re: ISL built-ins 26 / 29 / 101 named end to end; 28's field pinned, label 🟡

The three unnamed built-ins are one family, and the chain from the dispatch
table to the field write is now followed for all of them:

  builtin -> ScriptPhase vtable slot -> interpreter command word 0xAB<op>BA
          -> command-table thunk -> opcode handler -> unit message 0xED08nnDE
          -> the GROUP pump sub_8232C4C0, which rebroadcasts to each child as
             0xED09nnDE
          -> the entity base handler sub_82398CC0, which writes the field.

  26 -> [unit+532]  = min(max(def.HP * pct, 0), def.HP)   = set_unit_hp_pct
  29 -> [unit+676]  = pct, a multiplier on damage TAKEN   = set_unit_damage_taken_pct
  28 -> [unit+672]  = pct, default 1.0                    = 🟡 damage DEALT
 101 -> the same message as 29 with a hard-wired 0.0, broadcast to every unit
        = all_units_invulnerable

`damage_unit` is WITHDRAWN for 26. The handler sets an absolute value rather
than subtracting one, and 100 heals to full -- which no damage primitive does.
It is pinned three ways: [unit+496] is the unit definition (the constructor
sub_82393868 fills it from the same std::map::find built-in 15 uses), [def+84]
is HP in unit_definition_layout.txt and the constructor seeds [unit+532] from
it, and crossing zero loads [def+584] = Delay and raises a flag, i.e. the
destruction sequence. So 0 destroys, with the datasheet's own death delay.

29 is the strongest of the three: [unit+676] has three independent readers
(sub_8237B020, sub_823800A8, sub_82398CC0) and every one multiplies a damage
amount immediately before it reduces [unit+532].

28 is deliberately left 🟡. The write and the 1.0 default are certain, but the
field has exactly ONE reader in the whole image -- the craft update's projectile
spawn, where it ends up as a multiplicative term in the damage message. That is
the mirror of 29 and it is tidy, which is exactly the shape that produced the
wrong names this file has already had to withdraw. What is not established is
that it reaches every weapon; the sibling damage sender sub_82388FF8 has no
+672 term at all.

Three usage tests, all measured over the 28 stages:
  * operand ceilings -- 26 is 97/97 inside [0,100] and 29 is 164/164, while 28
    (identical signature, identical x0.01 conversion) reaches 2000;
  * the craft cross-tab -- 26 splits cleanly into disposable props at 0,
    warships at 30-80 and the tutorial player craft at 100; 29 lands on the
    player, the tutorial boxes and the escorted TCAF hulls; 28 orders
    boss > ace > elite > line > prop;
  * the setup idiom -- activate_unit, then 15/29/28 as a speed/toughness/
    firepower trio, with 26 added wherever a unit must arrive pre-damaged.

Refutations attempted are recorded, including the two that turned into
confirmations (Stage 28 makes each tutorial box invulnerable with 29 and then
removes it with 26) and the offset-search trap that produced three false
readers, because projectiles have their own fields at 672 and 676.

Also corrected: the state guards. 26 rejects states 3 and 4; 28 and 29 reject
1, 3 and 4. This file said otherwise for both.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PMRJjbxLqZtsb5Vb7KunPE

docs/re/INDEX.md

@@ -97,6 +97,7 @@ files, which is how the same ground got covered twice.
 | [`structures/sound-pak-contents.md`](structures/sound-pak-contents.md) | Census of `sound.pak`, and the limit of the leading-region rule | ✅ CONFIRMED, 5 135/5 135 names hash into the TOC and 9 517/9 519 entries accounted for; ⚠️ leading-region rule holds for 1 571/4 382 eng and 0/5 100 jpn |
 | [`structures/sound-cue-table.md`](structures/sound-cue-table.md) | The cue index in `tables.pak` — message id -> cue -> sound id -> `.slb` bank | ✅ CONFIRMED, 1 326/1 338 script message ids bind to a bank; SOUNDS and FILES agree on the same 12 absentees, 0 orphan files |
 | [`structures/cutscene-message-table.md`](structures/cutscene-message-table.md) | Cutscene dialogue — speaker, portrait, on-screen seconds, audio cue per page | ✅ CONFIRMED, field count = 9·PageCount+2 for all 7 PageCounts, 1 252/1 252 caption keys match, 138 ids close both ways |
+| [`structures/isl-builtins.md`](structures/isl-builtins.md) | The 147 ISL built-ins — dispatch table, calling convention, and which one does what | ✅ for the table/ABI and ~135 handlers; ✅ 26 `set_unit_hp_pct`, 29 `set_unit_damage_taken_pct`, 101 `all_units_invulnerable`; 🟡 28 |
 | [`structures/isl-message-dialogue-link.md`](structures/isl-message-dialogue-link.md) | Mission scripts as dialogue — built-in 64 -> message id -> caption text | ✅ CONFIRMED total, 2 683/2 683 call sites across all 28 stages resolve, no residue |
 | [`structures/mission-objective-counter.md`](structures/mission-objective-counter.md) | `REMAINING OB` — the mission's own objective counter, in RAM |  ✅ CONFIRMED for one Stage 02 run: a big-endian u32 whose value |
 | [`structures/movie-subtitles.md`](structures/movie-subtitles.md) | Movie subtitles & the movie ↔ mission ↔ text chain | — |