Prevent claim retries from duplicating intent

[Johnsource-hub]

closes #894

Summary:

• Add client-side intent deduplication to prevent duplicate transaction submissions when users retry claims.
• Persist minimal intent state in localStorage with a 24h TTL to allow retries to reuse signed XDR or detected submission hashes.
• Integrate intent handling into useTransaction to ensure deterministic behavior across retries and partial failures.

Files changed:

• lib/transaction/intent.ts - intent store (get/upsert/remove, computeXdrHash)
• hooks/useTransaction.hook.ts - integrate intent deduplication and locking
• lib/transaction/__tests__/intent.test.ts - intent store tests
• hooks/__tests__/useTransaction.test.tsx - focused transaction flow tests

Behavior and invariants:

• Intent key: walletAddress:sha256(builtXdr) ensures same wallet + same built XDR map to same intent.
• If an intent has submissionHash, retry polls for confirmation instead of re-submitting.
• If an intent has signedXdr but not submitted, retry will re-submit stored signedXdr (avoids re-signing in many cases).
• Signed XDRs are removed shortly after successful confirmation to reduce exposure.

Security considerations:

• Signed XDRs are persisted temporarily in localStorage. If this is unacceptable, switch to storing only the xdrHash and require re-signing on retry.
• Avoid storing private keys or secrets; only XDR strings are stored.

Testing:

• Unit tests cover intent store operations and transaction flows for sign-submit-confirm and retry scenarios.
• Run tests locally with pnpm test.

Migration / compatibility:

• No server changes or DB migrations required.
• Public API to useTransaction.executeTransaction(buildXdr) unchanged.

Observability:

• Intents are stored with timestamps and status; support can inspect localStorage under predictify:intents:v1 for debugging.

Next steps (optional):

• Consider encrypting signed XDR in localStorage or reducing persistence TTL.
• Add telemetry/metrics when intents transition to submitted and success.

[vercel]

@renoschubert is attempting to deploy a commit to the Jagadeesh B's projects Team on Vercel.

A member of the Team first needs to authorize it.

[drips-wave]

@Johnsource-hub Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits

[greatest0fallt1me]

Thanks for the implementation. Before this can be merged, please add a valid issue-closing reference in the PR description, such as Closes #894. The current #closes/#894 text is not recognized by GitHub as a linked issue.

[Johnsource-hub]

done