feat: release spools time back up — thaw ramp on hand close, curved in-band thaw

Closing the hand no longer snaps to full speed: time ramps from where
it stood (near-zero out of a freeze, current slow-mo out of a thaw,
x1 out of realtime — depletion force-close gifts no slow-mo) up to x1
over release_thaw_s wall-clock seconds (default 0.5; 0 = snap).
Reopening mid-ramp cancels it. In-band thaw gains an acceleration
curve (thaw_curve, default 2.2): hangs slow longer, then rushes to
full speed, instead of linear.

Smoke gate: release must NOT be at x1 immediately after close (ramp
present) and must reach x1 within 3s; both modes covered. 3/3 green
on nh3-dev headless 4.7.1.

scripts/hand.gd

@@ -51,6 +51,12 @@ extends CanvasLayer
 @export var band_unavailable := 0.1
 ## Slowest thaw speed (time_scale at the top of the thaw band).
 @export var thaw_min_scale := 0.05
+## Closing the hand ramps time back to full speed over this many real
+## seconds instead of snapping (applies in both modes; 0 = snap).
+@export var release_thaw_s := 0.5
+## In-band thaw acceleration: 1 = linear; higher hangs slow longer,
+## then rushes to full speed.
+@export var thaw_curve := 2.2
 
 @export_group("KINETIC card")
 @export var kinetic_cost := 1
@@ -70,6 +76,8 @@ var hand_open := false
 var meter := 0.0
 var _hit_progress := 0
 var _last_ms := 0
+var _release_from := 1.0
+var _release_t := -1.0
 
 # Slot order is the hand: Q = slot 1, E = slot 2.
 var cards: Array[Dictionary] = []
@@ -123,6 +131,15 @@ func _process(_delta: float) -> void:
 		if meter_mode:
 			# Bands shift as the meter drains under an open hand.
 			_apply_time_state()
+
+	# Release ramp: after the hand closes, time spools back up to full
+	# speed on the wall clock instead of snapping.
+	if not hand_open and _release_t >= 0.0:
+		_release_t += real_dt
+		var k := clampf(_release_t / release_thaw_s, 0.0, 1.0)
+		Engine.time_scale = lerpf(_release_from, 1.0, k)
+		if k >= 1.0:
+			_release_t = -1.0
 	$HUD.queue_redraw()
 
 
@@ -165,6 +182,14 @@ func try_play(slot: int) -> void:
 
 
 func _set_open(open: bool) -> void:
+	if open:
+		_release_t = -1.0
+	elif release_thaw_s > 0.0:
+		# Spool up from wherever time stood: near-zero out of a freeze,
+		# the current slow-mo out of a thaw, x1 out of realtime (so a
+		# depletion force-close never gifts free slow-mo).
+		_release_from = thaw_min_scale if get_tree().paused else Engine.time_scale
+		_release_t = 0.0
 	hand_open = open
 	_apply_time_state()
 
@@ -173,7 +198,7 @@ func _apply_time_state() -> void:
 	var tree := get_tree()
 	if not hand_open:
 		tree.paused = false
-		Engine.time_scale = 1.0
+		Engine.time_scale = _release_from if _release_t >= 0.0 else 1.0
 		$Dim.visible = false
 		return
 	$Dim.visible = true
@@ -185,7 +210,7 @@ func _apply_time_state() -> void:
 			_set_dim(1.0)
 		elif f >= band_realtime:
 			tree.paused = false
-			var t := (band_thaw - f) / (band_thaw - band_realtime)
+			var t := pow((band_thaw - f) / (band_thaw - band_realtime), thaw_curve)
 			Engine.time_scale = clampf(t, thaw_min_scale, 1.0)
 			_set_dim(1.0 - t)
 		else:

tests/smoke.gd

@@ -124,11 +124,16 @@ func _test_hand(arena: Node, mech: CharacterBody2D) -> void:
 	if target.heat < target.heat_threshold:
 		_failures.append("HEAT x2 left target below threshold (heat %.1f)" % target.heat)
 
-	# Release: time resumes, the over-threshold grunt detonates.
+	# Release: the world unpauses into the spool-up ramp (not a snap),
+	# reaches full speed, and the over-threshold grunt detonates.
 	await _tap("hand_toggle")
-	if hand.hand_open or get_tree().paused or Engine.time_scale != 1.0:
+	if hand.hand_open or get_tree().paused:
 		_failures.append("hand did not close / world did not resume")
 		return
+	if hand.release_thaw_s > 0.0 and Engine.time_scale >= 1.0:
+		_failures.append("release snapped straight to full speed — no ramp")
+	if not await _until(func() -> bool: return Engine.time_scale >= 0.999, 3.0, "release ramp never reached full speed"):
+		return
 	for i in 10:
 		await get_tree().physics_frame
 	if is_instance_valid(target):
@@ -184,8 +189,9 @@ func _test_meter(hand: Node) -> void:
 		_failures.append("toggle mode at knob 0 did not open+pause")
 	await _tap("hand_toggle")
 	hand.meter_mode = true
-	if get_tree().paused or Engine.time_scale != 1.0:
-		_failures.append("world did not resume after toggle-mode close")
+	if get_tree().paused:
+		_failures.append("world stayed paused after toggle-mode close")
+	await _until(func() -> bool: return Engine.time_scale >= 0.999, 3.0, "toggle-mode release ramp never reached full speed")
 
 
 func _nearest_grunt(mech: CharacterBody2D) -> Node2D: