sequenceDiagram
    autonumber
    participant D as Draft
    participant P as Probe Engine
    participant C as Markdown Cleaner
    participant O as Output Draft

    D->>P: Extract all URLs
    P->>P: Resolve DNS and check scheme
    P->>P: Probe HTTP Range bytes 0-0
    alt Status 2xx/3xx
        P-->>C: Mark live
    else Status 4xx/5xx or Timeout
        P-->>C: Mark dead
    end
    alt Target Money Link
        C->>O: Shield and retain link
    else Dead Filler Link
        C->>O: Unwrap anchor to plain text
    else Live Filler Link
        C->>O: Retain markdown link
    end