Add Error Handling

Purpose

Implement comprehensive error handling for current code to make it robust and resilient while maintaining good UX.

Steps

1. Error Detection: Identify potential failure points, edge cases, unhandled exceptions, missing validation, async/network call issues
2. Error Handling Strategy: Implement try-catch blocks, add input validation/sanitization, create meaningful error messages/logging, design graceful degradation
3. Recovery Mechanisms: Retry only when the write is replay-safe (idempotency key or equivalent deduplication). Otherwise keep an explicit no-retry path. Permitted retries need a bounded deadline, cancellation, and backoff. Add fallbacks and circuit breakers only where they do not hide the owning failure
4. User Experience: Provide clear error messages, implement proper error status codes for APIs, add loading states/error boundaries for UI, include helpful suggestions

Follow the error-handling page listed from the technical docs path in AGENTS.md.

Completion

Read completion evidence before reporting completion.