diff --git a/.serena/project.yml b/.serena/project.yml
index 0abd05a..90a1c0f 100644
--- a/.serena/project.yml
+++ b/.serena/project.yml
@@ -169,3 +169,17 @@ read_only_memory_patterns: []
 # Extends the list from the global configuration, merging the two lists.
 # Example: ["_archive/.*", "_episodes/.*"]
 ignored_memory_patterns: []
+
+# list of APIs (facades or facade methods, e.g. "lsp" or "lsp.get_diagnostics_for_symbol") to include in the REPL
+# that would otherwise be disabled (particularly optional methods, which are disabled by default).
+# This extends the existing inclusions (e.g. from the global configuration).
+included_apis: []
+
+# list of APIs (facades or facade methods, e.g. "lsp" or "lsp.find_symbol") to exclude from the REPL.
+# This extends the existing exclusions (e.g. from the global configuration).
+excluded_apis: []
+
+# The interface through which the agent (LLM) accesses Serena's functionality (overrides the global setting).
+# Valid values: tools, REPL (see the global configuration for details); leave empty to use the global setting.
+# Note: the interface is fixed at startup. If a project is activated post-init, its setting is not applied.
+agent_interface:
diff --git a/game/content/loader.gd b/game/content/loader.gd
index a7a23eb..fb4563a 100644
--- a/game/content/loader.gd
+++ b/game/content/loader.gd
@@ -55,6 +55,10 @@ const TUNING_SCHEMA := {
 		"grid_line_alpha": "number",
 		"device_pixel_ratio_cap": "number",
 		"pause_vignette_alpha": "number",
+		"wall_border_width_px": "number",
+		"wall_border_alpha": "number",
+		"wall_border_wrap_alpha": "number",
+		"wall_border_wrap_dash_fraction": "number",
 	},
 	"input": {
 		"swipe_threshold_cell_fraction": "number",
@@ -82,6 +86,7 @@ const PALETTE_SCHEMA := {
 		"background": TYPE_STRING,
 		"checkerboard_tile": TYPE_STRING,
 		"grid_line": TYPE_STRING,
+		"wall_border": TYPE_STRING,
 		"food_fill": TYPE_STRING,
 		"food_shadow": TYPE_STRING,
 		"snake_head_fill": TYPE_STRING,
diff --git a/game/content/palette.json b/game/content/palette.json
index 59968ab..bfabb09 100644
--- a/game/content/palette.json
+++ b/game/content/palette.json
@@ -16,14 +16,26 @@
     "background": "#0c1628",
     "checkerboard_tile": "#ffffff",
     "grid_line": "#38bdf8",
+    "wall_border": "#e2e8f0",
     "food_fill": "#ef4444",
     "food_shadow": "#f87171",
     "snake_head_fill": "#a7f3d0",
     "snake_head_shadow": "#4ade80",
-    "snake_body_base_rgb": [74, 222, 128],
-    "snake_body_rgb_delta": [30, -20, 30],
+    "snake_body_base_rgb": [
+      74,
+      222,
+      128
+    ],
+    "snake_body_rgb_delta": [
+      30,
+      -20,
+      30
+    ],
     "eye_fill": "#062c1a",
-    "particle_hues": ["#f87171", "#fbbf24"],
+    "particle_hues": [
+      "#f87171",
+      "#fbbf24"
+    ],
     "flash_dead": "#ef4444",
     "flash_eat": "#fbbf24",
     "pause_vignette": "#060b16"
diff --git a/game/content/tuning.json b/game/content/tuning.json
index 04360c4..204e653 100644
--- a/game/content/tuning.json
+++ b/game/content/tuning.json
@@ -34,7 +34,11 @@
     "checkerboard_alpha": 0.019,
     "grid_line_alpha": 0.055,
     "device_pixel_ratio_cap": 2,
-    "pause_vignette_alpha": 0.55
+    "pause_vignette_alpha": 0.55,
+    "wall_border_width_px": 2.5,
+    "wall_border_alpha": 0.3,
+    "wall_border_wrap_alpha": 0.1,
+    "wall_border_wrap_dash_fraction": 0.55
   },
   "input": {
     "swipe_threshold_cell_fraction": 0.5
diff --git a/game/main.tscn b/game/main.tscn
index 9ac1dfe..7d333b4 100644
--- a/game/main.tscn
+++ b/game/main.tscn
@@ -6,5 +6,5 @@
 layout_mode = 3
 anchors_preset = 0
 offset_right = 520.0
-offset_bottom = 600.0
+offset_bottom = 545.0
 script = ExtResource("1")
diff --git a/game/presentation/board/board_geometry.gd b/game/presentation/board/board_geometry.gd
index db3023a..fc59fba 100644
--- a/game/presentation/board/board_geometry.gd
+++ b/game/presentation/board/board_geometry.gd
@@ -9,7 +9,7 @@ extends RefCounted
 ## operationalized as data so board_view.gd's _draw() order can be pinned by
 ## a test instead of relying on code review alone (AC#4).
 const DRAW_LAYER_ORDER := [
-	"background", "checkerboard", "grid", "food", "snake", "eyes",
+	"background", "checkerboard", "grid", "walls", "food", "snake", "eyes",
 	"particles", "flash", "pause_vignette",
 ]
 
@@ -96,7 +96,7 @@ static func build_checkerboard_image(cols: int, rows: int, tile_color: Color, al
 
 ## Decodes the fields of docs/canonical-state.md's 44-byte header that
 ## board_view.gd needs and has no other accessor for (cols/rows/food
-## position aren't exposed by SimulationWorld.player_view_get or
+## position/wrap flag aren't exposed by SimulationWorld.player_view_get or
 ## .body_copy). PackedByteArray.decode_u16 is little-endian, matching the
 ## canonical format's own endianness.
 static func decode_canon_header(bytes: PackedByteArray) -> Dictionary:
@@ -105,4 +105,32 @@ static func decode_canon_header(bytes: PackedByteArray) -> Dictionary:
 		"rows": bytes.decode_u16(12),
 		"food_x": bytes.decode_u16(40),
 		"food_y": bytes.decode_u16(42),
+		"wrap": (bytes.decode_u16(14) & 1) != 0,
 	}
+
+## draw_rect()'s unfilled outline is centered on its own boundary, so a
+## `thickness`-px border around the board must be inset by half its own
+## width on every side to stay inside the 0..cols*cell / 0..rows*cell rect
+## that core/world.zig:340's bounds check actually kills you on.
+static func wall_border_rect(cols: int, rows: int, cell: float, thickness: float) -> Rect2:
+	var half := thickness / 2.0
+	return Rect2(half, half, cols * cell - thickness, rows * cell - thickness)
+
+## One dash per perimeter cell (`wrap` mode's edge is passable, so the
+## border reads as a broken line rather than solid), each centered on that
+## cell along the same half-thickness-inset boundary wall_border_rect()
+## draws solid. Returns an Array of [from: Vector2, to: Vector2] pairs.
+static func wall_dash_segments(cols: int, rows: int, cell: float, thickness: float, dash_fraction: float) -> Array:
+	var half := thickness / 2.0
+	var dash := cell * dash_fraction
+	var pad := (cell - dash) / 2.0
+	var out := []
+	for x in cols:
+		var cx := x * cell + pad
+		out.append([Vector2(cx, half), Vector2(cx + dash, half)])
+		out.append([Vector2(cx, rows * cell - half), Vector2(cx + dash, rows * cell - half)])
+	for y in rows:
+		var cy := y * cell + pad
+		out.append([Vector2(half, cy), Vector2(half, cy + dash)])
+		out.append([Vector2(cols * cell - half, cy), Vector2(cols * cell - half, cy + dash)])
+	return out
diff --git a/game/presentation/board/board_view.gd b/game/presentation/board/board_view.gd
index db50fba..eb87357 100644
--- a/game/presentation/board/board_view.gd
+++ b/game/presentation/board/board_view.gd
@@ -72,6 +72,7 @@ func _draw() -> void:
 		_draw_background(cols, rows, cell)
 		_draw_checkerboard(cols, rows, cell)
 		_draw_grid(cols, rows, cell)
+		_draw_walls(header, cols, rows, cell)
 		_draw_food(header, cell)
 	if body.result == SimulationWorld.OK:
 		_draw_snake(body.cells, cell)
@@ -103,6 +104,21 @@ func _draw_grid(cols: int, rows: int, cell: float) -> void:
 	for y in BoardGeometry.grid_line_offsets(rows, cell):
 		draw_line(Vector2(0, y), Vector2(cols * cell, y), color, 1.0)
 
+## Solid in wall mode (the edge kills you); dim and dashed in wrap mode
+## (the edge is passable) -- reference/snake.html has no equivalent, this
+## is the port's own answer to grid_line_offsets() drawing interior lines
+## only (board_geometry.gd:78-82) and leaving the actual kill line invisible.
+func _draw_walls(header: Dictionary, cols: int, rows: int, cell: float) -> void:
+	var width: float = tuning.render.wall_border_width_px
+	var color := Color(palette.board.wall_border)
+	if header.wrap:
+		color.a = tuning.render.wall_border_wrap_alpha
+		for segment in BoardGeometry.wall_dash_segments(cols, rows, cell, width, tuning.render.wall_border_wrap_dash_fraction):
+			draw_line(segment[0], segment[1], color, width)
+	else:
+		color.a = tuning.render.wall_border_alpha
+		draw_rect(BoardGeometry.wall_border_rect(cols, rows, cell, width), color, false, width)
+
 func _draw_food(header: Dictionary, cell: float) -> void:
 	if header.food_x == BoardGeometry.NO_CELL_COORD:
 		return
diff --git a/game/presentation/screens/game_screen.gd b/game/presentation/screens/game_screen.gd
index 555a95c..0fe934a 100644
--- a/game/presentation/screens/game_screen.gd
+++ b/game/presentation/screens/game_screen.gd
@@ -88,7 +88,7 @@ var _save_data: Dictionary
 var _settings_open := false
 
 func _ready() -> void:
-	## project.godot's viewport_width/height (520x600) is only the design
+	## project.godot's viewport_width/height (520x545) is only the design
 	## canvas that canvas_items/keep stretch scales up to fill the window --
 	## it's also the actual initial OS window size unless overridden here,
 	## since window_width_override/height_override (the project-settings
@@ -99,12 +99,12 @@ func _ready() -> void:
 	## QHD/4K display doesn't blow the board up past a sane on-screen size.
 	## Window.size is in physical pixels, not the OS window manager's points
 	## -- on a Retina/hiDPI display (screen_get_scale() > 1) an unscaled
-	## Vector2i(780, 900) here nets a window that visually measures half
+	## Vector2i(780, 817.5) here nets a window that visually measures half
 	## that on screen, so the target size must be scaled up to compensate.
 	var screen := DisplayServer.window_get_current_screen()
 	var display_scale := DisplayServer.screen_get_scale(screen)
-	get_window().size = Vector2i(Vector2(780, 900) * display_scale)
-	get_window().max_size = Vector2i(Vector2(936, 1080) * display_scale)
+	get_window().size = Vector2i(Vector2(780, 817.5) * display_scale)
+	get_window().max_size = Vector2i(Vector2(936, 981) * display_scale)
 
 	var content := ContentLoader.load_all()
 	if not content.ok:
@@ -169,6 +169,8 @@ func _ready() -> void:
 	overlay.return_to_title_requested.connect(_on_return_to_title_requested)
 	overlay.mode_selected.connect(_on_mode_selected)
 	overlay.settings_requested.connect(_on_settings_requested)
+	overlay.set_quit_available(not OS.has_feature("web"))
+	overlay.quit_requested.connect(_quit_game)
 
 	settings_panel = SettingsPanel.new()
 	settings_panel.position = board_view.position
@@ -235,16 +237,21 @@ func _capture_state_arg() -> String:
 			return arg.substr("--capture-state=".length())
 	return ""
 
+## NOTIFICATION_WM_CLOSE_REQUEST fires for both a window close and a
+## terminal SIGINT, so routing it through _quit_game() covers both.
+func _notification(what: int) -> void:
+	if what == NOTIFICATION_WM_CLOSE_REQUEST:
+		_quit_game()
+
 ## A still-looping AudioStreamOggVorbis at process exit leaks its playback
 ## objects (AudioStreamPlaybackOggVorbis/OggPacketSequencePlayback) --
 ## Godot only releases them cleanly once AudioStreamPlayer.stop() has run,
-## not merely on the node being freed. NOTIFICATION_WM_CLOSE_REQUEST fires
-## for both a window close and a terminal SIGINT, so this covers both.
-func _notification(what: int) -> void:
-	if what == NOTIFICATION_WM_CLOSE_REQUEST:
-		if music != null:
-			music.stop()
-		get_tree().quit()
+## not merely on the node being freed. Shared by the window-close path
+## above and the title screen's own Quit button.
+func _quit_game() -> void:
+	if music != null:
+		music.stop()
+	get_tree().quit()
 
 func _process(delta: float) -> void:
 	var pre_food_x := BoardGeometry.NO_CELL_COORD
diff --git a/game/presentation/screens/game_screen_state.gd b/game/presentation/screens/game_screen_state.gd
index 781f820..7abdd4c 100644
--- a/game/presentation/screens/game_screen_state.gd
+++ b/game/presentation/screens/game_screen_state.gd
@@ -51,6 +51,7 @@ static func overlay_content(screen: String, score: int, best: int, snake_len: in
 				"show_mode_select": true,
 				"show_player_select": true,
 				"show_return_to_title": false,
+				"show_quit": true,
 				"controls": CONTROLS_LEGEND,
 			}
 		SCREEN_PAUSED:
@@ -61,6 +62,7 @@ static func overlay_content(screen: String, score: int, best: int, snake_len: in
 				"show_mode_select": false,
 				"show_player_select": false,
 				"show_return_to_title": false,
+				"show_quit": false,
 				"controls": "",
 			}
 		SCREEN_DEAD:
@@ -72,6 +74,7 @@ static func overlay_content(screen: String, score: int, best: int, snake_len: in
 					"show_mode_select": false,
 					"show_player_select": false,
 					"show_return_to_title": true,
+					"show_quit": false,
 					"controls": "",
 				}
 			return {
@@ -81,6 +84,7 @@ static func overlay_content(screen: String, score: int, best: int, snake_len: in
 				"show_mode_select": false,
 				"show_player_select": false,
 				"show_return_to_title": true,
+				"show_quit": false,
 				"controls": "",
 			}
 		_:
diff --git a/game/presentation/screens/hud.gd b/game/presentation/screens/hud.gd
index de68254..76b3388 100644
--- a/game/presentation/screens/hud.gd
+++ b/game/presentation/screens/hud.gd
@@ -7,39 +7,44 @@ extends Control
 ## (snake.html:218-223), which this task's text never asks for. Built in
 ## code, matching board_view.gd's code-first Control convention: this repo
 ## has no .tscn precedent to follow instead.
+##
+## Both players' fields share a single HBoxContainer row (game_screen.gd
+## sets custom_minimum_size.y to the 25px strip below the board, which only
+## fits one text row) rather than the two stacked rows an earlier version
+## used.
 
 var _score_label := Label.new()
 var _best_label := Label.new()
 var _status_label := Label.new()
 
-## TASK-051: player 1's own row. No best-score label -- best-score
+## TASK-051: player 1's own fields. No best-score label -- best-score
 ## persistence stays player-0/mode-scoped only (see backlog/decisions).
 var _p2_score_label := Label.new()
 var _p2_status_label := Label.new()
 var _p2_box: HBoxContainer
 
+const _FONT_SIZE := 14
+
 func _ready() -> void:
-	## Both rows are plain Control children with no shared layout container,
-	## so without this VBoxContainer wrapper they both default to (0, 0)
-	## and render on top of each other.
-	var rows := VBoxContainer.new()
-	add_child(rows)
-
-	var box := HBoxContainer.new()
-	box.add_theme_constant_override("separation", 16)
-	rows.add_child(box)
-	box.add_child(_score_label)
-	box.add_child(_best_label)
-	box.add_child(_status_label)
+	custom_minimum_size = Vector2(0, 25)
+	var row := HBoxContainer.new()
+	row.add_theme_constant_override("separation", 16)
+	add_child(row)
+	row.add_child(_score_label)
+	row.add_child(_best_label)
+	row.add_child(_status_label)
 	update(0, 0, "")
 
 	_p2_box = HBoxContainer.new()
 	_p2_box.add_theme_constant_override("separation", 16)
-	rows.add_child(_p2_box)
+	row.add_child(_p2_box)
 	_p2_box.add_child(_p2_score_label)
 	_p2_box.add_child(_p2_status_label)
 	update_p2(0, "")
 
+	for label in [_score_label, _best_label, _status_label, _p2_score_label, _p2_status_label]:
+		label.add_theme_font_size_override("font_size", _FONT_SIZE)
+
 ## status_text mirrors the S.status equivalent transition currently in
 ## effect (menu/playing/paused/dead) -- not part of the oracle's own HUD,
 ## but explicit in this task's Description ("status text matching S.status
diff --git a/game/presentation/screens/overlay_panel.gd b/game/presentation/screens/overlay_panel.gd
index 136a61a..3d6354c 100644
--- a/game/presentation/screens/overlay_panel.gd
+++ b/game/presentation/screens/overlay_panel.gd
@@ -21,6 +21,7 @@ signal player_count_selected(count: int)
 signal return_to_title_requested
 signal mode_selected(mode_id: String)
 signal settings_requested
+signal quit_requested
 
 var _title_label := Label.new()
 var _sub_label := Label.new()
@@ -42,6 +43,14 @@ var _action_button := Button.new()
 var _return_button := Button.new()
 
 var _settings_button := Button.new()
+
+## Menu-only, same as the mode select/player-count buttons. Hidden outright
+## on a platform where quitting is impossible (a browser tab -- see
+## game_screen.gd's OS.has_feature("web") check) via set_quit_available(),
+## not just left visible and inert.
+var _quit_button := Button.new()
+var _quit_available := true
+
 var _mode_ids: Array[String] = []
 
 ## Tracks the visible->hidden/hidden->visible edge across configure() calls
@@ -73,12 +82,15 @@ func _ready() -> void:
 	box.add_child(_return_button)
 	_settings_button.text = "Settings"
 	box.add_child(_settings_button)
+	_quit_button.text = "Quit"
+	box.add_child(_quit_button)
 	_action_button.pressed.connect(func() -> void: action_pressed.emit())
 	_return_button.pressed.connect(func() -> void: return_to_title_requested.emit())
 	_one_player_button.pressed.connect(func() -> void: player_count_selected.emit(1))
 	_two_player_button.pressed.connect(func() -> void: player_count_selected.emit(2))
 	_mode_select.item_selected.connect(_on_item_selected)
 	_settings_button.pressed.connect(func() -> void: settings_requested.emit())
+	_quit_button.pressed.connect(func() -> void: quit_requested.emit())
 
 func _on_item_selected(index: int) -> void:
 	mode_selected.emit(_mode_ids[index])
@@ -118,3 +130,10 @@ func configure(content: Dictionary) -> void:
 	_controls_label.text = content.controls
 	_controls_label.visible = content.controls != ""
 	_mode_select.visible = content.show_mode_select
+	_quit_button.visible = content.show_quit and _quit_available
+
+## game_screen.gd calls this once, before the first configure(), with
+## `not OS.has_feature("web")` -- a browser tab can't quit itself, so
+## get_tree().quit() would be a visible no-op there.
+func set_quit_available(available: bool) -> void:
+	_quit_available = available
diff --git a/game/project.godot b/game/project.godot
index 84e78b9..833479e 100644
--- a/game/project.godot
+++ b/game/project.godot
@@ -18,7 +18,7 @@ run/main_scene="res://main.tscn"
 [display]
 
 window/size/viewport_width=520
-window/size/viewport_height=600
+window/size/viewport_height=545
 window/stretch/mode="canvas_items"
 window/stretch/aspect="keep"
 
diff --git a/game/tests/test_board_geometry.gd b/game/tests/test_board_geometry.gd
index c86ea37..08894a4 100644
--- a/game/tests/test_board_geometry.gd
+++ b/game/tests/test_board_geometry.gd
@@ -107,10 +107,52 @@ func test_decode_canon_header_passes_through_no_cell_coord_unchanged() -> void:
 	assert_int(header.food_y).is_equal(BoardGeometry.NO_CELL_COORD)
 
 
+## docs/canonical-state.md:23 -- flags bit 0 is S.wrap.
+func test_decode_canon_header_reads_wrap_flag_bit() -> void:
+	var wrapped := PackedByteArray()
+	wrapped.resize(44)
+	wrapped.encode_u16(14, 1)
+	assert_bool(BoardGeometry.decode_canon_header(wrapped).wrap).is_true()
+
+	var walled := PackedByteArray()
+	walled.resize(44)
+	walled.encode_u16(14, 0)
+	assert_bool(BoardGeometry.decode_canon_header(walled).wrap).is_false()
+
+
 ## Operationalizes AC#4 (statement order matches snake.html's back-to-front
 ## layering) as a pinned data check rather than leaving it to code review.
 func test_draw_layer_order_matches_snake_htmls_back_to_front_layering() -> void:
 	assert_array(BoardGeometry.DRAW_LAYER_ORDER).is_equal([
-		"background", "checkerboard", "grid", "food", "snake", "eyes",
+		"background", "checkerboard", "grid", "walls", "food", "snake", "eyes",
 		"particles", "flash", "pause_vignette",
 	])
+
+
+## draw_rect's unfilled outline is centered on the boundary, so a
+## `thickness`-px border is inset by half its own width on every side.
+func test_wall_border_rect_is_inset_by_half_the_border_thickness() -> void:
+	var rect := BoardGeometry.wall_border_rect(24, 24, 20.0, 2.5)
+	assert_vector(rect.position).is_equal_approx(Vector2(1.25, 1.25), Vector2(0.0001, 0.0001))
+	assert_vector(rect.size).is_equal_approx(Vector2(477.5, 477.5), Vector2(0.0001, 0.0001))
+
+
+## One dash per perimeter cell: cols across the top + cols across the
+## bottom + rows down the left + rows down the right.
+func test_wall_dash_segments_has_one_dash_per_perimeter_cell() -> void:
+	var segments := BoardGeometry.wall_dash_segments(4, 3, 10.0, 2.0, 0.5)
+	assert_int(segments.size()).is_equal(2 * (4 + 3))
+
+
+## First dash is the top-left corner cell's own top edge, centered on that
+## cell and inset by half the border thickness -- same boundary line as
+## wall_border_rect's solid path.
+func test_wall_dash_segments_first_dash_sits_on_the_inset_top_edge() -> void:
+	var segments: Array = BoardGeometry.wall_dash_segments(4, 3, 10.0, 2.0, 0.5)
+	var first: Array = segments[0]
+	var from: Vector2 = first[0]
+	var to: Vector2 = first[1]
+	assert_float(from.y).is_equal_approx(1.0, 0.0001)
+	assert_float(to.y).is_equal_approx(1.0, 0.0001)
+	assert_float(from.x).is_equal_approx(2.5, 0.0001)
+	assert_float(to.x).is_equal_approx(7.5, 0.0001)
diff --git a/game/tests/test_content_loader.gd b/game/tests/test_content_loader.gd
index 5f98d13..824694f 100644
--- a/game/tests/test_content_loader.gd
+++ b/game/tests/test_content_loader.gd
@@ -38,6 +38,13 @@ func test_load_palette_from_the_real_content_file_succeeds() -> void:
 	var result := ContentLoaderScript.load_palette()
 	assert_bool(result.ok).is_true()
 	assert_str(result.data.ui.snake).is_equal("#4ade80")
+	assert_str(result.data.board.wall_border).is_equal("#e2e8f0")
+
+
+func test_load_tuning_from_the_real_content_file_includes_wall_border_tuning() -> void:
+	var result := ContentLoaderScript.load_tuning()
+	assert_bool(result.ok).is_true()
+	assert_float(result.data.render.wall_border_width_px).is_equal_approx(2.5, 0.0001)
 
 
 func test_load_modes_from_the_real_content_file_succeeds() -> void:
@@ -76,6 +83,17 @@ func test_wrong_field_type_reports_a_clear_error() -> void:
 	assert_str(result.error).contains("expected an array")
 
 
+func test_missing_wall_border_key_reports_a_clear_error() -> void:
+	var path := _write_temp("missing_wall_border.json", JSON.stringify({
+		"version": 1,
+		"ui": {"bg": "#0f172a", "panel": "#111c33", "grid_a": "#16233f", "grid_b": "#13203a", "snake": "#4ade80", "snake_head": "#a7f3d0", "food": "#f87171", "text": "#e2e8f0", "muted": "#7f8ea8", "accent": "#38bdf8"},
+		"board": {"background": "#0c1628", "checkerboard_tile": "#ffffff", "grid_line": "#38bdf8", "food_fill": "#ef4444", "food_shadow": "#f87171", "snake_head_fill": "#a7f3d0", "snake_head_shadow": "#4ade80", "snake_body_base_rgb": [74, 222, 128], "snake_body_rgb_delta": [30, -20, 30], "eye_fill": "#062c1a", "particle_hues": ["#f87171", "#fbbf24"], "flash_dead": "#ef4444", "flash_eat": "#fbbf24", "pause_vignette": "#060b16"},
+	}))
+	var result := ContentLoaderScript.load_palette(path)
+	assert_bool(result.ok).is_false()
+	assert_str(result.error).contains("missing required key 'wall_border'")
+
+
 func test_missing_file_reports_a_clear_error() -> void:
 	var result := ContentLoaderScript.load_tuning("res://content/does_not_exist.json")
 	assert_bool(result.ok).is_false()
@@ -89,7 +107,7 @@ func test_best_score_defaults_mismatched_with_modes_reports_a_clear_error() -> v
 		"flash": {"decay_per_ms": 0.004, "dead_alpha_factor": 0.28, "eat_alpha_factor": 0.12},
 		"food": {"pulse_period_ms": 260, "pulse_pad_base_fraction": 0.2, "pulse_pad_amplitude_fraction": 0.04, "shadow_blur_base_fraction": 0.7, "shadow_blur_amplitude_fraction": 0.6, "corner_radius_fraction": 0.28},
 		"snake": {"head_shadow_blur_fraction": 0.75, "body_pad_base_fraction": 0.12, "body_pad_amplitude_fraction": 0.16, "corner_radius_fraction": 0.3, "eye_side_offset_fraction": 0.19, "eye_forward_offset_fraction": 0.16, "eye_radius_fraction": 0.072, "eye_radius_min_px": 1.4},
-		"render": {"checkerboard_alpha": 0.019, "grid_line_alpha": 0.055, "device_pixel_ratio_cap": 2, "pause_vignette_alpha": 0.55},
+		"render": {"checkerboard_alpha": 0.019, "grid_line_alpha": 0.055, "device_pixel_ratio_cap": 2, "pause_vignette_alpha": 0.55, "wall_border_width_px": 2.5, "wall_border_alpha": 0.3, "wall_border_wrap_alpha": 0.1, "wall_border_wrap_dash_fraction": 0.55},
 		"input": {"swipe_threshold_cell_fraction": 0.5},
 		"scoring": {"best_score_defaults": {"wall": 0, "extra_mode": 0}},
 	}))
diff --git a/game/tests/test_game_screen.gd b/game/tests/test_game_screen.gd
index 606b8d5..47f4d43 100644
--- a/game/tests/test_game_screen.gd
+++ b/game/tests/test_game_screen.gd
@@ -120,6 +120,20 @@ func test_hud_reflects_score_and_status_after_start() -> void:
 	assert_str(_screen.hud._status_label.text).is_equal(GameScreenState.SCREEN_PLAYING.capitalize())
 
 
+## project.godot's viewport_height is 545 with a 520x520 board, leaving a
+## 25px strip for the HUD -- it must fit inside that, not spill below it.
+func test_hud_fits_inside_the_25px_strip_below_the_board() -> void:
+	assert_float(_screen.hud.custom_minimum_size.y).is_less_equal(25.0)
+	assert_float(_screen.hud.position.y + _screen.hud.custom_minimum_size.y).is_less_equal(545.0)
+
+
+## Quit (added for the title screen) reuses _quit_game() -- the same
+## music.stop()-then-quit path _notification() already runs on window
+## close -- rather than calling get_tree().quit() from a second place.
+func test_overlay_quit_requested_is_wired_to_quit_game() -> void:
+	assert_bool(_screen.overlay.quit_requested.is_connected(_screen._quit_game)).is_true()
+
+
 func test_start_or_restart_plays_the_start_cue() -> void:
 	_screen._start_or_restart()
 	assert_bool(_screen.sfx._players["start"].playing).is_true()
diff --git a/game/tests/test_game_screen_state.gd b/game/tests/test_game_screen_state.gd
index ed57b01..39f1f13 100644
--- a/game/tests/test_game_screen_state.gd
+++ b/game/tests/test_game_screen_state.gd
@@ -83,3 +83,16 @@ func test_overlay_content_menu_and_paused_have_no_return_to_title() -> void:
 	for screen in [GameScreenState.SCREEN_MENU, GameScreenState.SCREEN_PAUSED]:
 		var content := GameScreenState.overlay_content(screen, 0, 0, 3, false)
 		assert_bool(content.show_return_to_title).is_false()
+
+
+## Only the menu offers Quit -- every other screen already has a way out
+## (Resume, Play Again, Return to Title).
+func test_overlay_content_menu_offers_quit() -> void:
+	var content := GameScreenState.overlay_content(GameScreenState.SCREEN_MENU, 0, 0, 3, false)
+	assert_bool(content.show_quit).is_true()
+
+
+func test_overlay_content_paused_and_dead_have_no_quit() -> void:
+	for screen in [GameScreenState.SCREEN_PAUSED, GameScreenState.SCREEN_DEAD]:
+		var content := GameScreenState.overlay_content(screen, 0, 0, 3, false)
+		assert_bool(content.show_quit).is_false()
diff --git a/game/tests/test_overlay_panel.gd b/game/tests/test_overlay_panel.gd
new file mode 100644
index 0000000..abafa10
--- /dev/null
+++ b/game/tests/test_overlay_panel.gd
@@ -0,0 +1,41 @@
+extends GdUnitTestSuite
+
+## Exercises OverlayPanel's configure()-driven visibility directly against
+## the real Control tree (no GameScreen needed), the way test_hud.gd would
+## if it existed -- the Quit button (added for the title-screen quit
+## option) is the only piece of overlay wiring this repo tests in
+## isolation rather than through test_game_screen.gd's end-to-end flow.
+
+var _overlay: OverlayPanel
+
+
+func before_test() -> void:
+	_overlay = OverlayPanel.new()
+	add_child(_overlay)
+
+
+func _menu_content() -> Dictionary:
+	return GameScreenState.overlay_content(GameScreenState.SCREEN_MENU, 0, 0, 3, false)
+
+
+func _paused_content() -> Dictionary:
+	return GameScreenState.overlay_content(GameScreenState.SCREEN_PAUSED, 0, 0, 3, false)
+
+
+func test_quit_button_is_visible_on_the_menu_by_default() -> void:
+	_overlay.configure(_menu_content())
+	assert_bool(_overlay._quit_button.visible).is_true()
+
+
+func test_quit_button_is_hidden_on_paused() -> void:
+	_overlay.configure(_paused_content())
+	assert_bool(_overlay._quit_button.visible).is_false()
+
+
+## A browser tab can't quit itself -- get_tree().quit() is a no-op there --
+## so game_screen.gd tells the overlay quit isn't available on web, and the
+## button must stay hidden even on the menu.
+func test_quit_button_stays_hidden_when_quit_is_unavailable() -> void:
+	_overlay.set_quit_available(false)
+	_overlay.configure(_menu_content())
+	assert_bool(_overlay._quit_button.visible).is_false()