feat(mods): expose contextual field items

src/mods/Gen2Compat.lua

@@ -737,7 +737,8 @@ COVERAGE["src.pokemon.Boxes"] = {
 COVERAGE["src.world.WorldAPI"] = {
   kind = "alias", target = "src.world.gen2.WorldAPI",
   backed = "new __index overworld current mapOverview warpTo toggleObject replaceBlock "
-    .. "spawnNpc removeNpc npc queueScript invalidateMap",
+    .. "spawnNpc removeNpc npc queueScript invalidateMap "
+    .. "availableFieldActions useFieldAction",
   warned = "setFlag getFlag",
   absent = "",
   notes = {

src/world/OverworldController.lua

@@ -763,6 +763,27 @@ function OverworldState:bikeAllowed(mapId)
   return false
 end
 
+-- Field-item entry points keep presentation and state transitions in the
+-- owning world instead of asking a supported facade to reproduce either one.
+function OverworldState:useBicycle()
+  local name = Game.save.player.name
+  if Game.save.onBike then
+    if Game.save.forcedBike then return false end
+    Game.save.onBike = false
+    require("src.core.Music").playMap(Game.data, self.map.id, false)
+    Game.stack:push(TextBox.new(Game,
+      Strings("%s got off\nthe BICYCLE.", name)))
+  elseif self:bikeAllowed(self.map.id) and not self.player.surfing then
+    Game.save.onBike = true
+    require("src.core.Music").playMap(Game.data, self.map.id, true)
+    Game.stack:push(TextBox.new(Game,
+      Strings("%s got on\nthe BICYCLE!", name)))
+  else
+    return false
+  end
+  return true
+end
+
 -- The battle transition's dungeon wipe uses the explicit map lists in
 -- data/maps/dungeon_maps.asm (field.dungeonTransitionMaps): singles plus
 -- inclusive map-id ranges -- faithful to the original's omissions
@@ -1726,6 +1747,12 @@ function OverworldState:goFishing(rod)
   end))
 end
 
+function OverworldState:useFishingRod(rod)
+  if self.player.surfing or not self:facingIsShoreOrWater() then return false end
+  self:goFishing(rod)
+  return true
+end
+
 -- Fly to a visited town (called from the party menu).
 function OverworldState:flyTo(mapId)
   local spot = Game.data.field.flyWarps[mapId]

src/world/WorldAPI.lua

@@ -15,6 +15,7 @@ local WorldAPI = {}
 WorldAPI.__index = WorldAPI
 
 local NO_OVERWORLD = "no overworld"
+local RODS = { "OLD_ROD", "GOOD_ROD", "SUPER_ROD" }
 
 local function acceptsMenuInput(game, ow)
   local stack = game and game.stack
@@ -86,6 +87,60 @@ function WorldAPI:reorderParty(fromSlot, toSlot)
   return true
 end
 
+-- Contextual field-item shortcuts. Only actions that can start immediately
+-- are listed; callers receive copied labels and never inspect world internals.
+function WorldAPI:availableFieldActions()
+  local game, ow, out = self.game, self:overworld(), {}
+  if not (game and game.save and ow and ow.map and ow.player)
+      or not acceptsMenuInput(game, ow) then return out end
+  local save, inventory = game.save, game.save.inventory or {}
+  local items = game.data and game.data.items or {}
+
+  if (inventory.BICYCLE or 0) > 0 and not ow.player.surfing
+      and not (save.onBike and save.forcedBike)
+      and (save.onBike or ow:bikeAllowed(ow.map.id)) then
+    out[#out + 1] = { id = "bicycle",
+      label = save.onBike and "BIKE OFF" or "BICYCLE" }
+  end
+
+  if not ow.player.surfing and ow:facingIsShoreOrWater() then
+    local rods = {}
+    for _, id in ipairs(RODS) do
+      if (inventory[id] or 0) > 0 then
+        local def = items[id]
+        rods[#rods + 1] = { id = id, label = def and def.name or id }
+      end
+    end
+    if #rods > 0 then
+      out[#out + 1] = { id = "fish", label = "FISH", rods = rods }
+    end
+  end
+  return out
+end
+
+function WorldAPI:useFieldAction(id, opts)
+  local game, ow = self.game, self:overworld()
+  if not ow then return nil, NO_OVERWORLD end
+  if not acceptsMenuInput(game, ow) then return nil, "world is busy" end
+  local found
+  for _, action in ipairs(self:availableFieldActions()) do
+    if action.id == id then found = action break end
+  end
+  if not found then return nil, "field action unavailable" end
+
+  if id == "bicycle" then
+    if ow:useBicycle() then return true end
+  elseif id == "fish" then
+    local rod = opts and opts.rod
+    if not rod and #found.rods == 1 then rod = found.rods[1].id end
+    for _, choice in ipairs(found.rods) do
+      if choice.id == rod and ow:useFishingRod(rod) then return true end
+    end
+    return nil, "fishing rod unavailable"
+  end
+  return nil, "field action unavailable"
+end
+
 -- A compact, read-only view of the active map for minimaps and companion UIs.
 -- `rows` describes collision terrain; optional `tileRows` reduces each real
 -- 8x8 map tile to its average Game Boy shade ("0" lightest, "3" darkest).

src/world/gen2/WorldAPI.lua

@@ -27,11 +27,15 @@ local Movement = require("src.script.gen2.Movement")
 local Runtime = require("src.mods.Runtime")
 local HiddenItems = require("src.world.gen2.HiddenItems")
 local MapOverview = require("src.world.MapOverview")
+local Bike = require("src.world.gen2.Bike")
+local FieldMoves = require("src.world.gen2.FieldMoves")
+local Permissions = require("src.world.gen2.Permissions")
 
 local WorldAPI = {}
 WorldAPI.__index = WorldAPI
 
 local NO_OVERWORLD = "no overworld"
+local RODS = { "OLD_ROD", "GOOD_ROD", "SUPER_ROD" }
 
 function WorldAPI.new(game, modId)
   return setmetatable({ game = game, modId = modId }, WorldAPI)
@@ -52,6 +56,77 @@ function WorldAPI:current()
            facing = p and p.facing }
 end
 
+local function itemLabel(game, id)
+  local def = game and game.data and game.data.items
+    and game.data.items[id]
+  return (def and def.name) or id
+end
+
+-- The same field-item contract as Gen 1, resolved through Gold's own bike,
+-- collision and fishing rules.
+function WorldAPI:availableFieldActions()
+  local world, game, out = self:overworld(), self.game, {}
+  if not (world and game and game.save and world.map and world.player)
+      or not world:acceptsMenuInput() then return out end
+  local inventory = game.save.inventory or {}
+
+  if (inventory.BICYCLE or 0) > 0 then
+    local bike = Bike.tryBike({
+      state = world.playerState,
+      environment = world.map.def and world.map.def.environment,
+      collision = world:playerCollision(),
+      alwaysOnBike = world:alwaysOnBike(),
+    })
+    if bike == "mount" or bike == "dismount" then
+      out[#out + 1] = { id = "bicycle",
+        label = bike == "dismount" and "BIKE OFF" or "BICYCLE" }
+    end
+  end
+
+  local context = world:fieldContext()
+  if not FieldMoves.isSurfing(world.playerState)
+      and Permissions.isWater(context.facingColl) then
+    local rods = {}
+    for _, id in ipairs(RODS) do
+      if (inventory[id] or 0) > 0 then
+        rods[#rods + 1] = { id = id, label = itemLabel(game, id) }
+      end
+    end
+    if #rods > 0 then
+      out[#out + 1] = { id = "fish", label = "FISH", rods = rods }
+    end
+  end
+  return out
+end
+
+function WorldAPI:useFieldAction(id, opts)
+  local world = self:overworld()
+  if not world then return nil, NO_OVERWORLD end
+  if not world:acceptsMenuInput() then return nil, "world is busy" end
+  local found
+  for _, action in ipairs(self:availableFieldActions()) do
+    if action.id == id then found = action break end
+  end
+  if not found then return nil, "field action unavailable" end
+
+  if id == "bicycle" then
+    local outcome = world:useFieldItem("BICYCLE")
+    if outcome and outcome ~= "nowhere" then return true end
+  elseif id == "fish" then
+    local rod = opts and opts.rod
+    if not rod and #found.rods == 1 then rod = found.rods[1].id end
+    for _, choice in ipairs(found.rods) do
+      if choice.id == rod then
+        local outcome = world:useFieldItem(rod)
+        if outcome and outcome ~= "nowhere" then return true end
+        break
+      end
+    end
+    return nil, "fishing rod unavailable"
+  end
+  return nil, "field action unavailable"
+end
+
 -- The same read-only minimap contract as Gen 1, with Gold's object/event
 -- visibility rules supplying the semantic markers.
 function WorldAPI:mapOverview()