fix(client): table-driven missile ids and derived character stats (P3)

- MISSILE_ID_TO_KEY derived from CANONICAL_113C_MISSILES (Missiles.txt row ids);
  client visual aliases flagged clientAlias and excluded; 4 wrong ids corrected
  (firewallmaker 68, blaze 67, infernoflame1/2 60/61).
- No 'firebolt' / 'SO' substitution: unknown missile ids are not drawn
  (MIS_<id> token), unknown player class ids throw.
- derived-stats.ts: AR/defense/resists from CharStats ToHitFactor and
  DifficultyLevels ResistPenalty (pure helper + tests).

src/client/ui-model/derived-stats.ts

@@ -0,0 +1,85 @@
+/**
+ * Character sheet derived values (attack rating, defense, resistances) computed from 1.13c tables.
+ *
+ * The 1.13c server does not send these totals: D2Client derives them from the unit StatList and
+ * `CharStats.txt` / `DifficultyLevels.txt`. Inputs here are the server StatList (absent stat = 0),
+ * the class `ToHitFactor` (`CANONICAL_CHARSTATS`) and the difficulty `ResistPenalty`.
+ *
+ * Formulas (1.13c):
+ * - Attack rating  = (Dexterity - 7) * 5 + ToHitFactor + stat 19 `tohit`, scaled by stat 119 `item_tohit_percent`.
+ * - Defense        = floor(Dexterity / 4) + stat 31 `armorclass`.
+ * - Resistance     = min(75 + stat `max*resist`, stat `*resist` + ResistPenalty) for fire/light/cold/poison
+ *                    (stats 39/41/43/45, max stats 40/42/44/46).
+ *
+ * Equipment item stats are only included once they are aggregated into the self StatList.
+ */
+import { RAW_DIFFICULTY_LEVELS } from '../../common/data/canonical-drop-data.ts'
+import { CANONICAL_CHARSTATS, type CharacterClassCode } from '../../common/units/classes.ts'
+
+export interface StatReader {
+  get(statId: number): number
+}
+
+export interface CharacterSheetDerived {
+  readonly attackRating: number
+  readonly defense: number
+  readonly fireRes: number
+  readonly coldRes: number
+  readonly lightRes: number
+  readonly poisRes: number
+}
+
+const STAT_DEXTERITY = 2
+const STAT_TOHIT = 19
+const STAT_ARMORCLASS = 31
+const STAT_ITEM_TOHIT_PERCENT = 119
+const STAT_FIRERESIST = 39
+const STAT_MAXFIRERESIST = 40
+const STAT_LIGHTRESIST = 41
+const STAT_MAXLIGHTRESIST = 42
+const STAT_COLDRESIST = 43
+const STAT_MAXCOLDRESIST = 44
+const STAT_POISONRESIST = 45
+const STAT_MAXPOISONRESIST = 46
+const BASE_MAX_RESIST = 75
+
+function parseResistPenalties(raw: string): readonly number[] {
+  const lines = raw.split(/\r?\n/).filter((l) => l.trim() !== '')
+  const header = lines[0]!.split('\t')
+  const idx = header.indexOf('ResistPenalty')
+  if (idx < 0) throw new Error('DifficultyLevels.txt: missing ResistPenalty column')
+  const out = lines.slice(1).map((l) => Number(l.split('\t')[idx]))
+  if (out.length !== 3 || out.some((v) => !Number.isFinite(v))) {
+    throw new Error('DifficultyLevels.txt: expected 3 rows with numeric ResistPenalty')
+  }
+  return out
+}
+
+/** `DifficultyLevels.txt` `ResistPenalty` per difficulty (Normal / Nightmare / Hell). */
+export const RESIST_PENALTY_BY_DIFFICULTY: readonly number[] = parseResistPenalties(RAW_DIFFICULTY_LEVELS)
+
+function resist(stats: StatReader, statId: number, maxStatId: number, penalty: number): number {
+  return Math.min(BASE_MAX_RESIST + stats.get(maxStatId), stats.get(statId) + penalty)
+}
+
+export function computeCharacterSheetDerived(
+  classCode: CharacterClassCode,
+  stats: StatReader,
+  difficulty: 0 | 1 | 2,
+): CharacterSheetDerived {
+  const charStats = CANONICAL_CHARSTATS[classCode]
+  if (!charStats) throw new Error(`computeCharacterSheetDerived: no CharStats row for class ${classCode}`)
+  const penalty = RESIST_PENALTY_BY_DIFFICULTY[difficulty]
+  if (penalty === undefined) throw new Error(`computeCharacterSheetDerived: invalid difficulty ${difficulty}`)
+  const dex = stats.get(STAT_DEXTERITY)
+  const baseAr = (dex - 7) * 5 + charStats.toHitFactor + stats.get(STAT_TOHIT)
+  const attackRating = Math.floor((baseAr * (100 + stats.get(STAT_ITEM_TOHIT_PERCENT))) / 100)
+  return {
+    attackRating,
+    defense: Math.floor(dex / 4) + stats.get(STAT_ARMORCLASS),
+    fireRes: resist(stats, STAT_FIRERESIST, STAT_MAXFIRERESIST, penalty),
+    coldRes: resist(stats, STAT_COLDRESIST, STAT_MAXCOLDRESIST, penalty),
+    lightRes: resist(stats, STAT_LIGHTRESIST, STAT_MAXLIGHTRESIST, penalty),
+    poisRes: resist(stats, STAT_POISONRESIST, STAT_MAXPOISONRESIST, penalty),
+  }
+}

src/client/view/unit-drawables.ts

@@ -1,4 +1,4 @@
-import { getMissileTxtData } from '../../common/skills/missiles-data.ts'
+import { CANONICAL_113C_MISSILES, getMissileTxtData } from '../../common/skills/missiles-data.ts'
 import type { UnitKind, UnitSnapshot } from '../../netproto/index.ts'
 import type { PointLightInput } from '../scene/lighting-presets.ts'
 import { subTileToWorldOrtho } from './viewport-profile.ts'
@@ -112,39 +112,17 @@ export type SceneEntityDrawable =
   | SceneOverlayDrawable
 
 /**
- * Canonical 1.13c `Missiles.txt` ID -> internal missile key lookup for D2GS missile units.
+ * 1.13c `Missiles.txt` row id (D2GS missile unit classId) -> missile key, derived from
+ * `CANONICAL_113C_MISSILES` (Missiles.txt rows only; client visual aliases excluded).
+ * Ids without art data are absent: callers must treat them as unknown, never substitute another missile.
  */
-export const MISSILE_ID_TO_KEY: Readonly<Record<number, string>> = {
+export const MISSILE_ID_TO_KEY: Readonly<Record<number, string>> = Object.freeze(
-  1: 'arrow',
+  Object.fromEntries(
-  2: 'javelin',
+    Object.entries(CANONICAL_113C_MISSILES)
-  6: 'magicarrow',
+      .filter(([, m]) => m.clientAlias !== true)
-  9: 'firearrow',
+      .map(([key, m]) => [m.id, key] as const),
-  11: 'coldarrow',
+  ),
-  14: 'guidedarrow',
+)
-  28: 'firebolt',
-  29: 'fireball',
-  35: 'chargedbolt',
-  41: 'lightning',
-  44: 'nova',
-  49: 'icebolt',
-  53: 'iceblast',
-  55: 'glacialspike',
-  56: 'meteor',
-  59: 'blizzard',
-  63: 'chainlightning',
-  64: 'frostnova',
-  83: 'poisonnova',
-  92: 'bonespear',
-  93: 'bonespirit',
-  97: 'teeth',
-  101: 'holybolt',
-  102: 'blessedhammer',
-  165: 'frozenorb',
-  232: 'firestorm',
-  235: 'moltenboulder',
-  244: 'twister',
-  245: 'tornado',
-}
 
 export interface OverlayMeta {
   readonly overlayId: number
@@ -186,11 +164,14 @@ export function resolveUnitToken(unit: RenderableUnitInput): string {
     return unit.token.trim()
   }
   if (unit.kind === 'player') {
-    return PLAYER_CLASS_TOKENS[unit.classId] ?? 'SO'
+    const token = PLAYER_CLASS_TOKENS[unit.classId]
+    if (!token) throw new Error(`resolveUnitToken: unknown player class id ${unit.classId}`)
+    return token
   }
   if (unit.kind === 'missile') {
-    const key = MISSILE_ID_TO_KEY[unit.classId] ?? 'firebolt'
+    const key = MISSILE_ID_TO_KEY[unit.classId]
-    return getMissileTxtData(key).celFile
+    // Unknown missile ids keep an explicit unresolved token (like OBJ_/MON_) instead of borrowing another missile.
+    return key ? getMissileTxtData(key).celFile : `MIS_${unit.classId}`
   }
   if (unit.kind === 'object') {
     return `OBJ_${unit.classId}`
@@ -204,11 +185,12 @@ export function resolveUnitToken(unit: RenderableUnitInput): string {
 export function resolveMissileMetadata(
   classId: number,
   explicitToken?: string,
-): { readonly key: string; readonly entry: MissileTxtEntry } {
+): { readonly key: string; readonly entry: MissileTxtEntry } | null {
   const key =
     explicitToken && explicitToken.trim() !== ''
       ? explicitToken.trim().toLowerCase()
-      : (MISSILE_ID_TO_KEY[classId] ?? 'firebolt')
+      : MISSILE_ID_TO_KEY[classId]
+  if (!key) return null
   return {
     key,
     entry: getMissileTxtData(key),
@@ -271,7 +253,9 @@ export function buildSceneDrawables(
     const { x: worldX, y: worldY } = subTileToWorldOrtho(unit.x, unit.y, originX, originY)
 
     if (unit.kind === 'missile') {
-      const { key, entry } = resolveMissileMetadata(unit.classId, unit.token)
+      const resolved = resolveMissileMetadata(unit.classId, unit.token)
+      if (!resolved) continue // Unknown Missiles.txt id: not drawn (no substitute art).
+      const { key, entry } = resolved
       const blendMode: DrawableBlendMode = entry.trans === 1 ? 'additive' : 'normal'
       const dir = computeDirection8Or16(
         unit.x,

src/common/skills/missiles-data.ts

@@ -188,6 +188,11 @@ export const FACING_VECTORS: readonly (readonly [number, number])[] = [
 export interface MissileTxtData {
   readonly name: string
   readonly id: number
+  /**
+   * `true` for client-side visual aliases that are NOT rows of 1.13c Missiles.txt (their `id` points at the
+   * real row they render for). Aliases are excluded from the wire id -> missile key lookup.
+   */
+  readonly clientAlias?: boolean | undefined
   readonly vel: number
   readonly maxVel: number
   readonly range: number
@@ -261,6 +266,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   lightning: {
     name: 'lightning',
+    clientAlias: true,
     id: 98,
     vel: 30,
     maxVel: 30,
@@ -326,6 +332,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   thunderstorm: {
     name: 'thunderstorm',
+    clientAlias: true,
     id: 166,
     vel: 2,
     maxVel: 2,
@@ -370,6 +377,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   electricnova: {
     name: 'electricnova',
+    clientAlias: true,
     id: 90,
     vel: 24,
     maxVel: 24,
@@ -584,6 +592,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   freezeexplode: {
     name: 'freezeexplode',
+    clientAlias: true,
     id: 88,
     vel: 0,
     maxVel: 0,
@@ -626,6 +635,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   glacialspikeejecta: {
     name: 'glacialspikeejecta',
+    clientAlias: true,
     id: 89,
     vel: 0,
     maxVel: 0,
@@ -920,6 +930,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   hydrafire: {
     name: 'hydrafire',
+    clientAlias: true,
     id: 247,
     vel: 16,
     maxVel: 16,
@@ -941,7 +952,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   firewallmaker: {
     name: 'firewallmaker',
-    id: 82,
+    id: 68,
     vel: 0,
     maxVel: 0,
     range: 1,
@@ -983,6 +994,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   groundfirebig: {
     name: 'groundfirebig',
+    clientAlias: true,
     id: 83,
     vel: 0,
     maxVel: 0,
@@ -1004,7 +1016,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   blaze: {
     name: 'blaze',
-    id: 80,
+    id: 67,
     vel: 0,
     maxVel: 0,
     range: 90,
@@ -1025,7 +1037,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   infernoflame1: {
     name: 'infernoflame1',
-    id: 72,
+    id: 60,
     vel: 12,
     maxVel: 12,
     range: 16,
@@ -1046,7 +1058,7 @@ export const CANONICAL_113C_MISSILES: Readonly<Record<string, MissileTxtData>> =
   },
   infernoflame2: {
     name: 'infernoflame2',
-    id: 73,
+    id: 61,
     vel: 12,
     maxVel: 12,
     range: 16,

tests/client/derived-stats.test.ts

@@ -0,0 +1,29 @@
+import { describe, expect, it } from 'vitest'
+import {
+  RESIST_PENALTY_BY_DIFFICULTY,
+  computeCharacterSheetDerived,
+} from '../../src/client/ui-model/derived-stats.ts'
+
+function statsOf(entries: Record<number, number>) {
+  return { get: (id: number) => entries[id] ?? 0 }
+}
+
+describe('character sheet derived values (1.13c tables)', () => {
+  it('reads ResistPenalty from DifficultyLevels.txt', () => {
+    expect(RESIST_PENALTY_BY_DIFFICULTY).toEqual([0, -40, -100])
+  })
+
+  it('level-1 Assassin (dex 20, no bonuses)', () => {
+    const d = computeCharacterSheetDerived('ass', statsOf({ 2: 20 }), 0)
+    expect(d.attackRating).toBe((20 - 7) * 5 + 15)
+    expect(d.defense).toBe(5)
+    expect([d.fireRes, d.coldRes, d.lightRes, d.poisRes]).toEqual([0, 0, 0, 0])
+  })
+
+  it('applies difficulty penalty and the 75 + max-resist cap', () => {
+    const d = computeCharacterSheetDerived('sor', statsOf({ 2: 25, 39: 200, 40: 5, 43: 30 }), 2)
+    expect(d.fireRes).toBe(80)
+    expect(d.coldRes).toBe(-70)
+    expect(d.attackRating).toBe((25 - 7) * 5 - 15)
+  })
+})

tests/client/missile-id-map.test.ts

@@ -0,0 +1,57 @@
+/**
+ * Audit regression: `MISSILE_ID_TO_KEY` must match 1.13c Missiles.txt (row id <-> Missile name),
+ * and unknown ids must not borrow another missile's art.
+ */
+import { readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+import { describe, expect, it } from 'vitest'
+import { MISSILE_ID_TO_KEY, resolveMissileMetadata, resolveUnitToken } from '../../src/client/view/unit-drawables.ts'
+
+function loadMissilesTxtIdToName(): Map<number, string> {
+  const text = readFileSync(resolve(__dirname, '../../samples/fixtures/data/global/excel/Missiles.txt'), 'utf8')
+  const lines = text.split(/\r?\n/)
+  const header = lines[0]!.split('\t')
+  const nameIdx = header.indexOf('Missile')
+  const idIdx = header.indexOf('Id')
+  const out = new Map<number, string>()
+  for (const line of lines.slice(1)) {
+    const cols = line.split('\t')
+    const name = (cols[nameIdx] ?? '').trim()
+    const id = Number(cols[idIdx])
+    if (name && Number.isInteger(id)) out.set(id, name.toLowerCase())
+  }
+  return out
+}
+
+describe('MISSILE_ID_TO_KEY vs Missiles.txt', () => {
+  const txt = loadMissilesTxtIdToName()
+
+  it('every mapped id names the same Missiles.txt row', () => {
+    const entries = Object.entries(MISSILE_ID_TO_KEY)
+    expect(entries.length).toBeGreaterThan(40)
+    for (const [id, key] of entries) {
+      expect(txt.get(Number(id)), `id ${id}`).toBe(key)
+    }
+  })
+
+  it('pins well-known 1.13c ids', () => {
+    expect(MISSILE_ID_TO_KEY[0]).toBe('arrow')
+    expect(MISSILE_ID_TO_KEY[56]).toBe('chargedbolt')
+    expect(MISSILE_ID_TO_KEY[58]).toBe('firebolt')
+    expect(MISSILE_ID_TO_KEY[59]).toBe('icebolt')
+    expect(MISSILE_ID_TO_KEY[62]).toBe('fireball')
+    expect(MISSILE_ID_TO_KEY[90]).toBe('nova')
+    expect(MISSILE_ID_TO_KEY[92]).toBe('blessedhammer')
+    expect(MISSILE_ID_TO_KEY[100]).toBe('meteor')
+    expect(MISSILE_ID_TO_KEY[260]).toBe('frozenorb')
+  })
+
+  it('unknown missile ids are explicit (no firebolt / SO substitution)', () => {
+    expect(resolveMissileMetadata(9999)).toBeNull()
+    expect(
+      resolveUnitToken({ id: 1, kind: 'missile', classId: 9999, x: 0, y: 0 } as any),
+    ).toBe('MIS_9999')
+    expect(() => resolveUnitToken({ id: 1, kind: 'player', classId: 7, x: 0, y: 0 } as any)).toThrow()
+    expect(resolveUnitToken({ id: 1, kind: 'player', classId: 6, x: 0, y: 0 } as any)).toBe('AI')
+  })
+})

tests/client/settings-toolbar-view.test.ts

@@ -396,7 +396,7 @@ describe('SceneSource, UnitDrawables, Missiles/Overlays & LightingInputs (F15, F
       {
         kind: 'missile',
         id: 200,
-        classId: 29, // FireBall (Trans: 1 additive)
+        classId: 62, // Missiles.txt row 62 = fireball (Trans: 1 additive)
         x: 102,
         y: 100,
         targetX: 110,
@@ -405,7 +405,7 @@ describe('SceneSource, UnitDrawables, Missiles/Overlays & LightingInputs (F15, F
       {
         kind: 'missile',
         id: 201,
-        classId: 1, // Arrow (Trans: 0 normal)
+        classId: 0, // Missiles.txt row 0 = arrow (Trans: 0 normal)
         x: 101,
         y: 101,
       },