comment

gc is an operator, so it composes with every motion and text object the grammar has:


`gcc`	the current line
`gc3j`	this line and the three below
`gcap`	the paragraph
`gci{`	the inside of a block
`gc` (Visual)	the selection
`3gcc`	three lines

Run it again on the same range to uncomment.

Getting it

It ships with lattice and is enabled by default — nothing to install, no toolchain, works offline.

It contributes the minor mode comment-mode, and the loader registers comment.enabled as the switch for it:

:set comment.enabled=false


Seams it plugs into	`grammar`, `modes`, `config`, `help`
Capabilities it asks for	`grammar:chord`

What "toggle" means exactly

A range uncomments only if every non-blank line in it is already commented. A mixed range comments, rather than inverting each line — per-line toggling turns a partly-commented selection inside out, which is never the intent.
The leader goes at the range's shallowest indent, not at column 0, so relative indentation survives the round trip.
Blank lines are skipped. A commented blank line is trailing whitespace with extra steps.

Comment then uncomment returns the buffer to exactly what it was.

Languages

The leader is chosen by file extension:

Leader	Extensions
`//`	`rs` `c` `h` `cpp` `hpp` `go` `java` `js` `jsx` `ts` `tsx` `wit`
`#`	`py` `rb` `sh` `bash` `yaml` `yml` `toml`
`--`	`sql` `lua`

An extension not in that list has no comment syntax here, and gc says so rather than guessing. CSS and Markdown are deliberately absent: /* and <!-- are block delimiters, and one per line would write syntax errors into your file.

Options


`comment.enabled`	Turn the plugin off. Takes `gc` with it — the chord belongs to `comment-mode`, not to the builtin grammar.
`comment.leader-space`	Insert a space after the leader (`// code`, not `//code`). Default on.

How it is put together

Worth reading if you are writing a plugin, because comment is the first one to contribute an operator rather than actions or motions.

The operator is registered through the grammar seam and declares its own chord:

grammar::register_operator(
    "comment-toggle",
    "toggle line comments over the operated range",
    &OperatorSpec {
        repeatable: true,
        chord: Some("gc".to_string()),
        doubled: Some("c".to_string()),   // the TRAILING key: `gcc`
        ..
    },
    CB_TOGGLE,
);

The host binds that into the universal operator-pending layer, so gc gets motion targets, the doubled form, text-object pendings and find-char pendings — the same surface a builtin operator has. That binding is a declared capability, grammar:chord in plugin.toml: claiming keys in the grammar every buffer shares is the most user-visible power a plugin can take, so it is requested rather than assumed. Withheld, comment-toggle still registers and remains reachable by name; only the chord stops working.

Everything lives on comment-mode, a global minor mode — every document buffer, and deliberately not universal, which would also put gc in *messages*, the file tree and help popups.

See plugins for the seams, and :describe-plugin comment for what this one contributed.