sequenceDiagram
    autonumber
    participant Engine as Outreach Engine
    participant Guard as SSRF Guard
    participant Probe as safe_get()
    participant Server as Target Server

    Engine->>Probe: safe_get(url, Range="bytes=0-0")
    Probe->>Guard: Validate resolved IP
    Note over Guard: Check metadata, private, loopback ranges
    Guard-->>Probe: IP allowed (public)
    Probe->>Server: GET url (Range: bytes=0-0)
    Server-->>Probe: HTTP status (200/206/404/etc.)
    Note over Probe: Close connection without reading body
    Probe-->>Engine: Map status to verdict (live/dead/gone/error)