feat(audio): Sprint 13 — AudioManager, zone crossfade, dip profiles, murmur wiring (#528, #529, #530, #533)

AudioManager: volume slider persistence (ConfigFile), settings UI with
5 teal-bordered sliders, default_bus_layout.tres for editor. Zone
crossfade: defensive zone_id read from snapshot tiles, 1.5-2s ambient
tween, auto-activates when server ships OQ-09. Dip profiles: dialogue
dip in show/hide_dialogue, ListeningFocus 30-tick gate via
stationary_ticks in game_state.gd. NPC murmur: client plumbing for
event-driven World SFX playback, no-ops until audio asset arrives.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/autoloads/audio_manager.gd

@@ -41,6 +41,18 @@ const DIP_SPECS := {
 # Low-pass filter default cutoff — effectively bypassed at this value.
 const FILTER_CUTOFF_DEFAULT := 20500.0
 
+# --- D-073: Zone crossfade constants ---
+const CROSSFADE_DURATION := 1.8  # D-073: 1.5-2s spec, mid-range
+
+# Maps server zone_id strings to ambient asset keys (filenames in res://audio/).
+# Hub and Workplace share the same ambient layer — same location type.
+const ZONE_ASSETS: Dictionary = {
+	"hub":       "amb_hub_layer",
+	"workplace": "amb_hub_layer",
+	"bar":       "amb_bar_layer",
+	"corridor":  "amb_corridor_layer",
+}
+
 # Asset registry: filename stem (e.g. "amb_station_base") → AudioStream
 var _registry: Dictionary = {}
 
@@ -57,12 +69,19 @@ var _ambient_filter: AudioEffectLowPassFilter = null
 # Ambient loop players keyed by asset_key (D-073 zone crossfade)
 var _ambient_players: Dictionary = {}
 
+# D-073: Zone crossfade state
+var _current_zone_id: String = ""
+var _zone_tweens: Array = []
+
 signal dip_changed(profile: String)
 
 
+const PREFS_PATH := "user://audio_prefs.cfg"
+
 func _ready() -> void:
 	_setup_buses()
 	_scan_registry()
+	_load_prefs()
 
 
 # --- Bus setup ---
@@ -173,9 +192,8 @@ func stop_all_loops() -> void:
 # --- Audio asset registry: event type → asset key (D-018, #125) ---
 # Maps server-sent sound event_type strings to audio asset keys.
 # Keys match filename stems in res://audio/ (scanned by _scan_registry).
-# Audio assets per D-038: footstep variants (walk / run).
-# No asset for Voice events in v0.1 — play_sound_event no-ops gracefully
-# (D-038: "renders as audio if asset exists, or visual indicator + monologue if not").
+# Audio assets per D-038: footstep variants (walk / run), NPC murmur (D-072, #532).
+# Missing assets no-op gracefully (D-038 fallback pattern).
 const SOUND_EVENT_ASSETS: Dictionary = {
 	"Footstep":       "sfx_footstep_metal_walk",
 	"FootstepWalk":   "sfx_footstep_metal_walk",
@@ -183,6 +201,10 @@ const SOUND_EVENT_ASSETS: Dictionary = {
 	"FootstepCrouch": "sfx_footstep_metal_walk",  # D-053: same asset until stance-differentiated audio lands
 	"FootstepSprint": "sfx_footstep_metal_run",
 	"FootstepRun":    "sfx_footstep_metal_run",
+	# D-072 (#533): NPC conversation murmur — single universal asset, World SFX bus.
+	# Zone ambient provides natural conspicuousness (bar buries it, corridor exposes it).
+	"Voice":          "sfx_npc_murmur",
+	"VoiceConversation": "sfx_npc_murmur",
 }
 
 
@@ -304,19 +326,85 @@ func set_volume(bus: String, volume_db: float) -> void:
 		var buses: Dictionary = spec.get("buses", {})
 		var offset_db: float = buses.get(bus, 0.0)
 		AudioServer.set_bus_volume_db(idx, volume_db + offset_db)
+	_save_prefs()
 
 
 func get_volume(bus: String) -> float:
 	return _bus_volumes.get(bus, 0.0)
 
 
-# --- Zone crossfade (D-073 stub) ---
+# --- Volume persistence (user://audio_prefs.cfg) ---
+
+func _load_prefs() -> void:
+	var cfg := ConfigFile.new()
+	if cfg.load(PREFS_PATH) != OK:
+		return
+	for bus_name in BUSES:
+		if cfg.has_section_key("audio", bus_name):
+			var db: float = cfg.get_value("audio", bus_name, 0.0)
+			# Apply directly: bypass _save_prefs() on initial load.
+			_bus_volumes[bus_name] = db
+			var idx := AudioServer.get_bus_index(bus_name)
+			if idx >= 0:
+				AudioServer.set_bus_volume_db(idx, db)
+
+
+func _save_prefs() -> void:
+	var cfg := ConfigFile.new()
+	for bus_name in BUSES:
+		cfg.set_value("audio", bus_name, _bus_volumes.get(bus_name, 0.0))
+	var err := cfg.save(PREFS_PATH)
+	if err != OK:
+		push_warning("AudioManager: failed to save prefs to %s (error %d)" % [PREFS_PATH, err])
+
+
+# --- Zone crossfade (D-073) ---
 
 ## Handle zone transition. Server sends zone_id per tile in ObserverSnapshot.
-## Full crossfade implementation deferred to Sprint 9+ (D-073).
-## Stub exists so server integration can call it without conditional checks.
-func set_zone(_zone_id: String) -> void:
-	pass
+## Hard boundary trigger with 1.5-2s audio crossfade between ambient layers.
+## Interruptible — mid-crossfade zone change tweens from current position.
+## No-op if assets absent (D-038) or same zone.
+func set_zone(zone_id: String) -> void:
+	if zone_id == _current_zone_id:
+		return
+	var new_asset: String = ZONE_ASSETS.get(zone_id, "")
+	var old_asset: String = ZONE_ASSETS.get(_current_zone_id, "")
+	_current_zone_id = zone_id
+	_kill_zone_tweens()
+
+	# Fade out old ambient layer (if different asset from incoming zone)
+	if not old_asset.is_empty() and old_asset != new_asset:
+		if _ambient_players.has(old_asset):
+			var old_player: AudioStreamPlayer = _ambient_players[old_asset]
+			if is_instance_valid(old_player):
+				var tween := create_tween()
+				tween.tween_property(old_player, "volume_db", -80.0, CROSSFADE_DURATION)
+				tween.tween_callback(stop_loop.bind(old_asset))
+				_zone_tweens.append(tween)
+
+	# Fade in new ambient layer
+	if not new_asset.is_empty():
+		if _ambient_players.has(new_asset):
+			# Already playing (interrupted reverse crossfade) — tween from current volume
+			var existing: AudioStreamPlayer = _ambient_players[new_asset]
+			if is_instance_valid(existing):
+				var tween := create_tween()
+				tween.tween_property(existing, "volume_db", 0.0, CROSSFADE_DURATION)
+				_zone_tweens.append(tween)
+		elif has_asset(new_asset):
+			var new_player := play_loop(new_asset, BUS_AMBIENT)
+			if new_player:
+				new_player.volume_db = -80.0
+				var tween := create_tween()
+				tween.tween_property(new_player, "volume_db", 0.0, CROSSFADE_DURATION)
+				_zone_tweens.append(tween)
+
+
+func _kill_zone_tweens() -> void:
+	for tween in _zone_tweens:
+		if tween != null and tween.is_valid():
+			tween.kill()
+	_zone_tweens.clear()
 
 
 # --- Internal helpers ---

client/scripts/autoloads/game_state.gd

@@ -62,6 +62,12 @@ var medium_sound_events: Array = []
 # Format: [{x, y, event_type, range_category}] — consumed once per tick in main.gd.
 var close_sound_events: Array = []
 
+# D-071 (#530): Consecutive ticks without player position change.
+# Incremented per snapshot in apply_snapshot(). Reset to 0 on movement.
+# ListeningFocus boost activates at 30+ ticks (main.gd manages the dip).
+var stationary_ticks: int = 0
+var _prev_player_position: Vector2 = Vector2(-1e9, -1e9)  # sentinel: no previous position
+
 func apply_snapshot(snapshot: Dictionary) -> void:
 	current_snapshot = snapshot
 
@@ -83,6 +89,14 @@ func apply_snapshot(snapshot: Dictionary) -> void:
 			push_warning("GameState: no Player entity found in %d entities" % [
 				visible_entities.size()])
 
+	# D-071 (#530): Track consecutive stationary ticks for ListeningFocus boost.
+	# Compares current player_position against previous snapshot's position.
+	if player_position == _prev_player_position:
+		stationary_ticks += 1
+	else:
+		stationary_ticks = 0
+	_prev_player_position = player_position
+
 	# Tiles for rendering: test mode sends "tiles", live server sends tile data in "visible_tiles"
 	if snapshot.has("tiles"):
 		visible_tiles = snapshot.tiles

client/scripts/main.gd

@@ -15,6 +15,7 @@ extends Node2D
 @onready var gauntlet_hud = $UILayer/GauntletHUD  # #496: room timer + personal bests
 @onready var checklist_overlay = $UILayer/ChecklistOverlay  # #503: auto-checklist progress
 @onready var bug_report_dialog = $ModalLayer/BugReportDialog  # #495: F12 WRONG button
+@onready var settings_dialog = $ModalLayer/SettingsDialog     # #528: audio settings (ESC/OPEN_MENU)
 
 var _last_dialogue_npc_id: int = -1  # D-064: NPC entity_id for WalkAway input
 var _camera_anchored: bool = false
@@ -24,6 +25,9 @@ var _known_recognition_ids: Dictionary = {}  # D-067: entity_ids that have alrea
 var _flash_rect: ColorRect = null  # #502/#501: ephemeral screen flash overlay (shared: teleport preempts amber)
 var _teleport_in_progress: bool = false  # #501: defer smoothing re-enable by one frame after teleport
 var _pending_record_inputs: Array = []   # #507: accumulates server-bound inputs across frames; flushed into record_tick() on snapshot arrival
+var _current_zone: String = ""           # D-073 (#529): zone tracking for ambient crossfades
+
+const LISTENING_FOCUS_TICKS: int = 30  # D-071: stationary ticks before ListeningFocus boost activates
 
 func _ready() -> void:
 	print("The Settled Reach — client initialized")
@@ -128,6 +132,13 @@ func _process(_delta: float) -> void:
 		# D-018 #125: Play close-range sound events via positional 2D audio
 		_play_close_sound_events()
 
+		# D-073 (#529): Zone ambient crossfade — detect player tile zone, trigger set_zone on change.
+		_update_zone()
+
+		# D-071 (#530): ListeningFocus boost — stationary 30+ ticks boosts WorldSFX.
+		# Only activates when no dialogue/confrontation dip is active (D-070).
+		_update_listening_focus()
+
 		# Show monologue if server sent one this tick (#414)
 		_consume_monologue()
 
@@ -162,6 +173,14 @@ func _process(_delta: float) -> void:
 			if bug_report_dialog and not bug_report_dialog.is_active():
 				bug_report_dialog.start_capture()
 			continue
+		# #528: ESC/OPEN_MENU — client-only, toggle audio settings dialog
+		if input.action == InputMapper.Action.OPEN_MENU:
+			if settings_dialog:
+				if settings_dialog.is_open():
+					settings_dialog.close()
+				else:
+					settings_dialog.open()
+			continue
 		if input.action == InputMapper.Action.INTERACT:
 			# D-057: prefer interaction list (multi-verb), fall back to prompt (v0.1)
 			var target_id: int = -1
@@ -235,6 +254,38 @@ func _play_recognition_chimes() -> void:
 			_known_recognition_ids.erase(eid)
 
 
+# D-073 (#529): Zone ambient crossfade — read zone_id from player's current tile.
+# Calls AudioManager.set_zone() when zone changes (AudioManager handles crossfade).
+# zone_id field is server-authoritative; missing field treated as empty (no zone).
+func _update_zone() -> void:
+	var px := int(GameState.player_position.x)
+	var py := int(GameState.player_position.y)
+	var zone: String = ""
+	for tile in GameState.visible_tiles:
+		if not tile is Dictionary:
+			continue
+		if tile.get("x") == px and tile.get("y") == py:
+			zone = tile.get("zone_id", "")
+			break
+	if zone != _current_zone:
+		_current_zone = zone
+		AudioManager.set_zone(zone)
+
+
+# D-071 (#530): ListeningFocus boost — World SFX +2.5dB when stationary 30+ ticks.
+# Uses AudioManager.get_active_dip() as single source of truth (no separate flag).
+# Only activates when no other dip (dialogue/confrontation) is running.
+# Only deactivates its own dip — never touches dialogue/confrontation.
+# D-070: no UI indicator — the boost is "felt, not computed."
+func _update_listening_focus() -> void:
+	var current_dip := AudioManager.get_active_dip()
+	var threshold_met := GameState.stationary_ticks >= LISTENING_FOCUS_TICKS
+	if threshold_met and current_dip == "":
+		AudioManager.apply_dip("listening_focus")
+	elif not threshold_met and current_dip == "listening_focus":
+		AudioManager.clear_dip()
+
+
 # Consume-once per tick: show monologue text, then clear.
 # Tick guard prevents re-triggering when the same tick is polled multiple
 # times (client FPS > sim tick rate).