worldmarkers: locale-safe coordinate encoding, clear markers on group leave

Addon messages now encode coordinates as integers (*1000) to avoid
locale-dependent decimal separators breaking cross-client sync.

DLL detects group leave via LEADER_GUID dropping to zero and clears
all markers locally -- no addon permission checks needed.

src/worldmarkers/addon/WorldMarkers.lua

@@ -82,11 +82,16 @@ end
 -- Broadcast helpers
 -- =============================================================================
 
+-- Encode floats as integers (*1000) to avoid locale-dependent decimal separators.
+-- Receivers divide by 1000. Sub-millimeter precision loss is irrelevant for markers.
+local function encodeCoord(v) return math.floor(v * 1000) end
+local function decodeCoord(v) return v / 1000 end
+
 local function broadcastPlace(index, x, y, z, areaId)
     clearSyncState()
     local ch = getChannel()
     if not ch then return end
-    local msg = "P:" .. index .. ":" .. x .. ":" .. y .. ":" .. z .. ":" .. areaId
+    local msg = "P:" .. index .. ":" .. encodeCoord(x) .. ":" .. encodeCoord(y) .. ":" .. encodeCoord(z) .. ":" .. areaId
     SendAddonMessage(MSG_PREFIX, msg, ch)
 end
 
@@ -111,7 +116,7 @@ local function broadcastAllDefs()
     for i = 1, NUM_MARKERS do
         local x, y, z, areaId = GetWorldMarker(i)
         if x then
-            local msg = "SF:" .. i .. ":" .. x .. ":" .. y .. ":" .. z .. ":" .. areaId
+            local msg = "SF:" .. i .. ":" .. encodeCoord(x) .. ":" .. encodeCoord(y) .. ":" .. encodeCoord(z) .. ":" .. areaId
             SendAddonMessage(MSG_PREFIX, msg, ch)
         end
     end
@@ -220,7 +225,7 @@ local function parseMarkerFields(parts)
     local z = tonumber(parts[5])
     local areaId = tonumber(parts[6])
     if idx and x and y and z and areaId then
-        return idx, x, y, z, areaId
+        return idx, decodeCoord(x), decodeCoord(y), decodeCoord(z), areaId
     end
     return nil
 end

src/worldmarkers/worldmarkers.zig

@@ -103,6 +103,9 @@ const RESPAWN_CHECK_INTERVAL_MS: u32 = 1000;
 var last_zombie_tick: u32 = 0;
 const ZOMBIE_CHECK_INTERVAL_MS: u32 = 3000;
 
+// Group-leave detection: clear markers when player drops to solo.
+var was_in_group: bool = false;
+
 // Entities playing their Decay animation before destruction.
 // Cleaned up every frame by tickAnimations (via OnWorldUpdate hook).
 const MAX_DESPAWNING = 8;
@@ -541,6 +544,15 @@ const HOLD_QUEUE_DELAY_MS: u32 = 2000;
 fn tickAnimations() void {
     const now = GetTickCount();
 
+    // Group-leave detection: leader GUID is set for both party and raid.
+    // When it drops to zero the player left the group — clear all markers.
+    const in_group = wow.readGUID(o.LEADER_GUID) != 0;
+    if (was_in_group and !in_group) {
+        log.print("left group, clearing all markers\n");
+        clearAllMarkers();
+    }
+    was_in_group = in_group;
+
     cleanupDespawning();
 
     // Queue Hold animation for freshly-created markers