# Runtime `Unit` struct (craft / vessel definitions) — read from live guest memory

**Confidence: ✅ CONFIRMED** for the 27 fields marked ✅ below (each binding is
reproduced by 10–21 independent disc records, on ≥3 distinct values, with
**zero** contradictions), plus the Maneuver block's declaration-order layout
(29 anchors, two bases, no conflicts). 🟡 PROBABLE for the fields interpolated
between confirmed anchors. 🟡/❔ for the thin single-value bindings, which are
listed but must not be trusted yet.

Captured 2026-07-29 from Xenia Canary running the retail disc in the sylph-re
container: **all six tutorials** and **Stage 02 "Declaration of War"** loaded
from save slot 01. 21 of the disc's 110 units, over 7 snapshots from 7 separate
emulator runs.

## Why this exists

Craft stats were the one Route-B target the previous two passes could not
reach. The Hangar exposes only `Gross Weight` (a class, not a number), and
[the menu route](../weapon-datasheet-runtime.md) has no surface at all for the
flight model. From the memory side, menus were equally useless: **only the
player craft's name string is resident there — the definition objects do not
exist until a mission loads.**

They do exist in-mission. This documents their layout and the values the disc
leaves defaulted.

## Finding the class (discovered, not assumed)

[`tools/re-capture/unit_discover.py`](../../../tools/re-capture/unit_discover.py)
takes no vtable as input. It locates every disc unit-ID string in a memory
snapshot, finds every aligned word pointing at `string_va - d` for a range of
`d`, and tallies the word at `pointer_site - k` across **distinct** unit IDs.
One `(d, k, word)` combination wins by a wide margin:

| δ (name-record → string) | ID pointer at | word | distinct units |
|---|---|---|---|
| `0x10` | object `+0x04` | `0x820af030` | 4 |
| `0x10` | object `+0x04` | `0x820af844` | 4 |

— i.e. exactly the `Weapon` shape: the object holds a name-record pointer at
`+0x04`, and the ID string sits at `name_record + 0x10`.

The two vtables are **two different things**, and telling them apart matters:

| vtable | what it is | evidence |
|---|---|---|
| `0x820af030` | **spawned entity record** — one per spawned thing, but **not live state** (see below) | 12 objects for 4 IDs; the same ID appears many times (one per box in the scene); irregular spacing |
| `0x820af844` | **parsed definition** — the `.tbl` | exactly one object per distinct unit ID; minimum spacing `0x380` |

**Correction (2026-07-29, from the autopilot work):** `0x820af030` was
described here as holding live state. It does not — across a 29 s in-flight
capture **all 384 words of it are constant**. It is one record per spawned
thing, but the flying entity's transform is somewhere else entirely. See
[autopilot-memory-driven](../autopilot-memory-driven.md). Nothing below depends
on it; the definition class `0x820af844` is unaffected.

Only `0x820af844` is used. It is the runtime image of the `.tbl`:

* **Within one run** it is byte-identical across two snapshots taken ~12 minutes
  apart with combat in between (14/14 objects, 0 differing bytes) — definition
  data, not live state.
* **Across runs** the same unit is *not* byte-identical, and that had to be
  explained rather than waved away. `unit_runtime.py --crosscheck` compares
  every unit that appears in more than one snapshot (5 of them, over 7 runs):
  exactly **15 words differ**, and 13 of them hold guest pointers
  (`0x8xxxxxxx`/`0xbxxxxxxx` — heap addresses, which move per process).
  **No solved or interpolated field offset is among the 15** — every value
  reported here is run-invariant.
* The two non-pointer stragglers, `+0x2c8` and `+0x2d0`, are **stage-dependent**:
  for one and the same unit (`UN_f001_TCAF_DeltaSaber_T_Ttrl`) `+0x2c8` reads
  `8000.0` in two tutorials and `10000.0` in a third, with `+0x2d0` a 0/1 flag
  beside it. So the object is *mostly* but not *entirely* the parsed table —
  a couple of words are set per stage. Unidentified; **NEEDS-HUMAN**.

One `.tbl` → **one** object. A unit table is several sub-records (`Generic`,
`Maneuver`, `Shield`, `Explosion`, `Mass`, `Effect`, `SE`, `Turret_00N`), and
they are all flattened into that single ≥`0x380`-byte object — unlike weapons,
where `Weapon` and `Shell` are separate arrays.

## Solving the layout

Same discipline as
[`weapon_runtime.py`](../../../tools/re-capture/weapon_runtime.py): score every
`(field, byte-offset, encoding)` triple against the disc records and accept a
binding only on **zero contradictions**, requiring ≥3 distinct values so a
field whose samples are all one number cannot match any offset holding that
constant.

```bash
python3 tools/re-capture/unit_runtime.py unit_tokens.txt snap_a.bin snap_b.bin --csv
```

Snapshots are **unioned** — each mission instantiates only the units in its own
stage, so coverage grows by visiting stages. `cp --sparse=always` a copy of
`/dev/shm/xenia_memory_*` first (~2 s); the running emulator pegs every core
under lavapipe and makes repeated live reads flaky.

### Encoding note — angles are radians at runtime

Every `AV_*` / `AA_*` / `*Bank*` / `Turn_AngularVelocity` field is stored as
**float32 radians**, while the disc writes **degrees**. The solver needed a
`rad` encoding (`degrees(f32)`) to bind them at all; 18 units agree on
`AV_PitchPlus_Max` alone. A reimplementation reading the `.tbl` must convert.

## Confirmed layout

✅ = ≥10 disc records agree on ≥3 distinct values, zero contradict.

| offset | enc | field | agree | distinct |
|---|---|---|---:|---:|
| `+0x030` | f32 | `Size_X` | 21 | 13 |
| `+0x034` | f32 | `Size_Y` | 12 | 7 |
| `+0x038` | f32 | `Size_Z` | 19 | 13 |
| `+0x040` | f32 | `Color_R` | 21 | 5 |
| `+0x044` | f32 | `Color_G` | 19 | 6 |
| `+0x048` | f32 | `Color_B` | 17 | 5 |
| `+0x050` | f32 | `Size_Radius` | 12 | 10 |
| `+0x054` | f32 | `HP` | 19 | 10 |
| `+0x074` | f32 | `ResistanceToOptics` | 11 | 3 |
| `+0x08c` | f32 | `ScorePoint` | 21 | 9 |
| `+0x094` | f32 | `MassScore` | 10 | 7 |
| `+0x09c` | f32 | `MinimumVelocity` | 11 | 3 |
| `+0x0a0` | f32 | `MaximumVelocity` | 19 | 8 |
| `+0x0a4` | f32 | `CruisingVelocity` | 17 | 7 |
| `+0x0a8` | f32 | `Acceleration` | 18 | 5 |
| `+0x0ac` | f32 | `Deceleration` | 17 | 5 |
| `+0x0b0` | rad | `AV_PitchPlus_Max` | 18 | 7 |
| `+0x0b4` | rad | `AV_PitchPlus_Min` | 10 | 6 |
| `+0x0c4` | rad | `AV_PitchMinus_Min` | 10 | 5 |
| `+0x0f8` | f32 | `SideThrustVelocity_Max` | 14 | 3 |
| `+0x238` | f32 | `MaxValue` (Shield) | 13 | 6 |
| `+0x244` | f32 | `ChargeSpeed` (Shield) | 13 | 6 |
| `+0x270` | f32 | `DestroyMotionTime` | 19 | 7 |
| `+0x2a0` | f32 | `RadarRange` | 18 | 9 |
| `+0x2a4` | f32 | `FCSRange` | 12 | 8 |
| `+0x2b4` | f32 | `AttackVesselPoint` | 14 | 8 |
| `+0x2bc` | f32 | `DefencePoint` | 12 | 7 |

`HQRatio +0x058`, `ShieldRatio +0x05c`,
`ThrusterRatio +0x060`, `ResistanceToShell +0x078`,
`ResistanceToExplosion +0x07c`, `ResistanceToPlayer +0x080`,
`ResistanceParalyze +0x084`, `BridgeCount +0x070` (i32),
`DryMass +0x274`, `GrossMass +0x278`,
`LowerHPThresholdRatio +0x298`, `AttackCraftPoint +0x2b8` bind with zero
contradictions on fewer records or fewer distinct values — 🟡 PROBABLE. The
full solver output is in
[`captures/unit-runtime-fields.csv`](../captures/unit-runtime-fields.csv)
(1 827 values, `conf` column).

## The Maneuver block is laid out in schema declaration order

This is the strongest structural result and it is independent of any single
field's agreement count.

[`schema_order.py`](../../../tools/re-capture/schema_order.py) merges the
`Maneuver` field-name order from **all 113 unit tables** by topological sort
over their pairwise "k[i] precedes k[i+1]" constraints. The merge is acyclic and
**every one of the 113 tables is a subsequence of the merged 102-field order** —
so that order is the schema's.

Against it, the solved offsets fall into two exact runs:

| declaration indices | offset rule | anchors that fit |
|---|---|---|
| 0 … 20 (`MinimumVelocity` … `AA_Roll_Min`) | `0x09c + 4·i` | 21 / 21 |
| 21 … 32 (`SideThrustVelocity_Max` … `AccPitchFactor`) | `0x0a4 + 4·i` | 8 / 8 |

One 4-byte slot per field, with a **two-slot gap after `AA_Roll_Min`**
(`0x0f0`–`0x0f4`, purpose unknown). 29 independently-derived anchors, zero
conflicts, across a 0x9c–0x125 span.

### Fields NO disc record ever values — 🟡 PROBABLE

Five `Maneuver` fields are declared by the schema but left at their default by
*every* one of the 110 unit tables, so no amount of disc analysis can ever
reach them. The declaration-order rule pins them between confirmed anchors
(`YawDragFactor +0x104` … `ArterBurner_Vc +0x114`, and
`ReverseThrust_Vc +0x118` … `ReverseThrust_Acc +0x120`):

| offset | field | craft (`f00*`, `e0*`) | capital ships (`*1**`, `e2*`) | inert (`SchlosBase`, `Box`) |
|---|---|---:|---:|---:|
| `+0x108` | `PitchDragFactor` | 3 | 2 | 0 |
| `+0x10c` | `RollDragFactor` | 3 | 2 | 0 |
| `+0x110` | `DragFactorThreshold` | 0.5 | 0.5 | 0 |
| `+0x11c` | `ArterBurner_Acc` | 2 | 2 | 0 |
| `+0x128` | `DecPitchFactor` | 30 | 30 | 0 |

Corroboration beyond the interpolation, checked over all 18 units:

* `PitchDragFactor == RollDragFactor == YawDragFactor` holds **18/18** — and
  `YawDragFactor` is *disc-supplied* (3.0 for craft, 2.0 for warships), so two
  interpolated offsets reproduce a known number, per unit, every time.
* `DecPitchFactor == AccPitchFactor` holds **17/18**. The exception is
  `UN_e015_ADAN_Puppy` (`AccPitchFactor` 1, `DecPitchFactor` 0.5) — which
  defaults *both* on disc, so it is two independent fields that happen to be
  set equal elsewhere, not a broken binding.

`UN_e015_ADAN_Puppy` also breaks the craft/warship bucketing above for
`DecPitchFactor` (0.5, not 30); the per-unit values are in the CSV.

The tail of the `Maneuver` block (the AI-behaviour fields — `SideRoll_*`,
`BarrelRoll_*`, `TurnAttack_*`, `HoldPosition_*`, `Slalom_*`, `Through_*`,
`SolidCutoff_*`, and the `AxisMode` / `AB_*` sub-block) is **NOT resolved**.
Those fields are declared by only a handful of tables and almost always with a
single distinct value, so the solver's bindings there are coincidences: it
placed `Slalom_CutoffRatio` at `+0x00c` and `TurnAttack_DoubleTimeMin` at
`+0x110`, both of which the declaration-order rule contradicts. They are marked
`tentative` in the CSV. **NEEDS-HUMAN / needs more coverage** — more stages
would give those fields distinct values and settle it.

## The player craft, `UN_f001_TCAF_DeltaSaber_T_Player`

30 of its fields are defaulted on disc. Notable recovered values:

| field | value | note |
|---|---|---|
| `Size_Radius` | 10 | ✅ |
| `FCSRange` | 500000 | ✅ — same as `RadarRange` |
| `ChargeSpeed` (shield) | 25 | ✅ |
| `ResistanceToOptics` | 1 | ✅ |
| `HQRatio` / `ShieldRatio` / `ThrusterRatio` | 1 / 1 / 1 | 🟡 |
| `ResistanceToShell` / `ResistanceToExplosion` | 1 / 1 | 🟡 |
| `DryMass` | 100 | 🟡 (`GrossMass` 250 is on disc) |
| `LowerHPThresholdRatio` | 0.3 | 🟡 |
| `ChargeDelay_Break` | 10 | 🟡 |
| `MassScore` | 0 | 🟡 |

Every AI-behaviour field the solver bound reads **0** for the player craft,
which is the expected shape (the player is not AI-driven) — but see the caveat
above: those offsets are not settled, so treat the zeros as consistent, not
proven.

The `…Ratio` family that the Route-B target list parked is **1.0 for almost
every unit**, with real exceptions that only the runtime shows:
`UN_e105_ADAN_Cruiser` `HQRatio` = 0.2, `UN_bf001_TCAF_SchlosBase` and
`UN_e106_ADAN_Destroyer` `ThrusterRatio` = 0.2,
`UN_n001_TTRL_Box` `ShieldRatio` = 0.3.

## Coverage and how to extend it

21 of 110 units. Unlike weapons — where one snapshot held all 126 — **unit
definitions are instantiated per stage**, so coverage is bounded by the stages
reachable from the save (slot 01 is at 5 %, Stage 02). `unit_runtime.py` unions
any number of snapshots and re-solves, and more units directly promote the 🟡
bindings to ✅ by adding distinct values — the six tutorials took the confirmed
set from 22 fields to 27.

The tutorials are nearly exhausted as a source: all six together contribute only
3 units the missions do not already have (`UN_f001_TCAF_DeltaSaber_T_Ttrl`,
`UN_e015_ADAN_Puppy_2`, `UN_f001_TCAF_DeltaSaber_T_Player_Ttrl2`) — they reuse
one training box, one target drone and the player craft. **Real coverage now
needs real missions**, i.e. story progress on the save.

`tools/re-capture/grab_tutorial.sh` captures one tutorial per invocation
(cold boot → menu → Nth entry → snapshot, ~2.5 min). It cold-boots for each
because backing out of a loaded mission via PAUSE → BACK TO MENU wedges the
emulator. Two timing facts it encodes, both learned the hard way: the main menu
is **not input-ready for ~10 s** after the title tap, and d-pad presses before
that are silently dropped — which sends the A to `NEW GAME` instead of
`TUTORIAL`. And `NEW GAME` is not a cheap way to reach Stage 01: it gates on a
DIFFICULTY menu and then plays the prologue movie.

A NEW GAME excursion as far as the READY ROOM leaves
`535107D4/00000001/game01/savedata` byte-identical — only the profile `.gpd`
achievement files change — so it does not endanger the 5 % save. Verified by
diff against a backup, not assumed.

**A stage's whole unit set is parsed at load, not as waves spawn** — checked by
counting the definition objects at three points in Stage 02: immediately after
take-off, ~12 minutes in mid-combat, and after GAME OVER. 14 objects, the same
14 IDs, every time. So capturing a stage costs one load and one snapshot; there
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

**Confidence: 🟡 for `Size_Y`, ❔ for the rest. Analysis 2026-08-10, offline, from
[`captures/unit-runtime-fields.csv`](../captures/unit-runtime-fields.csv).**

The coverage limit above (21 of 110 units, growing only with story progress) is
worth attacking from the other side first: *if* a field the disc leaves unset
always took the same runtime value, the 21 captured units would pin that default
for all 110 and no further missions would be needed.

**It does not.** Restricting to the 150 values that are both ✅ CONFIRMED and
come from a field the disc leaves defaulted, only 6 of 24 fields have a single
value across every unit that defaults them (`HP`→10, `MassScore`→0,
`MaximumVelocity`→0, `RadarRange`→0, `DestroyMotionTime`→0, `Size_Z`→0.1). The
other 18 take several distinct values — so the default is computed per unit.

Where from? For each defaulted value, ask which *other* field of the same unit
holds exactly that value. Counting only cases where the value is **non-zero**
(otherwise `0 == 0` inflates every pair) and checking that the two fields are at
**different offsets** (so the match is not the layout solver aliasing them):

| defaulted field | takes the value of | support | independent units |
|---|---|---|---|
| `Size_Y` (`0x034`) | `Size_X` (`0x030`) | 9/9 | **7**, 6 distinct values |
| `Size_Radius` (`0x050`) | `min(Size_X, Size_Z)` | 4/4 | 4, 3 distinct values |
| `FCSRange` (`0x2a4`) | `RadarRange` (`0x2a0`) | 4/4 | 2 |
| `DefencePoint` (`0x2bc`) | `AttackVesselPoint` (`0x2b4`) | 6/6 | 2 |

`Size_Y ← Size_X` is the one to trust: seven unrelated ships (`e105` 600,
`e106` 300, `e108` 80, `e201` 300, `f101` 400, `f105` 700, `f106` 200) each omit
`Size_Y` on disc and each shows its own `Size_X` at runtime. When both fields
*are* on disc they differ freely (14 distinct `Size_Y` values against 13 of
`Size_X`), so this is a default rule, not one value stored twice.

`Size_Radius`'s formula is **not yet separable**: `min(Size_X, Size_Z)` and "the
median of the three axes" fit all four units identically. `UN_e010_ADAN_Attacker_S`
is what rules out the simpler `Size_Radius ← Size_X` (X=100, Y=40, Z=50, radius
**50**). The last two rules rest on two independent units each and are ❔ —
recorded so they can be falsified, not relied on.

**Why it matters for the reimplementation:** filling a missing `Size_Y` with `0`
or with a global constant gives the game's largest hulls a wrong lateral extent
(`f105` 700, `e105` 600, `f101` 400 — all defaulted on disc). Applied across the
disc, the rules recover **65 (unit, field) values in units that have never been
visited**: `Size_Y` in 21 of the 21 units that omit it, `Size_Radius` in 22 of 26,
`FCSRange` in 14 of 56, `DefencePoint` in 8 of 60.

### Cross-check against the weapons: this is NOT an engine-wide mechanism

The obvious worry is that four rules from 21 units are coincidence. The
`Weapon`/`Shell` capture is the control: **complete coverage, 126 records**, with
the same "defaulted on disc" classification. Running the identical sweep there
(confirmed rows, non-zero values, offsets required to differ) finds **no sibling
rule at all** — the single 100 %-agreement candidate (`Shell.Length ←
`Shell.Volume`, 5 records) has one distinct value, i.e. it is really the constant
`Length → 10` coinciding with `Volume = 10`. Weapon defaults vary per record just
as unit defaults do (10 of 14 `Weapon` fields, 16 of 17 `Shell` fields), so the
phenomenon is general; the *sibling* explanation is not.

So `Size_Y ← Size_X` is **specific to the unit schema** (plausibly the size block
defaulting its axes), not a property of IDXD default resolution. Two consequences:
the rule cannot be justified by appeal to a general mechanism, and the two
two-unit hypotheses (`FCSRange`, `DefencePoint`) lose the support they would have
borrowed from one — treat them as **coincidence-not-excluded** until a new stage
tests them.

`Size_Y ← Size_X` itself survives this scrutiny, and was re-checked at the raw
token level rather than through the sub-record merge: `UN_e105_ADAN_Cruiser`,
`UN_f105_TCAF_Cruiser` and `UN_f101_TCAF_Acropolis` each declare `Size_X`,
`Size_Z` and `Size_Radius` and **no `Size_Y` at all**, and each reads back its own
`Size_X` (600 / 700 / 400) at runtime.

**How to falsify:** the rules predict a specific number for units in stages not
yet captured. Load any new stage, snapshot, and compare — one disagreement kills
the rule. Note what is *not* a useful test: Stage 01, the only other reachable
stage, adds just four uncaptured units (`e010`/`e106` variants) whose predictions
are the same numbers their already-captured base variants gave, so it would
re-measure rather than test. A real test needs a stage with unfamiliar classes,
i.e. story progress — which is now the *only* thing story progress is needed for
here.
