tern-ssh

An ssh host manager that runs as a Tern pane. It lists the hosts of an ssh config, connects to them, and adds, edits and removes hosts without leaving Tern.

Inside Tern the list, the host details and the add/edit form are native elements drawn through the Tern Surface Protocol (with the Go SDK); in any other terminal the same program prints the hosts as plain text.

The details card shows on i; the list is what opens by default.

Install

tern plugin install github.com/aancw/tern-ssh

If you want to clone the repo or manually install using go:

# clone the repo
git clone github.com/aancw/tern-ssh
make build           # bin/tern-ssh
make plugin-link     # use this checkout as the plugin, then: tern plugin reload
make plugin-install  # install a copy of it (--force to replace one)

# install via go install
go install github.com/aancw/tern-ssh@latest          

# reload the tern plugin                          
tern plugin reload

tern plugin list should show ternssh … window ready. A plugin listed as disabled is named in plugins_disabled in Tern's settings.json; remove it there or toggle it in Preferences → Plugins.

Palette rows and chords

Two rows, in the SSH palette group, one per placement, because a plugin command cannot see which chord ran it, so the placement cannot be a modifier of one row:

Row	Action id	What it does	Default chord
SSH hosts	plugin.ternssh.open	opens the manager in a new tab	none
SSH hosts split	plugin.ternssh.split	opens it in a split of the focused pane	cmd+shift+h

One chord runs one action, so only split carries a default. Bind what you use in settings.json; a chord Tern's own keymap already takes is dropped with a plugin bind left out warning in the log:

{ "keybinds": {
	"cmd+shift+h": "plugin.ternssh.split",
	"cmd+alt+shift+t": "plugin.ternssh.open"
} }

A clicked ssh://user@host:port link opens a session for that host in a split of the pane it was clicked in.

Keys

Key	What it does
enter	connect in this pane; the manager returns when ssh ends
a	add a host
e	edit the selected host
d	remove the selected host (with a y/n prompt)
i	show or hide the selected host's details
/	filter the list; esc clears
j k g G	move the cursor
r	read the config file again
q	quit

A host whose block sets no User asks which login name to use before it connects. The name is passed to ssh with -l; leaving the prompt empty logs in as the local user, which is what ssh does with no User at all.

In the form: tab and shift+tab move between fields, enter saves, esc cancels, ctrl+u clears the field.

The config file

$TERN_SSH_CONFIG, or ~/.ssh/config with --config PATH. A missing file is fine: the first host you add creates it.

Writes are surgical. Adding appends one block; editing rewrites only the lines of that block, keeping its comments and the directives the form does not manage (ProxyCommand, forwarding, and so on); removing drops that block alone. Nothing else in the file changes, and the file keeps its permissions.

Editing the alias rewrites the block's Host line, so a host can be renamed. A name already in the file is refused, and the form says so.

Blocks the manager writes carry a # tern-ssh marker above them.

How it talks to Tern

• Connections run tern ssh <alias>, Tern's own ssh, so a host that lacks Tern's terminfo entry still gets a working terminal. With a --config other than ssh's default, -F <file> is passed too, so the alias resolves the way the manager shows it.
• enter gives this pane to ssh: the protocol session is closed first (which restores the terminal and stops the input reader, so no keystrokes are stolen) and the pane is handed over with exec. When ssh ends, the pane runs the manager again, so it comes back.
• That session runs in the manager's own pane, never in another one: a pane cannot reliably open a block beside itself, because tern split resolves the window from TERN_WINDOW_KEY and Tern does not always set it. To keep the manager on screen while a session runs, open the session from another pane, or run tern split yourself.

TODO

• Connect in a block beside the manager, or in a new tab. Parked as park: comments in internal/app/app.go (the s and t keys) and internal/app/connect.go (spawn). Blocked because a pane cannot say which window it belongs to: tern split reads TERN_WINDOW_KEY, Tern does not always set it in a pane, so the CLI falls back to the first window and the block can land next to another window's pane. Uncommenting the two blocks is not enough; the fix has to find the window reliably first, either from a value the pane can read or by letting the plugin's window half open the block from a request the manager leaves behind.

Limits

• Only the file itself is read. Include directives are not followed, and Match blocks are left alone.
• Blocks whose patterns are not literal (Host *, Host *.example.com) are not listed. Their options still show up as the resolved values of the hosts they apply to.
• Port, HostName, User and IdentityFile values are shown as written; %h-style tokens and a leading ~ in IdentityFile are not expanded.
• The form manages HostName, User, Port, IdentityFile and ProxyJump; an alias keeps one Host line.

Layout

Path	Holds
main.go	the command line: the manager, and list, add, edit, remove, connect
internal/sshconf	reading, resolving and editing the ssh config
internal/app	the Tern pane: state, keys, views, plain-text fallback
plugin.toml, window.luau	the Tern plugin package; it sits at the root, so the repository is the package

Development

make build           # bin/tern-ssh
make test            # the sshconf tests
make plugin-link     # use this checkout as the plugin, then: tern plugin reload
make plugin-install  # install a copy of it (--force to replace one)

LICENSE: MIT.