When tag /tag/ has detection /any/ on camera /any/ at timestamp /any/ {
    # Setting aside this tag space (48600 to 48713) for calibration.
    if {$tag >= 48600} { return }

    Claim -keep 100ms tag $tag has a program
    Claim -keep 100ms tag $tag is a tag
}

When -noncapturing the program save directory is /saveDir/ {
    When /type/ /obj/ has a program {
        puts stderr "Added $type $obj"
        On unmatch { puts "Removed $type $obj" }

        if {![catch {QueryOne! $obj has demo code /demoCode/} res]} {
            Claim $obj has program code $res(demoCode)
            return
        }

        if {[file exists "$saveDir/$obj.folk.temp"]} {
            set fd [open "$saveDir/$obj.folk.temp" r]
        } else {
            if {![file exists "$saveDir/$obj.folk"] &&
                ($::thisNode eq "folk-beads" || $::thisNode eq "folk-convivial" || $::thisNode eq "gadget-platinum" || $::thisNode eq "gadget-pink")} {
                # HACK: 'Page fault' to folk-hex, try getting page from
                # there. Ideally we would have some general (Avahi?)
                # way of finding the 'authoritative' node on the local
                # network, or broadcasting out, and getting pages from
                # there.
                exec curl --output "$saveDir/$obj.folk" \
                    "http://folk-hex.local:4273/printed-programs/$obj.folk" &
                exec curl --output "$saveDir/$obj.meta.folk" \
                    "http://folk-hex.local:4273/printed-programs/$obj.meta.folk" &
                # HACK: It won't be reloaded until you redetect the tag.
            }

            try {
                set fd [open "$saveDir/$obj.folk" r]
            } on error err {
                puts stderr "No code for $type $obj ($err):\n  [errorInfo $err [info stacktrace]]"
                return
            }
        }
        set code [read $fd]
        close $fd

        if {[file exists "$saveDir/$obj.folk.edited"]} {
            set fd [open "$saveDir/$obj.folk.edited" r]
            set editedCode [read $fd]
            close $fd

            set editedTime [file mtime "$saveDir/$obj.folk.edited"]
            Hold! -on builtin-programs/programs.folk -key new-code-for:$obj \
                Wish program $obj is replaced with \
                code $editedCode editedTime $editedTime
        }

        Claim $obj has program code $code

        When /someone/ wishes program $obj is replaced with /...opts/ {
            set editedTime [dict get $opts editedTime]
            Wish $obj is titled "(edited [clock format $editedTime -format "%a, %d %b %Y, %I:%M %p"])"
        }

       if {[file exists "$saveDir/$obj.meta.folk"]} {
           set mfd [open "$saveDir/$obj.meta.folk" r]
           set metacode [read $mfd]; close $mfd
           apply [list {this} $metacode] $obj
       }
    }
}