diff --git a/src/game/engine/scenes/hud/unit_panel.gd b/src/game/engine/scenes/hud/unit_panel.gd
index 94a21804..00cb7c1c 100644
--- a/src/game/engine/scenes/hud/unit_panel.gd
+++ b/src/game/engine/scenes/hud/unit_panel.gd
@@ -249,9 +249,6 @@ func _refresh_action_buttons() -> void:
 	var is_fort: bool = _get_is_fortified(_selected_unit)
 	var is_sentry: bool = _get_is_sentrying(_selected_unit)
 	var is_deployed: bool = _get_is_deployed(_selected_unit)
-	var is_embarked: bool = _get_is_embarked(_selected_unit)
-	var adj_water: bool = _get_has_adjacent_water(_selected_unit)
-	var adj_land: bool = _get_has_adjacent_land(_selected_unit)
 
 	var posture: Dictionary = {
 		"is_aiming":              _get_is_aiming(_selected_unit),
@@ -272,7 +269,7 @@ func _refresh_action_buttons() -> void:
 		var bridge: RefCounted = ClassDB.instantiate("GdUnitActions") as RefCounted
 		var raw: Array = bridge.legal_actions_for(
 			unit_type_str, keywords_str, has_movement, is_fort, is_sentry,
-			is_deployed, is_embarked, adj_water, adj_land, posture
+			is_deployed, posture
 		)
 		for entry: Variant in raw:
 			actions.append(entry as Dictionary)
@@ -786,24 +783,6 @@ func _get_is_deployed(unit: RefCounted) -> bool:
 	return bool(unit.get("is_deployed") if "is_deployed" in unit else false)
 
 
-func _get_is_embarked(unit: RefCounted) -> bool:
-	if unit is UnitScript:
-		return (unit as UnitScript).is_embarked
-	return bool(unit.get("is_embarked") if "is_embarked" in unit else false)
-
-
-func _get_has_adjacent_water(unit: RefCounted) -> bool:
-	if unit is UnitScript:
-		return (unit as UnitScript).has_adjacent_water
-	return bool(unit.get("has_adjacent_water") if "has_adjacent_water" in unit else false)
-
-
-func _get_has_adjacent_land(unit: RefCounted) -> bool:
-	if unit is UnitScript:
-		return (unit as UnitScript).has_adjacent_land
-	return bool(unit.get("has_adjacent_land") if "has_adjacent_land" in unit else false)
-
-
 ## p2-53g: fire arrows toggle state — read by legal_actions_for bridge.
 func _get_is_fire_arrows(unit: RefCounted) -> bool:
 	if unit is UnitScript:
diff --git a/src/game/engine/src/entities/unit.gd b/src/game/engine/src/entities/unit.gd
index 88c52137..189fc69e 100644
--- a/src/game/engine/src/entities/unit.gd
+++ b/src/game/engine/src/entities/unit.gd
@@ -69,14 +69,9 @@ var fortified_turns: int = 0
 var is_sentrying: bool = false
 ## True when a siege unit is in deployed posture (cannot move, can Bombard).
 var is_deployed: bool = false
-## True when an amphibious unit is on a water tile.
+## True when a land unit is embarked on a water tile (p3-18). Mirrors the Rust
+## MapUnit::is_embarked; round-tripped for save/load.
 var is_embarked: bool = false
-## True when the unit's current tile has at least one adjacent water hex.
-## Populated each turn by the world-map via WorldMap._refresh_unit_terrain_context().
-var has_adjacent_water: bool = false
-## True when the unit's current tile has at least one adjacent land hex.
-## Populated each turn by the world-map via WorldMap._refresh_unit_terrain_context().
-var has_adjacent_land: bool = false
 
 # ── Veterancy ─────────────────────────────────────────────────────────
 var xp: int = 0
@@ -318,9 +313,6 @@ func get_legal_actions() -> Array[Dictionary]:
 		is_fortified,
 		is_sentrying,
 		is_deployed,
-		is_embarked,
-		has_adjacent_water,
-		has_adjacent_land,
 		{}
 	)
 
@@ -337,9 +329,6 @@ func can_invoke_action(kind: String) -> bool:
 		is_fortified,
 		is_sentrying,
 		is_deployed,
-		is_embarked,
-		has_adjacent_water,
-		has_adjacent_land,
 		kind
 	)
 
@@ -444,8 +433,6 @@ func to_save_dict() -> Dictionary:
 		"is_sentrying": is_sentrying,
 		"is_deployed": is_deployed,
 		"is_embarked": is_embarked,
-		"has_adjacent_water": has_adjacent_water,
-		"has_adjacent_land": has_adjacent_land,
 		"xp": xp,
 		"level": level,
 		"base_str": base_str,
@@ -505,8 +492,6 @@ func from_save_dict(data: Dictionary) -> void:
 	is_sentrying = bool(data.get("is_sentrying", is_sentrying))
 	is_deployed = bool(data.get("is_deployed", is_deployed))
 	is_embarked = bool(data.get("is_embarked", is_embarked))
-	has_adjacent_water = bool(data.get("has_adjacent_water", has_adjacent_water))
-	has_adjacent_land = bool(data.get("has_adjacent_land", has_adjacent_land))
 	xp = int(data.get("xp", xp))
 	level = int(data.get("level", level))
 	base_str = int(data.get("base_str", base_str))
diff --git a/src/game/engine/tests/unit/entities/test_unit_actions.gd b/src/game/engine/tests/unit/entities/test_unit_actions.gd
index 3efc6759..0e775ca5 100644
--- a/src/game/engine/tests/unit/entities/test_unit_actions.gd
+++ b/src/game/engine/tests/unit/entities/test_unit_actions.gd
@@ -116,7 +116,7 @@ func test_gd_unit_actions_bridge_legal_actions_for_military() -> void:
 		pass_test("GdUnitActions not loaded in headless — skipping bridge test")
 		return
 	var bridge: RefCounted = ClassDB.instantiate("GdUnitActions") as RefCounted
-	var actions: Array[Dictionary] = bridge.legal_actions_for("military", "", true, false, false, false, false, false, false, {})
+	var actions: Array[Dictionary] = bridge.legal_actions_for("military", "", true, false, false, false, {})
 	assert_true(actions.size() >= 2, "military unit with movement gets multiple actions")
 	var kinds: Array[String] = []
 	for d: Dictionary in actions:
@@ -130,7 +130,7 @@ func test_gd_unit_actions_bridge_founder_gets_found_city() -> void:
 		pass_test("GdUnitActions not loaded in headless — skipping bridge test")
 		return
 	var bridge: RefCounted = ClassDB.instantiate("GdUnitActions") as RefCounted
-	var actions: Array[Dictionary] = bridge.legal_actions_for("civilian", "founder", true, false, false, false, false, false, false, {})
+	var actions: Array[Dictionary] = bridge.legal_actions_for("civilian", "founder", true, false, false, false, {})
 	var kinds: Array[String] = []
 	for d: Dictionary in actions:
 		kinds.append(d.get("kind", ""))
@@ -142,7 +142,7 @@ func test_gd_unit_actions_bridge_fortified_cannot_fortify_again() -> void:
 		pass_test("GdUnitActions not loaded in headless — skipping bridge test")
 		return
 	var bridge: RefCounted = ClassDB.instantiate("GdUnitActions") as RefCounted
-	var actions: Array[Dictionary] = bridge.legal_actions_for("military", "", false, true, false, false, false, false, false, {})
+	var actions: Array[Dictionary] = bridge.legal_actions_for("military", "", false, true, false, false, {})
 	for d: Dictionary in actions:
 		if d.get("kind", "") == "fortify":
 			assert_false(d.get("enabled", true), "fortify disabled when already fortified")
@@ -154,7 +154,7 @@ func test_gd_unit_actions_bridge_sentrying_unit_shows_unsentry() -> void:
 		return
 	var bridge: RefCounted = ClassDB.instantiate("GdUnitActions") as RefCounted
 	# is_sentrying = true
-	var actions: Array[Dictionary] = bridge.legal_actions_for("melee", "", true, false, true, false, false, false, false, {})
+	var actions: Array[Dictionary] = bridge.legal_actions_for("melee", "", true, false, true, false, {})
 	var by_kind: Dictionary = {}
 	for d: Dictionary in actions:
 		by_kind[d.get("kind", "")] = d
diff --git a/src/game/engine/tests/unit/test_unit_serialize.gd b/src/game/engine/tests/unit/test_unit_serialize.gd
index 6329df81..7fff790e 100644
--- a/src/game/engine/tests/unit/test_unit_serialize.gd
+++ b/src/game/engine/tests/unit/test_unit_serialize.gd
@@ -42,8 +42,6 @@ const REQUIRED_KEYS: Array[String] = [
 	"is_sentrying",
 	"is_deployed",
 	"is_embarked",
-	"has_adjacent_water",
-	"has_adjacent_land",
 	"xp",
 	"level",
 	"base_str",
diff --git a/src/simulator/api-gdext/src/action.rs b/src/simulator/api-gdext/src/action.rs
index bfc580de..2bcd33aa 100644
--- a/src/simulator/api-gdext/src/action.rs
+++ b/src/simulator/api-gdext/src/action.rs
@@ -2,15 +2,11 @@
 //!
 //! Exposes `GdUnitActions` to GDScript:
 //! - `legal_actions_for(unit_type, keywords, has_movement, is_fortified, is_sentrying,
-//!                      is_deployed, is_embarked, adjacent_water, adjacent_land,
-//!                      posture)` →
+//!                      is_deployed, posture)` →
 //!   `Array[Dictionary]` with `{kind, enabled, disabled_reason}` entries
 //!
-//!   NOTE (p3-18): `is_embarked` / `adjacent_water` / `adjacent_land` are
-//!   vestigial — embarkation is now automatic (Civ-VI: move onto water →
-//!   embarked) with no explicit Embark/Disembark action, so these inputs no
-//!   longer affect legality. They remain in the signature for ABI stability and
-//!   are slated for removal in the P5 GDScript-mirror pass.
+//!   (p3-18: embarkation is automatic — move onto water → embarked, no explicit
+//!   Embark action — so the old embark/adjacency inputs were dropped.)
 //!
 //!   `posture` is a Dictionary carrying archetype state fields (all optional,
 //!   defaulting to false/0 if absent):
@@ -61,16 +57,8 @@ impl GdUnitActions {
         is_fortified: bool,
         is_sentrying: bool,
         is_deployed: bool,
-        is_embarked: bool,
-        adjacent_water: bool,
-        adjacent_land: bool,
         posture: Dictionary,
     ) -> Array<Dictionary> {
-        // p3-18 — embarkation is auto (Civ-VI): there is no explicit Embark
-        // action, so these legacy embark inputs no longer affect action
-        // legality. Accepted for ABI stability; the bridge + GDScript callers
-        // shed them in the p3-18 P5 GDScript-mirror pass.
-        let _ = (is_embarked, adjacent_water, adjacent_land);
         let cap = UnitCapability {
             unit_type: unit_type.to_string(),
             keywords: keywords
@@ -122,9 +110,6 @@ impl GdUnitActions {
         is_fortified: bool,
         is_sentrying: bool,
         is_deployed: bool,
-        is_embarked: bool,
-        adjacent_water: bool,
-        adjacent_land: bool,
         posture: Dictionary,
         kind: GString,
     ) -> bool {
@@ -132,9 +117,6 @@ impl GdUnitActions {
         let Some(action_kind) = ActionKind::from_str(&kind_str) else {
             return false;
         };
-        // p3-18 — auto-embark: legacy embark inputs no longer affect legality
-        // (see legal_actions_for). Kept for ABI stability; trimmed in P5.
-        let _ = (is_embarked, adjacent_water, adjacent_land);
         let cap = UnitCapability {
             unit_type: unit_type.to_string(),
             keywords: keywords