refactor(webui): keep sidebar index out of session manager

nanobot/session/manager.py

@@ -31,8 +31,6 @@ _TOOL_CALL_ECHO_RE = re.compile(r'^\s*(?:generate_image|message)\([^)]*\)\s*$')
 _SESSION_PREVIEW_MAX_CHARS = 120
 _SESSION_LIST_PREVIEW_MAX_RECORDS = 200
 _SESSION_LIST_PREVIEW_MAX_CHARS = 1_000_000
-_SESSION_LIST_INDEX_VERSION = 1
-_SESSION_LIST_INDEX_FILENAME = ".session_index.json"
 _FORK_VOLATILE_METADATA_KEYS = {
     "goal_state",
     "pending_user_turn",
@@ -99,29 +97,6 @@ def _metadata_title(metadata: Any) -> str:
     return strip_think(title)
 
 
-def _session_list_preview_from_messages(messages: list[dict[str, Any]]) -> str:
-    preview = ""
-    fallback_preview = ""
-    scanned_records = 0
-    scanned_chars = 0
-    for item in messages:
-        scanned_records += 1
-        scanned_chars += len(json.dumps(item, ensure_ascii=False)) + 1
-        if (
-            scanned_records > _SESSION_LIST_PREVIEW_MAX_RECORDS
-            or scanned_chars > _SESSION_LIST_PREVIEW_MAX_CHARS
-        ):
-            break
-        text = _message_preview_text(item)
-        if not text:
-            continue
-        if item.get("role") == "user":
-            return text
-        if not fallback_preview and item.get("role") == "assistant":
-            fallback_preview = text
-    return preview or fallback_preview
-
-
 @dataclass
 class Session:
     """A conversation session."""
@@ -439,162 +414,6 @@ class SessionManager:
         """Legacy global session path (~/.nanobot/sessions/)."""
         return self.legacy_sessions_dir / f"{self.safe_key(key)}.jsonl"
 
-    def _session_index_path(self) -> Path:
-        return self.sessions_dir / _SESSION_LIST_INDEX_FILENAME
-
-    @staticmethod
-    def _session_file_signature(path: Path) -> dict[str, int]:
-        stat = path.stat()
-        return {"mtime_ns": stat.st_mtime_ns, "size": stat.st_size}
-
-    def _indexed_row_for_session(self, session: Session, path: Path) -> dict[str, Any]:
-        signature = self._session_file_signature(path)
-        return {
-            "key": session.key,
-            "created_at": session.created_at.isoformat(),
-            "updated_at": session.updated_at.isoformat(),
-            "title": _metadata_title(session.metadata),
-            "preview": _session_list_preview_from_messages(session.messages),
-            "file": path.name,
-            "mtime_ns": signature["mtime_ns"],
-            "size": signature["size"],
-        }
-
-    def _public_session_index_row(self, row: dict[str, Any]) -> dict[str, Any]:
-        return {
-            "key": row.get("key"),
-            "created_at": row.get("created_at"),
-            "updated_at": row.get("updated_at"),
-            "title": row.get("title", ""),
-            "preview": row.get("preview", ""),
-            "path": str(self.sessions_dir / str(row.get("file", ""))),
-        }
-
-    def _read_session_index_rows_unchecked(self) -> list[dict[str, Any]] | None:
-        path = self._session_index_path()
-        if not path.is_file():
-            return None
-        try:
-            data = json.loads(path.read_text(encoding="utf-8"))
-        except (OSError, json.JSONDecodeError):
-            return None
-        if not isinstance(data, dict) or data.get("version") != _SESSION_LIST_INDEX_VERSION:
-            return None
-        rows = data.get("sessions")
-        if not isinstance(rows, list) or not all(isinstance(row, dict) for row in rows):
-            return None
-        return rows
-
-    def _write_session_index_rows(self, rows: list[dict[str, Any]]) -> None:
-        path = self._session_index_path()
-        tmp_path = path.with_suffix(".json.tmp")
-        data = {"version": _SESSION_LIST_INDEX_VERSION, "sessions": rows}
-        try:
-            tmp_path.write_text(json.dumps(data, ensure_ascii=False) + "\n", encoding="utf-8")
-            os.replace(tmp_path, path)
-        except BaseException:
-            tmp_path.unlink(missing_ok=True)
-            raise
-
-    def _update_session_index(self, row: dict[str, Any]) -> None:
-        try:
-            rows = self._read_session_index_rows_unchecked() or []
-            rows = [existing for existing in rows if existing.get("file") != row.get("file")]
-            rows.append(row)
-            self._write_session_index_rows(rows)
-        except Exception as e:
-            logger.debug("Failed to update session list index: {}", e)
-
-    def _remove_session_index_row(self, file_name: str) -> None:
-        try:
-            rows = self._read_session_index_rows_unchecked()
-            if not rows:
-                return
-            kept = [row for row in rows if row.get("file") != file_name]
-            if len(kept) == len(rows):
-                return
-            self._write_session_index_rows(kept)
-        except Exception as e:
-            logger.debug("Failed to remove session from list index: {}", e)
-
-    def _read_valid_session_index(self) -> list[dict[str, Any]] | None:
-        rows = self._read_session_index_rows_unchecked()
-        if rows is None:
-            return None
-        paths = sorted(self.sessions_dir.glob("*.jsonl"))
-        by_file = {row.get("file"): row for row in rows if isinstance(row.get("file"), str)}
-        if set(by_file) != {path.name for path in paths}:
-            return None
-        public_rows: list[dict[str, Any]] = []
-        for path in paths:
-            row = by_file.get(path.name)
-            if row is None:
-                return None
-            if not all(isinstance(row.get(key), str) for key in ("key", "created_at", "updated_at")):
-                return None
-            if not isinstance(row.get("title", ""), str) or not isinstance(row.get("preview", ""), str):
-                return None
-            try:
-                signature = self._session_file_signature(path)
-            except OSError:
-                return None
-            if row.get("mtime_ns") != signature["mtime_ns"] or row.get("size") != signature["size"]:
-                return None
-            public_rows.append(self._public_session_index_row(row))
-        return public_rows
-
-    def _session_index_row_from_file(self, path: Path) -> dict[str, Any] | None:
-        fallback_key = path.stem.replace("_", ":", 1)
-        try:
-            with open(path, encoding="utf-8") as f:
-                first_line = f.readline().strip()
-                if not first_line:
-                    return None
-                data = json.loads(first_line)
-                if data.get("_type") != "metadata":
-                    return None
-                preview = ""
-                fallback_preview = ""
-                scanned_records = 0
-                scanned_chars = 0
-                for line in f:
-                    if not line.strip():
-                        continue
-                    scanned_records += 1
-                    scanned_chars += len(line)
-                    if (
-                        scanned_records > _SESSION_LIST_PREVIEW_MAX_RECORDS
-                        or scanned_chars > _SESSION_LIST_PREVIEW_MAX_CHARS
-                    ):
-                        break
-                    item = json.loads(line)
-                    if item.get("_type") == "metadata":
-                        continue
-                    text = _message_preview_text(item)
-                    if not text:
-                        continue
-                    if item.get("role") == "user":
-                        preview = text
-                        break
-                    if not fallback_preview and item.get("role") == "assistant":
-                        fallback_preview = text
-                signature = self._session_file_signature(path)
-                return {
-                    "key": data.get("key") or fallback_key,
-                    "created_at": data.get("created_at"),
-                    "updated_at": data.get("updated_at"),
-                    "title": _metadata_title(data.get("metadata", {})),
-                    "preview": preview or fallback_preview,
-                    "file": path.name,
-                    "mtime_ns": signature["mtime_ns"],
-                    "size": signature["size"],
-                }
-        except Exception:
-            repaired = self._repair(fallback_key)
-            if repaired is None:
-                return None
-            return self._indexed_row_for_session(repaired, path)
-
     def get_or_create(self, key: str) -> Session:
         """
         Get an existing session or create a new one.
@@ -781,7 +600,6 @@ class SessionManager:
             raise
 
         self._cache[session.key] = session
-        self._update_session_index(self._indexed_row_for_session(session, path))
 
     def flush_all(self) -> int:
         """Re-save every cached session with fsync for durable shutdown.
@@ -814,7 +632,6 @@ class SessionManager:
             return False
         try:
             path.unlink()
-            self._remove_session_index_row(path.name)
             return True
         except OSError as e:
             logger.warning("Failed to delete session file {}: {}", path, e)
@@ -926,16 +743,75 @@ class SessionManager:
         Returns:
             List of session info dicts.
         """
-        sessions = self._read_valid_session_index()
-        if sessions is None:
-            indexed_rows = [
-                row
-                for path in self.sessions_dir.glob("*.jsonl")
-                if (row := self._session_index_row_from_file(path)) is not None
-            ]
+        sessions = []
+
+        for path in self.sessions_dir.glob("*.jsonl"):
+            fallback_key = path.stem.replace("_", ":", 1)
             try:
-                self._write_session_index_rows(indexed_rows)
-            except Exception as e:
-                logger.debug("Failed to write session list index: {}", e)
-            sessions = [self._public_session_index_row(row) for row in indexed_rows]
+                # Read the metadata line and a small preview for session lists.
+                with open(path, encoding="utf-8") as f:
+                    first_line = f.readline().strip()
+                    if first_line:
+                        data = json.loads(first_line)
+                        if data.get("_type") == "metadata":
+                            key = data.get("key") or path.stem.replace("_", ":", 1)
+                            metadata = data.get("metadata", {})
+                            title = _metadata_title(metadata)
+                            preview = ""
+                            fallback_preview = ""
+                            scanned_records = 0
+                            scanned_chars = 0
+                            for line in f:
+                                if not line.strip():
+                                    continue
+                                scanned_records += 1
+                                scanned_chars += len(line)
+                                if (
+                                    scanned_records > _SESSION_LIST_PREVIEW_MAX_RECORDS
+                                    or scanned_chars > _SESSION_LIST_PREVIEW_MAX_CHARS
+                                ):
+                                    break
+                                item = json.loads(line)
+                                if item.get("_type") == "metadata":
+                                    continue
+                                text = _message_preview_text(item)
+                                if not text:
+                                    continue
+                                if item.get("role") == "user":
+                                    preview = text
+                                    break
+                                if not fallback_preview and item.get("role") == "assistant":
+                                    fallback_preview = text
+                            preview = preview or fallback_preview
+                            sessions.append(
+                                {
+                                    "key": key,
+                                    "created_at": data.get("created_at"),
+                                    "updated_at": data.get("updated_at"),
+                                    "title": title,
+                                    "preview": preview,
+                                    "path": str(path),
+                                }
+                            )
+            except Exception:
+                repaired = self._repair(fallback_key)
+                if repaired is not None:
+                    sessions.append(
+                        {
+                            "key": repaired.key,
+                            "created_at": repaired.created_at.isoformat(),
+                            "updated_at": repaired.updated_at.isoformat(),
+                            "title": _metadata_title(repaired.metadata),
+                            "preview": next(
+                                (
+                                    text
+                                    for msg in repaired.messages
+                                    if (text := _message_preview_text(msg))
+                                ),
+                                "",
+                            ),
+                            "path": str(path),
+                        }
+                    )
+                continue
         return sorted(sessions, key=lambda x: x.get("updated_at", ""), reverse=True)

nanobot/webui/session_list_index.py

@@ -0,0 +1,219 @@
+"""Cache-only WebUI session list index.
+
+The core ``SessionManager`` owns durable conversation history. This module owns
+the WebUI sidebar optimization so core session writes stay independent from UI
+presentation caches.
+"""
+
+from __future__ import annotations
+
+import json
+import os
+from pathlib import Path
+from typing import Any
+
+from loguru import logger
+
+from nanobot.session.manager import (
+    _SESSION_LIST_PREVIEW_MAX_CHARS,
+    _SESSION_LIST_PREVIEW_MAX_RECORDS,
+    Session,
+    SessionManager,
+    _message_preview_text,
+    _metadata_title,
+)
+
+_INDEX_VERSION = 1
+_INDEX_FILENAME = ".webui_session_index.json"
+
+
+def list_webui_sessions(session_manager: SessionManager) -> list[dict[str, Any]]:
+    """Return session rows for the WebUI sidebar, backed by a rebuildable cache."""
+    rows, changed = _reconcile_index(session_manager)
+    if changed:
+        try:
+            _write_index_rows(session_manager.sessions_dir, rows)
+        except Exception as e:
+            logger.debug("Failed to write WebUI session list index: {}", e)
+    sessions = [_public_row(session_manager.sessions_dir, row) for row in rows]
+    return sorted(sessions, key=lambda row: row.get("updated_at", ""), reverse=True)
+
+
+def _reconcile_index(session_manager: SessionManager) -> tuple[list[dict[str, Any]], bool]:
+    existing_rows = _read_index_rows(session_manager.sessions_dir)
+    existing_by_file = {
+        row.get("file"): row
+        for row in existing_rows or []
+        if isinstance(row.get("file"), str)
+    }
+    paths = sorted(session_manager.sessions_dir.glob("*.jsonl"))
+    rows: list[dict[str, Any]] = []
+    changed = existing_rows is None
+
+    for path in paths:
+        row = existing_by_file.get(path.name)
+        if row is not None and _indexed_row_matches_file(row, path):
+            rows.append(row)
+            continue
+
+        changed = True
+        scanned = _scan_session_row(session_manager, path)
+        if scanned is not None:
+            rows.append(scanned)
+
+    if set(existing_by_file) != {path.name for path in paths}:
+        changed = True
+    if existing_rows is not None and rows != existing_rows:
+        changed = True
+    return rows, changed
+
+
+def _index_path(sessions_dir: Path) -> Path:
+    return sessions_dir / _INDEX_FILENAME
+
+
+def _read_index_rows(sessions_dir: Path) -> list[dict[str, Any]] | None:
+    path = _index_path(sessions_dir)
+    if not path.is_file():
+        return None
+    try:
+        data = json.loads(path.read_text(encoding="utf-8"))
+    except (OSError, json.JSONDecodeError):
+        return None
+    if not isinstance(data, dict) or data.get("version") != _INDEX_VERSION:
+        return None
+    rows = data.get("sessions")
+    if not isinstance(rows, list) or not all(isinstance(row, dict) for row in rows):
+        return None
+    return rows
+
+
+def _write_index_rows(sessions_dir: Path, rows: list[dict[str, Any]]) -> None:
+    path = _index_path(sessions_dir)
+    tmp_path = path.with_suffix(".json.tmp")
+    data = {"version": _INDEX_VERSION, "sessions": rows}
+    try:
+        tmp_path.write_text(json.dumps(data, ensure_ascii=False) + "\n", encoding="utf-8")
+        os.replace(tmp_path, path)
+    except BaseException:
+        tmp_path.unlink(missing_ok=True)
+        raise
+
+
+def _file_signature(path: Path) -> dict[str, int]:
+    stat = path.stat()
+    return {"mtime_ns": stat.st_mtime_ns, "size": stat.st_size}
+
+
+def _indexed_row_matches_file(row: dict[str, Any], path: Path) -> bool:
+    if not all(isinstance(row.get(key), str) for key in ("key", "created_at", "updated_at")):
+        return False
+    if not isinstance(row.get("title", ""), str) or not isinstance(row.get("preview", ""), str):
+        return False
+    if row.get("file") != path.name:
+        return False
+    try:
+        signature = _file_signature(path)
+    except OSError:
+        return False
+    return row.get("mtime_ns") == signature["mtime_ns"] and row.get("size") == signature["size"]
+
+
+def _public_row(sessions_dir: Path, row: dict[str, Any]) -> dict[str, Any]:
+    return {
+        "key": row.get("key"),
+        "created_at": row.get("created_at"),
+        "updated_at": row.get("updated_at"),
+        "title": row.get("title", ""),
+        "preview": row.get("preview", ""),
+        "path": str(sessions_dir / str(row.get("file", ""))),
+    }
+
+
+def _preview_from_messages(messages: list[dict[str, Any]]) -> str:
+    fallback_preview = ""
+    scanned_records = 0
+    scanned_chars = 0
+    for item in messages:
+        scanned_records += 1
+        scanned_chars += len(json.dumps(item, ensure_ascii=False)) + 1
+        if (
+            scanned_records > _SESSION_LIST_PREVIEW_MAX_RECORDS
+            or scanned_chars > _SESSION_LIST_PREVIEW_MAX_CHARS
+        ):
+            break
+        text = _message_preview_text(item)
+        if not text:
+            continue
+        if item.get("role") == "user":
+            return text
+        if not fallback_preview and item.get("role") == "assistant":
+            fallback_preview = text
+    return fallback_preview
+
+
+def _indexed_row_for_session(session: Session, path: Path) -> dict[str, Any]:
+    signature = _file_signature(path)
+    return {
+        "key": session.key,
+        "created_at": session.created_at.isoformat(),
+        "updated_at": session.updated_at.isoformat(),
+        "title": _metadata_title(session.metadata),
+        "preview": _preview_from_messages(session.messages),
+        "file": path.name,
+        "mtime_ns": signature["mtime_ns"],
+        "size": signature["size"],
+    }
+
+
+def _scan_session_row(session_manager: SessionManager, path: Path) -> dict[str, Any] | None:
+    fallback_key = path.stem.replace("_", ":", 1)
+    try:
+        with open(path, encoding="utf-8") as f:
+            first_line = f.readline().strip()
+            if not first_line:
+                return None
+            data = json.loads(first_line)
+            if data.get("_type") != "metadata":
+                return None
+            preview = ""
+            fallback_preview = ""
+            scanned_records = 0
+            scanned_chars = 0
+            for line in f:
+                if not line.strip():
+                    continue
+                scanned_records += 1
+                scanned_chars += len(line)
+                if (
+                    scanned_records > _SESSION_LIST_PREVIEW_MAX_RECORDS
+                    or scanned_chars > _SESSION_LIST_PREVIEW_MAX_CHARS
+                ):
+                    break
+                item = json.loads(line)
+                if item.get("_type") == "metadata":
+                    continue
+                text = _message_preview_text(item)
+                if not text:
+                    continue
+                if item.get("role") == "user":
+                    preview = text
+                    break
+                if not fallback_preview and item.get("role") == "assistant":
+                    fallback_preview = text
+            signature = _file_signature(path)
+            return {
+                "key": data.get("key") or fallback_key,
+                "created_at": data.get("created_at"),
+                "updated_at": data.get("updated_at"),
+                "title": _metadata_title(data.get("metadata", {})),
+                "preview": preview or fallback_preview,
+                "file": path.name,
+                "mtime_ns": signature["mtime_ns"],
+                "size": signature["size"],
+            }
+    except Exception:
+        repaired = session_manager._repair(fallback_key)
+        if repaired is None:
+            return None
+        return _indexed_row_for_session(repaired, path)

nanobot/webui/ws_http.py

@@ -62,6 +62,7 @@ from nanobot.webui.http_utils import (
 )
 from nanobot.webui.media_gateway import WebUIMediaGateway
 from nanobot.webui.session_automations import session_automations_payload
+from nanobot.webui.session_list_index import list_webui_sessions
 from nanobot.webui.sidebar_state import (
     read_webui_sidebar_state,
     write_webui_sidebar_state,
@@ -323,7 +324,7 @@ class GatewayHTTPHandler:
             return _http_error(401, "Unauthorized")
         if self.session_manager is None:
             return _http_error(503, "session manager unavailable")
-        sessions = self.session_manager.list_sessions()
+        sessions = list_webui_sessions(self.session_manager)
         from nanobot.session.webui_turns import websocket_turn_wall_started_at
 
         cleaned = []

tests/agent/test_session_manager_history.py

@@ -96,48 +96,6 @@ def test_list_sessions_bounds_preview_scan(tmp_path):
     assert rows[0]["preview"] == "assistant trace 0"
 
 
-def test_list_sessions_reuses_valid_index_without_scanning_files(tmp_path, monkeypatch):
-    manager = SessionManager(tmp_path)
-    session = manager.get_or_create("websocket:indexed")
-    session.add_message("user", "indexed preview")
-    manager.save(session)
-
-    assert manager.list_sessions()[0]["preview"] == "indexed preview"
-
-    def fail_scan(path):
-        raise AssertionError(f"unexpected session file scan: {path}")
-
-    monkeypatch.setattr(manager, "_session_index_row_from_file", fail_scan)
-
-    rows = manager.list_sessions()
-
-    assert rows[0]["key"] == "websocket:indexed"
-    assert rows[0]["preview"] == "indexed preview"
-
-
-def test_list_sessions_index_updates_on_save_and_delete(tmp_path, monkeypatch):
-    manager = SessionManager(tmp_path)
-    session = manager.get_or_create("websocket:index-refresh")
-    session.add_message("user", "before")
-    manager.save(session)
-    session.messages.clear()
-    session.add_message("user", "after")
-    session.metadata["title"] = "fresh title"
-    manager.save(session)
-
-    def fail_scan(path):
-        raise AssertionError(f"unexpected session file scan: {path}")
-
-    monkeypatch.setattr(manager, "_session_index_row_from_file", fail_scan)
-
-    rows = manager.list_sessions()
-    assert rows[0]["title"] == "fresh title"
-    assert rows[0]["preview"] == "after"
-
-    assert manager.delete_session("websocket:index-refresh") is True
-    assert manager.list_sessions() == []
-
-
 # --- Original regression test (from PR 2075) ---
 
 def test_get_history_drops_orphan_tool_results_when_window_cuts_tool_calls():

tests/channels/test_websocket_channel.py

@@ -2618,15 +2618,16 @@ def test_parse_envelope_rejects_legacy_and_garbage() -> None:
     assert _parse_envelope('{"type":123}') is None
 
 
-def test_sessions_list_includes_active_run_started_at() -> None:
+def test_sessions_list_includes_active_run_started_at(monkeypatch) -> None:
     from websockets.datastructures import Headers
     from websockets.http11 import Request
 
     from nanobot.session import webui_turns as wth
+    from nanobot.webui import ws_http as ws_http_module
 
     bus = MagicMock()
     session_manager = MagicMock()
-    session_manager.list_sessions.return_value = [
+    sessions = [
         {
             "key": "websocket:chat-1",
             "created_at": "2026-05-19T10:00:00Z",
@@ -2641,6 +2642,7 @@ def test_sessions_list_includes_active_run_started_at() -> None:
             "updated_at": "2026-05-19T10:01:00Z",
         },
     ]
+    monkeypatch.setattr(ws_http_module, "list_webui_sessions", lambda _session_manager: sessions)
     channel = WebSocketChannel(
         {"enabled": True, "allowFrom": ["*"]},
         bus,

tests/webui/test_session_list_index.py

@@ -0,0 +1,75 @@
+from __future__ import annotations
+
+from pathlib import Path
+
+import nanobot.webui.session_list_index as session_list_index
+from nanobot.session.manager import SessionManager
+
+
+def test_webui_session_list_reuses_valid_index_without_scanning_files(
+    tmp_path: Path,
+    monkeypatch,
+) -> None:
+    manager = SessionManager(tmp_path)
+    session = manager.get_or_create("websocket:indexed")
+    session.add_message("user", "indexed preview")
+    manager.save(session)
+
+    assert list_webui_sessions(manager)[0]["preview"] == "indexed preview"
+
+    def fail_scan(session_manager: SessionManager, path: Path) -> None:
+        raise AssertionError(f"unexpected session file scan: {path}")
+
+    monkeypatch.setattr(session_list_index, "_scan_session_row", fail_scan)
+
+    rows = list_webui_sessions(manager)
+
+    assert rows[0]["key"] == "websocket:indexed"
+    assert rows[0]["preview"] == "indexed preview"
+
+
+def test_webui_session_list_rescans_only_changed_file(tmp_path: Path, monkeypatch) -> None:
+    manager = SessionManager(tmp_path)
+    first = manager.get_or_create("websocket:first")
+    first.add_message("user", "first")
+    manager.save(first)
+    second = manager.get_or_create("websocket:second")
+    second.add_message("user", "second before")
+    manager.save(second)
+
+    assert {row["preview"] for row in list_webui_sessions(manager)} == {"first", "second before"}
+
+    second.messages.clear()
+    second.add_message("user", "second after")
+    manager.save(second)
+
+    original_scan = session_list_index._scan_session_row
+    scanned: list[str] = []
+
+    def record_scan(session_manager: SessionManager, path: Path) -> dict | None:
+        scanned.append(path.name)
+        return original_scan(session_manager, path)
+
+    monkeypatch.setattr(session_list_index, "_scan_session_row", record_scan)
+
+    rows = list_webui_sessions(manager)
+
+    assert scanned == [manager._get_session_path("websocket:second").name]
+    assert {row["preview"] for row in rows} == {"first", "second after"}
+
+
+def test_webui_session_list_drops_deleted_index_rows(tmp_path: Path) -> None:
+    manager = SessionManager(tmp_path)
+    session = manager.get_or_create("websocket:deleted")
+    session.add_message("user", "gone")
+    manager.save(session)
+
+    assert list_webui_sessions(manager)[0]["key"] == "websocket:deleted"
+
+    assert manager.delete_session("websocket:deleted") is True
+
+    assert list_webui_sessions(manager) == []
+
+
+def list_webui_sessions(manager: SessionManager) -> list[dict]:
+    return session_list_index.list_webui_sessions(manager)