sequenceDiagram
    participant C as Client
    participant D as DTS
    participant A as Worker A
    participant B as Worker B
    Note over A,B: Matching handlers registered<br/>both workers connected
    C->>D: Start one execution
    D->>A: Graph step
    A-->>D: Step result + checkpoint bundle
    D->>A: Flight, hotel, car activities<br/>(may run in parallel)
    A-->>D: Flight + hotel results
    Note over D: Completions recorded<br/>in service history
    Note over A: Dies during car<br/>no completion recorded
    D->>B: Pending car + carried bundle
    B->>B: Hydrate graph state<br/>execute car
    B-->>D: Car result
    D->>B: Continue graph step + bundle
    B-->>D: New step result + bundle
    D-->>C: Original execution result