The range
A byte range on its own says nothing. Resolved against the file's own metadata, it says exactly which columns or tiles it touches — and that is the whole basis for deciding whether it may be served.
Ranges a reader would really ask for
What that range exposes
Regions it covers
Where it lands
The structure itself, as the policy sees it
The file's own metadata
Parsed once from the end the format keeps it. Everything above is derived from this and nothing else.
Layout
The policy
CQL2 over the regions a range resolves to. Pick one, or edit it — it is validated as you type, and every property is checked against the schema.
Who is asking
How the gate answers a request covering withheld bytes
Query it
The gate is at … — an ordinary URL.
DuckDB is not told anything about the policy; it just reads.