+ssh: terminfo install fails on macOS when $TMPDIR is longer than 51 characters (ControlPath too long)

[adamklein]

Issue Description

On macOS, +ssh can't install terminfo when $TMPDIR is longer than 51 characters. Nix dev shells, here direnv's use flake, set TMPDIR=$TMPDIR/nix-shell.XXXXXX (65 characters). From those shells, every ssh fails the install, and the host is never cached.

installRemoteTerminfo passes -o ControlPath=$TMPDIR/ghostty-ssh-<22 random chars>. ssh binds a temporary socket at that path plus .<16 random chars>, which comes to len($TMPDIR) + 52 bytes. macOS sun_path holds 103 bytes plus the NUL. The default $TMPDIR is 48 characters, which leaves 3 bytes spare.

Related: #14875 changes this ControlPath only when the user already has one configured, so this bug would remain for everyone else.

Workaround: shorten TMPDIR for the call (TMPDIR=/tmp ssh host), or remove ssh-terminfo from shell-integration-features.

AI disclosure: Claude Code traced the cause in the 1.4.0 source, ran the repro on my machine, and drafted this report. I reviewed and edited it.

Expected Behavior

Terminfo installs regardless of the length of $TMPDIR.

Actual Behavior

ssh can't create the control socket, so the install fails, and the session falls back to TERM=xterm-256color. Every later connection tries again and fails the same way.

Reproduction Steps

Any reachable host works. Run in bash or zsh:

d51=/tmp/$(printf 'a%.0s' {1..46})   # 51 chars
d52=${d51}a                          # 52 chars
mkdir -p "$d51" "$d52"
TMPDIR=$d51 ghostty +ssh --verbose --cache=false -- user@host true   # installs
TMPDIR=$d52 ghostty +ssh --verbose --cache=false -- user@host true   # InstallFailed

Ghostty Logs

unix_listener: path "/var/folders/ng/5py4pcld4yjfc2qtmzwdvbm00000gn/T/nix-shell.uQe2xt/ghostty-ssh-MQ3W8QGg_r1ENTaewCzvJQ.ovOumWCgYupNjXwC" too long for Unix domain socket
Warning: failed to install terminfo: InstallFailed

Ghostty Version

Ghostty 1.4.0

Version
  - version: 1.4.0
  - channel: stable
Build Config
  - Zig version   : 0.17.0
  - build mode    : .fast
  - app runtime   : .none
  - font engine   : .coretext
  - renderer      : renderer.generic.Renderer(renderer.Metal)
  - libxev        : kqueue

OS Version Information

macOS 15.7.3 (24G419)

(Linux only) Display Server

None

(Linux only) Desktop Environment/Window Manager

No response

Minimal Ghostty Configuration

# None: the repro calls `ghostty +ssh` directly.
# Through shell integration it needs:
shell-integration-features = ssh-terminfo

Additional Relevant Configuration

No response

I acknowledge that:

• I have reviewed the FAQ and confirm that my issue is NOT among them.
• I have searched the Ghostty documentation and confirm there doesn't exist a configuration option that solves my issue.
• I have searched the Ghostty repository (both open and closed Discussions and Issues) and confirm this is not a duplicate of an existing issue or discussion.
• I have checked the "Preview" tab on all text fields to ensure that everything looks right, and have wrapped all configuration and code in code blocks with a group of three backticks (```) on separate lines.