fix(billing): address CodeRabbit findings on PR #3688

- Move lib/distributedLock.js → lib/services/distributedLock.js
  (aligns with existing convention for service-level primitives)
- Move lib/tests/distributedLock.unit.tests.js → lib/services/tests/
- Update import paths in 3 billing crons + integration tests
- Flip logger.error arg order in dunningSweep + extrasExpiration finally
  (match file convention: (message, meta) not (meta, message))
- Same fix applied to weeklyReset (same pattern found, not flagged by CR)
- Update modules/billing/crons/README.md → reference '## 6 — Cron lock stuck'
  (exact match with RUNBOOKS section header)

Heartbeat/renewLock suggestion intentionally NOT added — see PR reply.

Author: PierreBrisorgueil

lib/distributedLock.js lib/services/distributedLock.jslib/distributedLock.js renamed to lib/services/distributedLock.js

@@ -4,7 +4,7 @@
 import { jest, describe, test, beforeEach, afterEach, expect } from '@jest/globals';
 
 /**
- * Unit tests for lib/distributedLock.js
+ * Unit tests for lib/services/distributedLock.js
  *
  * All Mongoose interactions are mocked — no real DB connection required.
  * Tests verify the acquire / release contract and contention handling.

lib/tests/distributedLock.unit.tests.js …ices/tests/distributedLock.unit.tests.jslib/tests/distributedLock.unit.tests.js renamed to lib/services/tests/distributedLock.unit.tests.js lib/tests/distributedLock.unit.tests.js renamed to lib/services/tests/distributedLock.unit.tests.js

@@ -121,7 +121,7 @@ All scripts check `config.billing.meterMode` at startup. Downstream projects mus
 
 ## Concurrency control
 
-All billing crons acquire a distributed lock (`lib/distributedLock.js`) before
+All billing crons acquire a distributed lock (`lib/services/distributedLock.js`) before
 mutating state. The lock auto-expires after TTL (5–15 min depending on cron)
 so that pod crashes don't permanently block scheduling.
 
@@ -135,5 +135,5 @@ Lock names and TTLs:
 
 If you see `lock held by another pod, skipping` in logs, that is expected when
 two pods race after a K8s `concurrencyPolicy` bypass (e.g. pod crash after
-jitter but before finalize). See the runbook entry `## Cron lock stuck` in
+jitter but before finalize). See the runbook entry `## 6 — Cron lock stuck` in
 `modules/billing/RUNBOOKS.md` for manual resolution.

modules/billing/crons/README.md

@@ -34,7 +34,7 @@ const [
   import('../../../lib/services/logger.js'),
   import('../lib/billing.cron-utils.js'),
   import('../lib/billing.constants.js'),
-  import('../../../lib/distributedLock.js'),
+  import('../../../lib/services/distributedLock.js'),
 ]);
 
 if (!config?.billing?.meterMode) {
@@ -116,10 +116,10 @@ try {
       try {
         await releaseLock({ name: LOCK_NAME, holder: lockHolder });
       } catch (releaseErr) {
-        logger.error(
-          { err: releaseErr, cron: LOCK_NAME },
-          '[cron.dunningSweep] failed to release lock — will auto-expire on TTL',
-        );
+        logger.error('[cron.dunningSweep] failed to release lock — will auto-expire on TTL', {
+          err: releaseErr,
+          cron: LOCK_NAME,
+        });
       }
     }
   }

modules/billing/crons/billing.dunningSweep.js

@@ -29,7 +29,7 @@ const [
   import('../../../lib/services/logger.js'),
   import('../lib/billing.cron-utils.js'),
   import('../lib/billing.constants.js'),
-  import('../../../lib/distributedLock.js'),
+  import('../../../lib/services/distributedLock.js'),
 ]);
 
 if (!config?.billing?.meterMode) {
@@ -86,10 +86,10 @@ try {
       try {
         await releaseLock({ name: LOCK_NAME, holder: lockHolder });
       } catch (releaseErr) {
-        logger.error(
-          { err: releaseErr, cron: LOCK_NAME },
-          '[cron.extrasExpiration] failed to release lock — will auto-expire on TTL',
-        );
+        logger.error('[cron.extrasExpiration] failed to release lock — will auto-expire on TTL', {
+          err: releaseErr,
+          cron: LOCK_NAME,
+        });
       }
     }
   }

modules/billing/crons/billing.extrasExpiration.js

@@ -28,7 +28,7 @@ const [
   import('../../../lib/services/logger.js'),
   import('../lib/billing.cron-utils.js'),
   import('../lib/billing.constants.js'),
-  import('../../../lib/distributedLock.js'),
+  import('../../../lib/services/distributedLock.js'),
 ]);
 
 if (!config?.billing?.meterMode) {
@@ -66,10 +66,10 @@ try {
       try {
         await releaseLock({ name: LOCK_NAME, holder: lockHolder });
       } catch (releaseErr) {
-        logger.error(
-          { err: releaseErr, cron: LOCK_NAME },
-          '[cron.weeklyReset] failed to release lock — will auto-expire on TTL',
-        );
+        logger.error('[cron.weeklyReset] failed to release lock — will auto-expire on TTL', {
+          err: releaseErr,
+          cron: LOCK_NAME,
+        });
       }
     }
   }

modules/billing/crons/billing.weeklyReset.js

@@ -4,10 +4,10 @@
 import { describe, beforeAll, beforeEach, afterAll, test, expect } from '@jest/globals';
 
 import mongooseService from '../../../lib/services/mongoose.js';
-import { acquireLock, releaseLock, CronLock } from '../../../lib/distributedLock.js';
+import { acquireLock, releaseLock, CronLock } from '../../../lib/services/distributedLock.js';
 
 /**
- * Integration tests for lib/distributedLock.js — real MongoDB.
+ * Integration tests for lib/services/distributedLock.js — real MongoDB.
  *
  * Verifies the acquire / release / contention / expiry contract end-to-end.
  * The cron scripts themselves are top-level-await CLI entry points that cannot