refactor: modularize auth transport and markdown

- Split auth into focused package modules for agent keys, file keys,
  signing, and post-quantum transport helpers while keeping the public
  browser_cli.auth import surface intact.
- Move transport encoding internals into a package with separate codec and
  binary-hoisting helpers, preserving browser_cli.transport compatibility.
- Extract remote TCP auth/socket helpers and serve challenge setup out of the
  runtime paths to make connection handling easier to reason about.
- Move the extension markdown extractor into a dedicated content/markdown
  folder with separate root selection, code normalization, renderer, and utils.
- Centralize CLI Rich rendering helpers for tab/window tree and table output,
  and add rendering tests for the shared builders.
- Remove local typing ignores in SDK/decorator/script plumbing and bump the
  package and extension version to 0.15.3.

browser_cli/remote/transport.py

@@ -1,202 +1,43 @@
 """TCP/TLS transport for talking to a remote ``browser-cli serve``.
 
-Owns the wire mechanics of the remote leg: open a socket (TLS on :443),
-complete the signed challenge/response handshake with an optional post-quantum
-key exchange, frame the request, and read the framed (possibly encrypted)
-response. The higher-level "which endpoint / which profile / which key"
-decisions stay in :mod:`browser_cli.client.core`.
+This module keeps the public/private compatibility surface used by older tests
+and callers, while delegating socket mechanics and auth-handshake details to
+focused helper modules.
 """
 from __future__ import annotations
 
-import asyncio
 import json
-import socket
-import sys
-from collections.abc import Callable
-from contextlib import contextmanager
-from typing import TypeVar
 
-from browser_cli.errors import BrowserNotConnected
-from browser_cli.endpoints import _resolve_connect_endpoint
-from browser_cli.framing import async_recv_exact, async_recv_frame, async_send_frame, frame, recv_exact, recv_frame
-from browser_cli.version_manager import USER_AGENT as _USER_AGENT
-
-T = TypeVar("T")
-_AUTH_FIELDS = {"token", "pubkey", "sig", "pq_kex", "encrypted", "_suppress_pq_warning"}
-_PQ_WARNING = (
-  "** WARNING: connection is not using a post-quantum key exchange algorithm.\n"
-  "** This session may be vulnerable to store now, decrypt later attacks.\n"
+from browser_cli.framing import async_send_frame, frame
+from browser_cli.remote.auth import (
+  build_auth_message as _build_auth_message,
+  build_auth_message_async as _build_auth_message_async,
+  decode_pq_response as _decode_pq_response,
+  parse_challenge as _parse_challenge,
+  should_warn_no_pq as _should_warn_no_pq,
+  with_challenge as _with_challenge,
+)
+from browser_cli.remote.socket import (
+  async_recv_all as _async_recv_all,
+  async_recv_exact_bytes as _async_recv_exact,
+  open_async_connection as _open_async_connection,
+  open_socket as _open_socket,
+  recv_all as _recv_all,
+  recv_exact_bytes as _recv_exact,
+  split_endpoint as _split_endpoint,
 )
 
-def _recv_exact(sock: socket.socket, n: int) -> bytes:
-  return recv_exact(sock, n) or b""
+def _send_remote(endpoint: str, msg: dict, private_key=None, *, warn_no_pq: bool | None = None) -> bytes | None:
+  warn = _should_warn_no_pq(msg) if warn_no_pq is None else warn_no_pq
 
-def _recv_all(sock: socket.socket) -> bytes:
-  return recv_frame(sock, label="Response") or b""
-
-async def _async_recv_exact(reader: asyncio.StreamReader, n: int) -> bytes:
-  return await async_recv_exact(reader, n) or b""
-
-async def _async_recv_all(reader: asyncio.StreamReader) -> bytes:
-  return await async_recv_frame(reader, label="Response") or b""
-
-def _split_endpoint(endpoint: str) -> tuple[str, int]:
-  connect_ep = _resolve_connect_endpoint(endpoint)
-  host, _, port_str = connect_ep.rpartition(":")
-  return host, int(port_str)
-
-@contextmanager
-def _open_socket(endpoint: str):
-  host, port = _split_endpoint(endpoint)
-  raw_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-  raw_sock.settimeout(30)
-  try:
-    raw_sock.connect((host, port))
-    if port == 443:
-      import ssl
-      sock = ssl.create_default_context().wrap_socket(raw_sock, server_hostname=host)
-    else:
-      sock = raw_sock
-  except Exception:
-    raw_sock.close()
-    raise
-  with sock:
-    yield sock
-
-async def _open_async_connection(endpoint: str) -> tuple[asyncio.StreamReader, asyncio.StreamWriter]:
-  host, port = _split_endpoint(endpoint)
-  ssl_ctx = None
-  if port == 443:
-    import ssl
-    ssl_ctx = ssl.create_default_context()
-  return await asyncio.open_connection(host, port, ssl=ssl_ctx, server_hostname=host if ssl_ctx else None)
-
-def _parse_challenge(raw: bytes) -> tuple[dict | None, str | None]:
-  try:
-    challenge = json.loads(raw)
-    nonce_hex = challenge.get("nonce") if challenge.get("type") == "challenge" else None
-    return challenge, nonce_hex
-  except (json.JSONDecodeError, AttributeError):
-    return None, None
-
-def _check_min_client_version(challenge: dict | None) -> None:
-  min_ver = challenge.get("min_client_version") if isinstance(challenge, dict) else None
-  if not min_ver:
-    return
-  from browser_cli.version_manager import parse_version
-  try:
-    client_ver = _USER_AGENT.split("/", 1)[1]
-    if parse_version(client_ver) < parse_version(min_ver):
-      raise BrowserNotConnected(
-        f"Client version {client_ver} is too old for this server "
-        f"(requires >= {min_ver}). Run: pip install --upgrade browser-cli"
-      )
-  except (IndexError, ValueError):
-    pass
-
-def _clean_message(msg: dict) -> dict:
-  return {k: v for k, v in msg.items() if k not in _AUTH_FIELDS}
-
-def _get_pq_public_key(challenge: dict | None) -> str | None:
-  if not isinstance(challenge, dict):
-    return None
-  from browser_cli.auth import PQ_KEX_ALG
-  kex = challenge.get("pq_kex")
-  if isinstance(kex, dict) and kex.get("alg") == PQ_KEX_ALG and kex.get("public_key"):
-    return str(kex["public_key"])
-  return None
-
-def _signed_payload(clean_msg: dict, private_key, nonce_hex: str, pq_shared_secret: bytes | None) -> dict:
-  from browser_cli.auth import PQ_KEX_ALG, pq_encrypt, public_key_hex, sign
-
-  nonce = bytes.fromhex(nonce_hex)
-  sig = sign(private_key, nonce, clean_msg, pq_shared_secret)
-  pubkey = public_key_hex(private_key)
-  if pq_shared_secret is None:
-    return {**clean_msg, "pubkey": pubkey, "sig": sig.hex()}
-
-  encrypted = pq_encrypt(pq_shared_secret, "request", json.dumps(clean_msg).encode("utf-8"))
-  return {
-    "id": clean_msg.get("id"),
-    "user_agent": clean_msg.get("user_agent"),
-    "pubkey": pubkey,
-    "sig": sig.hex(),
-    "pq_kex": clean_msg["pq_kex"],
-    "encrypted": encrypted,
-  }
-
-def _warn_no_pq(enabled: bool) -> None:
-  if enabled:
-    sys.stderr.write(_PQ_WARNING)
-
-def _build_auth_message(
-  msg: dict,
-  challenge: dict | None,
-  nonce_hex: str | None,
-  private_key,
-  encapsulate: Callable[[str], tuple[str, bytes]],
-  *,
-  warn_no_pq: bool = True,
-) -> tuple[dict, bytes | None]:
-  if not nonce_hex or private_key is None:
-    _warn_no_pq(warn_no_pq)
-    return msg, None
-
-  clean_msg = _clean_message(msg)
-  pq_shared_secret = None
-  pq_public_key = _get_pq_public_key(challenge)
-  if pq_public_key:
-    from browser_cli.auth import PQ_KEX_ALG
-    ciphertext_hex, pq_shared_secret = encapsulate(pq_public_key)
-    clean_msg["pq_kex"] = {"alg": PQ_KEX_ALG, "ciphertext": ciphertext_hex}
-  else:
-    _warn_no_pq(warn_no_pq)
-
-  return _signed_payload(clean_msg, private_key, nonce_hex, pq_shared_secret), pq_shared_secret
-
-async def _build_auth_message_async(
-  msg: dict,
-  challenge: dict | None,
-  nonce_hex: str | None,
-  private_key,
-  *,
-  warn_no_pq: bool = True,
-) -> tuple[dict, bytes | None]:
-  def encapsulate(public_key: str) -> tuple[str, bytes]:
+  def build_auth(sync_msg: dict, challenge: dict | None, nonce_hex: str | None, key):
     from browser_cli.auth import pq_kex_client_encapsulate
-    return pq_kex_client_encapsulate(public_key)
+    return _build_auth_message(sync_msg, challenge, nonce_hex, key, pq_kex_client_encapsulate, warn_no_pq=warn)
 
-  return await asyncio.to_thread(
-    _build_auth_message,
-    msg,
-    challenge,
-    nonce_hex,
-    private_key,
-    encapsulate,
-    warn_no_pq=warn_no_pq,
-  )
-
-def _decode_pq_response(response: bytes | None, pq_shared_secret: bytes | None) -> bytes | None:
-  if response is None or pq_shared_secret is None:
-    return response
-  try:
-    from browser_cli.auth import pq_decrypt
-    envelope = json.loads(response)
-    if isinstance(envelope, dict) and "encrypted" in envelope:
-      return pq_decrypt(pq_shared_secret, "response", envelope["encrypted"])
-  except Exception as e:
-    raise BrowserNotConnected(f"Cannot decrypt post-quantum remote response: {e}") from e
-  return response
-
-def _with_challenge(challenge_raw: bytes, msg: dict, private_key, build_auth: Callable[[dict, dict | None, str | None, object], T]) -> T:
-  if challenge_raw is None:
-    raise BrowserNotConnected("No challenge received from remote endpoint")
-  challenge, nonce_hex = _parse_challenge(challenge_raw)
-  _check_min_client_version(challenge)
-  return build_auth(msg, challenge, nonce_hex, private_key)
-
-def _should_warn_no_pq(msg: dict) -> bool:
-  return not bool(msg.pop("_suppress_pq_warning", False))
+  with _open_socket(endpoint) as sock:
+    payload_msg, pq_shared_secret = _with_challenge(_recv_all(sock), msg, private_key, build_auth)
+    sock.sendall(frame(json.dumps(payload_msg).encode("utf-8")))
+    return _decode_pq_response(_recv_all(sock), pq_shared_secret)
 
 async def _send_remote_async(endpoint: str, msg: dict, private_key=None, *, warn_no_pq: bool | None = None) -> bytes | None:
   reader, writer = await _open_async_connection(endpoint)
@@ -216,15 +57,3 @@ async def _send_remote_async(endpoint: str, msg: dict, private_key=None, *, warn
       await writer.wait_closed()
     except Exception:
       pass
-
-def _send_remote(endpoint: str, msg: dict, private_key=None, *, warn_no_pq: bool | None = None) -> bytes | None:
-  warn = _should_warn_no_pq(msg) if warn_no_pq is None else warn_no_pq
-
-  def build_auth(sync_msg: dict, challenge: dict | None, nonce_hex: str | None, key):
-    from browser_cli.auth import pq_kex_client_encapsulate
-    return _build_auth_message(sync_msg, challenge, nonce_hex, key, pq_kex_client_encapsulate, warn_no_pq=warn)
-
-  with _open_socket(endpoint) as sock:
-    payload_msg, pq_shared_secret = _with_challenge(_recv_all(sock), msg, private_key, build_auth)
-    sock.sendall(frame(json.dumps(payload_msg).encode("utf-8")))
-    return _decode_pq_response(_recv_all(sock), pq_shared_secret)