Play waits for its own sound to finish before handing back

The gates all go down on the tick the tracks end, but a gate down is a
note RELEASED and not a note stopped: the oboe and the strings have a
release left to run. Rendered and measured, the tail dies eight tenths of
a second after the last event, and the ring was eight ticks - one second,
which sounds like enough and was two tenths short.

A program that exits with sound still in the air leaves nothing able to
end it: the program is gone and cannot drop a gate. What that becomes
depends on the front end. Behind a window the tail finishes on its own.
On a terminal it does not, because emulated time stops while the machine
blocks on a key - measured, and the reason the leftover sound came out a
snippet per keystroke rather than fading.

Twelve ticks, which is a second and a half and covers the measured tail
with room over. It is a number about THESE FOUR INSTRUMENTS: a patch with
a longer release would want more, and the general answer is for the
system to quieten the device when a program stops, the way it puts the
screen back. That is not built and is worth deciding on rather than
guessing at.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW

Programs/CosmOS/Apps/Play.asm

@@ -113,9 +113,23 @@ tickLoop:
   BRI tickLoop
 
 finished:
-  ; Let the last note ring rather than cutting it off, then give the timer back - stopped
-  ; before the handler goes away, because an interrupt with nothing to catch it is a fault.
-  INIB 0d8
+  ; ---- Let the last note finish, and MEASURE how long that takes ----
+  ;
+  ; The gates all went down on the tick the tracks ended, but a gate down is a note released
+  ; rather than a note stopped: the oboe and the strings have a release to run. Rendered and
+  ; measured, the tail dies out eight tenths of a second after the last event, and eight ticks
+  ; of ring is one second - which sounds like enough and is two tenths short of it.
+  ;
+  ; A program that exits with sound still in the air leaves nothing able to end it: the
+  ; program is gone and cannot drop a gate. What that turns into depends on the front end -
+  ; behind a window the tail simply finishes, and on a terminal EMULATED TIME STOPS while the
+  ; machine blocks on a key, so the tail freezes and comes out a snippet per keystroke.
+  ;
+  ; Twelve ticks is a second and a half, which covers the measured tail with room over. It is
+  ; a number about THESE FOUR INSTRUMENTS, and a patch with a longer release would want more -
+  ; the general answer is for the system to quieten the device when a program stops, the way
+  ; it puts the screen back, and that is not built.
+  INIB 0d12
 lastRing:
   WAIT
   DECB