';
+import { noteDetail, noteSummary } from '../utils/format.js';
+
+const notFound = { status: 404, body: { error: 'not found' } };
+const found = (note) => (note ? { status: 200, body: noteDetail(note) } : notFound);
 
 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: String(req.query?.archived) === 'true' }).map(noteSummary),
+  }),
+  'GET /notes/:id': (req) => found(getNote(req.user.id, req.params.id)),
+  'POST /notes': (req) => ({ status: 201, body: noteDetail(createNote(req.user.id, req.body)) }),
+  'POST /notes/:id/archive': (req) => found(setArchived(req.user.id, req.params.id, true)),
+  'POST /notes/:id/unarchive': (req) => found(setArchived(req.user.id, req.params.id, false)),
+  'PATCH /notes/:id': (req) => found(updateNote(req.user.id, req.params.id, req.body ?? {})),
+  'DELETE /notes/:id': (req) => (deleteNote(req.user.id, req.params.id) ? { status: 204 } : notFound),
 };
diff --git a/src/services/notes.js b/src/services/notes.js
index 653af57..bfddbba 100644
--- a/src/services/notes.js
+++ b/src/services/notes.js
@@ -4,10 +4,11 @@ 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 excluded unless
+// `archived` is true, in which case only archived notes are returned.
+export function listNotes(ownerId, { archived = false } = {}) {
   return all('notes')
-    .filter((n) => n.ownerId === ownerId)
+    .filter((n) => n.ownerId === ownerId && Boolean(n.archived) === archived)
     .sort((a, b) => b.createdAt - a.createdAt);
 }
 
@@ -23,6 +24,7 @@ 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 +44,13 @@ export function updateNote(ownerId, id, input) {
   return update('notes', id, patch);
 }
 
+export function setArchived(ownerId, id, archived) {
+  if (!getNote(ownerId, id)) return null;
+  invalidate(`notes:${ownerId}`);
+  record(ownerId, archived ? 'note.archive' : 'note.unarchive', id);
+  return update('notes', id, { archived });
+}
+
 export function deleteNote(ownerId, id) {
   if (!getNote(ownerId, id)) return false;
   invalidate(`notes:${ownerId}`);
diff --git a/src/services/tags.js b/src/services/tags.js
index a5a9ea2..9f96b8e 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) 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..409111f 100644
--- a/src/utils/format.js
+++ b/src/utils/format.js
@@ -20,9 +20,14 @@ export function noteSummary(note) {
     preview: truncate(note.body, 40),
     created: formatDate(note.createdAt),
     tags: [...note.tags].sort(),
+    archived: Boolean(note.archived),
   };
 }
 
+export function noteDetail(note) {
+  return { ...note, archived: Boolean(note.archived) };
+}
+
 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..9dfa88c 100644
--- a/tests/api.test.js
+++ b/tests/api.test.js
@@ -37,3 +37,50 @@ 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 archive = (u, id) => as(u, { method: 'POST', path: `/notes/${id}/archive` });
+
+test('notes include archived flag in lists and singly', () => {
+  const list = as('u1', { method: 'GET', path: '/notes' });
+  assert.ok(list.body.every((n) => n.archived === false));
+  assert.equal(as('u1', { method: 'GET', path: '/notes/n2' }).body.archived, false);
+  const created = as('u1', { method: 'POST', path: '/notes', body: { title: 'New', body: 'Text' } });
+  assert.equal(created.body.archived, false);
+});
+
+test('archive hides note from list, search and tag counts but not GET by id', () => {
+  assert.equal(as('u1', { method: 'GET', path: '/tags/counts' }).body.work, 4); // primes cache
+  const res = archive('u1', 'n2');
+  assert.equal(res.status, 200);
+  assert.equal(res.body.archived, true);
+  assert.equal(as('u1', { method: 'GET', path: '/notes' }).body.length, 7);
+  assert.equal(as('u1', { method: 'GET', path: '/tags/counts' }).body.work, 3);
+  assert.deepEqual(as('u1', { method: 'GET', path: '/search', query: { q: 'book' } }).body, []);
+  const one = as('u1', { method: 'GET', path: '/notes/n2' });
+  assert.equal(one.status, 200);
+  assert.equal(one.body.archived, true);
+});
+
+test('GET /notes?archived=true lists only archived notes', () => {
+  assert.deepEqual(as('u1', { method: 'GET', path: '/notes', query: { archived: 'true' } }).body, []);
+  archive('u1', 'n2');
+  const res = as('u1', { method: 'GET', path: '/notes', query: { archived: 'true' } });
+  assert.deepEqual(res.body.map((n) => n.id), ['n2']);
+  assert.equal(res.body[0].archived, true);
+});
+
+test('unarchive restores a note', () => {
+  archive('u1', 'n2');
+  const res = as('u1', { method: 'POST', path: '/notes/n2/unarchive' });
+  assert.equal(res.status, 200);
+  assert.equal(res.body.archived, false);
+  assert.equal(as('u1', { method: 'GET', path: '/notes' }).body.length, 8);
+  assert.equal(as('u1', { method: 'GET', path: '/tags/counts' }).body.work, 4);
+});
+
+test('archive and unarchive are 404 for notes that are not yours or missing', () => {
+  assert.equal(archive('u2', 'n2').status, 404);
+  assert.equal(as('u2', { method: 'POST', path: '/notes/n2/unarchive' }).status, 404);
+  assert.equal(archive('u1', 'nope').status, 404);
+  assert.equal(as('u1', { method: 'GET', path: '/notes/n2' }).body.archived, false);
+});