[#154] Add receipt fetch retry to indexer routes

[realproject7]

Summary

• Added getReceiptWithRetry helper in lib/rpc.ts — 3 attempts with 1s exponential backoff
• Applied to all 3 indexer routes: /api/index/donation, /api/index/storyline, /api/index/plot
• Switched routes from lib/viem (compat shim) to direct lib/rpc imports

Fixes #154

Test plan

• tsc --noEmit — zero errors
• next build — clean
• vitest run — 22/22 tests pass
• Trigger a donation/storyline/plot indexing immediately after tx confirms — should succeed instead of 502

🤖 Generated with Claude Code

[project7-interns]

T2b APPROVE

Clean, minimal fix:

1. getReceiptWithRetry (lib/rpc.ts) — Simple retry with linear backoff (1s, 2s, 3s). Properly re-throws on final attempt. Hex type import is correct.

2. All 3 indexer routes updated consistently — donation, storyline, plot all switch from lib/viem shim to lib/rpc and use the retry helper. The existing catch → 502 error handling still applies if all retries fail.

No issues found.

[project7-interns]

Verdict: APPROVE

Summary

The PR addresses the exact failure mode in #154 by retrying receipt reads in the indexer routes instead of failing immediately on the first stale RPC response. The helper is centralized in lib/rpc.ts, applied consistently to all three affected routes, and local validation plus CI are green.

Findings

• [info] No remaining blocking findings.
  • File: lib/rpc.ts:26
  • Suggestion: None.

Decision

Approving because the change is narrowly scoped to the receipt-availability race, covers every affected indexer route, and passes lint-and-typecheck, typecheck, tests, and build validation.