diff --git a/src/hqt/sessions/service.py b/src/hqt/sessions/service.py
index c11e6be..d8d4a4b 100644
--- a/src/hqt/sessions/service.py
+++ b/src/hqt/sessions/service.py
@@ -826,6 +826,37 @@ class SessionService:
             db.delete(sess)
             db.commit()
 
+    async def archive_session(self, session_id: int) -> None:
+        """Archive a session: kill its tmux window but keep the DB row.
+
+        A recoverable "remove from view" — the window/harness process is torn
+        down (freeing resources) but the row, ``harness_session_id``, and any
+        worktree are preserved so the session can be restored or referenced
+        later. No-op if the session does not exist.
+        """
+        with self.factory() as db:
+            sess = db.get(Session, session_id)
+            if sess is None:
+                return
+            if await self.tmux.window_exists(sess.tmux_session_name):
+                await self.tmux.kill(sess.tmux_session_name)
+            sess.archived = True
+            db.commit()
+
+    async def unarchive_session(self, session_id: int) -> None:
+        """Restore an archived session by clearing its archived flag.
+
+        The tmux window stays gone (the session reads as dead until resumed);
+        this only makes the row visible in the active list again. No-op if the
+        session does not exist.
+        """
+        with self.factory() as db:
+            sess = db.get(Session, session_id)
+            if sess is None:
+                return
+            sess.archived = False
+            db.commit()
+
     async def worktree_state_for(self, session_id: int) -> WorktreeState | None:
         """Return the WorktreeState for a session's worktree, or None.
 
diff --git a/tests/test_sessions.py b/tests/test_sessions.py
index bbf4902..5a5d271 100644
--- a/tests/test_sessions.py
+++ b/tests/test_sessions.py
@@ -2170,3 +2170,43 @@ async def test_list_sessions_archived_filter(service, db, tmux):
 
     archived = await service.list_sessions(project_id=1, archived=True)
     assert [i.session.id for i in archived] == [arch_id]
+
+
+@pytest.mark.asyncio
+async def test_archive_session_kills_window_and_keeps_row(service, db, tmux):
+    await service.create_session(project_id=1, harness_name="claude-code")
+    await service.archive_session(1)
+
+    tmux.kill.assert_called_once_with("hqt-1")
+    db.expire_all()
+    row = db.get(Session, 1)
+    assert row is not None
+    assert row.archived is True
+    # Excluded from the default (active) listing.
+    assert await service.list_sessions(project_id=1) == []
+
+
+@pytest.mark.asyncio
+async def test_archive_session_no_kill_when_window_missing(service, db, tmux):
+    await service.create_session(project_id=1, harness_name="claude-code")
+    tmux.window_exists = AsyncMock(return_value=False)
+    tmux.kill.reset_mock()
+
+    await service.archive_session(1)
+
+    tmux.kill.assert_not_called()
+    db.expire_all()
+    assert db.get(Session, 1).archived is True
+
+
+@pytest.mark.asyncio
+async def test_unarchive_session_restores_to_active_list(service, db, tmux):
+    await service.create_session(project_id=1, harness_name="claude-code")
+    await service.archive_session(1)
+
+    await service.unarchive_session(1)
+
+    db.expire_all()
+    assert db.get(Session, 1).archived is False
+    active = await service.list_sessions(project_id=1)
+    assert [i.session.id for i in active] == [1]