diff --git a/lang/el-compiler/src/codegen.el b/lang/el-compiler/src/codegen.el
index 2c10bae..7603b36 100644
--- a/lang/el-compiler/src/codegen.el
+++ b/lang/el-compiler/src/codegen.el
@@ -3223,8 +3223,17 @@ fn cg_fn(stmt: Map<String, Any>) -> Void {
     // strengthen (self-activity) + a dharma bus event — so a decorated op
     // self-reports with ZERO hand-written instrumentation in its body. (VBD role
     // = the topmost decorator; write it topmost when stacking with @route.)
-    if fn_has_decorator(stmt, "manager") || fn_has_decorator(stmt, "accessor") {
-        emit_line("  engram_boundary_beat(EL_STR(" + c_str_lit(fn_name) + "));")
+    // The beat carries the CONSTRUCT that caused it, not only the fn that beat.
+    // Without it the graph accumulates boundary events with no way to attribute
+    // them to the decorator responsible — so no construct can ever be measured,
+    // and "is this decorator earning its keep" stays an argument instead of a
+    // query. One parameter is the whole difference.
+    if fn_has_decorator(stmt, "manager") {
+        emit_line("  engram_boundary_beat(EL_STR(" + c_str_lit(fn_name) + "), EL_STR(" + c_str_lit("manager") + "));")
+    } else {
+        if fn_has_decorator(stmt, "accessor") {
+            emit_line("  engram_boundary_beat(EL_STR(" + c_str_lit(fn_name) + "), EL_STR(" + c_str_lit("accessor") + "));")
+        }
     }
     // Seed declared with parameter names so reassignment works
     let decl = native_list_empty()
diff --git a/lang/runtime/el_runtime.c b/lang/runtime/el_runtime.c
index 441be58..021f3f9 100644
--- a/lang/runtime/el_runtime.c
+++ b/lang/runtime/el_runtime.c
@@ -16991,24 +16991,40 @@ void dharma_emit(el_val_t event_type, el_val_t payload) {
     free(b.buf);
 }
 
-/* engram_boundary_beat(op_name) — the decorated-fn boundary AUTO-EMIT (VBD seam).
- * codegen injects a single call to this at the entry of every @manager/@accessor
- * decorated fn, so a decorated op self-reports with ZERO hand-written
- * instrumentation in its body:
+/* engram_boundary_beat(op_name, construct) — decorated-fn boundary AUTO-EMIT
+ * (VBD seam). codegen injects a single call to this at the entry of every
+ * @manager/@accessor decorated fn, so a decorated op self-reports with ZERO
+ * hand-written instrumentation in its body:
  *   (1) afferent counter++            — the boundary was crossed
  *   (2) engram_chrono_tick()          — interoception: the mind senses its own op firing
  *   (3) engram_strengthen(self-anchor)— reinforce the self-activity anchor (an
  *       activation-count/salience bump, NOT a content/edge write — identity
  *       write-protection is untouched)
  *   (4) dharma_emit(neuron.op.<name>) — provenance on the shared bus transport
- *       (same bus the swarm peers field on); bumps _eg_dharma_emits. */
-el_val_t engram_boundary_beat(el_val_t op_name) {
+ *       (same bus the swarm peers field on); bumps _eg_dharma_emits.
+ *
+ * `construct` is the DECORATOR that caused the beat ("manager" / "accessor"),
+ * carried in the payload. Before it, the beat reported which fn crossed a
+ * boundary but never which construct put the beat there — so boundary events
+ * accumulated in the graph with no attribution, and no decorator could ever be
+ * measured. "Is this construct earning its keep" was an argument; with the
+ * attribution it is a traversal. The payload is built here rather than at the
+ * call site so the format has exactly one author.
+ *
+ * The construct name comes from a closed set codegen controls, so the
+ * unescaped snprintf below cannot be injected through. That is NOT true of
+ * dharma_emit generally — its payloads are hand-concatenated at 39 call sites
+ * with no escaping, and a value containing a quote silently corrupts the
+ * event. Fixing that is a separate change; this one does not add to it. */
+el_val_t engram_boundary_beat(el_val_t op_name, el_val_t construct) {
     _eg_aff_boundary_ops++;
     engram_chrono_tick();
     engram_strengthen(EL_STR("kn-efeb4a5b-5aff-4759-8a97-7233099be6ee"));
-    const char* nm = EL_CSTR(op_name); if (!nm) nm = "";
+    const char* nm = EL_CSTR(op_name);   if (!nm) nm = "";
+    const char* ct = EL_CSTR(construct); if (!ct) ct = "";
     char ev[160]; snprintf(ev, sizeof ev, "neuron.op.%s", nm);
-    dharma_emit(el_wrap_str(el_strdup(ev)), EL_STR(""));
+    char pl[192]; snprintf(pl, sizeof pl, "{\"construct\":\"%s\"}", ct);
+    dharma_emit(el_wrap_str(el_strdup(ev)), el_wrap_str(el_strdup(pl)));
     return (el_val_t)0;
 }
 
diff --git a/lang/runtime/el_runtime.h b/lang/runtime/el_runtime.h
index 716e147..b3e0c9d 100644
--- a/lang/runtime/el_runtime.h
+++ b/lang/runtime/el_runtime.h
@@ -887,7 +887,7 @@ el_val_t  engram_age_field(el_val_t delta_ms);
 el_val_t  engram_age_field_catchup(void);
 el_val_t  engram_chrono_persist_tick(void);
 el_val_t  engram_chrono_tick(void);
-el_val_t  engram_boundary_beat(el_val_t op_name);  /* API-reshape decorator-seam auto-emit */
+el_val_t  engram_boundary_beat(el_val_t op_name, el_val_t construct);  /* API-reshape decorator-seam auto-emit; construct = the decorator that caused the beat */
 el_val_t  engram_self_anchor_capture(void);
 el_val_t  engram_self_drift_json(void);
 el_val_t  engram_neighbors_json(el_val_t node_id, el_val_t max_depth, el_val_t direction);
diff --git a/lang/spec/language.md b/lang/spec/language.md
index df79455..bdf82e5 100644
--- a/lang/spec/language.md
+++ b/lang/spec/language.md
@@ -460,7 +460,7 @@ The `@` token followed by an identifier attaches a decorator to the next `FnDef`
 | Decorator | Structural effect |
 |---|---|
 | `@manager` | Permits calls to `dharma_emit` / `dharma_field`. Calling either from a non-`@manager` fn emits a `#error` into the generated C — a compile-time failure, not a lint. |
-| `@manager`, `@accessor` | Codegen injects one call to `engram_boundary_beat(<fn name>)` at function entry. The decorated op self-reports (chrono tick, afferent counter, self-activity strengthen, dharma bus event) with **zero** hand-written instrumentation in its body. |
+| `@manager`, `@accessor` | Codegen injects one call to `engram_boundary_beat(<fn name>, <construct>)` at function entry, where `<construct>` is the decorator that caused the beat. The decorated op self-reports (chrono tick, afferent counter, self-activity strengthen, dharma bus event carrying `{"construct":"..."}`) with **zero** hand-written instrumentation in its body. Without the construct argument the graph accumulates boundary events with no attribution, so no construct can be measured. |
 | `@route(path, method, …)` | Records a route into a generated dispatch table. |
 
 Decorators with no registered meaning are accepted and ignored.
diff --git a/lang/tests/native/test_compiler.el b/lang/tests/native/test_compiler.el
index 84ad5c4..4f68f78 100644
--- a/lang/tests/native/test_compiler.el
+++ b/lang/tests/native/test_compiler.el
@@ -726,3 +726,49 @@ test "compiler-stdint-include" {
     let out: String = compile_capture(src)
     assert str_contains(out, "stdint.h"), "output includes stdint.h"
 }
+
+// ── Decorator seam: boundary-beat attribution ────────────────────────────────
+//
+// The beat carries the CONSTRUCT that caused it, not only the fn that beat.
+// Without the second argument the graph accumulates boundary events with no
+// way to attribute them to the decorator responsible, so no construct can ever
+// be measured and "is this decorator earning its keep" stays an argument
+// instead of a query.
+
+test "decorator-manager-beat-carries-construct" {
+    let src: String = "@manager\nfn f() -> Int { return 1 }"
+    let out: String = compile_capture(src)
+    assert str_contains(out, "engram_boundary_beat"), "@manager injects the beat"
+    assert str_contains(out, "EL_STR(\"manager\")"), "beat carries the construct that caused it"
+}
+
+test "decorator-accessor-beat-carries-construct" {
+    let src: String = "@accessor\nfn f() -> Int { return 1 }"
+    let out: String = compile_capture(src)
+    assert str_contains(out, "engram_boundary_beat"), "@accessor injects the beat"
+    assert str_contains(out, "EL_STR(\"accessor\")"), "beat carries the construct that caused it"
+}
+
+test "decorator-undecorated-fn-has-no-beat" {
+    let src: String = "fn f() -> Int { return 1 }"
+    let out: String = compile_capture(src)
+    assert !str_contains(out, "engram_boundary_beat"), "an undecorated fn does not beat"
+}
+
+// ── Decorator seam: the twelve inert names ───────────────────────────────────
+//
+// PINS A KNOWN DEFECT. codegen calls fn_has_decorator for exactly three names
+// (manager, accessor, route). Twelve others parse, attach as {name,args}, and
+// compile to nothing — including four that look like protection:
+// @authenticate (6 uses), @authorize (3), @rate_limit (3), @validate (2).
+//
+// This test asserts the CURRENT behaviour so that fixing it is a visible
+// change rather than a silent one. When a pass wires or rejects these, this
+// test flips and that flip is the proof.
+
+test "decorator-authenticate-compiles-to-nothing" {
+    let src: String = "@authenticate\nfn f() -> Int { return 1 }"
+    let out: String = compile_capture(src)
+    let bare: String = compile_capture("fn f() -> Int { return 1 }")
+    assert str_eq(out, bare), "KNOWN DEFECT: @authenticate emits identical C to no decorator at all"
+}