feat(all): tag OpenFeature exposures with $openfeature_provider (SDK-448)

openfeature-provider/src/main/java/com/mixpanel/openfeature/MixpanelProvider.java

@@ -206,17 +206,19 @@ private <T> T coerce(Object value, Class<T> targetType) {
 
     static Map<String, Object> convertContext(EvaluationContext ctx) {
         Map<String, Object> context = new HashMap<>();
-        if (ctx == null) {
-            return context;
-        }
-        String targetingKey = ctx.getTargetingKey();
-        if (targetingKey != null && !targetingKey.isEmpty()) {
-            context.put("targetingKey", targetingKey);
-        }
-        for (String key : ctx.keySet()) {
-            Value val = ctx.getValue(key);
-            context.put(key, unwrapValue(val));
+        if (ctx != null) {
+            String targetingKey = ctx.getTargetingKey();
+            if (targetingKey != null && !targetingKey.isEmpty()) {
+                context.put("targetingKey", targetingKey);
+            }
+            for (String key : ctx.keySet()) {
+                Value val = ctx.getValue(key);
+                context.put(key, unwrapValue(val));
+            }
         }
+        // SDK-448: marks exposures fired through this provider. Set after the
+        // customer attributes so it can't be overridden; older SDKs ignore the key.
+        context.put("$openfeature_provider", true);
         return context;
     }
 

openfeature-provider/src/test/java/com/mixpanel/openfeature/MixpanelProviderTest.java

@@ -402,6 +402,46 @@ public void testExplicitTargetingKeyAttributeOverriddenByGetTargetingKey() {
         assertEquals("user-123", captured.get("distinct_id"));
     }
 
+    @SuppressWarnings("unchecked")
+    @Test
+    public void testContextIncludesOpenFeatureProviderMarker() {
+        SelectedVariant<Object> variant = new SelectedVariant<>("on", true, null, null, null);
+        ArgumentCaptor<Map<String, Object>> contextCaptor = ArgumentCaptor.forClass(Map.class);
+        when(mockFlagsProvider.getVariant(eq("flag"), any(SelectedVariant.class), contextCaptor.capture(), eq(true)))
+                .thenReturn(variant);
+
+        Map<String, Value> attrs = new HashMap<>();
+        attrs.put("distinct_id", new Value("user-123"));
+        provider.getBooleanEvaluation("flag", false, new ImmutableContext(attrs));
+
+        Map<String, Object> captured = contextCaptor.getValue();
+        assertEquals(Boolean.TRUE, captured.get("$openfeature_provider"));
+        assertEquals("user-123", captured.get("distinct_id"));
+    }
+
+    @SuppressWarnings("unchecked")
+    @Test
+    public void testOpenFeatureProviderMarkerCannotBeOverriddenByCustomerAttribute() {
+        SelectedVariant<Object> variant = new SelectedVariant<>("on", true, null, null, null);
+        ArgumentCaptor<Map<String, Object>> contextCaptor = ArgumentCaptor.forClass(Map.class);
+        when(mockFlagsProvider.getVariant(eq("flag"), any(SelectedVariant.class), contextCaptor.capture(), eq(true)))
+                .thenReturn(variant);
+
+        Map<String, Value> attrs = new HashMap<>();
+        attrs.put("distinct_id", new Value("user-123"));
+        attrs.put("$openfeature_provider", new Value(false));
+        provider.getBooleanEvaluation("flag", false, new ImmutableContext(attrs));
+
+        Map<String, Object> captured = contextCaptor.getValue();
+        assertEquals(Boolean.TRUE, captured.get("$openfeature_provider"));
+    }
+
+    @Test
+    public void testConvertContextIncludesMarkerForNullContext() {
+        Map<String, Object> context = MixpanelProvider.convertContext(null);
+        assertEquals(Boolean.TRUE, context.get("$openfeature_provider"));
+    }
+
     // PROVIDER_NOT_READY
 
     @Test

src/main/java/com/mixpanel/mixpanelapi/featureflags/provider/BaseFlagsProvider.java

@@ -242,6 +242,22 @@ protected void trackExposure(String distinctId, String flagKey, String variantKe
         }
     }
 
+    /**
+     * Context key set by the Mixpanel OpenFeature provider (SDK-448). When present and
+     * {@code true}, exposure events are tagged with {@code "$openfeature_provider": true}.
+     */
+    static final String OPENFEATURE_PROVIDER_KEY = "$openfeature_provider";
+
+    /**
+     * Adds {@code "$openfeature_provider": true} to the exposure properties when the
+     * evaluation context was built by the Mixpanel OpenFeature provider.
+     */
+    static void addOpenFeatureProviderProperty(Map<String, Object> context, JSONObject properties) {
+        if (context != null && Boolean.TRUE.equals(context.get(OPENFEATURE_PROVIDER_KEY))) {
+            properties.put(OPENFEATURE_PROVIDER_KEY, true);
+        }
+    }
+
     // #endregion
 
     /**

src/main/java/com/mixpanel/mixpanelapi/featureflags/provider/LocalFlagsProvider.java

@@ -728,6 +728,7 @@ private void trackLocalExposure(Map<String, Object> context, String flagKey, Str
 
         trackExposure(distinctIdObj.toString(), flagKey, variantKey, "local", properties -> {
             properties.put("Variant fetch latency (ms)", latencyMs);
+            addOpenFeatureProviderProperty(context, properties);
         }, experimentId, isExperimentActive, isQaTester);
     }
 

src/main/java/com/mixpanel/mixpanelapi/featureflags/provider/RemoteFlagsProvider.java

@@ -193,6 +193,7 @@ private void trackRemoteExposure(Map<String, Object> context, String flagKey, St
         trackExposure(distinctIdObj.toString(), flagKey, variantKey, "remote", properties -> {
             properties.put("Variant fetch start time", startTime);
             properties.put("Variant fetch complete time", completeTime);
+            addOpenFeatureProviderProperty(context, properties);
         }, experimentId, isExperimentActive, isQaTester);
     }
 

src/test/java/com/mixpanel/mixpanelapi/featureflags/provider/LocalFlagsProviderTest.java

@@ -944,6 +944,42 @@ public void testTrackExposureWhenVariantIsSelected() {
         assertTrue(event.properties.getLong("Variant fetch latency (ms)") >= 0);
     }
 
+    @Test
+    public void testExposureIncludesOpenFeatureProviderPropertyWhenContextMarkerSet() {
+        List<Variant> variants = Arrays.asList(new Variant("variant-a", "value-a", false, 1.0f));
+        List<Rollout> rollouts = Arrays.asList(new Rollout(1.0f));
+        String response = buildFlagsResponse(flagKey, distinctIdContextKey, variants, rollouts, null);
+
+        provider = createProviderWithResponse(response);
+
+        Map<String, Object> context = buildContext("user-123");
+        context.put("$openfeature_provider", true);
+        provider.startPollingForDefinitions();
+        provider.getVariantValue(flagKey, fallbackVariantValue, context);
+
+        assertEquals(1, eventSender.getEvents().size());
+        MockEventSender.ExposureEvent event = eventSender.getEvents().get(eventSender.getEvents().size() - 1);
+        assertEquals("variant-a", event.properties.getString("Variant name"));
+        assertTrue(event.properties.getBoolean("$openfeature_provider"));
+    }
+
+    @Test
+    public void testExposureOmitsOpenFeatureProviderPropertyWithoutContextMarker() {
+        List<Variant> variants = Arrays.asList(new Variant("variant-a", "value-a", false, 1.0f));
+        List<Rollout> rollouts = Arrays.asList(new Rollout(1.0f));
+        String response = buildFlagsResponse(flagKey, distinctIdContextKey, variants, rollouts, null);
+
+        provider = createProviderWithResponse(response);
+
+        Map<String, Object> context = buildContext("user-123");
+        provider.startPollingForDefinitions();
+        provider.getVariantValue(flagKey, fallbackVariantValue, context);
+
+        assertEquals(1, eventSender.getEvents().size());
+        MockEventSender.ExposureEvent event = eventSender.getEvents().get(eventSender.getEvents().size() - 1);
+        assertFalse(event.properties.has("$openfeature_provider"));
+    }
+
     @Test
     public void testDoNotTrackExposureWhenReturningFallback() {
         // Empty flags - will return fallback

src/test/java/com/mixpanel/mixpanelapi/featureflags/provider/RemoteFlagsProviderTest.java

@@ -244,6 +244,34 @@ public void testTrackExposureWhenVariantIsSelected() {
         assertNotNull(event.properties.getString("Variant fetch complete time"));
     }
 
+    @Test
+    public void testExposureIncludesOpenFeatureProviderPropertyWhenContextMarkerSet() {
+        String response = buildRemoteFlagsResponse("test-flag", "variant-a", "test-value");
+        provider = createProviderWithResponse(response);
+
+        Map<String, Object> context = buildContext("user-123");
+        context.put("$openfeature_provider", true);
+        provider.getVariantValue("test-flag", "fallback", context);
+
+        assertEquals(1, eventSender.getEvents().size());
+        MockEventSender.ExposureEvent event = eventSender.getEvents().get(eventSender.getEvents().size() - 1);
+        assertEquals("variant-a", event.properties.getString("Variant name"));
+        assertTrue(event.properties.getBoolean("$openfeature_provider"));
+    }
+
+    @Test
+    public void testExposureOmitsOpenFeatureProviderPropertyWithoutContextMarker() {
+        String response = buildRemoteFlagsResponse("test-flag", "variant-a", "test-value");
+        provider = createProviderWithResponse(response);
+
+        Map<String, Object> context = buildContext("user-123");
+        provider.getVariantValue("test-flag", "fallback", context);
+
+        assertEquals(1, eventSender.getEvents().size());
+        MockEventSender.ExposureEvent event = eventSender.getEvents().get(eventSender.getEvents().size() - 1);
+        assertFalse(event.properties.has("$openfeature_provider"));
+    }
+
     @Test
     public void testDoNotTrackExposureWhenReturningFallback() {
         // Create provider that will throw IOException