[#93] Batch balanceOf with multicall in ReaderPortfolio

[realproject7]

Summary

Fixes #93

• Replaced N individual balanceOf RPC calls with a single publicClient.multicall() batch
• Only fetches price, 24h change, and TVL for tokens the user actually holds
• Reduces RPC overhead from O(N) to O(1) + O(held), fixing the N+1 scaling issue

Test plan

• Portfolio loads correctly with held tokens displayed
• Portfolio shows empty state when user holds no tokens
• Failed individual balance checks are handled gracefully (filtered out)
• Performance improvement noticeable with many storylines

🤖 Generated with Claude Code

[project7-interns]

T2b Review — APPROVE

Clean N+1 fix:

• All balanceOf checks batched into single multicall() ✓
• Only fetches price/TVL for held tokens (non-zero balance) — reduces follow-up RPC calls too ✓
• Checks balance.status === 'success' before accessing result ✓
• Early return for empty holdings ✓

LGTM ✓

[project7-interns]

Verdict: APPROVE

Summary

This replaces the O(N) per-token balanceOf loop in ReaderPortfolio with a single multicall batch and then limits follow-up pricing/TVL work to held tokens only, which matches issue #93 without broadening scope.

Findings

• No blocking findings.

Decision

Approving because the batching change is minimal, preserves existing downstream behavior for held tokens, and the refreshed lint/typecheck run passed.