feat(cli): add interactive TUI chat

Add a Textual chat interface with threaded SSE streaming, slash commands, interrupt handling, and bare nexus dispatch. Package it behind the tui extra, document usage, and cover command routing, dependencies, and headless interaction with tests.

CLAUDE.md

@@ -50,25 +50,28 @@ uvicorn synapse.main:sio_app --host 127.0.0.1 --port 8000 --reload
 cd interface/web && npm run dev
 ```
 
-**Management CLI** (`ncp`) — start/stop services with PID tracking, plus terminal
-access to the same features as the web UI (all via the REST API on `:8000`):
+**Management CLI** (`nexus` / `ncp`) — start/stop services with PID tracking, plus
+terminal access to the same features as the web UI (REST API on `:8000`):
 ```bash
 ./management/nexus-cli.sh start   # starts backend + frontend
 ./management/nexus-cli.sh stop
 ./management/nexus-cli.sh start --backend|-b / --frontend|-f / --memory|-m
 
-# Feature commands (dispatch to nexusos_cli/nexus_api.py — httpx, no TUI):
-ncp chat "<message>"              # stream a reply (POST /chat/stream)
-ncp memory list|add <text>|rm <id>
-ncp playbook list|show <id>       # first playbook (*) is the active system prompt
-ncp history [query]               # recent conversations
+# Interactive TUI (Hermes/OpenClaw-style; needs pip install 'nexusos-ai[tui]'):
+nexus                             # bare command opens the Textual chat TUI
+nexus tui                         # same, explicit
+
+# Feature one-shots (dispatch to nexusos_cli/nexus_api.py — httpx):
+nexus chat send "<message>"       # stream a reply (POST /chat/stream)
+nexus memory list|add <text>|rm <id>
+nexus playbook list|show <id>     # first playbook (*) is the active system prompt
+nexus history [query]             # recent conversations
+nexus monitor                     # ASCII status dashboard (no prompt)
 ```
-The old curses TUIs (`nexus-chat.py`, `nexus-playbook.py`) were removed in favor of
-these API-backed subcommands. The CLI covers chat, memory, playbooks, and history;
-the web UI and control panel expose the remaining management features.
-The CLI itself lives in `nexusos_cli/` (that is what the wheel ships and what
-`nexus`/`ncp`/`nexusos` dispatch to); `management/` keeps the desktop-only
-pieces — the shell wrappers, the Tk control panel, and the XFCE panel wiring.
+The interactive TUI lives in `nexusos_cli/tui_app.py` (Textual, optional extra).
+One-shot subcommands and `nexus monitor` remain for scripts. The CLI package is
+`nexusos_cli/` (what the wheel ships); `management/` keeps desktop-only pieces —
+shell wrappers, Tk control panel, XFCE panel wiring.
 `management/controlpanel.py` (tkinter GUI, wired into the XFCE panel via
 `bin/panel/nexus-popup.py`) stays.
 

docs/CLI.md

@@ -37,11 +37,14 @@ and seed playbooks. Extras keep platform-sensitive dependencies optional:
 - `desktop`: desktop process support and Windows pywebview
 - `search`: DuckDuckGo web search for chat
 - `mail`: IMAP mail reading
+- `tui`: Textual interactive chat UI (`nexus` with no subcommand)
 - `all`: every optional capability at once
 
 ## Common commands
 
 ```text
+nexus                              Interactive chat TUI (needs nexusos-ai[tui])
+nexus tui                          Same as bare nexus
 nexus init                         Create writable state and seed playbooks
 nexus doctor [--fix] [--json]     Diagnose the install and provider
 nexus paths [--json]              Show package, state, and asset locations

nexusos_cli/cli.py

@@ -398,6 +398,24 @@ def cmd_monitor(args) -> int:
     )
 
 
+def cmd_tui(args) -> int:
+    """Interactive Hermes/OpenClaw-style chat TUI (requires nexusos-ai[tui])."""
+    if not sys.stdin.isatty() or not sys.stdout.isatty():
+        print(
+            "The TUI needs a terminal. Use: nexus chat send \"…\"\n"
+            "Or run `nexus` in an interactive shell.",
+            file=sys.stderr,
+        )
+        return 2
+    try:
+        from .tui_app import run_tui
+    except ImportError as exc:
+        print(str(exc), file=sys.stderr)
+        return 2
+    api = getattr(args, "api_url", None) or settings.api_url
+    return run_tui(api_url=api)
+
+
 def _target_flag(target: str | None):
     return {
         "memory": "--memory",
@@ -722,10 +740,20 @@ def _port(value: str) -> int:
 
 
 def build_parser() -> argparse.ArgumentParser:
-    parser = argparse.ArgumentParser(prog="nexus", description="NexusOS local AI runtime and API client")
+    parser = argparse.ArgumentParser(
+        prog="nexus",
+        description=(
+            "NexusOS local AI runtime and API client. "
+            "With no subcommand, opens the interactive TUI (needs nexusos-ai[tui])."
+        ),
+    )
     parser.add_argument("--version", action="version", version=f"NexusOS {settings.version}")
     parser.add_argument("--api-url", help="override the NexusOS backend URL for this command")
-    sub = parser.add_subparsers(dest="command", required=True)
+    # Bare `nexus` → TUI. Subcommands remain for scripts and one-shots.
+    sub = parser.add_subparsers(dest="command", required=False)
+
+    p = sub.add_parser("tui", help="interactive chat TUI (default when no subcommand)")
+    p.set_defaults(fn=cmd_tui)
 
     p = sub.add_parser("init", help="create user state and seed default playbooks"); _add_json(p); p.set_defaults(fn=cmd_init)
     p = sub.add_parser("paths", help="show resolved package and writable paths"); _add_json(p); p.set_defaults(fn=cmd_paths)
@@ -827,7 +855,12 @@ def _normalize_legacy_argv(argv) -> list[str]:
 
 def main(argv=None) -> int:
     parser = build_parser()
-    args = parser.parse_args(_normalize_legacy_argv(argv))
+    argv = _normalize_legacy_argv(argv)
+    args = parser.parse_args(argv)
+    if not getattr(args, "command", None):
+        # Bare `nexus` / `ncp` / `nexusos` → interactive TUI.
+        args.command = "tui"
+        args.fn = cmd_tui
     if args.command == "config":
         if args.action in ("get", "unset") and not args.key:
             parser.error(f"config {args.action} requires KEY")

nexusos_cli/tui_app.py

@@ -0,0 +1,426 @@
+"""Hermes/OpenClaw-style interactive TUI for NexusOS.
+
+Optional: needs the ``tui`` extra (Textual). Launched by a bare ``nexus`` when
+stdin/stdout are a TTY. Classic one-shots (``nexus chat send``, ``nexus monitor``,
+``nexus status``, …) stay on the argparse tree.
+"""
+from __future__ import annotations
+
+import json
+import threading
+import uuid
+from typing import Any
+
+import httpx
+
+from synapse.nexus_config import settings
+
+from . import nexus_api
+from .monitor import collect_snapshot
+
+# Between SSE chunks a silent backend must not pin the UI forever. Connect stays
+# short; the overall stream may run minutes.
+_STREAM_TIMEOUT = httpx.Timeout(None, connect=5.0, read=120.0, write=30.0, pool=5.0)
+
+
+def _require_textual():
+    try:
+        from textual.app import App
+        from textual.widgets import Footer, Header, Input, RichLog, Static
+    except ImportError as e:  # pragma: no cover - optional extra
+        raise ImportError(
+            "The interactive TUI needs the 'tui' extra — "
+            "pip install 'nexusos-ai[tui]' (or: pip install textual)."
+        ) from e
+    return App, Footer, Header, Input, RichLog, Static
+
+
+def _escape(text: str) -> str:
+    """Make model/user text safe for Rich markup widgets.
+
+    Rich's own escape is the only version that round-trips. Escaping every
+    backslash by hand looks equivalent but is not: Rich un-escapes ``\\[`` and
+    never collapses ``\\\\``, so doubling them puts the doubles on screen -
+    every Windows path and regex escape in a reply renders wrong.
+
+    Imported inside the function so the module still loads without the ``tui``
+    extra. Rich is not declared in pyproject: Textual depends on it, so it is
+    present whenever the TUI can run at all, and tests/test_packaging_deps.py
+    lists it in TRANSITIVE for that reason.
+    """
+    from rich.markup import escape
+
+    return escape(text)
+
+
+def format_user_line(message: str) -> str:
+    return f"[bold green]you>[/] {_escape(message)}"
+
+
+def format_assistant_line(text: str) -> str:
+    return f"[bold blue]nexus>[/] {_escape(text)}"
+
+
+def _status_line(snap: dict | None = None) -> str:
+    """Format a snapshot. Pass ``snap`` — do not omit it on the UI thread."""
+    if snap is None:
+        snap = collect_snapshot()
+    svcs = snap.get("services") or {}
+    api = snap.get("api") or {}
+    host = snap.get("host") or {}
+    parts = [f"NexusOS {snap.get('version', '')}"]
+    for key in ("backend", "memory", "provider"):
+        info = svcs.get(key) or {}
+        if key == "provider":
+            up = bool(info.get("reachable"))
+        else:
+            up = bool(info.get("running"))
+        parts.append(f"{key}={'UP' if up else 'DOWN'}")
+    if api.get("online"):
+        parts.append(f"tools={api.get('action_tool_policy') or '—'}")
+    cpu = host.get("cpu_pct")
+    if cpu is not None:
+        parts.append(f"cpu={cpu:.0f}%")
+    chains = snap.get("toolchains") or []
+    ready = [c["lang"] for c in chains if c.get("ready")]
+    if ready:
+        parts.append("run=" + ",".join(ready))
+    return " · ".join(parts)
+
+
+def _compact_status(snap: dict | None = None) -> str:
+    """One-line strip for the bar under the chat log."""
+    if snap is None:
+        snap = collect_snapshot()
+    host = snap.get("host") or {}
+    api = snap.get("api") or {}
+    recent = snap.get("recent_tools") or []
+    cpu = host.get("cpu_pct")
+    mem = host.get("mem_pct")
+    bits = []
+    if cpu is not None:
+        bits.append(f"cpu {cpu:.0f}%")
+    if mem is not None:
+        bits.append(f"mem {mem:.0f}%")
+    if api.get("online"):
+        bits.append(
+            f"memories={api.get('memories') if api.get('memories') is not None else '—'} "
+            f"chats={api.get('conversations') if api.get('conversations') is not None else '—'}"
+        )
+    else:
+        bits.append("api DOWN — nexus start")
+    if recent:
+        bits.append("recent " + ", ".join(recent[:4]))
+    return "  │  ".join(bits)
+
+
+class NexusTUI:
+    """Factory so Textual imports stay lazy until run()."""
+
+    @staticmethod
+    def build_app(*, api_url: str | None = None):
+        App, Footer, Header, Input, RichLog, Static = _require_textual()
+        base = (api_url or settings.api_url).rstrip("/")
+
+        class AppImpl(App):
+            CSS = """
+            Screen { layout: vertical; }
+            #status {
+                height: 1;
+                dock: top;
+                background: $boost;
+                color: $text;
+                padding: 0 1;
+            }
+            #strip {
+                height: 1;
+                background: $surface;
+                color: $text-muted;
+                padding: 0 1;
+            }
+            #log {
+                height: 1fr;
+                border: tall $accent;
+                padding: 0 1;
+            }
+            #live {
+                height: auto;
+                max-height: 8;
+                padding: 0 1;
+                color: $text;
+            }
+            #prompt { dock: bottom; }
+            """
+            BINDINGS = [
+                ("ctrl+c", "interrupt", "Interrupt"),
+                ("ctrl+d", "quit", "Quit"),
+            ]
+
+            def __init__(self):
+                super().__init__()
+                self.api_url = base
+                self.conversation_id: str | None = None
+                self.history: list[dict] = []
+                self._model: str | None = None
+                self._busy = False
+                self._stop_stream = threading.Event()
+                self._http_client: httpx.Client | None = None
+                self._status_lock = threading.Lock()
+                self._status_pending = False
+
+            def compose(self):
+                # Placeholders only — never collect_snapshot() on the UI thread.
+                yield Header(show_clock=True)
+                yield Static("NexusOS …", id="status")
+                yield RichLog(id="log", highlight=True, markup=True, wrap=True)
+                yield Static("", id="live")
+                yield Static("collecting status…", id="strip")
+                yield Input(
+                    placeholder="Message Nexus…  (/help for commands)",
+                    id="prompt",
+                )
+                yield Footer()
+
+            def on_mount(self) -> None:
+                self.title = "NexusOS"
+                self.sub_title = self.api_url
+                log = self.query_one("#log", RichLog)
+                log.write("[bold]NexusOS[/] interactive TUI")
+                log.write(
+                    "Type a message and Enter. "
+                    "Slash: /help /status /new /model /quit"
+                )
+                log.write(f"API: {_escape(self.api_url)}")
+                log.write("")
+                self._schedule_status_refresh()
+                self.set_interval(2.0, self._schedule_status_refresh)
+                self.query_one("#prompt", Input).focus()
+
+            def _schedule_status_refresh(self) -> None:
+                """Kick a worker; never call collect_snapshot on the event loop."""
+                with self._status_lock:
+                    if self._status_pending:
+                        return
+                    self._status_pending = True
+
+                def worker():
+                    try:
+                        snap = collect_snapshot()
+                        self._call_ui(self._apply_status, snap)
+                    except Exception:
+                        pass
+                    finally:
+                        with self._status_lock:
+                            self._status_pending = False
+
+                threading.Thread(target=worker, daemon=True).start()
+
+            def _apply_status(self, snap: dict) -> None:
+                self.query_one("#status", Static).update(_status_line(snap))
+                self.query_one("#strip", Static).update(_compact_status(snap))
+
+            def _call_ui(self, callback, *args) -> None:
+                """call_from_thread, but never after quit (avoids CancelledError
+                traceback garbling the restored shell)."""
+                if not self.is_running:
+                    return
+                try:
+                    self.call_from_thread(callback, *args)
+                except BaseException:
+                    # CancelledError is BaseException; also ignore post-exit races.
+                    pass
+
+            def action_quit(self) -> None:
+                self._stop_stream.set()
+                client = self._http_client
+                if client is not None:
+                    try:
+                        client.close()
+                    except Exception:
+                        pass
+                self.exit()
+
+            def action_interrupt(self) -> None:
+                if self._busy:
+                    self._stop_stream.set()
+                    client = self._http_client
+                    if client is not None:
+                        try:
+                            client.close()
+                        except Exception:
+                            pass
+                    self.query_one("#log", RichLog).write(
+                        "[yellow]▸ interrupt requested[/]"
+                    )
+                else:
+                    self.exit()
+
+            def on_input_submitted(self, event: Input.Submitted) -> None:
+                text = (event.value or "").strip()
+                event.input.value = ""
+                if not text:
+                    return
+                if text.startswith("/"):
+                    self._handle_slash(text)
+                    return
+                if self._busy:
+                    self.query_one("#log", RichLog).write(
+                        "[yellow]Still streaming — wait or Ctrl+C to interrupt[/]"
+                    )
+                    return
+                self._start_chat(text)
+
+            def _handle_slash(self, text: str) -> None:
+                log = self.query_one("#log", RichLog)
+                cmd, _, rest = text[1:].partition(" ")
+                cmd = cmd.lower().strip()
+                rest = rest.strip()
+                if cmd in ("q", "quit", "exit"):
+                    self.exit()
+                elif cmd in ("h", "help"):
+                    log.write(
+                        "[bold]/help[/]   this list\n"
+                        "[bold]/status[/] refresh service strip\n"
+                        "[bold]/new[/]    fresh conversation\n"
+                        "[bold]/model[/] \\[name]  pin model for next turns\n"
+                        "[bold]/quit[/]   leave the TUI\n"
+                        "One-shot: [dim]nexus chat send \"…\"[/]"
+                    )
+                elif cmd == "status":
+                    self._schedule_status_refresh()
+                    log.write("[dim]refreshing status…[/]")
+                elif cmd == "new":
+                    self.conversation_id = None
+                    self.history = []
+                    log.write("[bold cyan]— new conversation —[/]")
+                elif cmd == "model":
+                    if rest:
+                        self._model = rest
+                        log.write(f"[dim]model pinned:[/] {_escape(rest)}")
+                    else:
+                        log.write(
+                            f"[dim]model:[/] {_escape(self._model or '(auto)')}"
+                        )
+                else:
+                    log.write(
+                        f"[red]unknown command[/] /{_escape(cmd)} — try /help"
+                    )
+
+            def _start_chat(self, message: str) -> None:
+                log = self.query_one("#log", RichLog)
+                live = self.query_one("#live", Static)
+                log.write(format_user_line(message))
+                live.update("[bold blue]nexus>[/] [dim]…[/]")
+                self._busy = True
+                self._stop_stream.clear()
+                if not self.conversation_id:
+                    self.conversation_id = str(uuid.uuid4())
+                body: dict[str, Any] = {
+                    "message": message,
+                    "conversation_id": self.conversation_id,
+                    "history": list(self.history),
+                }
+                if self._model:
+                    body["model"] = self._model
+                self.history.append({"role": "user", "content": message})
+
+                def worker():
+                    reply_parts: list[str] = []
+                    client = httpx.Client(
+                        base_url=self.api_url, timeout=_STREAM_TIMEOUT
+                    )
+                    self._http_client = client
+                    try:
+                        with client.stream(
+                            "POST", "/chat/stream", json=body
+                        ) as resp:
+                            if resp.status_code >= 400:
+                                detail = resp.read().decode(
+                                    "utf-8", errors="replace"
+                                )[:300]
+                                self._call_ui(
+                                    live.update,
+                                    f"[red]error HTTP {resp.status_code}[/] "
+                                    f"{_escape(detail)}",
+                                )
+                                return
+                            for kind, payload in nexus_api.iter_chunks(
+                                resp.iter_lines()
+                            ):
+                                if self._stop_stream.is_set():
+                                    break
+                                if kind == "chunk":
+                                    reply_parts.append(payload)
+                                    preview = "".join(reply_parts)
+                                    if len(preview) > 4000:
+                                        preview = "…" + preview[-4000:]
+                                    self._call_ui(
+                                        live.update,
+                                        format_assistant_line(preview),
+                                    )
+                                elif kind == "tool_request":
+                                    self._call_ui(
+                                        log.write,
+                                        "[yellow]▸ tool approval needed — "
+                                        "Approve in the web UI, or set "
+                                        "action_tool_policy=allow[/]",
+                                    )
+                                elif kind == "error":
+                                    try:
+                                        detail = json.loads(payload).get(
+                                            "detail", payload
+                                        )
+                                    except Exception:
+                                        detail = payload
+                                    self._call_ui(
+                                        live.update,
+                                        f"[red]error:[/] {_escape(str(detail))}",
+                                    )
+                                elif kind == "done":
+                                    break
+                    except httpx.ConnectError:
+                        self._call_ui(
+                            live.update,
+                            f"[red]Backend not reachable at "
+                            f"{_escape(self.api_url)}. Start it: nexus start[/]",
+                        )
+                    except Exception as exc:
+                        self._call_ui(
+                            live.update,
+                            f"[red]{_escape(type(exc).__name__)}:[/] "
+                            f"{_escape(str(exc))}",
+                        )
+                    finally:
+                        self._http_client = None
+                        try:
+                            client.close()
+                        except Exception:
+                            pass
+                        text = "".join(reply_parts).strip()
+                        self._call_ui(self._finish_stream, text)
+
+                threading.Thread(target=worker, daemon=True).start()
+
+            def _finish_stream(self, text: str) -> None:
+                log = self.query_one("#log", RichLog)
+                live = self.query_one("#live", Static)
+                try:
+                    if text:
+                        log.write(format_assistant_line(text))
+                        self.history.append(
+                            {"role": "assistant", "content": text}
+                        )
+                finally:
+                    # Always clear busy — a MarkupError must not wedge the TUI.
+                    live.update("")
+                    self._busy = False
+                    self._schedule_status_refresh()
+
+        return AppImpl()
+
+
+def run_tui(*, api_url: str | None = None) -> int:
+    """Run the Textual app. Returns a process exit code."""
+    app = NexusTUI.build_app(api_url=api_url)
+    app.run()
+    return 0

pyproject.toml

@@ -42,6 +42,7 @@ mail = ["imap-tools>=1.7,<2"]
 # synapse/search.py imports this lazily behind a bare except, so without it
 # declared the chat web-search path silently returns nothing.
 search = ["duckduckgo-search>=6,<9"]
+tui = ["textual>=1.0,<3"]
 desktop = [
   "psutil>=5.9,<8",
   "pywebview>=5,<7; platform_system == 'Windows'",
@@ -64,6 +65,7 @@ all = [
   "faster-whisper>=1.1,<2",
   "imap-tools>=1.7,<2",
   "duckduckgo-search>=6,<9",
+  "textual>=1.0,<3",
   "pywebview>=5,<7; platform_system == 'Windows'",
 ]
 dev = [

tests/test_cli_packaging.py

@@ -31,8 +31,23 @@ def run_cli(tmp_path: Path, *args: str) -> subprocess.CompletedProcess[str]:
 def test_help_exposes_portable_command_tree(tmp_path):
     result = run_cli(tmp_path, "--help")
     assert result.returncode == 0, result.stderr
-    for command in ("init", "config", "provider", "doctor", "serve", "models", "chat", "monitor"):
+    for command in ("init", "config", "provider", "doctor", "serve", "models", "chat", "monitor", "tui"):
         assert command in result.stdout
+    assert "interactive TUI" in result.stdout or "TUI" in result.stdout
+
+
+def test_bare_nexus_defaults_to_tui_command():
+    """No subcommand → TUI entry (Hermes-style). Non-TTY exits 2 without launching."""
+    from unittest import mock
+
+    from nexusos_cli.cli import build_parser, cmd_tui
+
+    parser = build_parser()
+    args = parser.parse_args([])
+    assert args.command is None  # filled in by main()
+    with mock.patch("sys.stdin.isatty", return_value=False), \
+         mock.patch("sys.stdout.isatty", return_value=False):
+        assert cmd_tui(args) == 2
 
 
 def test_legacy_cli_spellings_remain_compatible():

tests/test_packaging_deps.py

@@ -29,7 +29,8 @@ DISTRIBUTION_OF = {
 }
 
 # Provided by another declared distribution rather than named directly.
-TRANSITIVE = {"starlette", "socketio", "engineio"}
+# rich: Textual depends on it, so the tui extra already pulls it in.
+TRANSITIVE = {"starlette", "socketio", "engineio", "rich"}
 
 # Modules that ship inside this repo.
 FIRST_PARTY = {"synapse", "nexusos_cli", "modules", "management", "bin", "tests"}

tests/test_tui.py

@@ -0,0 +1,85 @@
+"""TUI helpers and headless App.run_test coverage."""
+from __future__ import annotations
+
+import asyncio
+
+import pytest
+from rich.text import Text
+
+from nexusos_cli.tui_app import (
+    _compact_status,
+    _escape,
+    _status_line,
+    format_assistant_line,
+    format_user_line,
+)
+
+
+def test_status_line_mentions_services():
+    snap = {
+        "version": "1.0.0",
+        "services": {
+            "backend": {"running": True},
+            "memory": {"running": False},
+            "provider": {"reachable": True},
+        },
+        "api": {"online": True, "action_tool_policy": "ask"},
+        "host": {"cpu_pct": 10.0},
+        "toolchains": [{"lang": "python", "ready": True}],
+    }
+    line = _status_line(snap)
+    assert "backend=UP" in line
+    assert "memory=DOWN" in line
+    assert "provider=UP" in line
+    assert "tools=ask" in line
+    assert "run=python" in line
+
+
+def test_compact_status_handles_api_down():
+    snap = {
+        "host": {},
+        "api": {"online": False},
+        "recent_tools": [],
+    }
+    assert "api DOWN" in _compact_status(snap)
+
+
+def test_escape_preserves_code_brackets_in_display():
+    raw = "idx = arr[i] and rng = [a-z]+"
+    plain = Text.from_markup(format_assistant_line(raw)).plain
+    assert "arr[i]" in plain
+    assert "[a-z]+" in plain
+    # Unescaped markup would drop the bracket contents.
+    assert plain != "nexus> idx = arr and rng = +"
+
+
+def test_closing_tag_in_model_output_does_not_raise():
+    raw = "close with [/] please"
+    plain = Text.from_markup(format_assistant_line(raw)).plain
+    assert "[/]" in plain
+
+
+def test_user_line_escapes_markup():
+    plain = Text.from_markup(format_user_line("use [bold] please")).plain
+    assert "[bold]" in plain
+
+
+def test_finish_stream_markup_does_not_wedge_busy():
+    """A stray '[/]' used to raise before _busy=False and lock the TUI forever."""
+    pytest.importorskip("textual")
+    from nexusos_cli.tui_app import NexusTUI
+
+    app = NexusTUI.build_app(api_url="http://127.0.0.1:9")
+
+    async def _run():
+        async with app.run_test():
+            app._busy = True
+            app._finish_stream("see [/] and arr[i]")
+            assert app._busy is False
+            assert app.history[-1]["content"] == "see [/] and arr[i]"
+
+    asyncio.run(_run())
+
+
+def test_escape_round_trip_helper():
+    assert "[" in _escape("x[y]") or "\\[" in _escape("x[y]")