G2 support

docs/gold-walkthrough/asm-walk/section-30-lapras.md

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+# Section 30 - Lapras
+
+Source: `../section-30-lapras.txt`
+Maps covered: `MAP_UNION_CAVE_1F`, `MAP_UNION_CAVE_B1F`, `MAP_UNION_CAVE_B2F`
+(approach only: `MAP_ROUTE_32`, whose warp into the cave is cited but which
+belongs to section 03)
+Badges / key milestones in this section: no badge. The milestone is the **static
+level-20 Lapras** on Union Cave B2F, which only exists on a Friday and only once
+per in-game day (`ENGINE_UNION_CAVE_LAPRAS`). Five optional trainers
+(Andrew, Calvin, Nick, Gwen, Emma) and two item balls sit on the way in.
+
+This is a *revisit* section: Union Cave 1F/B1F were first walked in section 03.
+Everything here is reachable only with Surf, i.e. after the Fog Badge.
+
+## 1. Route order
+
+| # | Map constant | asm file | Enter via | Leaves via | Why (walkthrough beat) |
+|---|---|---|---|---|---|
+| 1 | `MAP_ROUTE_32` | `maps/Route32.asm` | walked south from Violet City (`connection south, Route32, ROUTE_32, 0` in `data/maps/attributes.asm`) | `warp_event  6, 79, UNION_CAVE_1F, 4` | "head to Violet City and then go south through Route 32 into Union Cave" |
+| 2 | `MAP_UNION_CAVE_1F` | `maps/UnionCave1F.asm` | warp 4 at `17, 3` (from Route 32) | `warp_event  3, 33, UNION_CAVE_B1F, 4` | walk past Daniel / Russell / Bill, surf the south-west lake, take the bottom-left ladder |
+| 3 | `MAP_UNION_CAVE_B1F` | `maps/UnionCaveB1F.asm` | warp 4 at `3, 33` | `warp_event 17, 31, UNION_CAVE_B2F, 1` | Pokemaniac Andrew stands at `5, 32` right next to the arrival ladder; surf east to Calvin at `17, 30`, then the ladder beside him |
+| 4 | `MAP_UNION_CAVE_B2F` | `maps/UnionCaveB2F.asm` | warp 1 at `5, 3` | same warp back up, or Escape Rope / Dig | Hyper Potion, Nick, Gwen, Emma, then the Lapras object at `11, 31` |
+
+The walkthrough ends inside Union Cave B2F ("You can then use Escape Rope to
+leave Union Cave"); it does not spill into a neighbouring section's map.
+
+## 2. Maps
+
+### MAP_UNION_CAVE_1F
+
+- Script: `maps/UnionCave1F.asm`
+- Blocks: `maps/UnionCave1F.blk`
+- Header: `data/maps/maps.asm:107` -> `map UnionCave1F, TILESET_CAVE, CAVE, LANDMARK_UNION_CAVE, MUSIC_UNION_CAVE, TRUE, PALETTE_NITE, FISHGROUP_LAKE`
+  (the `TRUE` field is the phone-service flag: **no phone calls in Union Cave**)
+- Dimensions: `constants/map_constants.asm:94` -> `map_const UNION_CAVE_1F, 10, 18` (10x18 blocks = 20x36 walk cells)
+- Attributes: `data/maps/attributes.asm:426` -> `map_attributes UnionCave1F, UNION_CAVE_1F, $09`
+- Connections: none (no `connection` rows follow the attributes line)
+- Map group: `MapGroup_Dungeons` (`data/maps/maps.asm:77`)
+
+**Warps** (`def_warp_events`)
+
+| idx | x | y | destination map | dest warp |
+|---|---|---|---|---|
+| 1 | 5 | 19 | `UNION_CAVE_B1F` | 3 |
+| 2 | 3 | 33 | `UNION_CAVE_B1F` | 4 |
+| 3 | 17 | 31 | `ROUTE_33` | 1 |
+| 4 | 17 | 3 | `ROUTE_32` | 4 |
+
+**Coord events** (`def_coord_events`)
+
+None - the block is empty.
+
+**BG events** (`def_bg_events`)
+
+None. (`UnionCave1FUnusedSign` / `UnionCave1FUnusedSignText` exist in the file
+but are marked `; unreferenced` and are not in any `bg_event` row.)
+
+**Object events** (`def_object_events`)
+
+| const | sprite | x | y | movement | type | script label | event flag |
+|---|---|---|---|---|---|---|---|
+| `UNIONCAVE1F_POKEFAN_M1` | `SPRITE_POKEFAN_M` | 4 | 4 | `SPRITEMOVEDATA_SPINRANDOM_FAST` | `OBJECTTYPE_TRAINER`, sight 1 | `TrainerHikerDaniel` | -1 |
+| `UNIONCAVE1F_SUPER_NERD` | `SPRITE_SUPER_NERD` | 4 | 21 | `SPRITEMOVEDATA_STANDING_DOWN` | `OBJECTTYPE_TRAINER`, sight 2 | `TrainerPokemaniacLarry` | -1 |
+| `UNIONCAVE1F_POKEFAN_M2` | `SPRITE_POKEFAN_M` | 15 | 8 | `SPRITEMOVEDATA_STANDING_LEFT` | `OBJECTTYPE_TRAINER`, sight 3 | `TrainerHikerRussell` | -1 |
+| `UNIONCAVE1F_FISHER1` | `SPRITE_FISHER` | 16 | 31 | `SPRITEMOVEDATA_STANDING_UP` | `OBJECTTYPE_TRAINER`, sight 4 | `TrainerFirebreatherRay` | -1 |
+| `UNIONCAVE1F_FISHER2` | `SPRITE_FISHER` | 15 | 15 | `SPRITEMOVEDATA_SPINRANDOM_FAST` | `OBJECTTYPE_TRAINER`, sight 2 | `TrainerFirebreatherBill` | -1 |
+| `UNIONCAVE1F_POKE_BALL1` | `SPRITE_POKE_BALL` | 17 | 21 | `SPRITEMOVEDATA_STILL` | `OBJECTTYPE_ITEMBALL` | `UnionCave1FGreatBall` | `EVENT_UNION_CAVE_1F_GREAT_BALL` |
+| `UNIONCAVE1F_POKE_BALL2` | `SPRITE_POKE_BALL` | 4 | 2 | `SPRITEMOVEDATA_STILL` | `OBJECTTYPE_ITEMBALL` | `UnionCave1FPotion` | `EVENT_UNION_CAVE_1F_POTION` |
+| `UNIONCAVE1F_POKE_BALL3` | `SPRITE_POKE_BALL` | 4 | 17 | `SPRITEMOVEDATA_STILL` | `OBJECTTYPE_ITEMBALL` | `UnionCave1FXAttack` | `EVENT_UNION_CAVE_1F_X_ATTACK` |
+| `UNIONCAVE1F_POKE_BALL4` | `SPRITE_POKE_BALL` | 12 | 33 | `SPRITEMOVEDATA_STILL` | `OBJECTTYPE_ITEMBALL` | `UnionCave1FAwakening` | `EVENT_UNION_CAVE_1F_AWAKENING` |
+
+**Scripts of interest**
+
+- `UnionCave1F_MapScripts` - `def_scene_scripts` and `def_callbacks` are both
+  empty. Nothing on 1F is time- or flag-gated; the floor is pure walking.
+- `PokemaniacLarryAfterBattleText` and `FirebreatherBillAfterBattleText` are the
+  in-game hints the walkthrough is acting on: *"Every Friday, you can hear
+  #MON roars from deep inside the cave."* and *"On weekends, you can hear
+  strange roars from deep in the cave."* Only Larry's Friday line matches the
+  code (see B2F callback below).
+
+**Flags and events**
+
+| constant | defined in | read/written by | meaning for a bot |
+|---|---|---|---|
+| `EVENT_UNION_CAVE_1F_GREAT_BALL` | `constants/event_flags.asm` | itemball object row | set once the ball is taken; masks the object |
+| `EVENT_UNION_CAVE_1F_POTION` | `constants/event_flags.asm` | itemball object row | same |
+| `EVENT_UNION_CAVE_1F_X_ATTACK` | `constants/event_flags.asm` | itemball object row | same |
+| `EVENT_UNION_CAVE_1F_AWAKENING` | `constants/event_flags.asm` | itemball object row | same |
+| `EVENT_BEAT_HIKER_DANIEL`, `EVENT_BEAT_HIKER_RUSSELL`, `EVENT_BEAT_POKEMANIAC_LARRY`, `EVENT_BEAT_FIREBREATHER_BILL`, `EVENT_BEAT_FIREBREATHER_RAY` | `constants/event_flags.asm` | 3rd argument of each `trainer` macro row | set = already beaten, no eyesight trigger |
+
+**Items**
+
+| item | how obtained | source (label / bg_event / hidden) | one-time flag |
+|---|---|---|---|
+| `GREAT_BALL` | item ball at 17,21 | `UnionCave1FGreatBall` (`itemball GREAT_BALL`) | `EVENT_UNION_CAVE_1F_GREAT_BALL` |
+| `POTION` | item ball at 4,2 | `UnionCave1FPotion` | `EVENT_UNION_CAVE_1F_POTION` |
+| `X_ATTACK` | item ball at 4,17 | `UnionCave1FXAttack` | `EVENT_UNION_CAVE_1F_X_ATTACK` |
+| `AWAKENING` | item ball at 12,33 | `UnionCave1FAwakening` | `EVENT_UNION_CAVE_1F_AWAKENING` |
+
+**Trainers** (all optional on this pass; the walkthrough only mentions walking past them)
+
+| const | class | id | party (`data/trainers/parties.asm` label) | script label | rematch/phone |
+|---|---|---|---|---|---|
+| `HIKER`, `DANIEL` | `HIKER` | `DANIEL` | `"DANIEL@"` | `TrainerHikerDaniel` | phone service disabled on this map (`TRUE` in the header) |
+| `HIKER`, `RUSSELL` | `HIKER` | `RUSSELL` | `"RUSSELL@"` | `TrainerHikerRussell` | as above |
+| `POKEMANIAC`, `LARRY` | `POKEMANIAC` | `LARRY` | `"LARRY@"` | `TrainerPokemaniacLarry` | as above |
+| `FIREBREATHER`, `BILL` | `FIREBREATHER` | `BILL` | `"BILL@"` | `TrainerFirebreatherBill` | as above |
+| `FIREBREATHER`, `RAY` | `FIREBREATHER` | `RAY` | `"RAY@"` | `TrainerFirebreatherRay` | as above |
+
+(Party rows for these five were not transcribed - they belong to section 03 and
+the walkthrough tells the bot to walk past them, not fight them.)
+
+**Wild encounters**
+
+Grass/cave, `data/wild/johto_grass.asm:444` `def_grass_wildmons UNION_CAVE_1F`,
+rate `6 percent` for morn/day/nite alike. Gold list (identical across all three
+time slots):
+
+| slot | level | species |
+|---|---|---|
+| 1 | 6 | `GEODUDE` |
+| 2 | 6 | `SANDSHREW` (Silver: `RATTATA`) |
+| 3 | 5 | `ZUBAT` |
+| 4 | 4 | `RATTATA` |
+| 5 | 7 | `ZUBAT` |
+| 6 | 6 | `ONIX` |
+| 7 | 6 | `ONIX` |
+
+Water, `data/wild/johto_water.asm:12` `def_water_wildmons UNION_CAVE_1F`, rate
+`2 percent`: `15 WOOPER`, `20 QUAGSIRE`, `15 QUAGSIRE`.
+
+Fishing group is `FISHGROUP_LAKE` (header row).
+
+### MAP_UNION_CAVE_B1F
+
+- Script: `maps/UnionCaveB1F.asm`
+- Blocks: `maps/UnionCaveB1F.blk`
+- Header: `data/maps/maps.asm:108` -> `map UnionCaveB1F, TILESET_CAVE, CAVE, LANDMARK_UNION_CAVE, MUSIC_UNION_CAVE, TRUE, PALETTE_NITE, FISHGROUP_LAKE`
+- Dimensions: `constants/map_constants.asm:95` -> `map_const UNION_CAVE_B1F, 10, 18`
+- Attributes: `data/maps/attributes.asm:427` -> `map_attributes UnionCaveB1F, UNION_CAVE_B1F, $09`
+- Connections: none
+- Symbols: `44:5415 UnionCaveB1F_MapScripts`, `44:56df UnionCaveB1F_MapEvents` (`pokegold.sym`)
+
+**Warps** (`def_warp_events`)
+
+| idx | x | y | destination map | dest warp |
+|---|---|---|---|---|
+| 1 | 3 | 3 | `RUINS_OF_ALPH_OUTSIDE` | 7 |
+| 2 | 3 | 11 | `RUINS_OF_ALPH_OUTSIDE` | 8 |
+| 3 | 7 | 19 | `UNION_CAVE_1F` | 1 |
+| 4 | 3 | 33 | `UNION_CAVE_1F` | 2 |
+| 5 | 17 | 31 | `UNION_CAVE_B2F` | 1 |
+
+**Coord events** (`def_coord_events`)
+
+None.
+
+**BG events** (`def_bg_events`)
+
+None.
+
+**Object events** (`def_object_events`)
+
+| const | sprite | x | y | movement | type | script label | event flag |
+|---|---|---|---|---|---|---|---|
+| `UNIONCAVEB1F_POKEFAN_M1` | `SPRITE_POKEFAN_M` | 10 | 4 | `SPRITEMOVEDATA_SPINRANDOM_FAST` | `OBJECTTYPE_TRAINER`, sight 1 | `TrainerHikerPhillip` | -1 |
+| `UNIONCAVEB1F_POKEFAN_M2` | `SPRITE_POKEFAN_M` | 17 | 10 | `SPRITEMOVEDATA_STANDING_DOWN` | `OBJECTTYPE_TRAINER`, sight 3 | `TrainerHikerLeonard` | -1 |
+| `UNIONCAVEB1F_SUPER_NERD1` | `SPRITE_SUPER_NERD` | 5 | 32 | `SPRITEMOVEDATA_STANDING_LEFT` | `OBJECTTYPE_TRAINER`, sight 3 | `TrainerPokemaniacAndrew` | -1 |
+| `UNIONCAVEB1F_SUPER_NERD2` | `SPRITE_SUPER_NERD` | 17 | 30 | `SPRITEMOVEDATA_STANDING_LEFT` | `OBJECTTYPE_TRAINER`, sight 3 | `TrainerPokemaniacCalvin` | -1 |
+| `UNIONCAVEB1F_POKE_BALL1` | `SPRITE_POKE_BALL` | 2 | 16 | `SPRITEMOVEDATA_STILL` | `OBJECTTYPE_ITEMBALL` | `UnionCaveB1FTMSwift` | `EVENT_UNION_CAVE_B1F_TM_SWIFT` |
+| `UNIONCAVEB1F_BOULDER` | `SPRITE_BOULDER` | 7 | 10 | `SPRITEMOVEDATA_STRENGTH_BOULDER` | `OBJECTTYPE_SCRIPT` | `UnionCaveB1FBoulder` | -1 |
+| `UNIONCAVEB1F_POKE_BALL2` | `SPRITE_POKE_BALL` | 17 | 23 | `SPRITEMOVEDATA_STILL` | `OBJECTTYPE_ITEMBALL` | `UnionCaveB1FXDefend` | `EVENT_UNION_CAVE_B1F_X_DEFEND` |
+
+**Scripts of interest**
+
+- `UnionCaveB1F_MapScripts` - both `def_scene_scripts` and `def_callbacks` are
+  empty. Nothing on B1F is gated.
+- `TrainerPokemaniacAndrew` (`44:5417`) -
+  `trainer POKEMANIAC, ANDREW, EVENT_BEAT_POKEMANIAC_ANDREW, PokemaniacAndrewSeenText, PokemaniacAndrewBeatenText, 0, .Script`.
+  `.Script` is the boilerplate after-battle path:
+  `endifjustbattled / opentext / writetext PokemaniacAndrewAfterBattleText / waitbutton / closetext / end`.
+  No flags beyond the beaten flag, no items, no warps.
+- `TrainerPokemaniacCalvin` (`44:542b`) - identical shape with
+  `EVENT_BEAT_POKEMANIAC_CALVIN` and `PokemaniacCalvinAfterBattleText`
+  ("You demonstrated on me!" is `PokemaniacCalvinBeatenText`, matching the
+  walkthrough quote).
+- `UnionCaveB1FBoulder` - `jumpstd StrengthBoulderScript`. Not on the
+  walkthrough's path to Lapras (it sits at `7, 10`, up near the Ruins of Alph
+  ladders), but it is the one Strength-gated object on the floor.
+
+**Flags and events**
+
+| constant | defined in | read/written by | meaning for a bot |
+|---|---|---|---|
+| `EVENT_BEAT_POKEMANIAC_ANDREW` | `constants/event_flags.asm:751` | `TrainerPokemaniacAndrew` | set after the win; suppresses the eyesight trigger |
+| `EVENT_BEAT_POKEMANIAC_CALVIN` | `constants/event_flags.asm:752` | `TrainerPokemaniacCalvin` | same |
+| `EVENT_BEAT_HIKER_PHILLIP`, `EVENT_BEAT_HIKER_LEONARD` | `constants/event_flags.asm` | the two Hiker `trainer` rows | not on the Lapras path |
+| `EVENT_UNION_CAVE_B1F_TM_SWIFT` | `constants/event_flags.asm` | itemball object row | one-time TM_SWIFT |
+| `EVENT_UNION_CAVE_B1F_X_DEFEND` | `constants/event_flags.asm` | itemball object row | one-time X_DEFEND |
+
+**Items**
+
+| item | how obtained | source (label / bg_event / hidden) | one-time flag |
+|---|---|---|---|
+| `TM_SWIFT` | item ball at 2,16 | `UnionCaveB1FTMSwift` | `EVENT_UNION_CAVE_B1F_TM_SWIFT` |
+| `X_DEFEND` | item ball at 17,23 | `UnionCaveB1FXDefend` | `EVENT_UNION_CAVE_B1F_X_DEFEND` |
+
+Neither is mentioned by the walkthrough; both are on the way to the B2F ladder.
+
+**Trainers**
+
+| const | class | id | party (`data/trainers/parties.asm` label) | script label | rematch/phone |
+|---|---|---|---|---|---|
+| `POKEMANIAC`, `ANDREW` | `POKEMANIAC` (`$1e`, `constants/trainer_constants.asm:245`) | `ANDREW` (id 2) | `"ANDREW@", TRAINERTYPE_NORMAL` at `data/trainers/parties.asm:1086`: L24 `MAROWAK`, L24 `MAROWAK` | `TrainerPokemaniacAndrew` | no phone (map header phone flag `TRUE`) |
+| `POKEMANIAC`, `CALVIN` | `POKEMANIAC` | `CALVIN` (id 3) | `"CALVIN@", TRAINERTYPE_NORMAL` at `data/trainers/parties.asm:1092`: L26 `KANGASKHAN` | `TrainerPokemaniacCalvin` | no phone |
+| `HIKER`, `PHILLIP` | `HIKER` | `PHILLIP` | `"PHILLIP@"` | `TrainerHikerPhillip` | off-path |
+| `HIKER`, `LEONARD` | `HIKER` | `LEONARD` | `"LEONARD@"` | `TrainerHikerLeonard` | off-path |
+
+`TRAINERTYPE_NORMAL` means level+species only: no custom moves, no held items.
+
+Prize money: `POKEMANIAC` base reward is `db 15` (`data/trainers/attributes.asm:179`
+`; Pokemaniac`). `ComputeTrainerReward` (`engine/battle/read_trainer_party.asm:300`)
+computes `base * wCurPartyLevel` where the level is the **last** party row, and
+`WinTrainerBattle` (`engine/battle/core.asm:2292`) pays that out four times
+(`ld c, 4` at the `.okay` loop). So Andrew = 15*24*4 = **1440**, Calvin =
+15*26*4 = **1560** - both match the walkthrough exactly.
+
+**Wild encounters**
+
+Grass/cave, `data/wild/johto_grass.asm:499` `def_grass_wildmons UNION_CAVE_B1F`,
+rate `6 percent` morn/day/nite. Gold list (same in all three slots):
+
+| slot | level | species |
+|---|---|---|
+| 1 | 8 | `GEODUDE` |
+| 2 | 8 | `SANDSHREW` (Silver: `RATTATA`) |
+| 3 | 7 | `ZUBAT` |
+| 4 | 8 | `ONIX` |
+| 5 | 9 | `ZUBAT` |
+| 6 | 6 | `RATTATA` |
+| 7 | 6 | `RATTATA` |
+
+Water, `data/wild/johto_water.asm:19`, rate `2 percent`: `15 WOOPER`,
+`20 QUAGSIRE`, `15 QUAGSIRE`.
+
+### MAP_UNION_CAVE_B2F
+
+This is the section's real content.
+
+- Script: `maps/UnionCaveB2F.asm`
+- Blocks: `maps/UnionCaveB2F.blk` (`2b:466d UnionCaveB2F_Blocks`)
+- Header: `data/maps/maps.asm:109` -> `map UnionCaveB2F, TILESET_CAVE, CAVE, LANDMARK_UNION_CAVE, MUSIC_UNION_CAVE, TRUE, PALETTE_NITE, FISHGROUP_SHORE`
+  (note: **`FISHGROUP_SHORE` here, not `FISHGROUP_LAKE` like the two floors above**)
+- Dimensions: `constants/map_constants.asm:96` -> `map_const UNION_CAVE_B2F, 10, 18` (20x36 walk cells)
+- Attributes: `data/maps/attributes.asm:428` -> `map_attributes UnionCaveB2F, UNION_CAVE_B2F, $09`
+- Connections: none
+- Symbols: `44:5759 UnionCaveB2F_MapScripts`, `44:575e UnionCaveB2FLaprasCallback`, `44:5770 UnionCaveLapras`, `44:59cb UnionCaveB2F_MapEvents`, `25:595d UnionCaveB2F_MapAttributes`
+
+**Warps** (`def_warp_events`)
+
+| idx | x | y | destination map | dest warp |
+|---|---|---|---|---|
+| 1 | 5 | 3 | `UNION_CAVE_B1F` | 5 |
+
+One warp. There is no second exit: leaving is either back up this ladder, or
+Escape Rope / Dig (the walkthrough's suggestion).
+
+**Coord events** (`def_coord_events`)
+
+None - the block is empty. Nothing on B2F is a trip-wire; every event is an
+object you walk into the sight line of or press A on.
+
+**BG events** (`def_bg_events`)
+
+None.
+
+**Object events** (`def_object_events`)
+
+| const | sprite | x | y | movement | type | script label | event flag |
+|---|---|---|---|---|---|---|---|
+| `UNIONCAVEB2F_ROCKER` | `SPRITE_ROCKER` | 17 | 23 | `SPRITEMOVEDATA_STANDING_LEFT` | `OBJECTTYPE_TRAINER`, sight 5, `PAL_NPC_RED` | `TrainerCooltrainermNick` | -1 |
+| `UNIONCAVEB2F_COOLTRAINER_F1` | `SPRITE_COOLTRAINER_F` | 5 | 13 | `SPRITEMOVEDATA_SPINRANDOM_FAST` | `OBJECTTYPE_TRAINER`, sight 1, `PAL_NPC_RED` | `TrainerCooltrainerfGwen` | -1 |
+| `UNIONCAVEB2F_COOLTRAINER_F2` | `SPRITE_COOLTRAINER_F` | 3 | 28 | `SPRITEMOVEDATA_STANDING_DOWN` | `OBJECTTYPE_TRAINER`, sight 2, `PAL_NPC_RED` | `TrainerCooltrainerfEmma` | -1 |
+| `UNIONCAVEB2F_POKE_BALL1` | `SPRITE_POKE_BALL` | 16 | 2 | `SPRITEMOVEDATA_STILL` | `OBJECTTYPE_ITEMBALL` | `UnionCaveB2FElixer` | `EVENT_UNION_CAVE_B2F_ELIXER` |
+| `UNIONCAVEB2F_POKE_BALL2` | `SPRITE_POKE_BALL` | 12 | 19 | `SPRITEMOVEDATA_STILL` | `OBJECTTYPE_ITEMBALL` | `UnionCaveB2FHyperPotion` | `EVENT_UNION_CAVE_B2F_HYPER_POTION` |
+| `UNIONCAVEB2F_LAPRAS` | `SPRITE_SURF` | 11 | 31 | `SPRITEMOVEDATA_SWIM_WANDER`, radius x=1 y=1, `PAL_NPC_BLUE` | `OBJECTTYPE_SCRIPT` | `UnionCaveLapras` | `EVENT_UNION_CAVE_B2F_LAPRAS` |
+
+Notes a bot needs:
+
+- Lapras uses `SPRITE_SURF` (`constants/sprite_constants.asm:87`, id 53) - the
+  same overworld sprite the player rides. It is not a Lapras sprite.
+- `SPRITEMOVEDATA_SWIM_WANDER` with radius 1,1 means the object **drifts within
+  one cell of `11, 31`**. A driver must not hard-code an exact tile to face; it
+  should walk to the neighbourhood and press A at whichever adjacent water cell
+  the sprite is occupying.
+- Its event flag is `EVENT_UNION_CAVE_B2F_LAPRAS`. `CheckObjectFlag`
+  (`engine/overworld/map_objects_2.asm:31`) masks an object when the flag is
+  **set**, so "Lapras present" = flag clear.
+
+**Scripts of interest**
+
+`UnionCaveB2F_MapScripts` (`44:5759`)
+
+```
+	def_scene_scripts          ; empty
+	def_callbacks
+	callback MAPCALLBACK_OBJECTS, UnionCaveB2FLaprasCallback
+```
+
+`UnionCaveB2FLaprasCallback` (`44:575e`) - the whole Friday rule, six opcodes:
+
+```
+	checkflag ENGINE_UNION_CAVE_LAPRAS
+	iftrue .NoAppear
+	readvar VAR_WEEKDAY
+	ifequal FRIDAY, .Appear
+.NoAppear:
+	disappear UNIONCAVEB2F_LAPRAS
+	endcallback
+.Appear:
+	appear UNIONCAVEB2F_LAPRAS
+	endcallback
+```
+
+Control flow, spelled out:
+
+1. `checkflag ENGINE_UNION_CAVE_LAPRAS` - a **daily** engine flag
+   (`constants/engine_flags.asm:107`, in the `wDailyFlags2` block; bit
+   `DAILYFLAGS2_UNION_CAVE_LAPRAS_F` = 1, `constants/ram_constants.asm:315`).
+   Set means "already caught/fought it today" -> `.NoAppear`.
+2. `readvar VAR_WEEKDAY` (`constants/script_constants.asm:59`, id `$0b`) then
+   `ifequal FRIDAY` (`constants/ram_constants.asm:218`, `FRIDAY` = 5, Sunday-based).
+   Only Friday reaches `.Appear`.
+3. `appear` clears the object's event flag (`Script_appear`,
+   `engine/overworld/scripting.asm:879`, `ld b, 0 ; clear`); `disappear` sets it
+   (`Script_disappear`, `:887`, `ld b, 1 ; set`).
+
+Because the callback is `MAPCALLBACK_OBJECTS`, it re-runs on **every map load**
+of B2F (`engine/overworld/map_setup.asm:81` `farcall LoadObjectMasks` follows
+it). So a bot that walks out and back in on a non-Friday will find Lapras gone.
+
+`UnionCaveLapras` (`44:5770`) - the encounter itself:
+
+```
+	faceplayer
+	cry LAPRAS
+	loadwildmon LAPRAS, 20
+	startbattle
+	disappear UNIONCAVEB2F_LAPRAS
+	setflag ENGINE_UNION_CAVE_LAPRAS
+	reloadmapafterbattle
+	end
+```
+
+Load-bearing details:
+
+- `loadwildmon LAPRAS, 20` - a level **20 wild** Lapras, matching the
+  walkthrough. There is no `writevar VAR_BATTLETYPE` here, so unlike Ho-Oh /
+  Lugia / the Red Gyarados this is an **ordinary wild battle**: no forced item,
+  no forced shiny, no `BATTLETYPE_CANLOSE` mercy.
+- `disappear` and `setflag` run **unconditionally after the battle**, with no
+  `iffalse` / `checkflag` guard on the outcome. So Lapras is consumed for the
+  day whether you caught it, KO'd it, ran, or blacked out mid-battle. That is
+  exactly why the walkthrough says to save first - a soft reset is the only
+  recovery.
+- `setflag ENGINE_UNION_CAVE_LAPRAS` is the daily flag, not a permanent event.
+  `CheckDailyResetTimer` (`engine/overworld/time.asm:88`) zeroes `wDailyFlags1`
+  and `wDailyFlags2` whole once a day has elapsed, so it comes back next Friday.
+
+`TrainerCooltrainermNick` (`44:577f`), `TrainerCooltrainerfGwen` (`44:5793`),
+`TrainerCooltrainerfEmma` (`44:57a7`) - all three are the plain
+`trainer <class>, <id>, EVENT_BEAT_*, <seen>, <beaten>, 0, .Script` shape with
+an `endifjustbattled / opentext / writetext ...AfterBattleText / waitbutton /
+closetext / end` follow-up. No items, no warps, no flags beyond their own
+`EVENT_BEAT_*`.
+
+`CooltrainerfEmmaAfterBattleText` is the in-map hint for the whole section:
+*"Just once a week, a #MON comes to the water's edge. / I wanted to see that
+#MON..."*
+
+`UnionCaveB2FElixer` = `itemball ELIXER`; `UnionCaveB2FHyperPotion` =
+`itemball HYPER_POTION` (`macros/scripts/maps.asm:155`, two raw bytes
+`db item, quantity`, not bytecode).
+
+**Flags and events**
+
+| constant | defined in | read/written by | meaning for a bot |
+|---|---|---|---|
+| `ENGINE_UNION_CAVE_LAPRAS` | `constants/engine_flags.asm:107` (backed by `data/events/engine_flags.asm:117` -> `wDailyFlags2` bit `DAILYFLAGS2_UNION_CAVE_LAPRAS_F`) | read by `UnionCaveB2FLaprasCallback`, set by `UnionCaveLapras` | "Lapras already used up today". Cleared wholesale by `CheckDailyResetTimer` (`engine/overworld/time.asm:88-97`) |
+| `EVENT_UNION_CAVE_B2F_LAPRAS` | `constants/event_flags.asm:1282` | written by the callback's `appear`/`disappear` | object visibility mask. **Clear = visible** (`engine/overworld/map_objects_2.asm:31` `CheckObjectFlag`) |
+| `VAR_WEEKDAY` | `constants/script_constants.asm:59` (`$0b`) | `readvar` in the callback | `wCurDay`, 0 = `SUNDAY` .. 6 = `SATURDAY`; `FRIDAY` = 5 (`constants/ram_constants.asm:218`) |
+| `EVENT_BEAT_COOLTRAINERM_NICK` | `constants/event_flags.asm:857` | `TrainerCooltrainermNick` | beaten flag |
+| `EVENT_BEAT_COOLTRAINERF_GWEN` | `constants/event_flags.asm:877` | `TrainerCooltrainerfGwen` | beaten flag |
+| `EVENT_BEAT_COOLTRAINERF_EMMA` | `constants/event_flags.asm:891` | `TrainerCooltrainerfEmma` | beaten flag |
+| `EVENT_UNION_CAVE_B2F_ELIXER` | `constants/event_flags.asm:1025` | itemball object row | one-time |
+| `EVENT_UNION_CAVE_B2F_HYPER_POTION` | `constants/event_flags.asm:1026` | itemball object row | one-time |
+
+There are no `SCENE_*` values on this map: `def_scene_scripts` is empty, so
+`wMapScene` is never consulted here.
+
+**Items**
+
+| item | how obtained | source (label / bg_event / hidden) | one-time flag |
+|---|---|---|---|
+| `ELIXER` | item ball at 16,2 | `UnionCaveB2FElixer` (`itemball ELIXER`) | `EVENT_UNION_CAVE_B2F_ELIXER` |
+| `HYPER_POTION` | item ball at 12,19 | `UnionCaveB2FHyperPotion` (`itemball HYPER_POTION`) | `EVENT_UNION_CAVE_B2F_HYPER_POTION` |
+
+The walkthrough names only the Hyper Potion ("Land on the right side to grab a
+Hyper Potion"). The Elixer at `16, 2` sits near the arrival ladder at `5, 3` and
+is never mentioned - free pickup for a bot on the way in.
+
+**Trainers**
+
+| const | class | id | party (`data/trainers/parties.asm` label) | script label | rematch/phone |
+|---|---|---|---|---|---|
+| `COOLTRAINERM`, `NICK` | `COOLTRAINERM` (`$1b`, `constants/trainer_constants.asm:184`) | `NICK` (id 1) | `"NICK@", TRAINERTYPE_MOVES` at `data/trainers/parties.asm:742` | `TrainerCooltrainermNick` | no phone (map phone flag `TRUE`) |
+| `COOLTRAINERF`, `GWEN` | `COOLTRAINERF` (`$1c`, `:205`) | `GWEN` (id 1) | `"GWEN@", TRAINERTYPE_NORMAL` at `:867` | `TrainerCooltrainerfGwen` | no phone |
+| `COOLTRAINERF`, `EMMA` | `COOLTRAINERF` | `EMMA` (id 15) | `"EMMA@", TRAINERTYPE_NORMAL` at `:954` | `TrainerCooltrainerfEmma` | no phone |
+
+Parties verbatim:
+
+`NICK` (`TRAINERTYPE_MOVES` - custom movesets, no items):
+
+| # | level | species | moves |
+|---|---|---|---|
+| 1 | 26 | `CHARMANDER` | `EMBER`, `SMOKESCREEN`, `RAGE`, `SCARY_FACE` |
+| 2 | 26 | `SQUIRTLE` | `WITHDRAW`, `WATER_GUN`, `BITE`, `CURSE` |
+| 3 | 26 | `BULBASAUR` | `LEECH_SEED`, `POISONPOWDER`, `SLEEP_POWDER`, `RAZOR_LEAF` |
+
+`GWEN` (`TRAINERTYPE_NORMAL`):
+
+| # | level | species |
+|---|---|---|
+| 1 | 26 | `EEVEE` |
+| 2 | 22 | `FLAREON` |
+| 3 | 22 | `VAPOREON` |
+| 4 | 22 | `JOLTEON` |
+
+`EMMA` (`TRAINERTYPE_NORMAL`): L28 `POLIWHIRL`, single mon.
+
+Prize money (`base * last-party-level * 4`, see the B1F note): `COOLTRAINERM`
+and `COOLTRAINERF` both have `db 12 ; base reward`
+(`data/trainers/attributes.asm:161` `; Cooltrainerm`, `:167` `; Cooltrainerf`).
+Nick = 12*26*4 = **1248**, Gwen = 12*22*4 = **1056** (last row is the L22
+Jolteon), Emma = 12*28*4 = **1344**. All three match the walkthrough.
+
+AI: both Cooltrainer classes carry the full
+`AI_BASIC | AI_SETUP | AI_SMART | AI_AGGRESSIVE | AI_CAUTIOUS | AI_STATUS | AI_RISKY`
+set and `SWITCH_SOMETIMES`; Pokemaniac is the weaker
+`AI_BASIC | AI_SETUP | AI_OFFENSIVE | AI_AGGRESSIVE | AI_STATUS`. None of the
+five hold items (`db NO_ITEM, NO_ITEM`).
+
+**Wild encounters**
+
+Grass/cave, `data/wild/johto_grass.asm:554` `def_grass_wildmons UNION_CAVE_B2F`,
+rate `4 percent`. This table is **not** split by version, and all three
+time-of-day slots are identical:
+
+| slot | level | species |
+|---|---|---|
+| 1 | 22 | `ZUBAT` |
+| 2 | 22 | `RATICATE` |
+| 3 | 22 | `GOLBAT` |
+| 4 | 21 | `GEODUDE` |
+| 5 | 20 | `RATTATA` |
+| 6 | 23 | `ONIX` |
+| 7 | 23 | `ONIX` |
+
+Water (the surf legs the walkthrough spends most of its time on),
+`data/wild/johto_water.asm:26` `def_water_wildmons UNION_CAVE_B2F`, rate
+`4 percent` (double the 1F/B1F water rate):
+
+| slot | level | species |
+|---|---|---|
+| 1 | 15 | `TENTACOOL` |
+| 2 | 20 | `QUAGSIRE` |
+| 3 | 20 | `TENTACRUEL` |
+
+Fishing group is `FISHGROUP_SHORE` (`data/maps/maps.asm:109`). No headbutt or
+rock-smash tables apply - it is a cave with no trees.
+
+The walkthrough's Max Repel advice: `REPEL_STEPS` in the port mirrors
+`RepelEffect / SuperRepelEffect / MaxRepelEffect`; MAX_REPEL is 250 steps. With
+the B2F encounters capped at level 23 and the lead mon typically above that,
+Repel suppresses essentially all of the grass rolls.
+
+## 3. Blockers and gates
+
+| Gate | Enforced by (file:label) | Requirement | Unlock condition |
+|---|---|---|---|
+| Cannot cross any of the water on 1F / B1F / B2F | `engine/events/overworld.asm:322` `SurfFunction.TrySurf` (`ld de, ENGINE_FOGBADGE / call CheckBadge / jr c, .nofogbadge`), and the walk-into-water path `TrySurfOW` at `:469` | **Fog Badge** plus a party mon that knows `SURF` | beat Morty in Ecruteak Gym (section 07) |
+| Lapras object is absent 6 days out of 7 | `maps/UnionCaveB2F.asm:15` `UnionCaveB2FLaprasCallback` -> `readvar VAR_WEEKDAY / ifequal FRIDAY` | in-game weekday must equal `FRIDAY` (`constants/ram_constants.asm:218`, value 5) | set the GB clock / wait for Friday. Re-checked on every B2F map load (`MAPCALLBACK_OBJECTS`) |
+| Lapras is absent again after one encounter | same callback, first two opcodes: `checkflag ENGINE_UNION_CAVE_LAPRAS / iftrue .NoAppear`; the flag is set by `UnionCaveLapras` | flag must be clear | `CheckDailyResetTimer` (`engine/overworld/time.asm:88`) zeroes `wDailyFlags1`+`wDailyFlags2` once a real day has passed |
+| Lapras is consumed even on a failed attempt | `UnionCaveLapras`: `startbattle` is followed unconditionally by `disappear` + `setflag` - no `iffalse` on `wBattleResult` | none - this is the failure mode, not a gate | save before pressing A; soft-reset on a bad outcome |
+| Only one way out of B2F | `maps/UnionCaveB2F.asm` `def_warp_events` has exactly one row (`5, 3 -> UNION_CAVE_B1F, 5`) | - | Escape Rope / Dig short-circuits the return walk (B2F's tileset is `TILESET_CAVE`) |
+| Boulder at B1F `7, 10` | `UnionCaveB1FBoulder` -> `jumpstd StrengthBoulderScript` | Strength / Plain Badge | not on the Lapras path; noted for completeness |
+
+Nothing in this section checks a badge count, a key item, or an `EVENT_*`
+story flag. The only two real gates are **Surf** and **Friday**.
+
+## 4. Bot checklist
+
+Preconditions for the whole section: Fog Badge, a party mon with `SURF`, the
+in-game weekday equal to `FRIDAY`, `ENGINE_UNION_CAVE_LAPRAS` clear, several
+Ultra Balls, a status move (Sleep/Paralysis) and a **save written immediately
+before the Lapras press**.
+
+| # | Map | Target | Input intent | Precondition | Postcondition |
+|---|---|---|---|---|---|
+| 1 | `MAP_ROUTE_32` | warp at `6, 79` | walk onto the warp | on Route 32 | now in `MAP_UNION_CAVE_1F` at `17, 3` (warp 4) |
+| 2 | `MAP_UNION_CAVE_1F` | - | use `MAX_REPEL` from the pack | have one | 250 steps of encounter suppression |
+| 3 | `MAP_UNION_CAVE_1F` | avoid sight lines of `UNIONCAVE1F_POKEFAN_M2` (`15, 8`, sight 3, facing left) and `UNIONCAVE1F_FISHER2` (`15, 15`, sight 2, spinner) | walk south-west | - | `EVENT_BEAT_*` untouched if avoided; the spinner is not reliably avoidable, budget for the battle |
+| 4 | `MAP_UNION_CAVE_1F` | south-west water | press A facing water, or walk into it (`TrySurfOW`) | Fog Badge + `SURF` | `wPlayerState = PLAYER_SURF` |
+| 5 | `MAP_UNION_CAVE_1F` | warp 2 at `3, 33` | step onto it | - | now in `MAP_UNION_CAVE_B1F` at `3, 33` (warp 4) |
+| 6 | `MAP_UNION_CAVE_B1F` | `UNIONCAVEB1F_SUPER_NERD1` at `5, 32` (facing left, sight 3) | walk into the sight line / talk | - | battle Pokemaniac Andrew (2x L24 Marowak); sets `EVENT_BEAT_POKEMANIAC_ANDREW`, +1440 |
+| 7 | `MAP_UNION_CAVE_B1F` | surf east along the y~30 water | walk east on water | surfing | reach the eastern shelf |
+| 8 | `MAP_UNION_CAVE_B1F` | `UNIONCAVEB1F_SUPER_NERD2` at `17, 30` (facing left, sight 3) | walk into the sight line | - | battle Pokemaniac Calvin (L26 Kangaskhan); sets `EVENT_BEAT_POKEMANIAC_CALVIN`, +1560 |
+| 9 | `MAP_UNION_CAVE_B1F` | optional item ball `17, 23` | press A | `EVENT_UNION_CAVE_B1F_X_DEFEND` clear | `X_DEFEND` in bag, flag set |
+| 10 | `MAP_UNION_CAVE_B1F` | warp 5 at `17, 31` | step onto it | - | now in `MAP_UNION_CAVE_B2F` at `5, 3`; `MAPCALLBACK_OBJECTS` runs `UnionCaveB2FLaprasCallback` |
+| 11 | `MAP_UNION_CAVE_B2F` | **assert** `UNIONCAVEB2F_LAPRAS` is present | read the object list | weekday == FRIDAY and `ENGINE_UNION_CAVE_LAPRAS` clear | if absent, abort the run - nothing later will fix it |
+| 12 | `MAP_UNION_CAVE_B2F` | item ball `16, 2` | press A | `EVENT_UNION_CAVE_B2F_ELIXER` clear | `ELIXER` in bag (walkthrough omits this one) |
+| 13 | `MAP_UNION_CAVE_B2F` | surf south from the entrance shelf | walk south on water | surfing | approach the y~19-23 shelves |
+| 14 | `MAP_UNION_CAVE_B2F` | item ball `12, 19` (right-hand shore) | land, press A | `EVENT_UNION_CAVE_B2F_HYPER_POTION` clear | `HYPER_POTION` in bag |
+| 15 | `MAP_UNION_CAVE_B2F` | `UNIONCAVEB2F_ROCKER` at `17, 23` (facing left, sight 5 - the longest on the floor) | walk into the sight line | - | battle Cooltrainer Nick (L26 Charmander/Squirtle/Bulbasaur, custom moves); sets `EVENT_BEAT_COOLTRAINERM_NICK`, +1248 |
+| 16 | `MAP_UNION_CAVE_B2F` | cross to the left shore, head north to `UNIONCAVEB2F_COOLTRAINER_F1` at `5, 13` (spinner, sight 1) | walk adjacent | - | battle Cooltrainer Gwen (L26 Eevee, L22 Flareon/Vaporeon/Jolteon); sets `EVENT_BEAT_COOLTRAINERF_GWEN`, +1056 |
+| 17 | `MAP_UNION_CAVE_B2F` | walk the left path south to `UNIONCAVEB2F_COOLTRAINER_F2` at `3, 28` (facing down, sight 2) | walk into the sight line | - | battle Cooltrainer Emma (L28 Poliwhirl); sets `EVENT_BEAT_COOLTRAINERF_EMMA`, +1344 |
+| 18 | `MAP_UNION_CAVE_B2F` | **save** | open menu -> SAVE | Lapras still present | recoverable checkpoint |
+| 19 | `MAP_UNION_CAVE_B2F` | surf east/south-east from `3, 28` toward `11, 31` | walk on water | surfing | the Lapras object drifts within +/-1 cell of `11, 31` (`SWIM_WANDER`, radius 1,1) - re-scan its live position each step |
+| 20 | `MAP_UNION_CAVE_B2F` | press A facing `UNIONCAVEB2F_LAPRAS` | talk | object present | `UnionCaveLapras` runs: `cry LAPRAS`, `loadwildmon LAPRAS, 20`, `startbattle` |
+| 21 | battle | L20 wild Lapras | inflict sleep/paralysis, chip to yellow/red, throw `ULTRA_BALL`s | - | on any exit: `disappear` + `setflag ENGINE_UNION_CAVE_LAPRAS`, then `reloadmapafterbattle` |
+| 22 | - | verify Lapras in party/box | read party | - | if not caught, **reload the step-18 save**; do not walk out and back in, the callback will not re-place it |
+| 23 | `MAP_UNION_CAVE_B2F` | use `ESCAPE_ROPE` | pack -> use | in a cave tileset | back at the last Pokemon Center door |
+
+Sight-line arithmetic for steps 6/8/15/16/17: `Trainers.sees` in the port
+(`src/world/gen2/Trainers.lua:98`) is the transcription of `home/trainers.asm` -
+the NPC must be facing the player's direction and the Chebyshev-free straight
+distance must be `<= sight`.
+
+## 5. Port coverage
+
+| Beat | Port file | Status |
+|---|---|---|
+| Union Cave 1F/B1F/B2F map data (headers, blocks, warps, objects) | `src/import/RomExtractorGen2.lua` (generic map/manifest extraction; per-map entries land in the private `data/generated/` cache) | implemented - data-driven, no per-map code |
+| `MAPCALLBACK_OBJECTS` dispatch on map load | `src/world/gen2/World.lua:5700` (`self:runMapCallback("MAPCALLBACK_OBJECTS")`, deliberately *before* the sprite rebuild) | implemented |
+| `readvar VAR_WEEKDAY` | `src/world/gen2/World.lua:101` (`VAR_WEEKDAY = 0x0b`) and `:1222` (`if varId == VAR_WEEKDAY then return self:weekday() end`) | implemented |
+| `checkflag` / `setflag` on `ENGINE_*` | `src/script/gen2/Vm.lua:195` / `:208` | implemented |
+| `ENGINE_UNION_CAVE_LAPRAS` as a daily flag | `src/core/gen2/Apricorns.lua:84` (`{ id = 88, name = "ENGINE_UNION_CAVE_LAPRAS" }` in the wDailyFlags1/2 id list) and `:344` (`save.dailyFlags = {}` on the daily wipe) | implemented |
+| `appear` / `disappear` object masking | `src/script/gen2/Opcodes.lua:115-116`, consumed by the World object rebuild | implemented |
+| `cry` | `src/script/gen2/Vm.lua:621` | implemented |
+| `loadwildmon` + `startbattle` + `reloadmapafterbattle` (the whole static-encounter shape) | `src/script/gen2/Vm.lua:836`, `:817`, `:886` | implemented |
+| Wild catch rate / Ultra Ball / status bonus | `src/battle/gen2/Catching.lua` (transcribes `PokeBallEffect`, including the two cart bugs) | implemented |
+| Water encounter tables while surfing | `src/world/gen2/FieldMoves.lua:175` ("standing in a cave rolls the grass list; surfing rolls the water" ...) + `src/battle/gen2/Encounter.lua` | implemented |
+| Surf gate on `ENGINE_FOGBADGE` | `src/world/gen2/FieldMoves.lua:106` (`SURF = "FOG"`) and `FieldMoves.surfFromMenu` at `:481` | implemented |
+| Trainer eyesight approach + battle | `src/world/gen2/Trainers.lua:98` (`Trainers.sees`), `src/world/gen2/World.lua:5212` / `:5227` / `:5242` | implemented |
+| Trainer prize money (base x level x 4, Mom's split) | `src/battle/gen2/Prize.lua:82` (`Prize.reward`), `:92` (`Prize.rewardLevel`) | implemented - and it already documents the `ld c, 4` that makes the walkthrough's figures right |
+| Repel step counting (the Max Repel advice) | `src/world/gen2/World.lua:317` (`REPEL_STEPS = { REPEL = 100, SUPER_REPEL = 200, MAX_REPEL = 250 }`), `:3366` | implemented |
+| **Item ball pickup** (`OBJECTTYPE_ITEMBALL`, i.e. the B2F Elixer / Hyper Potion and every ball on 1F/B1F) | extractor stores the item at `src/import/RomExtractorGen2.lua:2969` (`obj.itemball = readItemBall(...)`) and deliberately assigns **no** `scriptKey`; `World:talk` only dispatches on `npc.def.scriptKey` (`src/world/gen2/World.lua:5276`) | **missing** - no consumer of `obj.itemball` exists anywhere under `src/`. Pressing A on a Poke Ball object currently does nothing |
+| Escape Rope from a cave | `src/ui/PartyMenu.lua:634` is the Gen 1 DIG/ESCAPE_ROPE path; no Gen 2 equivalent found under `src/core/gen2/` or `src/world/gen2/` | **unverified / likely missing for Gen 2** - a driver should warp out manually |
+| A driver exercising the weekday-gated `MAPCALLBACK_OBJECTS` shape | `tests/drivers/gold_map_callbacks.lua:117-156` covers the same pattern on Route 29 (Tuscany, Tuesday) | implemented for the pattern, **not** for Union Cave B2F specifically - no `tests/drivers/gold_*` driver mentions Union Cave or Lapras |
+
+Honest summary: everything the Lapras encounter itself needs is in place
+(callback dispatch, weekday var, daily flags, `loadwildmon`/`startbattle`,
+catching). The two gaps that would bite a bot on this route are **item balls
+are not pickable** and **no Gen 2 Escape Rope**, neither of which blocks Lapras.
+
+## 6. Unresolved / verify by hand
+
+- **"Lapras only appears on Friday" vs. the 1F NPC hints.** The code checks
+  exactly `FRIDAY` (`UnionCaveB2FLaprasCallback`). But
+  `FirebreatherBillAfterBattleText` on 1F says *"On weekends, you can hear
+  strange roars from deep in the cave"* while `PokemaniacLarryAfterBattleText`
+  says *"Every Friday"*. Larry is right, Bill's line is flavour that contradicts
+  the callback. The walkthrough follows Larry and is correct.
+- **"once you've gotten HM Surf".** The asm imposes no HM/badge check on the
+  Lapras callback or on `UnionCaveLapras`; Surf is a *reachability* requirement
+  (B2F's Lapras sits at `11, 31` surrounded by water and the approach legs on
+  1F/B1F cross water), enforced only by `SurfFunction.TrySurf`'s
+  `ENGINE_FOGBADGE` check. The walkthrough's phrasing implies a scripted gate
+  that does not exist.
+- **EXP figures.** The walkthrough quotes per-mon EXP (637 for a L24 Marowak,
+  975 for a L26 Kangaskhan, 355/511/924/928/933/786, and two "?" entries). EXP
+  is computed at runtime from base EXP x level, not stored per trainer, so none
+  of these could be pinned to a table row. They are plausible but unverified
+  here; `data/pokemon/base_stats/*.asm` would be the place to check.
+- **Party ordering.** The walkthrough lists Nick as Charmander / Bulbasaur /
+  Squirtle and Gwen as Eevee / Vaporeon / Jolteon / Flareon. `parties.asm` has
+  Nick as Charmander / **Squirtle** / **Bulbasaur** (`:742`) and Gwen as Eevee /
+  **Flareon** / **Vaporeon** / **Jolteon** (`:867`). The sets match; the order
+  does not. A bot planning lead matchups should use the asm order (it is also
+  what decides the prize level: Gwen's last row is Jolteon L22).
+- **"Head almost all the way through till you see the guy on the cliff still
+  spinning around, which is the third trainer that you spot."** Read against the
+  1F object table this is `UNIONCAVE1F_FISHER2` (Firebreather Bill,
+  `15, 15`, `SPRITEMOVEDATA_SPINRANDOM_FAST`), with Hiker Daniel (`4, 4`) and
+  Hiker Russell (`15, 8`) as the first two. That reading is an inference from
+  coordinates and movement data, not something the asm states; the exact walking
+  order depends on the `.blk` layout, which was not decoded here.
+- **Which 1F ladder the walkthrough means.** "Down and to the left is a lake.
+  Surf past it and head down the ladder" is read as 1F warp 2 (`3, 33` ->
+  `UNION_CAVE_B1F` warp 4 at `3, 33`), because Andrew stands at B1F `5, 32`,
+  immediately beside that arrival point. 1F warp 1 (`5, 19` -> B1F warp 3 at
+  `7, 19`) would land nowhere near him. Verify against the block layout if a
+  driver's pathing disagrees.
+- **B2F "right side" / "left side" landings.** The prose distinguishes a right
+  and a left shore; the object coordinates (`12, 19` Hyper Potion and `17, 23`
+  Nick on the right, `5, 13` Gwen and `3, 28` Emma on the left) are consistent
+  with that, but the actual water/land split comes from `UnionCaveB2F.blk`,
+  which was not decoded.
+- **Elixer at B2F `16, 2`.** Present in the asm, absent from the walkthrough.
+  Not a contradiction, just an omission worth picking up.