fix: preserve capture geoip override

.changeset/calm-bees-smile.md

@@ -0,0 +1,5 @@
+---
+'PostHog': patch
+---
+
+Preserve per-capture GeoIP override properties when super properties are configured.

src/PostHog/PostHogClient.cs

@@ -292,6 +292,10 @@ bool CaptureCore(
         }
 
         var captureContext = PostHogContextHelper.ResolveCaptureContext(distinctId, properties);
+        object? geoIpDisableOverride = null;
+        var hasGeoIpDisableOverride = captureContext.Properties?.TryGetValue(
+            PostHogProperties.GeoIpDisable,
+            out geoIpDisableOverride) == true;
 
         var capturedEvent = new CapturedEvent(
             eventName,
@@ -306,6 +310,11 @@ bool CaptureCore(
 
         capturedEvent.Properties.Merge(_options.Value.SuperProperties);
 
+        if (hasGeoIpDisableOverride)
+        {
+            capturedEvent.Properties[PostHogProperties.GeoIpDisable] = geoIpDisableOverride!;
+        }
+
         // Stamp $is_server last so a super property can't override the SDK's server/client classification.
         if (_options.Value.IsServer)
         {

tests/UnitTests/PostHogClientTests.cs

@@ -415,6 +415,37 @@ static JsonElement GetOnlyBatchItem(FakeHttpMessageHandler.RequestHandler batchH
 
 public class TheCaptureMethod
 {
+    [Theory]
+    [InlineData(true, false)]
+    [InlineData(false, true)]
+    public async Task CapturePropertiesOverrideConfiguredGeoIpDisable(bool superValue, bool perCaptureValue)
+    {
+        var container = new TestContainer(services => services.Configure<PostHogOptions>(options =>
+        {
+            options.SuperProperties["$geoip_disable"] = superValue;
+        }));
+        var requestHandler = container.FakeHttpMessageHandler.AddBatchResponse();
+        var client = container.Activate<PostHogClient>();
+
+        client.Capture(
+            "test-user",
+            "geoip-event",
+            new Dictionary<string, object>
+            {
+                ["$geoip_disable"] = perCaptureValue,
+                ["$ip"] = "203.0.113.42"
+            });
+        await client.FlushAsync();
+
+        using var document = JsonDocument.Parse(requestHandler.GetReceivedRequestBody(indented: false));
+        var properties = document.RootElement
+            .GetProperty("batch")[0]
+            .GetProperty("properties");
+
+        Assert.Equal(perCaptureValue, properties.GetProperty("$geoip_disable").GetBoolean());
+        Assert.Equal("203.0.113.42", properties.GetProperty("$ip").GetString());
+    }
+
     [Fact]
     public async Task SendsEnrichedCapturedEventsWhenSendFeatureFlagsTrueButDoesNotMakeSameDecideCallTwice()
     {