Stop drawing bullets past the edge of sight -- but never sooner than is safe

Bullets were drawn everywhere on screen, including out in the black past
the edge of sight: shots that could not reach you, streaking across the
dark. They now fade out beyond sight, under one condition that bounds the
whole change: no enemy bullet may hit you without having been on screen,
at full strength, for at least WARNING_TIME (0.75s) first.

So each enemy bullet is drawn out to the edge of sight or to however far
it could close in that window with you running straight at it -- its own
speed, plus acceleration over the window, plus yours -- whichever is
further, and fades over 80 units beyond. With today's content the edge of
sight always wins: the fastest enemy bullet is 300 u/s, so head-on it is
on screen 0.83s before it lands. The speed term is what keeps that true
when something faster is added. Player shots fade at the edge of sight
however fast they are, since they cannot hurt you; a Sniper's 1500 u/s
shot was the commonest thing crossing the dark.

Shadow does not hide a bullet. One behind a wall within sight range is
still drawn over the darkness, because you can step round the corner into
it, and hiding it would be exactly the invisible hit the condition rules
out.

The guarantee is tested the hard way: every emitter in the content, and
bullets far faster than any of them, simulated head-on against a player
running at them, measuring how long each was fully drawn before it
landed. The rule's weakenings -- no speed term, forgetting the player's
own approach, ignoring acceleration -- each fail it. The connect screen's
backdrop passes no eye and draws everything, as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/DECISIONS.md

@@ -108,8 +108,21 @@ stopping at a circle. Nothing is remembered: still hard fog.
 Two lines this deliberately does not cross: light stops the moment a ray steps
 back out of the wall it was in, so it never rounds a corner or reaches the far
 side of a one-tile wall; and two blocking tiles that touch only at a corner are
-closed, not a crack. Bullets are drawn over the darkness, as they always were —
-a shot out of the black is still one you can dodge.
+closed, not a crack. Bullets are drawn over the darkness — a shot out of the
+black is still one you can dodge.
+
+**Bullets fade out past the edge of sight, but never sooner than is safe.**
+*(User asked to stop drawing bullets beyond sight, with the condition that
+nobody is ever hit by a bullet they could not see.)* Every enemy bullet is
+drawn at full strength out to the edge of sight or to however far it could close
+in `BulletRenderer.WARNING_TIME` (0.75s) with you running straight at it,
+whichever is further, then fades over 80 units. Today the edge of sight is always
+further: the fastest enemy bullet is 300 u/s, so even head-on it is on screen
+0.83s before it lands. `test_bullet_draw.gd` checks that for every emitter in the
+content, and for bullets far faster. Player shots fade at the edge of sight
+regardless, since they cannot hurt you. Bullets in shadow *within* sight range
+are still drawn: you can step round a corner into one, and hiding it would be
+exactly the invisible hit the condition rules out.
 
 **Dungeon size scales with depth.** *(User, this session.)* `--depth N` is a dev
 flag; what raises depth in actual play is still open.