diff --git a/restoration/source410/BT/MECH-LAYOUT.md b/restoration/source410/BT/MECH-LAYOUT.md
index 45abf970..d71a7867 100644
--- a/restoration/source410/BT/MECH-LAYOUT.md
+++ b/restoration/source410/BT/MECH-LAYOUT.md
@@ -82,7 +82,7 @@ Settles the open item in the "Real 1995 types" bullet above:
 |---|---|---|
 | ReconAlarm (AlarmIndicator) | AlarmIndicator (multi-level, N levels sets size) | ❌ MISSING |
 | ReconSeq | SequenceController (animation sequence) | ❌ MISSING |
-| ReconFiltered / FilteredScalar | AverageOf<Scalar> (15-sample running avg) | ❌ MISSING |
+| ReconFiltered / FilteredScalar | **AverageOf<Scalar>** (15-sample running avg) | ✅ AVERAGE.HPP |
 | ReconFiltered (mechNameFilter) | NameFilter | ❌ MISSING |
 | ReconChain<Subsystem*> | ChainOf<Subsystem*> | ✅ CHAIN.HPP |
 | ReconMatrix / Matrix34 | AffineMatrix / Matrix | ✅ |
@@ -90,11 +90,14 @@ Settles the open item in the "Real 1995 types" bullet above:
 | Reticle | Reticle | ✅ RETICLE.HPP |
 | BTVal (turretBase, mechName, torsoAim*, aimRate, headPitch, torsoTwist) | animated value/quaternion — **UNIDENTIFIED**; BT411 BTVal is a no-op placeholder. Most BTVal members are < 0x328 = BASE-class pose fields (re-attribute per §"Consequences"), so their type is a base concern, not Mech's. |
 
-### CRITICAL new finding — embedded helper classes are ALSO missing
+### CRITICAL new finding — 3 embedded helper classes are missing
 
-`AlarmIndicator`, `SequenceController`, `NameFilter`, `AverageOf` do **not** exist anywhere in
-the 4.10 CODE archive (confirmed by full-tree grep). They are additional helper classes the
-milestone must reconstruct, and their sizes set the embedded-member offsets — so the
+`AlarmIndicator`, `SequenceController`, `NameFilter` do **not** exist anywhere in the 4.10
+CODE archive (confirmed by full-tree grep; no *alarm*/*filter*/*sequen* headers either).
+They are additional helper classes the milestone must reconstruct from BT411's decomp, and
+their sizes set the embedded-member offsets. (`AverageOf` was initially flagged missing but
+DOES survive — AVERAGE.HPP, same SIGNATURED lineage BT411 preserved — so telemetryFilter[5]'s
+type is available.) The alarm sizing: the
 `masterAlarm@0x39C`/`heatAlarm@0x450`/`stabilityAlarm@0x4C4`/`statusAlarm@0x714` spacing
 DERIVES the AlarmIndicator per-level size (e.g. masterAlarm 33 levels spans 0x39C..0x450 =
 0xB4; heatAlarm 3 levels spans 0x450..0x4C4 = 0x74 — a fixed header + N-level array; solve
@@ -112,8 +115,8 @@ legAnimation/bodyAnimation spacing.
 
 ### Revised reconstruction order
 
-1. **Helper classes** (block the layout): AlarmIndicator, SequenceController, NameFilter,
-   AverageOf<Scalar> — sizes solved from the offset-spacing equations above; identify BTVal.
+1. **Helper classes** (block the layout): AlarmIndicator, SequenceController, NameFilter
+   (AverageOf survives) — from BT411 decomp; identify BTVal (mostly base-class pose fields).
 2. **MechSubsystem base + roster** (GAUSS/PPC/SENSOR + .TCP partials + decomp).
 3. **Finalize MECH.HPP** per the offset map; probe sizeof(Mech)==0x854.
 4. **Mech ctor** (@004a1674): embedded construction + segment-table walk.