diff --git a/client/scripts/autoloads/fog_state.gd b/client/scripts/autoloads/fog_state.gd
index 49b10d57c..f36f5a898 100644
--- a/client/scripts/autoloads/fog_state.gd
+++ b/client/scripts/autoloads/fog_state.gd
@@ -8,7 +8,7 @@ extends Node
 # Used by fog shader to distinguish visual treatment per tile.
 # Test assertions reference these: assert_that(byte).is_equal(FogState.VIS_FORWARD)
 const VIS_HIDDEN: int = 0        # Not in LOS — fully fogged
-const VIS_PERIPHERAL: int = 180  # In LOS, peripheral sector — light fog dimming
+const VIS_PERIPHERAL: int = 180  # DEPRECATED: peripheral sector removed in Sprint 22 (#569). Retained — tests still reference it.
 const VIS_FORWARD: int = 255     # In LOS, forward sector — clear vision
 
 const EXP_UNEXPLORED: int = 0   # Never seen — total darkness
diff --git a/docs/architecture/fog-shader-spec.md b/docs/architecture/fog-shader-spec.md
index 86fc4c448..3213eb205 100644
--- a/docs/architecture/fog-shader-spec.md
+++ b/docs/architecture/fog-shader-spec.md
@@ -11,7 +11,7 @@ The fog system was simplified from the original 5-layer spec in Sprint 22 (#569)
 | Original D-059 Layer | Sprint 22 Status | Notes |
 |----------------------|------------------|-------|
 | 1. Clear (forward cone) | Implemented | Soft Gaussian gradient (7x7, sigma 2.0) |
-| 2. Light fog (peripheral sector) | Simplified — merged into gradient | Peripheral sector removed from server; gradient provides soft transition |
+| 2. Light fog (cone gradient) | Simplified — merged into gradient | Peripheral sector removed from server (#569); Gaussian blur provides soft transition |
 | 3. Deep fog (previously explored) | Implemented — EXP_EXPLORED | Alpha 0.55-0.70 with zone temperature tint (#563) |
 | 4. Unexplored + maps app | Deferred | v0.1.2+, requires mapped_tiles in ObserverSnapshot |
 | 5. Unexplored (no maps) | Implemented | Solid near-black #12141a |