Syplheed-Reborn/docs/re/live-unit-definitions.md

Live unit definitions from a running Stage 02 (2026-08-12)

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 that works in the box today, because getting there was most of the work.

The recipe that works

Everything must happen inside one blocking foreground call. A process that outlives the call that started it is reaped — nohup, a harness background job and a wait-holding wrapper were all tried and all died within a minute of the turn ending (see the session-lifetime notes).

tools/re-capture/launch_mission.sh fly     # title → LOAD → slot 01 → READY ROOM → TAKE OFF
python3 tools/re-capture/gmem.py find hex:820af844 400   # live definition objects
python3 tools/re-capture/gmem.py words <va> 96           # dump each one

Two environment facts that cost an hour each:

• Audio must be --audio --apu=sdl with SDL_AUDIODRIVER=dummy. There is no PulseAudio server in the box, so muting (--apu=nop, run-canary's default) looks like the safe choice. It is not: the log then fills with AudioSystem::RegisterClient: CreateDriver failed for index=0, the guest never gets past the movie, and the window stays black for 8+ minutes. nav_probe.sh and launch_mission.sh already pass the right pair — do not "fix" them.
• Boot is fast once the caches are warm. The first boot took minutes; with the shader/code cache populated, launch_mission.sh reached the flight HUD in 25 s, which is what makes a launch-and-dump fit in a single call.

entities2.py, flight_probe.py and the other analysis scripts do not run here — no numpy (and no PIL for image work). gmem.py is pure stdlib and works, so the pattern is: dump raw words to disc inside the call, analyse afterwards.

What came out

14 live definition objects (vtable 0x820af844), 96 words each: captures/stage02-live-unit-definitions.txt, with the flight screenshot they were taken from.

object	+0x30	+0x34	+0x38	+0x54
0xbd3b6a00	2500	3100	2600	10000
0xbd3d2d80	80	80	350	4000
0xbd3da100	10	7	29	1500
0xbd3db980	350	70	200	10000
0xbd3dbd00	10	5	20	300
0xbd3dea80	20	9	22	100
0xbd3dfc00	10	7	29	1000
0xbd3e0680	300	300	2800	3000
0xbd3e1f00	400	400	1400	25000
0xbd3e6f80	300	300	2100	10000
0xbd3ee300	200	200	2000	10000
0xbd3faa80	100	40	50	500
0xbd3fd800	600	600	3800	30000
0xbd40e200	700	700	3800	30000

This corroborates the layout solved earlier from a single in-mission snapshot (+0x054 = HP, +0x30…0x38 = Size_X/Y/Z) rather than re-proving it: the +0x54 column reads as hull values across three orders of magnitude (100 for something small, 30 000 twice for capital ships), and the sizes scale with them. It also gives independent support to the Size_Y inherits Size_X default rule — five of the fourteen have +0x30 == +0x34 exactly (300/300, 400/400, 200/200, 600/600, 700/700) while the rest differ.

Identity without a name: match on the values

Nothing in the first 96 words is a name pointer, so identity comes from the numbers themselves. examples/unit_signatures.rs prints (HP, Size_X, Size_Y, Size_Z) for every craft unit and vessel on the disc; a live object is then the record whose known fields it reproduces exactly.

Seven of the fourteen match a disc record on all four values — the player's Delta Saber (10, 7, 29, HP 1500 in its player form and 1000 otherwise), the ArrowHead, an ADAN turret, an Attacker. The other seven match nothing, and that is the point: their disc records leave a field defaulted, so there is nothing to match against. 18 of the 23 vessel records on disc are missing at least one of these four fields, nearly always Size_Y.

✅ Route B: 13 defaulted fields read out of the running game

Matching each disc record that defaults exactly one field against the live object that reproduces its remaining fields resolves the missing value:

unit	field	runtime value	live object (sx, sy, sz, hp)
UN_e201_ADAN_ISCMissile	Size_Y	300	0xbd3e0680 (300, 300, 2800, 3000)
UN_f106_TCAF_Destroyer	Size_Y	200	0xbd3ee300 (200, 200, 2000, 10000)
UN_f106_TCAF_Destroyer_Inv	Size_Y	200	0xbd3ee300
UN_e105_ADAN_Cruiser	Size_Y	600	0xbd3fd800 (600, 600, 3800, 30000)
UN_e105_ADAN_CruiserEX	Size_Y	600	0xbd3fd800
UN_f105_TCAF_Cruiser	Size_Y	700	0xbd40e200 (700, 700, 3800, 30000)
UN_f105_TCAF_Cruiser_EX5	Size_Y	700	0xbd40e200
UN_f105_TCAF_Cruiser_Inv	Size_Y	700	0xbd40e200
UN_e108_ADAN_ASFrigate	Size_Y	80	0xbd3d2d80 (80, 80, 350, 4000)
UN_e108_ADAN_ASFrigateEX	Size_Y	80	0xbd3d2d80
UN_e106_ADAN_Destroyer	Size_Y	300	0xbd3e6f80 (300, 300, 2100, 10000)
UN_e106_ADAN_DestroyerEX	Size_Y	300	0xbd3e6f80
UN_f101_TCAF_Acropolis	Size_Y	400	0xbd3e1f00 (400, 400, 1400, 25000)

Every resolved value equals that unit's Size_X — so the running game confirms the Size_Y inherits Size_X rule that was derived statically from sibling records, this time from the engine's own parsed definitions.

Two honest limits. Variants share a live object (_Inv, _EX5, EX map to the same definition as their base), so the snapshot cannot distinguish them — the value is right for the class, and per-variant differences in other fields are not addressed. And this run only reaches the units Stage 02 instantiates: the …Ratio / …Count family (HQRatio, PowerRatio, ShieldRatio, HatchCount, NodeCount, SequencingCount, …) is defaulted on 5–23 records each and is not resolved here, because those fields' offsets in the live object are not yet known. Finding them is the next run: dump deeper than 96 words and look for the constants the disc does set on the records that set them.

Locating fields inside the live object

The next step — reading the …Ratio / …Count family — needs to know where each field sits in the live object. The method is to anchor on a unit whose disc record sets a field and look for that value in its dumped words. Anchoring on UN_f106_TCAF_Destroyer (disc sets Size_Radius 0.1, ThrusterRatio 0.8, ResistanceParalyze 0.97) and then checking the same offsets across five capital ships and the player's fighter:

offset	reading	f106	f105	e105	e106	f101	Delta Saber
+0x30	Size_X ✅	200	700	600	300	400	10
+0x34	Size_Y ✅	200	700	600	300	400	7
+0x38	Size_Z ✅	2000	3800	3800	2100	1400	29
+0x54	HP ✅	10000	30000	30000	10000	25000	1500
+0x74	🟡 ThrusterRatio	0.8	0.8	0.8	0.8	0.8	1
+0x84	🟡 ResistanceParalyze	0.97	0.97	0.97	0.97	0.97	0.97
+0x40	❔	0.1	0.1	1	1	1	0.1

+0x74 and +0x84 are marked 🟡 because they rest on one anchoring unit: the value is right for the Destroyer and constant across the others, which is consistent with a field the rest default, but a second anchoring unit that sets them to something different is what would prove it. +0x40 is 0.1 on two units and 1 on three, so it is a real per-unit field — just not identified.

⚠️ The automated version finds almost nothing, and the reason is not what it first looked like. examples/live_offsets.rs correlates every get_f32(key) against every dumped word and keeps offsets all units agree on. Over five units it produced exactly one hit, YawDragFactor → +0x0c, and that hit is wrong: +0x0c holds the integer 2 (printed as the denormal 2.8e-45), which collided with YawDragFactor = 2.0. Any float-compare against small integers has that failure mode.

The first explanation written here — that get_f32 is unreliable on default-heavy records — was wrong, and measuring killed it: get_f32 resolves 46–57 numeric fields per unit (Destroyer 46, e105 Cruiser 57, f105 Cruiser 49, e106 Destroyer 51, Acropolis 45). It is the documented, reliable API and it works.

The real problem is that the values are not in this object. Dumping 512 words (2 KB) instead of 96 changes nothing at all: still exactly 4 of ~50 disc values found, for every one of the five units. So the structure at vtable 0x820af844 is not the parsed definition record — it carries the handful of fields above (sizes, HP, a couple of ratios) and the rest of the record lives elsewhere, presumably behind a pointer.

Next probe, therefore, is not a bigger window: search guest RAM for a value that is distinctive to one unit (e.g. the Acropolis' HP 25000 = 0x46c35000) and see what other structure holds it, then map that one.

Where the rest of the record is — three probes, and a hypothesis

Following "search RAM for a unit-distinctive value" produced no parsed record:

1. HP 25000 (0x46c35000, the Acropolis) — 200+ hits, the search limit. Too common to anchor on: it is also a generic constant.
2. AttackVesselPoint 0.08 (0x3da3d70a, an unusual float) — 64+ hits, and none of the eight windows dumped around them contained the unit's other values (Size_X 400, Size_Z 1400, HP 25000, RadarRange 60000). One hit sits in the executable range (0x820b62f4), i.e. a code/rdata constant.
3. The ID string itself. UN_f101_TCAF_Acropolis appears twice in RAM, each copy referenced by a pointer exactly 16 bytes before the string. But a 256-word window around it contains none of the unit's numbers — because that region is the IDXD string pool, where 25000.0 is stored as text.

🟡 Hypothesis: there is no flat parsed record. IDXD is a reflective format, and the evidence fits the engine reading values out of the pool by key when it needs them, caching only the few it touches per frame. That is exactly what the 0x820af844 object looks like: sizes (collision), HP (damage), a couple of ratios — and nothing else, no matter how deep it is dumped.

If that is right, it reframes Route B. For a defaulted field there is no value in the pool at all, so the default is applied by code at read time and can never be found by scanning data structures. It would have to come from either the read path (trace where a key hash is looked up and what the miss path substitutes) or from the title's own code — which is the DuckDB static route this project already has. The 13 Size_Y values recovered above worked precisely because Size_Y is one of the cached, every-frame fields.

This is a hypothesis, not a finding: it explains three negative probes but has not been confirmed by watching a read happen.

The static route says where the defaults must be

The DuckDB image (xenia-rs/sylpheed.db, 12 156 functions / 1.87 M instructions) has the reflective machinery under real names:

address	name
0x824486c0	IdxdLoad_Dispatch
0x82448d00	IdxdLoad_Variant2
0x82449640	Idxd_Parse
0x8244a2f0	Reflect_FindFieldIndex
0x8244a4b0	Reflect_SetField

Reflect_FindFieldIndex measures a C string, indexes a buffer and calls a compare routine — it looks a field up by name at runtime, which is the reflective read the hypothesis above predicted. But Idxd_Parse is a text parser (it checks for a UTF-16 BOM, walks characters through a jump table at 0x824497f8) and it calls Reflect_SetField on a target object passed in r3.

That last point weakens the "no parsed record" hypothesis: parsing writes values into a real object. So a parsed record does exist — my three RAM probes simply did not find the right one — and, more usefully, it tells us where a defaulted field's value comes from. Idxd_Parse only ever writes the fields the text actually contains, so a defaulted field keeps whatever the object had before parsing — i.e. the value its constructor stored.

So the defaults are neither in the disc data (by definition) nor in a table to be scanned for: they are immediates in the constructor of each definition class. Reading them is a disassembly job — find the allocation site above IdxdLoad_Dispatch, then the constructor it calls, and read the stores. That is the next step, and it would settle the whole …Ratio / …Count family at once rather than one field per flight.

(The vtables, classes and methods tables are empty in this DB build, as CLAUDE.md warns, so the class has to be reached through the call graph.)