Clean up the terminal and reconnect when SSH connections drop (#6661)

* Clean up the terminal and reconnect when SSH connections drop

A remote tmux, herdr, or editor arms terminal modes over the SSH pipe
(mouse tracking, focus reporting, the alternate screen) that only it can
disarm. When the connection dies instead of exiting cleanly, those modes
stay armed on the local terminal, and every mouse move floods the prompt
with escape-sequence junk.

Wrap ssh in a shell function that disarms those modes after every exit,
and automatically reconnects when an established interactive session
drops. Remote commands, configured RemoteCommands, and redirected stdin
never reconnect, so their side effects cannot replay, and the retry loop
runs in a subshell so Ctrl-C cancels both the in-flight attempt and the
loop.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Detect dead SSH connections within a minute

Without keepalives, ssh does not notice a dead peer until TCP gives up,
which can take hours of sitting on a hung terminal with remote-armed
terminal modes stuck on. Ship a client keepalive default so drops are
detected in about 45 seconds, letting the shell's ssh wrapper clean up
and reconnect. ~/.ssh/config is read first and wins, so per-host
overrides still apply.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Fail closed when ssh -G cannot resolve the effective config

An unresolvable configuration could hide a RemoteCommand, so treat it
as non-interactive rather than reconnectable. Also strengthen the
tests from Copilot review: assert the complete disarm sequence, and
verify on a real interactive pty that Ctrl-C during a retry attempt
kills the reconnect loop itself, not just the in-flight attempt.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Tolerate the explicit RemoteCommand none when probing ssh -G

The literal "none" is how ssh_config cancels a configured
RemoteCommand, and some OpenSSH versions emit it even when unset, which
would have silently disabled reconnecting entirely. Treat it as no
remote command while still failing closed on real ones and unresolvable
configs, and make the fake ssh -G emit the "none" form so the behavior
tests cover it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

This commit is contained in:

David Heinemeier Hansson

2026-08-09 19:15:21 +02:00

committed by

GitHub

co-authored by

Claude Fable 5

parent 9d61915b2e

commit 6ddc39520d

5 changed files with 280 additions and 0 deletions

									
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				echo "Detect dropped SSH connections quickly instead of leaving terminals hung"

				conf="/etc/ssh/ssh_config.d/20-omarchy-keepalive.conf"

				if [[ ! -f $conf ]]; then

				  sudo install -d -m 755 /etc/ssh/ssh_config.d

				  # An explicit mode so a restrictive user umask cannot leave the root-owned

				  # drop-in unreadable to the unprivileged ssh client.

				  sudo tee "$conf" >/dev/null <<'EOF'

				# Omarchy: notice dropped connections quickly instead of hanging until TCP

				# times out. Settings in ~/.ssh/config take precedence over these defaults.

				Host *

				  ServerAliveInterval 15

				  ServerAliveCountMax 3

				  ConnectTimeout 10

				EOF

				  sudo chmod 644 "$conf"

				fi