Overview

Validate that RecordStore, SortedDataInterface and container behavior is unchanged when backed by staged writes and the merged table cursor, and that transactions read their own writes through collection and index scans.

Scope of Work

• Run the existing RecordStore, SortedDataInterface and container test harnesses in staged mode.
• jstests for read-your-writes via collection scans, index scans, point lookups and updateWithDamages.
• Multi-update/multi-delete and $merge cases that read and write the same table in one statement (open question 3).
• Check the table-only read paths (random cursors, largest_key, statistics) for callers that rely on seeing their own uncommitted writes (open question 6).

Acceptance Criteria

• Harness and jstest results recorded on this ticket, with any failures triaged as bugs or documented prototype exclusions.
• Acceptance bar: the full jstest suite passes with featureFlagStagedWrites enabled, except for specific tests excluded with a documented reason tied to prototype scope.

Technical Notes

• Prototype quality; not intended for commit to master.
• Design reference: src/mongo/db/txns/staged_writes_design.md (PR #66680).