Offline Init Part 2 of 4: Add getBanditsConfiguration() to export bandit models as JSON

.github/workflows/lint-test-sdk.yml

@@ -6,7 +6,7 @@ env:
 
 on:
   pull_request:
-    branches: [ "*" ]
+    branches: [ "**" ]
   workflow_dispatch:
   workflow_call:
     inputs:

src/index.spec.ts

@@ -33,6 +33,7 @@ import {
 import * as util from './util/index';
 
 import {
+  getBanditsConfiguration,
   getFlagsConfiguration,
   getInstance,
   IAssignmentEvent,
@@ -834,4 +835,81 @@ describe('EppoClient E2E test', () => {
       });
     });
   });
+
+  describe('getBanditsConfiguration', () => {
+    it('returns null when no bandits are configured', async () => {
+      await init({
+        apiKey: 'dummy',
+        baseUrl: `http://127.0.0.1:${TEST_SERVER_PORT}`,
+        assignmentLogger: { logAssignment: jest.fn() },
+      });
+
+      // The default mock doesn't include bandits, so this should return null
+      const banditsConfig = getBanditsConfiguration();
+      expect(banditsConfig).toBeNull();
+    });
+
+    it('returns bandits configuration JSON matching bandit-models-v1.json structure', async () => {
+      await init({
+        apiKey: TEST_BANDIT_API_KEY,
+        baseUrl: `http://127.0.0.1:${TEST_SERVER_PORT}`,
+        assignmentLogger: { logAssignment: jest.fn() },
+        banditLogger: { logBanditAction: jest.fn() },
+      });
+
+      const banditsConfig = getBanditsConfiguration();
+      expect(banditsConfig).not.toBeNull();
+
+      const parsed = JSON.parse(banditsConfig ?? '');
+
+      // Verify exact number of bandits from bandit-models-v1.json
+      expect(Object.keys(parsed.bandits).length).toBe(3);
+      expect(Object.keys(parsed.bandits).sort()).toEqual([
+        'banner_bandit',
+        'car_bandit',
+        'cold_start_bandit',
+      ]);
+
+      // Verify banner_bandit structure in detail
+      const bannerBandit = parsed.bandits['banner_bandit'];
+      expect(bannerBandit.banditKey).toBe('banner_bandit');
+      expect(bannerBandit.modelName).toBe('falcon');
+      expect(bannerBandit.modelVersion).toBe('123');
+      expect(bannerBandit.updatedAt).toBe('2023-09-13T04:52:06.462Z');
+
+      // Verify modelData
+      expect(bannerBandit.modelData.gamma).toBe(1.0);
+      expect(bannerBandit.modelData.defaultActionScore).toBe(0.0);
+      expect(bannerBandit.modelData.actionProbabilityFloor).toBe(0.0);
+
+      // Verify coefficients - should have nike and adidas
+      expect(Object.keys(bannerBandit.modelData.coefficients).sort()).toEqual(['adidas', 'nike']);
+
+      // Verify nike coefficient structure
+      const nikeCoeff = bannerBandit.modelData.coefficients['nike'];
+      expect(nikeCoeff.actionKey).toBe('nike');
+      expect(nikeCoeff.intercept).toBe(1.0);
+      expect(nikeCoeff.actionNumericCoefficients.length).toBe(1);
+      expect(nikeCoeff.actionNumericCoefficients[0]).toEqual({
+        attributeKey: 'brand_affinity',
+        coefficient: 1.0,
+        missingValueCoefficient: -0.1,
+      });
+      expect(nikeCoeff.actionCategoricalCoefficients.length).toBe(2);
+      expect(nikeCoeff.subjectNumericCoefficients.length).toBe(1);
+      expect(nikeCoeff.subjectCategoricalCoefficients.length).toBe(1);
+
+      // Verify car_bandit has different settings
+      const carBandit = parsed.bandits['car_bandit'];
+      expect(carBandit.modelVersion).toBe('456');
+      expect(carBandit.modelData.defaultActionScore).toBe(5.0);
+      expect(carBandit.modelData.actionProbabilityFloor).toBe(0.2);
+      expect(Object.keys(carBandit.modelData.coefficients)).toEqual(['toyota']);
+
+      // Verify cold_start_bandit has empty coefficients
+      const coldStartBandit = parsed.bandits['cold_start_bandit'];
+      expect(coldStartBandit.modelVersion).toBe('cold start');
+      expect(Object.keys(coldStartBandit.modelData.coefficients).length).toBe(0);
+    });
+  });
 });

src/index.ts

@@ -253,6 +253,35 @@ function reconstructBanditReferences(): Record<
   return banditReferences;
 }
 
+/**
+ * Returns the current bandits configuration as a JSON string.
+ * This can be used together with getFlagsConfiguration() to bootstrap
+ * another SDK instance using offlineInit().
+ *
+ * @returns JSON string containing the bandits configuration, or null if not initialized or no bandits
+ * @public
+ */
+export function getBanditsConfiguration(): string | null {
+  if (!banditModelConfigurationStore) {
+    return null;
+  }
+
+  const bandits = banditModelConfigurationStore.entries();
+
+  // Return null if there are no bandits
+  if (Object.keys(bandits).length === 0) {
+    return null;
+  }
+
+  const configuration: {
+    bandits: Record<string, BanditParameters>;
+  } = {
+    bandits,
+  };
+
+  return JSON.stringify(configuration);
+}
+
 function newEventDispatcher(
   sdkKey: string,
   config: IClientConfig['eventTracking'] = {},