Search Bluesky posts by keyword/query using app.bsky.feed.searchPosts, with sort order, filters, and cursor pagination.

Documented steps

1. GET $HOST/xrpc/app.bsky.feed.searchPosts?q=<query> where q (required) is a search query string; syntax is unspecified but the API reference recommends Lucene query syntax as a convention.
2. Optionally add sort=top|latest (default latest) to rank results by engagement ('top') or recency ('latest').
3. Optionally add limit=<1-100, default 25> and cursor=<token from a previous response> for pagination; the response includes an optional 'cursor' field to pass into the next request, plus an optional 'hitsTotal' integer.
4. Optional filters: author=<did-or-handle> (handles are resolved to DID server-side before querying), mentions=<did-or-handle> (matches only rich-text facet mentions, not plain @-text), tag=<one or more tags, ANDed together, no leading #, maxLength 640 each>, url=<filter to posts linking this URL>, domain=<filter to posts linking this hostname>, lang=<language code>.
5. Optional time-range filters since=<datetime or YYYY-MM-DD> and until=<datetime or YYYY-MM-DD> - both filter on the server's 'sortAt' timestamp (which may differ from the post's own createdAt), inclusive for since and exclusive for until.
6. Parse the response's 'posts' array (of postView objects); continue paginating using 'cursor' until it is omitted from the response.
7. Send the request with an Authorization: Bearer <accessJwt> header pointed at your own PDS/entryway if you need guaranteed access - the endpoint's own description warns 'this API endpoint may require authentication (eg, not public) for some service providers and implementations', i.e. unlike some other app.bsky reads, public unauthenticated access is not guaranteed by every provider.