One flat CFG production, lhs -> rhs, produced by Grammar.LRTable.Desugar from a grammar's PEG-shaped IR (Seq/Choice/Star/Plus/Opt/Rep each desugar to one or more of these; Choice in particular maps directly onto "more than one production for the same lhs" -- the natural CFG shape ordered PEG choice already resembles, minus the ordering).

captures describes how to rebuild the exact same raw-capture shape Ichor.Actions expects ({:token,...}/{:rule,...}/{:text,...}) at reduce time, one entry per captured RHS position:

• {index, name, :token} -- RHS position index is a bare (or explicitly named) reference to a token; becomes {:token, terminal_name, text} (or the token's own capture override, exactly like every other backend).
• {index, name, :rule} -- same, but index names a rule; becomes {:rule, nonterminal_name, child_captures}.
• {index, name, :text} -- index is a captured composite sub-expression (anything other than a direct bare RuleRef -- x:(a b), x:"lit", x:choice, ...), desugared into its own helper nonterminal; becomes {:text, span_text}, the matched token text from that position's start to its end, exactly like RuleCompiler.leaf/4's unconditional fallback for the same shape.
• {index, nil, :splice} -- index is a helper nonterminal standing in for Star/Plus/Rep/Opt (or the left-recursive accumulator half of one) -- its own already-built captures map is merged key-by-key into this production's, list-accumulating exactly like Ichor.Actions' merge_capture/3 does for a capture repeated inside an ordinary PEG */+. This is what makes a repeated capture end up as a list in the enclosing rule's own capture map, rather than trapped one level down under a compiler-generated helper name nothing in Ichor.Actions knows about.

An uncaptured RHS position (an anonymous auto-promoted literal token, the grammar's own spliced @skip token, or anything inside a :text-discarded span) has no entry in captures at all -- it contributes nothing to the built map, same as an anonymous token contributes no implicit self-capture on any other backend.