Email digest unsubscribe links fall back to localhost:3000 when API_URL is unset

[nanaf6203-bit]

Email digest unsubscribe links fall back to localhost:3000 when API_URL is unset

Labels / Complexity: bug · Trivial — Trivial

Summary

EmailDigestService.sendDigestForUser (src/email-digest/email-digest.service.ts) builds each digest's unsubscribe URL from this.configService.get<string>('API_URL', 'http://localhost:3000/api'). In any environment where API_URL is not configured, every digest email carries an unsubscribe link pointing at localhost:3000 — a dead link for recipients and a broken unsubscribe flow. This is a second instance of the defect class already fixed for the main email path (#1054, email.service.ts), here in the digest's own URL builder.

Proposal

• Remove the localhost fallback: fail configuration (or log loudly) when API_URL is unset, matching the fix pattern from Email unsubscribe links fall back to localhost:3000 when FRONTEND_URL is unset #1054.
• Add a test asserting the digest unsubscribe URL is built from a configured host.

Acceptance criteria

• Digest unsubscribe links never contain localhost unless explicitly configured for local development.
• The unsubscribe link in a sent digest reaches a working endpoint.

Getting started

• src/email-digest/email-digest.service.ts — the API_URL fallback line
• src/email/email.service.ts — the same defect already fixed in Email unsubscribe links fall back to localhost:3000 when FRONTEND_URL is unset #1054

Commands: npm test.

Good first files to read: src/email-digest/email-digest.service.ts, src/email/email.service.ts.

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