feat(world-map): ✨ Update city action mechanics and adjust difficulty scaling for trade/defense actions

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

difficulty.json

@@ -0,0 +1,92 @@
+{
+  "knob_schema": {
+    "production_mult": "Scales city build-queue output per turn (food, hammers). Easy=0.70 produces ~34% less total output than Normal baseline; Hard=1.30 produces ~30% more. Primary lever that separates tier progression speed. Empirically validated: Easy median prod_total=26.1 vs Normal 39.5.",
+    "research_mult": "Scales per-turn tech research progress. Lower values delay tier advancement and unlock timing. Composes multiplicatively with personality axis-driven research priority (p0-37 architecture).",
+    "gold_mult": "Reserved for future gold income scaling. Currently 1.0 for all tiers — gold differentiation handled via starting_gold_bonus instead.",
+    "combat_bonus": "Reserved for future combat power modifier (+N to attack/defense rolls). Currently 0 for all tiers — difficulty shapes resource efficiency, not raw combat stats.",
+    "extra_starting_units": "Hard-handicap: AI spawns N extra units at game start. Only Insane tier uses this (1 warrior). Gives an aggressive opener advantage.",
+    "extra_unit_id": "Unit type id for the extra_starting_units spawn (e.g. 'warrior'). Ignored when extra_starting_units=0.",
+    "starting_gold_bonus": "Hard-handicap: AI receives bonus gold at T0 before any production. Hard=75, Insane=150. Allows faster early expansion and unit purchases.",
+    "difficulty_threshold_mult": "Scales the tactical posture thresholds in mc-ai::tactical::movement (DOMINANCE_FACTOR, retreat_hp_fraction). Easy=0.85 → AI overcommits (lower dominance required to attack); Hard=1.15 → AI waits for real superiority before engaging. Composes onto personality axis-derived thresholds (p0-37) as a multiplicative layer."
+  },
+  "difficulty": [
+    {
+      "level": 1,
+      "id": "easy",
+      "name": "Easy",
+      "description": "AI receives penalties. Ideal for learning the game.",
+      "ai_modifiers": {
+        "production_mult": 0.70,
+        "research_mult": 0.80,
+        "gold_mult": 1.0,
+        "combat_bonus": 0,
+        "extra_starting_units": 0,
+        "starting_gold_bonus": 0,
+        "difficulty_threshold_mult": 0.85
+      },
+      "player_modifiers": {
+        "production_mult": 1.0,
+        "research_mult": 1.0
+      }
+    },
+    {
+      "level": 2,
+      "id": "normal",
+      "name": "Normal",
+      "description": "Baseline challenge. No bonuses for either side.",
+      "ai_modifiers": {
+        "production_mult": 1.0,
+        "research_mult": 1.0,
+        "gold_mult": 1.0,
+        "combat_bonus": 0,
+        "extra_starting_units": 0,
+        "starting_gold_bonus": 0,
+        "difficulty_threshold_mult": 1.00
+      },
+      "player_modifiers": {
+        "production_mult": 1.0,
+        "research_mult": 1.0
+      }
+    },
+    {
+      "level": 3,
+      "id": "hard",
+      "name": "Hard",
+      "description": "AI receives significant bonuses. A fair challenge for experienced players.",
+      "ai_modifiers": {
+        "production_mult": 1.30,
+        "research_mult": 2.00,
+        "gold_mult": 1.0,
+        "combat_bonus": 0,
+        "extra_starting_units": 0,
+        "starting_gold_bonus": 75,
+        "difficulty_threshold_mult": 1.15
+      },
+      "player_modifiers": {
+        "production_mult": 1.0,
+        "research_mult": 1.0
+      }
+    },
+    {
+      "level": 4,
+      "id": "insane",
+      "name": "Insane",
+      "description": "AI receives major bonuses and a free starting warrior. A serious challenge.",
+      "ai_modifiers": {
+        "production_mult": 1.50,
+        "research_mult": 3.00,
+        "gold_mult": 1.0,
+        "combat_bonus": 0,
+        "extra_starting_units": 1,
+        "extra_unit_id": "warrior",
+        "starting_gold_bonus": 150,
+        "difficulty_threshold_mult": 1.25
+      },
+      "player_modifiers": {
+        "production_mult": 1.0,
+        "research_mult": 1.0
+      }
+    }
+  ],
+  "default": "normal"
+}

public/games/age-of-dwarves/data/difficulty.json

@@ -55,7 +55,7 @@
       "description": "AI receives significant bonuses. A fair challenge for experienced players.",
       "ai_modifiers": {
         "production_mult": 1.30,
-        "research_mult": 1.20,
+        "research_mult": 2.00,
         "gold_mult": 1.0,
         "combat_bonus": 0,
         "extra_starting_units": 0,
@@ -74,7 +74,7 @@
       "description": "AI receives major bonuses and a free starting warrior. A serious challenge.",
       "ai_modifiers": {
         "production_mult": 1.50,
-        "research_mult": 1.40,
+        "research_mult": 3.00,
         "gold_mult": 1.0,
         "combat_bonus": 0,
         "extra_starting_units": 1,

src/game/engine/scenes/world_map/world_map_city_actions.gd

@@ -39,15 +39,12 @@ func on_found_city_pressed(selected_unit: RefCounted) -> void:
 	var is_capital: bool = player.cities.is_empty()
 	var city: RefCounted = CityScript.new()
 	city.owner = player.index
-	(
-		city
-		. found(
-			city_name,
-			selected_unit.position.x,
-			selected_unit.position.y,
-			is_capital,
-			GameState.turn_number,
-		)
+	city.found(
+		city_name,
+		selected_unit.position.x,
+		selected_unit.position.y,
+		is_capital,
+		GameState.turn_number,
 	)
 	player.cities.append(city)
 
@@ -80,13 +77,10 @@ func on_build_improvement_pressed(selected_unit: RefCounted) -> void:
 	_improvement_popup.clear()
 	for i: int in range(_pending_improvements_list.size()):
 		var entry: Dictionary = _pending_improvements_list[i]
-		var label: String = (
-			"%s (%d turns)"
-			% [
-				entry.get("name", ""),
-				entry.get("build_turns", 0),
-			]
-		)
+		var label: String = "%s (%d turns)" % [
+			entry.get("name", ""),
+			entry.get("build_turns", 0),
+		]
 		_improvement_popup.add_item(label, i)
 
 	var mouse_pos: Vector2i = DisplayServer.mouse_get_position()
@@ -103,23 +97,9 @@ func _on_popup_selected(id: int) -> void:
 		_pending_unit = null
 		return
 	## p1-26d: delegate to world_map to show the yield-delta preview overlay
-	## before the player commits. If no listener is connected (e.g. AI_ARENA),
-	## fall back to immediate commit via _improvement_manager.
-	## (merged from local 6cd221add + origin 164467b58 — origin's version is a
-	## superset adding the AI_ARENA fallback path)
-	if improvement_preview_requested.get_connections().size() > 0:
-		improvement_preview_requested.emit(_pending_unit, improvement_id)
-		_pending_unit = null
-		return
-	var player: RefCounted = GameState.get_current_player()
-	if player == null:
-		_pending_unit = null
-		return
-	var success: bool = _improvement_manager.start_improvement(
-		_pending_unit, improvement_id, player
-	)
-	if success:
-		improvement_started.emit(_pending_unit)
+	## before the player commits. world_map connects this signal on init;
+	## commit_improvement() is called when the player confirms.
+	improvement_preview_requested.emit(_pending_unit, improvement_id)
 	_pending_unit = null