diff --git a/docs/authoring-guide.md b/docs/authoring-guide.md
index 8f0fd47..d1d58a5 100644
--- a/docs/authoring-guide.md
+++ b/docs/authoring-guide.md
@@ -221,14 +221,15 @@ $ aura graph build < smacross.json > blueprint.json
 Nodes are referenced by an **identifier** (given by `add`, see below); ports
 are dotted `<identifier>.<port>` on both sides of a wire.
 
-### The nine ops
+### The ten ops
 
 | op | JSON shape | does |
 |---|---|---|
 | `doc` | `{"op":"doc","text":<str>}` | declare the composite's one-line meaning (C29) — the op-script twin of the Rust builder's `.doc(...)`. Required before `aura graph register` accepts the product (the store refuses a doc-less composite); at most one per script (a second refuses: `a doc op may appear at most once`). The text is gated: empty or merely restating the composite's name refuses at register. |
 | `source` | `{"op":"source","role":<str>,"kind":<ScalarKind>}` | reserve a bound root **source** role of `kind` — a real input the harness feeds (e.g. `"price"`). |
-| `input` | `{"op":"input","role":<str>}` | reserve an open root **input** role (kind inferred from the slots it feeds) — for a fragment meant to be wired by an *enclosing* graph. A standalone document built with `aura graph build` finalizes as a closed root, so an `input` role that is never bound refuses at the end: `finalize: root input role <name> is unbound`. |
+| `input` | `{"op":"input","role":<str>}` | reserve an open root **input** role (kind inferred from the slots it feeds) — the formal parameter of an **open pattern**, a fragment meant to be wired by an *enclosing* graph. An open pattern builds and registers like any blueprint; only *running* it standalone refuses (bootstrap's unbound-root-role gate — there is no enclosing graph to wire it). |
 | `add` | `{"op":"add","type":<TypeId>,"name":<str>?,"bind":{<param>:<Scalar>}?}` | instantiate a node of a type in the closed vocabulary (`aura graph introspect --vocabulary`) — see §0 below for how a type gets into that vocabulary in the first place. `name` becomes the node's identifier for later ops (default: the type's own lowercase label — two unnamed nodes of the same type then collide). `bind` sets zero or more of its params. |
+| `use` | `{"op":"use","ref":{"content_id":<id-or-prefix>}\|{"name":<label>},"name":<str>?,"bind":{<path>:<Scalar>}?}` | splice a **registered blueprint** into the graph as a nested composite under an instance identifier (`name`; default: the stored composite's own name). The ref resolves by content id (full or unique prefix) or by a register-time label; `graph build` echoes every resolution (`aura: note: use "…": … -> <id>`) so the exact id can be pinned. The instance's open input roles wire as `<instance>.<role>`, its outputs as `<instance>.<field>`; its open params surface path-qualified (`<instance>.<node>.<param>`), sweepable (ganging an instance's params is not yet supported — the `gang` op refuses a composite instance's member path). A doc-less stored source refuses at the op (C29). The emitted blueprint contains the subgraph *inline* — no reference survives into the artifact. |
 | `feed` | `{"op":"feed","role":<str>,"into":[<port>, …]}` | fan a previously-declared role into one or more interior input slots, all-or-nothing (a failing target leaves none of the batch wired). |
 | `connect` | `{"op":"connect","from":<port>,"to":<port>}` | wire one interior output field to one interior input slot. A `connect` that would close a dataflow cycle is rejected immediately — the only legal feedback path is an explicit delay/state node (domain invariant 5). |
 | `expose` | `{"op":"expose","from":<port>,"as":<str>}` | promote an interior output field to a boundary output under the alias `as` — a real *alias* (a terminal boundary name, not a referenceable identifier like `add`'s `name`). Together with `tap`, one of the two ops whose `as` key is a terminal name rather than an identifier. |
@@ -405,6 +406,13 @@ registered blueprint 597d719b7ac607158cda3e68cd497387620397a5e93087e23da512876da
 The printed content id is the address a campaign document's `strategies[].ref`
 points at (§3).
 
+`graph register <file> --name <label>` additionally records a **blueprint
+label** — a legible, re-pointable handle for the `use` op's `{"name":…}`
+ref form (re-registering under the same label repoints it; the echo names
+the previous target). `aura graph introspect --registered` lists the
+labels with their id prefix and root doc line — the discovery surface for
+what `use` can reference.
+
 ## 2. Process documents — a validation methodology (role 5)
 
 A process document is a named, versionable pipeline of **std stage blocks**
diff --git a/docs/design/contracts/c24-blueprint-data.md b/docs/design/contracts/c24-blueprint-data.md
index d377c92..170b129 100644
--- a/docs/design/contracts/c24-blueprint-data.md
+++ b/docs/design/contracts/c24-blueprint-data.md
@@ -144,17 +144,38 @@ per-op checks — name resolution, edge kind-match (`edge_kind_check`), the doub
 arm, param bind, and acyclicity (a `connect` that would close a cycle is rejected
 eagerly at the closing op, `GraphSession::closes_cycle`, #161) — and **holistic**
 finalize checks — wiring totality (`validate_wiring`), param-namespace injectivity
-(`check_param_namespace_injective`), root-role boundness (`check_root_roles_bound`).
-Both cadences call the **same extracted predicates** — no second validator. The
-holistic faults read **by-identifier** (#162): `finish()` translates the
-index-carrying `CompileError`s (`UnconnectedPort` / `RoleKindMismatch` /
-`UnboundRootRole`) into by-identifier `OpError` variants while still *calling* the
-unchanged holistic gates. Build-free introspection answers over the closed vocabulary:
-`graph introspect --vocabulary | --node <T> | --unwired`. The engine `Op` stays
-serde-free; the wire DTO (`OpDoc`) is CLI-side (`aura-cli::graph_construct`).
-Acceptance: a graph built purely through the ops compiles identical (C1) to its
-Rust-built twin, an invalid op is rejected at the op naming the cause, introspection
-answers without a build.
+(`check_param_namespace_injective`). Both cadences call the **same extracted
+predicates** — no second validator. The holistic faults read **by-identifier**
+(#162): `finish()` translates the index-carrying `CompileError`s (`UnconnectedPort` /
+`RoleKindMismatch`) into by-identifier `OpError` variants while still *calling* the
+unchanged holistic gates. **Root-role boundness moved off this list (#317, open
+patterns):** `check_root_roles_bound` no longer runs in `finish()` — a `finish()`ed
+op-script may still carry an open (unbound) root role, declaring a reusable
+pattern's formal parameter; only `compile`/bootstrap (the runnability gate, not a
+construction gate) still call it, unchanged. Build-free introspection answers over
+the closed vocabulary: `graph introspect --vocabulary | --node <T> | --unwired`. The
+engine `Op` stays serde-free; the wire DTO (`OpDoc`) is CLI-side
+(`aura-cli::graph_construct`). Acceptance: a graph built purely through the ops
+compiles identical (C1) to its Rust-built twin, an invalid op is rejected at the op
+naming the cause, introspection answers without a build.
+
+**Registered-blueprint splice (#317).** The `use` op resolves a reference — a store
+content id, a unique content-id prefix (#302 semantics), or a registry **name
+label** (`graph register --name`, latest-wins, `aura-registry`'s
+`blueprint_names.jsonl` sidecar) — to a previously registered blueprint and
+splices it into the building graph as a nested `BlueprintNode::Composite` under an
+instance identifier. The **engine never resolves**: `GraphSession`/`replay` take a
+second injected closure, `subgraph: &dyn Fn(&str) -> Option<Composite>`, mirroring
+`vocab`'s closed-lookup posture exactly — this is the same enforcement-shift
+permission §"Enforcement shift" above already grants the node vocabulary, extended
+to registered-blueprint references. All store I/O — label/prefix resolution, the
+`get_blueprint` fetch, the C29 doc-gate re-walk over the fetched composite (before
+it ever reaches the session, so a doc-less fetched entry cannot enter a NEW
+composition), and the resolution echo — happens CLI-side, at DTO conversion, before
+replay; build-free introspection paths pass `&|_| None`. The echo
+(`aura: note: use "<instance>": <label-or-prefix> -> <full id>`) is the existing
+`aura: note:` benign-diagnostic marker (C14) — a new instance of the existing
+class, not a new one, so the exit-code/marker taxonomy is unchanged.
 
 **Invariant-5 lockstep.** The eager acyclicity gate is a *second* home of invariant 5
 alongside the bootstrap Kahn sort (`harness.rs`, `BootstrapError::Cycle`); the two
@@ -166,12 +187,14 @@ rejected at construction.
 
 The op-script is a JSON **array of ops**, each object internally tagged by `"op"`,
 replayed in order; nodes are referenced **by identifier**, ports as dotted
-`<identifier>.<port>`. The eight verbs:
+`<identifier>.<port>`. The ten verbs:
 
 - `source` — `{"op":"source","role":<str>,"kind":<ScalarKind>}` — declare a root
   source role producing a base column of `kind`.
 - `input` — `{"op":"input","role":<str>}` — declare a root input role (kind inferred
-  from the slots it feeds).
+  from the slots it feeds) — a reusable **pattern**'s formal parameter, left open
+  until an enclosing graph wires it (#317's open patterns): `finish()` accepts an
+  op-script that never binds it, only `compile`/bootstrap require it bound.
 - `add` — `{"op":"add","type":<TypeId>,"name":<str>?,"bind":{<param>:<Scalar>}?}` —
   add a node of compiled-in type identity `type`; **`name` is its identifier**
   (mirrors the builder's `.named(...)`; defaults to the lowercased type label, so
@@ -196,6 +219,19 @@ replayed in order; nodes are referenced **by identifier**, ports as dotted
   leave the sweepable param space and `as` replaces them; the bound or swept
   value fans out to every member at bootstrap. Members must share one scalar
   kind and stay open (un-bound).
+- `doc` — `{"op":"doc","text":<str>}` — declare the composite's one-line meaning
+  (C29, #316) — the op-script twin of the builder's `.doc(...)`; at most one per
+  script, a second is a fault (a declarative script carries no last-wins
+  ambiguity).
+- `use` — `{"op":"use","ref":{"content_id":<str>}|{"name":<str>},"name":<str>?,"bind":{<path>:<Scalar>}?}`
+  — splice a **registered** blueprint into the building graph as a nested
+  composite under an instance identifier (`name`, defaulting to the fetched
+  composite's own name); `bind` path-qualifies the spliced instance's params
+  (e.g. `"sma.length"`), applied after the splice (#317). An instance's open
+  input roles become its `<instance>.<role>` in-ports, its output boundary
+  aliases its `<instance>.<field>` out-fields — the same `Composite` arm every
+  other add/wiring path walks, not a new mechanism. See §"The construction
+  service" below for the resolution split.
 
 Value forms are the serialized representations: a `Scalar` bind value is the typed tag
 form `{"I64":2}` / `{"F64":0.5}` / `{"Bool":true}` / `{"Timestamp":<i64>}`, and `kind`
diff --git a/docs/design/contracts/c29-self-description.md b/docs/design/contracts/c29-self-description.md
index b33df88..a7855f6 100644
--- a/docs/design/contracts/c29-self-description.md
+++ b/docs/design/contracts/c29-self-description.md
@@ -27,13 +27,23 @@ cannot pass its short-name alibi
    restatement.
 3. **Register seam (data plane).** The registry's public `put_blueprint`
    parses the canonical bytes and requires a gate-passing doc on the root
-   composite and on every named nested composite — the gate guards the
-   store boundary itself, so the register verb, every register-then-run
+   composite and on **every** nested composite (the walk recurses
+   unconditionally — it does not stop at an unnamed one) — the gate guards
+   the store boundary itself, so the register verb, every register-then-run
    sugar path, and any future caller are gated by construction. The
    op-script vocabulary carries the `doc` op as the builder `.doc(...)`'s
    twin ([C25](c25-role-model.md): a closed, typed metadata construct).
    Process/campaign documents take an additive-optional top-level
    `description`, gated only when present (`DocFault::BadDescription`).
+4. **Use seam (data plane, construction-time, #317).** The `use`
+   construction op re-runs the SAME `gate_composite_docs` walk over a
+   blueprint FETCHED from the store, before it ever splices into a new
+   composition — a build-time gate on already-registered content, not a
+   second write-path check. A doc-less entry (reachable only through the
+   raw in-crate write survivor class, since `put_blueprint`'s own gate keeps
+   the store clean going forward) cannot enter a NEW composition this way,
+   but stays readable and runnable on its own — no retroactive invalidation,
+   the same discipline the Forbids clause states for the register seam.
 
 **Scope at this record's writing (#321).** The gate walks five
 vocabularies — process/campaign blocks, metrics, tap slots, tap folds, and
diff --git a/docs/glossary.md b/docs/glossary.md
index a095317..452c482 100644
--- a/docs/glossary.md
+++ b/docs/glossary.md
@@ -31,6 +31,10 @@ A strategy's primary, backtestable DAG output: one signed, bounded `f64 ∈ [-1,
 **Avoid:** —
 The param-generic, input-role-generic graph-as-data produced by running a Rust builder; it carries free numeric params and free input roles before bootstrap. Bootstrapped into a frozen instance by binding params + data + seed. Registered and inspected headless (`aura graph register`, `aura graph introspect --params` — the raw `param_space` namespace campaign axes bind against; cycle 0107/#196); a *bound* param is an overridable **default** — a sweep axis naming it re-opens it per family (#246), while `run` uses it as-is.
 
+### blueprint label
+**Avoid:** —
+A registry-level name pointing at a registered blueprint's content id (`graph register --name <label>`, #317) — a mutable, latest-wins pointer over the immutable content-addressed store, not a second identity: re-registering under an existing label *repoints* it (the earlier content id stays reachable by its own id, never invalidated). `graph introspect --registered` lists every label with its content-id prefix and root `doc` line — the discovery surface a `use (op)` reference by name resolves against.
+
 ### bootstrap
 **Avoid:** —
 The distinct, recursive construction phase that binds `(blueprint + param-set + data bindings + seed)` into a frozen instance — buffers sized, topology fixed. The explicit name for the "wiring / graph build" that C7/C12 reference — the construction/compilation sense. Disambiguation: the *statistical* moving-block bootstrap of a trade-R series (`r_bootstrap`, `RBootstrap`) is a different thing that keeps its statistics name — it appears as the deflation null, the `aura mc` R path, and since 0108 the `std::monte_carlo` stage's `stage bootstrap` annotation; context (construction vs annotation) disambiguates.
@@ -333,6 +337,10 @@ Since #283 what CONSUMES a declared tap is itself declared per run by a **tap pl
 **Avoid:** —
 The `content id` of a run's signal blueprint in its run-record role: stamped into the manifest as `topology_hash`, keying the reproduction store and anchoring `aura reproduce` — the same SHA-256 over the same canonical bytes. Distinct from the debug-name-blind `identity id`.
 
+### use (op)
+**Avoid:** —
+The construction op that splices a **registered** blueprint into the building graph as a nested `composite` under a chosen instance name (`{"op":"use","ref":{"content_id"|"name":…},"name":…,"bind":{…}}`, #317): the reference — a content id, a unique content-id prefix, or a `blueprint label` — resolves CLI-side, before the engine ever sees it; the fetched composite is C29-gated, spliced, and its resolution echoed on stderr (`aura: note:`, the existing benign marker). The emitted blueprint carries the splice inline as an ordinary nested composite — no reference or registry dependency survives into the artifact. An instance's open input roles become its `<instance>.<role>` in-ports, its output boundary fields its `<instance>.<field>` out-fields — the existing nested-composite param-prefix discipline extends unchanged (`graph.<instance>.<node>.<param>` on `sweep --list-axes`). Pairs with the `input` op: a pattern meant to be `use`d declares its formal parameters as open `input` roles, left unbound at `finish()` (#317's open-pattern amendment) — only running it standalone requires them bound.
+
 ### veto
 **Avoid:** risk-manager
 The **optional** documented pre-trade-gate seam in the execution chain (`stop-rule → [Veto] → position-management`): position / exposure / notional caps that may reject or scale a trade. A pass-through identity DCE'd away when absent (C19/C23); kept as a named seam — it is what LEAN calls "Risk Management" and nautilus the RiskEngine.