Added atomic newsletter email counters with drift comparison

[jonatansberg]

Newsletter analytics currently recount recipient history to refresh email statistics. The transactional flush in #30668 now tells us exactly which recipients changed, so we can maintain delivered, opened and failed counts in that same transaction. Replaying a delivery then leaves its count at one, even after a lost commit acknowledgement.

This is the email-only counter step. It lets us validate counters independently of the member preparation work in #30671 and its dependencies. Existing email counter columns are sufficient; there is no migration or historical email backfill.

flush one newsletter email
  begin transaction
    lock email row
    first touch after startup → recount existing facts, including opens
    lock eligible recipient rows in primary-key order
    write timestamps + increment counters from exact transitions
  commit
  remember that this worker established the baseline

aggregate
  lock email row → recount all three outcomes → report differences
  recount member statistics, including replayed members

The startup recount corrects existing counters once per touched email per worker lifetime. It normally covers active sends and the fetch trust window; scheduled recovery can also touch an older email. Baseline and increments share the email lock, so concurrent workers and retries can safely repeat initialization. Subsequent comparisons observe drift without repairing it. They always include opens, even when the fetch lane passes includeOpenedEvents: false.

The new emailAnalytics.emailCounterMode defaults to off. compare requires batchProcessing: true; mode changes require draining existing analytics workers and restarting with consistent configuration. Legacy writers do not take the counter lock. Member recomputation and its replay recovery remain in place. Automation/gift persistence and opens-first scheduling are unchanged.

Comparison logs signed differences and records comparison counts plus absolute observed drift by event type. See the email analytics README for startup, rollback and metric semantics. A restart rebaselines touched emails, so operators should inspect drift before restarting.

Validation:

• 108 MySQL email-service integration tests and 184 analytics unit tests passed.
• The final focused counter suite passed all 7 tests: existing opens at cutover, missing-lane comparison, deliberately wrong counters surviving comparison/replay, transaction rollback, lost commit acknowledgement plus restart, concurrent baselines, and comparison overlapping an uncommitted event transaction.
• Core/test TypeScript checks, focused lint and commit hooks passed. pnpm check stops on the same 452 pre-existing formatting files; none is changed here.
• Five independent slice reviews and five accumulated-stack review passes found no high-confidence issues.
• Synthetic benchmark: 5,000 members, 500 historical emails, 2,009,528 recipient rows, 5,000 events per cycle, 0/50/100% duplicate opens. All email/member truth assertions passed. Median handler reads increased 0.0023–0.0028% relative to Changed batched newsletter events to use exact transactional transitions #30668, including startup baselining. Comparison retains recount load; this does not claim the later read reduction. The harness uses innodb_flush_log_at_trx_commit=0 and no binlog, so absolute write timings are not production estimates.

Based on #30668; independent of the schema-only #30671. Removing mid-cycle email recounts follows after comparison has established correctness.

ref https://linear.app/ghost/issue/BER-3934
ref https://linear.app/ghost/issue/BER-3937

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☁️ Nx Cloud last updated this comment at 2026-09-11 14:50:21 UTC

[codecov]

Codecov Report

❌ Patch coverage is 87.38739% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.78%. Comparing base (b3e2c0d) to head (5ce34bd).

Files with missing lines	Patch %	Lines
...vices/email-analytics/newsletter-email-counters.ts	87.67%	1 Missing and 8 partials ⚠️
...core/core/server/services/email-analytics/index.ts	68.75%	1 Missing and 4 partials ⚠️

Additional details and impacted files

@@                               Coverage Diff                               @@
##           jonatan-ber-3933-transactional-email-events   #30674      +/-   ##
===============================================================================
+ Coverage                                        67.75%   67.78%   +0.02%     
===============================================================================
  Files                                             1670     1672       +2     
  Lines                                            60349    60448      +99     
  Branches                                         10436    10454      +18     
===============================================================================
+ Hits                                             40891    40975      +84     
- Misses                                           17151    17153       +2     
- Partials                                          2307     2320      +13     

Flag	Coverage Δ
e2e-tests	70.55% <87.38%> (+0.02%)	⬆️

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