Spell

bridge.spell checks prose text against the OS system dictionary (NSSpellChecker on macOS) and returns misspelling spans for the markdown editor's underline decorations.

Adapter support

bridge.spell.isSupported() has no Capabilities flag — it is a runtime probe only, like bridge.fileSearch.isSupported():

• Tauri macOS desktop — checks text against the account's system dictionary and user-added words.

• Mock adapter — deterministic in-memory fixture for renderer tests and isolated preview fixtures. It never touches an OS dictionary.

• REST, browser production, iOS, and other Tauri platforms — report unsupported. They never forward spell-check requests to an HTTP endpoint or another engine.

check never throws on any adapter, including when unsupported — it is called from a timer-driven editor plugin that cannot afford to crash the debounce loop.

Bridge contract

interface SpellRange {
  start: number;
  length: number;
}

interface SpellAPI {
  isSupported(): Promise<boolean>;
  check(texts: string[]): Promise<SpellRange[][]>;
  suggest(word: string): Promise<string[]>;
  learn(word: string): Promise<void>;
  ignore(word: string): Promise<void>;
}

function createUnsupportedSpell(): SpellAPI;

check takes one paragraph-sized prose segment per array entry and returns one SpellRange[] per input segment, in input order. start/length are UTF-16 code units — the same unit JS string indexing and CodeMirror 6 offsets use, so no conversion is needed before turning a range into a decoration.

suggest returns up to 5 correction suggestions for a single word, best-first. learn adds a word to the OS user dictionary (persists across sessions and other apps on the same machine). ignore suppresses a word for the current app session only, scoped to one spell-document tag on the Tauri adapter — it does not persist and does not affect the OS user dictionary.

createUnsupportedSpell() is the shared stub behind RestAdapter: isSupported() resolves false, check(texts) resolves texts.map(() => []), suggest resolves [], and learn/ignore resolve without effect.

Mock adapter fixture

createMockSpell(options?: MockSpellOptions) ships a fixed default word list (teh→the, recieve→receive, definately→definitely, wierd→weird, mesage→message, spelings→spellings), matched case-insensitively by tokenizing each segment on /[A-Za-z']+/. options.words replaces the fixture; options.supported overrides the default navigator.platform Mac sniff (copied from the mock fileSearch.isSupported disambiguation of real macOS vs iPadOS via maxTouchPoints).

learn/ignore are tracked in an in-memory set scoped to that createMockSpell() call, so subsequent check calls on the same instance stop flagging a learned or ignored word — this is observable directly in tests without a fake IPC layer.

Related

See Spellcheck for the full feature: the Rust engine, the CodeMirror extension, the context menu, settings, and the design decisions behind the contract above.