Investigate AI-agent analysis report on the transactions specification. This ticket tracks findings identified during a systematic review of the spec: missing test coverage, ambiguous normative language, and spec/test inconsistencies.

Missing Tests

• On TransientTransactionError during non-commit/abort operation: session MUST be unpinned before SDAM retry — no
  test for this unpinning sequence (DRIVERS-3411 implementing:
  "Transaction state is preserved across retries")
• commitTransaction retry receives new recoveryToken: MUST track and use updated token in subsequent retries
• startTransaction with readPreference='secondary' MUST NOT be rejected — only read operations should be
  validated (spec: "MUST NOT validate during startTransaction")
• Unacknowledged write concern inherited from client/database defaults MUST be rejected in transactions
• Client error (invalid document structure) during "starting transaction" state MUST NOT change transaction state
• commitTransaction retry with existing wtimeout: w:majority MUST be applied but existing wtimeout MUST be
  preserved
• Transaction pinning/unpinning in Load Balancer mode (deferred to LB spec but no tests against LB topology)

Ambiguities

• NULL cascading for readConcern: "If NULL, inherit from defaultTransactionOptions. If also NULL, inherit from
  MongoClient." — unclear if "NULL" means "not set" or "explicitly set to null." Different interpretations lead to
  different behavior.
• startTransaction deployment detection (SHOULD): "SHOULD report an error if driver can detect transactions are
  not supported." SHOULD leaves inconsistent behavior across drivers.
• Error label for driver-generated timeouts: Spec adds TransientTransactionError to network errors during
  operations, but is a driver-generated timeout (not a server response) also labeled? Tests only verify
  server-generated labels.

Inconsistencies

• recoveryToken in sharded vs. replica set: Test files don't clearly separate RS-only vs. mongos-only recovery
  token scenarios. mongos-recovery-token.yml is mongos-specific but this isn't enforced by test runners.
• Automatic vs. explicit commitTransaction retry: Spec says behavior is identical for both, but they are not
  tested separately to confirm.

Notes

• 80 test files. Comprehensive coverage of state machines, error conditions, write concern, read preference, mongos
  pinning.
• do-not-retry-read-in-transaction test correctly prevents double-retry via retryable reads mechanism.
• PR #1804 /
  DRIVERS-1815 (implementing): clarify PoolClearedError labels,
  touches transactions spec.