merge

src/textual_webterm/_two_way_dict.py

@@ -0,0 +1,89 @@
+from __future__ import annotations
+
+import threading
+from typing import Generic, TypeVar
+
+Key = TypeVar("Key")
+Value = TypeVar("Value")
+
+
+class TwoWayDict(Generic[Key, Value]):
+    """
+    A two-way mapping offering O(1) access in both directions.
+
+    Wraps two dictionaries and uses them to provide efficient access to
+    both values (given keys) and keys (given values).
+    """
+
+    def __init__(self, initial: dict[Key, Value] | None = None) -> None:
+        initial_data = {} if initial is None else initial
+        self._forward: dict[Key, Value] = initial_data
+        self._reverse: dict[Value, Key] = {value: key for key, value in initial_data.items()}
+        self._lock = threading.RLock()
+
+    def __setitem__(self, key: Key, value: Value) -> None:
+        with self._lock:
+            # If reassigning the same key, remove old reverse mapping first
+            old_value = self._forward.get(key)
+            if old_value is not None and old_value != value:
+                del self._reverse[old_value]
+            # Enforce 1:1 mapping: value must not already map to a different key
+            existing_key = self._reverse.get(value)
+            if existing_key is not None and existing_key != key:
+                raise ValueError(f"Value {value!r} already mapped to key {existing_key!r}")
+            self._forward[key] = value
+            self._reverse[value] = key
+
+    def __delitem__(self, key: Key) -> None:
+        with self._lock:
+            value = self._forward[key]
+            self._forward.__delitem__(key)
+            self._reverse.__delitem__(value)
+
+    def __iter__(self):
+        with self._lock:
+            return iter(dict(self._forward))
+
+    def get(self, key: Key) -> Value | None:
+        """Given a key, efficiently lookup and return the associated value.
+
+        Args:
+            key: The key
+
+        Returns:
+            The value
+        """
+        with self._lock:
+            return self._forward.get(key)
+
+    def get_key(self, value: Value) -> Key | None:
+        """Given a value, efficiently lookup and return the associated key.
+
+        Args:
+            value: The value
+
+        Returns:
+            The key
+        """
+        with self._lock:
+            return self._reverse.get(value)
+
+    def contains_value(self, value: Value) -> bool:
+        """Check if `value` is a value within this TwoWayDict.
+
+        Args:
+            value: The value to check.
+
+        Returns:
+            True if the value is within the values of this dict.
+        """
+        with self._lock:
+            return value in self._reverse
+
+    def __len__(self):
+        with self._lock:
+            return len(self._forward)
+
+    def __contains__(self, item: Key) -> bool:
+        with self._lock:
+            return item in self._forward

src/textual_webterm/app_session.py

@@ -0,0 +1,330 @@
+from __future__ import annotations
+
+import asyncio
+import io
+import json
+import logging
+import os
+from asyncio import IncompleteReadError, StreamReader, StreamWriter
+from datetime import timedelta
+from enum import Enum, auto
+from time import monotonic
+from typing import TYPE_CHECKING
+
+import rich.repr
+from importlib_metadata import version
+
+from . import constants
+from .session import Session, SessionConnector
+
+if TYPE_CHECKING:
+    from asyncio.subprocess import Process
+    from pathlib import Path
+
+    from .types import Meta, SessionID
+
+log = logging.getLogger("textual-web")
+
+# Maximum payload size to prevent memory exhaustion (16MB)
+MAX_PAYLOAD_SIZE = 16 * 1024 * 1024
+
+
+class ProcessState(Enum):
+    """The state of a process."""
+
+    PENDING = auto()
+    RUNNING = auto()
+    CLOSING = auto()
+    CLOSED = auto()
+
+    def __repr__(self) -> str:
+        return self.name
+
+
+@rich.repr.auto(angular=True)
+class AppSession(Session):
+    """Runs a single app process."""
+
+    def __init__(
+        self,
+        working_directory: Path,
+        command: str,
+        session_id: SessionID,
+        devtools: bool = False,
+    ) -> None:
+        self.working_directory = working_directory
+        self.command = command
+        self.session_id = session_id
+        self.devtools = devtools
+        self.start_time: float | None = None
+        self.end_time: float | None = None
+        self._process: Process | None = None
+        self._task: asyncio.Task | None = None
+
+        super().__init__()
+        self._state = ProcessState.PENDING
+
+    @property
+    def process(self) -> Process:
+        """The asyncio (sub)process"""
+        assert self._process is not None
+        return self._process
+
+    @property
+    def stdin(self) -> StreamWriter:
+        """The processes stdin."""
+        assert self._process is not None
+        assert self._process.stdin is not None
+        return self._process.stdin
+
+    @property
+    def stdout(self) -> StreamReader:
+        """The process' stdout."""
+        assert self._process is not None
+        assert self._process.stdout is not None
+        return self._process.stdout
+
+    @property
+    def stderr(self) -> StreamReader:
+        """The process' stderr."""
+        assert self._process is not None
+        assert self._process.stderr is not None
+        return self._process.stderr
+
+    @property
+    def task(self) -> asyncio.Task:
+        """Session task."""
+        assert self._task is not None
+        return self._task
+
+    @property
+    def state(self) -> ProcessState:
+        """Current running state."""
+        return self._state
+
+    @state.setter
+    def state(self, state: ProcessState) -> None:
+        self._state = state
+        run_time = self.run_time
+        log.debug(
+            "%r state=%r run_time=%s",
+            self,
+            self.state,
+            "0" if run_time is None else timedelta(seconds=int(run_time)),
+        )
+
+    @property
+    def run_time(self) -> float | None:
+        """Time process was running, or `None` if it hasn't started."""
+        if self.end_time is not None:
+            assert self.start_time is not None
+            return self.end_time - self.start_time
+        elif self.start_time is not None:
+            return monotonic() - self.start_time
+        else:
+            return None
+
+    def is_running(self) -> bool:
+        """Check if the app session is still running."""
+        return self._state == ProcessState.RUNNING
+
+    def __rich_repr__(self) -> rich.repr.Result:
+        yield self.command
+        yield "id", self.session_id
+        if self._process is not None:
+            yield "returncode", self._process.returncode, None
+
+    async def open(self, width: int = 80, height: int = 24) -> None:
+        """Open the process."""
+        environment = dict(os.environ.copy())
+        environment["TEXTUAL_DRIVER"] = "textual.drivers.web_driver:WebDriver"
+        environment["TEXTUAL_FPS"] = "60"
+        environment["TEXTUAL_COLOR_SYSTEM"] = "truecolor"
+        environment["TERM_PROGRAM"] = "textual-web"
+        environment["TERM_PROGRAM_VERSION"] = version("textual-web")
+        environment["COLUMNS"] = str(width)
+        environment["ROWS"] = str(height)
+        if self.devtools:
+            environment["TEXTUAL"] = "debug,devtools"
+            environment["TEXTUAL_LOG"] = "textual.log"
+
+        # Use cwd parameter instead of os.chdir() for thread safety
+        self._process = await asyncio.create_subprocess_shell(
+            self.command,
+            stdin=asyncio.subprocess.PIPE,
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.PIPE,
+            env=environment,
+            cwd=str(self.working_directory),
+        )
+        await self.set_terminal_size(width, height)
+        log.debug("opened %r; %r", self.command, self._process)
+        self.start_time = monotonic()
+
+    async def start(self, connector: SessionConnector) -> asyncio.Task:
+        """Start a task to run the process."""
+        if self._task is not None:
+            raise RuntimeError("AppSession.start() called while already running")
+        self._connector = connector
+        self._task = asyncio.create_task(self.run())
+        return self._task
+
+    async def close(self) -> None:
+        """Close the process."""
+        self.state = ProcessState.CLOSING
+        await self.send_meta({"type": "quit"})
+
+    async def wait(self) -> None:
+        """Wait for the process to finish (call close first)."""
+        if self._task:
+            await self._task
+            self._task = None
+
+    async def set_terminal_size(self, width: int, height: int) -> None:
+        """Set the terminal size for the process.
+
+        Args:
+            width: Width in cells.
+            height: Height in cells.
+        """
+        await self.send_meta(
+            {
+                "type": "resize",
+                "width": width,
+                "height": height,
+            }
+        )
+
+    async def run(self) -> None:
+        """This loop reads stdout from the process and relays it through the websocket."""
+
+        self.state = ProcessState.RUNNING
+
+        META = b"M"
+        DATA = b"D"
+        BINARY_ENCODED = b"P"
+
+        stderr_data = io.BytesIO()
+
+        async def read_stderr() -> None:
+            """Task to read stderr."""
+            try:
+                while True:
+                    data = await self.stderr.read(1024 * 4)
+                    if not data:
+                        break
+                    stderr_data.write(data)
+            except asyncio.CancelledError:
+                pass
+
+        stderr_task = asyncio.create_task(read_stderr())
+        readexactly = self.stdout.readexactly
+        from_bytes = int.from_bytes
+
+        on_data = self._connector.on_data
+        on_meta = self._connector.on_meta
+        on_binary_encoded_message = self._connector.on_binary_encoded_message
+        try:
+            ready = False
+            for _ in range(10):
+                line = await self.stdout.readline()
+                if not line:
+                    break
+                if line == b"__GANGLION__\n":
+                    ready = True
+                    break
+            if ready:
+                while True:
+                    type_bytes = await readexactly(1)
+                    size_bytes = await readexactly(4)
+                    size = from_bytes(size_bytes, "big")
+                    if size > MAX_PAYLOAD_SIZE:
+                        log.error("Payload size %d exceeds limit %d", size, MAX_PAYLOAD_SIZE)
+                        break
+                    payload = await readexactly(size)
+                    if type_bytes == DATA:
+                        await on_data(payload)
+                    elif type_bytes == META:
+                        meta_data = json.loads(payload)
+                        meta_type = meta_data.get("type")
+                        if meta_type in {"exit", "blur", "focus"}:
+                            await self.send_meta({"type": meta_type})
+                        else:
+                            await on_meta(meta_data)
+                    elif type_bytes == BINARY_ENCODED:
+                        await on_binary_encoded_message(payload)
+
+        except IncompleteReadError:
+            # Incomplete read means that the stream was closed
+            pass
+        except asyncio.CancelledError:
+            pass
+        finally:
+            stderr_task.cancel()
+            await stderr_task
+
+        self.end_time = monotonic()
+        self.state = ProcessState.CLOSED
+
+        stderr_message = stderr_data.getvalue().decode("utf-8", errors="replace")
+        if (
+            self._process is not None
+            and self._process.returncode != 0
+            and constants.DEBUG
+            and stderr_message
+        ):
+            log.warning(stderr_message)
+
+        await self._connector.on_close()
+
+    @classmethod
+    def encode_packet(cls, packet_type: bytes, payload: bytes) -> bytes:
+        """Encode a packet.
+
+        Args:
+            packet_type: The packet type (b"D" for data or b"M" for meta)
+            payload: The payload.
+
+        Returns:
+            Data as bytes.
+        """
+        return b"%s%s%s" % (packet_type, len(payload).to_bytes(4, "big"), payload)
+
+    async def send_bytes(self, data: bytes) -> bool:
+        """Send bytes to process.
+
+        Args:
+            data: Data to send.
+
+        Returns:
+            True if the data was sent, otherwise False.
+        """
+        if self._process is None or self._process.stdin is None:
+            return False
+        stdin = self._process.stdin
+        try:
+            stdin.write(self.encode_packet(b"D", data))
+            await stdin.drain()
+        except (RuntimeError, ConnectionResetError, BrokenPipeError):
+            return False
+        return True
+
+    async def send_meta(self, data: Meta) -> bool:
+        """Send meta information to process.
+
+        Args:
+            data: Meta dict to send.
+
+        Returns:
+            True if the data was sent, otherwise False.
+        """
+        if self._process is None or self._process.stdin is None:
+            return False
+        stdin = self._process.stdin
+        data_bytes = json.dumps(data).encode("utf-8")
+        try:
+            stdin.write(self.encode_packet(b"M", data_bytes))
+            await stdin.drain()
+        except (RuntimeError, ConnectionResetError, BrokenPipeError):
+            return False
+        return True

src/textual_webterm/cli.py

@@ -0,0 +1,229 @@
+from __future__ import annotations
+
+import asyncio
+import importlib
+import importlib.util
+import logging
+import os
+import sys
+from pathlib import Path
+
+import click
+from importlib_metadata import version
+from rich.logging import RichHandler
+
+from . import constants
+from .local_server import LocalServer
+
+FORMAT = "%(message)s"
+logging.basicConfig(
+    level="DEBUG" if constants.DEBUG else "INFO",
+    format=FORMAT,
+    datefmt="[%X]",
+    handlers=[RichHandler(show_path=False)],
+)
+
+log = logging.getLogger("textual-webterm")
+
+
+def _is_file_path(path: str) -> bool:
+    """Check if path looks like a file path (vs module path)."""
+    return path.endswith(".py") or "/" in path or "\\" in path
+
+
+def parse_app_path(app_path: str) -> tuple[str, str]:
+    """Parse an app path like 'module.path:ClassName' or 'path/to/file.py:ClassName'.
+
+    Returns:
+        Tuple of (module_or_file, class_name)
+    """
+    if ":" not in app_path:
+        raise click.BadParameter(
+            f"Invalid app path '{app_path}'. Expected format: 'module.path:ClassName' or 'path/to/file.py:ClassName'"
+        )
+
+    module_part, class_name = app_path.rsplit(":", 1)
+    return module_part, class_name
+
+
+def load_app_class(app_path: str):
+    """Load a Textual App class from a module path.
+
+    Args:
+        app_path: Path like 'module.path:ClassName' or 'path/to/file.py:ClassName'
+
+    Returns:
+        The App class
+    """
+    module_part, class_name = parse_app_path(app_path)
+
+    # Check if it's a file path or module path
+    if _is_file_path(module_part):
+        # File path - load from file
+        file_path = Path(module_part).resolve()
+        if not file_path.exists():
+            raise click.BadParameter(f"File not found: {file_path}")
+
+        # Add parent directory to sys.path for imports
+        parent_dir = str(file_path.parent)
+        if parent_dir not in sys.path:
+            sys.path.insert(0, parent_dir)
+
+        # Import the module
+        module_name = file_path.stem
+        spec = importlib.util.spec_from_file_location(module_name, file_path)
+        if spec is None or spec.loader is None:
+            raise click.BadParameter(f"Could not load module from {file_path}")
+
+        module = importlib.util.module_from_spec(spec)
+        sys.modules[module_name] = module
+        spec.loader.exec_module(module)
+    else:
+        # Module path - import normally
+        try:
+            module = importlib.import_module(module_part)
+        except ImportError as e:
+            raise click.BadParameter(f"Could not import module '{module_part}': {e}") from e
+
+    # Get the class
+    if not hasattr(module, class_name):
+        raise click.BadParameter(f"Module '{module_part}' has no attribute '{class_name}'")
+
+    app_class = getattr(module, class_name)
+    return app_class
+
+
+@click.command()
+@click.version_option(version("textual-webterm"))
+@click.argument("command", required=False)
+@click.option("--port", "-p", type=int, help="Port for server.", default=8080)
+@click.option("--host", "-H", help="Host for server.", default="0.0.0.0")
+@click.option(
+    "--app",
+    "-a",
+    "app_path",
+    help="Load a Textual app from module:ClassName (e.g., 'myapp:MyApp' or 'path/to/app.py:MyApp')",
+)
+@click.option(
+    "--landing-manifest",
+    "-L",
+    "landing_manifest",
+    type=click.Path(exists=True, dir_okay=False, readable=True, path_type=Path),
+    help="YAML manifest describing landing page tiles (slug/name/command).",
+)
+@click.option(
+    "--compose-manifest",
+    "-C",
+    "compose_manifest",
+    type=click.Path(exists=True, dir_okay=False, readable=True, path_type=Path),
+    help='Docker compose YAML; services with label "webterm-command" become landing tiles.',
+)
+def app(
+    command: str | None,
+    port: int,
+    host: str,
+    app_path: str | None,
+    landing_manifest: Path | None,
+    compose_manifest: Path | None,
+) -> None:
+    """Serve a terminal or Textual app over HTTP/WebSocket.
+
+    COMMAND: Shell command to run in terminal (default: $SHELL)
+
+    Examples:
+
+    \b
+        textual-webterm                           # Serve default shell
+        textual-webterm htop                      # Serve htop in terminal
+        textual-webterm --app mymodule:MyApp      # Serve a Textual app from module
+        textual-webterm -a ./calculator.py:CalculatorApp  # Serve from file
+    """
+    VERSION = version("textual-webterm")
+    log.info(f"textual-webterm v{VERSION}")
+
+    if constants.DEBUG:
+        log.warning("DEBUG env var is set; logs may be verbose!")
+
+    from .config import default_config, load_compose_manifest, load_landing_yaml
+
+    _config = default_config()
+
+    landing_apps: list = []
+    if landing_manifest:
+        landing_apps = load_landing_yaml(landing_manifest)
+    elif compose_manifest:
+        landing_apps = load_compose_manifest(compose_manifest)
+
+    server = LocalServer(
+        "./",
+        _config,
+        host=host,
+        port=port,
+        landing_apps=landing_apps,
+    )
+    for app_entry in landing_apps:
+        server.add_terminal(app_entry.name, app_entry.command, slug=app_entry.slug)
+
+    if app_path:
+        # Load and run as Textual app from module:class
+        try:
+            app_class = load_app_class(app_path)
+        except click.BadParameter as e:
+            log.error(str(e))
+            sys.exit(1)
+
+        # Create a command that runs the app using python -m runpy for safety
+        module_part, class_name = parse_app_path(app_path)
+        if _is_file_path(module_part):
+            # File path - use absolute path and proper escaping
+            file_path = Path(module_part).resolve()
+            # Use runpy to safely run the file
+            escaped_path = str(file_path).replace("'", "'\"'\"'")
+            escaped_class = class_name.replace("'", "'\"'\"'")
+            run_command = f'python3 -c \'import sys; sys.path.insert(0, "{file_path.parent}"); exec(open("{escaped_path}").read()); {escaped_class}().run()\''
+        else:
+            # Module path - validate module and class names
+            if not module_part.replace(".", "").replace("_", "").isalnum():
+                log.error(f"Invalid module path: {module_part}")
+                sys.exit(1)
+            if not class_name.isidentifier():
+                log.error(f"Invalid class name: {class_name}")
+                sys.exit(1)
+            run_command = (
+                f'python3 -c "from {module_part} import {class_name}; {class_name}().run()"'
+            )
+
+        app_name = getattr(app_class, "TITLE", None) or class_name
+        server.add_app(app_name, run_command, "")
+        log.info(f"Serving Textual app: {app_path}")
+    elif command:
+        # Run command as terminal
+        server.add_terminal("Terminal", command, "")
+        log.info(f"Serving terminal: {command}")
+    elif not landing_apps:
+        # Run default shell
+        terminal_command = os.environ.get("SHELL", "/bin/sh")
+        server.add_terminal("Terminal", terminal_command, "")
+        log.info(f"Serving terminal: {terminal_command}")
+
+    def _run_async():
+        if constants.WINDOWS:
+            asyncio.run(server.run())
+        else:
+            try:
+                import uvloop
+            except ImportError:
+                asyncio.run(server.run())
+            else:
+                if sys.version_info >= (3, 11):
+                    with asyncio.Runner(loop_factory=uvloop.new_event_loop) as runner:
+                        runner.run(server.run())
+                else:
+                    uvloop.install()
+                    asyncio.run(server.run())
+
+    _run_async()
+
+
+if __name__ == "__main__":
+    app()

src/textual_webterm/config.py

@@ -0,0 +1,150 @@
+from os.path import expandvars
+from pathlib import Path
+from typing import Annotated
+
+try:
+    import tomllib as tomli  # py311+
+except ImportError:  # pragma: no cover
+    import tomli
+import yaml
+from pydantic import BaseModel, Field
+from pydantic.functional_validators import AfterValidator
+
+from .identity import generate
+from .slugify import slugify
+
+ExpandVarsStr = Annotated[str, AfterValidator(expandvars)]
+
+
+class App(BaseModel):
+    """Defines an application."""
+
+    name: str
+    slug: str = ""
+    path: ExpandVarsStr = "./"
+    color: str = ""
+    command: ExpandVarsStr = ""
+    terminal: bool = False
+
+
+class Config(BaseModel):
+    """Root configuration model."""
+
+    apps: list[App] = Field(default_factory=list)
+    landing: list[App] = Field(default_factory=list)
+
+
+def default_config() -> Config:
+    """Get a default empty configuration.
+
+    Returns:
+        Configuration object.
+    """
+    return Config()
+
+
+def load_config(config_path: Path) -> Config:
+    """Load config from a path.
+
+    Args:
+        config_path: Path to TOML configuration.
+
+    Returns:
+        Config object.
+    """
+    with Path(config_path).open("rb") as config_file:
+        config_data = tomli.load(config_file)
+
+    def make_app(name, data: dict[str, object], terminal: bool = False) -> App:
+        data["name"] = name
+        data["terminal"] = terminal
+        if terminal:
+            data["slug"] = generate().lower()
+        elif not data.get("slug", ""):
+            data["slug"] = slugify(name)
+
+        return App(**data)
+
+    apps = [make_app(name, app) for name, app in config_data.get("app", {}).items()]
+
+    apps += [
+        make_app(name, app, terminal=True) for name, app in config_data.get("terminal", {}).items()
+    ]
+
+    config = Config(apps=apps)
+
+    return config
+
+
+def load_landing_yaml(manifest_path: Path) -> list[App]:
+    """Load landing apps from YAML manifest.
+
+    Expected schema: list of {name, slug, command, color?, path?, terminal?}
+    """
+    with manifest_path.open("r", encoding="utf-8") as f:
+        data = yaml.safe_load(f) or []
+    apps: list[App] = []
+    for entry in data:
+        if not isinstance(entry, dict):
+            continue
+        name = entry.get("name")
+        command = entry.get("command")
+        if not name or not command:
+            continue
+        slug = entry.get("slug") or slugify(name)
+        apps.append(
+            App(
+                name=name,
+                slug=slug,
+                command=command,
+                path=entry.get("path", "./"),
+                color=entry.get("color", ""),
+                terminal=bool(entry.get("terminal", True)),
+            )
+        )
+    return apps
+
+
+def _extract_label(labels: object, key: str) -> str | None:
+    """Extract a label value from either dict or list[str] forms."""
+    if isinstance(labels, dict):
+        value = labels.get(key)
+        if isinstance(value, str):
+            return value
+        return None
+    if isinstance(labels, list):
+        for item in labels:
+            if not isinstance(item, str):
+                continue
+            if "=" in item:
+                k, v = item.split("=", 1)
+                if k == key:
+                    return v
+    return None
+
+
+def load_compose_manifest(manifest_path: Path) -> list[App]:
+    """Load landing apps from a docker-compose YAML file using label `webterm-command`."""
+    with manifest_path.open("r", encoding="utf-8") as f:
+        data = yaml.safe_load(f) or {}
+    services = data.get("services", {}) if isinstance(data, dict) else {}
+    apps: list[App] = []
+    for name, service in services.items():
+        if not isinstance(service, dict):
+            continue
+        labels = service.get("labels", {})
+        command = _extract_label(labels, "webterm-command")
+        if not command:
+            continue
+        slug = slugify(name)
+        apps.append(
+            App(
+                name=name,
+                slug=slug,
+                command=command,
+                path=service.get("working_dir", "./"),
+                color="",
+                terminal=True,
+            )
+        )
+    return apps

src/textual_webterm/constants.py

@@ -0,0 +1,51 @@
+"""
+Constants that we might want to expose via the public API.
+"""
+
+from __future__ import annotations
+
+import os
+import platform
+from typing import Final
+
+get_environ = os.environ.get
+
+WINDOWS: Final = platform.system() == "Windows"
+"""True if running on Windows."""
+
+
+def get_environ_bool(name: str) -> bool:
+    """Check an environment variable switch.
+
+    Args:
+        name: Name of environment variable.
+
+    Returns:
+        `True` if the env var is "1", otherwise `False`.
+    """
+    has_environ = get_environ(name) == "1"
+    return has_environ
+
+
+def get_environ_int(name: str, default: int) -> int:
+    """Retrieves an integer environment variable.
+
+    Args:
+        name: Name of environment variable.
+        default: The value to use if the value is not set, or set to something other
+            than a valid integer.
+
+    Returns:
+        The integer associated with the environment variable if it's set to a valid int
+            or the default value otherwise.
+    """
+    try:
+        return int(os.environ[name])
+    except KeyError:
+        return default
+    except ValueError:
+        return default
+
+
+DEBUG: Final = get_environ_bool("DEBUG")
+"""Enable debug mode."""

src/textual_webterm/exit_poller.py

@@ -0,0 +1,53 @@
+from __future__ import annotations
+
+import asyncio
+import logging
+from time import monotonic
+from typing import TYPE_CHECKING
+
+EXIT_POLL_RATE = 5
+
+log = logging.getLogger("textual-web")
+
+if TYPE_CHECKING:
+    from .local_server import LocalServer
+
+
+class ExitPoller:
+    """Monitors the client for an idle state, and exits."""
+
+    def __init__(self, client: LocalServer, idle_wait: int) -> None:
+        self.client = client
+        self.idle_wait = idle_wait
+        self._task: asyncio.Task | None = None
+        self._idle_start_time: float | None = None
+
+    def start(self) -> None:
+        """Start polling."""
+        self._task = asyncio.create_task(self.run())
+
+    def stop(self) -> None:
+        """Stop polling"""
+        if self._task is not None:
+            self._task.cancel()
+
+    async def run(self) -> None:
+        """Run the poller."""
+        if not self.idle_wait:
+            return
+        try:
+            while True:
+                await asyncio.sleep(EXIT_POLL_RATE)
+                is_idle = not self.client.session_manager.sessions
+                if is_idle:
+                    if self._idle_start_time is not None:
+                        if monotonic() - self._idle_start_time > self.idle_wait:
+                            log.info("Exiting due to --exit-on-idle")
+                            self.client.force_exit()
+                    else:
+                        self._idle_start_time = monotonic()
+                else:
+                    self._idle_start_time = None
+
+        except asyncio.CancelledError:
+            pass

src/textual_webterm/identity.py

@@ -0,0 +1,11 @@
+import os
+
+SEPARATOR = "-"
+IDENTITY_ALPHABET = "0123456789ABCDEFGHJKMNPQRSTUVWYZ"
+IDENTITY_SIZE = 12
+
+
+def generate(size: int = IDENTITY_SIZE) -> str:
+    """Generate a random identifier."""
+    alphabet = IDENTITY_ALPHABET
+    return "".join(alphabet[byte % 31] for byte in os.urandom(size))

src/textual_webterm/local_server.py

@@ -0,0 +1,621 @@
+"""Local server implementation for serving terminals over HTTP/WebSocket."""
+
+from __future__ import annotations
+
+import asyncio
+import contextlib
+import io
+import json
+import logging
+import signal
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+import aiohttp
+from aiohttp import WSMsgType, web
+from rich.ansi import AnsiDecoder
+from rich.console import Console
+
+from . import constants
+from .exit_poller import ExitPoller
+from .identity import generate
+from .poller import Poller
+from .session import SessionConnector
+from .session_manager import SessionManager
+from .types import Meta, RouteKey, SessionID
+
+if TYPE_CHECKING:
+    from .config import Config
+
+log = logging.getLogger("textual-web")
+
+DISCONNECT_RESIZE = (132, 45)
+
+WEBTERM_STATIC_PATH = Path(__file__).parent / "static"
+
+
+def _get_static_path() -> Path | None:
+    """Get the path to static assets from textual-serve."""
+    try:
+        import textual_serve
+
+        static_path = Path(textual_serve.__file__).parent / "static"
+        if static_path.exists():
+            return static_path
+    except ImportError:
+        log.warning("textual-serve not installed - static assets unavailable")
+    return None
+
+
+STATIC_PATH = _get_static_path()
+
+
+class LocalClientConnector(SessionConnector):
+    """Local connector that handles communication between sessions and local server."""
+
+    def __init__(self, server: LocalServer, session_id: SessionID, route_key: RouteKey) -> None:
+        self.server = server
+        self.session_id = session_id
+        self.route_key = route_key
+
+    async def on_data(self, data: bytes) -> None:
+        await self.server.handle_session_data(self.route_key, data)
+
+    async def on_meta(self, meta: Meta) -> None:
+        meta_type = meta.get("type")
+        if meta_type == "open_url":
+            log.info("App requested to open URL: %s", meta.get("url"))
+        elif meta_type == "deliver_file_start":
+            log.info("App requested file delivery: %s", meta.get("path"))
+        else:
+            log.debug("Unknown meta type: %r. Full meta: %r", meta_type, meta)
+
+    async def on_binary_encoded_message(self, payload: bytes) -> None:
+        await self.server.handle_binary_message(self.route_key, payload)
+
+    async def on_close(self) -> None:
+        await self.server.handle_session_close(self.session_id, self.route_key)
+
+
+class LocalServer:
+    """Manages local Textual apps and terminals without Ganglion server."""
+
+    def __init__(
+        self,
+        config_path: str,
+        config: Config,
+        host: str = "0.0.0.0",
+        port: int = 8080,
+        exit_on_idle: int = 0,
+        landing_apps: list | None = None,
+    ) -> None:
+        self.host = host
+        self.port = port
+
+        abs_path = Path(config_path).absolute()
+        path = abs_path if abs_path.is_dir() else abs_path.parent
+        self.config = config
+        self._websocket_server: aiohttp.web.WebSocketResponse | None = None
+        self._poller = Poller()
+        self.session_manager = SessionManager(self._poller, path, config.apps)
+        self.exit_event = asyncio.Event()
+        self._task: asyncio.Task | None = None
+        self._shutdown_task: asyncio.Task | None = None
+        self._shutdown_started = False
+        self._loop: asyncio.AbstractEventLoop | None = None
+        self._exit_poller = ExitPoller(self, idle_wait=exit_on_idle)
+
+        self._websocket_connections: dict[RouteKey, web.WebSocketResponse] = {}
+        self._landing_apps = landing_apps or []
+
+    @property
+    def app_count(self) -> int:
+        return len(self.session_manager.apps)
+
+    def add_app(self, name: str, command: str, slug: str = "") -> None:
+        slug = slug or generate().lower()
+        self.session_manager.add_app(name, command, slug=slug)
+
+    def add_terminal(self, name: str, command: str, slug: str = "") -> None:
+        if constants.WINDOWS:
+            log.warning("Sorry, textual-web does not currently support terminals on Windows")
+            return
+        slug = slug or generate().lower()
+        self.session_manager.add_app(name, command, slug=slug, terminal=True)
+
+    async def run(self) -> None:
+        try:
+            await self._run()
+        finally:
+            self._exit_poller.stop()
+            if not constants.WINDOWS:
+                with contextlib.suppress(Exception):
+                    self._poller.exit()
+
+    def on_keyboard_interrupt(self) -> None:
+        print("\r\033[F")
+        log.info("Exit requested")
+
+        if self._shutdown_started:
+            self.exit_event.set()
+            return
+        self._shutdown_started = True
+
+        # Ensure we shut down sessions and websockets before stopping the server.
+        try:
+            loop = asyncio.get_running_loop()
+        except RuntimeError:
+            loop = None
+
+        if loop is not None:
+            if self._shutdown_task is None or self._shutdown_task.done():
+                self._shutdown_task = asyncio.create_task(self._shutdown())
+            return
+
+        if self._loop is not None and self._loop.is_running():
+            if self._shutdown_task is None or self._shutdown_task.done():
+
+                def _schedule() -> None:
+                    self._shutdown_task = asyncio.create_task(self._shutdown())
+
+                self._loop.call_soon_threadsafe(_schedule)
+            return
+
+        self.exit_event.set()
+
+    async def _run(self) -> None:
+        loop = asyncio.get_event_loop()
+        self._loop = loop
+
+        if constants.WINDOWS:
+
+            def exit_handler(_sig, _frame) -> None:
+                self.on_keyboard_interrupt()
+
+            signal.signal(signal.SIGINT, exit_handler)
+        else:
+            loop.add_signal_handler(signal.SIGINT, self.on_keyboard_interrupt)
+            self._poller.set_loop(loop)
+            self._poller.start()
+
+        self._task = asyncio.create_task(self._run_local_server())
+        self._exit_poller.start()
+        with contextlib.suppress(asyncio.CancelledError):
+            await self._task
+
+    def _build_routes(self) -> list[web.AbstractRouteDef]:
+        routes: list[web.AbstractRouteDef] = [
+            web.get("/ws/{route_key}", self._handle_websocket),
+            web.get("/screenshot.svg", self._handle_screenshot),
+            web.get("/health", self._handle_health_check),
+            web.get("/", self._handle_root),
+        ]
+
+        if STATIC_PATH is not None and STATIC_PATH.exists():
+            routes.append(web.static("/static", STATIC_PATH))
+            log.info("Static assets served from: %s", STATIC_PATH)
+        else:
+            log.error("Static assets not found at %s - terminal UI will not work", STATIC_PATH)
+
+        if WEBTERM_STATIC_PATH.exists():
+            routes.append(web.static("/static-webterm", WEBTERM_STATIC_PATH))
+
+        return routes
+
+    async def _shutdown(self) -> None:
+        try:
+            for ws in list(self._websocket_connections.values()):
+                with contextlib.suppress(Exception):
+                    await ws.close()
+            await self.session_manager.close_all()
+        finally:
+            self.exit_event.set()
+
+    async def _run_local_server(self) -> None:
+        app = web.Application()
+        app.add_routes(self._build_routes())
+
+        runner = web.AppRunner(app)
+        try:
+            await runner.setup()
+            site = web.TCPSite(runner, self.host, self.port)
+            await site.start()
+
+            log.info("Local server started on %s:%s", self.host, self.port)
+            log.info("Available apps: %s", ", ".join(app.name for app in self.session_manager.apps))
+
+            await self.exit_event.wait()
+        finally:
+            await runner.cleanup()
+
+    async def _dispatch_ws_message(
+        self,
+        envelope: list,
+        route_key: str,
+        ws: web.WebSocketResponse,
+        session_created: bool,
+    ) -> bool:
+        msg_type = envelope[0]
+
+        if msg_type == "stdin":
+            data = envelope[1] if len(envelope) > 1 else ""
+            session_process = self.session_manager.get_session_by_route_key(RouteKey(route_key))
+            if session_process:
+                await session_process.send_bytes(data.encode("utf-8"))
+
+        elif msg_type == "resize":
+            size_data = envelope[1] if len(envelope) > 1 else {}
+            width = max(1, min(500, int(size_data.get("width", 80))))
+            height = max(1, min(500, int(size_data.get("height", 24))))
+
+            if not session_created:
+                await self._create_terminal_session(route_key, width, height)
+                session_created = True
+            else:
+                session_process = self.session_manager.get_session_by_route_key(RouteKey(route_key))
+                if session_process:
+                    await session_process.set_terminal_size(width, height)
+
+        elif msg_type == "ping":
+            data = envelope[1] if len(envelope) > 1 else ""
+            await ws.send_json(["pong", data])
+
+        return session_created
+
+    async def _resize_on_disconnect(self, route_key: str) -> None:
+        session_process = self.session_manager.get_session_by_route_key(RouteKey(route_key))
+        if session_process is None or not hasattr(session_process, "set_terminal_size"):
+            return
+        width, height = DISCONNECT_RESIZE
+        with contextlib.suppress(OSError):
+            await session_process.set_terminal_size(width, height)
+
+    async def _handle_websocket(self, request: web.Request) -> web.WebSocketResponse:
+        route_key = request.match_info["route_key"]
+        ws = web.WebSocketResponse(heartbeat=30.0, max_msg_size=64 * 1024)
+        await ws.prepare(request)
+
+        log.info("WebSocket connection established for route %s", route_key)
+        self._websocket_connections[route_key] = ws
+
+        session_id = self.session_manager.routes.get(RouteKey(route_key))
+        if session_id is not None:
+            session = self.session_manager.get_session(session_id)
+            if session is None or not session.is_running():
+                self.session_manager.on_session_end(session_id)
+                session_id = None
+
+        session_created = session_id is not None
+
+        try:
+            async for msg in ws:
+                if msg.type == WSMsgType.TEXT:
+                    try:
+                        envelope = json.loads(msg.data)
+                        if not isinstance(envelope, list) or len(envelope) < 1:
+                            continue
+                        session_created = await self._dispatch_ws_message(
+                            envelope, route_key, ws, session_created
+                        )
+                    except Exception as e:
+                        log.error("Error processing WebSocket message: %s", e)
+                elif msg.type == WSMsgType.ERROR:
+                    log.error("WebSocket connection error for route %s", route_key)
+                    break
+        finally:
+            log.info("WebSocket connection closed for route %s", route_key)
+            self._websocket_connections.pop(route_key, None)
+            await self._resize_on_disconnect(route_key)
+
+        return ws
+
+    def _select_app_for_route(self, route_key: str):
+        """Pick the app matching the route key, or fall back to default."""
+        app = self.session_manager.apps_by_slug.get(route_key)
+        return app or self.session_manager.get_default_app()
+
+    async def _create_terminal_session(self, route_key: str, width: int, height: int) -> None:
+        available_app = self._select_app_for_route(route_key)
+        if available_app is None:
+            log.error("No app available for route %s", route_key)
+            ws = self._websocket_connections.get(route_key)
+            if ws:
+                await ws.send_json(["error", "No app configured"])
+            return
+
+        session_id = SessionID(generate())
+        log.info(
+            "Creating %s session %s for route %s (%sx%s)",
+            "terminal" if available_app.terminal else "app",
+            session_id,
+            route_key,
+            width,
+            height,
+        )
+
+        session_process = await self.session_manager.new_session(
+            available_app.slug,
+            session_id,
+            RouteKey(route_key),
+            size=(width, height),
+        )
+
+        if session_process is None:
+            log.error("Failed to create session for route %s", route_key)
+            ws = self._websocket_connections.get(route_key)
+            if ws:
+                await ws.send_json(["error", "Failed to create session"])
+            return
+
+        connector = LocalClientConnector(self, session_id, RouteKey(route_key))
+        await session_process.start(connector)
+
+    async def _handle_screenshot(self, request: web.Request) -> web.Response:
+        route_key = request.query.get("route_key")
+        if route_key is None:
+            running = self.session_manager.get_first_running_session()
+            if running:
+                route_key = str(running[0])
+
+        if route_key is None:
+            raise web.HTTPNotFound(text="No running session")
+
+        session_process = self.session_manager.get_session_by_route_key(RouteKey(route_key))
+        if session_process is None and route_key in self.session_manager.apps_by_slug:
+            await self._create_terminal_session(
+                route_key,
+                width=DISCONNECT_RESIZE[0],
+                height=DISCONNECT_RESIZE[1],
+            )
+            session_process = self.session_manager.get_session_by_route_key(RouteKey(route_key))
+
+        if session_process is None or not hasattr(session_process, "get_replay_buffer"):
+            raise web.HTTPNotFound(text="Session not found")
+
+        replay_data = await session_process.get_replay_buffer()  # type: ignore[func-returns-value]
+        ansi_text = replay_data.decode("utf-8", errors="replace")
+
+        try:
+            width = int(request.query.get("width", "120"))
+        except ValueError:
+            width = 120
+        width = max(10, min(400, width))
+
+        try:
+            height = int(request.query.get("height", str(DISCONNECT_RESIZE[1])))
+        except ValueError:
+            height = DISCONNECT_RESIZE[1]
+        height = max(5, min(200, height))
+
+        lines = ansi_text.splitlines()
+        if len(lines) > height:
+            ansi_text = "\n".join(lines[-height:]) + "\n"
+
+        console = Console(record=True, width=width, height=height, file=io.StringIO())
+        decoder = AnsiDecoder()
+        for renderable in decoder.decode(ansi_text):
+            console.print(renderable)
+
+        svg = console.export_svg(
+            title="textual-webterm",
+            code_format=(
+                '<svg class="rich-terminal" viewBox="0 0 {terminal_width} {terminal_height}" '
+                'xmlns="http://www.w3.org/2000/svg">'
+                '<style>{styles}</style>'
+                '<defs>'
+                '<clipPath id="{unique_id}-clip-terminal">'
+                '<rect x="0" y="0" width="{terminal_width}" height="{terminal_height}" />'
+                '</clipPath>'
+                '{lines}'
+                '</defs>'
+                '<g clip-path="url(#{unique_id}-clip-terminal)">'
+                '<rect x="0" y="0" width="{terminal_width}" height="{terminal_height}" fill="#000" />'
+                '{backgrounds}'
+                '<g class="{unique_id}-matrix">{matrix}</g>'
+                '</g>'
+                '</svg>'
+            ),
+        )
+        return web.Response(text=svg, content_type="image/svg+xml")
+
+    async def _handle_health_check(self, _request: web.Request) -> web.Response:
+        return web.Response(text="Local server is running")
+
+    def _get_ws_url_from_request(self, request: web.Request, route_key: str) -> str:
+        """Build WebSocket URL honoring reverse proxies and port mapping."""
+
+        forwarded_proto = request.headers.get("X-Forwarded-Proto", "").split(",")[0].strip().lower()
+        forwarded_host = request.headers.get("X-Forwarded-Host", "").split(",")[0].strip()
+        forwarded_port = request.headers.get("X-Forwarded-Port", "").split(",")[0].strip()
+
+        def _pick_proto() -> str:
+            if forwarded_proto in ("https", "wss"):
+                return "wss"
+            if forwarded_proto in ("http", "ws"):
+                return "ws"
+            return "wss" if request.secure else "ws"
+
+        def _split_host_port(host: str) -> tuple[str, str]:
+            if not host:
+                return "", ""
+            if ":" in host:
+                return host.rsplit(":", 1)
+            return host, ""
+
+        ws_proto = _pick_proto()
+        ws_host, ws_port = _split_host_port(forwarded_host)
+
+        if not ws_host:
+            host_header = request.headers.get("Host", "")
+            ws_host, ws_port = _split_host_port(host_header)
+
+        if not ws_host:
+            ws_host = "localhost" if self.host == "0.0.0.0" else self.host
+            ws_port = str(self.port)
+
+        if not ws_port and forwarded_port:
+            ws_port = forwarded_port
+
+        if ws_port and ws_port not in ("80", "443"):
+            return f"{ws_proto}://{ws_host}:{ws_port}/ws/{route_key}"
+        if not ws_port and self.port not in (80, 443):
+            return f"{ws_proto}://{ws_host}:{self.port}/ws/{route_key}"
+        return f"{ws_proto}://{ws_host}/ws/{route_key}"
+
+    async def _handle_root(self, request: web.Request) -> web.Response:
+        route_key_param = request.query.get("route_key")
+
+        if self._landing_apps and not route_key_param:
+            tiles = [
+                {"slug": app.slug, "name": app.name, "command": app.command}
+                for app in self._landing_apps
+            ]
+            tiles_json = json.dumps(tiles)
+            html_content = f"""<!DOCTYPE html>
+<html>
+<head>
+    <title>Textual WebTerm Dashboard</title>
+    <style>
+        body {{ font-family: Arial, sans-serif; margin: 16px; background: #0f172a; color: #e2e8f0; }}
+        h1 {{ margin-bottom: 8px; }}
+        .grid {{ display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 12px; }}
+        .tile {{ background: #1e293b; border: 1px solid #334155; border-radius: 8px; overflow: hidden; box-shadow: 0 2px 6px rgba(0,0,0,0.4); }}
+        .tile-header {{ padding: 10px 12px; font-weight: bold; border-bottom: 1px solid #334155; display: flex; align-items: center; gap: 8px; }}
+        .tile-body {{ padding: 0; }}
+        .thumb {{ width: 100%; height: 180px; object-fit: contain; background: #0b1220; display: block; }}
+        .meta {{ padding: 8px 12px; color: #94a3b8; font-size: 12px; }}
+        a {{ color: inherit; text-decoration: none; }}
+    </style>
+</head>
+<body>
+    <h1>Sessions</h1>
+    <div class=\"grid\" id=\"grid\"></div>
+    <script>
+        const tiles = {tiles_json};
+        function makeTile(tile) {{
+            const card = document.createElement('div');
+            card.className = 'tile';
+            const header = document.createElement('div');
+            header.className = 'tile-header';
+            header.innerHTML = `<span>${{tile.name}}</span>`;
+            const body = document.createElement('div');
+            body.className = 'tile-body';
+            const img = document.createElement('img');
+            img.className = 'thumb';
+            img.alt = tile.name;
+            const meta = document.createElement('div');
+            meta.className = 'meta';
+            meta.innerText = tile.command;
+            body.appendChild(img);
+            card.appendChild(header);
+            card.appendChild(body);
+            card.appendChild(meta);
+            card.onclick = () => {{
+                window.open(`/?route_key=${{encodeURIComponent(tile.slug)}}`, '_blank');
+            }};
+            card.img = img;
+            return card;
+        }}
+        const grid = document.getElementById('grid');
+        const cards = tiles.map(makeTile);
+        cards.forEach(c => grid.appendChild(c));
+        async function refresh() {{
+            for (const card of cards) {{
+                const tile = tiles[cards.indexOf(card)];
+                const url = `/screenshot.svg?route_key=${{encodeURIComponent(tile.slug)}}&t=${{Date.now()}}`;
+                card.img.src = url;
+            }}
+        }}
+
+        let refreshTimer = null;
+        function startRefresh() {{
+            if (refreshTimer !== null) return;
+            refresh();
+            refreshTimer = setInterval(refresh, 15000);
+        }}
+        function stopRefresh() {{
+            if (refreshTimer === null) return;
+            clearInterval(refreshTimer);
+            refreshTimer = null;
+        }}
+
+        document.addEventListener('visibilitychange', () => {{
+            if (document.hidden) stopRefresh();
+            else startRefresh();
+        }});
+
+        if (!document.hidden) startRefresh();
+    </script>
+</body>
+</html>"""
+            return web.Response(text=html_content, content_type="text/html")
+
+        available_app = None
+        if route_key_param:
+            available_app = self.session_manager.apps_by_slug.get(route_key_param)
+        if available_app is None:
+            available_app = self.session_manager.get_default_app()
+        if available_app is None:
+            html_content = """<!DOCTYPE html>
+<html>
+<head>
+    <title>Textual Web Terminal Server</title>
+</head>
+<body>
+    <h2>No Apps Available</h2>
+    <p>No terminal or Textual applications are configured.</p>
+</body>
+</html>"""
+            return web.Response(text=html_content, content_type="text/html")
+
+        route_key: RouteKey | None = None
+        if route_key_param:
+            route_key = RouteKey(route_key_param)
+        else:
+            running = self.session_manager.get_first_running_session()
+            if running:
+                route_key = running[0]
+
+        if route_key is None:
+            route_key = RouteKey(generate().lower())
+
+        ws_url = self._get_ws_url_from_request(request, route_key)
+
+        html_content = f"""<!DOCTYPE html>
+<html>
+<head>
+    <title>Textual Web Terminal</title>
+    <link rel=\"stylesheet\" href=\"/static/css/xterm.css\">
+    <link rel=\"stylesheet\" href=\"/static-webterm/monospace.css\">
+    <script src=\"/static/js/textual.js\"></script>
+    <style>
+      body {{ background: #000; margin: 0; padding: 0; }}
+    </style>
+</head>
+<body>
+    <div class=\"textual-terminal\" data-session-websocket-url={ws_url!r} data-font-size=\"16\"></div>
+</body>
+</html>"""
+        return web.Response(text=html_content, content_type="text/html")
+
+    async def handle_session_data(self, route_key: RouteKey, data: bytes) -> None:
+        ws = self._websocket_connections.get(route_key)
+        if ws is None:
+            return
+        await ws.send_bytes(data)
+
+    async def handle_binary_message(self, route_key: RouteKey, payload: bytes) -> None:
+        ws = self._websocket_connections.get(route_key)
+        if ws is None:
+            return
+        await ws.send_bytes(payload)
+
+    async def handle_session_close(self, session_id: SessionID, route_key: RouteKey) -> None:
+        self.session_manager.on_session_end(session_id)
+        ws = self._websocket_connections.get(route_key)
+        if ws is not None:
+            with contextlib.suppress(Exception):
+                await ws.close()
+
+    def force_exit(self) -> None:
+        self.exit_event.set()

src/textual_webterm/poller.py

@@ -0,0 +1,129 @@
+from __future__ import annotations
+
+import asyncio
+import os
+import selectors
+from collections import deque
+from dataclasses import dataclass, field
+from threading import Event, Thread
+
+
+@dataclass
+class Write:
+    """Data in a write queue."""
+
+    data: bytes
+    position: int = 0
+    done_event: asyncio.Event = field(default_factory=asyncio.Event)
+
+
+class Poller(Thread):
+    """A thread which reads from file descriptors and posts read data to a queue."""
+
+    def __init__(self) -> None:
+        super().__init__()
+        self._loop: asyncio.AbstractEventLoop | None = None
+        self._selector = selectors.DefaultSelector()
+        self._read_queues: dict[int, asyncio.Queue[bytes | None]] = {}
+        self._write_queues: dict[int, deque[Write]] = {}
+        self._exit_event = Event()
+
+    def add_file(self, file_descriptor: int) -> asyncio.Queue:
+        """Add a file descriptor to the poller.
+
+        Args:
+            file_descriptor: File descriptor.
+
+        Returns:
+            Async queue.
+        """
+        self._selector.register(file_descriptor, selectors.EVENT_READ | selectors.EVENT_WRITE)
+        queue = self._read_queues[file_descriptor] = asyncio.Queue()
+        return queue
+
+    def remove_file(self, file_descriptor: int) -> None:
+        """Remove a file descriptor from the poller.
+
+        Args:
+            file_descriptor: File descriptor.
+        """
+        self._selector.unregister(file_descriptor)
+        self._read_queues.pop(file_descriptor, None)
+        self._write_queues.pop(file_descriptor, None)
+
+    async def write(self, file_descriptor: int, data: bytes) -> None:
+        """Write data to a file descriptor.
+
+        Args:
+            file_descriptor: File descriptor.
+            data: Data to write.
+        """
+        if file_descriptor not in self._write_queues:
+            self._write_queues[file_descriptor] = deque()
+        new_write = Write(data)
+        self._write_queues[file_descriptor].append(new_write)
+        self._selector.modify(file_descriptor, selectors.EVENT_READ | selectors.EVENT_WRITE)
+        await new_write.done_event.wait()
+
+    def set_loop(self, loop: asyncio.AbstractEventLoop) -> None:
+        """Set the asyncio loop.
+
+        Args:
+            loop: Async loop.
+        """
+        self._loop = loop
+
+    def run(self) -> None:
+        """Run the Poller thread."""
+
+        readable_events = selectors.EVENT_READ
+        writeable_events = selectors.EVENT_WRITE
+
+        loop = self._loop
+        selector = self._selector
+        assert loop is not None
+        while not self._exit_event.is_set():
+            events = selector.select(1)
+
+            for selector_key, event_mask in events:
+                file_descriptor = selector_key.fileobj
+                assert isinstance(file_descriptor, int)
+
+                queue = self._read_queues.get(file_descriptor, None)
+                if queue is not None:
+                    if event_mask & readable_events:
+                        try:
+                            data = os.read(file_descriptor, 1024 * 32) or None
+                        except OSError:
+                            loop.call_soon_threadsafe(queue.put_nowait, None)
+                        else:
+                            loop.call_soon_threadsafe(queue.put_nowait, data)
+
+                    if event_mask & writeable_events:
+                            write_queue = self._write_queues.get(file_descriptor, None)
+                            if write_queue:
+                                write = write_queue[0]
+                                remaining_data = write.data[write.position :]
+                                try:
+                                    bytes_written = os.write(file_descriptor, remaining_data)
+                                except OSError:
+                                    # Write failed; signal completion anyway to unblock waiters
+                                    write_queue.popleft()
+                                    loop.call_soon_threadsafe(write.done_event.set)
+                                    continue
+                                write.position += bytes_written
+                                # Check if all data has been written
+                                if write.position >= len(write.data):
+                                    write_queue.popleft()
+                                    loop.call_soon_threadsafe(write.done_event.set)
+                            else:
+                                selector.modify(file_descriptor, readable_events)
+
+    def exit(self) -> None:
+        """Exit and block until finished."""
+        for queue in self._read_queues.values():
+            queue.put_nowait(None)
+        self._exit_event.set()
+        self.join()
+        self._read_queues.clear()
+        self._write_queues.clear()

src/textual_webterm/session.py

@@ -0,0 +1,109 @@
+from __future__ import annotations
+
+from abc import abstractmethod
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    import asyncio
+
+    from .types import Meta
+
+
+class SessionConnector:
+    """Connect a session with a client."""
+
+    async def on_data(self, data: bytes) -> None:
+        """Handle data from session.
+
+        Args:
+            data: Bytes to handle.
+        """
+
+    async def on_meta(self, meta: Meta) -> None:
+        """Handle meta from session.
+
+        Args:
+            meta: Mapping of meta information.
+        """
+
+    async def on_binary_encoded_message(self, payload: bytes) -> None:
+        """Handle binary encoded data from the process.
+
+        Args:
+            payload: Binary encoded data to handle.
+        """
+
+    async def on_close(self) -> None:
+        """Handle session close."""
+
+
+class Session:
+    """Virtual base class for a session."""
+
+    def __init__(self) -> None:
+        self._connector = SessionConnector()
+
+    @abstractmethod
+    async def open(self, width: int = 80, height: int = 24) -> None:
+        """Open the session."""
+        ...
+
+    @abstractmethod
+    async def start(self, connector: SessionConnector) -> asyncio.Task:
+        """Start the session.
+
+        Returns:
+            Running task.
+        """
+        ...
+
+    @abstractmethod
+    async def close(self) -> None:
+        """Close the session."""
+
+    @abstractmethod
+    async def wait(self) -> None:
+        """Wait for session to end."""
+
+    @abstractmethod
+    async def set_terminal_size(self, width: int, height: int) -> None:
+        """Set the terminal size.
+
+        Args:
+            width: New width.
+            height: New height.
+        """
+        ...
+
+    @abstractmethod
+    async def send_bytes(self, data: bytes) -> bool:
+        """Send bytes to the process.
+
+        Args:
+            data: Bytes to send.
+
+        Returns:
+            True on success, or False if the data was not sent.
+        """
+        ...
+
+    @abstractmethod
+    async def send_meta(self, data: Meta) -> bool:
+        """Send meta to the process.
+
+        Args:
+            meta: Meta information.
+
+        Returns:
+            True on success, or False if the data was not sent.
+        """
+        ...
+
+    def is_running(self) -> bool:
+        """Check if the session is still running.
+
+        Returns:
+            True if session is active, False otherwise.
+        """
+        return False
+

src/textual_webterm/session_manager.py

@@ -0,0 +1,201 @@
+from __future__ import annotations
+
+import asyncio
+import logging
+import sys
+from typing import TYPE_CHECKING
+
+from . import config, constants
+from ._two_way_dict import TwoWayDict
+from .app_session import AppSession
+from .identity import generate
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+    from .poller import Poller
+    from .session import Session
+    from .types import RouteKey, SessionID
+
+
+log = logging.getLogger("textual-web")
+
+
+if not constants.WINDOWS:
+    from .terminal_session import TerminalSession
+
+
+class SessionManager:
+    """Manage sessions (Textual apps or terminals)."""
+
+    def __init__(self, poller: Poller, path: Path, apps: list[config.App]) -> None:
+        self.poller = poller
+        self.path = path
+        self.apps = apps
+        self.apps_by_slug = {app.slug: app for app in apps}
+        self.sessions: dict[SessionID, Session] = {}
+        self.routes: TwoWayDict[RouteKey, SessionID] = TwoWayDict()
+
+    def add_app(self, name: str, command: str, slug: str, terminal: bool = False) -> None:
+        """Add a new app
+
+        Args:
+            name: Name of the app.
+            command: Command to run the app.
+            slug: Slug used in URL, or blank to auto-generate on server.
+        """
+        slug = slug or generate().lower()
+        new_app = config.App(name=name, slug=slug, path="./", command=command, terminal=terminal)
+        self.apps.append(new_app)
+        self.apps_by_slug[slug] = new_app
+
+    def get_default_app(self) -> config.App | None:
+        """Get the default app (first configured app), or ``None``."""
+        return self.apps[0] if self.apps else None
+
+    def on_session_end(self, session_id: SessionID) -> None:
+        """Called when a session ends."""
+        self.sessions.pop(session_id, None)
+        route_key = self.routes.get_key(session_id)
+        if route_key is not None:
+            del self.routes[route_key]
+        log.debug(f"Session {session_id} ended")
+
+    async def close_all(self, timeout: float = 3.0) -> None:
+        """Close app sessions.
+
+        Args:
+            timeout: Time (in seconds) to wait before giving up.
+
+        """
+        sessions = list(self.sessions.values())
+
+        if not sessions:
+            return
+        log.info("Closing %s session(s)", len(sessions))
+
+        async def do_close() -> int:
+            """Close all sessions, return number unclosed after timeout
+
+            Returns:
+                Number of sessions not yet closed.
+            """
+
+            async def close_wait(session: Session) -> None:
+                await asyncio.gather(session.close(), session.wait())
+
+            if sys.version_info >= (3, 11):
+                async with asyncio.TaskGroup() as tg:  # type: ignore[attr-defined]
+                    for session in sessions:
+                        tg.create_task(close_wait(session))
+                return 0
+            _done, remaining = await asyncio.wait(
+                [asyncio.create_task(close_wait(session)) for session in sessions],
+                timeout=timeout,
+            )
+            return len(remaining)
+
+        remaining = await do_close()
+        if remaining:
+            log.warning("%s session(s) didn't close after %s seconds", remaining, timeout)
+
+    async def new_session(
+        self,
+        slug: str,
+        session_id: SessionID,
+        route_key: RouteKey,
+        size: tuple[int, int] = (80, 24),
+    ) -> Session | None:
+        """Create a new session.
+
+        Args:
+            slug: Slug for app.
+            session_id: Session identity.
+            route_key: Route key.
+            size: Terminal size (width, height).
+
+        Returns:
+            New session, or `None` if no app / terminal configured.
+        """
+        app = self.apps_by_slug.get(slug)
+        if app is None:
+            return None
+
+        session_process: Session
+        if app.terminal:
+            if constants.WINDOWS:
+                log.warning("Sorry, textual-web does not currently support terminals on Windows")
+                return None
+            else:
+                session_process = TerminalSession(
+                    self.poller,
+                    session_id,
+                    app.command,
+                )
+                log.info(f"Created terminal session {session_id}")
+        else:
+            session_process = AppSession(
+                self.path,
+                app.command,
+                session_id,
+            )
+            log.info(f"Created app session {session_id}")
+
+        self.sessions[session_id] = session_process
+        self.routes[route_key] = session_id
+
+        await session_process.open(*size)
+        log.debug(f"Session {session_id} opened and ready")
+
+        return session_process
+
+    async def close_session(self, session_id: SessionID) -> None:
+        """Close a session.
+
+        Args:
+            session_id: Session identity.
+        """
+        session_process = self.sessions.get(session_id, None)
+        if session_process is None:
+            return
+        await session_process.close()
+
+    def get_session(self, session_id: SessionID) -> Session | None:
+        """Get a session from a session ID.
+
+        Args:
+            session_id: Session identity.
+
+        Returns:
+            A session or `None` if it doesn't exist.
+        """
+        return self.sessions.get(session_id)
+
+    def get_session_by_route_key(self, route_key: RouteKey) -> Session | None:
+        """Get a session from a route key.
+
+        Args:
+            route_key: A route key.
+
+        Returns:
+            A session or `None` if it doesn't exist.
+
+        """
+        session_id = self.routes.get(route_key)
+        if session_id is not None:
+            return self.sessions.get(session_id)
+        return None
+
+    def get_first_running_session(self) -> tuple[RouteKey, Session] | None:
+        """Get the first running session.
+
+        Returns:
+            Tuple of (route_key, session) or None if no running sessions.
+        """
+        for route_key in self.routes:
+            session_id = self.routes.get(route_key)
+            if session_id:
+                session = self.sessions.get(session_id)
+                if session and session.is_running():
+                    return (route_key, session)
+        return None

src/textual_webterm/slugify.py

@@ -0,0 +1,18 @@
+import re
+import unicodedata
+
+
+def slugify(value: str, allow_unicode=False) -> str:
+    """
+    Convert to ASCII if 'allow_unicode' is False. Convert spaces or repeated
+    dashes to single dashes. Remove characters that aren't alphanumerics,
+    underscores, or hyphens. Convert to lowercase. Also strip leading and
+    trailing whitespace, dashes, and underscores.
+    """
+    value = str(value)
+    if allow_unicode:
+        value = unicodedata.normalize("NFKC", value)
+    else:
+        value = unicodedata.normalize("NFKD", value).encode("ascii", "ignore").decode("ascii")
+    value = re.sub(r"[^\w\s-]", "", value.lower())
+    return re.sub(r"[-\s]+", "-", value).strip("-_")

src/textual_webterm/static/monospace.css

@@ -0,0 +1,19 @@
+/* Generic monospace font stack for terminal rendering.
+
+Prefers system monospace fonts, with optional Fira Code / Roboto Mono if available.
+We avoid external font fetching (e.g. Google Fonts) to keep local server self-contained.
+*/
+
+:root {
+  --textual-webterm-mono: ui-monospace, "SFMono-Regular", "FiraCode Nerd Font",
+    "FiraMono Nerd Font", "Fira Code", "Roboto Mono", Menlo, Monaco, Consolas,
+    "Liberation Mono", "DejaVu Sans Mono", "Courier New", monospace;
+}
+
+body {
+  font-family: var(--textual-webterm-mono);
+}
+
+.xterm {
+  font-family: var(--textual-webterm-mono);
+}

src/textual_webterm/terminal_session.py

@@ -0,0 +1,180 @@
+from __future__ import annotations
+
+import array
+import asyncio
+import contextlib
+import fcntl
+import logging
+import os
+import pty
+import shlex
+import signal
+import termios
+from collections import deque
+from typing import TYPE_CHECKING
+
+import rich.repr
+from importlib_metadata import version
+
+from .session import Session, SessionConnector
+
+if TYPE_CHECKING:
+    from .poller import Poller
+    from .types import Meta, SessionID
+
+log = logging.getLogger("textual-web")
+
+# Maximum bytes to keep in replay buffer for reconnection
+REPLAY_BUFFER_SIZE = 64 * 1024  # 64KB
+
+
+@rich.repr.auto
+class TerminalSession(Session):
+    """A session that manages a terminal."""
+
+    def __init__(
+        self,
+        poller: Poller,
+        session_id: SessionID,
+        command: str,
+    ) -> None:
+        self.poller = poller
+        self.session_id = session_id
+        self.command = command or os.environ.get("SHELL", "sh")
+        self.master_fd: int | None = None
+        self.pid: int | None = None
+        self._task: asyncio.Task | None = None
+        self._replay_buffer: deque[bytes] = deque()
+        self._replay_buffer_size = 0
+        self._replay_lock = asyncio.Lock()
+        super().__init__()
+
+    def __rich_repr__(self) -> rich.repr.Result:
+        yield "session_id", self.session_id
+        yield "command", self.command
+
+    async def open(self, width: int = 80, height: int = 24) -> None:
+        log.info(f"Opening terminal session {self.session_id} with command: {self.command}")
+        pid, master_fd = pty.fork()
+        self.pid = pid
+        self.master_fd = master_fd
+        if pid == pty.CHILD:
+            os.environ["TERM_PROGRAM"] = "textual-webterm"
+            os.environ["TERM_PROGRAM_VERSION"] = version("textual-webterm")
+            try:
+                argv = shlex.split(self.command)
+            except ValueError:
+                os._exit(1)
+            if not argv:
+                os._exit(1)
+            try:
+                os.execvp(argv[0], argv)  ## Exits the app
+            except OSError:
+                os._exit(1)
+        try:
+            self._set_terminal_size(width, height)
+        except OSError:
+            # Clean up on failure
+            os.close(master_fd)
+            self.master_fd = None
+            raise
+        log.debug(f"Terminal session {self.session_id} opened successfully")
+
+    def _set_terminal_size(self, width: int, height: int) -> None:
+        buf = array.array("h", [height, width, 0, 0])
+        assert self.master_fd is not None
+        fcntl.ioctl(self.master_fd, termios.TIOCSWINSZ, buf)
+
+    async def set_terminal_size(self, width: int, height: int) -> None:
+        loop = asyncio.get_running_loop()
+        await loop.run_in_executor(None, self._set_terminal_size, width, height)
+
+    async def _add_to_replay_buffer(self, data: bytes) -> None:
+        """Add data to replay buffer, maintaining size limit."""
+        async with self._replay_lock:
+            self._replay_buffer.append(data)
+            self._replay_buffer_size += len(data)
+            while self._replay_buffer_size > REPLAY_BUFFER_SIZE and self._replay_buffer:
+                old_data = self._replay_buffer.popleft()
+                self._replay_buffer_size -= len(old_data)
+
+    async def get_replay_buffer(self) -> bytes:
+        """Get the contents of the replay buffer."""
+        async with self._replay_lock:
+            return b"".join(self._replay_buffer)
+
+    def update_connector(self, connector: SessionConnector) -> None:
+        """Update the connector for reconnection without restarting the session."""
+        self._connector = connector
+        log.debug(f"Updated connector for session {self.session_id}")
+
+    async def start(self, connector: SessionConnector) -> asyncio.Task:
+        self._connector = connector
+        assert self.master_fd is not None
+        if self._task is not None:
+            # Already running, just update connector (handled by update_connector)
+            return self._task
+        self._task = asyncio.create_task(self.run())
+        return self._task
+
+    async def run(self) -> None:
+        assert self.master_fd is not None
+        queue = self.poller.add_file(self.master_fd)
+        try:
+            while True:
+                data = await queue.get()
+                if not data:
+                    break
+                # Store in replay buffer for reconnection
+                await self._add_to_replay_buffer(data)
+                # Send to current connector
+                if self._connector:
+                    await self._connector.on_data(data)
+        except OSError:
+            log.exception("error in terminal.run")
+        finally:
+            if self._connector:
+                await self._connector.on_close()
+            if self.master_fd is not None:
+                fd = self.master_fd
+                self.master_fd = None
+                # Remove from poller first (while fd is still valid), then close
+                self.poller.remove_file(fd)
+                os.close(fd)
+
+    async def send_bytes(self, data: bytes) -> bool:
+        if self.master_fd is None:
+            return False
+        await self.poller.write(self.master_fd, data)
+        return True
+
+    async def send_meta(self, data: Meta) -> bool:
+        return True
+
+    async def close(self) -> None:
+        if self.pid is not None:
+            try:
+                os.kill(self.pid, signal.SIGHUP)
+            except ProcessLookupError:
+                pass  # Process already gone
+            except Exception as e:
+                log.warning(f"Error closing terminal session {self.session_id}: {e}")
+
+    async def wait(self) -> None:
+        if self._task is not None:
+            with contextlib.suppress(asyncio.CancelledError):
+                await self._task
+
+    def is_running(self) -> bool:
+        """Check if the terminal session is still running."""
+        if self.master_fd is None or self._task is None:
+            return False
+        # Check if process is actually alive
+        if self.pid is not None:
+            try:
+                os.kill(self.pid, 0)  # Signal 0 checks existence
+                return True
+            except OSError:
+                return False
+        # pid is None means process not started or already exited
+        return False

src/textual_webterm/types.py

@@ -0,0 +1,6 @@
+from typing import NewType, Union
+
+AppID = NewType("AppID", str)
+Meta = dict[str, Union[str, None, int, bool]]
+RouteKey = NewType("RouteKey", str)
+SessionID = NewType("SessionID", str)