feat(buildings): ✨ Add adamantine_echo and resonance_chamber buildings, plus beacon_tower, resonance_wire, steam_track, and messenger_post improvements with updated treaty mechanics

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

public/resources/buildings/adamantine_echo.json

@@ -32,6 +32,10 @@
       {
         "type": "courier_delay_reduction",
         "value": -100
+      },
+      {
+        "type": "envelope_intercept_resistance",
+        "value": 0.5
       }
     ],
     "enables_units": [],

public/resources/buildings/resonance_chamber.json

@@ -28,6 +28,18 @@
       {
         "type": "science",
         "value": 2
+      },
+      {
+        "type": "comm_tier",
+        "value": 8
+      },
+      {
+        "type": "heartbeat_interval",
+        "value": 6
+      },
+      {
+        "type": "envelope_throughput",
+        "value": 2
       }
     ],
     "enables_units": [

public/resources/diplomacy/treaty_rules.json

@@ -51,6 +51,36 @@
       "breaks": "shared_map_single",
       "reputation_delta": 0,
       "description": "If the SharedMap courier is intercepted, the deal is voided but no reputation cost — both parties acted in good faith. Payment is non-refundable."
+    },
+    "envelope_intercepted_war_dec": {
+      "breaks": "pending_war_dec_overlay",
+      "reputation_delta": 0,
+      "single_attempt": true,
+      "description": "Communications Phase 2: an intercepted war-declaration envelope clears the sender's pending_war_dec overlay. The shared Relation does NOT flip (interception is functionally a failure to deliver the message). No third-party reputation hit — observers cannot tell the message was a war-dec. The sender takes a private reputation hit (-15, mc-comms domain) to mark broken trust without third-party diplomatic fallout."
+    },
+    "envelope_intercepted_peace_offer": {
+      "breaks": "peace_offer_single",
+      "reputation_delta": 0,
+      "single_attempt": true,
+      "description": "An intercepted peace-offer envelope simply fails to arrive. The sender can re-issue. No reputation impact."
+    },
+    "envelope_intercepted_joint_attack": {
+      "breaks": "joint_attack_plan_single",
+      "reputation_delta": 0,
+      "single_attempt": true,
+      "description": "An intercepted joint-attack envelope reveals the plan to whoever intercepted it (Phase 3 beacon-tap counter-intel will surface readable envelopes). The plan itself is voided; no reputation cost to sender."
+    },
+    "envelope_intercepted_research_agreement": {
+      "breaks": "research_payout_single",
+      "reputation_delta": 0,
+      "single_attempt": true,
+      "description": "A research-agreement payout envelope intercepted in transit forfeits that tick's beaker transfer. The underlying agreement remains active."
+    },
+    "envelope_intercepted_tribute": {
+      "breaks": "tribute_demand_single",
+      "reputation_delta": 0,
+      "single_attempt": true,
+      "description": "An intercepted tribute-demand envelope fails to arrive — the demand is silently void. Sender can re-issue."
     }
   },
   "edge_cases": [

public/resources/improvements/beacon_tower.json

@@ -11,7 +11,10 @@
   "effects": {
     "vision_bonus": 2,
     "provides_los_chain": true,
-    "severable": false
+    "severable": false,
+    "comm_tier": 6,
+    "los_chain": true,
+    "decay_radius_mult": 1.5
   },
   "hp": 35,
   "flags": ["destroyable_structure", "courier_infrastructure"],

public/resources/improvements/messenger_post.json

@@ -0,0 +1,23 @@
+{
+  "id": "messenger_post",
+  "name": "Messenger Post",
+  "description": "A road-side waystation with stabled couriers, signal-flags, and a small lookout. Early-era infrastructure that lets foot-couriers run a step faster than the open trail allows. Cheap, available before tunnels or beacons, and adjacent-to-road only.",
+  "build_turns": 4,
+  "valid_terrain": "any_land",
+  "adjacency_required": ["road", "hold_road"],
+  "requires_tech": "roads",
+  "yields": {},
+  "effects": {
+    "comm_tier": 2,
+    "comm_steps_per_turn_bonus": 1,
+    "severable": false
+  },
+  "cost": 30,
+  "flags": ["courier_infrastructure", "early_courier"],
+  "encyclopedia": {
+    "category": "civilization",
+    "entry_type": "improvement",
+    "detail_route": "/buildings/improvements",
+    "tags": ["courier", "infrastructure", "era2"]
+  }
+}

public/resources/improvements/resonance_wire.json

@@ -8,7 +8,10 @@
   "yields": {},
   "effects": {
     "courier_delay_class": "near_instant",
-    "severable": true
+    "severable": true,
+    "comm_tier": 8,
+    "vision_share_latency": 0,
+    "decay_radius_mult": 2.5
   },
   "encyclopedia": {
     "category": "civilization",

public/resources/improvements/steam_track.json

@@ -8,7 +8,10 @@
   "yields": {},
   "effects": {
     "movement_cost_modifier": -2,
-    "severable": true
+    "severable": true,
+    "comm_tier": 7,
+    "vision_share_latency": 1,
+    "decay_radius_mult": 2.0
   },
   "encyclopedia": {
     "category": "civilization",