Function build_execution_snapshot 

pub fn build_execution_snapshot(
    execution_id: ExecutionId,
    core: &HashMap<String, String>,
    tags_raw: HashMap<String, String>,
) -> Result<Option<ExecutionSnapshot>, EngineError>

Assemble an ExecutionSnapshot from the raw HGETALL field maps.

core is the HGETALL of exec_core, tags_raw the HGETALL of the sibling tags hash (which may be empty for executions created without tags). Every parse failure surfaces as [EngineError::Validation { kind: Corruption, .. }] — fields that FCALLs write atomically are strict-required, while fields that clear on transition (blocking_reason, current_attempt_id, etc.) are treated as absent when empty.