Constant NODE_COUNT_LIMIT 

pub const NODE_COUNT_LIMIT: u64 = github_graphql_node_count::NODE_LIMIT; // 500_000u64

The most nodes any one document this source sends may be asked to return.

GitHub’s own published per-query ceiling, taken from github_graphql_node_count::NODE_LIMIT rather than written out again here, so this workspace cannot hold a stale copy of somebody else’s number. A query above it is refused before it is executed, whoever is asking and whatever board they are asking about — so this is a bound on the documents rather than a budget that runs out.

This is nodeCount, the maximum number of nodes one query may return. It is not cost, the rate-limit points a call spends against an hourly allowance shared by everything the credential does. Two numbers, two limits; nothing here is about the second. The module section on the three ways this source reaches an item says how the count is arrived at, and which of the page sizes below decide it.