fix(cli): make the command-line client work on Windows

Its suite had only run on Linux. On Windows, against a real hub and node and
from the installed meshbay-cli.exe:

- secrets.enc was written in text mode (os.open without O_BINARY): every 0x0A
  of the ciphertext became CR LF and the saved session "does not open with
  its key" on the next run.
- isatty() is true for NUL, so a script run with `< NUL` or by the Task
  Scheduler was asked questions instead of told to pass --yes;
  output.terminal() checks for a real console.
- Ctrl+C waited for the selector loop's next timer, up to half a minute in
  `chat --follow`; the loop now points the signal wakeup at its self-pipe,
  as the proactor does.
- Right-click copy and paste raised: asyncio cannot start a process on the
  selector loop; the clipboard tool runs in a thread.
- Tab completion of remote paths ran on the default (proactor) loop, which
  never opens a node, and wrote in the locale encoding; the PowerShell script
  now reads it as UTF-8.
- `get -R` into a folder past MAX_PATH died with a traceback; get, put, the
  resume file and the interactive mode use the extended form at each disk
  call, as the node does.
- `groups` showed a SQLite hub's naive UTC time as local time.

The opt-in end-to-end suite now runs on Windows (16 tests: Chrome found under
Program Files and started with the real environment, VLC as the player, Ctrl+C
through a console of its own, PowerShell 5.1 completion of an accented name).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/packages/meshbay-cli/src/meshbay_cli/client/store.py b/packages/meshbay-cli/src/meshbay_cli/client/store.py
index c48fe89..00ff9f3 100644
--- a/packages/meshbay-cli/src/meshbay_cli/client/store.py
+++ b/packages/meshbay-cli/src/meshbay_cli/client/store.py
@@ -63,7 +63,10 @@ def data_dir() -> Path:
 def _write_private(path: Path, data: bytes) -> None:
     """Atomically, readable by this user only."""
     tmp = path.with_name(path.name + ".tmp")
-    fd = os.open(tmp, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, 0o600)
+    # O_BINARY: without it Windows opens in text mode and writes every 0x0A of
+    # the ciphertext as CR LF, and the secrets no longer open.
+    flags = os.O_WRONLY | os.O_CREAT | os.O_TRUNC | getattr(os, "O_BINARY", 0)
+    fd = os.open(tmp, flags, 0o600)
     try:
         os.write(fd, data)
         os.fsync(fd)