Method save_workflow_checkpoint

core/src/store/file_store.rs:499–547

(
        &self,
        workflow_id: &str,
        checkpoint: &WorkflowCheckpoint,
    )

    }

    async fn save_workflow_checkpoint(
        &self,
        workflow_id: &str,
        checkpoint: &WorkflowCheckpoint,
    ) -> Result<()> {
        let path = self.workflow_checkpoint_path(workflow_id);
        if let Some(parent) = path.parent() {
            fs::create_dir_all(parent).await.with_context(|| {
                format!(
                    "Failed to create workflow checkpoint directory: {}",
                    parent.display()
                )
            })?;
        }
        let json = serde_json::to_string_pretty(checkpoint).with_context(|| {
            format!("Failed to serialize workflow checkpoint for {workflow_id}")
        })?;

        // Crash-atomic write (temp + fsync + rename) — same rationale as
        // loop checkpoints: a truncated checkpoint would fail to resume.
        let unique_suffix = format!(
            "{}.{}",
            std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .map(|d| d.as_nanos())
                .unwrap_or(0),
            std::process::id()
        );
        let temp_path = path.with_extension(format!("json.{}.tmp", unique_suffix));
        let mut file = fs::File::create(&temp_path).await.with_context(|| {
            format!(
                "Failed to create workflow checkpoint temp file: {}",
                temp_path.display()
            )
        })?;
        file.write_all(json.as_bytes())
            .await
            .with_context(|| format!("Failed to write workflow checkpoint for {workflow_id}"))?;
        file.sync_all()
            .await
            .with_context(|| format!("Failed to fsync workflow checkpoint for {workflow_id}"))?;
        fs::rename(&temp_path, &path).await.with_context(|| {
            format!(
                "Failed to rename workflow checkpoint into place: {}",
                path.display()
            )
        })?;
        Ok(())
    }

    async fn load_workflow_checkpoint(
        &self,