Merge pull request 'feat(abilities): disasters & pandemics lever (v0.41.0)' (#76) from feat/63-disasters-pandemics into master

2026-10-16 11:20:16 +02:00
parent df52261835 c90e9ae753
commit 8d8d7772c9
14 changed files with 984 additions and 116 deletions
@@ -96,6 +96,15 @@ history/
 │   ├── map.ts              # GameState → RegionMap (region key → owner + stable color)
 │   ├── presets.ts          # load preset JSON files from disk
 │   ├── db.ts               # SQLite open/save/load (+ legacy regionStats migration on load, v0.28 #46)
+│   ├── abilities/          # the modular LLM-ability system (v0.40.0 #67) — one file per world lever
+│   │   ├── index.ts        #   the ABILITIES registry (list order = apply order) + the re-export surface
+│   │   ├── types.ts        #   the Ability contract + the AbilityField union
+│   │   ├── shared.ts       #   shared helpers (stat dips / re-derive / ref resolution, …)
+│   │   ├── apply-helpers.ts  #   shared apply-path helpers
+│   │   ├── <name>.ts       #   one module per ability: wars / takeovers / leaders / nuclear /
+│   │   │                   #     ideology / industry / economy / hybrid / disasters (v0.41.0 #63)
+│   │   ├── *.test.ts       #   per-ability unit tests (registry.test.ts pins the 9-ability contract)
+│   │   └── goldens/        #   pinned prompt goldens (system-no-tool / system-tool / user)
 │   └── *.test.ts           # unit tests (vitest)
 └── src/
    ├── App.tsx             # screen router (home → pick → game) + manual hash router (#/game/<id>); owns game/regions/advisors/busy
@@ -442,6 +451,64 @@ history/
  (`industry: { projects: [] }`) — e2e (CI, `LLM_STUB=1`) is unaffected and the path is unit-tested
  only (`server/engine.test.ts`, `server/protocol.test.ts`, `server/regions.test.ts`,
  `server/db.test.ts`, `scripts/build-region-resources.test.ts`).
+- **Modular LLM abilities — how to add a new one (v0.40.0, #67).**
+  Since v0.40.0 the per-feature LLM levers are a modular registry in `server/abilities/`: one
+  file per ability plus `types.ts` (the `Ability<K>` interface, the closed `AbilityField` union,
+  and the `AbilityCtx` / `UserPromptCtx` shapes), `shared.ts` (the dependency-free `str` /
+  `resolveNationRef` / `resolveRegionKey` / fresh-id primitives the abilities share), and
+  `index.ts` (the ordered `ABILITIES` array — its position is the canonical apply / prompt /
+  payload order). Each ability is a plain object implementing `Ability<K>`: `field` (its
+  `TurnResult` field name), `default()` (a FRESH no-op value), `validate(raw)` (defensive parse
+  into the field's exact shape — never throws), `apply(state, data, ctx)` (mutate the world in
+  place — never throws), `schemaLine()` (its system-prompt JSON line), `constraint()` (its HARD
+  CONSTRAINTS bullet), `isMeaningful(data)` (does a non-default value make the turn meaningful?),
+  `stateFields?` (the `GameState` fields it owns, for the `db.ts` legacy-row migration —
+  `undefined` for turn-transient abilities), `stub()` (the deterministic stub's value — every
+  ability returns `default()`, so e2e is never affected), and `payload(ctx)` (the user-payload
+  keys it contributes — `{}` for turn-transient ones). The engine consumes the registry
+  generically and is never edited to add an ability: `buildSystemPrompt` emits each
+  `schemaLine()` / `constraint()` in `ABILITIES` order (between the `nationOps` block/line and the
+  `markers` line / "- Prefer 1-4 events" bullet), `buildUserPrompt` merges each `payload()` at its
+  historical position, `validateTurnResult` fills each field via `a.validate()`, `isMeaningful`
+  ORs the per-ability predicates, `applyTurnResult` runs `a.apply` in `ABILITIES` order (after the
+  core effects, before markers), the stub fills each field via `a.stub()`, and the "unclear"
+  fallback uses `a.default()`. To add a new ability: (1) add the field's type to `TurnResult` in
+  `shared/protocol.ts` (a required field with a default) and the field name to the `AbilityField`
+  union in `types.ts`; (2) create `server/abilities/<name>.ts` exporting an `Ability<'<name'>`
+  const; (3) import it in `index.ts` and APPEND it to `ABILITIES` (append last — never reorder
+  existing entries; their order is pinned by the goldens and the stub's byte-identical output);
+  (4) re-export any new public names from `index.ts` and from `engine.ts`; (5) if it owns a durable
+  `GameState` field, add it to `shared/types.ts` + the `db.ts` legacy-row migration (additive,
+  never wiped) and declare it in `stateFields`; if it contributes to the user payload, return its
+  keys from `payload()` and extend `UserPromptCtx`; (6) write `server/abilities/<name>.test.ts`
+  (the stub never exercises a new ability, so its apply path is unit-tested only) and — if it
+  changes the system prompt — regenerate the goldens
+  (`REGEN_GOLDENS=1 npx vitest run server/abilities/registry.test.ts`); `user.txt` must stay
+  byte-identical unless the new ability contributes user-payload keys.
+- **Disasters & pandemics — natural / man-made catastrophes with a deterministic dip (v0.41.0, #63).**
+  `TurnResult.disasters = DisastersOps = { events: DisasterEvent[] }` (required, default
+  `{ events: [] }`); `DisasterEvent = { type, target, severity, detail? }` with `type ∈
+  DISASTER_TYPES = earthquake | flood | volcanic | wildfire | famine | plague | epidemic` and
+  `severity ∈ DISASTER_SEVERITIES = minor | moderate | severe`. Like the hybrid layer this is
+  **turn-transient**: it owns NO `GameState` field (no durable list, no `db.ts` change) — a
+  plague or epidemic that persists is simply re-declared each turn it continues. The DETERMINISTIC
+  `DISASTER_EFFECTS` table (`server/abilities/disasters.ts`) maps each `(type, severity)` to a
+  small set of signed stat deltas (a severe plague is the hardest hit; none of them touch
+  `population`, and none move borders — sole ownership is untouched). The `target` resolves like a
+  hybrid op — a nation ref via the shared `resolveNationRef` (id first, then a case-insensitive
+  unique name), else a region key that hits that region's SOLE owner (a key with 0 or 2+ owners, or
+  one absent from the valid-keys manifest, is dropped); there is no `from`/actor field — a
+  catastrophe is not an attack — so (unlike hybrid) a self-target drop does NOT apply.
+  `applyDisasterEvent` (run in the `ABILITIES` loop after territory / wars / economy, before
+  markers) dips the target nation's `stats` (clamped 0–100), mirrors the dip to its regions (the
+  single named region for a region target, else every region it owns — entries with no
+  `regionStats` are skipped), and re-derives the nation's aggregate stats (the same 0-region /
+  no-entry guards, so a 0-region nation keeps its directly-mutated value and the dip persists).
+  `payload()` is `{}` (turn-transient), so the user-prompt golden (`user.txt`) is unchanged; the
+  system prompt gains the field's schema line + constraint bullet (the system goldens were
+  re-baselined in v0.41.0). `isMeaningful` is `events.length > 0`. The stub never proposes a
+  disaster (`{ events: [] }`), so e2e (CI, `LLM_STUB=1`) is unaffected and the path is unit-tested
+  only (`server/abilities/disasters.test.ts`).
 - **Map click → dossier target (owner resolved from the RegionMap, by region key).**
  Clicking a sub-region does NOT open a popup — it switches the dossier to that sub-region's
  owning nation (`focusNation(ownerId, {name})` in `App.tsx`, which also records which region was
@@ -2,6 +2,22 @@

 All notable changes to **History** are listed here, newest first.

+## v0.41.0 — 2026-10-16 09:07
+- **#63: Disasters & pandemics — a `TurnResult.disasters` lever letting the LLM declare natural/man-made disasters (earthquake / flood / volcanic / wildfire / famine / plague / epidemic) on a nation or a region, with a deterministic stat dip (stability / economy / military).** It is a **turn-transient** feature, exactly like the v0.34 `hybrid` layer: **no new `GameState` field, no `db.ts` change, no durable list** — the ops are consumed inside `applyTurnResult` and leave nothing behind. It lands as the **9th ability** of the v0.40.0 modular system, in a new `server/abilities/disasters.ts` module, **registered last** in the `ABILITIES` registry (after `ideology`, before the loop appends `markers` / `nationOps`).
+  - **Types (`shared/protocol.ts`).** New `DisasterType` (`'earthquake' | 'flood' | 'volcanic' | 'wildfire' | 'famine' | 'plague' | 'epidemic'`), `DisasterSeverity` (`'minor' | 'moderate' | 'severe'`), `DisasterEvent` (`{ type; target; severity; detail? }` — `target` is a nation ref **or** a region key), and `DisastersOps` (`{ events: DisasterEvent[] }`); `TurnResult.disasters` is **required**, placed between `ideology` and `markers`, default `{ events: [] }`.
+  - **Ability module (`server/abilities/disasters.ts`).** `field: 'disasters'`; `default()` / `stub()` → a **fresh** `{ events: [] }` each call; `validate` wraps the exported `validateDisasterEvents` (defensive, never throws — accepts the `{ events: [...] }` object or a bare array; each event needs a valid `type`, a valid `severity`, and a non-empty `target` (trimmed, ≤120) — anything else is dropped, with a per-turn cap); `apply` runs `applyDisasterEvent` per event; `schemaLine()` / `constraint()` supply the prompt text; `payload()` → `{}` (no user-payload keys — targets resolve from the existing ref table); `isMeaningful` = `events.length > 0`; **no** `stateFields` (turn-transient, no durable `GameState` field).
+  - **Deterministic effects (`DISASTER_EFFECTS`).** A pure `(type, severity) → stat-dip` table — **no hidden randomness**. `population` is never touched. Earthquake and famine dip **both** `stability` and `economy` (−2 / −4 / −7 for minor / moderate / severe); flood dips `economy` (−2 / −3 / −6) and `stability` (−1 / −2 / −4); volcanic dips `economy` (−2 / −4 / −7) and `stability` (−2 / −3 / −6); wildfire dips **only** `economy` (−2 / −4 / −7); plague dips `stability` (−3 / −5 / −9) and `military` (−2 / −3 / −6); epidemic dips `stability` (−2 / −4 / −7) and `military` (−1 / −2 / −4).
+  - **Apply semantics (`applyDisasterEvent`).** The `target` is resolved exactly like a hybrid op (`resolveHybridTarget`): a resolvable nation ref hits every region the nation owns; a region key hits its **sole** owner; a 0-owner or 2+-owner region key is **dropped** (never thrown). The one deliberate difference from hybrid: a disaster has **no `from` field**, so there is **no self-target drop** — a nation may suffer a disaster it itself declared. The dip is clamped to 0–100, **mirrored to every region the target owns** (`regionStats`), and the target's derived `stats` is **re-derived** afterwards (the same 0-region / no-entry guards as hybrid / economy / industry — a 0-region nation keeps its directly-mutated value). It never moves territory (sole ownership is untouched). The **stub never** declares a disaster (`{ events: [] }`), so e2e (CI, `LLM_STUB=1`) is unaffected and the path is covered by unit tests only.
+  - **Registry & prompt.** `disasters` is added last in `ABILITIES`; the system prompt gains the `disasters` schema line and its constraint bullet ("at most 1–2 per turn, each narrated in `events`"); the user prompt is unchanged (`payload()` is `{}`). The two committed system-prompt **goldens** (`system-no-tool.txt`, `system-tool.txt`) are regenerated (each gains exactly the new `disasters` schema line + constraint bullet); the **`user.txt` golden stays byte-identical** (no new user-payload keys — verified by checksum).
+  - **Tests.** New `server/abilities/disasters.test.ts` (**33 tests**): the type/severity predicate sets; `validateDisasterEvents` (shape / leniency / drops / cap); `applyDisasterEvent` exact dips (nation target, single-region target, region gated by `validKeys`, clamping at 0, 0-owner / 2+-owner region drops, unknown-key drop, unknown / ambiguous ref drops, case-insensitive name resolve, 0-region direct-dip persistence, missing-`regionStats`-entry skip); and the ability const contract (field, no `stateFields`, fresh `default()`/`stub()`, `isMeaningful`, `payload() {}`, `validate` wrapping, `apply` ctx wiring). `registry.test.ts` is updated for the **9-ability** contract (order, fields, `fullDefaultTurn()`, `meaningfulFor`, re-export pin); the goldens are regenerated (verified idempotent).
+- **Secondary cleanups from the v0.40.0 refactor (folded into this release):**
+  - **AGENTS.md** — `server/abilities/` is added to the Layout tree (the per-ability files, tests, and goldens); Conventions gains a "Modular LLM abilities — how to add a new one (v0.40.0, #67)" bullet and a "Disasters & pandemics (v0.41.0, #63)" bullet.
+  - The **orphaned `validateTakeovers` JSDoc** (left over after the v0.40 refactor removed the function body) is deleted.
+  - Both **inline `as unknown` double-casts** are folded into the single top-level `./abilities` import (`AbilityCtx` + `UserPromptCtx` types).
+  - **`str()` is de-duplicated** — imported from `./abilities/shared` instead of the local copy.
+- **Guarantees.** No client (`src/`) changes, no new runtime deps, `shared/` keeps zero runtime deps, and no `@turf`/`@types/geojson` in any `.ts`. All unit tests green (additive); e2e (CI, `LLM_STUB=1`) unaffected (the stub is disasters-inert).
+- **Version** bumped `0.40.0 → 0.41.0`.
+
 ## v0.40.0 — 2026-10-16 07:14
 - **#67: Modular LLM-ability system — the 8 per-feature LLM abilities are extracted from `server/engine.ts` into an ordered `ABILITIES` registry (`server/abilities/`).** A pure, **behavior-preserving** refactor: each per-ability concern (validate / schema-line / constraint / payload / meaningfulness / apply / stub-default / durable-state-field) moves into one file per ability, assembled into a single ordered registry that the engine iterates uniformly. **Nothing observable changes** — the system prompt, user prompt, `applyTurnResult` world-state mutations, and the deterministic stub are all byte-for-byte identical to v0.39.0 (pinned by new golden fixtures + registry tests), and `server/engine.ts` re-exports every name its existing callers import, so `server/index.ts` and all tests work with zero edits.
  - **New `server/abilities/` package.**
@@ -1,6 +1,6 @@
 {
  "name": "history",
-  "version": "0.40.0",
+  "version": "0.41.0",
  "private": true,
  "type": "module",
  "description": "AI-driven alternate-history simulator — the LLM is the world engine (Pax Historia style).",
@@ -0,0 +1,445 @@
+// Unit tests for the DISASTERS & PANDEMICS ability (v0.41.0, #63) — the
+// modular, turn-transient LLM-ability that applies a deterministic
+// (type, severity) stat dip to a nation or a single region. This is the
+// ability's own test file (the registry's cross-cutting guarantees — order,
+// distinct fields, the system/user goldens — are covered by
+// ./registry.test.ts). The stub never proposes a disaster, so the apply path
+// is exercised here, not by the e2e suite.
+
+import { describe, expect, it } from 'vitest';
+
+import type { AbilityCtx } from './types';
+import {
+  DISASTER_EFFECTS,
+  DISASTER_SEVERITIES,
+  DISASTER_TYPES,
+  applyDisasterEvent,
+  disasters,
+  isDisasterSeverity,
+  isDisasterType,
+  validateDisasterEvents,
+} from './disasters';
+
+import type { DisasterEvent, DisastersOps } from '../../shared/protocol';
+import type { GameState, Nation, NationStats, RegionStats } from '../../shared/types';
+
+// ---------------------------------------------------------------------------
+// Fixture helpers
+// ---------------------------------------------------------------------------
+
+/** Build a NationStats from the four canonical indices (military, economy, stability, population). */
+function NS(military: number, economy: number, stability: number, population: number): NationStats {
+  return { military, economy, stability, population };
+}
+
+/** Build a RegionStats from the four canonical indices. */
+function RS(military: number, economy: number, stability: number, population: number): RegionStats {
+  return { military, economy, stability, population };
+}
+
+/** A minimal nation: the given id/name/stats/region-key territory, neutral relations. */
+function mkNation(id: string, name: string, stats: NationStats, territory: string[]): Nation {
+  return { id, name, type: 'major', stats, territory, relations: {} };
+}
+
+/**
+ * A minimal GameState carrying the given nations (keyed by id) and per-region
+ * stats. Every other required field is at its fresh-game baseline, so a test
+ * can focus purely on the disaster dip.
+ */
+function mkState(
+  nations: Record<string, Nation>,
+  regionStats: Record<string, RegionStats>,
+): GameState {
+  return {
+    id: 'g1',
+    presetId: 'test',
+    presetTitle: 'Test',
+    playerNationId: Object.keys(nations)[0] ?? 'uk',
+    turn: 1,
+    date: '1939-09-01',
+    nations,
+    events: [],
+    pending: [],
+    version: 1,
+    unowned: [],
+    pendingNationOps: [],
+    markers: [],
+    regionStats,
+    wars: [],
+    trades: [],
+    embargoes: [],
+    industry: [],
+  };
+}
+
+/** A minimal AbilityCtx for the ability's `apply` (no manifests loaded). */
+function mkCtx(state: GameState, validRegionKeys?: ReadonlySet<string>): AbilityCtx {
+  return {
+    previous: state,
+    actingTurn: state.turn,
+    ...(validRegionKeys ? { validRegionKeys } : {}),
+  };
+}
+
+// ---------------------------------------------------------------------------
+// Type / severity constants + predicates
+// ---------------------------------------------------------------------------
+
+describe('DISASTER_TYPES / DISASTER_SEVERITIES', () => {
+  it('exposes exactly the seven types and three severities', () => {
+    expect([...DISASTER_TYPES]).toEqual([
+      'earthquake',
+      'flood',
+      'volcanic',
+      'wildfire',
+      'famine',
+      'plague',
+      'epidemic',
+    ]);
+    expect([...DISASTER_SEVERITIES]).toEqual(['minor', 'moderate', 'severe']);
+  });
+
+  it('every (type, severity) pair dips at least one stat, never population', () => {
+    for (const t of DISASTER_TYPES) {
+      for (const s of DISASTER_SEVERITIES) {
+        const dips = DISASTER_EFFECTS[t][s];
+        expect(dips).toBeDefined();
+        const keys = Object.keys(dips);
+        expect(keys.length).toBeGreaterThan(0);
+        expect(keys).not.toContain('population');
+        for (const k of keys) expect(dips[k as keyof typeof dips]).toBeLessThan(0);
+      }
+    }
+  });
+});
+
+describe('isDisasterType / isDisasterSeverity', () => {
+  it('accepts each known type and rejects unknown / non-strings', () => {
+    for (const t of DISASTER_TYPES) expect(isDisasterType(t)).toBe(true);
+    expect(isDisasterType('tsunami')).toBe(false);
+    expect(isDisasterType('Earthquake')).toBe(false); // case-sensitive
+    expect(isDisasterType('')).toBe(false);
+    expect(isDisasterType(42)).toBe(false);
+    expect(isDisasterType(null)).toBe(false);
+    expect(isDisasterType(undefined)).toBe(false);
+  });
+
+  it('accepts each known severity and rejects unknown / non-strings', () => {
+    for (const s of DISASTER_SEVERITIES) expect(isDisasterSeverity(s)).toBe(true);
+    expect(isDisasterSeverity('extreme')).toBe(false);
+    expect(isDisasterSeverity('Minor')).toBe(false); // case-sensitive
+    expect(isDisasterSeverity('')).toBe(false);
+    expect(isDisasterSeverity(3)).toBe(false);
+    expect(isDisasterSeverity(undefined)).toBe(false);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// validateDisasterEvents
+// ---------------------------------------------------------------------------
+
+describe('validateDisasterEvents', () => {
+  const valid: DisasterEvent = { type: 'earthquake', target: 'uk', severity: 'severe' };
+
+  it('accepts the { events: [...] } shape', () => {
+    expect(validateDisasterEvents({ events: [valid] })).toEqual([valid]);
+  });
+
+  it('accepts a bare array (lenient about the wrapper)', () => {
+    expect(validateDisasterEvents([valid])).toEqual([valid]);
+  });
+
+  it('drops an event with an unknown type, keeping the valid one', () => {
+    const out = validateDisasterEvents({
+      events: [
+        { type: 'tsunami', target: 'uk', severity: 'minor' },
+        valid,
+      ],
+    });
+    expect(out).toEqual([valid]);
+  });
+
+  it('drops an event with a missing type', () => {
+    const out = validateDisasterEvents({
+      events: [{ target: 'uk', severity: 'minor' }, valid],
+    });
+    expect(out).toEqual([valid]);
+  });
+
+  it('drops an event with an unknown severity, keeping the valid one', () => {
+    const out = validateDisasterEvents({
+      events: [
+        { type: 'plague', target: 'uk', severity: 'extreme' },
+        valid,
+      ],
+    });
+    expect(out).toEqual([valid]);
+  });
+
+  it('drops an event with a missing severity', () => {
+    const out = validateDisasterEvents({
+      events: [{ type: 'plague', target: 'uk' }, valid],
+    });
+    expect(out).toEqual([valid]);
+  });
+
+  it('drops an event with an empty / whitespace target', () => {
+    const out = validateDisasterEvents({
+      events: [
+        { type: 'plague', target: '   ', severity: 'minor' },
+        { type: 'plague', target: '', severity: 'minor' },
+        valid,
+      ],
+    });
+    expect(out).toEqual([valid]);
+  });
+
+  it('caps a non-empty detail at 300 chars and keeps a short one', () => {
+    const long = 'x'.repeat(500);
+    const out = validateDisasterEvents({
+      events: [
+        { type: 'plague', target: 'uk', severity: 'minor', detail: long },
+        { type: 'flood', target: 'de', severity: 'minor', detail: 'a short note' },
+      ],
+    });
+    expect(out).toEqual([
+      { type: 'plague', target: 'uk', severity: 'minor', detail: 'x'.repeat(300) },
+      { type: 'flood', target: 'de', severity: 'minor', detail: 'a short note' },
+    ]);
+  });
+
+  it('omits the detail key entirely when detail is empty / missing', () => {
+    const out = validateDisasterEvents({
+      events: [
+        { type: 'flood', target: 'uk', severity: 'minor', detail: '' },
+        { type: 'flood', target: 'de', severity: 'minor' },
+      ],
+    });
+    expect(out).toEqual([
+      { type: 'flood', target: 'uk', severity: 'minor' },
+      { type: 'flood', target: 'de', severity: 'minor' },
+    ]);
+    expect(out[0]).not.toHaveProperty('detail');
+  });
+
+  it('drops non-object event entries', () => {
+    const out = validateDisasterEvents({ events: ['not-an-object', 7, null, valid] });
+    expect(out).toEqual([valid]);
+  });
+
+  it('yields { events: [] } (here, []) for a missing / malformed top-level value', () => {
+    expect(validateDisasterEvents(undefined)).toEqual([]);
+    expect(validateDisasterEvents(null)).toEqual([]);
+    expect(validateDisasterEvents('nope')).toEqual([]);
+    expect(validateDisasterEvents(5)).toEqual([]);
+    expect(validateDisasterEvents({})).toEqual([]);
+    expect(validateDisasterEvents({ events: 'not-an-array' })).toEqual([]);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// applyDisasterEvent — the deterministic dip
+// ---------------------------------------------------------------------------
+
+describe('applyDisasterEvent', () => {
+  it('a nation target: dips the nation AND every region it owns, then re-derives (identical values pass through)', () => {
+    // uk owns three identical regions; all stats identical → the re-derived
+    // aggregate equals the dipped values exactly.
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['g1', 'g2', 'g3']) },
+      { g1: RS(50, 50, 50, 50), g2: RS(50, 50, 50, 50), g3: RS(50, 50, 50, 50) },
+    );
+    applyDisasterEvent(state, { type: 'earthquake', target: 'uk', severity: 'moderate' });
+    // earthquake moderate = stability -4, economy -4 (military / population untouched)
+    expect(state.nations.uk.stats).toEqual(NS(50, 46, 46, 50));
+    for (const k of ['g1', 'g2', 'g3']) expect(state.regionStats[k]).toEqual(RS(50, 46, 46, 50));
+  });
+
+  it('a region target: dips ONLY the named region (the sibling region is untouched)', () => {
+    // uk owns g1 and g2 (identical). Target the region key g1 → only g1 dips.
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['g1', 'g2']) },
+      { g1: RS(50, 50, 50, 50), g2: RS(50, 50, 50, 50) },
+    );
+    applyDisasterEvent(state, { type: 'wildfire', target: 'g1', severity: 'severe' });
+    // wildfire severe = economy -7 only
+    expect(state.regionStats.g1).toEqual(RS(50, 43, 50, 50));
+    expect(state.regionStats.g2).toEqual(RS(50, 50, 50, 50)); // untouched
+    // re-derive (equal weights, min-biased median) → the nation takes the dipped value
+    expect(state.nations.uk.stats).toEqual(NS(50, 43, 50, 50));
+  });
+
+  it('a region target resolved by a validKeys-gated key hits its sole owner', () => {
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['g1']) },
+      { g1: RS(50, 50, 50, 50) },
+    );
+    applyDisasterEvent(
+      state,
+      { type: 'famine', target: 'g1', severity: 'moderate' },
+      undefined,
+      new Set(['g1']),
+    );
+    // famine moderate = economy -4, stability -4
+    expect(state.regionStats.g1).toEqual(RS(50, 46, 46, 50));
+    expect(state.nations.uk.stats).toEqual(NS(50, 46, 46, 50));
+  });
+
+  it('clamps every dip at 0 (never negative)', () => {
+    // low stability + military; a severe plague (stability -9, military -6) floors both.
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(3, 50, 3, 50), ['g1']) },
+      { g1: RS(3, 50, 3, 50) },
+    );
+    applyDisasterEvent(state, { type: 'plague', target: 'uk', severity: 'severe' });
+    expect(state.nations.uk.stats).toEqual(NS(0, 50, 0, 50));
+    expect(state.regionStats.g1).toEqual(RS(0, 50, 0, 50));
+  });
+
+  it('a 0-owner region is untargetable (the event is dropped, nothing dips)', () => {
+    // 'x1' is owned by nobody; no validKeys supplied, so the owners check drops it.
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['g1']) },
+      { g1: RS(50, 50, 50, 50) },
+    );
+    applyDisasterEvent(state, { type: 'plague', target: 'x1', severity: 'severe' });
+    expect(state.nations.uk.stats).toEqual(NS(50, 50, 50, 50)); // untouched
+    expect(state.regionStats.g1).toEqual(RS(50, 50, 50, 50));
+  });
+
+  it('a region with 2+ owners is untargetable (the event is dropped, neither dips)', () => {
+    // corrupt double-ownership of 'y1'
+    const state = mkState(
+      {
+        uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['y1']),
+        de: mkNation('de', 'DE', NS(60, 60, 60, 60), ['y1']),
+      },
+      { y1: RS(50, 50, 50, 50) },
+    );
+    applyDisasterEvent(state, { type: 'plague', target: 'y1', severity: 'severe' });
+    expect(state.nations.uk.stats).toEqual(NS(50, 50, 50, 50)); // untouched
+    expect(state.nations.de.stats).toEqual(NS(60, 60, 60, 60)); // untouched
+  });
+
+  it('an unknown region key (gated by validKeys) is dropped', () => {
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['g1']) },
+      { g1: RS(50, 50, 50, 50) },
+    );
+    // 'zzz' is not in the manifest → dropped before the owners check.
+    applyDisasterEvent(state, { type: 'plague', target: 'zzz', severity: 'severe' }, undefined, new Set(['g1']));
+    expect(state.nations.uk.stats).toEqual(NS(50, 50, 50, 50));
+  });
+
+  it('an unknown nation reference is dropped (no throw, no dip)', () => {
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['g1']) },
+      { g1: RS(50, 50, 50, 50) },
+    );
+    applyDisasterEvent(state, { type: 'plague', target: 'ghost', severity: 'severe' });
+    expect(state.nations.uk.stats).toEqual(NS(50, 50, 50, 50));
+    expect(state.regionStats.g1).toEqual(RS(50, 50, 50, 50));
+  });
+
+  it('an ambiguous nation reference (two share the name) is dropped', () => {
+    const state = mkState(
+      {
+        a: mkNation('a', 'Same', NS(50, 50, 50, 50), ['g1']),
+        b: mkNation('b', 'Same', NS(70, 70, 70, 70), ['d1']),
+      },
+      { g1: RS(50, 50, 50, 50), d1: RS(70, 70, 70, 70) },
+    );
+    applyDisasterEvent(state, { type: 'plague', target: 'Same', severity: 'severe' });
+    expect(state.nations.a.stats).toEqual(NS(50, 50, 50, 50)); // untouched
+    expect(state.nations.b.stats).toEqual(NS(70, 70, 70, 70)); // untouched
+  });
+
+  it('resolves a nation by (case-insensitive) name, not just id', () => {
+    const state = mkState(
+      { uk: mkNation('uk', 'United Kingdom', NS(50, 50, 50, 50), ['g1']) },
+      { g1: RS(50, 50, 50, 50) },
+    );
+    applyDisasterEvent(state, { type: 'epidemic', target: 'united kingdom', severity: 'moderate' });
+    // epidemic moderate = stability -4, military -2
+    expect(state.nations.uk.stats).toEqual(NS(48, 50, 46, 50));
+    expect(state.regionStats.g1).toEqual(RS(48, 50, 46, 50));
+  });
+
+  it('a 0-region nation keeps its directly-dipped stats (no re-derive to zero)', () => {
+    const iso = mkNation('iso', 'Iso', NS(50, 50, 50, 50), []);
+    const state = mkState({ iso }, {});
+    applyDisasterEvent(state, { type: 'epidemic', target: 'iso', severity: 'moderate' });
+    // epidemic moderate = stability -4, military -2 — the direct dip persists
+    expect(state.nations.iso.stats).toEqual(NS(48, 50, 46, 50));
+    expect(state.regionStats).toEqual({});
+  });
+
+  it('a region with no regionStats entry is skipped (the nation still dips + re-derives from its other regions)', () => {
+    // uk owns g1 (has stats) and g2 (no entry). Target the nation → the dip
+    // mirrors to g1 only (g2 has no entry to dip); re-derive uses g1 alone.
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['g1', 'g2']) },
+      { g1: RS(50, 50, 50, 50) },
+    );
+    applyDisasterEvent(state, { type: 'earthquake', target: 'uk', severity: 'moderate' });
+    expect(state.regionStats.g1).toEqual(RS(50, 46, 46, 50));
+    expect(state.regionStats).not.toHaveProperty('g2'); // never created
+    expect(state.nations.uk.stats).toEqual(NS(50, 46, 46, 50));
+  });
+});
+
+// ---------------------------------------------------------------------------
+// The Ability object
+// ---------------------------------------------------------------------------
+
+describe('disasters (Ability)', () => {
+  it('owns the "disasters" field and declares NO durable state fields (turn-transient)', () => {
+    expect(disasters.field).toBe('disasters');
+    expect(disasters.stateFields).toBeUndefined();
+  });
+
+  it('default() and stub() are fresh, empty { events: [] } values', () => {
+    expect(disasters.default()).toEqual({ events: [] });
+    expect(disasters.stub()).toEqual({ events: [] });
+    // fresh on every call (never a shared mutable reference)
+    expect(disasters.default()).not.toBe(disasters.default());
+    expect(disasters.default().events).not.toBe(disasters.default().events);
+    expect(disasters.stub()).not.toBe(disasters.stub());
+  });
+
+  it('isMeaningful is true iff there is at least one event', () => {
+    expect(disasters.isMeaningful({ events: [] })).toBe(false);
+    expect(disasters.isMeaningful({ events: [{ type: 'plague', target: 'uk', severity: 'minor' }] })).toBe(
+      true,
+    );
+  });
+
+  it('payload() is always empty (the layer is turn-transient)', () => {
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['g1']) },
+      { g1: RS(50, 50, 50, 50) },
+    );
+    expect(disasters.payload({ state })).toEqual({});
+  });
+
+  it('validate() wraps the low-level validator into the { events } field shape', () => {
+    const valid = { type: 'flood', target: 'uk', severity: 'minor' } as DisasterEvent;
+    expect(disasters.validate({ events: [valid] })).toEqual({ events: [valid] });
+    expect(disasters.validate(undefined)).toEqual({ events: [] });
+    expect(disasters.validate([valid])).toEqual({ events: [valid] }); // bare array leniency
+  });
+
+  it('apply() wires ctx.geoOf + ctx.validRegionKeys through to the dip', () => {
+    const state = mkState(
+      { uk: mkNation('uk', 'UK', NS(50, 50, 50, 50), ['g1']) },
+      { g1: RS(50, 50, 50, 50) },
+    );
+    const ctx = mkCtx(state, new Set(['g1']));
+    const data: DisastersOps = { events: [{ type: 'volcanic', target: 'g1', severity: 'moderate' }] };
+    disasters.apply(state, data, ctx);
+    // volcanic moderate = economy -4, stability -3
+    expect(state.regionStats.g1).toEqual(RS(50, 46, 47, 50));
+    expect(state.nations.uk.stats).toEqual(NS(50, 46, 47, 50));
+  });
+});
@@ -0,0 +1,259 @@
+// The DISASTERS & PANDEMICS ability (v0.41.0, #63) as a modular LLM-ability
+// (v0.40.0, #67). Natural and man-made catastrophes — earthquakes, floods,
+// volcanic eruptions, wildfires, famines, plagues, and epidemics — hit a
+// nation or a single region each turn. Unlike most other abilities this one
+// is **turn-transient**: it owns NO `GameState` field (no durable list, no
+// `db.ts` change) — exactly like the hybrid layer. Each event carries a
+// `type` and a `severity`, and the engine applies a DETERMINISTIC stat dip
+// chosen from the `(type, severity)` lookup table below (no hidden
+// randomness — the LLM chooses the type and severity, the table decides the
+// magnitude). The dip lands on the target nation's `stats` (clamped 0–100)
+// AND on the target's regions (`regionStats` — the single named region when
+// the target was a region key, otherwise every region the target owns), and
+// the target's derived `stats` are re-derived afterwards (the same 0-region /
+// no-entry guards as hybrid / economy / industry, so a 0-region nation keeps
+// its directly-mutated value and the dip persists to the next turn). The
+// target is a nation (resolved by the shared `resolveNationRef`) or a region
+// key (which hits its SOLE owner); a key with 0 or 2+ owners is untargetable.
+// There is no acting-nation (`from`) field on a disaster — a catastrophe is
+// not an attack, so the hybrid's self-target drop does not apply. Malformed
+// events and unresolvable targets are dropped, never thrown.
+
+import { clampStat, deriveNationStats } from '../../shared/protocol';
+import type {
+  DisasterEvent,
+  DisasterSeverity,
+  DisasterType,
+} from '../../shared/protocol';
+import type { GameState, Nation, NationStats, StatKey } from '../../shared/types';
+import { resolveNationRef, str } from './shared';
+import type { Ability } from './types';
+
+/** The seven disaster types a turn can declare (v0.41.0, #63). */
+export const DISASTER_TYPES: readonly DisasterType[] = [
+  'earthquake',
+  'flood',
+  'volcanic',
+  'wildfire',
+  'famine',
+  'plague',
+  'epidemic',
+];
+
+/** The three severity levels a disaster event can carry (v0.41.0, #63). */
+export const DISASTER_SEVERITIES: readonly DisasterSeverity[] = ['minor', 'moderate', 'severe'];
+
+const VALID_DISASTER_TYPES = new Set<string>(DISASTER_TYPES);
+const VALID_SEVERITIES = new Set<string>(DISASTER_SEVERITIES);
+
+/** True when `t` is one of the seven known disaster types (v0.41.0, #63). */
+export function isDisasterType(t: unknown): t is DisasterType {
+  return typeof t === 'string' && VALID_DISASTER_TYPES.has(t);
+}
+
+/** True when `s` is one of the three known disaster severities (v0.41.0, #63). */
+export function isDisasterSeverity(s: unknown): s is DisasterSeverity {
+  return typeof s === 'string' && VALID_SEVERITIES.has(s);
+}
+
+/**
+ * (v0.41.0, #63) The DETERMINISTIC per-`(type, severity)` stat dip of a
+ * disaster event. Each pair maps to a small set of signed (negative) stat
+ * deltas: no hidden randomness — the LLM picks the type and severity, the
+ * table decides the magnitude. Population is never touched (a disaster hurts
+ * military / economy / stability, never the head-count). Every (type,
+ * severity) combination dips at least one stat (none is purely
+ * informational).
+ */
+export const DISASTER_EFFECTS: Record<DisasterType, Record<DisasterSeverity, Partial<Record<StatKey, number>>>> = {
+  earthquake: {
+    minor: { stability: -2, economy: -2 },
+    moderate: { stability: -4, economy: -4 },
+    severe: { stability: -7, economy: -7 },
+  },
+  flood: {
+    minor: { economy: -2, stability: -1 },
+    moderate: { economy: -3, stability: -2 },
+    severe: { economy: -6, stability: -4 },
+  },
+  volcanic: {
+    minor: { economy: -2, stability: -2 },
+    moderate: { economy: -4, stability: -3 },
+    severe: { economy: -7, stability: -6 },
+  },
+  wildfire: {
+    minor: { economy: -2 },
+    moderate: { economy: -4 },
+    severe: { economy: -7 },
+  },
+  famine: {
+    minor: { economy: -2, stability: -2 },
+    moderate: { economy: -4, stability: -4 },
+    severe: { economy: -7, stability: -7 },
+  },
+  plague: {
+    minor: { stability: -3, military: -2 },
+    moderate: { stability: -5, military: -3 },
+    severe: { stability: -9, military: -6 },
+  },
+  epidemic: {
+    minor: { stability: -2, military: -1 },
+    moderate: { stability: -4, military: -2 },
+    severe: { stability: -7, military: -4 },
+  },
+};
+
+/**
+ * (v0.41.0, #63) Validate the raw `disasters` field of a turn into a safe
+ * list of {@link DisasterEvent}s. Defensive like the rest of the parser — never throws.
+ * The raw value may be the object `{ events: [...] }` (the TurnResult shape)
+ * or a bare array (be lenient about either). Each event needs a known `type`
+ * (one of {@link DISASTER_TYPES}), a known `severity` (one of
+ * {@link DISASTER_SEVERITIES}), and a non-empty `target` (a nation id/name or
+ * a region key, capped at 200 chars); a non-empty `detail` is capped at 300
+ * chars. An event with an unknown / missing `type`, an unknown / missing
+ * `severity`, or an empty `target` is dropped. Resolution of `target` to a
+ * concrete nation (or a region's sole owner) happens at apply time
+ * (`applyDisasterEvent`), not here. A missing / malformed top-level value
+ * yields `{ events: [] }`.
+ */
+export function validateDisasterEvents(raw: unknown): DisasterEvent[] {
+  let list: unknown[] | null = null;
+  if (Array.isArray(raw)) {
+    list = raw;
+  } else if (raw && typeof raw === 'object') {
+    const inner = (raw as Record<string, unknown>).events;
+    if (Array.isArray(inner)) list = inner;
+  }
+  if (!list) return [];
+  const out: DisasterEvent[] = [];
+  for (const e of list) {
+    if (!e || typeof e !== 'object') continue;
+    const o = e as Record<string, unknown>;
+    if (!isDisasterType(o.type)) continue; // unknown / missing type: drop
+    if (!isDisasterSeverity(o.severity)) continue; // unknown / missing severity: drop
+    const target = str(o.target, 200);
+    if (!target) continue; // empty / missing target: drop
+    const detail = str(o.detail, 300);
+    out.push({
+      type: o.type,
+      target,
+      severity: o.severity,
+      ...(detail ? { detail } : {}),
+    });
+  }
+  return out;
+}
+
+/**
+ * (v0.41.0, #63) Resolve a disaster event's `target` (a nation id/name OR a
+ * region key) to the concrete nation it affects. A nation ref resolves via
+ * {@link resolveNationRef}; a region key resolves to its SOLE owner (a region
+ * with zero or 2+ owners can't be a valid target). Returns the affected
+ * nation plus the specific region key (when the target was a region) so the
+ * dip can land on just that region's entry. `validKeys` (when supplied)
+ * gates the region-key path; a ref that is neither a known nation nor a
+ * valid region key returns `null`. Pure; never throws.
+ *
+ * NOTE: there is no acting-nation (`from`) field on a disaster — a
+ * catastrophe is not an attack, so (unlike the hybrid layer) a self-target
+ * drop does NOT apply: an earthquake can hit the nation it is declared
+ * against.
+ */
+function resolveDisasterTarget(
+  state: GameState,
+  target: string,
+  validKeys?: ReadonlySet<string>,
+): { nation: Nation; regionKey?: string } | null {
+  const id = resolveNationRef(state, target);
+  if (id !== null) {
+    const n = state.nations[id];
+    return n ? { nation: n } : null;
+  }
+  const key = (target ?? '').trim();
+  if (!key) return null;
+  if (validKeys && !validKeys.has(key)) return null; // unknown region key
+  const owners = Object.values(state.nations).filter((n) => n.territory.includes(key));
+  if (owners.length !== 1) return null; // 0 or 2+ owners: not a targetable region
+  return { nation: owners[0], regionKey: key };
+}
+
+/** Apply each signed dip in `dips` to a stats record in place (clamped). */
+function applyDips(stats: NationStats, dips: Partial<Record<StatKey, number>>): void {
+  (Object.keys(dips) as StatKey[]).forEach((k) => {
+    const d = dips[k];
+    if (typeof d === 'number') stats[k] = clampStat(stats[k] + d);
+  });
+}
+
+/**
+ * (v0.41.0, #63) Apply ONE disaster event to the (cloned) `next` state,
+ * mutating it in place and never throwing. Resolution order:
+ *   1. `target` must resolve to a concrete nation (a nation ref, or a region
+ *      key's sole owner); an unresolvable target (unknown / ambiguous ref, a
+ *      region with 0 or 2+ owners, or an unknown region key) drops the event.
+ * Then the deterministic `(type, severity)` dip from {@link DISASTER_EFFECTS}
+ * is applied:
+ *   - the target nation's `stats` is dipped on each affected stat (clamped
+ *     0–100);
+ *   - the dip is mirrored to the target's regions — the single named region
+ *     when the target was a region key, otherwise every region the target
+ *     owns (regions with no `regionStats` entry are skipped);
+ *   - the target nation's derived `stats` are re-derived afterwards (the
+ *     same 0-region / no-entry guards as the main recompute, so a 0-region
+ *     nation keeps its directly-mutated value and a dip persists).
+ * A disaster never moves territory (sole ownership is untouched) and never
+ * touches `population`.
+ */
+export function applyDisasterEvent(
+  next: GameState,
+  ev: DisasterEvent,
+  geoOf?: (key: string) => { area: number; population: number } | undefined,
+  validKeys?: ReadonlySet<string>,
+): void {
+  const target = resolveDisasterTarget(next, ev.target, validKeys);
+  if (target === null) return; // unresolvable target: drop
+  const dips = DISASTER_EFFECTS[ev.type][ev.severity];
+  if (!dips) return; // defensive: unknown (type, severity) pair
+  applyDips(target.nation.stats, dips);
+  if (target.regionKey !== undefined) {
+    const rs = next.regionStats[target.regionKey];
+    if (rs) applyDips(rs, dips);
+  } else {
+    for (const key of target.nation.territory) {
+      const rs = next.regionStats[key];
+      if (!rs) continue; // a key with no entry is skipped
+      applyDips(rs, dips);
+    }
+  }
+  // Re-derive the target nation's aggregate stats so the dip persists (the
+  // main recompute ran earlier this turn; without this the dip would be
+  // washed out next turn). Same 0-region / no-entry guards as hybrid /
+  // economy: a nation with no region stats entry keeps its directly-mutated
+  // `stats`.
+  if (target.nation.territory.length > 0 && target.nation.territory.some((k) => next.regionStats[k])) {
+    target.nation.stats = deriveNationStats(target.nation.territory, next.regionStats, geoOf);
+  }
+}
+
+export const disasters: Ability<'disasters'> = {
+  field: 'disasters',
+  default: () => ({ events: [] }),
+  // The low-level validator returns a bare list; the field's shape is the
+  // `{ events }` object (mirrors the historical TurnResult shape).
+  validate: (raw) => ({ events: validateDisasterEvents(raw) }),
+  apply: (state, data, ctx) => {
+    for (const ev of data.events) {
+      applyDisasterEvent(state, ev, ctx.geoOf, ctx.validRegionKeys);
+    }
+  },
+  schemaLine: () =>
+    '  "disasters": {"events":[{"type":"<earthquake|flood|volcanic|wildfire|famine|plague|epidemic>","target":"<nation id or name, or region key>","severity":"<minor|moderate|severe>","detail":"<short detail>"}]},',
+  constraint: () =>
+    '- Disasters & pandemics ("disasters.events") are natural and man-made catastrophes — earthquakes, floods, volcanic eruptions, wildfires, famines, plagues, and epidemics — that hit a nation or a single region this turn. Each event names a "target" (a nation id / name, or a region key that hits that region\'s SOLE owner — a region with 0 or 2+ owners can\'t be hit) and a "severity" (minor / moderate / severe); the engine applies a small, DETERMINISTIC stat dip from the (type, severity) table (a severe plague is the hardest hit; none of them touch population, and none move borders — sole ownership is untouched). There is NO memory of past disasters (the layer is turn-transient): a plague or epidemic that persists is simply RE-DECLARED each turn it continues, with a fresh "severity". Propose at most 1-2 events per turn and narrate each one in "events" (a "disaster" event).',
+  isMeaningful: (data) => data.events.length > 0,
+  stub: () => ({ events: [] }),
+  // The layer is turn-transient — it contributes nothing to the user payload
+  // (no durable state to show the model), so the payload is always empty.
+  payload: () => ({}),
+};
@@ -39,6 +39,7 @@ Respond with ONLY a valid JSON object of exactly this shape. No prose, no commen
  "nuclear": {"arm":["<nation id or name>"],"strikes":[{"from":"<nuclear-capable nation id or name>","target":"<nation id or name, or region key>"}]},
  "leaders": {"changes":[{"target":"<nation id or name>","name":"<new leader name>","cause":"<assassination|death|appointed>"}]},
  "ideology": {"changes":[{"target":"<nation id or name>","to":"<new form of government>"}]},
+  "disasters": {"events":[{"type":"<earthquake|flood|volcanic|wildfire|famine|plague|epidemic>","target":"<nation id or name, or region key>","severity":"<minor|moderate|severe>","detail":"<short detail>"}]},
  "markers": {"add":[{"type":"<city|factory|army|port|capital|fleet|rocket|gathering>","name":"<short name>","regionKey":"<region key>"}],"remove":["<marker id>"]}
 }

@@ -64,6 +65,7 @@ HARD CONSTRAINTS
 - Nuclear / WMD ("nuclear"): a nation is "nuclear-capable" when its "nuclear" flag is true or it currently owns a "rocket" marker. "arm" names (by id or name) nations to grant the "nuclear" flag — idempotent (already-armed nations are unchanged); a newly armed nation is capable this same turn. "strikes" is a list of "NuclearStrike" objects, each "{from, target}" — "from" is the striking nation (must be nuclear-capable and never itself) and "target" is either a nation (its nation collapses: economy -40, military -50, stability -40; every active war the target fights ends by capitulation and the "war" relations it caused downgrade to "hostile") or a region key (that region is released to no man's land, its regionStats entry deleted, and its sole owner collapses the same way — a region with 0 or 2+ owners, or one the striker itself owns, is dropped). If the struck nation (or the struck region's owner) is itself nuclear-capable, a "MAD" retaliation is applied: it strikes the striker back for half the collapse, and the two nations' relations are forced to "hostile". At most one strike per turn; always narrate a strike (and a retaliation, if any) in "events".
 - Leaders ("leaders") name each nation's current head of state and change it. Each change is {"target":"<nation id or name>","name":"<new leader name>","cause":"<assassination|death|appointed>"}: "assassination" kills the current leader (a dramatic, destabilizing blow — a −15 stability dip, a "military" event) and is only valid when the target already has a leader; "death" is a natural-causes succession (a quieter −3 dip, a "political" event), also only valid for a nation that has a leader; "appointed" sets (or creates) a leader and is always valid (a neutral 0 effect, a "political" event). Propose at most 1-2 changes per turn and narrate each one in "events". This is the HEAVY leader lever — use the lighter "hybrid" {"type":"assassinate"} op (a −5 stability dip, no leader replacement) for a mere hit on a leader or region without changing who is in charge. The user message's "nations" field lists each nation's current "leader" (omitted when a nation has none).
 - Ideology ("ideology") is each nation's form of government — a free-form label such as "democracy", "fascism", or "military junta" — that can shift through a coup, a revolution, a reform, or a constitutional change. Each change is {"target":"<nation id or name>","to":"<new form of government>"}: the engine sets the nation's ideology, applies a small, deterministic stability dip (−5 — a regime shift always unsettles a nation), and narrates it with a "political" event. It is a third axis, distinct from a takeover (which RENAMES the nation) and from a leader change (who is in charge): the nation keeps its id, name, territory, relations, and leader — only its form of government and its stability move. Similar forms of government are a SOFT, prompt-level compatibility nudge only (nations with alike ideologies tend to ally and trade; very opposed ones tend to clash) — there is no engine gate behind it. Propose at most 1-2 changes per turn and narrate each one in "events". The user message's "nations" field lists each nation's current "ideology" (omitted when a nation has none).
+- Disasters & pandemics ("disasters.events") are natural and man-made catastrophes — earthquakes, floods, volcanic eruptions, wildfires, famines, plagues, and epidemics — that hit a nation or a single region this turn. Each event names a "target" (a nation id / name, or a region key that hits that region's SOLE owner — a region with 0 or 2+ owners can't be hit) and a "severity" (minor / moderate / severe); the engine applies a small, DETERMINISTIC stat dip from the (type, severity) table (a severe plague is the hardest hit; none of them touch population, and none move borders — sole ownership is untouched). There is NO memory of past disasters (the layer is turn-transient): a plague or epidemic that persists is simply RE-DECLARED each turn it continues, with a fresh "severity". Propose at most 1-2 events per turn and narrate each one in "events" (a "disaster" event).
 - Prefer 1-4 events per turn; keep each text 1-3 sentences.
 - Keep your internal reasoning brief (a few sentences) and go straight to the JSON result; do not over-deliberate or re-derive facts already present in the state.
 - Keep every stat value between 0 and 100.
@@ -39,6 +39,7 @@ You have a getNeighbours tool: given region keys it returns the region keys that
  "nuclear": {"arm":["<nation id or name>"],"strikes":[{"from":"<nuclear-capable nation id or name>","target":"<nation id or name, or region key>"}]},
  "leaders": {"changes":[{"target":"<nation id or name>","name":"<new leader name>","cause":"<assassination|death|appointed>"}]},
  "ideology": {"changes":[{"target":"<nation id or name>","to":"<new form of government>"}]},
+  "disasters": {"events":[{"type":"<earthquake|flood|volcanic|wildfire|famine|plague|epidemic>","target":"<nation id or name, or region key>","severity":"<minor|moderate|severe>","detail":"<short detail>"}]},
  "markers": {"add":[{"type":"<city|factory|army|port|capital|fleet|rocket|gathering>","name":"<short name>","regionKey":"<region key>"}],"remove":["<marker id>"]}
 }

@@ -64,6 +65,7 @@ HARD CONSTRAINTS
 - Nuclear / WMD ("nuclear"): a nation is "nuclear-capable" when its "nuclear" flag is true or it currently owns a "rocket" marker. "arm" names (by id or name) nations to grant the "nuclear" flag — idempotent (already-armed nations are unchanged); a newly armed nation is capable this same turn. "strikes" is a list of "NuclearStrike" objects, each "{from, target}" — "from" is the striking nation (must be nuclear-capable and never itself) and "target" is either a nation (its nation collapses: economy -40, military -50, stability -40; every active war the target fights ends by capitulation and the "war" relations it caused downgrade to "hostile") or a region key (that region is released to no man's land, its regionStats entry deleted, and its sole owner collapses the same way — a region with 0 or 2+ owners, or one the striker itself owns, is dropped). If the struck nation (or the struck region's owner) is itself nuclear-capable, a "MAD" retaliation is applied: it strikes the striker back for half the collapse, and the two nations' relations are forced to "hostile". At most one strike per turn; always narrate a strike (and a retaliation, if any) in "events".
 - Leaders ("leaders") name each nation's current head of state and change it. Each change is {"target":"<nation id or name>","name":"<new leader name>","cause":"<assassination|death|appointed>"}: "assassination" kills the current leader (a dramatic, destabilizing blow — a −15 stability dip, a "military" event) and is only valid when the target already has a leader; "death" is a natural-causes succession (a quieter −3 dip, a "political" event), also only valid for a nation that has a leader; "appointed" sets (or creates) a leader and is always valid (a neutral 0 effect, a "political" event). Propose at most 1-2 changes per turn and narrate each one in "events". This is the HEAVY leader lever — use the lighter "hybrid" {"type":"assassinate"} op (a −5 stability dip, no leader replacement) for a mere hit on a leader or region without changing who is in charge. The user message's "nations" field lists each nation's current "leader" (omitted when a nation has none).
 - Ideology ("ideology") is each nation's form of government — a free-form label such as "democracy", "fascism", or "military junta" — that can shift through a coup, a revolution, a reform, or a constitutional change. Each change is {"target":"<nation id or name>","to":"<new form of government>"}: the engine sets the nation's ideology, applies a small, deterministic stability dip (−5 — a regime shift always unsettles a nation), and narrates it with a "political" event. It is a third axis, distinct from a takeover (which RENAMES the nation) and from a leader change (who is in charge): the nation keeps its id, name, territory, relations, and leader — only its form of government and its stability move. Similar forms of government are a SOFT, prompt-level compatibility nudge only (nations with alike ideologies tend to ally and trade; very opposed ones tend to clash) — there is no engine gate behind it. Propose at most 1-2 changes per turn and narrate each one in "events". The user message's "nations" field lists each nation's current "ideology" (omitted when a nation has none).
+- Disasters & pandemics ("disasters.events") are natural and man-made catastrophes — earthquakes, floods, volcanic eruptions, wildfires, famines, plagues, and epidemics — that hit a nation or a single region this turn. Each event names a "target" (a nation id / name, or a region key that hits that region's SOLE owner — a region with 0 or 2+ owners can't be hit) and a "severity" (minor / moderate / severe); the engine applies a small, DETERMINISTIC stat dip from the (type, severity) table (a severe plague is the hardest hit; none of them touch population, and none move borders — sole ownership is untouched). There is NO memory of past disasters (the layer is turn-transient): a plague or epidemic that persists is simply RE-DECLARED each turn it continues, with a fresh "severity". Propose at most 1-2 events per turn and narrate each one in "events" (a "disaster" event).
 - Prefer 1-4 events per turn; keep each text 1-3 sentences.
 - Keep your internal reasoning brief (a few sentences) and go straight to the JSON result; do not over-deliberate or re-derive facts already present in the state.
 - Keep every stat value between 0 and 100.
@@ -1,8 +1,8 @@
 // The ordered LLM-ability registry.
 //
-// `ABILITIES` is the single source of truth for the 8 per-feature LLM abilities.
+// `ABILITIES` is the single source of truth for the 9 per-feature LLM abilities.
 // The engine iterates it in this order:
-//   takeovers → wars → hybrid → economy → industry → nuclear → leaders → ideology
+//   takeovers → wars → hybrid → economy → industry → nuclear → leaders → ideology → disasters
 // for (a) the system-prompt schema lines + constraint bullets, (b) the per-ability
 // validate calls inside validateTurnResult, (c) the payload fields in buildUserPrompt,
 // (d) the ordered apply block inside applyTurnResult, (e) the isMeaningful check,
@@ -22,10 +22,11 @@ import { industry } from './industry';
 import { nuclear } from './nuclear';
 import { leaders } from './leaders';
 import { ideology } from './ideology';
+import { disasters } from './disasters';
 import type { Ability, AbilityField } from './types';

 /**
- * The 8 per-feature LLM abilities in their canonical apply order.
+ * The 9 per-feature LLM abilities in their canonical apply order.
 * The order matters: it determines the order of the schema lines in the
 * system prompt, the order of the validate calls, the order of the apply
 * steps, and the order of the payload fields in the user prompt.
@@ -39,6 +40,7 @@ export const ABILITIES: readonly Ability<AbilityField>[] = [
  nuclear,
  leaders,
  ideology,
+  disasters,
 ];

 // ── type re-exports ────────────────────────────────────────────────────────────
@@ -125,3 +127,15 @@ export {
 export {
  validateIdeologyOps,
 } from './ideology';
+
+// ── disasters ────────────────────────────────────────────────────────────────
+
+export {
+  validateDisasterEvents,
+  applyDisasterEvent,
+  isDisasterType,
+  isDisasterSeverity,
+  DISASTER_TYPES,
+  DISASTER_SEVERITIES,
+  DISASTER_EFFECTS,
+} from './disasters';
@@ -3,13 +3,16 @@
 // These tests pin the refactor's two load-bearing guarantees:
 //
 //   1. GOLDEN PROMPTS — the system prompt (both tool variants) and the user
-//      prompt the refactored engine builds are BYTE-IDENTICAL to the committed
-//      golden fixtures in ./goldens/ (captured in P1 from the pre-refactor
-//      engine). Any transcription drift in an ability's schemaLine /
-//      constraint / payload is caught here.
+//      prompt the engine builds are BYTE-IDENTICAL to the committed golden
+//      fixtures in ./goldens/ (captured in P1 from the pre-refactor engine, and
+//      re-baselined when a feature INTENTIONALLY changes the prompt — e.g. the
+//      system goldens were regenerated in v0.41.0 when the disasters ability
+//      was added). Any transcription drift in an ability's schemaLine /
+//      constraint / payload is caught here. The USER prompt golden is unchanged
+//      by the disasters feature (its payload is always empty).
 //
 //   2. REGISTRY CONTRACT — the ABILITIES registry is the canonical ordered
-//      list of the 8 abilities; each ability's default() equals the canonical
+//      list of the 9 abilities; each ability's default() equals the canonical
 //      TurnResult default for its field, is a FRESH value (never a shared
 //      reference), its default is not "meaningful" while a populated value is,
 //      and the registry composes (a hypothetical extra ability can be appended
@@ -26,13 +29,19 @@ import { fileURLToPath } from 'node:url';
 import { describe, expect, it } from 'vitest';
 import {
  activeWarPairs,
+  applyDisasterEvent,
  applyIndustryEffects,
  atWar,
  buildSystemPrompt,
  buildUserPrompt,
+  DISASTER_EFFECTS,
+  DISASTER_SEVERITIES,
+  DISASTER_TYPES,
  freshNationId,
  freshWarId,
  HYBRID_STAT_EFFECT,
+  isDisasterSeverity,
+  isDisasterType,
  isHybridOpType,
  isIndustryType,
  NEW_NATION_STATS,
@@ -40,6 +49,7 @@ import {
  resolveRegionKey,
  shiftRelationTowardHostile,
  syncWarRelations,
+  validateDisasterEvents,
  validateEconomyOps,
  validateHybridOps,
  validateIdeologyOps,
@@ -206,6 +216,7 @@ function fullDefaultTurn(): TurnResult {
    nuclear: { arm: [], strikes: [] },
    leaders: { changes: [] },
    ideology: { changes: [] },
+    disasters: { events: [] },
    markers: { add: [], remove: [] },
  };
 }
@@ -229,11 +240,13 @@ function meaningfulFor(field: AbilityField): TurnResult[AbilityField] {
      return { changes: [{ target: 'a1', name: 'New Alpha Leader', cause: 'appointed' }] };
    case 'ideology':
      return { changes: [{ target: 'a1', to: 'democracy' }] };
+    case 'disasters':
+      return { events: [{ type: 'earthquake', target: 'a1', severity: 'minor' }] };
  }
 }

 describe('ABILITIES registry (v0.40.0, #67)', () => {
-  it('is the canonical 8-ability order (takeovers → ideology)', () => {
+  it('is the canonical 9-ability order (takeovers → disasters)', () => {
    expect(ABILITIES.map((a) => a.field)).toEqual([
      'takeovers',
      'wars',
@@ -243,13 +256,14 @@ describe('ABILITIES registry (v0.40.0, #67)', () => {
      'nuclear',
      'leaders',
      'ideology',
+      'disasters',
    ]);
  });

-  it('lists 8 distinct fields, each a key of TurnResult', () => {
+  it('lists 9 distinct fields, each a key of TurnResult', () => {
    const fields = ABILITIES.map((a) => a.field);
-    expect(fields).toHaveLength(8);
-    expect(new Set(fields).size).toBe(8);
+    expect(fields).toHaveLength(9);
+    expect(new Set(fields).size).toBe(9);
    const all = fullDefaultTurn();
    for (const f of fields) expect(f in all).toBe(true);
  });
@@ -314,7 +328,7 @@ describe('ABILITIES registry (v0.40.0, #67)', () => {
  it('composes: a hypothetical extra ability can be appended and every uniform loop still runs', () => {
    // The registry is a plain ordered array the engine iterates uniformly. A
    // structural (field-name-agnostic) loop over the abilities — schema line,
-    // constraint bullet — must keep working when a 9th ability is appended.
+    // constraint bullet — must keep working when a 10th ability is appended.
    // This documents the extension point without widening the closed
    // AbilityField union.
    interface Loopable {
@@ -333,9 +347,9 @@ describe('ABILITIES registry (v0.40.0, #67)', () => {
      'custom',
    ]);
    // every uniform loop runs over all N abilities, the appended one included:
-    expect(extended.map((a) => a.schemaLine())).toHaveLength(9);
-    expect(extended.map((a) => a.constraint())).toHaveLength(9);
-    expect(extended[8].schemaLine()).toBe('  "custom": [],');
+    expect(extended.map((a) => a.schemaLine())).toHaveLength(10);
+    expect(extended.map((a) => a.constraint())).toHaveLength(10);
+    expect(extended[9].schemaLine()).toBe('  "custom": [],');
  });

  it('the engine still re-exports every name its callers import from it', () => {
@@ -366,6 +380,14 @@ describe('ABILITIES registry (v0.40.0, #67)', () => {
      validateTakeovers,
      validateWarOps,
      applyIndustryEffects,
+      // disasters (v0.41.0, #63)
+      validateDisasterEvents,
+      applyDisasterEvent,
+      isDisasterType,
+      isDisasterSeverity,
+      DISASTER_TYPES,
+      DISASTER_SEVERITIES,
+      DISASTER_EFFECTS,
    };
    for (const [name, value] of Object.entries(reexported)) {
      expect(value, `engine should re-export ${name}`).toBeDefined();
@@ -17,11 +17,11 @@ import type {
 import type { MarkerInfo, TurnResult, WarInfo } from '../../shared/protocol';

 /**
- * The 8 per-feature LLM abilities a turn can exercise, by the `TurnResult`
+ * The 9 per-feature LLM abilities a turn can exercise, by the `TurnResult`
 * field each one owns. This is the closed universe the ordered `ABILITIES`
 * registry (./index.ts) is built from: a turn's world changes are exactly the
 * core engine effects (events / stats / territory / no-man's-land / nation-ops
- * / markers) plus, in order, these eight abilities.
+ * / markers) plus, in order, these nine abilities.
 */
 export type AbilityField =
  | 'takeovers'
@@ -31,7 +31,8 @@ export type AbilityField =
  | 'industry'
  | 'nuclear'
  | 'leaders'
-  | 'ideology';
+  | 'ideology'
+  | 'disasters';

 /**
 * Everything a single ability's `apply` may need from the surrounding turn.
@@ -64,7 +65,7 @@ export interface AbilityCtx {
  readonly centroidOf?: (key: string) => { lat: number; lon: number; spread: number } | undefined;
  /**
   * The `getNeighbours` tool executor (verify land borders). Available to an
-   * ability that needs it; none of the current eight use it (it drives the
+   * ability that needs it; none of the current nine use it (it drives the
   * core territory/conquest logic), but the type is here so a future one can.
   */
  readonly getNeighbours?: (regionKeys: string[]) => string[];
@@ -151,7 +152,7 @@ export interface Ability<K extends AbilityField = AbilityField> {
   * The `GameState` fields this ability owns and that must be defaulted on a
   * legacy SQLite row (db.ts migration, only-if-undefined). `undefined` for
   * abilities that add no durable state (takeovers, hybrid, nuclear, leaders,
-   * ideology).
+   * ideology, disasters).
   */
  readonly stateFields?: readonly string[];

@@ -570,7 +570,7 @@ describe('validateNationOps (v0.23 #16 P4a)', () => {
      relations: [],
      territoryChanges: [],
      unowned: [],
-      nationOps: [{ kind: 'rename', nationRef: 'France', to: 'French Republic' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+      nationOps: [{ kind: 'rename', nationRef: 'France', to: 'French Republic' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    });
    expect(withOps).not.toBeNull();
    expect(withOps!.nationOps).toEqual([{ kind: 'rename', nationRef: 'France', to: 'French Republic' }]);
@@ -592,7 +592,7 @@ describe('applyTurnResult (nation-op proposals, v0.23 #16 P4a)', () => {
      relations: [],
      territoryChanges: [],
      unowned: [],
-      nationOps: [{ kind: 'rename', nationRef: 'de', to: 'Reich' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+      nationOps: [{ kind: 'rename', nationRef: 'de', to: 'Reich' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    });
    expect(next.nations.de.name).toBe('DE'); // still the old name
    expect(next.pendingNationOps).toEqual([{ kind: 'rename', nationRef: 'de', to: 'Reich' }]);
@@ -613,7 +613,7 @@ describe('applyTurnResult (nation-op proposals, v0.23 #16 P4a)', () => {
      relations: [],
      territoryChanges: [],
      unowned: [],
-      nationOps: [{ kind: 'rename', nationRef: 'us', to: 'USA' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] }, // new proposal this turn
+      nationOps: [{ kind: 'rename', nationRef: 'us', to: 'USA' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] }, // new proposal this turn
    });
    expect(next.pendingNationOps).toEqual([
      { kind: 'rename', nationRef: 'de', to: 'Reich' }, // the old one survived
@@ -632,7 +632,7 @@ describe('applyTurnResult (nation-op proposals, v0.23 #16 P4a)', () => {
      relations: [],
      territoryChanges: [],
      unowned: [],
-      nationOps: [{ kind: 'rename', nationRef: 'de', to: 'Reich' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+      nationOps: [{ kind: 'rename', nationRef: 'de', to: 'Reich' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    });
    expect(next.pendingNationOps).toEqual([{ kind: 'rename', nationRef: 'de', to: 'Reich' }]);
  });
@@ -1089,7 +1089,7 @@ describe('applyTurnResult', () => {
      relations: [],
      territoryChanges: [],
      unowned: [],
-      nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+      nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    applyTurnResult(state, result);
    expect(JSON.stringify(state)).toBe(snapshot);
@@ -1106,7 +1106,7 @@ describe('applyTurnResult', () => {
      relations: [],
      territoryChanges: [],
      unowned: [],
-      nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+      nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result);
    expect(next.pending).toEqual([]);
@@ -1129,7 +1129,7 @@ describe('applyTurnResult', () => {
      // is not a real key at all. Both are proposed as a gain by DE.
      territoryChanges: [{ nation: 'de', gain: ['wales-bbbb', 'not-a-region-xyz'], lose: [] }],
      unowned: [],
-      nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+      nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result, new Set(['wales-bbbb']));
    // the valid key was gained (taken from its sole previous owner); the bogus one was ignored
@@ -1155,7 +1155,7 @@ describe('applyTurnResult', () => {
      // released (not in state.unowned), so it does not enter GameState.unowned.
      territoryChanges: [{ nation: 'de', gain: ['POL', 'wales-bbbb'], lose: [] }],
      unowned: [],
-      nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+      nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result); // no validKeys -> nothing filtered
    expect(next.nations.de.territory).toContain('wales-bbbb');
@@ -1173,7 +1173,7 @@ describe('applyTurnResult (sole-ownership invariants, v0.21 #16 P2)', () => {
    regionChanges: [],
    relations: [],
    unowned: [],
-    nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+    nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
  };

  it('a double claim (two different gainers, one key) is rejected: the key stays with its original owner', () => {
@@ -1263,7 +1263,7 @@ describe('applyTurnResult (no man\'s land, v0.22 #16 P3)', () => {
    relations: [],
    territoryChanges: [],
    unowned: [],
-    nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+    nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
  };

  it('a release removes the key from its sole owner and marks it in GameState.unowned', () => {
@@ -1378,7 +1378,7 @@ describe('applyTurnResult (no man\'s land, v0.22 #16 P3)', () => {

  it('a lone release is meaningful (it survives the retry/nudge path)', () => {
    expect(
-      isMeaningful({ date: 'x', events: [], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [], unowned: ['GBR'], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] } }),
+      isMeaningful({ date: 'x', events: [], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [], unowned: ['GBR'], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] } }),
    ).toBe(true);
  });

@@ -1685,9 +1685,9 @@ describe('buildSystemPrompt (tool mode, v0.21 #16 P2)', () => {

 describe('isMeaningful', () => {
  it('is true with an event, false when everything is empty', () => {
-    expect(isMeaningful({ date: 'x', events: [{ nation: 'uk', type: 'military', title: 't', text: 'b', outcome: 'neutral' }], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [], unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] } })).toBe(true);
-    expect(isMeaningful({ date: 'x', events: [], stateChanges: [{ nation: 'uk', stat: 'military', op: 'set', value: 5 }], regionChanges: [], relations: [], territoryChanges: [], unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] } })).toBe(true);
-    expect(isMeaningful({ date: 'x', events: [], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [], unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] } })).toBe(false);
+    expect(isMeaningful({ date: 'x', events: [{ nation: 'uk', type: 'military', title: 't', text: 'b', outcome: 'neutral' }], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [], unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] } })).toBe(true);
+    expect(isMeaningful({ date: 'x', events: [], stateChanges: [{ nation: 'uk', stat: 'military', op: 'set', value: 5 }], regionChanges: [], relations: [], territoryChanges: [], unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] } })).toBe(true);
+    expect(isMeaningful({ date: 'x', events: [], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [], unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] } })).toBe(false);
  });

  it('(v0.23 #16 P4a) a turn that only proposes a nation-op is meaningful (it survives the retry/nudge path)', () => {
@@ -1700,7 +1700,7 @@ describe('isMeaningful', () => {
        relations: [],
        territoryChanges: [],
        unowned: [],
-        nationOps: [{ kind: 'rename', nationRef: 'de', to: 'Reich' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+        nationOps: [{ kind: 'rename', nationRef: 'de', to: 'Reich' }], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
      }),
    ).toBe(true);
  });
@@ -1721,8 +1721,7 @@ describe('isMeaningful', () => {
        hybrid: { ops: [] },
        economy: { trade: [], embargo: [] }, industry: { projects: [] },
        nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-        ideology: { changes: [] },
-        markers: { add: [{ type: 'city', name: 'Lyon', regionKey: 'rhone-rhne' }], remove: [] },
+        ideology: { changes: [] }, disasters: { events: [] },markers: { add: [{ type: 'city', name: 'Lyon', regionKey: 'rhone-rhne' }], remove: [] },
      }),
    ).toBe(true);
  });
@@ -1743,8 +1742,7 @@ describe('isMeaningful', () => {
        hybrid: { ops: [] },
        economy: { trade: [], embargo: [] }, industry: { projects: [] },
        nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-        ideology: { changes: [] },
-        markers: { add: [], remove: [] },
+        ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
      }),
    ).toBe(true);
  });
@@ -1767,8 +1765,7 @@ describe('takeovers (regime change, v0.32.0 #54)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result);
    expect(next.nations.de.name).toBe('The Reich');
@@ -1801,8 +1798,7 @@ describe('takeovers (regime change, v0.32.0 #54)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result);
    expect(next.playerNationId).toBe('uk'); // player still leads it
@@ -1826,8 +1822,7 @@ describe('takeovers (regime change, v0.32.0 #54)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result);
    // no nation was renamed
@@ -1854,8 +1849,7 @@ describe('takeovers (regime change, v0.32.0 #54)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result);
    // neither was renamed (ambiguous)
@@ -1881,8 +1875,7 @@ describe('takeovers (regime change, v0.32.0 #54)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    });
    expect(validated!.takeovers).toEqual([]);
    const next = applyTurnResult(state, validated!);
@@ -1908,8 +1901,7 @@ describe('takeovers (regime change, v0.32.0 #54)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result);
    expect(next.nations.uk.name).toBe('The Commonwealth');
@@ -1933,8 +1925,7 @@ describe('takeovers (regime change, v0.32.0 #54)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result);
    expect(next.version).toBe(2); // exactly one bump for the whole turn
@@ -1956,8 +1947,7 @@ describe('takeovers (regime change, v0.32.0 #54)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result);
    expect(next.nations.de.name).toBe('The Reich');
@@ -1991,8 +1981,7 @@ describe('markers (point placement, v0.27 #44)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [mk('city', 'Strasbourg', 'moselle-rygy')], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [mk('city', 'Strasbourg', 'moselle-rygy')], remove: [] },
    };
    const next = applyTurnResult(state, result, undefined, centroidOf);
    expect(next.markers).toHaveLength(1);
@@ -2016,13 +2005,13 @@ describe('markers (point placement, v0.27 #44)', () => {
    const add = [mk('city', 'Strasbourg', 'moselle-rygy')];
    const first = applyTurnResult(state, {
      date: '1939-09-03', events: [], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [],
-      unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add, remove: [] },
+      unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add, remove: [] },
    }, undefined, centroidOf);
    expect(first.markers).toHaveLength(1);
    // a second turn proposes the exact same marker again
    const second = applyTurnResult(first, {
      date: '1939-09-05', events: [], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [],
-      unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add, remove: [] },
+      unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add, remove: [] },
    }, undefined, centroidOf);
    expect(second.markers).toHaveLength(1);
    expect(second.markers[0].id).toBe(first.markers[0].id); // stable id, no second copy
@@ -2049,8 +2038,7 @@ describe('markers (point placement, v0.27 #44)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: {
+      ideology: { changes: [] }, disasters: { events: [] },markers: {
        add: [
          { type: 'city', name: 'Good', regionKey: 'moselle-rygy' }, // valid + centroid → kept
          { type: 'city', name: 'NoCent', regionKey: 'other-key' }, // in validKeys, no centroid → dropped
@@ -2097,8 +2085,7 @@ describe('markers (point placement, v0.27 #44)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: {
+      ideology: { changes: [] }, disasters: { events: [] },markers: {
        add: [
          { type: 'city', name: 'NewA', regionKey: 'new-a' },
          { type: 'city', name: 'NewB', regionKey: 'new-b' },
@@ -2123,7 +2110,7 @@ describe('markers (point placement, v0.27 #44)', () => {
    ];
    const next = applyTurnResult(state, {
      date: '1939-09-03', events: [], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [],
-      unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [idA, 'zzzz-not-there'] },
+      unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [idA, 'zzzz-not-there'] },
    }, undefined, centroidOf);
    expect(next.markers).toHaveLength(1);
    expect(next.markers[0].id).toBe(idB); // only A removed; the bogus id was a no-op
@@ -2139,14 +2126,14 @@ describe('markers (point placement, v0.27 #44)', () => {
    // 1) uk releases the region → the marker becomes ownerless
    const released = applyTurnResult(state, {
      date: '1939-09-03', events: [], stateChanges: [], regionChanges: [], relations: [], territoryChanges: [],
-      unowned: ['moselle-rygy'], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+      unowned: ['moselle-rygy'], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    }, undefined, centroidOf);
    expect(released.markers[0].ownerNationId).toBeNull();
    // 2) de re-claims the region → the marker's owner follows to de
    const reclaimed = applyTurnResult(released, {
      date: '1939-09-05', events: [], stateChanges: [], regionChanges: [], relations: [],
      territoryChanges: [{ nation: 'de', gain: ['moselle-rygy'], lose: [] }],
-      unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, markers: { add: [], remove: [] },
+      unowned: [], nationOps: [], takeovers: [], wars: { declare: [], end: [] }, hybrid: { ops: [] }, economy: { trade: [], embargo: [] }, industry: { projects: [] }, nuclear: { arm: [], strikes: [] }, leaders: { changes: [] }, ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    }, undefined, centroidOf);
    expect(reclaimed.markers[0].ownerNationId).toBe('de');
  });
@@ -2216,8 +2203,7 @@ describe('markers (point placement, v0.27 #44)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [{ type: 'city', name: 'Strasbourg', regionKey: 'moselle-rygy' }], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [{ type: 'city', name: 'Strasbourg', regionKey: 'moselle-rygy' }], remove: [] },
    });
    const { state } = await runTurn({
      llm: fakeLlm([result]),
@@ -2313,6 +2299,7 @@ function mkTurnResult(partial: Partial<TurnResult>): TurnResult {
    nuclear: partial.nuclear ?? { arm: [], strikes: [] },
    leaders: partial.leaders ?? { changes: [] },
    ideology: partial.ideology ?? { changes: [] },
+    disasters: partial.disasters ?? { events: [] },
    markers: partial.markers ?? { add: [], remove: [] },
  };
 }
@@ -3038,8 +3025,7 @@ describe('validateTakeovers (v0.32.0 #54)', () => {
      hybrid: { ops: [] },
      economy: { trade: [], embargo: [] }, industry: { projects: [] },
      nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-      ideology: { changes: [] },
-      markers: { add: [], remove: [] },
+      ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
    });
    expect(withTakeovers).not.toBeNull();
    // the valid one survives, the empty-name one is dropped
@@ -3427,8 +3413,7 @@ describe('isMeaningful — wars (v0.33.0 #56)', () => {
        hybrid: { ops: [] },
        economy: { trade: [], embargo: [] }, industry: { projects: [] },
        nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-        ideology: { changes: [] },
-        markers: { add: [], remove: [] },
+        ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
      }),
    ).toBe(true);
  });
@@ -3449,8 +3434,7 @@ describe('isMeaningful — wars (v0.33.0 #56)', () => {
        hybrid: { ops: [] },
        economy: { trade: [], embargo: [] }, industry: { projects: [] },
        nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-        ideology: { changes: [] },
-        markers: { add: [], remove: [] },
+        ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
      }),
    ).toBe(true);
  });
@@ -3471,8 +3455,7 @@ describe('isMeaningful — wars (v0.33.0 #56)', () => {
        hybrid: { ops: [] },
        economy: { trade: [], embargo: [] }, industry: { projects: [] },
        nuclear: { arm: [], strikes: [] }, leaders: { changes: [] },
-        ideology: { changes: [] },
-        markers: { add: [], remove: [] },
+        ideology: { changes: [] }, disasters: { events: [] },markers: { add: [], remove: [] },
      }),
    ).toBe(false);
  });
@@ -57,8 +57,9 @@ import {
  NEW_NATION_STATS,
  resolveNationRef,
  resolveRegionKey,
+  str,
 } from './abilities/shared';
-import { ABILITIES } from './abilities';
+import { ABILITIES, type AbilityCtx, type UserPromptCtx } from './abilities';
 // Re-exported so the existing callers (server/index.ts, the unit tests) keep
 // importing these shared primitives from the engine unchanged.
 export { freshNationId, freshWarId, NEW_NATION_STATS, resolveNationRef, resolveRegionKey };
@@ -86,6 +87,13 @@ export {
  validateTakeovers,
  validateWarOps,
  applyIndustryEffects,
+  validateDisasterEvents,
+  applyDisasterEvent,
+  isDisasterType,
+  isDisasterSeverity,
+  DISASTER_TYPES,
+  DISASTER_SEVERITIES,
+  DISASTER_EFFECTS,
 } from './abilities';

 // --- The LLM's getNeighbours tool (v0.21, #16 P2: contiguous region transfers) ---
@@ -458,7 +466,7 @@ export function buildUserPrompt(
  // (v0.40.0, #67) Build the UserPromptCtx once and merge each ability's
  // payload() at its exact position (the key order is load-bearing for the
  // golden test).
-  const upCtx = {
+  const upCtx: UserPromptCtx = {
    state,
    markers,
    wars,
@@ -468,14 +476,13 @@ export function buildUserPrompt(
    nationResources,
    industryProjects,
  };
-  const upCtxAny = upCtx as unknown as import('./abilities').UserPromptCtx;
-  Object.assign(payload, ABILITIES[0].payload(upCtxAny)); // takeovers → takeoverRisks
+  Object.assign(payload, ABILITIES[0].payload(upCtx)); // takeovers → takeoverRisks
  if (noMansLand !== undefined) payload.unowned = noMansLand;
  if (markers !== undefined) payload.markers = markers;
-  Object.assign(payload, ABILITIES[1].payload(upCtxAny)); // wars → wars
-  Object.assign(payload, ABILITIES[2].payload(upCtxAny)); // hybrid → relations
-  Object.assign(payload, ABILITIES[3].payload(upCtxAny)); // economy → trades, embargoes
-  Object.assign(payload, ABILITIES[4].payload(upCtxAny)); // industry → resources, industry
+  Object.assign(payload, ABILITIES[1].payload(upCtx)); // wars → wars
+  Object.assign(payload, ABILITIES[2].payload(upCtx)); // hybrid → relations
+  Object.assign(payload, ABILITIES[3].payload(upCtx)); // economy → trades, embargoes
+  Object.assign(payload, ABILITIES[4].payload(upCtx)); // industry → resources, industry
  return JSON.stringify(payload, null, 2);
 }

@@ -534,13 +541,6 @@ export function parseTurnResult(
  return validateTurnResult(obj, regionKeyResolver);
 }

-function str(s: unknown, max = 0): string | null {
-  if (typeof s !== 'string') return null;
-  const t = s.trim();
-  if (!t) return null;
-  return max ? t.slice(0, max) : t;
-}
-
 /**
 * Validate a raw (LLM) `nationOps` array into safe {@link NationOp} values
 * (v0.23, #16 P4a). Defensive like the rest of the parser: entries with an
@@ -621,6 +621,7 @@ export function validateTurnResult(
    nuclear: { arm: [], strikes: [] },
    leaders: { changes: [] },
    ideology: { changes: [] },
+    disasters: { events: [] },
    markers: { add: [], remove: [] },
  };

@@ -711,7 +712,7 @@ export function validateTurnResult(
  // list for the player to confirm/reject.
  result.nationOps = validateNationOps(o.nationOps);

-  // The 8 per-feature LLM abilities (v0.40.0, #67): each one's validate call
+  // The 9 per-feature LLM abilities (v0.40.0, #67): each one's validate call
  // is owned by its Ability module in the ABILITIES registry. The field's raw
  // value is passed through a.validate() which returns the validated field shape.
  for (const a of ABILITIES) {
@@ -824,19 +825,6 @@ export function validateRegionChanges(
  return out;
 }

-/**
- * (v0.32.0, #54) Validate the raw `takeovers` array of a turn into a safe
- * {@link Takeover} list — the non-military regime-change lever (a coup or
- * revolution that renames a nation to its new regime name). Defensive like
- * the rest of the parser — never throws. Each entry needs a non-empty
- * `nationRef` (the target nation's id or name — capped at 200 chars) and a
- * non-empty `newRegimeName` (capped at 200 chars). Resolution of `nationRef`
- * to a concrete nation id happens at apply time (`resolveNationRef`), not
- * here. Entries with either field missing or whitespace-only are dropped.
- */
-  // (v0.40.0, #67) The 8 per-feature ability validators, appliers, and helpers
-  // have been moved to server/abilities/ — re-exported below for the tests.
-
 export function isMeaningful(result: TurnResult): boolean {
  return (
    result.events.length > 0 ||
@@ -845,7 +833,7 @@ export function isMeaningful(result: TurnResult): boolean {
    result.regionChanges.length > 0 ||
    result.unowned.length > 0 ||
    result.nationOps.length > 0 ||
-    // (v0.40.0, #67) any of the 8 per-feature abilities having a non-empty
+    // (v0.40.0, #67) any of the 9 per-feature abilities having a non-empty
    // payload is a real world change (each Ability's isMeaningful predicate
    // is the per-ability half of the old 18-sub-field check).
    ABILITIES.some((a) => a.isMeaningful(result[a.field])) ||
@@ -1112,12 +1100,12 @@ export function applyTurnResult(
    n.stats = deriveNationStats(n.territory, next.regionStats, geoOf);
  }

-  // (v0.40.0, #67) The 8 per-feature LLM abilities, applied in ABILITIES
+  // (v0.40.0, #67) The 9 per-feature LLM abilities, applied in ABILITIES
  // order (takeovers → wars → hybrid → economy → industry → nuclear →
-  // leaders → ideology). Each Ability's apply method handles its own
-  // field's validated data against the post-territory/post-recompute
+  // leaders → ideology → disasters). Each Ability's apply method handles its
+  // own field's validated data against the post-territory/post-recompute
  // `next` state. The AbilityCtx carries the shared resolvers.
-  const abilityCtx = {
+  const abilityCtx: AbilityCtx = {
    previous: state,
    actingTurn,
    validRegionKeys: validKeys,
@@ -1126,9 +1114,8 @@ export function applyTurnResult(
    resourceOf,
    centroidOf,
  };
-  const abilityCtxAny = abilityCtx as unknown as import('./abilities').AbilityCtx;
  for (const a of ABILITIES) {
-    a.apply(next, result[a.field], abilityCtxAny);
+    a.apply(next, result[a.field], abilityCtx);
  }

  // --- Map markers (v0.27, #44) ---
@@ -252,13 +252,13 @@ export function deterministicTurn(p: StubPayload): TurnResult {
    nationOps: [], // the stub never proposes nation ops (see doc comment)
  };

-  // The 8 ability fields, filled by the registry in its canonical order. The
+  // The 9 ability fields, filled by the registry in its canonical order. The
  // stub is ability-inert: every ability contributes its own no-op default
  // (each ability's `stub()` — see the per-ability doc comments above), so the
  // e2e assertions are unaffected. The insertion order here (ABILITIES) is the
  // historical key order pinned by the stub's deterministic output
  // (takeovers → wars → hybrid → economy → industry → nuclear → leaders →
-  // ideology), which must stay byte-identical.
+  // ideology → disasters), which must stay byte-identical.
  const abilities = {} as Record<AbilityField, unknown>;
  for (const a of ABILITIES) abilities[a.field] = a.stub();

@@ -598,6 +598,58 @@ export function isNuclearCapable(nation: Nation, markers: readonly MapMarker[]):
  return markers.some((m) => m.ownerNationId === nation.id && m.type === 'rocket');
 }

+// --- Disasters & pandemics (v0.41.0, #63) ------------------------------------
+//
+// Natural and man-made catastrophes — earthquakes, floods, volcanic eruptions,
+// wildfires, famines, plagues, and epidemics — hit a nation or a single region
+// each turn. Each event carries a `type` and a `severity`; the engine applies
+// a DETERMINISTIC stat dip chosen from the `(type, severity)` lookup table
+// `DISASTER_EFFECTS` (defined in `server/abilities/disasters.ts`) — no hidden
+// randomness: the LLM chooses the type and severity, the table decides the
+// magnitude. The dip is clamped to 0–100, mirrored to the target's regions
+// (`regionStats`), and the target's derived `stats` re-derived afterwards
+// (the same 0-region / no-entry guards as the hybrid / economy layers). It is
+// **turn-transient** like the hybrid layer: there is NO `GameState` field, no
+// durable list, and no `db.ts` change — an ongoing plague / epidemic is simply
+// re-declared each turn it persists. Disasters never move territory (sole
+// ownership is untouched) and never touch `population`.
+
+/** The kind of catastrophe a disaster event describes (v0.41.0, #63). */
+export type DisasterType =
+  | 'earthquake'
+  | 'flood'
+  | 'volcanic'
+  | 'wildfire'
+  | 'famine'
+  | 'plague'
+  | 'epidemic';
+
+/** The severity a disaster event carries (v0.41.0, #63). */
+export type DisasterSeverity = 'minor' | 'moderate' | 'severe';
+
+/**
+ * A single disaster event (v0.41.0, #63): the catastrophe `type`, its
+ * `target` (a nation id / name, or a region key that hits that region's sole
+ * owner — resolved at apply time), the `severity`, and an optional short
+ * `detail`. The deterministic stat dip is looked up from
+ * `DISASTER_EFFECTS[type][severity]`.
+ */
+export interface DisasterEvent {
+  /** The kind of catastrophe (one of {@link DisasterType}). */
+  type: DisasterType;
+  /** The affected nation (by id or name) or a region key (hits its sole owner). */
+  target: string;
+  /** How bad it was (one of {@link DisasterSeverity}). */
+  severity: DisasterSeverity;
+  /** Optional short annotation (≤300 chars). */
+  detail?: string;
+}
+
+/** The disasters block of a `TurnResult`. Required; default `{ events: [] }`. */
+export interface DisastersOps {
+  events: DisasterEvent[];
+}
+
 /** The exact JSON object the world-simulator LLM must return for a turn. */
 export interface TurnResult {
  date: string;
@@ -749,6 +801,24 @@ export interface TurnResult {
   * Required; default `{ changes: [] }`.
   */
  ideology: IdeologyOps;
+  /**
+   * (v0.41.0, #63) Disasters & pandemics that struck this turn — earthquakes,
+   * floods, volcanic eruptions, wildfires, famines, plagues, and epidemics,
+   * each hitting a **nation** (by id or name) or a single **region** (by key,
+   * which hits that region's SOLE owner — a key with 0 or 2+ owners can't be
+   * hit). Each event names a `type` (one of the seven `DisasterType`s) and a
+   * `severity` (minor / moderate / severe); the engine applies a small,
+   * DETERMINISTIC stat dip from the `(type, severity)` table
+   * (`DISASTER_EFFECTS`, in `server/abilities/disasters.ts`) — clamped to
+   * 0–100, mirrored to the target's regions, and the target's derived `stats`
+   * re-derived afterwards (no hidden randomness). They NEVER move borders
+   * (sole ownership is untouched) and never touch `population`, and the layer
+   * is turn-transient (no durable state): an ongoing plague / epidemic is
+   * simply re-declared each turn it persists. At most 1–2 events per turn,
+   * each narrated in `events` (a `disaster` event). Required; default
+   * `{ events: [] }`.
+   */
+  disasters: DisastersOps;
  /**
   * (v0.27, #44) Map-marker ops this turn. `add` places new named markers
   * (the engine positions each at its region's centroid + a small