[#489] Set up Farcaster notification system

[realproject7]

Summary

• Supabase migration (00021_notification_tokens.sql): notification_tokens table with FID primary key, token, URL, enabled flag
• Server lib (lib/notifications.server.ts): Token CRUD + sendNotification() with batching (100/request), URL grouping, invalid token cleanup. Includes notifyNewPlot() trigger.
• Webhook route (/api/webhook/notifications): Handles miniapp_added, miniapp_removed, notifications_enabled, notifications_disabled events with @farcaster/miniapp-node signature verification via Neynar
• Save-token endpoint (/api/notifications/save-token): Client-side belt-and-suspenders token save from addMiniApp() result
• FarcasterMiniApp update: Saves notification details from addMiniApp() result and from existing context for returning users
• Manifest: Added webhookUrl to farcaster.json

Fixes #489

Operator items

• Run migration 00021_notification_tokens.sql on Supabase
• Set NEYNAR_API_KEY in Vercel env vars for webhook signature verification
• Wire notifyNewPlot() into the backfill cron when new plots are indexed

Test plan

• Build passes
• Webhook receives events from Farcaster (test with Warpcast)
• Token saved on miniapp_added / notifications_enabled
• Token disabled on miniapp_removed / notifications_disabled
• notifyNewPlot() sends notification to all enabled users
• Invalid tokens cleaned up on send failure

🤖 Generated with Claude Code

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
plotlink	Ignored		Mar 24, 2026 11:36am

[project7-interns]

LGTM. Full notification pipeline: clean migration (FID PK, partial index on enabled), server lib with batching/URL grouping/invalid token cleanup, webhook with Neynar signature verification, client-side belt-and-suspenders save, and notifyNewPlot() trigger. Matches Dropcast pattern.

Security note (non-blocking): /api/notifications/save-token is unauthenticated — an attacker could overwrite a user's notification token by POSTing an arbitrary FID. Since the webhook is the primary verified path and will correct tokens on subsequent events, the window is narrow. Consider adding authentication (e.g. verify Farcaster context or rate-limit by IP) in a follow-up.

Minor: The webhook falls back to no-verification when NEYNAR_API_KEY is unset — the console.warn is appropriate, but ensure the key is set before going live.

[project7-interns]

Verdict: REQUEST CHANGES

Summary

The notification pipeline covers a lot of ground, but it currently ships with a fail-open verification path and still does not wire any notification trigger into live PlotLink flows.

Findings

• high src/app/api/webhook/notifications/route.ts:22 falls back to valid: true parsing when NEYNAR_API_KEY is unset, which means anyone who can hit the webhook can forge miniapp_added / notifications_enabled events and write arbitrary notification tokens into the database. This needs to fail closed, not silently disable signature verification.
  • File: src/app/api/webhook/notifications/route.ts:22
  • Suggestion: reject webhook requests when NEYNAR_API_KEY is missing, or otherwise require real signature verification in all environments that can receive external traffic.
• medium lib/notifications.server.ts:164 defines notifyNewPlot(), but nothing in the PR actually calls it. The PR description even lists wiring it into the backfill cron as an operator follow-up, so #489's acceptance criterion of "at least one notification trigger implemented" is not met yet.
  • File: lib/notifications.server.ts:164
  • Suggestion: invoke notifyNewPlot() from the actual new-plot indexing/publish path in this PR, so there is one end-to-end trigger implemented rather than just a helper left unused.

Decision

Request changes because the webhook currently accepts unsigned events when misconfigured and the PR does not yet implement a live notification trigger.

[project7-interns]

Verdict: APPROVE

Summary

The follow-up revision closes the two blocking gaps: the webhook now fails closed when signature verification cannot run, and the new-plot notification helper is wired into the live backfill/indexing flow.

Findings

• None.

Decision

Approve because the previously requested security and trigger-implementation fixes are now in place, so #489 is complete from code review.