From 50270e13f7c6446c4b94a640158e753e74a21952 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jaroslav=20Bene=C5=A1?= <admin@ecoposta.sk>
Date: Tue, 4 Aug 2026 08:46:08 +0200
Subject: [PATCH] Names that fit the chat, and a way to change one

Two things about titles were wrong. Every chat spent a second completion on
its name, including an agent chat whose opening words are already a title --
somebody starting one states an objective, not a topic. An agent chat now
takes `fallback_title` from its first prompt and makes no request at all;
an ordinary chat, which opens with a question whose *answer* is what makes a
title worth asking for, is unchanged.

And renaming existed only as the `/title` slash command, which set the heading
and left the sidebar row showing the old name until the next reload -- a rename
that looks half-applied is one people do twice. There are pencil buttons on the
heading and on every sidebar row now, both PATCHing the route that was already
there, and `update_chat` answers a rename with the out-of-band pair the `done`
frame has always sent, so one response moves both. Only on a rename: sending it
for every PATCH would overwrite the heading from an unrelated save. `/title`
sets both spans itself, being a bare fetch rather than htmx.

The dialog is the `data-prompt` mechanism the folder work added, which is why
the heading keeps a button rather than becoming an inline field: it sits in a
flex row beside the badges and the connection chip, and swapping it for a text
box moves all of them.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 src/lembas/api/chats.py                       |  12 +
 src/lembas/services/generation.py             |   9 +-
 src/lembas/web/static/js/commands.js          |  13 +-
 src/lembas/web/templates/chat/index.html      |  17 ++
 .../web/templates/partials/_chat_link.html    |  11 +
 tests/test_chat_titles.py                     | 221 ++++++++++++++++++
 6 files changed, 279 insertions(+), 4 deletions(-)
 create mode 100644 tests/test_chat_titles.py

diff --git a/src/lembas/api/chats.py b/src/lembas/api/chats.py
index dad3f7e..1a29379 100644
--- a/src/lembas/api/chats.py
+++ b/src/lembas/api/chats.py
@@ -1463,12 +1463,14 @@ async def update_chat(request: Request, db: Db, user: RequiredUser, chat_id: str
     allowed = permissions.resolve(db, user)
     form = await request.form()
 
+    renamed = False
     if "title" in form:
         cleaned = str(form["title"]).strip()[:300]
         if cleaned:
             chat.title = cleaned
             # An explicit rename must not be overwritten by auto-titling later.
             chat.title_generated = True
+            renamed = True
 
     if "folder_id" in form:
         chat.folder_id = str(form["folder_id"]) or None
@@ -1576,6 +1578,16 @@ async def update_chat(request: Request, db: Db, user: RequiredUser, chat_id: str
             chat.params_json = {**(chat.params_json or {}), "reasoning_effort": seeded}
 
     db.commit()
+
+    if renamed:
+        # The two out-of-band spans the `done` frame already uses, so one
+        # response updates the heading *and* the sidebar row. Renaming used to
+        # be the `/title` command alone, which set the heading and left the
+        # sidebar showing the old name until the next reload -- a rename that
+        # looks half-applied is one people do twice.
+        return HTMLResponse(
+            templates.get_template("chat/_title_oob.html").render({"chat": chat})
+        )
     return Response(status_code=status.HTTP_204_NO_CONTENT)
 
 
diff --git a/src/lembas/services/generation.py b/src/lembas/services/generation.py
index 460a1de..e71da32 100644
--- a/src/lembas/services/generation.py
+++ b/src/lembas/services/generation.py
@@ -406,6 +406,13 @@ async def _run(generation: Generation) -> None:
             )
             question = _question_from(payload)
             needs_title = not chat.title_generated
+            # An agent chat is titled from its opening words and never costs a
+            # model call for it. That prompt is a good title already -- somebody
+            # starting one states an objective, not a topic -- while an ordinary
+            # chat opens with a question, whose answer is what makes a title
+            # worth asking for. Read here with the rest, because titling happens
+            # after this session has closed.
+            title_from_prompt = chat.kind == KIND_AGENT
             # Read here, with the rest, because titling happens after this
             # session has closed and must not open another one.
             title_prompt = prompts_service.resolve(db, "task.title")
@@ -714,7 +721,7 @@ async def _run(generation: Generation) -> None:
         # a chat title is never worth surfacing an error for.
         title = ""
         if needs_title and question:
-            if generation.error or endpoint is None:
+            if title_from_prompt or generation.error or endpoint is None:
                 title = chat_service.fallback_title(question)
             else:
                 with contextlib.suppress(Exception):
diff --git a/src/lembas/web/static/js/commands.js b/src/lembas/web/static/js/commands.js
index a2dde4e..f127dd3 100644
--- a/src/lembas/web/static/js/commands.js
+++ b/src/lembas/web/static/js/commands.js
@@ -115,9 +115,16 @@
         body.append("title", wanted);
         fetch("/api/chats/" + chat(), { method: "PATCH", body: body, credentials: "same-origin" })
           .then(function () {
-            var heading = el("#chat-title");
-            // textContent, never innerHTML: this is text somebody typed.
-            if (heading) heading.textContent = wanted;
+            /* Both places the title appears. The heading alone left the sidebar
+               row showing the old name until the next reload, which reads as a
+               rename that half worked -- and is the reason the route now hands
+               back the out-of-band pair for every other caller. This one is a
+               bare fetch rather than htmx, so it sets them itself.
+
+               textContent, never innerHTML: this is text somebody typed. */
+            [el("#chat-title"), el("#chat-link-label-" + chat())].forEach(function (node) {
+              if (node) node.textContent = wanted;
+            });
             note("Renamed.");
           });
       }
diff --git a/src/lembas/web/templates/chat/index.html b/src/lembas/web/templates/chat/index.html
index cd93e30..40ad48f 100644
--- a/src/lembas/web/templates/chat/index.html
+++ b/src/lembas/web/templates/chat/index.html
@@ -25,6 +25,23 @@
 
       <h1 class="topbar__title">
         <span id="chat-title">{{ chat.title if chat else "New chat" }}</span>
+        {#
+          Rename, where the name is. A themed dialog through `data-prompt`
+          rather than an inline field: the heading is in a flex row beside the
+          badges and the connection chip, and swapping it for a text box moves
+          all of them. The response is the same out-of-band pair the `done`
+          frame sends, so the sidebar row follows without a second request.
+        #}
+        {% if chat %}
+        <button class="btn btn--icon btn--sm topbar__rename" type="button"
+                hx-patch="/api/chats/{{ chat.id }}" hx-swap="none"
+                data-prompt="What should this chat be called?"
+                data-prompt-title="Rename chat" data-prompt-field="title"
+                data-prompt-value="{{ chat.title }}"
+                aria-label="Rename chat" title="Rename chat">
+          {{ icon("pencil", "icon--sm") }}
+        </button>
+        {% endif %}
         {# Beside the title because it describes the chat rather than acting on
            it. The way out of it is Keep, in the overflow menu. #}
         {% if chat and chat.temporary %}
diff --git a/src/lembas/web/templates/partials/_chat_link.html b/src/lembas/web/templates/partials/_chat_link.html
index fae2045..dbf6325 100644
--- a/src/lembas/web/templates/partials/_chat_link.html
+++ b/src/lembas/web/templates/partials/_chat_link.html
@@ -16,6 +16,17 @@
           {{ '' if chat_item.unread else 'hidden' }} title="New reply"></span>
   </a>
   <span class="nav-item__actions">
+    {# Works from any page carrying the sidebar, not only from inside the chat.
+       The response carries both out-of-band spans, so the heading follows if
+       this happens to be the open chat. #}
+    <button class="btn btn--icon btn--sm" type="button"
+            hx-patch="/api/chats/{{ chat_item.id }}" hx-swap="none"
+            data-prompt="What should this chat be called?"
+            data-prompt-title="Rename chat" data-prompt-field="title"
+            data-prompt-value="{{ chat_item.title }}"
+            aria-label="Rename chat" title="Rename chat">
+      {{ icon("pencil", "icon--sm") }}
+    </button>
     <button class="btn btn--icon btn--sm" type="button"
             hx-delete="/api/chats/{{ chat_item.id }}"
             hx-confirm="Delete “{{ chat_item.title }}”? This cannot be undone."
diff --git a/tests/test_chat_titles.py b/tests/test_chat_titles.py
new file mode 100644
index 0000000..ad58d41
--- /dev/null
+++ b/tests/test_chat_titles.py
@@ -0,0 +1,221 @@
+"""How a chat gets its name, and how it gets a different one."""
+
+from __future__ import annotations
+
+from fastapi.testclient import TestClient
+from sqlalchemy import select
+
+from lembas.db.models import KIND_AGENT, ROLE_ASSISTANT, Chat, Connection, Message, Model, User
+from lembas.services import chat as chat_service
+from lembas.services import generation as generation_service
+from lembas.services.crypto import encrypt
+
+
+def _add_connection(db) -> Connection:
+    connection = Connection(
+        name="Test", base_url="http://127.0.0.1:1", api_key_encrypted=encrypt("")
+    )
+    db.add(connection)
+    db.commit()
+    db.add(Model(connection_id=connection.id, model_id="test-model"))
+    db.commit()
+    return connection
+
+
+def _chat_awaiting_a_reply(db, user_id, *, kind="chat", question="Rebuild the search index"):
+    connection = db.scalar(select(Connection))
+    chat = Chat(
+        user_id=user_id, model_id="test-model", connection_id=connection.id, kind=kind
+    )
+    db.add(chat)
+    db.commit()
+    db.add(Message(chat_id=chat.id, role="user", content=question, complete=True))
+    db.commit()
+    assistant = Message(chat_id=chat.id, role=ROLE_ASSISTANT, content="", complete=False)
+    db.add(assistant)
+    db.commit()
+    return chat.id, assistant.id
+
+
+def _stub_stream(text: str):
+    async def stream_chat(_endpoint, _payload):
+        yield {"choices": [{"delta": {"content": text}}]}
+
+    return stream_chat
+
+
+# --- Where a title comes from ---------------------------------------------------
+async def test_an_agent_chat_is_named_from_its_first_prompt(db, user_id, monkeypatch):
+    """Somebody starting one states an objective, not a topic, so the opening
+    words are already a title. No second completion is spent on it."""
+    _add_connection(db)
+    chat_id, message_id = _chat_awaiting_a_reply(db, user_id, kind=KIND_AGENT)
+    monkeypatch.setattr(generation_service, "stream_chat", _stub_stream("Done."))
+
+    asked = []
+
+    async def _never(*args, **kwargs):
+        asked.append(args)
+        return "From the model"
+
+    monkeypatch.setattr(chat_service, "generate_title", _never)
+
+    generation = generation_service.Generation(chat_id=chat_id, message_id=message_id)
+    await generation_service._run(generation)
+
+    db.expire_all()
+    assert db.get(Chat, chat_id).title == "Rebuild the search index"
+    assert asked == [], "an agent chat must not spend a completion on its name"
+
+
+async def test_an_ordinary_chat_still_asks_a_model(db, user_id, monkeypatch):
+    """The opening of an ordinary chat is a question, and its answer is what
+    makes a title worth asking for."""
+    _add_connection(db)
+    chat_id, message_id = _chat_awaiting_a_reply(db, user_id)
+    monkeypatch.setattr(generation_service, "stream_chat", _stub_stream("Like so."))
+
+    async def _titled(*args, **kwargs):
+        return "Search indexing, explained"
+
+    monkeypatch.setattr(chat_service, "generate_title", _titled)
+
+    generation = generation_service.Generation(chat_id=chat_id, message_id=message_id)
+    await generation_service._run(generation)
+
+    db.expire_all()
+    assert db.get(Chat, chat_id).title == "Search indexing, explained"
+
+
+async def test_an_agent_title_is_trimmed_on_a_word_boundary(db, user_id, monkeypatch):
+    _add_connection(db)
+    long = (
+        "Rebuild the search index and then reindex every document in the "
+        "knowledge base before the deploy"
+    )
+    chat_id, message_id = _chat_awaiting_a_reply(db, user_id, kind=KIND_AGENT, question=long)
+    monkeypatch.setattr(generation_service, "stream_chat", _stub_stream("Done."))
+
+    generation = generation_service.Generation(chat_id=chat_id, message_id=message_id)
+    await generation_service._run(generation)
+
+    db.expire_all()
+    title = db.get(Chat, chat_id).title
+    assert title == chat_service.fallback_title(long)
+    assert len(title) <= chat_service.MAX_TITLE_LENGTH + 1
+    assert title.endswith("…")
+
+
+async def test_an_agent_chat_is_named_only_once(db, user_id, monkeypatch):
+    _add_connection(db)
+    chat_id, message_id = _chat_awaiting_a_reply(db, user_id, kind=KIND_AGENT)
+    monkeypatch.setattr(generation_service, "stream_chat", _stub_stream("Done."))
+
+    generation = generation_service.Generation(chat_id=chat_id, message_id=message_id)
+    await generation_service._run(generation)
+    db.expire_all()
+    chat = db.get(Chat, chat_id)
+    assert chat.title_generated is True
+
+
+# --- Renaming ---------------------------------------------------------------------
+def test_a_rename_answers_with_both_places_the_title_appears(
+    client: TestClient, db, registered, make_chat
+):
+    """One response, two out-of-band spans. The heading alone left the sidebar
+    row showing the old name until the next reload, which reads as a rename
+    that half worked."""
+    _add_connection(db)
+    chat_id = make_chat()
+
+    response = client.patch(f"/api/chats/{chat_id}", data={"title": "Orthanc"})
+    assert response.status_code == 200
+    assert 'id="chat-title"' in response.text
+    assert f'id="chat-link-label-{chat_id}"' in response.text
+    assert "Orthanc" in response.text
+    assert db.get(Chat, chat_id).title == "Orthanc"
+
+
+def test_a_rename_stops_the_chat_being_auto_titled(client: TestClient, db, registered, make_chat):
+    _add_connection(db)
+    chat_id = make_chat()
+    client.patch(f"/api/chats/{chat_id}", data={"title": "Orthanc"})
+    assert db.get(Chat, chat_id).title_generated is True
+
+
+def test_a_title_is_escaped_on_the_way_back(client: TestClient, db, registered, make_chat):
+    """It is text somebody typed, and it lands in two spans on a page that can
+    open a shell."""
+    _add_connection(db)
+    chat_id = make_chat()
+
+    response = client.patch(
+        f"/api/chats/{chat_id}", data={"title": "<img src=x onerror=alert(1)>"}
+    )
+    assert "<img src=x" not in response.text
+    assert "&lt;img" in response.text
+
+
+def test_a_blank_rename_changes_nothing_and_says_nothing(
+    client: TestClient, db, registered, make_chat
+):
+    """A chat with no name is one nobody can find in the sidebar."""
+    _add_connection(db)
+    chat_id = make_chat()
+    db.get(Chat, chat_id).title = "Orthanc"
+    db.commit()
+
+    response = client.patch(f"/api/chats/{chat_id}", data={"title": "   "})
+    assert response.status_code == 204
+    assert db.get(Chat, chat_id).title == "Orthanc"
+
+
+def test_a_patch_that_is_not_a_rename_still_answers_204(
+    client: TestClient, db, registered, make_chat
+):
+    """The out-of-band pair is only right when the title actually moved. Sending
+    it for every PATCH would overwrite the heading from an unrelated save."""
+    _add_connection(db)
+    chat_id = make_chat()
+    assert client.patch(f"/api/chats/{chat_id}", data={"agent_mode": "auto"}).status_code == 204
+
+
+def test_renaming_someone_elses_chat_is_a_404(client: TestClient, db, registered, make_chat):
+    _add_connection(db)
+    other = User(name="Sam", email="sam@shire.test", password_hash="x")
+    db.add(other)
+    db.commit()
+    chat = Chat(user_id=other.id, model_id="test-model", title="Theirs")
+    db.add(chat)
+    db.commit()
+
+    assert client.patch(f"/api/chats/{chat.id}", data={"title": "Mine"}).status_code == 404
+    assert db.get(Chat, chat.id).title == "Theirs"
+
+
+# --- Where the button is ------------------------------------------------------------
+def test_the_rename_button_is_on_the_heading_and_the_row(
+    client: TestClient, db, registered, make_chat
+):
+    _add_connection(db)
+    chat_id = make_chat()
+    page = client.get(f"/chat/{chat_id}").text
+
+    assert page.count(f'hx-patch="/api/chats/{chat_id}"') >= 2
+    assert 'data-prompt-field="title"' in page
+
+
+def test_the_rename_button_posts_at_a_route_that_serves_patch(
+    client: TestClient, db, registered, make_chat
+):
+    """A control wired to a method its route does not serve fails silently."""
+    _add_connection(db)
+    chat_id = make_chat()
+    assert client.post(f"/api/chats/{chat_id}", data={"title": "x"}).status_code == 405
+    assert client.patch(f"/api/chats/{chat_id}", data={"title": "x"}).status_code == 200
+
+
+def test_the_new_chat_screen_offers_no_rename(client: TestClient, db, registered):
+    """There is no row to rename until the first message is sent."""
+    _add_connection(db)
+    assert 'data-prompt-field="title"' not in client.get("/chat").text