Push notifications silently broken since knip dead-code removal (PR #7022)

[diega]

Bug description

PR #7022 removed src/service-workers/index.ts and src/service-workers/firebase-messaging/firebase-messaging-sw.ts as dead code flagged by knip. However, these files were not part of the main app bundle's import graph — they were compiled separately by @ducanh2912/next-pwa via the customWorkerSrc option in next.config.mjs.

Without these files, public/firebase-messaging-sw.js remains empty (0 bytes) after build, so onBackgroundMessage is never registered and push notifications are silently dropped by the browser.

The remaining files in src/service-workers/firebase-messaging/ (notifications.ts, notification-mapper.ts, gateway-utils.ts, webhook-types.ts) are now effectively dead code since nothing imports them.

See: #7022 (comment)

Environment

• Browser: Any (Chrome, Firefox)
• Wallet: Any
• Chain: Any

Steps to reproduce

1. Build the app from main after PR #7022 was merged
2. Check public/firebase-messaging-sw.js — it's 0 bytes
3. Enable push notifications in the app
4. Send a notification while the app is in the background

Expected result

Background push notifications are received and displayed.

Obtained result

Notifications are silently dropped. No error in console — the service worker is registered but has no code to handle incoming messages.

Today's date: 2026-07-31

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🤖 Refined and Investigated by Claude — 2026-07-31

Session: Wallet Hygiene cloud routine, run 2026-07-31 (batch 4/6)

Labels added: Type → Bug, Tech → Frontend

Investigation notes:

• Code: confirmed apps/web/next.config.mjs still configures customWorkerSrc: SERVICE_WORKERS_PATH and swSrc: '${SERVICE_WORKERS_PATH}/index.ts' pointing at ./src/service-workers, consistent with the report that push notifications depend on files under that path existing at build time. Several live files (apps/web/src/services/push-notifications/tracking.ts, preferences.ts, useNotificationTracking.ts, PushNotifications/index.tsx) still import @/service-workers/firebase-messaging/webhook-types — so that specific file is NOT dead code, contrary to the ticket's claim that all four remaining files are unused. Also found docs/solutions/tanstack-pwa-sri-20260602.md, which explicitly cites "Background push silently broken (regression Push notifications silently broken since knip dead-code removal (PR #7022) #7568) since knip removed the FCM worker (PR #7022)" and describes merging FCM handling into one worker for the new apps/web-tanstack app — this corroborates the regression is real and already known internally, with the fix so far scoped to the new Vite/tanstack app rather than the original Next.js apps/web this ticket is about.
• Notion: not searched (code search already produced a strong, specific lead).
• Datadog/Mixpanel: not applicable — no relevant funnel/monitor identified for this regression.
• Unclear/missing: whether apps/web's original Next.js build has since been separately fixed, or whether the regression is still live in production for it — the internal doc only confirms the fix path for the new tanstack app.

Flagged for a human: (1) ticket has been in Triage status for ~120 days despite being a confirmed, reproducible regression with a named assignee (Daniel Dimitrov) — worth escalating out of Triage; (2) the ticket's claim that notifications.ts, notification-mapper.ts, gateway-utils.ts, and webhook-types.ts are all dead code is only partially accurate — webhook-types.ts is still actively imported — verify before treating the "cleanup remaining dead files" framing as accurate.

Auto-generated best-effort draft. Edit freely. React 👎 on this issue or ping to flag misses so I learn.