[FSSDK-11528] Holdout support in decision service

[junaed-optimizely]

Summary

Added holdout support in decision service and minor project config adjustments

Test plan

Tests have been added to support the new implementation

Issues

• FSSDK-11528

[coveralls]

coverage: 79.048%. first build
when pulling 56fd283 on junaed/fssdk-11528-add-holdout-support
into 51438cf on master.

[Copilot]

Pull Request Overview

This PR adds holdout support to the decision service, allowing users to be bucketed into holdout variations as part of the feature flag decision process. The implementation includes holdout evaluation logic, proper fallback mechanisms, and comprehensive test coverage.

• Added holdout evaluation logic in the decision service with proper audience and traffic allocation checking
• Enhanced project configuration to properly handle holdout variations in the variation ID map
• Updated type definitions to use more generic experiment core types for better holdout compatibility

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
lib/utils/enums/index.ts	Added HOLDOUT decision source constant
lib/shared_types.ts	Updated ActivateListenerPayload to use ExperimentCore type
lib/project_config/project_config.ts	Enhanced holdout parsing to include variations in variationIdMap
lib/notification_center/type.ts	Updated type definitions to use ExperimentCore
lib/core/decision_service/index.ts	Implemented holdout evaluation logic with proper fallback handling
lib/core/decision_service/index.spec.ts	Added comprehensive test coverage for holdout functionality
lib/core/bucketer/index.ts	Added null safety check for experiment lookup

Comments suppressed due to low confidence (2)

lib/core/decision_service/index.ts:81

• The import name 'holdout' is ambiguous as it conflicts with the Holdout type. Consider renaming to 'isHoldoutEnabled' or 'holdoutFeatureToggle' for clarity.

import { holdout } from '../../feature_toggle';

lib/core/decision_service/index.ts:944

• The function call 'holdout()' is ambiguous due to the naming conflict with the Holdout type. This should be renamed to match the import suggestion above.

    if (holdout()) {

[muzahidul-opti]

LGTM

[raju-opti]

Looks good. few small suggestions