Fix campaign broadcast email chunking #3202

devkiran · 2025-12-08T10:02:22Z

Summary by CodeRabbit

Bug Fixes
- Campaign email broadcasts now use chunked batch processing with per-chunk tracking and improved error handling, increasing reliability and consistency for large recipient lists.
- Notification records are created per processed chunk to ensure accurate delivery records.
- Existing scheduling/delay behavior preserved while improving stability during high-volume broadcasts.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

vercel · 2025-12-08T10:02:27Z

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Project	Deployment	Preview	Updated (UTC)
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coderabbitai · 2025-12-08T10:02:38Z

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📥 Commits

Reviewing files that changed from the base of the PR and between b014847 and f7178dd.

📒 Files selected for processing (1)

apps/web/app/(ee)/api/cron/campaigns/broadcast/route.ts (2 hunks)

Walkthrough

The broadcast campaign route now splits partnerUsers into EMAIL_BATCH_SIZE chunks, sends each chunk with a unique per-chunk idempotency key, creates NotificationEmail records after each chunk's successful response, and preserves per-chunk error handling and batching delays.

Changes

Cohort / File(s)	Summary
Email batch chunking & idempotency `apps/web/app/(ee)/api/cron/campaigns/broadcast/route.ts`	Splits partnerUsers into chunks (EMAIL_BATCH_SIZE) and iterates per-chunk; generates per-chunk idempotency keys using `campaign.id`, `startingAfter

Sequence Diagram(s)

sequenceDiagram
    autonumber
    participant CronRoute as API Route
    participant ChunkSender as sendBatchEmail / Email Provider
    participant DB as Database (NotificationEmail)
    participant Enqueue as Batch Enqueue / Scheduler

    CronRoute->>CronRoute: split partnerUsers into chunks
    loop for each chunk i
        CronRoute->>ChunkSender: sendChunk(payload, idempotencyKey_i)
        alt success
            ChunkSender-->>CronRoute: success + data
            CronRoute->>DB: create NotificationEmail records for chunk i
            CronRoute->>Enqueue: schedule next overall batch (if applicable)
        else failure
            ChunkSender-->>CronRoute: error
            CronRoute->>CronRoute: log error, continue or halt per logic
        end
        CronRoute->>CronRoute: optional delay between chunks
    end

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Validate idempotency key format and uniqueness across retries
Confirm NotificationEmail creation now aligns with downstream read/query expectations
Check edge cases: empty partnerUsers, partial chunk failures, and enqueue transition for final batch

Possibly related PRs

Filter out invalid recipients from batch email sends #3113 — touches batch email sending behavior and recipient filtering; likely related to per-chunk send/send-via-resend changes.

Suggested reviewers

steven-tey

Poem

🐇 Hop by hop the batches run,

Chunks dispatched until the job is done,
Keys in paw keep repeats away,
Tiny notes recorded chunk-by-chunk today,
— a rabbit's cheer for cleaner play ✨

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: implementing email chunking for campaign broadcasts to handle large partner user lists in batches.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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Actionable comments posted: 1

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 23ae40e and b5d6cd5.

📒 Files selected for processing (1)

apps/web/app/(ee)/api/cron/campaigns/broadcast/route.ts (2 hunks)

🧰 Additional context used

🧠 Learnings (2)

📚 Learning: 2025-11-17T05:19:11.972Z

Learnt from: devkiran
Repo: dubinc/dub PR: 3113
File: apps/web/app/(ee)/api/cron/payouts/charge-succeeded/send-paypal-payouts.ts:65-75
Timestamp: 2025-11-17T05:19:11.972Z
Learning: In the Dub codebase, `sendBatchEmail` (implemented in packages/email/src/send-via-resend.ts) handles filtering of emails with invalid `to` addresses internally. Call sites can safely use non-null assertions on email addresses because the email sending layer will filter out any entries with null/undefined `to` values before sending. This centralized validation pattern is intentional and removes the need for filtering at individual call sites.

Applied to files:

apps/web/app/(ee)/api/cron/campaigns/broadcast/route.ts

📚 Learning: 2025-11-12T22:23:10.414Z

Learnt from: TWilson023
Repo: dubinc/dub PR: 3098
File: apps/web/lib/actions/partners/message-program.ts:49-58
Timestamp: 2025-11-12T22:23:10.414Z
Learning: In apps/web/lib/actions/partners/message-program.ts, when checking if a partner can continue messaging after messaging is disabled, the code intentionally requires `senderPartnerId: null` (program-initiated messages) to prevent partners from continuing to send junk messages. Only conversations started by the program should continue after messaging is disabled, as a spam prevention mechanism.

Applied to files:

apps/web/app/(ee)/api/cron/campaigns/broadcast/route.ts

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)

GitHub Check: build

🔇 Additional comments (1)

apps/web/app/(ee)/api/cron/campaigns/broadcast/route.ts (1)

12-12: Import additions align with downstream usage

APP_DOMAIN_WITH_NGROK, chunk, and log are all used below (QStash URL, partner user chunking, and logging), so this import change is consistent and safe.

apps/web/app/(ee)/api/cron/campaigns/broadcast/route.ts

Update route.ts

b5d6cd5

devkiran requested a review from steven-tey December 8, 2025 10:02

vercel bot deployed to Preview December 8, 2025 10:07 View deployment

coderabbitai bot reviewed Dec 8, 2025

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apps/web/app/(ee)/api/cron/campaigns/broadcast/route.ts Show resolved Hide resolved

devkiran added 2 commits December 8, 2025 15:54

Update route.ts

b014847

Update route.ts

f7178dd

vercel bot deployed to Preview December 8, 2025 10:30 View deployment

vercel bot deployed to Preview December 8, 2025 10:37 View deployment

steven-tey approved these changes Dec 8, 2025

View reviewed changes

steven-tey merged commit b54ef3c into main Dec 8, 2025
7 of 8 checks passed

steven-tey deleted the campaign-broadcast-fix branch December 8, 2025 17:56

coderabbitai bot mentioned this pull request Dec 9, 2025

Refactor partner program summary cron job handling #3207

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Fix campaign broadcast email chunking #3202

Fix campaign broadcast email chunking #3202

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devkiran commented Dec 8, 2025 •

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Fix campaign broadcast email chunking #3202

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Walkthrough

Changes

Sequence Diagram(s)

Estimated code review effort

Possibly related PRs

Suggested reviewers

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devkiran commented Dec 8, 2025 •

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