Unit test red on main: 'Audit log: can handle separate subscriptions on separate dbs' (2 == 1, duplicate/leaked subscription event) #1141

Bug Summary

The resources unit test Audit log › can handle separate subscriptions on separate dbs (unitTests/resources/auditLog.test.js:502) fails on main:

AssertionError [ERR_ASSERTION]: 2 == 1
  at Context.<anonymous> (unitTests/resources/auditLog.test.js:502:11)

The test creates DB_COUNT = 3 tables on separate databases (test-subscribe0/1/2), subscribes to each, puts a single record into each, waits for the first data event per table, then asserts each subscription received exactly one event. One subscription receives 2 events for its single put — so this is either a duplicate data delivery or cross-database subscription event leakage.

Reproduction

• Node v22.21.1, RocksDB (default storage engine), macOS.
• Fails on a clean checkout of main (commit 266d5d8b), both:
  • in isolation: npx mocha unitTests/resources/auditLog.test.js — failed 5/5 runs (17 passing, 1 failing each).
  • in the full suite: npm run test:unit:resources — 685 passing … 2 failing on clean main (the other failure being Unit test red on main: 're-delivered duplicate must not double-apply the commutative op' (v22 + v26) #1137).

1. Check out main.
2. npm run build
3. npx mocha unitTests/resources/auditLog.test.js
4. Observe `can handle separate subscriptions on separate dbs` failing with `2 == 1`.

Notes / scope

• This is separate from Unit test red on main: 're-delivered duplicate must not double-apply the commutative op' (v22 + v26) #1137 (the commutative-op double-apply). Surfaced while triaging Unit test red on main: 're-delivered duplicate must not double-apply the commutative op' (v22 + v26) #1137: clean main actually has two red tests in the resources suite, not one. The Unit test red on main: 're-delivered duplicate must not double-apply the commutative op' (v22 + v26) #1137 CI run (https://github.com/HarperFast/harper/actions/runs/26961236701) reported only the Unit test red on main: 're-delivered duplicate must not double-apply the commutative op' (v22 + v26) #1137 failure with this test green — so this one appears environment/load-sensitive (deterministic on this machine, evidently passing on CI).
• The test was added in f4742911 (Test the separate db subscriptions) and most recently changed in ad7194db (replace the fixed delay(40) with an event-driven wait). The event-driven wait resolves on the first data event but then asserts the total count is 1 after Promise.all — so an extra/duplicate event on any one subscription trips it.

First triage question

Is one subscription receiving a duplicate data event for its own single put, or an event leaked from another database's table/log? The audit/transaction-log subscription machinery (RocksTransactionLogStore per-log iterators, listenToCommits) is the place to look — a subscription keyed to one db's log picking up another db's commit, or re-emitting a single commit twice, would both produce 2 == 1 here.

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