Phase 11 — Day/night cycle + Lighting (taken before Phase 9 per recommendation)

Three gdscript-refactor agents in parallel; Opus integrated and verified
the day-night transition + torch lighting via MCP runtime + screenshot.

Clock autoload (Agent A, autoload/clock.gd, ~138 lines):
- TICKS_PER_DAY = 4800 → 4 min/day at 1× / 48 s at Fast / 20 s at Ultra
- TICKS_PER_HOUR = 200 (so 60 min × ~3 ticks per minute)
- 4-phase day: night → dawn (5–7) → day (7–19) → dusk (19–22) → night
- darkness_factor() returns 0..1 with linear ramps across dawn/dusk
- phase_changed signal fires on phase transitions
- save_dict / apply_dict for save round-trip
- Boots at Day 1, 06:00 (mid-dawn for atmospheric start)
- Registered in project.godot autoload list (Opus)

Top-bar clock UI (Agent A):
- ClockLabel added to top_bar.tscn (center-anchored at ±80 px)
- _on_clock_refresh in top_bar.gd; early-out string compare to skip text
  assignments when unchanged (cheap per-tick)

Torch entity + lights registry (Agent B, scenes/entities/torch.{gd,tscn} +
workbench.gd + world.gd, ~210 lines):
- class Torch: buildable furniture, BUILD_TICKS=30, LIGHT_RADIUS=6
- Procedural radial gradient texture (64×64) generated at runtime with
  smoothstep falloff → no PNG dependency
- PointLight2D child with the gradient texture, warm fire tint, energy 1.2
- is_on / get_light_tile / get_light_radius duck-typed interface; same
  shape exposed by Workbench when label_text='Hearth' (HEARTH_LIGHT_RADIUS=5)
- World.light_sources registry + register/unregister + is_tile_lit(tile)
  (Manhattan distance, no occlusion — Phase 13 may add wall-occlusion)

CanvasModulate darkness + in_darkness thought (Agent C, ~30 lines mod +
new factory):
- DarkOverlay CanvasModulate node added to world.tscn (first child of
  World root so it tints all sibling layers + entities)
- world.gd._update_dark_overlay lerps DAY_TINT (white) ↔ NIGHT_TINT
  (0.20, 0.22, 0.40 deep cool blue) by Clock.darkness_factor() each tick
- ThoughtCatalog.in_darkness(): persistent, -3 mood, fires when
  darkness > 0.3 AND World.is_tile_lit(pawn.tile) is false
- Pawn._process_thoughts syncs in_darkness alongside hungry/tired

Opus integration:
- project.godot: Clock autoload registered
- world.tscn: DarkOverlay CanvasModulate node, plus the agent additions
- Demo seed: 2 torches inside cabin at (46, 26) + (49, 26), pre-built
- MCP-driven runtime test verified day→night transition + lighting
  effects:
  - Noon: world bright green, torches barely visible (over-bright at noon
    is minor polish — Phase 17 may scale torch energy by darkness)
  - Midnight: world deep blue/green tinted, torches cast yellow halos,
    Hearth ember glows orange, cabin interior warmly lit, exterior dark
- top_bar clock label updates each sim tick (early-out on no-change)

Phase 11 followups for later phases:
- Torch energy should scale with darkness — visible halos at noon are
  silly. Phase 17 will likely tie PointLight2D.energy to clamp(darkness,
  0.2, 1.0) so they're invisible at midday
- Wall-occlusion for light_map — Phase 13's room-detection BFS could
  treat completed wall tiles as occluders so light doesn't bleed through
- 'In darkness' thought currently treats ALL unlit cells as darkness;
  Phase 13's roof flag could differentiate 'indoors-dark' (different
  thought) from 'outdoors-dark'
- Light source visibility through CanvasModulate works correctly thanks
  to PointLight2D's additive blend mode

Acceptance — MCP-verified via play_scene + get_game_screenshot:
- ✅ Day → Dusk → Night cycle visible (Clock.current_phase emits events)
- ✅ CanvasModulate tints world deep blue at night
- ✅ Torches cast visible yellow halos via PointLight2D additive blend
- ✅ Hearth opts-in as a light source via label_text='Hearth' check
- ✅ Top-bar clock shows 'Day N, HH:MM' format and updates each tick
- ✅ in_darkness thought wires through _process_thoughts (would fire if
  a pawn were standing in an unlit night tile — demo didn't capture this
  specifically but the code path is verified)

Delegation report this phase:
- Agent A: Clock autoload + 4-phase day cycle + top-bar UI extension
- Agent B: Torch entity + PointLight2D + procedural radial texture +
  Workbench Hearth opt-in + World.light_sources registry
- Agent C: CanvasModulate world.tscn node + day/night colour lerp +
  in_darkness ThoughtCatalog entry + Pawn persistent thought sync
- Opus: Clock autoload registration in project.godot + 2 torches in
  demo seed + MCP runtime verification at midnight vs noon

~75% of Phase 11 GDScript was subagent-authored.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

autoload/world.gd

@@ -54,6 +54,13 @@ var crops: Array = []
 # Storyteller also reads beds.size() for the "First Beds" state predicate.
 var beds: Array = []
 
+# Phase 11 — light-source entities (Torch + Hearth workbench). Entities call
+# register_light_source() in _ready and unregister_light_source() in _exit_tree.
+# is_tile_lit() is queried by the "in darkness" thought and any future
+# darkness-rendering shader bridge. All entries expose the duck-type interface:
+#   is_on() → bool | get_light_tile() → Vector2i | get_light_radius() → int
+var light_sources: Array = []
+
 # Phase 4 — hauling dirty set. Keys are Items, value is unused (we just use .keys()).
 # An Item is added when it spawns (Tree.fell, Rock.mined, workbench drop, ...)
 # and removed when it lands at its highest-priority valid destination.
@@ -193,6 +200,33 @@ func unregister_bed(b) -> void:
 	beds.erase(b)
 
 
+# ── Phase 11: light-source registry ────────────────────────────────────────
+
+func register_light_source(ls) -> void:
+	if not light_sources.has(ls):
+		light_sources.append(ls)
+
+
+func unregister_light_source(ls) -> void:
+	light_sources.erase(ls)
+
+
+## Returns true if `tile` is within get_light_radius() of any is_on() light
+## source. Uses Manhattan distance (no wall-occlusion in Phase 11; Phase 13
+## may add BFS-based occlusion through the room/roof system).
+##
+## Called by the "in darkness" Thought trigger on each pawn sim tick.
+## O(light_sources) per call; trivial at our scale (< 50 sources in MVP).
+func is_tile_lit(p_tile: Vector2i) -> bool:
+	for ls in light_sources:
+		if not ls.is_on():
+			continue
+		var d: int = abs(ls.get_light_tile().x - p_tile.x) + abs(ls.get_light_tile().y - p_tile.y)
+		if d <= ls.get_light_radius():
+			return true
+	return false
+
+
 # Called by Wall.on_build_tick() when construction completes.
 # Stamps the data-only Wall TileMap layer so room/roof/save logic sees the
 # wall. World scene exposes wall_layer via a getter set during _ready.