diff --git a/docs/re/BACKLOG.md b/docs/re/BACKLOG.md
index 5a9f3bd8..b8ad18d1 100644
--- a/docs/re/BACKLOG.md
+++ b/docs/re/BACKLOG.md
@@ -478,6 +478,30 @@ unknown, what evidence exists, and what the first step would be. Move an item in
   🟡 Not settled: what the kind **means**. The gate is read; the value's domain is
   not, and chasing it needs another hop up (`sub_821A6CF0`'s caller).
 
+* ✅🟡 **(2026-08-27) THE CODE REGION IS NAMED — `GamePart_MainGame` — and the
+  kind's domain has a better-controlled lead that I am NOT adopting.
+  [structures/isl-condition-builtins](structures/isl-condition-builtins.md).**
+  ✅ `sub_821A6CF0` has no `bl` callers, only a tail `b` from `0x821AC04C`, which
+  sits in a run of adjustor thunks fed by a **vtable at `0x820A319C`** (RTTI at
+  `0x820A3198`). **Slot 1 is `addi r3, r0, 17; blr`** — the factory id, and
+  `RegisterToFactory<17, class silph::GamePart_MainGame>` names it. Every thunk
+  does `lwz r3, 8(r3)` first, so slots 4–10 are **`GamePart_MainGame::Impl`
+  methods**: 4 → `sub_821A6CF0`, 5 → `sub_821A82A0`, 6 → `sub_821A8428`,
+  7 → `sub_821A9DC8`, 8 → `sub_821A9CF0`, **9 → `sub_821AA1B0` (the per-frame
+  Update)**, 10 → `sub_821AB570`. The region several iterations have been reading
+  is now *named* rather than inferred.
+  🟡 **The lead, with its control stated.** The disc carries **28 mission scripts
+  numbered `Stage01`–`Stage16` and `Stage18`–`Stage29` — exactly one gap,
+  Stage17** — and the gate excludes **exactly one value, 16**. Under 0-based
+  indexing `16 ↔ Stage17`, with `<= 32` bounding indices 0…28. Against the
+  refuted GamePart-id reading (**4** values missing from its domain, gate excludes
+  1 → 1-of-4, worthless) this is **1-of-1**. Much tighter — and still
+  coincidence-shaped, so **not adopted**. ▶️ What would settle it: the
+  `Stage%02d` construction site. The image has a generic `'%s%02d'` formatter at
+  `0x820A9C8C`; whether it is fed `index` or `index + 1` decides it outright. Not
+  found this pass, and `grep`ping the extracted disc does not help — the pak names
+  are hashed, so neither `Stage16` nor `Stage17` appears as a plain token.
+
 ## ✅✅ SOLVED — the mission freeze was a modal sign-in dialog (2026-08-26)
 
 `XamShowSigninUI` opens a modal dialog and `xeXamDispatchDialog` blocks the
diff --git a/docs/re/structures/isl-condition-builtins.md b/docs/re/structures/isl-condition-builtins.md
index a56b0b91..f3c72574 100644
--- a/docs/re/structures/isl-condition-builtins.md
+++ b/docs/re/structures/isl-condition-builtins.md
@@ -177,6 +177,48 @@ gaps, not a unique one. Nothing distinguishes it. The reading is not adopted.
 🟡 So what the kind **means** is still open — the gate is now read, but the
 value's domain is not.
 
+## ✅ (2026-08-27) The code region is NAMED: `GamePart_MainGame`
+
+`sub_821A6CF0` has no `bl` callers, only a tail `b` from `0x821AC04C`. That
+address sits in a run of adjustor thunks, and the table pointing at them is a
+**vtable at `0x820A319C`** (RTTI locator at `0x820A3198` = `0x8210BB58`):
+
+| slot | entry | resolves to |
+|---|---|---|
+| 0 | `sub_821ABFA8` | destructor |
+| 1 | `0x821AC040` | **`addi r3, r0, 17; blr`** — returns the factory id |
+| 4 | `0x821AC048` | `lwz r3, 8(r3); b sub_821A6CF0` |
+| 5 | `0x821AC050` | `→ sub_821A82A0` |
+| 6 | `0x821AC058` | `→ sub_821A8428` |
+| 7 | `0x821AC060` | `→ sub_821A9DC8` |
+| 8 | `0x821AC078` | `→ sub_821A9CF0` (guarded `r4 == 9`) |
+| **9** | `0x821AC068` | **`→ sub_821AA1B0`** — the per-frame Update |
+| 10 | `0x821AC070` | `→ sub_821AB570` |
+
+Slot 1 returning **17** is decisive: `RegisterToFactory<17, class
+silph::GamePart_MainGame>`. Every thunk does `lwz r3, 8(r3)` first, so these are
+**`GamePart_MainGame::Impl` methods** reached through the outer class. The code
+region this page has been reading is now named rather than inferred.
+
+## 🟡 A lead on the kind's domain — better-controlled than the last one, still not adopted
+
+The disc carries **28 mission scripts, numbered `Stage01`–`Stage16` and
+`Stage18`–`Stage29`** (as extracted; the corpus's own "all 28 `StageNN.ssb`").
+**Exactly one gap: Stage17.** The gate excludes **exactly one value: 16**. Under
+0-based indexing `16 ↔ Stage17`, and `<= 32` comfortably bounds indices 0…28.
+
+Compare the controls honestly:
+
+| reading | values missing from the domain | gate excludes | match |
+|---|---|---|---|
+| GamePart id (refuted) | **4** — 1, 2, 16, 18 | 1 value | 1-of-4 — worthless |
+| stage index (this) | **1** — Stage17 | 1 value | 1-of-1 |
+
+That is a much tighter fit, and it is *still* coincidence-shaped. **Not adopted.**
+What would settle it: the `Stage%02d` construction site — the image has a generic
+`'%s%02d'` formatter at `0x820A9C8C`, and whether it is fed `index` or
+`index + 1` decides the question outright. Not found this pass.
+
 🟡 Its neighbours belong to the same cluster: `builtin103` reads
 `[phase+10156]` and `[phase+10152]` (9 and 7 writers), and a sibling vtable stub
 clears `[phase+10152]`. The shape is an engine→script status trio, but that is a