diff --git a/tier1/asl-domain-model-1.md b/tier1/asl-domain-model-1.md
index f29d9b3..bda2c13 100644
--- a/tier1/asl-domain-model-1.md
+++ b/tier1/asl-domain-model-1.md
@@ -165,3 +165,6 @@ ASL/DOMAIN-MODEL/1 does not define:
 
 Middle layer (informative): the daemon/service boundary around core logic that
 owns network transport, admission workflows, and operational policy.
+
+Implementation note (informative): core federation primitives live in
+`include/amduat/fed/{registry,ingest,replay,view}.h`.
diff --git a/tier1/asl-federation-1.md b/tier1/asl-federation-1.md
index 8b796d7..12eb7bd 100644
--- a/tier1/asl-federation-1.md
+++ b/tier1/asl-federation-1.md
@@ -182,6 +182,9 @@ Federation MUST NOT bypass ASL/LOG/1 ordering or ASL/1-CORE-INDEX semantics.
 Middle layer (informative): the daemon/service boundary around core logic that
 owns network transport, admission workflows, and operational policy.
 
+Implementation note (informative): core federation primitives live in
+`include/amduat/fed/{registry,ingest,replay,view}.h`.
+
 ---
 
 ## 12. Summary
diff --git a/tier1/asl-system-1.md b/tier1/asl-system-1.md
index a2cbc84..0f4a231 100644
--- a/tier1/asl-system-1.md
+++ b/tier1/asl-system-1.md
@@ -80,6 +80,9 @@ Non-goals:
 Middle layer (informative): the daemon/service boundary around core logic that
 owns network transport, admission workflows, and operational policy.
 
+Implementation note (informative): core federation primitives live in
+`include/amduat/fed/{registry,ingest,replay,view}.h`.
+
 ---
 
 ## 2. Core Objects (Unified View)