feat(webui): polish chat layout and titles

Align the WebUI sidebar and chat chrome with the updated design, and generate WebUI session titles asynchronously without blocking turns.

Co-authored-by: Cursor <cursoragent@cursor.com>

nanobot/utils/webui_titles.py

@@ -0,0 +1,138 @@
+"""Helpers for WebUI chat title generation."""
+
+from __future__ import annotations
+
+import re
+from typing import Any
+
+from loguru import logger
+
+from nanobot.providers.base import LLMProvider
+from nanobot.session.manager import Session, SessionManager
+from nanobot.utils.helpers import truncate_text
+
+WEBUI_SESSION_METADATA_KEY = "webui"
+WEBUI_TITLE_METADATA_KEY = "title"
+WEBUI_TITLE_USER_EDITED_METADATA_KEY = "title_user_edited"
+TITLE_MAX_CHARS = 60
+
+
+def mark_webui_session(session: Session, metadata: dict[str, Any]) -> bool:
+    """Persist a WebUI marker only when the inbound websocket frame opted in."""
+    if metadata.get(WEBUI_SESSION_METADATA_KEY) is not True:
+        return False
+    session.metadata[WEBUI_SESSION_METADATA_KEY] = True
+    return True
+
+
+def clean_generated_title(raw: str | None) -> str:
+    text = (raw or "").strip()
+    if not text:
+        return ""
+    text = re.sub(r"^\s*(title|标题)\s*[:：]\s*", "", text, flags=re.IGNORECASE)
+    text = text.strip().strip("\"'`“”‘’")
+    text = re.sub(r"\s+", " ", text).strip()
+    text = text.rstrip("。.!！?？,，;；:")
+    if len(text) > TITLE_MAX_CHARS:
+        text = text[: TITLE_MAX_CHARS - 1].rstrip() + "…"
+    return text
+
+
+def _title_inputs(session: Session) -> tuple[str, str]:
+    user_text = ""
+    assistant_text = ""
+    for message in session.messages:
+        role = message.get("role")
+        content = message.get("content")
+        if not isinstance(content, str) or not content.strip():
+            continue
+        if role == "user" and not user_text:
+            user_text = content.strip()
+        elif role == "assistant" and not assistant_text:
+            assistant_text = content.strip()
+        if user_text and assistant_text:
+            break
+    return user_text, assistant_text
+
+
+async def maybe_generate_webui_title(
+    *,
+    sessions: SessionManager,
+    session_key: str,
+    provider: LLMProvider,
+    model: str,
+) -> bool:
+    """Generate and persist a short title for WebUI-owned sessions only."""
+    session = sessions.get_or_create(session_key)
+    if session.metadata.get(WEBUI_SESSION_METADATA_KEY) is not True:
+        return False
+    if session.metadata.get(WEBUI_TITLE_USER_EDITED_METADATA_KEY) is True:
+        return False
+    current_title = session.metadata.get(WEBUI_TITLE_METADATA_KEY)
+    if isinstance(current_title, str) and current_title.strip():
+        return False
+
+    user_text, assistant_text = _title_inputs(session)
+    if not user_text:
+        return False
+
+    prompt = (
+        "Generate a concise title for this chat.\n"
+        "Rules:\n"
+        "- Use the same language as the user when practical.\n"
+        "- 3 to 8 words.\n"
+        "- No quotes.\n"
+        "- No punctuation at the end.\n"
+        "- Return only the title.\n\n"
+        f"User: {truncate_text(user_text, 1_000)}"
+    )
+    if assistant_text:
+        prompt += f"\nAssistant: {truncate_text(assistant_text, 1_000)}"
+
+    try:
+        response = await provider.chat_with_retry(
+            [
+                {
+                    "role": "system",
+                    "content": (
+                        "You write short, neutral chat titles. "
+                        "Return only the title text."
+                    ),
+                },
+                {"role": "user", "content": prompt},
+            ],
+            tools=None,
+            model=model,
+            max_tokens=32,
+            temperature=0.2,
+            retry_mode="standard",
+        )
+    except Exception:
+        logger.debug("Failed to generate webui session title for {}", session_key, exc_info=True)
+        return False
+
+    title = clean_generated_title(response.content)
+    if not title or title.lower().startswith("error"):
+        return False
+    session.metadata[WEBUI_TITLE_METADATA_KEY] = title
+    sessions.save(session)
+    return True
+
+
+async def maybe_generate_webui_title_after_turn(
+    *,
+    channel: str,
+    metadata: dict[str, Any],
+    sessions: SessionManager,
+    session_key: str,
+    provider: LLMProvider,
+    model: str,
+) -> bool:
+    if channel != "websocket" or metadata.get(WEBUI_SESSION_METADATA_KEY) is not True:
+        return False
+    return await maybe_generate_webui_title(
+        sessions=sessions,
+        session_key=session_key,
+        provider=provider,
+        model=model,
+    )