re: the chatter phase merge is not additive; 224 authored variants never play

sub_82215A58 reads CrewCount + PresetMessage_Phase1/2/3 and reaches the loader
from ONE call site, so the three phase tables fold into one map keyed by the
event record name.  Every merge collides; sub_82213840 reconciles on the
message list plus +16/+17/+18/+20/+24/+28 (NOT the +32 Yes mask), and the
incumbent always wins.  Measured: 26432 collisions, 26208 identical, 224
different (189 differ only in the message list), 0 mask-only differences.

Refuted handle: intersecting functions by the object's offsets finds dozens of
unrelated layouts -- offset shape is not an identifier.

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

docs/re/structures/preset-message-rules.md

@@ -265,13 +265,71 @@ can never reach, because it skips the record first. Thirteen dead records out of
 
 ### 🟡 What this does *not* settle
 
-The loader tells us the units and the storage, not the policy. `Priority`'s
-comparison rule, whether `Interval` is a cooldown per event or per speaker, and
-what `IntervalFluctuation` randomises against are all in the *consumer* of the
-40-byte object, which this iteration did not read. `Pattern`'s two live values
+The loader and the merge tell us units, storage and duplicate handling — not
+the *firing* policy. `Priority`'s comparison rule, whether `Interval` is a
+cooldown per event or per speaker, and what `IntervalFluctuation` randomises
+against all live in the consumer of the map, reachable via
+`sub_82215A58` ← `sub_82214050`. 🔴 One handle was tried and refuted: searching
+for functions that touch `+16`/`+17`/`+18`/`+20`/`+28`/`+32`/`+36` returns
+dozens of unrelated matches, because those offsets recur across unrelated object
+layouts. Offset shape is not an identifier. `Pattern`'s two live values
 are named, but that `Window` means an on-screen text window is a reading of the
 name, not something measured.
 
+## ✅ How the three phase tables are merged — and what that costs
+
+**Settled 2026-08-27.** `sub_82215A58` is the `UnitMessageSet` reader: it
+references exactly `CrewCount`, `PresetMessage_Phase1`, `PresetMessage_Phase2`
+and `PresetMessage_Phase3`, and it reaches the loader from **one** call site
+(`0x82215D98`). So a crew's three phase tables are loaded into **one** map, not
+three. The map is keyed by a hash of the *event record's name*
+(`sub_82455C78`, the rolling-accumulator / character-sum-top-byte shape
+[`idxd-tag-hash.md`](idxd-tag-hash.md) documents; which member of that family
+this entry point is was not pinned here, and the finding does not depend on it).
+
+Because all 64 event names recur in every phase table, **every merge collides**.
+`sub_82213980`'s insert therefore has a reconciliation arm, and
+`sub_82213840` — a function called from nowhere else — is its comparator.
+
+### `sub_82213840` compares six of the eight fields
+
+It walks the two message-id vectors elementwise, then compares `+16`
+(`Probability`), `+17` (`Priority`), `+18` (`Pattern`), `+20` (`Interval`),
+`+24` (`IntervalFluctuation`) and `+28` (`EffectiveTime`), and returns a bool.
+It does **not** look at `+32` (the `Yes` mask) or `+36`.
+
+On a colliding key the loader compares, and then — whatever the answer —
+**frees the newcomer and keeps the incumbent**. A mismatch additionally clears
+the byte the loader returns (`lbz r3, 80(r31)` at the epilogue); the caller
+turns that into a flag at `0x82215D9C`…`0x82215DDC` and propagates it.
+
+### What the disc actually does with that
+
+Measured over the 22 `UnitMessageSet_S<NN>.tbl` (numbers in the artefact):
+
+| | |
+|---|---|
+| `UnitMessageSet` records naming ≥ 2 phase tables | **298** |
+| duplicate-key insertions to reconcile | **26 432** |
+| identical on the compared fields | **26 208** (99.15 %) |
+| **different** — loader clears its flag | **224** |
+| compared fields equal but `Yes` mask differs | **0** |
+
+Of the 224, **189 differ only in the message list** — per-phase dialogue
+variants for the same event and the same timings. The other 35 also move
+`Probability`/`Priority`/`Pattern`/`Interval`.
+
+✅ **The phase tables are not additive.** For a given crew and event, phase 1's
+rule wins and the later phases' are discarded — so **224 authored variants never
+play**. A port that merges them additively, or that lets a later phase override,
+will not behave like the game.
+
+✅ **The comparator's blind spot is never exercised.** There is no record pair
+that agrees on the six compared fields and disagrees on the `Yes` mask, so the
+fact that `+32` is excluded from the comparison changes nothing on the shipped
+disc. Worth recording precisely because it is the kind of gap that looks like a
+latent bug until it is counted.
+
 ## 🟡 Not settled
 
 * The *policy* the seven fields drive — see "what this does not settle" above.