Problem

A concurrent delete between JOO sampling and CBR single-table planning can leave the sampling estimator at cardinality N while CBR uses N-1. Sampling CE then computes a selectivity greater than 1 and triggers tassert 9274202.

Reproduction

* Enable join optimization and disable the join plan cache.
* Create indexed collections with 100 documents.
* Pause at sleepWhileCbrPlanningForJoinOptimization.
* Delete one document from the base collection.
* Resume planning.

Observed failure:

Cardinality: 100, Source: Code must be < Cardinality: 99, Source: Metadata to produce selectivity

A deterministic reproducer is in jstests/noPassthrough/query/joins/cbr_joo_cardinality_race_repro.js.

Root Cause

JOO captures numRecords() when constructing the sampling estimator. CBR later captures numRecords() while constructing QueryPlannerParams, producing inconsistent cardinality snapshots.

Related Issues

* SERVER-128328 — sample cardinality authority can become stale.
* SERVER-123925 — JOO cardinality overestimation.
* SERVER-132009 — JOO debuggability improvements.