feat: add pairKey, Alchemy.herb and Analytics.winRate

src/alchemy.lua

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+-- Herb-based potion brewing, layered on top of items.lua's existing potion
+-- catalog rather than inventing a second one: a cauldron turns two foraged
+-- herbs into the same potions rollItem already scatters as loot, so a
+-- brewed potion drinks, throws (throwing.lua) and identifies exactly like a
+-- found one. Recipes are fixed data, the same way crafting.lua's elemental
+-- riders are fixed - the uncertainty here is not "what does this pair do"
+-- but whether two ill-matched herbs curdle instead of brewing cleanly. See
+-- Game:brewAt for how a curdle is resolved against the brewer.
+
+local Items = require("items")
+
+local Alchemy = {}
+
+Alchemy.SUNPETAL = "sunpetal"
+Alchemy.BLOODROOT = "bloodroot"
+Alchemy.EMBERLEAF = "emberleaf"
+Alchemy.FROSTMOSS = "frostmoss"
+Alchemy.NIGHTCAP = "nightcap"
+Alchemy.MOONBELL = "moonbell"
+
+-- Fixed order so a given rng draw always names the same herb. New herbs
+-- append at the end (see builder.lua's own comment on Alchemy.order) so an
+-- existing seed's earlier picks never change which herb they name.
+Alchemy.order = {
+  Alchemy.BLOODROOT, Alchemy.EMBERLEAF, Alchemy.FROSTMOSS, Alchemy.NIGHTCAP, Alchemy.SUNPETAL,
+  Alchemy.MOONBELL,
+}
+
+Alchemy.names = {
+  [Alchemy.SUNPETAL] = "sunpetal",
+  [Alchemy.BLOODROOT] = "bloodroot",
+  [Alchemy.EMBERLEAF] = "emberleaf",
+  [Alchemy.FROSTMOSS] = "frostmoss",
+  [Alchemy.NIGHTCAP] = "nightcap",
+  [Alchemy.MOONBELL] = "moonbell",
+}
+
+local CURDLE = { curdle = true }
+
+-- Canonical order-independent key for a herb pair: the two herb keys sorted
+-- and joined, so brewing (A, B) and (B, A) always land on the same recipe.
+local function pairKey(a, b)
+  if a > b then a, b = b, a end
+  return a .. "+" .. b
+end
+Alchemy.pairKey = pairKey
+
+-- Same-herb pairs concentrate that herb's own aspect; cross pairs blend two
+-- aspects into a shared potion, except the pairings whose aspects outright
+-- oppose each other (light versus shade, fire versus frost, day versus
+-- dream), which curdle instead of brewing.
+Alchemy.recipes = {
+  [pairKey(Alchemy.SUNPETAL, Alchemy.SUNPETAL)] = { effect = "heal", power = 18 },
+  [pairKey(Alchemy.SUNPETAL, Alchemy.BLOODROOT)] = { effect = "heal", power = 10 },
+  [pairKey(Alchemy.SUNPETAL, Alchemy.EMBERLEAF)] = { effect = "haste" },
+  [pairKey(Alchemy.SUNPETAL, Alchemy.FROSTMOSS)] = { effect = "fortify" },
+  [pairKey(Alchemy.SUNPETAL, Alchemy.NIGHTCAP)] = CURDLE,
+  [pairKey(Alchemy.BLOODROOT, Alchemy.BLOODROOT)] = { effect = "strength" },
+  [pairKey(Alchemy.BLOODROOT, Alchemy.EMBERLEAF)] = { effect = "strength" },
+  [pairKey(Alchemy.BLOODROOT, Alchemy.FROSTMOSS)] = { effect = "fortify" },
+  [pairKey(Alchemy.BLOODROOT, Alchemy.NIGHTCAP)] = { effect = "poison", power = 4 },
+  [pairKey(Alchemy.EMBERLEAF, Alchemy.EMBERLEAF)] = { effect = "haste" },
+  [pairKey(Alchemy.EMBERLEAF, Alchemy.FROSTMOSS)] = CURDLE,
+  [pairKey(Alchemy.EMBERLEAF, Alchemy.NIGHTCAP)] = { effect = "poison", power = 5 },
+  [pairKey(Alchemy.FROSTMOSS, Alchemy.FROSTMOSS)] = { effect = "fortify" },
+  [pairKey(Alchemy.FROSTMOSS, Alchemy.NIGHTCAP)] = { effect = "poison", power = 5 },
+  [pairKey(Alchemy.NIGHTCAP, Alchemy.NIGHTCAP)] = { effect = "poison", power = 7 },
+  -- Moonbell's own aspect is dream-fog, so concentrating it addles the
+  -- brewer's own mind rather than anyone else's - the same "own aspect
+  -- turned inward" shape as every other same-herb pair above. Sunlight is
+  -- the one aspect it outright opposes (wakeful day versus dreaming night,
+  -- the same shape as sunpetal/nightcap's light-versus-shade curdle above),
+  -- so that pairing curdles instead of brewing.
+  [pairKey(Alchemy.MOONBELL, Alchemy.MOONBELL)] = { effect = "confuse" },
+  [pairKey(Alchemy.SUNPETAL, Alchemy.MOONBELL)] = CURDLE,
+  [pairKey(Alchemy.BLOODROOT, Alchemy.MOONBELL)] = { effect = "clarity" },
+  [pairKey(Alchemy.EMBERLEAF, Alchemy.MOONBELL)] = { effect = "blind" },
+  [pairKey(Alchemy.FROSTMOSS, Alchemy.MOONBELL)] = { effect = "levitate" },
+  [pairKey(Alchemy.NIGHTCAP, Alchemy.MOONBELL)] = { effect = "poison", power = 6 },
+}
+
+function Alchemy.herb(key)
+  return { kind = Items.HERB, herb = key, name = Alchemy.names[key] .. " herb", glyph = ";" }
+end
+
+-- The fixed outcome for brewing herbA with herbB together, order
+-- independent. Returns nil only when either key names no known herb.
+function Alchemy.lookup(herbA, herbB)
+  if not Alchemy.names[herbA] or not Alchemy.names[herbB] then return nil end
+  return Alchemy.recipes[pairKey(herbA, herbB)]
+end
+
+-- Resolves a completed brew into a fresh potion item, or (nil, "curdle") for
+-- an opposed pairing - the caller decides what a curdle does to the brewer.
+function Alchemy.brew(herbA, herbB)
+  local recipe = Alchemy.lookup(herbA, herbB)
+  if not recipe then return nil, "unknown herb" end
+  if recipe.curdle then return nil, "curdle" end
+  return Items.potionOf(recipe.effect, recipe.power)
+end
+
+return Alchemy

src/analytics.lua

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+-- Aggregate, read-only statistics over meta.lua's own cross-run history:
+-- how often a body of runs actually won, which class shows up most among
+-- them, and where a fresh score would land against that history - three
+-- questions renown and achievements never answer on their own, since both
+-- only ever look at the one run in front of them, never the shape of every
+-- run that came before it.
+
+local Analytics = {}
+
+-- Fraction of recorded runs that ended in victory. 0 for a state that has
+-- not recorded any runs yet rather than dividing by zero.
+function Analytics.winRate(meta)
+  if meta.totalRuns == 0 then return 0 end
+  return meta.wins / meta.totalRuns
+end
+
+-- Mean score across every leaderboard entry (see leaderboard.lua), 0 for an
+-- empty board.
+function Analytics.averageScore(board)
+  if #board == 0 then return 0 end
+  local total = 0
+  for _, entry in ipairs(board) do total = total + entry.score end
+  return total / #board
+end
+
+-- The className appearing most often on `board`, ties broken toward
+-- whichever class was seen first on the board - so the answer only ever
+-- depends on the board's own entry order, never on however pairs() happens
+-- to walk a count table. nil for an empty board.
+function Analytics.favoriteClass(board)
+  local counts, order = {}, {}
+  for _, entry in ipairs(board) do
+    if not counts[entry.className] then order[#order + 1] = entry.className end
+    counts[entry.className] = (counts[entry.className] or 0) + 1
+  end
+  local best, bestCount = nil, 0
+  for _, className in ipairs(order) do
+    if counts[className] > bestCount then
+      best, bestCount = className, counts[className]
+    end
+  end
+  return best
+end
+
+-- How many of `board`'s entries `score` would actually outrank, as a
+-- fraction from 0 (worse than or tied with everything) to 1 (better than
+-- everything). An empty board always answers 1 - there is nothing left to
+-- beat, so nothing holds the score back.
+function Analytics.percentile(board, score)
+  if #board == 0 then return 1 end
+  local beaten = 0
+  for _, entry in ipairs(board) do
+    if score > entry.score then beaten = beaten + 1 end
+  end
+  return beaten / #board
+end
+
+return Analytics