diff --git a/.gitmodules b/.gitmodules
index 06c9e18..93de146 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,4 +1,4 @@
 [submodule "tests/engine/engine-tests/engine-test-data"]
 	path = tests/engine/engine-tests/engine-test-data
 	url = git@github.com:Flagsmith/engine-test-data.git
-	branch = v3.0.0
+	branch = v3.1.0
diff --git a/flagsmith-engine/evaluation/evaluationContext/mappers.ts b/flagsmith-engine/evaluation/evaluationContext/mappers.ts
index 1fa898f..b0bfde0 100644
--- a/flagsmith-engine/evaluation/evaluationContext/mappers.ts
+++ b/flagsmith-engine/evaluation/evaluationContext/mappers.ts
@@ -5,7 +5,10 @@ import {
     GenericEvaluationContext,
     EnvironmentContext,
     IdentityContext,
-    SegmentSource
+    SegmentSource,
+    CustomFeatureMetadata,
+    SegmentsWithMetadata,
+    CustomSegmentMetadata
 } from '../models.js';
 import { EnvironmentModel } from '../../environments/models.js';
 import { IdentityModel } from '../../identities/models.js';
@@ -17,9 +20,13 @@ import { uuidToBigInt } from '../../features/util.js';
 export function getEvaluationContext(
     environment: EnvironmentModel,
     identity?: IdentityModel,
-    overrideTraits?: TraitModel[]
+    overrideTraits?: TraitModel[],
+    isEnvironmentEvaluation: boolean = false
 ): GenericEvaluationContext {
     const environmentContext = mapEnvironmentModelToEvaluationContext(environment);
+    if (isEnvironmentEvaluation) {
+        return environmentContext;
+    }
     const identityContext = identity
         ? mapIdentityModelToIdentityContext(identity, overrideTraits)
         : undefined;
@@ -40,7 +47,7 @@ function mapEnvironmentModelToEvaluationContext(
         name: environment.project.name
     };
 
-    const features: FeaturesWithMetadata = {};
+    const features: FeaturesWithMetadata<CustomFeatureMetadata> = {};
     for (const fs of environment.featureStates) {
         const variants =
             fs.multivariateFeatureStateValues?.length > 0
@@ -59,12 +66,12 @@ function mapEnvironmentModelToEvaluationContext(
             variants,
             priority: fs.featureSegment?.priority,
             metadata: {
-                flagsmithId: fs.feature.id
+                id: fs.feature.id
             }
         };
     }
 
-    const segmentOverrides: Segments = {};
+    const segmentOverrides: SegmentsWithMetadata<CustomSegmentMetadata> = {};
     for (const segment of environment.project.segments) {
         segmentOverrides[segment.id.toString()] = {
             key: segment.id.toString(),
@@ -79,18 +86,18 @@ function mapEnvironmentModelToEvaluationContext(
                           value: fs.getValue(),
                           priority: fs.featureSegment?.priority,
                           metadata: {
-                              flagsmithId: fs.feature.id
+                              id: fs.feature.id
                           }
                       }))
                     : [],
             metadata: {
                 source: SegmentSource.API,
-                flagsmithId: segment.id
+                id: segment.id
             }
         };
     }
 
-    let identityOverrideSegments: Segments = {};
+    let identityOverrideSegments: SegmentsWithMetadata<CustomSegmentMetadata> = {};
     if (environment.identityOverrides && environment.identityOverrides.length > 0) {
         identityOverrideSegments = mapIdentityOverridesToSegments(environment.identityOverrides);
     }
@@ -116,11 +123,16 @@ function mapIdentityModelToIdentityContext(
         traitsContext[trait.traitKey] = trait.traitValue;
     }
 
-    return {
+    const identityContext: IdentityContext = {
         identifier: identity.identifier,
-        key: identity.djangoID?.toString() || identity.compositeKey,
         traits: traitsContext
     };
+
+    if (identity.djangoID !== undefined) {
+        identityContext.key = identity.djangoID.toString();
+    }
+
+    return identityContext;
 }
 
 function mapSegmentRuleModelToRule(rule: any): any {
@@ -135,8 +147,10 @@ function mapSegmentRuleModelToRule(rule: any): any {
     };
 }
 
-function mapIdentityOverridesToSegments(identityOverrides: IdentityModel[]): Segments {
-    const segments: Segments = {};
+function mapIdentityOverridesToSegments(
+    identityOverrides: IdentityModel[]
+): SegmentsWithMetadata<CustomSegmentMetadata> {
+    const segments: SegmentsWithMetadata<CustomSegmentMetadata> = {};
     const featuresToIdentifiers = new Map<string, { identifiers: string[]; overrides: any[] }>();
 
     for (const identity of identityOverrides) {
@@ -153,7 +167,7 @@ function mapIdentityOverridesToSegments(identityOverrides: IdentityModel[]): Seg
             value: fs.getValue(),
             priority: -Infinity,
             metadata: {
-                flagsmithId: fs.feature.id
+                id: fs.feature.id
             }
         }));
 
diff --git a/flagsmith-engine/evaluation/models.ts b/flagsmith-engine/evaluation/models.ts
index 9b8cc06..c6d0c17 100644
--- a/flagsmith-engine/evaluation/models.ts
+++ b/flagsmith-engine/evaluation/models.ts
@@ -25,7 +25,7 @@ export enum SegmentSource {
 
 // Feature types
 export interface CustomFeatureMetadata extends FeatureMetadata {
-    flagsmithId: number;
+    id: number;
 }
 
 export interface FeatureContextWithMetadata<T extends FeatureMetadata = FeatureMetadata>
@@ -49,7 +49,7 @@ export type EvaluationResultFlags<T extends FeatureMetadata = FeatureMetadata> =
 
 // Segment types
 export interface CustomSegmentMetadata extends SegmentMetadata {
-    flagsmithId: number;
+    id?: number;
     source?: SegmentSource;
 }
 
@@ -68,7 +68,7 @@ export interface SegmentResultWithMetadata {
     metadata: CustomSegmentMetadata;
 }
 
-export type EvaluationResultSegments = EvaluationContextResult['segments'];
+export type EvaluationResultSegments = SegmentResultWithMetadata[];
 
 // Evaluation context types
 export interface GenericEvaluationContext<
diff --git a/flagsmith-engine/index.ts b/flagsmith-engine/index.ts
index 58f9adc..c57abd0 100644
--- a/flagsmith-engine/index.ts
+++ b/flagsmith-engine/index.ts
@@ -6,7 +6,7 @@ import {
     CustomFeatureMetadata,
     FlagResultWithMetadata
 } from './evaluation/models.js';
-import { getIdentitySegments } from './segments/evaluators.js';
+import { getIdentitySegments, getIdentityKey } from './segments/evaluators.js';
 import { EvaluationResultFlags } from './evaluation/models.js';
 import { TARGETING_REASONS } from './features/types.js';
 import { getHashedPercentageForObjIds } from './utils/hashing/index.js';
@@ -131,7 +131,7 @@ export function evaluateFeatures(
 
         const { value: evaluatedValue, reason: evaluatedReason } = hasOverride
             ? { value: finalFeature.value, reason: undefined }
-            : evaluateFeatureValue(finalFeature, context.identity?.key);
+            : evaluateFeatureValue(finalFeature, getIdentityKey(context));
 
         flags[finalFeature.name] = {
             name: finalFeature.name,
diff --git a/flagsmith-engine/segments/evaluators.ts b/flagsmith-engine/segments/evaluators.ts
index 0b08526..aecae7f 100644
--- a/flagsmith-engine/segments/evaluators.ts
+++ b/flagsmith-engine/segments/evaluators.ts
@@ -49,7 +49,7 @@ export function traitsMatchSegmentCondition(
 ): boolean {
     if (condition.operator === PERCENTAGE_SPLIT) {
         const contextValueKey =
-            getContextValue(condition.property, context) || context?.identity?.key;
+            getContextValue(condition.property, context) || getIdentityKey(context);
         const hashedPercentage = getHashedPercentageForObjIds([segmentKey, contextValueKey]);
         return hashedPercentage <= parseFloat(String(condition.value));
     }
@@ -173,3 +173,9 @@ export function getContextValue(jsonPath: string, context?: GenericEvaluationCon
         return undefined;
     }
 }
+
+export function getIdentityKey(context?: GenericEvaluationContext): string | undefined {
+    if (!context?.identity) return undefined;
+
+    return context.identity.key || `${context.environment.key}_${context.identity.identifier}`;
+}
diff --git a/flagsmith-engine/segments/models.ts b/flagsmith-engine/segments/models.ts
index 8f3fb4b..a61c0c1 100644
--- a/flagsmith-engine/segments/models.ts
+++ b/flagsmith-engine/segments/models.ts
@@ -227,13 +227,13 @@ export class SegmentModel {
             if (segmentResult.metadata?.source === SegmentSource.IDENTITY_OVERRIDE) {
                 continue;
             }
-            const flagsmithId = segmentResult.metadata?.flagsmithId;
-            if (!flagsmithId) {
+            const segmentMetadataId = segmentResult.metadata?.id;
+            if (!segmentMetadataId) {
                 continue;
             }
-            const segmentContext = evaluationContext.segments[flagsmithId.toString()];
+            const segmentContext = evaluationContext.segments[segmentMetadataId.toString()];
             if (segmentContext) {
-                const segment = new SegmentModel(flagsmithId, segmentContext.name);
+                const segment = new SegmentModel(segmentMetadataId, segmentContext.name);
                 segment.rules = segmentContext.rules.map(rule => new SegmentRuleModel(rule.type));
                 segment.featureStates = SegmentModel.createFeatureStatesFromOverrides(
                     segmentContext.overrides || []
@@ -249,13 +249,13 @@ export class SegmentModel {
         if (!overrides) return [];
         return overrides
             .filter(override => {
-                const flagsmithId = override?.metadata?.flagsmithId;
-                return typeof flagsmithId === 'number';
+                const overrideMetadataId = override?.metadata?.id;
+                return typeof overrideMetadataId === 'number';
             })
             .map(override => {
-                const flagsmithId = override.metadata!.flagsmithId as number;
+                const overrideMetadataId = override.metadata!.id as number;
                 const feature = new FeatureModel(
-                    flagsmithId,
+                    overrideMetadataId,
                     override.name,
                     override.variants?.length && override.variants.length > 0
                         ? CONSTANTS.MULTIVARIATE
diff --git a/sdk/index.ts b/sdk/index.ts
index 81cbde7..6618ed8 100644
--- a/sdk/index.ts
+++ b/sdk/index.ts
@@ -25,6 +25,7 @@ import {
 } from './types.js';
 import { pino, Logger } from 'pino';
 import { getEvaluationContext } from '../flagsmith-engine/evaluation/evaluationContext/mappers.js';
+import { EvaluationContextWithMetadata } from '../flagsmith-engine/evaluation/models.js';
 
 export { AnalyticsProcessor, AnalyticsProcessorOptions } from './analytics.js';
 export { FlagsmithAPIError, FlagsmithClientError } from './errors.js';
@@ -282,7 +283,7 @@ export class Flagsmith {
         if (!context) {
             throw new FlagsmithClientError('Local evaluation required to obtain identity segments');
         }
-        const evaluationResult = getEvaluationResult(context);
+        const evaluationResult = getEvaluationResult(context as EvaluationContextWithMetadata);
 
         return SegmentModel.fromSegmentResult(evaluationResult.segments, context);
     }
@@ -449,11 +450,11 @@ export class Flagsmith {
 
     private async getEnvironmentFlagsFromDocument(): Promise<Flags> {
         const environment = await this.getEnvironment();
-        const context = getEvaluationContext(environment);
+        const context = getEvaluationContext(environment, undefined, undefined, true);
         if (!context) {
             throw new FlagsmithClientError('Unable to get flags. No environment present.');
         }
-        const evaluationResult = getEvaluationResult(context);
+        const evaluationResult = getEvaluationResult(context as EvaluationContextWithMetadata);
         const flags = Flags.fromEvaluationResult(evaluationResult);
 
         if (!!this.cache) {
@@ -481,7 +482,7 @@ export class Flagsmith {
         if (!context) {
             throw new FlagsmithClientError('Unable to get flags. No environment present.');
         }
-        const evaluationResult = getEvaluationResult(context);
+        const evaluationResult = getEvaluationResult(context as EvaluationContextWithMetadata);
 
         const flags = Flags.fromEvaluationResult(
             evaluationResult,
diff --git a/sdk/models.ts b/sdk/models.ts
index 17b0b22..ebea0d2 100644
--- a/sdk/models.ts
+++ b/sdk/models.ts
@@ -118,10 +118,10 @@ export class Flags {
     ): Flags {
         const flags: { [key: string]: Flag } = {};
         for (const flag of Object.values(evaluationResult.flags)) {
-            const flagsmithId = flag.metadata?.flagsmithId;
-            if (!flagsmithId) {
+            const flagMetadataId = flag.metadata?.id;
+            if (!flagMetadataId) {
                 throw new Error(
-                    `FlagResult metadata.flagsmithId is missing for feature "${flag.name}". ` +
+                    `FlagResult metadata.id is missing for feature "${flag.name}". ` +
                         `This indicates a bug in the SDK, please report it.`
                 );
             }
@@ -129,7 +129,7 @@ export class Flags {
             flags[flag.name] = new Flag({
                 enabled: flag.enabled,
                 value: flag.value ?? null,
-                featureId: flagsmithId,
+                featureId: flagMetadataId,
                 featureName: flag.name,
                 reason: flag.reason
             });
diff --git a/tests/engine/engine-tests/engine-test-data b/tests/engine/engine-tests/engine-test-data
index 8d19e96..6ab57ec 160000
--- a/tests/engine/engine-tests/engine-test-data
+++ b/tests/engine/engine-tests/engine-test-data
@@ -1 +1 @@
-Subproject commit 8d19e9627013c0e0213c29f3318fd45a179868fa
+Subproject commit 6ab57ec67bc84659e8b5aa41534b04fe45cc4cbe
diff --git a/tests/engine/unit/engine.test.ts b/tests/engine/unit/engine.test.ts
index c1a60a3..1c43f8e 100644
--- a/tests/engine/unit/engine.test.ts
+++ b/tests/engine/unit/engine.test.ts
@@ -115,7 +115,7 @@ test('shouldApplyOverride with priority conflicts', () => {
                 enabled: true,
                 value: 'value',
                 priority: 5,
-                metadata: { flagsmithId: 1 }
+                metadata: { id: 1 }
             },
             segmentName: 'segment1'
         }
@@ -185,7 +185,7 @@ test('evaluateSegments handles segments with identity identifier matching', () =
                 name: 'feature1',
                 enabled: false,
                 value: 'default_value',
-                metadata: { flagsmithId: 1 }
+                metadata: { id: 1 }
             }
         }
     };
@@ -272,7 +272,7 @@ test('evaluateSegments handles priority conflicts correctly', () => {
                 name: 'feature1',
                 enabled: false,
                 value: 'default_value',
-                metadata: { flagsmithId: 1 }
+                metadata: { id: 1 }
             }
         }
     };
@@ -343,7 +343,7 @@ test('evaluateFeatures with multivariate evaluation', () => {
                     { value: 'variant_a', weight: 0, priority: 1 },
                     { value: 'variant_b', weight: 100, priority: 2 }
                 ],
-                metadata: { flagsmithId: 1 }
+                metadata: { id: 1 }
             }
         },
         identity: { key: 'test_user', identifier: 'test_user' },
diff --git a/tests/engine/unit/segments/segments_model.test.ts b/tests/engine/unit/segments/segments_model.test.ts
index 0c84448..1210998 100644
--- a/tests/engine/unit/segments/segments_model.test.ts
+++ b/tests/engine/unit/segments/segments_model.test.ts
@@ -141,7 +141,7 @@ test('test_segment_rule_matching_function', () => {
 });
 
 test('test_fromSegmentResult_with_multiple_variants', () => {
-    const segmentResults = [{ name: 'test_segment', metadata: { flagsmithId: '1' } }];
+    const segmentResults = [{ name: 'test_segment', metadata: { id: '1' } }];
 
     const evaluationContext: EvaluationContext = {
         identity: {
@@ -159,7 +159,7 @@ test('test_fromSegmentResult_with_multiple_variants', () => {
                 name: 'test_segment',
                 metadata: {
                     source: SegmentSource.API,
-                    flagsmithId: '1'
+                    id: '1'
                 },
                 rules: [
                     {
@@ -181,7 +181,7 @@ test('test_fromSegmentResult_with_multiple_variants', () => {
                         value: 'default_value',
                         priority: 1,
                         metadata: {
-                            flagsmithId: 1
+                            id: 1
                         },
                         variants: [
                             { id: 1, value: 'variant_a', weight: 30 },
diff --git a/tests/sdk/flagsmith.test.ts b/tests/sdk/flagsmith.test.ts
index caa80f6..b0b66f3 100644
--- a/tests/sdk/flagsmith.test.ts
+++ b/tests/sdk/flagsmith.test.ts
@@ -520,7 +520,7 @@ test('get_user_agent_extracts_version_from_package_json', async () => {
     expect(userAgent).toBe(`flagsmith-nodejs-sdk/${packageJson.version}`);
 });
 
-test('Flags.fromEvaluationResult throws error when metadata.flagsmithId is missing', () => {
+test('Flags.fromEvaluationResult throws error when metadata.id is missing', () => {
     const evaluationResult = {
         flags: {
             test_feature: {
@@ -535,7 +535,7 @@ test('Flags.fromEvaluationResult throws error when metadata.flagsmithId is missi
     };
 
     expect(() => Flags.fromEvaluationResult(evaluationResult as any)).toThrow(
-        'FlagResult metadata.flagsmithId is missing for feature "test_feature". ' +
+        'FlagResult metadata.id is missing for feature "test_feature". ' +
             'This indicates a bug in the SDK, please report it.'
     );
 });