diff --git a/docs/design/INDEX.md b/docs/design/INDEX.md
index 488e108..a04a777 100644
--- a/docs/design/INDEX.md
+++ b/docs/design/INDEX.md
@@ -245,6 +245,24 @@ so a graph render (C9 graph-as-data, #13) disambiguates identical node types and
 surfaces a mis-wiring. Like `FieldSpec.name`, it is an informative debug symbol,
 not part of the C8 dataflow contract — adding it changes no run behaviour.
 
+**Realization (cycle 0015 — param declaration).** The tunable-parameter half of
+this contract is now realized: a node declares its knobs in `schema()` as
+`params: Vec<ParamSpec>` (`ParamSpec { name: String, kind: ScalarKind }`), and
+`Blueprint::param_space()` aggregates them into one flat, path-qualified list — a
+read-only projection of the graph-as-data (C9), mirroring the inline order
+(C19/C23) so a param's slot matches the later flat-node order. Two refinements to
+the guarantee's "typed, with ranges": (1) the declaration carries `name` + `kind`
+only — the **search-range is the run's, not the node's** (which subset / grid a
+sweep covers is an experiment axis, #32/C20; the node declares the knob's existence
+and type, never its search interval). (2) Identity is **positional** (the slot,
+C23 "by index, not name"); the path-qualified `name` is a non-load-bearing debug
+symbol (like `FieldSpec.name`) — same-type siblings in one composite share a name,
+uniqueness is at the slot. A vector knob (`LinComb.weights`) expands to `N` flat
+`weights[i]` entries, `N` topology-fixed (C19). Permitted kinds are `i64`/`f64`/
+`bool` (a `timestamp` knob is a structural axis, C20, never a numeric sweep param).
+Binding a value to a slot (#31) and enumerating a sweep (#32) are the deferred next
+layers.
+
 ### C9 — Fractal, acyclic composition
 **Guarantee.** A composite is itself a `Node` that wires a sub-graph and exposes
 one output; signal, combined signal, and (with execution) strategy are all the
@@ -662,8 +680,9 @@ blueprint → inline / compile → flat instance — is the load-bearing substra
 **first**; the optimisation passes (intra-compilat CSE/DCE, sweep-invariant
 hoisting) are **deferred**, behaviour-preserving follow-on work, each gated by a
 "compilat with pass ≡ compilat without pass, bit-identical run" test (C1). The
-sweep-level pass further presupposes per-node param declarations (C8 — *deliberately
-not in the schema yet*) and the sweep orchestration itself (C12/C21).
+sweep-level pass further presupposes per-node param declarations (C8 — landed in
+cycle 0015 as `name`+`kind`; the swept *range* still pending #32/C20) and the sweep
+orchestration itself (C12/C21).
 
 ---