Context: commands, editor, files, events

The context object passed to activate() exposes these APIs, each gated by the capability (or capabilities) declared in the manifest. Signatures below are taken verbatim from src/plugins/types.ts (published as examples/plugins/plugin-api.d.ts).

context.commands (requires commands)

interface CommandRegisterOptions {
  paletteVisible?: boolean;
  title?: string;
}

register(
  id: string,
  handler: (...args: unknown[]) => unknown,
  opts?: CommandRegisterOptions,
): Disposable;

execute(id: string, ...args: unknown[]): Promise<unknown>;

Registering a command with opts.paletteVisible === true or any opts.title surfaces it in the Command Palette — see Command Palette integration.

context.editor (requires editor or editor:readonly)

getContent(): string;                       // plain text, not Markdown/HTML
setContent(content: string): void;          // editor only — throws under editor:readonly
getSelection(): { from: number; to: number; text: string };
insertText(text: string): void;             // editor only — throws under editor:readonly

getContent() returns the document’s plain text (editor.getText() internally) — not Markdown source and not HTML.

context.files (requires files or files:readonly)

readFile(path: string): Promise<string>;
writeFile(path: string, content: string): Promise<void>;  // files only — throws under files:readonly
listDir(path: string): Promise<string[]>;                  // resolves to entry names, not full paths

context.events (requires events)

on(event: string, handler: (...args: unknown[]) => void): Disposable;
emit(event: string, ...args: unknown[]): void;

The only events the host currently emits are "editor:ready", "file:open", and "file:save" (the PluginEventName union type). There is no per-keystroke or live document-change event yet — if you need to react to edits, recompute on editor:ready/file:open/file:save instead of polling or expecting a "editor:change"-style event (it does not exist). See the word-count example for the pattern.

"file:open" fires once the opened file’s content is actually loaded into the editor — not at the moment the tab opens — so for markdown files ctx.editor.getContent() reads the right document inside the handler. It also fires when switching to a tab that was already open (not just on first open). For non-markdown files the event still fires after the source editor loads, but ctx.editor wraps the ProseMirror (markdown) editor, so getContent() does not reflect code-file content.