feat: add reusable session cloning endpoint

backend/routes/sessions.py

@@ -71,6 +71,22 @@ async def get_session(session_id: str):
         raise HTTPException(404, "Session not found")
     return s
 
+@router.post("/{session_id}/clone")
+async def clone_session(session_id: str):
+    s = db_service.get_session(session_id)
+    if not s:
+        raise HTTPException(404, "Session not found")
+    new_id = str(uuid.uuid4())
+    db_service.create_session(new_id, title=f"{s['title']} (Copy)", model=s["model"])
+    messages = db_service.get_messages_full(session_id)
+    for msg in messages:
+        db_service.save_message(
+            new_id,
+            msg["role"],
+            msg["content"],
+            msg["sources"]
+        )
+    return db_service.get_session(new_id)
 
 @router.patch("/{session_id}")
 async def update_session(session_id: str, body: SessionUpdate):

backend/tests/test_api.py

@@ -60,7 +60,28 @@ def test_delete_session():
     r2 = client.delete(f"/api/sessions/{sid}")
     assert r2.status_code == 200
 
-
+def test_clone_session():
+    r = client.post(
+        "/api/sessions/",
+        json={"title": "Original Chat", "model": "llama3"}
+    )
+    sid = r.json()["id"]
+    db.save_message(sid, "user", "Hello")
+    db.save_message(sid, "assistant", "Hi there")
+    clone = client.post(f"/api/sessions/{sid}/clone")
+    assert clone.status_code == 200
+    cloned = clone.json()
+    assert cloned["id"] != sid
+    assert cloned["title"] == "Original Chat (Copy)"
+    assert cloned["model"] == "llama3"
+    msgs = client.get(f"/api/sessions/{cloned['id']}/messages")
+    assert msgs.status_code == 200
+    assert msgs.json()["count"] == 2
+
+def test_clone_session_not_found():
+    r = client.post("/api/sessions/nonexistent/clone")
+    assert r.status_code == 404
+
 def test_get_messages_empty():
     r = client.post("/api/sessions/", json={"title": "Msg Test"})
     sid = r.json()["id"]