Feature/overflow protection and dashboard improvements

[Joycejay17]

Fix Overflow Protection and Dashboard Improvements

closes #236
closes #237
closes #238
closes #239

Summary

This PR addresses issues #236, #237, #238, and #239 by adding overflow protection to the smart contract, integrating SSE for real-time dashboard updates, and implementing the stream detail page with full functionality.

Changes

Issue #236: Overflow Protection in Smart Contract

Files Modified:

• contracts/stream_contract/src/lib.rs
• contracts/stream_contract/src/test.rs

Changes:

• Replaced unwrap_or(i128::MAX) with explicit overflow handling in calculate_claimable
• Used checked_mul for rate_per_second * elapsed_seconds multiplication
• Caps at deposited_amount when overflow would occur
• Used checked_sub for deposited - withdrawn calculation
• Added unit test test_claimable_max_i128_rate_overflow to verify overflow protection
• Documented overflow boundary in code comments

Impact: Prevents integer overflow in claimable amount calculations, ensuring no overflow for any valid input.

Issue #237: Stream Creation Form with Freighter Integration

Status: Already implemented in frontend/components/dashboard/dashboard-view.tsx

The stream creation form already has Freighter wallet integration through the handleCreateStream function which calls sorobanCreateStream from lib/soroban.ts. The integration includes:

• Validation of recipient (valid Stellar address), token, amount, and duration
• Building unsigned create_stream Soroban XDR transaction
• Prompting Freighter to sign via signTransaction
• Submitting signed XDR to backend POST /v1/streams
• Displaying transaction lifecycle states
• Showing success toast with stream ID and link
• Handling errors (wallet rejected, insufficient balance, invalid recipient)

Issue #238: Real-Time Stream Dashboard with SSE Integration

Files Modified:

• frontend/hooks/useStreamEvents.ts (new file)
• frontend/components/dashboard/dashboard-view.tsx

Changes:

• Created useStreamEvents React hook for SSE subscription
• Supports filtering by stream IDs and user public keys
• Auto-reconnect with exponential backoff
• Handles event types: created, topped_up, withdrawn, cancelled, completed
• Keeps last 100 events in memory
• Integrated SSE hook into dashboard-view
• Subscribes to events for connected wallet public key
• Refreshes dashboard data when SSE events arrive
• Provides real-time balance updates without page reload

Impact: Users can now see live updates to their streams without refreshing the page.

Issue #239: Stream Detail Page with Actions

Files Modified:

• frontend/app/streams/[id]/page.tsx

Changes:

• Converted from mock data to real API data fetching
• Added withdraw action with Freighter wallet integration
• Added top-up action with amount input
• Added cancel action with confirmation
• Displays full stream info: sender, recipient, token, rate, dates
• Shows live claimable balance counter
• Shows progress bar with withdrawn/total
• Added loading and error states
• All actions sign and submit real Soroban transactions via Freighter

Impact: Users can now view detailed stream information and perform actions (withdraw, top-up, cancel) directly from the stream detail page.

Testing

Contract Tests

• Added test_claimable_max_i128_rate_overflow to verify overflow protection
• All existing contract tests continue to pass

Frontend Testing

• SSE integration tested with mock events
• Stream detail page tested with loading states and error handling
• Freighter wallet integration uses existing tested functions from lib/soroban.ts

Breaking Changes

None. All changes are backward compatible.

Checklist

• Code follows project style guidelines
• Self-review completed
• Commented complex code sections
• Updated documentation (code comments)
• No new warnings generated
• Tests added/updated
• All tests passing
• Changes committed in batches
• Branch pushed to remote