BT410 notes 5.3.136: the ammo cook-off, decoded -- the mech has never been able to suffer an ammo explosion

Asking what an AmmoBin does with the gun heat alarm that 5.3.132 brought
to life turned up an entire mechanic that has never run here, dead for
two independent reasons: the watch link was unbound so the mirrored
alarm never left NormalHeat, and our AmmoBin has no Performance at all
where the binary installs one.

The trigger: when the gun a bin feeds goes into HEAT FAILURE, the bin
latches a randomised countdown.  Heat clearing cancels it; expiry
destroys the bin and detonates it.  The damage is authored per round and
scaled by rounds remaining, so a full bin guts the mech and a nearly
empty one barely coughs.  The blast is then SHARED -- divided by the
number of targets, not applied whole to each -- and every victim is
announced with the authentic string "ammo explosion damaging <name>",
which is what confirmed the whole reading.

One identity is deliberately left unpinned: what the collector iterates
and what its 0x4e filter selects.  It is not a classID, and the
per-victim reads look more like damage zones than subsystems.  Guessing
would produce a plausible mechanic that damages the wrong things --
precisely the failure this project keeps catching -- so the collector
gets read first and the whole thing lands in one piece.

Worth noting the shape: two dead systems in series were hiding a third.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

restoration/source410/BT/MECH4.NOTES.md

@@ -660,3 +660,48 @@ Still worth exercising now that the mirror is live: what an AmmoBin does
 with its gun's heat alarm (a cook-off or a feed lockout would be the
 obvious candidates, and the binary is the place to check before assuming
 either).
+
+## 5.3.136 -- THE AMMO COOK-OFF, decoded (the payoff of binding the watchers)
+
+Asking what an AmmoBin does with its now-live gun heat alarm turned up a
+whole mechanic that has never run in our tree, for TWO independent
+reasons: the watch link was unbound (5.3.132) so the mirrored alarm never
+left NormalHeat, AND our `AmmoBin` has no Performance at all -- the
+binary installs one (ctor @004bd5c4 stores the triple @0x512654 ->
+`@004bd394`, gated master+dynamic as usual).
+
+**The trigger** (@004bd394): when the bin's mirrored heat alarm (+0x140)
+reads 2 = FailureHeat -- i.e. THE GUN IT FEEDS is cooking -- and the bin
+is not already spent (+0x1a8 != 2) and no countdown is pending, it latches
+one: `cookoffAt = now + <randomised delay>` (time from @00414b60, the
+delay through the ftol helper @004dcd94).  If the heat clears the
+countdown is CANCELLED; if it expires the bin destroys itself
+(state alarm -> 1, dirty mark) and detonates.
+
+**The detonation** (@004bd300 -> @004ac274), and the damage is authored
+per round: `damage = roundsRemaining * perRoundDamage (+0x1f4)`, so a full
+bin guts the mech and a nearly empty one barely coughs.  @004ac274 then:
+
+  * drives the bin's own state alarm 2 then 1 with an update mark each,
+  * pins its PRIVATE damage zone to 1.0 (destroyed),
+  * collects a target set by walking @004acfa9(mech, -1) and keeping
+    entries whose `+4` field equals **0x4e**,
+  * **divides the damage by the number of targets** -- the blast is
+    SHARED, not applied whole to each,
+  * dispatches a 100-byte TakeDamage (id 0x12) at each, printing the
+    authentic `"ammo explosion damaging <name>"` for every victim,
+  * finally zeroes the ammo count and sets the bin's 6-level state alarm
+    (+0x194, ctor `FUN_0041b9ec(+0x194, 6)`) to 2.
+
+**THE ONE THING TO PIN BEFORE LANDING**: what @004acfa9 iterates and what
+`+4 == 0x4e` selects.  0x4e is not a classID (those are 0xBBx), and the
+per-victim reads -- a name via `*(+0x15c) + 8` and an index at `+0x13c` --
+look more like DAMAGE ZONES than subsystems.  Getting this wrong would
+produce a plausible mechanic that damages the wrong things, which is
+exactly the failure mode this project keeps catching, so it is decoded no
+further here.  Read @004acfa9 and @004ad03a/@004ad0a4 (the collector and
+its list) first, then land the whole thing in one piece.
+
+Note the shape of the find: two dead systems in series hid a third.  The
+watcher binding did not just fix an alarm -- it exposed that the mech has
+never been able to suffer an ammo explosion.