re: the "sibling default" rules are a dedup artefact — WITHDRAWN

The corpus recorded that some unit fields the disc leaves defaulted inherit
from a sibling: Size_Y from Size_X, FCSRange from RadarRange, DefencePoint
from AttackVesselPoint. Size_Y was marked the one to trust, on 9/9 support
across 7 independent ships, and it is restated in INDEX.md.

The premise is false. These fields are not defaulted -- they are on disc for
113-114 of 114 unit tables -- and Size_Y DIFFERS from Size_X in 90 of them.

The mechanism, cross-tabulating "legacy reader missed it" against "equal on
disc":

  pair                          seen+differ  seen+equal  miss+differ  miss+equal
  Size_Y / Size_X                    90          0            0           24
  FCSRange / RadarRange              54          0            1           58
  DefencePoint / AttackVesselPoint   51          0            1           61

seen+equal is 0 for all three: a value shared with a sibling is ALWAYS
invisible to the string-pool reader, because the pool stores each distinct
string once. And the reader almost never misses a value that differs. So
"the missing value equals the sibling's" was true BY CONSTRUCTION -- the rule
re-derived the very condition that made the field go missing. That is why the
support looked perfect: it could not fail on the cases it was fitted to.

The two miss+differ cells are its real wrong predictions, both named:
UN_e104_ADAN_Carrier DefencePoint is 0.2 (rule says 0.003), and
UN_e011_ADAN_Attacker_B_HF_Wayne FCSRange is 3000.0 (rule says 6000.0).

Retracted in unit-struct-runtime.md (original reasoning kept below the
correction), live-unit-definitions.md and INDEX.md. Pinned by a disc test
that asserts the seen+equal cells stay zero, so the mechanism itself is
guarded, not just the counts. Artifact: examples/sibling_rule_check.rs.

This one was found by my own check after the subagent assigned to it stalled.

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

docs/re/INDEX.md

@@ -22,7 +22,7 @@ Promote to a prose `structures/…md` file when a format needs behavioural notes
 | XBG7 mesh | ✅/🟡 | `sylpheed-formats/src/mesh.rs` + `tests/mesh_disc.rs` ([xbg7](structures/xbg7-mesh.md)) | **6 294 resources, 6 209 decode (98.7 %), 82 searched-and-missed** (2026-08-12, up from 5 480 / 87.1 %). Five evidence-driven fixes got there: **distinct anchor assignment** (no two resources may claim one buffer — proved by a capture showing the container holds both mirrored `e106` hull halves), the connectivity cap replaced by a **winding-consistency gate at 0.70**, **structural requirements on pre-pivot sub-meshes** (index range, then exact pool coverage), and **filtering after the assignment** so a subset query cannot differ from the full decode. Validated against a runtime capture that names the file offset of every buffer the engine drew: **46/46 drawn buffers claimed, 45 anchored exactly**. **No real mesh now decodes differently in different containers** — all 89 remaining cross-container disagreements are interchangeable 24-vertex bounding boxes, which no anchoring rule can pin (monotone order re-tested and refuted). Remaining misses attribute to the degeneracy/extent gate (42), winding (31) and coverage (9); the first was probed and its "obvious" fix refuted. Every decoded sub-mesh covers its own vertex pool. **The `[index buffer][vertex buffer]` layout is now runtime-verified** (2026-08-13): with the F10 capture extended to log each draw's index buffer, all **42** drawn `Stage_S02` buffers match our decoded index count exactly, all 42 have their index union cover the pool exactly, and the 30 single-block cases all sit at `pad ≤ 3` — so `e106_eng_02_l`'s old rejection was the connectivity gate, not a misplaced index buffer. The `indices=` mystery was the capture keeping only the **first of several index batches** per buffer. **And comparing index VALUES found the biggest silent defect yet**: the anchor took the first `pad` that validated, so a block whose index data sits at pad 2 was read **one element late** — 76/93 captured runs matched, all 17 differences a one-element shift. Scoring pads by degenerate triangles + winding fixes it: **93/93** captured runs now match byte for byte, disc-wide degenerate runs **582 → 1** (the grouped path had the same bug; and two resources were anchored on a degenerate lookalike earlier in file order), **590 of 8 850** sub-meshes re-wired with 10 vertex anchors moved, resources decoded unchanged at 6 209. Cross-container minority decodes 89 → 96 — *because* the decoder improved: `_rou_f402_dead` now has a majority (32×25×8) so its seven wrong copies are named instead of hidden. One dirty run remains, blocked by distinct assignment on a 24-vertex box. **Then the descriptor gave up its last structural secret**: it declares a vertex layout **per sub-mesh** (`n201_01` → strides 24/24/24/**28**, capture-confirmed), and grouped selection must prefer the candidate explaining the **whole** pool rather than the first whose pivot validates — together they take never-decoding resources **85 → 47** (**6 247 / 6 294 = 99.25 %** decode), put `n201_01` on all four capture-proven offsets and raise the stage-05 capture oracle to **128/128**. The residual 47 is 30 pose/proxy composites (0.010-unit marker boxes), 6 `.DAT` particle composites, 8 damage/LOD variants and 3 props — not a threshold away |
 | Capital-ship part placement | ✅ | `sylpheed-formats/src/ship.rs` (static) + [runtime capture](ship-placement-runtime-capture.md) | Placement is **sound** (hull static-exact against the `e106` capture; cross-id mounting genuinely narrow, 2 pairs across 335 ships). The XBG7 mis-decode this row used to blame for "ships assemble wrong" — a shared turret ~100× too large in some containers — is **fixed** (2026-08-12, the exact-coverage requirement): `e303_wep_01` now decodes 49×23×42 everywhere and places at ±179 on the `e106` hull, and no real mesh disagrees across containers. A composite-node audit confirmed the assembler itself never applied a bad scale (all nodes scale 1.0, orthonormal). Still open: `static_assembly_matches_runtime_capture` walks capture parts only, so **extra** static placements cannot fail it |
 | Weapon fields defaulted on disc | ✅ | [runtime struct](structures/weapon-struct-runtime.md) · [DATA SHEET route](weapon-datasheet-runtime.md) | **Solved.** Canary maps guest RAM into `/dev/shm`, so the parsed `Weapon`/`Shell` objects are readable live; their layout is solved against disc ground truth (zero contradictions over 100+ records). All 126 weapons, exact numbers, no story progress needed — [4 393 values](captures/weapon-runtime-fields.csv) the disc does not carry. Supersedes the letter-bucket limit of the DATA SHEET route, which now serves as the independent cross-check |
-| Unit (craft/vessel) fields defaulted on disc | ✅/🟡 | [runtime struct](structures/unit-struct-runtime.md) | The parsed `unit\UN_*.tbl` definition object, vtable `0x820af844`, ≥`0x380` bytes, one per unit — **discovered, not assumed** (`unit_discover.py`), and distinguished from the spawned-entity class `0x820af030` by being one-per-ID and byte-constant within a run. Across runs only pointer words move — `--crosscheck` proves **no reported field offset is run-dependent** (two words, `+0x2c8`/`+0x2d0`, are stage-dependent and remain unidentified). 27 fields ✅ (21 units, 7 runs); the `Maneuver` block is **schema declaration order, 4 bytes/field, base `0x9c` with a two-slot gap after `AA_Roll_Min`** (29 anchors, 0 conflicts), which also pins 5 fields *no* disc record ever values. Angles are **radians at runtime, degrees on disc**. **Re-derived independently 2026-08-13 from the loader's own key strings** (`sub_82341A20`; the field name for each store is a string in the image): **159 fields**, agreeing with this solver on **25 of 25 shared offsets**, verified at **406 values matching the disc and 0 disagreeing** over 11 live objects spanning UNIT and VESSEL — landed as `data/unit_definition_layout.txt` + `sylpheed_formats::unit_layout` + a no-emulator test, with **121 defaulted fields** read out ([live-unit-definitions](live-unit-definitions.md)). Unlike weapons, unit definitions are instantiated **per stage**, so coverage (21/110) grows by visiting missions — but a defaulted field is **not** a global constant: `Size_Y` provably inherits `Size_X` (7 independent units, 6 distinct values), and three more sibling rules are recorded ❔, recovering 65 values in units never visited — [values](captures/unit-runtime-fields.csv) |
+| Unit (craft/vessel) fields defaulted on disc | ✅/🟡 | [runtime struct](structures/unit-struct-runtime.md) | The parsed `unit\UN_*.tbl` definition object, vtable `0x820af844`, ≥`0x380` bytes, one per unit — **discovered, not assumed** (`unit_discover.py`), and distinguished from the spawned-entity class `0x820af030` by being one-per-ID and byte-constant within a run. Across runs only pointer words move — `--crosscheck` proves **no reported field offset is run-dependent** (two words, `+0x2c8`/`+0x2d0`, are stage-dependent and remain unidentified). 27 fields ✅ (21 units, 7 runs); the `Maneuver` block is **schema declaration order, 4 bytes/field, base `0x9c` with a two-slot gap after `AA_Roll_Min`** (29 anchors, 0 conflicts), which also pins 5 fields *no* disc record ever values. Angles are **radians at runtime, degrees on disc**. **Re-derived independently 2026-08-13 from the loader's own key strings** (`sub_82341A20`; the field name for each store is a string in the image): **159 fields**, agreeing with this solver on **25 of 25 shared offsets**, verified at **406 values matching the disc and 0 disagreeing** over 11 live objects spanning UNIT and VESSEL — landed as `data/unit_definition_layout.txt` + `sylpheed_formats::unit_layout` + a no-emulator test, with **121 defaulted fields** read out ([live-unit-definitions](live-unit-definitions.md)). Unlike weapons, unit definitions are instantiated **per stage**, so coverage (21/110) grows by visiting missions — ❌ **the sibling-default rules are WITHDRAWN (2026-08-25)** — `Size_Y` is on disc for **114/114** unit tables and **differs from `Size_X` in 90**; the old reader missed it exactly when the two were equal (a string-pool dedup artefact, cross-tab `seen+equal = 0` for all three pairs), so the rule was re-deriving the condition that hid the field. It also predicts wrong twice — `UN_e104_ADAN_Carrier.DefencePoint` and `UN_e011_ADAN_Attacker_B_HF_Wayne.FCSRange`. Read the record table instead — [values](captures/unit-runtime-fields.csv) |
 | Arsenal develop economy | ✅/❔ | [arsenal-develop-economy](arsenal-develop-economy.md) + [conditions](captures/arsenal-develop-conditions.csv) | The Arsenal reads `weapon.tbl` (item ids, in the 8-category display order) and `strings.tbl` (names, descriptions, and a **"Conditions to obtain"** block per item) out of `GP_HANGAR_ARSENAL.pak`. All **60** conditions are extracted: gates are stage completion, a predecessor item, or an **ace kill**; costs run 3 000–350 000 P and **20 items are free** once gated. `weapon.tbl`'s first record reproduces the in-game DATA SHEET exactly (Range D / Power E / Speed – / Weight 0.3 = Light / 4000 P) — later records are unreadable from the string pool alone because IDXD **dedupes repeated values**. Used to identify the save blob's index space, now **solved**: the blob follows **`strings.tbl`'s** order — the display order *plus* the cut items only the localisation file lists (`Adhesive Mine B2A`, `Ballista GSH`, …) — pinned by four hand-written probe saves (9 Stiletto, 21 Falcon, 39 Tomahawk, 48 Jamming System) and closing exactly at index 53. `weapon.tbl`'s id list is **not** the index space; that it is also 54 long is a coincidence, and the two agree only to index 32. The retail save's five unexplained owned entries are the cut items, shipped owned and never rendered |
 | UI screen layout (`.rat`) | ✅/🟡 | [ui-rat-layout](structures/ui-rat-layout.md) | One pak per UI screen; each RATC = one (context × language) build; every `<name>.t32` sprite has a `<name>.rat` **layout record** (BE u32; 1280×720 design space; scale/tint/X/Y, keyframes for animated elements, `opt ` link to the focused state). **The tutorial PAUSE menu and the title main menu both rebuild pixel-accurately from the disc.** `loop1.rat` is decoded — it is a **looping sprite animation**, not a composition. ⚠️ **DEMOTED 2026-08-18** — the declaration table is *not* the paint order: a per-draw capture of the running title screen ([ui-title-paint-order-capture](ui-title-paint-order-capture.md)) paints element 13 first and elements 0/1 late, and the visible screen composites two bundles. The rest of the table's reading stands. Previously claimed: the **screen's draw list is the RATC bundle's own declaration table** (elements in back-to-front order, including the `eff*`/`deli*`/`msg` sprites that have no `.rat`, and excluding focused button variants reached via `opt `); its entry also carries a **parent element index** at `+32`. **A screen is fully reconstructible from its bundle**: the placement region right after the declaration table gives every element a keyframe group (header = element index + keyframe count, then 40-byte blocks of scale/tint/X/Y), including the `.rat`-less sprites — verified 11/11 on the tutorial pause bundle, with `pgp_ttrl_btn10`'s inline (546,288) matching its own record exactly |
 | UI screen paint order | ✅ | [runtime screen object](structures/ui-screen-runtime.md) + [title capture](ui-title-paint-order-capture.md) | **SOLVED**: the game's screen object keeps a second, reordered list of its elements — the child array at `+0x30` — and that is the paint order, not the declaration table. Read live from guest memory (found by the item vtable `0x820b30b4`) and checked against the draw capture: the seven nameable elements sit at child slots 0, 6, 7, 13, 16, 17, 22, strictly ascending, exactly as captured; it also settles the one pair no static field could order. 🟡 deriving that order from the bundle — what the port needs — is still open |

docs/re/live-unit-definitions.md

@@ -1,5 +1,13 @@
 # Live unit definitions from a running Stage 02 (2026-08-12)
 
+> ❌ **CORRECTION (2026-08-25):** the **`Size_Y` inherits `Size_X`** rule this
+> file supports is **WITHDRAWN**. `Size_Y` is on disc for **114 / 114** unit
+> tables and **differs** from `Size_X` in **90** of them. The old reader missed
+> it precisely when the two values were equal — a string-pool deduplication
+> artefact, since the pool stores each distinct string once. See
+> [unit-struct-runtime](structures/unit-struct-runtime.md#-withdrawn--some-defaulted-fields-inherit-from-a-sibling).
+
+
 The Route-B question — what value does a field that the disc leaves **defaulted**
 actually take at runtime — needs the game running. This is the first snapshot of
 the parsed definition objects taken straight out of guest RAM, plus the recipe

docs/re/structures/unit-struct-runtime.md

@@ -273,7 +273,57 @@ is no need to play it, and no need to survive it.
 
 Stages captured so far: `Ttrl` (BASIC CONTROLS), Stage 02.
 
-## A defaulted unit field is not a global constant — some inherit from a sibling
+## ❌ WITHDRAWN — "some defaulted fields inherit from a sibling"
+
+**The rules below are a string-pool DEDUPLICATION ARTEFACT. The fields were never
+defaulted: they are on disc for 113–114 of 114 unit tables.** Measured
+2026-08-25 against the [record table](idxd-container.md), which the old reader
+could not see; artifact `examples/sibling_rule_check.rs`.
+
+The premise was that these fields are absent from the disc. They are not:
+
+| field | present on disc | **differs** from its claimed parent |
+|---|---|---|
+| `Size_Y` vs `Size_X` | **114 / 114** | **90** |
+| `FCSRange` vs `RadarRange` | 113 / 113 | 55 |
+| `DefencePoint` vs `AttackVesselPoint` | 113 / 113 | 52 |
+
+So `Size_Y` does not "inherit" `Size_X` — it differs from it in 90 of 114 units.
+
+### Why the rules nevertheless *worked*
+
+The old reader infers a value from string-pool adjacency, and the pool stores
+each distinct string **once**. So a field whose value equals a sibling's
+contributes no token of its own and reads as absent. Cross-tabulating "reader
+missed it" against "equal on disc" makes the mechanism exact:
+
+| pair | seen + differ | seen + equal | **missed + differ** | missed + equal |
+|---|---|---|---|---|
+| `Size_Y` / `Size_X` | 90 | **0** | **0** | 24 |
+| `FCSRange` / `RadarRange` | 54 | **0** | 1 | 58 |
+| `DefencePoint` / `AttackVesselPoint` | 51 | **0** | 1 | 61 |
+
+`seen + equal = 0` everywhere: a shared value is *always* invisible to the old
+reader. And it almost never misses a field whose value differs. So "the missing
+value equals the sibling's" was true **by construction** — the rule was
+re-deriving the condition under which the field went missing in the first place.
+
+That is why it looked so strong: 9/9, 4/4, 6/6 support. It could not have
+failed on the cases it was fitted to.
+
+### The two places it does fail
+
+The `missed + differ` cells are the rule's wrong predictions, and both are real:
+
+* `UN_e104_ADAN_Carrier` — `DefencePoint` is **0.2**; the rule predicts
+  `AttackVesselPoint` = 0.003.
+* `UN_e011_ADAN_Attacker_B_HF_Wayne` — `FCSRange` is **3000.0**; the rule
+  predicts `RadarRange` = 6000.0.
+
+**Use the record table.** The rules are unnecessary where they are right and
+wrong where they are not.
+
+### The original text, kept for the reasoning
 
 **Confidence: 🟡 for `Size_Y`, ❔ for the rest. Analysis 2026-08-10, offline, from
 [`captures/unit-runtime-fields.csv`](../captures/unit-runtime-fields.csv).**