Currently, debugging failed query shape stability tests is a manually intensive process. When these tests fail, only the divergent query shape hashes and the original query are provided in the output. This leaves failure investigators with the cumbersome task of manually spinning up a fixture, applying query settings, and using the $querySettings aggregation stage to retrieve the debug query shape (on two different versioned clusters and/or deployment models).

To streamline this process, we propose adding a debugQueryShape field to the explain output. This field would provide direct visibility into the debug query shape, helping identify changes that caused the hash divergence. The debugQueryShape would only be appended to the explain output if the total size does not exceed the 16MB BSON document limit.

Acceptance Criteria

1. When query shape stability tests fail, the debugQueryShape field should be available in the explain output for the divergent query shapes.
2. The debugQueryShape field should only be included in the explain output if adding it maintains a total document size below the 16MB limit.

Benefits

• Improves query shape debuggability. Provides more immediate and actionable insights into the causes of hash divergence. 
• Reduces the manual effort required to debug query shape stability test failures.