V2 Phase 3: combat rules automation (conditions, damage types, reminders)

Completes the deployable Phase 1-3 chunk: the combat tracker now runs the math.

- condition-effects engine: declarative CONDITION_EFFECTS_5E/PF2E table +
  deriveState(system, speed, conditions) → effective speed / advantage state /
  incapacitation / pf2e status penalty. Tracker shows effect badges
  ("Speed 0", "Disadv. attacks", "−2 status"); pure + 10 unit tests.
- damage types: applyDamage(c, amount, type?) consults snapshotted monster
  DamageDefenses (immune→0, resist→halve, vulnerable→double), back-compatible.
  Monster add snapshots damageDefenses; tracker shows a type picker only when a
  creature has typed defenses, and the log notes resisted/vulnerable amounts.
- concentration + death saves are surfaced as REMINDERS, never auto-rolled:
  damaging a concentrating PC logs "roll a DC N Con save…"; a downed PC's turn
  logs "make a death saving throw." The player rolls and resolves via the Drop
  button / death-save pips they already own. (Per user: no auto dice rolls —
  it removes the player from their character.)

Build + 271 unit tests green. Verified live: grapple → Speed 0 badge;
fire-immune creature shows the immune-labelled damage picker.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/features/combat/EncounterTracker.tsx

@@ -23,6 +23,7 @@ import { createRng } from '@/lib/rng';
 import { rollDice } from '@/lib/dice/notation';
 import { getSystem, getConditions, type SystemId } from '@/lib/rules';
 import { computeBudget, DIFFICULTY_COLOR } from '@/lib/combat/budget';
+import { deriveState, DAMAGE_TYPES, concentrationDC } from '@/lib/mechanics';
 import { useCharacters, useAllPcs } from '@/features/characters/hooks';
 import { useConditionGlossary } from './useConditionGlossary';
 import {
@@ -66,6 +67,36 @@ export function EncounterTracker({ encounter, campaign }: { encounter: Encounter
     if (prev) void encountersRepo.save(prev);
   };
 
+  /** The Character backing a PC/NPC combatant, if any (for cross-doc rules state). */
+  const pcCharacter = (combatant: Combatant): Character | undefined =>
+    combatant.kind !== 'monster' && combatant.characterId
+      ? [...allPcs, ...characters].find((ch) => ch.id === combatant.characterId)
+      : undefined;
+
+  /**
+   * After a concentrating PC takes damage, the app computes the Constitution
+   * save DC and surfaces it — but never rolls. The player rolls their own save
+   * and, on a failure, uses the Drop button on their sheet/panel. (Auto-rolling
+   * would take the moment away from the player.)
+   */
+  const noteConcentrationCheck = (combatant: Combatant, damage: number) => {
+    if (damage <= 0) return;
+    const ch = pcCharacter(combatant);
+    if (!ch?.concentration) return;
+    const dc = concentrationDC(damage);
+    void encountersRepo.mutate(encounter.id, (e) =>
+      logEvent(e, `${ch.name}: roll a DC ${dc} Constitution save or lose concentration on ${ch.concentration!.spellName}.`));
+  };
+
+  /** Advance the turn; remind (don't roll) when a downed PC's turn begins. */
+  const advanceTurn = () => {
+    mutate(nextTurn);
+    const upcoming = currentCombatant(nextTurn(encounter));
+    if (upcoming && upcoming.kind !== 'monster' && upcoming.hp.current <= 0 && pcCharacter(upcoming)) {
+      void encountersRepo.mutate(encounter.id, (e) => logEvent(e, `${upcoming.name} is down — make a death saving throw.`));
+    }
+  };
+
   const rollAllInitiative = () => {
     const rolls: Record<string, number> = {};
     for (const c of encounter.combatants) rolls[c.id] = rollDice('1d20', createRng()).total + c.initBonus;
@@ -148,7 +179,7 @@ export function EncounterTracker({ encounter, campaign }: { encounter: Encounter
               <Button variant="secondary" onClick={() => mutate(previousTurn)}>
                 <ChevronLeft size={15} aria-hidden /> Prev
               </Button>
-              <Button variant="primary" onClick={() => mutate(nextTurn)}>
+              <Button variant="primary" onClick={advanceTurn}>
                 Next turn <ChevronRight size={15} aria-hidden />
               </Button>
               <Button variant="ghost" className="text-danger" onClick={() => mutate(endEncounter)}>
@@ -185,7 +216,15 @@ export function EncounterTracker({ encounter, campaign }: { encounter: Encounter
               glossary={glossary}
               isCurrent={isActive && idx === encounter.turnIndex}
               onChange={(patch) => mutate((e) => updateCombatant(e, c.id, patch))}
-              onDamage={(amt) => mutate((e) => logEvent(updateCombatant(e, c.id, { hp: applyDamage(c, amt).hp }), `${c.name} takes ${amt} damage`))}
+              onDamage={(amt, type) => {
+                const after = applyDamage(c, amt, type);
+                const hpLoss = (c.hp.current - after.hp.current) + (c.hp.temp - after.hp.temp);
+                const note = hpLoss === amt
+                  ? `${c.name} takes ${amt}${type ? ` ${type}` : ''} damage`
+                  : `${c.name} takes ${hpLoss}${type ? ` ${type}` : ''} damage (${amt} before ${hpLoss < amt ? 'resistance' : 'vulnerability'})`;
+                mutate((e) => logEvent(updateCombatant(e, c.id, { hp: after.hp }), note));
+                noteConcentrationCheck(c, hpLoss);
+              }}
               onHeal={(amt) => mutate((e) => logEvent(updateCombatant(e, c.id, { hp: applyHealing(c, amt).hp }), `${c.name} heals ${amt}`))}
               onMove={(dir) => mutate((e) => moveCombatant(e, c.id, dir))}
               onRemove={() => mutate((e) => logEvent(removeCombatant(e, c.id), `${c.name} removed`))}
@@ -357,12 +396,16 @@ function CombatantRow({
   glossary: Map<string, string>;
   isCurrent: boolean;
   onChange: (patch: Partial<Combatant>) => void;
-  onDamage: (amt: number) => void;
+  onDamage: (amt: number, type?: string) => void;
   onHeal: (amt: number) => void;
   onMove: (dir: -1 | 1) => void;
   onRemove: () => void;
 }) {
   const [delta, setDelta] = useState(0);
+  const [dmgType, setDmgType] = useState('');
+  // Only show the damage-type picker when this creature actually has typed defenses.
+  const def = c.damageDefenses;
+  const hasDefenses = !!def && (def.resist.length > 0 || def.immune.length > 0 || def.vulnerable.length > 0);
   const dead = c.hp.current <= 0;
   const foe = c.kind === 'monster';
   const ratio = c.hp.max > 0 ? c.hp.current / c.hp.max : 0;
@@ -440,12 +483,31 @@ function CombatantRow({
               ))}
             </div>
           )}
+          {/* Mechanical consequences the conditions impose (enforced read-model). */}
+          {(() => {
+            const st = deriveState(system, 30, c.conditions);
+            return st.badges.length > 0 ? (
+              <div className="mt-1 flex flex-wrap gap-1" aria-label="Condition effects">
+                {st.badges.map((b) => (
+                  <span key={b} className="rounded border border-line bg-surface px-1.5 py-0.5 text-[10px] font-medium text-muted">{b}</span>
+                ))}
+              </div>
+            ) : null;
+          })()}
         </div>
 
         {/* HP controls */}
         <div className="flex items-center gap-1">
           <NumberField className="w-14" value={delta} min={0} onChange={setDelta} aria-label={`${c.name} HP amount`} />
-          <Button size="sm" variant="danger" disabled={delta <= 0} onClick={() => { onDamage(delta); setDelta(0); }} title="Apply damage">
+          {hasDefenses && (
+            <Select className="w-auto py-1 text-xs" value={dmgType} onChange={(e) => setDmgType(e.target.value)} aria-label={`${c.name} damage type`}>
+              <option value="">untyped</option>
+              {DAMAGE_TYPES.filter((t) => t !== 'untyped').map((t) => (
+                <option key={t} value={t}>{def!.immune.includes(t) ? `${t} (immune)` : def!.resist.includes(t) ? `${t} (resist)` : def!.vulnerable.includes(t) ? `${t} (vuln)` : t}</option>
+              ))}
+            </Select>
+          )}
+          <Button size="sm" variant="danger" disabled={delta <= 0} onClick={() => { onDamage(delta, dmgType || undefined); setDelta(0); }} title="Apply damage">
             <Sword size={14} aria-hidden /> Dmg
           </Button>
           <Button size="sm" variant="secondary" disabled={delta <= 0} onClick={() => { onHeal(delta); setDelta(0); }} title="Heal">

src/features/compendium/CompendiumPage.tsx

@@ -11,6 +11,7 @@ import { addCombatant } from '@/lib/combat/engine';
 import { charactersRepo, encountersRepo } from '@/lib/db/repositories';
 import { type Character, type InventoryItem, type SpellEntry, newSpellEntry } from '@/lib/schemas';
 import type { Spell, CompendiumEntry } from '@/lib/compendium/types';
+import type { CombatantDamageDefenses } from '@/lib/schemas/encounter';
 import { normalizeSpell5e, normalizeSpellPf2e } from '@/lib/mechanics';
 import { useUiStore } from '@/stores/uiStore';
 import { useActiveCampaign } from '@/features/campaigns/hooks';
@@ -295,7 +296,7 @@ function ActionBar({ children }: { children: React.ReactNode }) {
   );
 }
 
-function AddToCombat({ stats }: { stats: { name: string; ac: number; hp: number; initBonus: number; cr?: number; level?: number } }) {
+function AddToCombat({ stats }: { stats: { name: string; ac: number; hp: number; initBonus: number; cr?: number; level?: number; damageDefenses?: CombatantDamageDefenses } }) {
   const activeEncounterId = useUiStore((s) => s.activeEncounterId);
   const [msg, setMsg] = useState<string | null>(null);
 
@@ -312,6 +313,7 @@ function AddToCombat({ stats }: { stats: { name: string; ac: number; hp: number;
         conditions: [], notes: '',
         ...(stats.cr !== undefined ? { cr: stats.cr } : {}),
         ...(stats.level !== undefined ? { level: stats.level } : {}),
+        ...(stats.damageDefenses ? { damageDefenses: stats.damageDefenses } : {}),
       }),
     );
     setMsg(`Added to "${enc.name}" (init ${initiative}).`);

src/features/compendium/registry.tsx

@@ -1,6 +1,8 @@
 import type { ReactNode } from 'react';
 import type { SystemId } from '@/lib/rules';
 import { abilityModifier } from '@/lib/rules';
+import { normalizeMonsterDefenses } from '@/lib/mechanics';
+import type { CombatantDamageDefenses } from '@/lib/schemas/encounter';
 import type { CompendiumEntry, Monster, Spell, MagicItem } from '@/lib/compendium/types';
 import {
   loadMonsters,
@@ -49,7 +51,7 @@ export interface CategoryDef {
   /** enables "add to character" for spells/items */
   linkAs?: 'spell' | 'item';
   /** enables "add to combat" for monsters/creatures */
-  toCombatant?: (e: Entry) => { name: string; ac: number; hp: number; initBonus: number; cr?: number; level?: number };
+  toCombatant?: (e: Entry) => { name: string; ac: number; hp: number; initBonus: number; cr?: number; level?: number; damageDefenses?: CombatantDamageDefenses };
   /** optional numeric sort axis (e.g. CR, spell level) in addition to name */
   numericSort?: { label: string; get: (e: Entry) => number };
 }
@@ -169,6 +171,7 @@ export const CATEGORIES: CategoryDef[] = [
         name: m.name, ac: m.armor_class ?? 10, hp: m.hit_points ?? 1,
         initBonus: abilityModifier(m.dexterity ?? 10),
         ...(m.cr !== undefined ? { cr: m.cr } : {}),
+        damageDefenses: normalizeMonsterDefenses(m),
       };
     },
     numericSort: { label: 'CR', get: (e) => Number(e.cr) },