Notifications — FCM (transport) + Knock (orchestration)

Two-layer notifications: Knock + FCM' (in-app + email + SMS + web push); FCM stays as the web-push transport. Free 10K notifs/mo on Knock, free unlimited on FCM.

Notifications — FCM (transport) + Knock (orchestration)

Decision

Notifications are split across two layers:

• Orchestration — Knock. One workflow per event type (billing receipt, password change, comment reply, feature rollout). Knock owns channel selection, delivery order, dedupe windows, digest, per-user preferences, and the in-app feed. Free tier: 10,000 notifications/month.
• Transport — FCM for web push; Resend for email; Knock-bundled Twilio/MessageBird for SMS.

Knock’s web-push channel dispatches to FCM. Knock’s email channel dispatches to Resend. SMS is pay-per-message via Knock’s bundled providers (no monthly fee).

Why

• Building cross-channel orchestration on Workers is months of work. Knock gives us preference centers, digest windows, dedupe, branch-based environments (dev / staging / prod), and an in-app feed React component for free.
• FCM stays as transport because it’s free unlimited on Firebase Spark (locked forever by firebase-spark-forever), has first-class iOS PWA support, and tokens already live on Firebase Auth user records — letting Knock send web push directly would duplicate that storage and cost extra Knock notifications against the 10K cap.
• Resend stays as email transport for the same reason — it’s already wired for transactional email, free 3K/day, and Knock can point its email channel at Resend’s SMTP credentials.
• No card required at any layer. Spark + Resend + Knock all free-tier; per-site env-var toggle (same pattern as Sentry) keeps low-traffic sites from burning the 10K Knock cap.

Implications

Architecture

• One workflow per event type, defined in Knock’s dashboard. Workflows are exported as JSON and committed under packages/oriz-kit/notifications/workflows/ for replayable setup.
• @chirag127/oriz-kit ships a <KnockFeed /> component wrapping Knock’s React feed. Every site mounts it in the <AccountPanel> notifications drawer.
• Firebase Auth stores the per-user Knock recipient ID + FCM token on the user profile. The Hono Worker syncs Auth user changes to Knock recipients via webhook.
• Razorpay / Lemon Squeezy webhook ? Hookdeck ? Hono Worker ? Knock workflow trigger. Hookdeck stays in front for retry / replay.

Channel responsibility

Volume budget

• 10K notifications/month on Knock = ~330/day across the family.
• Per-site ENABLE_KNOCK=true|false env var keeps low-traffic sites silent until they need notifications.
• If we hit the cap: digest workflows (Knock supports daily / weekly digests natively) collapse multiple events into one notification, dropping volume by 5–10×.

What we don’t do

• No direct Knock web-push — every web-push goes through FCM.
• No self-hosted Novu — per .
• No Firebase Cloud Functions for notification fan-out — that would force Blaze (paid) to call third parties; Hono Worker on Cloudflare handles it free.
• No card-on-file at Knock or Twilio. SMS budget caps configured on the Twilio side via prepaid balance only.

Cross-refs

• Knock service entry
• FCM service entry
• push services index
• Resend — email transport behind Knock
• Firebase Spark forever
• Hookdeck — webhook reliability
• Never hit quotas rule
• No card-on-file rule

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