feat(tui): run bang commands through the gateway

nanobot/command/builtin.py

@@ -12,7 +12,7 @@ from dataclasses import dataclass
 from typing import TYPE_CHECKING, Any, Literal, cast
 
 from nanobot import __version__
-from nanobot.bus.events import OutboundMessage
+from nanobot.bus.events import INBOUND_META_USER_SHELL, OutboundMessage
 from nanobot.command.router import CommandContext, CommandRouter, normalize_command_text
 from nanobot.utils.helpers import build_status_content
 from nanobot.utils.restart import set_restart_notice_to_env
@@ -37,6 +37,8 @@ CommandLifecycle = Literal[
     "agent_turn_with_args",
 ]
 
+USER_SHELL_COMMAND = "/__shell"
+
 
 @dataclass(frozen=True)
 class BuiltinCommandSpec:
@@ -999,6 +1001,30 @@ async def cmd_help(ctx: CommandContext) -> OutboundMessage:
     )
 
 
+async def cmd_user_shell(ctx: CommandContext) -> OutboundMessage:
+    """Run a trusted local ``!command`` through nanobot's exec policy."""
+    metadata = dict(ctx.msg.metadata or {})
+    if (
+        ctx.msg.channel != "websocket"
+        or metadata.get("webui") is not True
+        or metadata.get(INBOUND_META_USER_SHELL) is not True
+    ):
+        return OutboundMessage(
+            channel=ctx.msg.channel,
+            chat_id=ctx.msg.chat_id,
+            content="Shell commands are only available from a trusted local client.",
+            metadata={**metadata, "render_as": "text"},
+        )
+    if not ctx.args.strip():
+        return OutboundMessage(
+            channel=ctx.msg.channel,
+            chat_id=ctx.msg.chat_id,
+            content="Type a command after `!`, for example `!pwd`.",
+            metadata={**metadata, "render_as": "text"},
+        )
+    return await ctx.loop.execute_user_shell_command(ctx)
+
+
 def build_help_text() -> str:
     """Build canonical help text shared across channels."""
     lines = ["🐈 nanobot commands:"]
@@ -1038,3 +1064,5 @@ def register_builtin_commands(router: CommandRouter) -> None:
     router.exact("/help", cmd_help)
     router.exact("/pairing", cmd_pairing)
     router.prefix("/pairing ", cmd_pairing)
+    router.exact(USER_SHELL_COMMAND, cmd_user_shell)
+    router.prefix(f"{USER_SHELL_COMMAND} ", cmd_user_shell)