A temporary chat that keeps the model it was started on

The new-chat screen keeps its preselections in the query string, and the
three ways off it each rebuilt the URL with only their own key: the
Temporary button went to /chat?temporary=1, the model picker to
/chat?model=<id>, and /temp to /chat?temporary=1. So each undid the other,
and a temporary chat could only be started on the default model. The
folder from "New chat here" and the agent kind were dropped the same way.

chat_index now builds both URLs from one set of carried values and changes
only its own key; /temp keeps location.search when run on /chat.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -16,6 +16,15 @@ for 1.0.0 have something to be assembled from.
 
 ## Unreleased
 
+## 1.9.1
+
+- **A temporary chat can be started on any model.** On the new-chat screen,
+  turning on Temporary switched the model back to the default, and choosing a
+  model switched Temporary off, so a temporary chat could only ever be started
+  on the default model. The Temporary button, the model menu and `/temp` now
+  keep each other's choice, and also keep the folder a chat was started in
+  ("New chat here") and whether it is an agent chat.
+
 ## 1.9.0
 
 The model menu says which model is loaded, and a new chat now matches the

src/lembas/__init__.py

@@ -1,3 +1,3 @@
 """LLeMbas - a Middle-earth themed web UI for OpenAI-compatible LLM endpoints."""
 
-__version__ = "1.9.0"
+__version__ = "1.9.1"

src/lembas/api/pages.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+from urllib.parse import urlencode
 from zoneinfo import available_timezones
 
 from fastapi import APIRouter, HTTPException, Request, Response, status
@@ -727,6 +728,24 @@ async def chat_index(
     if preselected is None and context["models"]:
         preselected = context["models"][0]
 
+    # Every preselection lives in the URL, so every link that changes one of
+    # them has to carry the rest. The temporary toggle used to link to a bare
+    # `/chat?temporary=1` and the model picker to a bare `/chat?model=`, so
+    # each undid the other: temporary chats could only ever be started on the
+    # default model. The model goes last in the picker's URL because ui.js
+    # appends the chosen id to it.
+    carried = {
+        "model": model if model and preselected and preselected.model_id == model else "",
+        "temporary": "1" if temporary else "",
+        "kind": kind if kind in KINDS and kind != KIND_CHAT else "",
+        "folder": starting_folder.id if starting_folder is not None else "",
+    }
+
+    def new_chat_url(**changes: str) -> str:
+        query = urlencode({k: v for k, v in {**carried, **changes}.items() if v})
+        return f"/chat?{query}" if query else "/chat"
+
+    without_model = new_chat_url(model="")
     return render(
         request,
         "chat/index.html",
@@ -749,6 +768,8 @@ async def chat_index(
                 else chat_service.DEFAULT_EFFORTS
             ),
             "starting_temporary": temporary,
+            "temporary_toggle_url": new_chat_url(temporary="" if temporary else "1"),
+            "model_navigate_url": without_model + ("&" if "?" in without_model else "?") + "model=",
             "starting_kind": kind if kind in KINDS else KIND_CHAT,
             "starting_folder": starting_folder,
             "suggestions": suggestions_service.visible(db),

src/lembas/web/static/js/commands.js

@@ -222,7 +222,16 @@
     {
       name: "temp",
       summary: "Start a temporary chat, gone after a day",
-      run: function () { window.location = "/chat?temporary=1"; }
+      run: function () {
+        /* On the new-chat screen the model, folder and kind already chosen are
+           in the query string. Add the flag to them rather than starting over,
+           or the chat is made on the default model. */
+        var query = new URLSearchParams(
+          window.location.pathname === "/chat" ? window.location.search : ""
+        );
+        query.set("temporary", "1");
+        window.location = "/chat?" + query.toString();
+      }
     },
     {
       name: "stop",

src/lembas/web/templates/chat/_model_picker.html

@@ -91,7 +91,9 @@
   </form>
   {% else %}
   {# No chat yet: selecting navigates so the whole composer re-renders with the
-     right vision warning and the right hidden model_id. #}
+     right vision warning and the right hidden model_id. The URL carries the
-  <span hidden data-picker-navigate="/chat?model="></span>
+     other preselections -- temporary, folder, kind -- and ends in `model=`,
+     which ui.js completes. #}
+  <span hidden data-picker-navigate="{{ model_navigate_url }}"></span>
   {% endif %}
 </div>

src/lembas/web/templates/chat/index.html

@@ -65,11 +65,12 @@
       <div class="topbar__actions">
         {#
           A link, not a script: the flag lives in the URL, so it survives a
-          reload and can be bookmarked.
+          reload and can be bookmarked. The URL is built in `chat_index` so it
+          keeps the chosen model, folder and kind.
         #}
         {% if not chat and can.get("chat.create") %}
         <a class="btn btn--icon {{ 'is-active' if starting_temporary }}"
-           href="{{ '/chat' if starting_temporary else '/chat?temporary=1' }}"
+           href="{{ temporary_toggle_url }}"
            aria-label="{{ t('Temporary chat') }}"
            title="{% if starting_temporary %}Starting a temporary chat. Click to go back to a normal one.{% else %}Start a temporary chat: not listed in the sidebar, and removed after a day.{% endif %}">
           {{ icon("clock") }}

tests/test_commands_js.py

@@ -58,3 +58,12 @@ def test_send_from_anywhere_never_means_stop():
     stops."""
     window = SOURCE[SOURCE.index('event.code === "Enter"') :][:600]
     assert 'composerAction === "send"' in window
+
+
+def test_temp_keeps_what_the_new_chat_screen_already_chose():
+    """`/temp` went to a bare `/chat?temporary=1`, so on a new-chat screen with
+    a model picked it quietly swapped back to the default model."""
+    window = SOURCE[SOURCE.index('name: "temp"') :][:600]
+    assert 'window.location = "/chat?temporary=1"' not in window
+    assert "window.location.search" in window
+    assert 'query.set("temporary", "1")' in window

tests/test_temporary_chat.py

@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+import html
+import re
 from datetime import UTC, datetime, timedelta
 
 from fastapi.testclient import TestClient
@@ -100,6 +102,59 @@ def test_the_new_chat_screen_carries_the_flag(client: TestClient, db, registered
     assert 'name="temporary"' in client.get("/chat?temporary=1").text
 
 
+def _temporary_link(page: str) -> str:
+    match = re.search(r'href="([^"]*)"\s+aria-label="Temporary chat"', page)
+    assert match, "no temporary toggle on the page"
+    return html.unescape(match.group(1))
+
+
+def _picker_url(page: str) -> str:
+    match = re.search(r'data-picker-navigate="([^"]*)"', page)
+    assert match, "no navigating model picker on the page"
+    return html.unescape(match.group(1))
+
+
+def test_the_temporary_toggle_keeps_the_chosen_model(client: TestClient, db, registered):
+    """Temporary chats could only be started on the default model: the toggle
+    linked to a bare `/chat?temporary=1`, so the model picked a moment before
+    was dropped."""
+    connection = _connection(db)
+    db.add(Model(connection_id=connection.id, model_id="other-model"))
+    db.commit()
+
+    on = _temporary_link(client.get("/chat?model=other-model").text)
+    assert "model=other-model" in on and "temporary=1" in on
+    assert 'name="model_id" value="other-model"' in client.get(on).text
+
+    off = _temporary_link(client.get(on).text)
+    assert "model=other-model" in off and "temporary" not in off
+
+
+def test_choosing_a_model_keeps_the_temporary_flag(client: TestClient, db, registered):
+    """The other half: the picker navigated to a bare `/chat?model=`, so
+    picking a model after the toggle quietly made the chat an ordinary one."""
+    connection = _connection(db)
+    db.add(Model(connection_id=connection.id, model_id="other-model"))
+    db.commit()
+
+    url = _picker_url(client.get("/chat?temporary=1").text)
+    assert url.endswith("model=")
+    page = client.get(url + "other-model").text
+    assert 'name="temporary"' in page
+    assert 'name="model_id" value="other-model"' in page
+    assert _picker_url(client.get("/chat").text) == "/chat?model="
+
+
+def test_both_links_keep_the_folder(client: TestClient, db, registered):
+    _connection(db)
+    client.post("/api/folders", data={"name": "Quests"})
+    folder = db.scalar(select(Folder))
+
+    page = client.get(f"/chat?folder={folder.id}").text
+    assert f"folder={folder.id}" in _temporary_link(page)
+    assert f"folder={folder.id}" in _picker_url(page)
+
+
 def test_starting_a_temporary_chat_sets_the_flag(client: TestClient, db, registered):
     _connection(db)
     client.post("/api/chats/start", data={"content": "hello", "temporary": "true"})