0692 — Alert evaluations carry findings and evidence

Context

Moving partition-count observation and storage behind RecordMeasurement kept a different execution pattern from the other alert workers. The user rejected that alternate path and approved one Evaluate -> Record contract.

Decision

Superseded by 0693: measurements belong to metrics collection, not alert evaluation or recording.

• Continue 0689 through the existing Evaluator interface. Evaluate returns AlertEvaluation, containing the condition’s finding and measurements to retain.
• Every scheduled alert worker calls Evaluate and then Record. Evaluate owns source reads and comparison; Record owns evidence storage and the existing serialized alert transition. Remove RecordMeasurement, MeasurementEvaluator, and partition count’s separate Observe/EvaluateMeasurement methods.
• Registration-time warnings inspect the same evaluation without calling Record. Healthy results have no Alert; evaluation failures return errors.
• Partition count retains raw measurements. The other conditions use the same contract without adding evidence shapes before their adoption review. Storage time remains the evidence clock under [0690].

Consequences

The workers share one flow, with no measurement persistence details or alternate recording method. Evidence survives a subsequent alert-write failure. This change does not enable pending duration or change alert cadence; history-based classification remains unfinished work inside Record.