Implement SDK state persistence across page reloads via sessionStorage

[Kingsman-99]

Overview

The SDK loses all cached state on page reload, causing redundant RPC calls on navigation. Add opt-in sessionStorage persistence so cached data survives page refreshes within the same browser tab.

Acceptance Criteria

• StellarSplitSDK({ cache: { persist: 'session' } }) option enables sessionStorage persistence
• On init, SDK hydrates its in-memory cache from sessionStorage entries that are not yet expired
• On cache write, entry is also written to sessionStorage with expiry timestamp
• On cache evict/invalidate, entry is removed from sessionStorage
• Storage key prefix: split-sdk-cache: to avoid collisions
• Graceful degradation: if sessionStorage is unavailable (private browsing quota), falls back to memory-only silently
• sdk.clearPersistedCache() wipes all split-sdk-cache: keys from sessionStorage
• Does not persist in Node.js environments (sessionStorage unavailable — silently skipped)

[Turawa2]

@Turawa2 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I can work on the issue perfectly.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Turawa2 to this issue.

[estyemma]

@estyemma has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Please assign this issue to me

ℹ️ Repo Maintainers: To accept this application, review their application or assign @estyemma to this issue.

[Douglas4tech]

@Douglas4tech has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I’m interested in contributing to this issue and believe I can deliver a clean, well-tested solution that aligns with the project’s standards.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Douglas4tech to this issue.

[valoryyaa-byte]

@valoryyaa-byte has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

i would love to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @valoryyaa-byte to this issue.

[drips-wave]

Congratulations, @valoryyaa-byte! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @valoryyaa-byte: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊