TZUTC: -0700
MSGID: 58500.sync_sys@1:103/705 2d05a49d
PID: Synchronet 3.21a-Linux master/27cbebcb9 Aug 10 2025 GCC 12.2.0
TID: SBBSecho 3.29-Linux master/27cbebcb9 Aug 10 2025 GCC 12.2.0
BBSID: VERT
CHRS: ASCII 1
FORMAT: flowed
https://gitlab.synchro.net/main/sbbs/-/issues/953#note_7536

The v3.20 code for detecting ANSI animation in a display file (and thus
resetting the line counter) was this:
```
/* ansi escape sequence */
if (outchar_esc >= ansiState_csi) {
    if (str[l] == 'A' || str[l] == 'B' || str[l] == 'H' || str[l] == 'J'
        || str[l] == 'f' || str[l] == 'u')    /* ANSI anim */
        lncntr = 0;         /* so defeat pause */
```

The new v3.21 code for this is now:

```
if ((!ansiParser.ansi_was_private) && ansiParser.ansi_ibs == "") {
    if (strchr("AFkBEeHfJdu", ansiParser.ansi_final_byte) != nullptr)    /*
ANSI anim */
    term->lncntr = 0; /* so defeat pause */
}
```
Which look sufficiently equivalent to me.

It makes sense that an ESC[255D would move the column counter (at least to the
right-most column <= 255, whatever that is). The last displayed line is
actually not blank (ends in "SysOp)"), but then there's a cursor reposition
with 'H' (triggering the reset logic above in both v3.20 and v3.21), followed
by an ESC[A which moves the cursor up one row, then the ESC[255D (moving to
the far right column), then CR LF LF.

So yeah, this is sufficiently convoluted that I do figure it just be an ANSI
animation file and thus all bets off with regards to line-counting and
auto-pausing. I don't know exactly what was happening in v3.20 (without
stepping through its code while displaying this file), but I'm kind of
surprised it considered there to be a non-zero line counter before the next
screen clear after displaying this file. Could've been unintended behavior in
v3.20 as I can imagine a sequence of animated-ANSI files that a sysop might
want to send without a [Hit a key] pause prompt appearing between them and the
v3.20 behavior couldn't been an unpleasant surprise. The reality is today,
most BBSes are used with speeds so fast that the user never actually sees the
ANSImation file unless they're artificially throttled.

So I'm fine to close the issue: SysOp shouldn't save the file as ANSImation
(e.g. in TheDraw) if they want Synchronet's auto-pause functionality.
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