[#1239] Add Farcaster follow verification (verifyFc)

[realproject7]

Summary

• Creates lib/airdrop/activation-verify.ts with verifyFc(username, plotlinkFid)
• Two Neynar API calls: (1) GET /user/by_username → FID, (2) GET /user/bulk?viewer_fid → follow check
• Returns { ok: true, fid } on success, or { ok: false, error } with user_not_found / not_following / neynar_error
• No DB writes — caller endpoint handles persistence
• 9 unit tests: success, 404, 400, no-fid, not-following, 5xx on both calls, network failure, missing API key

Version

1.30.3 → 1.30.4

🤖 Generated with Claude Code

[vercel]

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
plotlink	Ignored		May 26, 2026 5:32am

[realproject7]

@re2 review — APPROVE ✅

Checked against issue #1239 acceptance criteria:

Criterion	Status
User-not-found → { ok: false, error: 'user_not_found' }	✅ (404, 400, missing fid)
Not-following → { ok: false, error: 'not_following' }	✅ (no partial DB write)
Following → { ok: true, fid }	✅
Neynar 5xx → neynar_error	✅ (both API calls)
No DB writes in this lib	✅ (no Supabase imports)
Version bump 1.30.3 → 1.30.4 (patch)	✅

Code review notes:

• Two-step Neynar flow correct: (1) username→FID lookup, (2) bulk user fetch with viewer_fid to check follow status via viewer_context.following.
• encodeURIComponent() on username prevents injection. API key passed via header.
• Both API calls wrapped in separate try/catch — network failures on either call gracefully return neynar_error.
• Missing API key returns error result (not throw) — consistent with R16 graceful degradation philosophy for this function.
• Discriminated union return type with specific error strings is clean for caller branching.
• 9 tests cover all paths including both 5xx scenarios, network failure, and missing key.

No issues found.

[project7-interns]

Verdict: APPROVE

Summary

The PR satisfies #1239: verifyFc performs the username lookup, checks the PlotLink follow relationship through Neynar viewer context, returns the required typed success/error results, and does not write to the database. Tests cover user-not-found, not-following, following, Neynar 5xx, network failure, missing API key, and no-FID response.

Findings

• No blocking findings.

Decision

Approve. lint-and-typecheck is passing; e2e was still pending at review time, so merge should still wait for required CI to complete successfully.