diff --git a/docs/design/INDEX.md b/docs/design/INDEX.md
index 190fa24..9257ef0 100644
--- a/docs/design/INDEX.md
+++ b/docs/design/INDEX.md
@@ -306,9 +306,22 @@ completion, not a contract change. A strategy composite is simply the K=1 case
 they live at the blueprint boundary and in render (`[out:<name>]` markers, #13)
 but are dropped at lowering — `ItemLowering::Composite.output` is `Vec<(usize,
 usize)>`, raw index pairs only, so the compilat is name-free (verified: the
-compiled-view render stayed bit-identical across this change). Input-role and
-param **names** at the same boundary remain index-only pending #41 (the legibility
-sibling that depends on this cycle).
+compiled-view render stayed bit-identical across this change).
+**Realization (cycle 0019 — name the composite boundary, #41).** The same
+named-projection shape now covers the other two boundary edge-kinds, so **all
+three** are uniform: `input_roles` is a `Vec<Role { name, targets }>` (was a bare
+`Vec<Vec<Target>>`) and a composite carries `params: Vec<ParamAlias { name, node,
+slot }>`, alongside `output: Vec<OutField>`. Each is an ordered, positionally-indexed
+**named projection** of interior handles. Param aliasing is a **pure naming overlay**,
+not curation: `param_space()` relabels an aliased slot's surface name **in place** —
+slot order, arity, and kinds are unchanged, so the sweep surface is identical and the
+`param_space_mirrors_compiled_flat_node_param_order` anchor stays green. Like the
+output names, role and param **names** are **non-load-bearing** (C23): they live at
+the blueprint boundary and in render (`[in:<name>]` / `[param:<name>]` markers) but
+are dropped at lowering — the compilat is wired by raw index and a dangling alias is
+rejected at compile (`BadInteriorIndex`), not silently lowered. The full composite
+boundary signature (named inputs, params, multi-outputs) is now legible without
+changing the compilat.
 
 ### C10 — Strategy output is an intent/exposure stream; position management is a decoupled derived layer; brokers are downstream nodes
 **Guarantee.** A strategy's primary, backtestable output is **not** an equity