An evidence card is a structured note tied to one original source and one precise locator. It records what was studied, what the source supports, the evidence type, the result, and the limitation that keeps the claim in bounds.
It is not a quote collection. It is not a scorecard for making a source agree with a preselected idea. And it is not a cross-source synthesis.
That distinction is useful because a vivid result can look more general than it is. A source may concern stated sharing rather than observed sharing; a product recommendation rather than sustained adoption; a particular platform interface rather than a durable human mechanism.
The cards keep those details available until there is enough verified evidence to compare sources responsibly.