Spell checking

Mitos can spell-check documents and surface misspellings as diagnostics. Corrections and “add to dictionary” are offered as code actions, alongside any from language servers.

Spell checking is opt-in. Mitos will use tree-sitter to check only requested regions of a language to avoid noisy diagnostics for keywords. Multiple dictionaries may be configured at once. A word is accepted if any configured dictionary allows it.

Enabling

There are several ways to turn spell checking on:

1. Per buffer, with the command:

   :set-spelling-language <language>
   

   Pass several languages to check against all of them (:set-spelling-language en_US en_GB), or off to disable checking for the buffer. With no argument it reports the current language(s). This choice overrides the settings below and persists across config reloads for that buffer.

2. Per path, with an .editorconfig spelling_language key:

   [*.md]
   spelling_language = en_US
   

3. Per language, in languages.toml (see Languages):

   [[language]]
   name = "markdown"
   spelling.languages = ["en_US"]
   

4. Globally, in config.toml under [editor.spelling]:

   [editor.spelling]
   languages = ["en_US"]
   

Scope

What gets checked is controlled per language by a tree-sitter spellcheck.scm query: a node captured @spell is checked, and @nospell excludes part of one. Most languages inject a shared comment grammar, so their comments are checked with no language-specific query. The bundled queries also cover:

Python docstrings are treated as prose; examples and markup inside them are not parsed separately. reStructuredText directive bodies are left unchecked because their syntax nodes do not distinguish prose from code.

Coverage depends on the queries present in your runtime directories. Strings and identifiers are checked only where a language’s query opts them in. With syntax parsing, text outside @spell captures is left unchecked. Plain text and files without a syntax tree are checked in full.

See Adding spellcheck queries to extend coverage to a new language.

Navigating and selecting findings

Use ]s to select the next spelling finding and [s to select the previous one. These commands skip other diagnostics, support counts such as 3]s, and stop at the first or last finding without wrapping. In select mode they extend the selection; with multiple cursors each cursor moves independently.

The s textobject selects the diagnosed word under the cursor with mis or mas. Use mIs or mAs to select all spelling findings fully contained in the current selection. Both inside and around variants use the finding’s exact range.

Correcting findings

Move onto a misspelled word (or select it with ]s, [s, or mis) and press Space-a to open code actions. Choose a Replace ... action and press Enter to replace the whole word. Press u to undo the correction, or Escape to dismiss the menu without changing the text.

Spelling actions work without a language server. With multiple selections, the menu offers corrections for findings overlapping the primary selection. The same menu offers Add ... to dictionary to accept a word permanently.

Ignoring a word for this session

Choose Ignore 'word' for this session (language) from Space-a to suppress that word until Mitos exits. Matching is case-insensitive and applies to the whole word, including in other open buffers and buffers opened later that use the chosen dictionary. Other misspellings continue to be checked.

With multiple dictionaries, choose the language the ignore should apply to. A buffer ignores the word if any of its configured dictionaries has a session ignore for it. The ignore survives edits, configuration reloads, and toggling spell checking off and back on. It does not change the document or write to your personal dictionary or configuration files.

Ignoring a word permanently

Choose Ignore 'word' forever (language) from Space-a to keep ignoring it after restarting Mitos, across projects using that dictionary. Matching is case-insensitive and applies to the whole word, just like a session ignore.

Persistent ignores are stored as UTF-8 text, one word per line, in <config>/spelling/<language>.ignore, for example ~/.config/mitos/spelling/en_US.ignore on Linux. They are loaded when the dictionary is first used. Remove a word from that file and restart Mitos to check it again, or add words there by hand.

Ignore forever suppresses findings without adding words to the dictionary’s suggestion vocabulary. Use Add ... to dictionary when you also want the word available as a correction suggestion. A failed save reports an error and leaves the word’s checking behavior unchanged.

Dictionaries

Dictionaries are Hunspell .aff/.dic pairs loaded from dictionaries/<language>/<language>.{aff,dic} in the runtime directories. ms --health lists those directories.

Mitos bundles only en_US. To add another language, drop its Hunspell files into a runtime directory, named after the language code you reference in the config. For example, for de_DE:

~/.config/mitos/runtime/dictionaries/de_DE/de_DE.aff
~/.config/mitos/runtime/dictionaries/de_DE/de_DE.dic

Hunspell dictionaries for most languages are distributed with LibreOffice and by the various aspell/Hunspell projects.

Personal dictionary

The “Add to dictionary” code action accepts a word permanently. It is appended to a personal dictionary, one word per line, under Mitos’s state directory:

<state>/dictionaries/<language>.txt

(<state> is e.g. ~/.local/state/mitos on Linux.) The file is namespaced per language, so a word added for one language is not accepted in another. You can edit it by hand; entries are loaded the next time that language’s dictionary is read.

Tuning

Spell checking produces false positives on names, jargon, and code-like tokens. URLs and email addresses are skipped automatically. Beyond that, three knobs (settable globally under [editor.spelling] and per language in languages.toml) reduce noise:

When both global and per-language settings are present, languages and min-word-length are replaced by the language’s value, while words and ignore-regexes are added to the global lists. See [editor.spelling] for the full reference.