Concepts

The mental model behind the API — why things work the way they do, and the honest edges. Read these when a method surprises you or when you want to predict behavior instead of trial-and-erroring it.

• The spatial model — everything is boxes; how directional navigation, anchors, until=, and within= actually resolve.
• How text becomes elements — chars → words → elements, tolerance settings, and why text:contains() can miss a phrase that extract_text() shows.
• Exclusions — read-time views, not deletions; when they bind, what honors them, when not to use them.
• Selectors — the grammar, how it differs from CSS, and the region-type vocabulary that layout engines produce.
• Tables, a decision guide — the recovery ladder from bordered tables down to scanned ones.
• Engines and models — what downloads what and how big, local vs remote VLMs, and the privacy contract for set_default_client().