[FSSDK-12471] provider fix

[junaed-optimizely]

Summary

• Remove the cleanup effect that called store.reset() and UCM.dispose() on unmount
• Merge the onReady and CONFIG_UPDATE effects into a single effect with a configReceived flag

StrictMode compatibility (React 18+):

In dev mode, StrictMode runs effect cleanup→remount without re-running the render body. The cleanup effect called store.reset() (clearing userContext to null) and UCM.dispose() (aborting in-flight async operations like ODP segment fetches). Since the Provider doesn't re-render after effect remount, nobody restores the state — hooks stay stuck in isLoading: true forever. On real unmount, the store is garbage collected with the component tree, so eager reset is unnecessary.

Cached datafile race condition:

When the datafile response is served from the browser HTTP cache, the polling config manager loads it before the effect subscribes its CONFIG_UPDATE listener. Since the config doesn't change after subscription, the notification is never re-emitted, and hooks never transition from hasConfig: false to true. onReady().then() acts as a fallback for this case; the configReceived flag prevents a double-refresh when both fire on a cold cache.

Test plan

• Updated existing Provider specs to reflect new unmount behavior (store state preserved, not eagerly reset)
• Manually verified in a Next.js 15 + React 19 and React 17 app

Issues

FSSDK-12471

[Copilot]

Pull request overview

This PR updates OptimizelyProvider lifecycle behavior to be compatible with React 18+ StrictMode and to prevent a race where cached datafiles can cause hooks to remain stuck in a “loading / no-config” state.

Changes:

• Remove the unmount cleanup behavior that eagerly reset the provider store / disposed the user-context manager.
• Merge onReady() handling and OPTIMIZELY_CONFIG_UPDATE subscription into a single effect, with a configReceived flag to avoid double refreshes.
• Update provider unit tests to reflect the new unmount semantics.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/provider/OptimizelyProvider.tsx	Consolidates readiness + config-update handling and removes the unmount reset/dispose cleanup that breaks StrictMode remount behavior.
src/provider/OptimizelyProvider.spec.tsx	Updates cleanup-related expectations/descriptions to align with the new unmount behavior.

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