import { describe, expect, it } from 'vitest';
import type { GameState, MarkerType, Nation, NationStats, Preset, RegionStats, RoundItem } from '../shared/types';
import { makeEvent, markerId, MAX_MARKERS, seedRegionStats, type MarkerSpec, type NationOp, type TurnResult } from '../shared/protocol';
import type { LlmClient, ToolDefinition, WireMessage } from './llm';
import { makeStubLlmClient } from './stub';
import {
  applyNationOp,
  applyTurnResult,
  buildSystemPrompt,
  buildUserPrompt,
  confirmNationOp,
  freshNationId,
  GET_NEIGHBOURS_TOOL,
  isMeaningful,
  makeNeighboursExecutor,
  NEW_NATION_STATS,
  parseTurnResult,
  playerFrontier,
  queueRoundItem,
  rejectNationOp,
  removeRoundItem,
  resolveNationRef,
  runTurn,
  validateMarkerOps,
  validateNationOps,
  validateTurnResult,
} from './engine';

/** A fake LlmClient that returns a fixed list of raw responses in order. */
function fakeLlm(responses: string[]): LlmClient {
  let i = 0;
  return {
    chat: async () => responses[Math.min(i++, responses.length - 1)],
    listModels: async () => [],
  };
}

const preset: Preset = {
  id: 'test',
  title: 'Test',
  startDate: '1939-09-01',
  summary: '',
  worldBackground: 'A test world.',
  simulationRules: ['Prefer gradual change'],
  nations: [
    {
      id: 'uk',
      name: 'UK',
      type: 'major',
      stats: { military: 80, economy: 70, stability: 60, population: 50 },
      territory: ['GBR'],
      relations: { us: 'neutral', de: 'hostile' },
    },
    {
      id: 'us',
      name: 'US',
      type: 'major',
      stats: { military: 60, economy: 90, stability: 80, population: 80 },
      territory: ['USA'],
      relations: { uk: 'neutral' },
    },
    {
      id: 'de',
      name: 'DE',
      type: 'major',
      stats: { military: 95, economy: 70, stability: 75, population: 90 },
      territory: ['DEU'],
      relations: {},
    },
  ],
};

function baseState(): GameState {
  const nations: GameState['nations'] = {
    uk: { ...preset.nations[0], stats: { ...preset.nations[0].stats }, territory: [...preset.nations[0].territory], relations: { ...preset.nations[0].relations } },
    us: { ...preset.nations[1], stats: { ...preset.nations[1].stats }, territory: [...preset.nations[1].territory], relations: { ...preset.nations[1].relations } },
    de: { ...preset.nations[2], stats: { ...preset.nations[2].stats }, territory: [...preset.nations[2].territory], relations: { ...preset.nations[2].relations } },
  };
  return {
    id: 'g1',
    presetId: 'test',
    presetTitle: 'Test',
    playerNationId: 'uk',
    turn: 1,
    date: '1939-09-01',
    nations,
    events: [],
    pending: [],
    version: 1,
    unowned: [],
    pendingNationOps: [],
    markers: [],
    // (v0.28, #46) every owned region starts as a copy of its owner's stats,
    // so a fresh state's derived stats equal its nation-level stats.
    regionStats: seedRegionStats(nations),
  };
}

const validResult = JSON.stringify({
  date: '1939-09-03',
  events: [
    { nation: 'uk', type: 'military', title: 'T-26s cross the border', text: 'The border is breached.', outcome: 'success' },
  ],
  stateChanges: [
    { nation: 'uk', stat: 'military', op: 'set', value: 85 },
    { nation: 'de', stat: 'economy', op: 'add', value: 10 },
  ],
  relations: [{ a: 'uk', b: 'us', set: 'ally' }],
  // v0.21 (#16 P2): DE gains the UK's GBR — the key has exactly one previous
  // owner, so the transfer applies (since v0.22 #16 P3 a key owned by NOBODY
  // would be re-claimed instead of ignored; a release lives in "unowned").
  territoryChanges: [{ nation: 'de', gain: ['GBR'], lose: [] }],
});

describe('runTurn', () => {
  it('applies a canned TurnResult: stats, symmetric relations, territory, event, turn, date, pending cleared', async () => {
    const original = baseState();
    const { state, result } = await runTurn({
      llm: fakeLlm([validResult]),
      preset,
      state: original,
      items: [{ kind: 'action', text: 'We rearm the coast' }],
    });

    expect(state.turn).toBe(2); // the turn counter advanced
    expect(state.date).toBe('1939-09-03');
    expect(state.pending).toEqual([]); // committing a round always clears it
    expect(state.nations.uk.stats.military).toBe(85);
    expect(state.nations.de.stats.economy).toBe(80); // 70 + 10 (add)
    // relations are symmetric
    expect(state.nations.uk.relations.us).toBe('ally');
    expect(state.nations.us.relations.uk).toBe('ally');
    // territory moved to DE: it gains GBR (the UK's sole previous owner) and
    // the old owner correspondingly loses it (v0.21 #16 P2: one owner per key)
    expect(state.nations.de.territory).toContain('GBR');
    expect(state.nations.uk.territory).not.toContain('GBR');
    // one event appended, tagged with the turn that was resolved (1)
    expect(state.events).toHaveLength(1);
    expect(state.events[0].turn).toBe(1);
    expect(state.events[0].title).toBe('T-26s cross the border');
    expect(state.events[0].nation).toBe('uk');
    // the return value carries the validated result too
    expect(result.events[0].title).toBe('T-26s cross the border');
    // and the original state object is NOT mutated
    expect(original.turn).toBe(1);
    expect(original.nations.uk.stats.military).toBe(80);
    expect(original.nations.de.territory).not.toContain('GBR');
    expect(original.nations.uk.territory).toContain('GBR');
  });

  it('clamps out-of-range stat values into 0-100', async () => {
    const clampResult = JSON.stringify({
      date: '1939-09-03',
      events: [{ nation: 'uk', type: 'economic', title: 'cap', text: 'x', outcome: 'neutral' }],
      stateChanges: [
        { nation: 'uk', stat: 'military', op: 'set', value: 250 },
        { nation: 'uk', stat: 'stability', op: 'set', value: -20 },
      ],
      relations: [],
      territoryChanges: [],
    });
    const { state } = await runTurn({
      llm: fakeLlm([clampResult]),
      preset,
      state: baseState(),
      items: [],
    });
    expect(state.nations.uk.stats.military).toBe(100);
    expect(state.nations.uk.stats.stability).toBe(0);
  });

  it('survives an invalid-JSON response: no throw, advances turn, emits a generic event', async () => {
    const { state, result } = await runTurn({
      llm: fakeLlm(['total garbage', 'still not json']),
      preset,
      state: baseState(),
      items: [],
    });
    expect(state.turn).toBe(2);
    expect(state.events).toHaveLength(1);
    expect(state.events[0].title).toBe('The turn was unclear');
    expect(result.events[0].title).toBe('The turn was unclear');
  });

  it('treats a valid-but-empty result as unclear (not meaningful)', async () => {
    const emptyResult = JSON.stringify({
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
    });
    const { state } = await runTurn({
      llm: fakeLlm([emptyResult, emptyResult]),
      preset,
      state: baseState(),
      items: [],
    });
    expect(state.turn).toBe(2);
    expect(state.events[0].title).toBe('The turn was unclear');
  });

  it('"jump forward" (no action) still advances the turn and emits an event', async () => {
    const state = baseState();
    state.turn = 3; // start mid-game
    const { state: next } = await runTurn({
      llm: fakeLlm([validResult]),
      preset,
      state, // no items = an empty round / jump forward
      items: [],
    });
    expect(next.turn).toBe(4);
    expect(next.events).toHaveLength(1);
  });
});

describe('runTurn (batched round, deterministic stub)', () => {
  it('a single action item: turn+1, date+2, pending cleared, one military event, military set to clamp(cur+5)', async () => {
    const original = baseState();
    original.pending = [{ kind: 'action', text: 'Fortify the coast and mobilize the home guard' }];
    const { state, result } = await runTurn({
      llm: makeStubLlmClient(),
      preset,
      state: original,
      items: original.pending,
    });
    expect(state.turn).toBe(2);
    expect(state.date).toBe('1939-09-03');
    expect(state.pending).toEqual([]);
    expect(state.nations.uk.stats.military).toBe(85); // clamp(80 + 5)
    expect(state.events).toHaveLength(1);
    expect(state.events[0].type).toBe('military');
    expect(state.events[0].nation).toBe('uk');
    expect(state.events[0].outcome).toBe('success');
    expect(result.stateChanges).toEqual([{ nation: 'uk', stat: 'military', op: 'set', value: 85 }]);
    // committing a turn is a new revision too
    expect(state.version).toBe(2);
    // the original object is not mutated (a fresh queue was consumed)
    expect(original.pending).toHaveLength(1);
    expect(original.version).toBe(1);
  });

  it('an empty round: turn advances, one political "world moves on" event, pending stays empty', async () => {
    const { state } = await runTurn({
      llm: makeStubLlmClient(),
      preset,
      state: baseState(), // pending: []
      items: [],
    });
    expect(state.turn).toBe(2);
    expect(state.date).toBe('1939-09-03');
    expect(state.pending).toEqual([]);
    expect(state.events).toHaveLength(1);
    expect(state.events[0].type).toBe('political');
    expect(state.events[0].title).toBe('The world moves on');
    expect(state.events[0].outcome).toBe('neutral');
  });

  it('a round with two actions and one diplomacy: 3 events (2 military + 1 diplomatic), exactly one turn advance', async () => {
    const state = baseState();
    state.pending = [
      { kind: 'action', text: 'Reinforce the Atlantic convoys' },
      { kind: 'action', text: 'Expand the shipyards' },
      { kind: 'diplomacy', to: 'us', text: 'Propose a mutual defense pact' },
    ];
    const { state: next } = await runTurn({
      llm: makeStubLlmClient(),
      preset,
      state,
      items: state.pending,
    });
    expect(next.turn).toBe(2); // a whole batch = one turn
    expect(next.pending).toEqual([]);
    expect(next.events).toHaveLength(3);
    expect(next.events.filter((e) => e.type === 'military')).toHaveLength(2);
    expect(next.events.filter((e) => e.type === 'diplomatic')).toHaveLength(1);
    expect(next.nations.uk.stats.military).toBe(85); // one +5 per turn, not per item
  });
});

describe('buildUserPrompt (batched round)', () => {
  it('includes every queued item (action + diplomacy) in the emitted payload', () => {
    const items: RoundItem[] = [
      { kind: 'action', text: 'Fortify Dover' },
      { kind: 'diplomacy', to: 'us', text: 'Propose a pact' },
    ];
    const parsed = JSON.parse(buildUserPrompt(baseState(), items)) as {
      pending: RoundItem[];
      playerActions: unknown[];
      roundInstruction: string;
    };
    expect(parsed.pending).toEqual(items);
    expect(parsed.playerActions).toEqual(['Fortify Dover', { to: 'us', message: 'Propose a pact' }]);
    expect(parsed.roundInstruction).toContain('Fortify Dover');
    expect(parsed.roundInstruction).toContain('Propose a pact');
  });

  it('frames an empty round as "the world advances on its own momentum"', () => {
    const parsed = JSON.parse(buildUserPrompt(baseState(), [])) as {
      pending: RoundItem[];
      roundInstruction: string;
    };
    expect(parsed.pending).toEqual([]);
    expect(parsed.roundInstruction).toMatch(/no action/i);
    expect(parsed.roundInstruction).toMatch(/own momentum/i);
  });

  it('caps recentEvents at the last 5 (in order) when the state has more than 5 events', () => {
    const state = baseState();
    const events = Array.from({ length: 8 }, (_, i) =>
      makeEvent(
        {
          nation: 'uk',
          type: 'political',
          title: `Event ${i + 1}`,
          text: `Narrative ${i + 1}`,
          outcome: 'neutral',
        },
        i + 1,
        `1939-09-0${i + 1}`,
      ),
    );
    state.events = events;

    const parsed = JSON.parse(buildUserPrompt(state, [])) as {
      state: { recentEvents: Array<{ title: string; turn: number; date: string }> };
    };

    expect(parsed.state.recentEvents).toHaveLength(5);
    // the last 5 of the 8 input events, in order
    expect(parsed.state.recentEvents[0].title).toBe(events[3].title); // 'Event 4'
    expect(parsed.state.recentEvents[4].title).toBe(events[7].title); // 'Event 8'
    expect(parsed.state.recentEvents.map((e) => e.title)).toEqual([
      events[3].title,
      events[4].title,
      events[5].title,
      events[6].title,
      events[7].title,
    ]);
  });

  it('asks the model to keep its internal reasoning brief (concise-CoT constraint)', () => {
    expect(buildSystemPrompt(preset)).toMatch(/reasoning brief|a few sentences/i);
  });

  it('includes a regions reference table only when one is provided', () => {
    // with a reference table: the payload carries it (region key -> "name (parent)")
    const withRef = JSON.parse(
      buildUserPrompt(baseState(), [], { 'ain-lqtt': 'Ain (FRA)', 'wales-bbbb': 'Wales (GBR)' }),
    ) as { regions?: Record<string, string> };
    expect(withRef.regions).toEqual({ 'ain-lqtt': 'Ain (FRA)', 'wales-bbbb': 'Wales (GBR)' });
    // without one: the field is absent entirely (the legacy prompt shape is unchanged)
    const withoutRef = JSON.parse(buildUserPrompt(baseState(), [])) as { regions?: Record<string, string> };
    expect(withoutRef.regions).toBeUndefined();
  });

  it('(v0.22 #16 P3) emits the no-man\'s-land list when provided (even when empty) and omits it otherwise', () => {
    // runTurn always passes state.unowned (even []), so the field is present...
    const withEmpty = JSON.parse(buildUserPrompt(baseState(), [], undefined, undefined, [])) as {
      unowned?: string[];
    };
    expect(withEmpty.unowned).toEqual([]);
    // ...and a populated list reaches the model verbatim (it knows what it can re-claim)
    const withKeys = JSON.parse(
      buildUserPrompt(baseState(), [], undefined, undefined, ['GBR', 'POL']),
    ) as { unowned?: string[] };
    expect(withKeys.unowned).toEqual(['GBR', 'POL']);
    // but a caller that does not provide it keeps the legacy payload shape
    const omitted = JSON.parse(buildUserPrompt(baseState(), [])) as { unowned?: string[] };
    expect(omitted.unowned).toBeUndefined();
  });
});

describe('queueRoundItem', () => {
  it('appends an item to pending without advancing the turn or the date', () => {
    const before = baseState();
    const after = queueRoundItem(before, { kind: 'diplomacy', to: 'us', text: 'hello' });
    expect(after.turn).toBe(before.turn);
    expect(after.date).toBe(before.date);
    expect(after.pending).toHaveLength(1);
    expect(after.pending[0]).toEqual({ kind: 'diplomacy', to: 'us', text: 'hello' });
    // the original state is not mutated
    expect(before.pending).toHaveLength(0);
    expect(before.version).toBe(1);
  });

  it('bumps the monotonic version on each queue mutation', () => {
    const a = queueRoundItem(baseState(), { kind: 'action', text: 'one' });
    expect(a.version).toBe(2);
    const b = queueRoundItem(a, { kind: 'action', text: 'two' });
    expect(b.version).toBe(3);
    // and never backwards: two consecutive adds from the same base both
    // advance past it, so a late snapshot of the older state is always older.
    const b2 = queueRoundItem(baseState(), { kind: 'action', text: 'two' });
    expect(b2.version).toBe(2);
    expect(b.version).toBeGreaterThan(b2.version);
  });

  it('treats a legacy state without a version field as version 0', () => {
    const legacy = { ...baseState() } as Omit<GameState, 'version'> & { version?: number };
    delete legacy.version; // a row saved before the version field existed
    // simulate a legacy row coming back from SQLite: the JSON has no field.
    const after = queueRoundItem(legacy as unknown as GameState, {
      kind: 'action',
      text: 'first after upgrade',
    });
    expect(after.version).toBe(1);
  });
});

describe('removeRoundItem', () => {
  it('removes the item at the index, bumps the version, and leaves the input untouched', () => {
    const state = baseState();
    state.pending = [
      { kind: 'action', text: 'one' },
      { kind: 'diplomacy', to: 'us', text: 'two' },
      { kind: 'action', text: 'three' },
    ];
    const next = removeRoundItem(state, 1);
    expect(next).not.toBeNull();
    expect(next!.version).toBe(2);
    expect(next!.pending).toEqual([
      { kind: 'action', text: 'one' },
      { kind: 'action', text: 'three' },
    ]);
    expect(state.pending).toHaveLength(3); // original untouched
    expect(state.version).toBe(1);
  });

  it('returns null for out-of-bounds or non-integer indices (route answers 400, nothing mutates)', () => {
    const state = baseState();
    state.pending = [{ kind: 'action', text: 'one' }];
    expect(removeRoundItem(state, -1)).toBeNull();
    expect(removeRoundItem(state, 1)).toBeNull(); // == length
    expect(removeRoundItem(state, 5)).toBeNull();
    expect(removeRoundItem(state, 0.5)).toBeNull();
    expect(removeRoundItem(state, Number.NaN)).toBeNull();
    expect(state.pending).toHaveLength(1); // still untouched
  });
});

describe('resolveNationRef (v0.23 #16 P4a)', () => {
  it('resolves an exact id first (even if a name matches something else)', () => {
    const state = baseState();
    expect(resolveNationRef(state, 'de')).toBe('de');
  });

  it('resolves a unique name case-insensitively', () => {
    const state = baseState();
    expect(resolveNationRef(state, 'US')).toBe('us');
    expect(resolveNationRef(state, ' uS ')).toBe('us'); // trimmed, case-insensitive
  });

  it('returns null for an ambiguous name (two nations share it)', () => {
    const state = baseState();
    state.nations.us.name = 'UK'; // now uk and us are both "UK"
    expect(resolveNationRef(state, 'UK')).toBeNull();
    // but the exact id still resolves
    expect(resolveNationRef(state, 'uk')).toBe('uk');
  });

  it('returns null for an unknown or empty reference (never throws)', () => {
    const state = baseState();
    expect(resolveNationRef(state, 'zzz-not-a-nation')).toBeNull();
    expect(resolveNationRef(state, '   ')).toBeNull();
    expect(resolveNationRef(state, '')).toBeNull();
  });
});

describe('validateNationOps (v0.23 #16 P4a)', () => {
  it('parses a valid rename (trimmed, capped) and drops invalid ones', () => {
    const ops = validateNationOps([
      { kind: 'rename', nationRef: ' de ', to: 'Reich' },
      { kind: 'rename', nationRef: 'uk', to: '' }, // empty to -> dropped
      { kind: 'rename', to: 'no ref' }, // missing nationRef -> dropped
      { kind: 'rename', nationRef: 'us' }, // missing to -> dropped
      { kind: 'bogus-kind' }, // unknown kind -> ignored
      'not-an-object',
      null,
    ]);
    expect(ops).toEqual([{ kind: 'rename', nationRef: 'de', to: 'Reich' }]);
  });

  it('parses a valid split (parts with names kept, nameless parts dropped)', () => {
    const ops = validateNationOps([
      {
        kind: 'split',
        nationRef: 'de',
        parts: [
          { name: 'East', territory: ['DEU', ''] },
          { name: '   ' }, // empty name -> part dropped
          { name: 'West' },
        ],
      },
    ]);
    expect(ops).toEqual([
      {
        kind: 'split',
        nationRef: 'de',
        parts: [{ name: 'East', territory: ['DEU'] }, { name: 'West', territory: [] }],
      },
    ]);
    // a split with no usable parts is dropped entirely
    expect(validateNationOps([{ kind: 'split', nationRef: 'de', parts: [{ name: '' }] }])).toEqual([]);
  });

  it('parses a valid merge and drops malformed ones', () => {
    const ops = validateNationOps([
      { kind: 'merge', nationRefs: ['uk', 'us'], survivingRef: 'uk', into: 'Anglo-Saxon Union' },
      { kind: 'merge', nationRefs: [], survivingRef: 'uk', into: 'X' }, // no refs -> dropped
      { kind: 'merge', nationRefs: ['uk'], survivingRef: '', into: 'X' }, // no survivor -> dropped
      { kind: 'merge', nationRefs: ['uk'], survivingRef: 'uk' }, // no into -> dropped
    ]);
    expect(ops).toEqual([
      { kind: 'merge', nationRefs: ['uk', 'us'], survivingRef: 'uk', into: 'Anglo-Saxon Union' },
    ]);
  });

  it('returns [] for non-array input and is never thrown by', () => {
    expect(validateNationOps(undefined)).toEqual([]);
    expect(validateNationOps('nope')).toEqual([]);
    expect(validateNationOps({})).toEqual([]);
  });

  it('validateTurnResult carries validated nationOps through (and defaults to [] when absent)', () => {
    const withOps = validateTurnResult({
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: [],
      nationOps: [{ kind: 'rename', nationRef: 'France', to: 'French Republic' }], markers: { add: [], remove: [] },
    });
    expect(withOps).not.toBeNull();
    expect(withOps!.nationOps).toEqual([{ kind: 'rename', nationRef: 'France', to: 'French Republic' }]);

    const without = validateTurnResult({ date: '1939-09-03', events: [], stateChanges: [] });
    expect(without).not.toBeNull();
    expect(without!.nationOps).toEqual([]);
  });
});

describe('applyTurnResult (nation-op proposals, v0.23 #16 P4a)', () => {
  it('a proposed rename is NOT applied by the turn — it lands in pendingNationOps, name untouched', () => {
    const state = baseState();
    const next = applyTurnResult(state, {
      date: '1939-09-03',
      events: [{ nation: 'de', type: 'political', title: 'Reunification', text: 'The nation is renamed.', outcome: 'success' }],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: [],
      nationOps: [{ kind: 'rename', nationRef: 'de', to: 'Reich' }], markers: { add: [], remove: [] },
    });
    expect(next.nations.de.name).toBe('DE'); // still the old name
    expect(next.pendingNationOps).toEqual([{ kind: 'rename', nationRef: 'de', to: 'Reich' }]);
    expect(next.version).toBe(2);
    // the input is not mutated
    expect(state.nations.de.name).toBe('DE');
    expect(state.pendingNationOps).toEqual([]);
  });

  it('pending proposals SURVIVE a subsequent turn (unlike the round queue) and new ones append', () => {
    const state = baseState();
    state.pendingNationOps = [{ kind: 'rename', nationRef: 'de', to: 'Reich' }]; // unresolved from turn N-1
    const next = applyTurnResult(state, {
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: [],
      nationOps: [{ kind: 'rename', nationRef: 'us', to: 'USA' }], markers: { add: [], remove: [] }, // new proposal this turn
    });
    expect(next.pendingNationOps).toEqual([
      { kind: 'rename', nationRef: 'de', to: 'Reich' }, // the old one survived
      { kind: 'rename', nationRef: 'us', to: 'USA' }, // the new one was appended
    ]);
  });

  it('a legacy state without the pendingNationOps field accepts proposals (defaulted to [])', () => {
    const state = baseState();
    delete (state as { pendingNationOps?: NationOp[] }).pendingNationOps; // simulate a pre-v0.23 row
    const next = applyTurnResult(state, {
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: [],
      nationOps: [{ kind: 'rename', nationRef: 'de', to: 'Reich' }], markers: { add: [], remove: [] },
    });
    expect(next.pendingNationOps).toEqual([{ kind: 'rename', nationRef: 'de', to: 'Reich' }]);
  });
});

describe('confirmNationOp / rejectNationOp (v0.23 #16 P4a)', () => {
  /**
   * The pending list: op 0 is referenced by id ('de'); op 1 is referenced by
   * NAME ('US' — the id is lowercase 'us'), so confirming it exercises the
   * name-resolution path of resolveNationRef.
   */
  function stateWithPending(): GameState {
    const s = baseState();
    s.pendingNationOps = [
      { kind: 'rename', nationRef: 'de', to: 'Reich' },
      { kind: 'rename', nationRef: 'US', to: 'United States' },
    ];
    return s;
  }

  it('confirm applies a rename (name only — id/territory/relations/player pointer untouched) and removes the op, bumping the version', () => {
    const state = stateWithPending();
    const next = confirmNationOp(state, 0);
    expect(next).not.toBeNull();
    expect(next!.nations.de.name).toBe('Reich');
    expect(next!.nations.de.id).toBe('de'); // id unchanged
    expect(next!.nations.de.territory).toEqual(['DEU']); // territory unchanged
    expect(next!.nations.uk.relations.de).toBe('hostile'); // relations (keyed by id) unchanged
    expect(next!.playerNationId).toBe('uk'); // player pointer unchanged
    expect(next!.pendingNationOps).toEqual([{ kind: 'rename', nationRef: 'US', to: 'United States' }]);
    expect(next!.version).toBe(2);
    // the input state is not mutated
    expect(state.nations.de.name).toBe('DE');
    expect(state.pendingNationOps).toHaveLength(2);
    expect(state.version).toBe(1);
  });

  it('confirm with an edits.name override renames to the player-edited name', () => {
    const next = confirmNationOp(stateWithPending(), 0, { name: 'Greater Reich' });
    expect(next!.nations.de.name).toBe('Greater Reich');
  });

  it('confirm with an empty edits.name falls back to the proposed name', () => {
    const next = confirmNationOp(stateWithPending(), 0, { name: '   ' });
    expect(next!.nations.de.name).toBe('Reich');
  });

  it('confirm resolves the target by name (not just id) — case-insensitively', () => {
    const next = confirmNationOp(stateWithPending(), 1); // nationRef 'US' is a name, not the id 'us'
    expect(next).not.toBeNull();
    expect(next!.nations.us.name).toBe('United States');
  });

  it('confirm of a 1-part split is a no-op on the world (fewer than 2 parts) — the op is still removed', () => {
    const state = baseState();
    state.pendingNationOps = [{ kind: 'split', nationRef: 'de', parts: [{ name: 'East' }] }];
    const next = confirmNationOp(state, 0);
    expect(next).not.toBeNull();
    expect(next!.nations).toEqual(state.nations); // the world is untouched
    expect(next!.pendingNationOps).toEqual([]); // ...but the proposal was resolved
    expect(next!.version).toBe(2);
  });

  it('confirm with an invalid index returns null and mutates nothing', () => {
    const state = stateWithPending();
    expect(confirmNationOp(state, -1)).toBeNull();
    expect(confirmNationOp(state, 2)).toBeNull();
    expect(confirmNationOp(state, 0.5)).toBeNull();
    expect(state.nations.de.name).toBe('DE');
    expect(state.version).toBe(1);
  });

  it('reject drops the proposal without applying it, bumping the version', () => {
    const state = stateWithPending();
    const next = rejectNationOp(state, 0);
    expect(next).not.toBeNull();
    expect(next!.nations.de.name).toBe('DE'); // unchanged
    expect(next!.pendingNationOps).toEqual([{ kind: 'rename', nationRef: 'US', to: 'United States' }]);
    expect(next!.version).toBe(2);
    expect(state.pendingNationOps).toHaveLength(2); // input untouched
  });

  it('reject with an invalid index returns null and mutates nothing', () => {
    const state = stateWithPending();
    expect(rejectNationOp(state, -1)).toBeNull();
    expect(rejectNationOp(state, 2)).toBeNull();
    expect(state.pendingNationOps).toHaveLength(2);
    expect(state.version).toBe(1);
  });

  it('an ambiguous/invalid nationRef is a no-op on confirm (the op is resolved, the world unchanged)', () => {
    const state = baseState();
    state.nations.us.name = 'UK'; // make "UK" ambiguous (uk and us)
    state.pendingNationOps = [{ kind: 'rename', nationRef: 'UK', to: 'Empire' }];
    const next = confirmNationOp(state, 0);
    expect(next).not.toBeNull();
    expect(next!.nations.uk.name).toBe('UK'); // neither nation was renamed
    expect(next!.nations.us.name).toBe('UK');
    expect(next!.pendingNationOps).toEqual([]);
  });
});

describe('buildSystemPrompt (nationOps contract, v0.23 #16 P4a; v0.24 #16 P4b)', () => {
  it('both modes contract the nationOps field with all three op kinds and the proposal rule', () => {
    for (const p of [buildSystemPrompt(preset), buildSystemPrompt(preset, true)]) {
      // the JSON shape carries all three kinds in both modes
      expect(p).toMatch(/"kind":"rename","nationRef":"<nation id or name>","to":"<new name>"/);
      expect(p).toMatch(/"kind":"split","nationRef":"<nation id or name>","parts":\[\{"name":"<new name>","territory":\["<region key>"\]\}\]/);
      expect(p).toMatch(/"kind":"merge","nationRefs":\["<id>","<id>"\],"survivingRef":"<id of the surviving nation>","into":"<new name>"/);
      // the rule explains that ops are proposals only the player can confirm
      expect(p).toMatch(/PROPOSAL/);
      expect(p).toMatch(/only take effect if the player confirms/);
      // and the split/merge shapes are spelt out in the hard constraints
      expect(p).toMatch(/at least 2 parts/);
      expect(p).toMatch(/survivingRef" must name one of them/);
    }
  });
});

describe('freshNationId (v0.24 #16 P4b)', () => {
  it('returns the first free of n1, n2, ... against the taken set', () => {
    expect(freshNationId(new Set())).toBe('n1');
    expect(freshNationId(new Set(['n1']))).toBe('n2');
    expect(freshNationId(new Set(['n1', 'n2', 'n3']))).toBe('n4');
    // non-n ids never collide: existing nation ids are irrelevant
    expect(freshNationId(new Set(['uk', 'de', 'us']))).toBe('n1');
  });
});

describe('applyNationOp (split, v0.24 #16 P4b)', () => {
  /** de owns four regions; the player is uk (so a split of de does not move the pointer). */
  function splitState(): GameState {
    const s = baseState();
    s.nations.de.territory = ['DEU-N', 'DEU-S', 'DEU-E', 'DEU-W'];
    s.nations.de.relations = { uk: 'ally' };
    s.nations.uk.relations.de = 'hostile'; // mirror entry, to check the cleanup
    return s;
  }

  it('partitions the parent territory: first-wins per key, leftovers to part 0, fresh ids, baseline stats, copied relations, parent removed', () => {
    const state = splitState();
    applyNationOp(state, {
      kind: 'split',
      nationRef: 'de',
      parts: [
        { name: 'East', territory: ['DEU-E', 'DEU-W', 'ZZZ-not-a-key'] },
        { name: 'West', territory: ['DEU-W', 'DEU-S'] },
      ],
    });
    // the parent is gone and two fresh nations exist (n1, n2 — uk/us/de were taken)
    expect(state.nations.de).toBeUndefined();
    expect(Object.keys(state.nations).sort()).toEqual(['n1', 'n2', 'uk', 'us']);
    const east = state.nations.n1;
    const west = state.nations.n2;
    // East claimed DEU-E and DEU-W first (the invalid key is ignored); the
    // only key no part claimed — DEU-N (DEU-S went to West) — goes to part 0
    // in the parent's territory order.
    expect(east.territory).toEqual(['DEU-E', 'DEU-W', 'DEU-N']);
    // West's DEU-W was already claimed by East; it keeps only DEU-S.
    expect(west.territory).toEqual(['DEU-S']);
    // every parent key sits in exactly one part (sole ownership, nothing lost)
    const all = [...east.territory, ...west.territory].sort();
    expect(all).toEqual(['DEU-E', 'DEU-N', 'DEU-S', 'DEU-W']);
    // fresh baseline stats (not the parent's) and inherited form of state
    expect(east.stats).toEqual(NEW_NATION_STATS);
    expect(west.stats).toEqual(NEW_NATION_STATS);
    expect(east.type).toBe('major');
    expect(west.type).toBe('major');
    // both parts copied the parent's relations
    expect(east.relations).toEqual({ uk: 'ally' });
    expect(west.relations).toEqual({ uk: 'ally' });
    // the mirror entry for the removed parent is cleaned up
    expect(state.nations.uk.relations.de).toBeUndefined();
    expect(state.nations.uk.relations.us).toBe('neutral'); // other entries untouched
    // the player (uk) is not affected
    expect(state.playerNationId).toBe('uk');
  });

  it('an unresolvable nationRef is a no-op (the world is untouched, never throws)', () => {
    const state = splitState();
    const before = JSON.parse(JSON.stringify(state));
    applyNationOp(state, {
      kind: 'split',
      nationRef: 'zzz-not-a-nation',
      parts: [{ name: 'East' }, { name: 'West' }],
    });
    expect(state).toEqual(before);
  });

  it('a split named by the parent NAME works (ref resolution, not just id)', () => {
    const state = splitState();
    applyNationOp(state, {
      kind: 'split',
      nationRef: 'DE', // the name; the id is 'de'
      parts: [{ name: 'East', territory: ['DEU-E'] }, { name: 'West', territory: ['DEU-W'] }],
    });
    expect(state.nations.de).toBeUndefined();
    expect(state.nations.n1.name).toBe('East');
    expect(state.nations.n2.name).toBe('West');
  });

  it('when the parent is the player nation, playerNationId moves to the chosen part (edits.playerPart: default 0, clamped in range)', () => {
    const state = splitState();
    state.playerNationId = 'de';
    applyNationOp(state, {
      kind: 'split',
      nationRef: 'de',
      parts: [{ name: 'East' }, { name: 'West' }, { name: 'Centre' }],
    });
    expect(state.playerNationId).toBe('n1'); // default: the first part

    const state2 = splitState();
    state2.playerNationId = 'de';
    applyNationOp(
      state2,
      {
        kind: 'split',
        nationRef: 'de',
        parts: [{ name: 'East' }, { name: 'West' }, { name: 'Centre' }],
      },
      { playerPart: 1 },
    );
    expect(state2.playerNationId).toBe('n2');

    const state3 = splitState();
    state3.playerNationId = 'de';
    applyNationOp(
      state3,
      {
        kind: 'split',
        nationRef: 'de',
        parts: [{ name: 'East' }, { name: 'West' }],
      },
      { playerPart: 99 }, // clamped down to the last part
    );
    expect(state3.playerNationId).toBe('n2');

    const state4 = splitState();
    state4.playerNationId = 'de';
    applyNationOp(
      state4,
      {
        kind: 'split',
        nationRef: 'de',
        parts: [{ name: 'East' }, { name: 'West' }],
      },
      { playerPart: -5 }, // clamped up to the first part
    );
    expect(state4.playerNationId).toBe('n1');
  });

  it('edits.name renames the chosen part (edits.playerPart picks which one)', () => {
    const state = splitState();
    applyNationOp(
      state,
      {
        kind: 'split',
        nationRef: 'de',
        parts: [{ name: 'East' }, { name: 'West' }],
      },
      { playerPart: 1, name: 'New West' },
    );
    expect(state.nations.n1.name).toBe('East'); // untouched part keeps its name
    expect(state.nations.n2.name).toBe('New West');

    const state2 = splitState();
    applyNationOp(
      state2,
      {
        kind: 'split',
        nationRef: 'de',
        parts: [{ name: 'East' }, { name: 'West' }],
      },
      { name: 'First of the Remnant' }, // no playerPart -> the first part
    );
    expect(state2.nations.n1.name).toBe('First of the Remnant');
    expect(state2.nations.n2.name).toBe('West');
  });

  it('a 1-part split is a no-op on the world (fewer than 2 parts)', () => {
    const state = splitState();
    const before = JSON.parse(JSON.stringify(state));
    applyNationOp(state, { kind: 'split', nationRef: 'de', parts: [{ name: 'East' }] });
    expect(state).toEqual(before);
  });
});

describe('applyNationOp (merge, v0.24 #16 P4b)', () => {
  /**
   * de and us will be merged (the survivor is us — deliberately listed
   * second in nationRefs, so the "survivor's view wins" rule can be observed
   * overwriting the first input's views). uk, fr and ja survive as third
   * parties; the survivor has no view on ja, so ja must come from the first
   * input's map.
   */
  function mergeState(): GameState {
    const s = baseState();
    s.nations.de.relations = { us: 'rival', uk: 'hostile', fr: 'rival', ja: 'rival' };
    s.nations.us.relations = { de: 'ally', uk: 'ally', fr: 'neutral' }; // no view on ja
    s.nations.uk.relations = { us: 'ally', de: 'hostile', fr: 'neutral', ja: 'neutral' };
    s.nations.fr = {
      id: 'fr',
      type: 'major',
      name: 'FR',
      stats: { military: 40, economy: 60, stability: 70, population: 60 },
      territory: ['FRA'],
      relations: { us: 'neutral', de: 'rival', uk: 'neutral', ja: 'neutral' },
    };
    s.nations.ja = {
      id: 'ja',
      type: 'major',
      name: 'JA',
      stats: { military: 30, economy: 80, stability: 50, population: 90 },
      territory: ['JPN'],
      relations: { us: 'neutral', de: 'rival', uk: 'neutral', fr: 'neutral' },
    };
    return s;
  }

  it('folds the inputs into the survivor: union territory (survivor first), survivor stats, survivor view wins per third party (else first input), non-input third parties kept, removed ids dropped from everyone else, into-name', () => {
    const state = mergeState();
    applyNationOp(state, { kind: 'merge', nationRefs: ['de', 'us'], survivingRef: 'us', into: 'Union' });
    // the removed input is gone; the survivor and all non-inputs survive
    expect(state.nations.de).toBeUndefined();
    expect(Object.keys(state.nations).sort()).toEqual(['fr', 'ja', 'uk', 'us']);
    // the survivor keeps its id, its own stats, and the merged name
    expect(state.nations.us.id).toBe('us');
    expect(state.nations.us.stats).toEqual({ military: 60, economy: 90, stability: 80, population: 80 });
    expect(state.nations.us.name).toBe('Union');
    // territory: the union — the survivor's keys first, then the other input's
    expect(state.nations.us.territory).toEqual(['USA', 'DEU']);
    // relations: on uk and fr the survivor's own views (ally/neutral) beat the
    // first input's (hostile/rival); ja has no survivor view, so the first
    // input's (rival) stands; the removed input's id is gone from the map.
    expect(state.nations.us.relations).toEqual({ uk: 'ally', fr: 'neutral', ja: 'rival' });
    // the removed id is dropped from every remaining nation's relations map
    expect(state.nations.uk.relations).toEqual({ us: 'ally', fr: 'neutral', ja: 'neutral' });
    expect(state.nations.fr.relations).toEqual({ us: 'neutral', uk: 'neutral', ja: 'neutral' });
    expect(state.nations.ja.relations).toEqual({ us: 'neutral', uk: 'neutral', fr: 'neutral' });
    // the player (uk) is not part of the merge — the pointer stays valid
    expect(state.playerNationId).toBe('uk');
  });

  it('the player pointer moves to the survivor when the player led a removed input', () => {
    const state = mergeState();
    state.playerNationId = 'de'; // the player's nation is absorbed
    applyNationOp(state, { kind: 'merge', nationRefs: ['de', 'us'], survivingRef: 'us', into: 'Union' });
    expect(state.playerNationId).toBe('us');
    expect(state.nations[state.playerNationId].name).toBe('Union');
  });

  it('edits.name overrides the merged name; an empty edit falls back to "into", then to the survivor name', () => {
    const state = mergeState();
    applyNationOp(state, { kind: 'merge', nationRefs: ['de', 'us'], survivingRef: 'us', into: 'Union' }, { name: 'United World' });
    expect(state.nations.us.name).toBe('United World');

    const state2 = mergeState();
    applyNationOp(state2, { kind: 'merge', nationRefs: ['de', 'us'], survivingRef: 'us', into: 'Union' }, { name: '   ' });
    expect(state2.nations.us.name).toBe('Union');

    const state3 = mergeState();
    applyNationOp(state3, { kind: 'merge', nationRefs: ['de', 'us'], survivingRef: 'us', into: '' }); // empty into: keep the survivor's name
    expect(state3.nations.us.name).toBe('US');
  });

  it('an unresolvable input ref is a no-op (never throws, world untouched)', () => {
    const state = mergeState();
    const before = JSON.parse(JSON.stringify(state));
    applyNationOp(state, {
      kind: 'merge',
      nationRefs: ['us', 'zzz-not-a-nation'],
      survivingRef: 'uk',
      into: 'X',
    });
    expect(state).toEqual(before);
  });

  it('a survivor that is not one of the inputs is a no-op', () => {
    const state = mergeState();
    const before = JSON.parse(JSON.stringify(state));
    applyNationOp(state, {
      kind: 'merge',
      nationRefs: ['us', 'de'],
      survivingRef: 'uk', // uk is not an input
      into: 'X',
    });
    expect(state).toEqual(before);
  });

  it('fewer than two DISTINCT inputs is a no-op (the same nation named twice)', () => {
    const state = mergeState();
    const before = JSON.parse(JSON.stringify(state));
    applyNationOp(state, {
      kind: 'merge',
      nationRefs: ['us', 'US'], // both resolve to 'us'
      survivingRef: 'us',
      into: 'X',
    });
    expect(state).toEqual(before);
  });
});

describe('parseTurnResult', () => {
  it('parses a fenced JSON block', () => {
    const r = parseTurnResult('```json\n{"date":"1939-09-03","events":[{"nation":"uk","type":"military","title":"t","text":"b","outcome":"success"}]}\n```');
    expect(r?.events[0].title).toBe('t');
  });

  it('parses JSON prefixed by leading whitespace/newlines (reasoning model emits "\\n\\n{...}")', () => {
    const r = parseTurnResult('\n\n{"date":"1939-09-03","events":[{"nation":"uk","type":"military","title":"t","text":"b","outcome":"success"}]}\n');
    expect(r?.events[0].title).toBe('t');
    expect(r?.date).toBe('1939-09-03');
  });

  it('extracts the object from surrounding prose', () => {
    const r = parseTurnResult('Sure! Here is the result: {"date":"1939-09-03","events":[]} hope that helps');
    expect(r).not.toBeNull();
  });

  it('returns null for non-JSON output', () => {
    expect(parseTurnResult('no json here at all')).toBeNull();
  });

  it('validateTurnResult ignores unknown/invalid entries and clamps', () => {
    const r = validateTurnResult({
      date: '1939-09-03',
      events: [
        { nation: 'uk', type: 'bogus', title: 't', text: 'b', outcome: 'weird' },
        { nation: 'uk', title: 'missing text' },
      ],
      stateChanges: [
        { nation: 'uk', stat: 'notastat', op: 'set', value: 5 },
        { nation: 'uk', stat: 'military', op: 'set', value: 150 },
      ],
    });
    expect(r).not.toBeNull();
    expect(r!.events).toHaveLength(1); // the invalid one was dropped
    expect(r!.events[0].type).toBe('political'); // bogus type -> default
    expect(r!.events[0].outcome).toBe('neutral'); // bogus outcome -> default
    expect(r!.stateChanges).toHaveLength(1);
    expect(r!.stateChanges[0].value).toBe(100); // clamped
  });
});

describe('applyTurnResult', () => {
  it('does not mutate its input', () => {
    const state = baseState();
    const snapshot = JSON.stringify(state);
    const result: TurnResult = {
      date: '1939-09-03',
      events: [{ nation: 'uk', type: 'military', title: 't', text: 'b', outcome: 'success' }],
      stateChanges: [{ nation: 'uk', stat: 'military', op: 'set', value: 99 }],
      relations: [],
      territoryChanges: [],
      unowned: [],
      nationOps: [], markers: { add: [], remove: [] },
    };
    applyTurnResult(state, result);
    expect(JSON.stringify(state)).toBe(snapshot);
  });

  it('clears the pending round on commit and bumps the version', () => {
    const state = baseState();
    state.pending = [{ kind: 'action', text: 'x' }];
    const result: TurnResult = {
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: [],
      nationOps: [], markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result);
    expect(next.pending).toEqual([]);
    expect(next.version).toBe(2);
    expect(state.pending).toHaveLength(1); // original untouched
    expect(state.version).toBe(1);
  });

  it('with a validKeys set: applies real region keys, ignores hallucinated ones', () => {
    const state = baseState();
    // give the fixture's uk a real key ('wales-bbbb') for DE to be able to take
    state.nations.uk.territory = ['GBR', 'wales-bbbb'];
    const result: TurnResult = {
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      // 'wales-bbbb' is a real key (owned by uk in the fixture); 'not-a-region-xyz'
      // 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: [], 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
    expect(next.nations.de.territory).toContain('wales-bbbb');
    expect(next.nations.uk.territory).not.toContain('wales-bbbb');
    // the bogus key never entered any nation's territory
    for (const n of Object.values(next.nations)) {
      expect(n.territory).not.toContain('not-a-region-xyz');
    }
  });

  it('without a validKeys set: applies every listed key (legacy/unit path)', () => {
    const state = baseState();
    state.nations.uk.territory = ['GBR', 'wales-bbbb'];
    const result: TurnResult = {
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      // 'wales-bbbb' has a sole previous owner (uk) -> it transfers; 'POL' is
      // owned by no one -> a re-claim (v0.22, #16 P3): DE gains it. It was never
      // released (not in state.unowned), so it does not enter GameState.unowned.
      territoryChanges: [{ nation: 'de', gain: ['POL', 'wales-bbbb'], lose: [] }],
      unowned: [],
      nationOps: [], markers: { add: [], remove: [] },
    };
    const next = applyTurnResult(state, result); // no validKeys -> nothing filtered
    expect(next.nations.de.territory).toContain('wales-bbbb');
    expect(next.nations.uk.territory).not.toContain('wales-bbbb');
    expect(next.nations.de.territory).toContain('POL'); // re-claimed, not ignored
    expect(next.unowned).toEqual([]); // never released -> not no man's land
  });
});

describe('applyTurnResult (sole-ownership invariants, v0.21 #16 P2)', () => {
  const noEvents = {
    date: '1939-09-03',
    events: [],
    stateChanges: [],
    relations: [],
    unowned: [],
    nationOps: [], markers: { add: [], remove: [] },
  };

  it('a double claim (two different gainers, one key) is rejected: the key stays with its original owner', () => {
    const state = baseState();
    state.nations.uk.territory = ['GBR', 'wales-bbbb'];
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [
        { nation: 'de', gain: ['wales-bbbb'], lose: [] },
        { nation: 'us', gain: ['wales-bbbb'], lose: [] },
      ],
    });
    expect(next.nations.uk.territory).toContain('wales-bbbb');
    expect(next.nations.de.territory).not.toContain('wales-bbbb');
    expect(next.nations.us.territory).not.toContain('wales-bbbb');
  });

  it('duplicate gain entries for the SAME nation are deduped (one claim, one copy)', () => {
    const state = baseState();
    state.nations.uk.territory = ['GBR', 'wales-bbbb'];
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [
        { nation: 'de', gain: ['wales-bbbb'], lose: [] },
        { nation: 'de', gain: ['wales-bbbb'], lose: [] },
      ],
    });
    expect(next.nations.de.territory.filter((k) => k === 'wales-bbbb')).toHaveLength(1);
    expect(next.nations.uk.territory).not.toContain('wales-bbbb');
  });

  it('a lone "lose" is a no-op: the key cannot be orphaned (zero owners)', () => {
    const state = baseState();
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [{ nation: 'uk', gain: [], lose: ['GBR'] }],
    });
    expect(next.nations.uk.territory).toContain('GBR');
  });

  it('a self-gain is a no-op (a nation keeps exactly one copy of its own key)', () => {
    const state = baseState();
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [{ nation: 'uk', gain: ['GBR'], lose: [] }],
    });
    expect(next.nations.uk.territory.filter((k) => k === 'GBR')).toHaveLength(1);
  });

  it('a pre-existing double ownership is never touched (a key with 2 owners keeps 2)', () => {
    const state = baseState();
    state.nations.us.territory = ['USA', 'GBR']; // uk AND us already share GBR
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [{ nation: 'de', gain: ['GBR'], lose: [] }],
    });
    expect(next.nations.uk.territory).toContain('GBR');
    expect(next.nations.us.territory).toContain('GBR');
    expect(next.nations.de.territory).not.toContain('GBR');
  });

  it('ownership is conserved across a transfer: exactly one owner before and after', () => {
    const state = baseState();
    state.nations.uk.territory = ['GBR', 'wales-bbbb'];
    const count = (s: GameState) =>
      Object.values(s.nations).reduce(
        (acc, n) => acc + n.territory.filter((k) => k === 'wales-bbbb').length,
        0,
      );
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [{ nation: 'de', gain: ['wales-bbbb'], lose: [] }],
    });
    expect(count(state)).toBe(1);
    expect(count(next)).toBe(1);
    expect(next.nations.de.territory).toContain('wales-bbbb');
    expect(next.nations.uk.territory).not.toContain('wales-bbbb');
  });
});

describe('applyTurnResult (no man\'s land, v0.22 #16 P3)', () => {
  const noEvents = {
    date: '1939-09-03',
    events: [],
    stateChanges: [],
    relations: [],
    territoryChanges: [],
    unowned: [],
    nationOps: [], markers: { add: [], remove: [] },
  };

  it('a release removes the key from its sole owner and marks it in GameState.unowned', () => {
    const state = baseState();
    const next = applyTurnResult(state, { ...noEvents, unowned: ['GBR'] });
    expect(next.nations.uk.territory).not.toContain('GBR');
    expect(next.unowned).toEqual(['GBR']);
    // nothing else moved
    expect(next.nations.us.territory).toEqual(['USA']);
    expect(next.nations.de.territory).toEqual(['DEU']);
  });

  it('a re-claim (a gain on a currently-unowned key) grants it and removes it from GameState.unowned', () => {
    const state = baseState();
    state.unowned = ['POL']; // released in an earlier turn
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [{ nation: 'de', gain: ['POL'], lose: [] }],
    });
    expect(next.nations.de.territory).toContain('POL');
    expect(next.unowned).toEqual([]); // it left no man's land
  });

  it('a release and a claim of the same key in one turn: the claim wins (the key is owned)', () => {
    const state = baseState();
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [{ nation: 'de', gain: ['GBR'], lose: [] }],
      unowned: ['GBR'],
    });
    expect(next.nations.de.territory).toContain('GBR');
    expect(next.nations.uk.territory).not.toContain('GBR');
    expect(next.unowned).toEqual([]);
  });

  it('a double claim on a released key is rejected: the key stays in no man\'s land', () => {
    const state = baseState();
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [
        { nation: 'de', gain: ['GBR'], lose: [] },
        { nation: 'us', gain: ['GBR'], lose: [] },
      ],
      unowned: ['GBR'], // released first, then both nations lunge for it
    });
    expect(next.nations.uk.territory).not.toContain('GBR'); // the release applied
    expect(next.nations.de.territory).not.toContain('GBR'); // both claims rejected
    expect(next.nations.us.territory).not.toContain('GBR');
    expect(next.unowned).toEqual(['GBR']);
  });

  it('releasing a key no nation owns (a preset-unassigned region) is a no-op — no man\'s land can only arise from a real release', () => {
    const state = baseState();
    const next = applyTurnResult(state, { ...noEvents, unowned: ['POL'] });
    expect(next.unowned).toEqual([]);
    for (const n of Object.values(next.nations)) expect(n.territory).not.toContain('POL');
  });

  it('releasing a key with two owners (a corrupt state) is a no-op', () => {
    const state = baseState();
    state.nations.us.territory = ['USA', 'GBR']; // uk AND us share GBR
    const next = applyTurnResult(state, { ...noEvents, unowned: ['GBR'] });
    expect(next.nations.uk.territory).toContain('GBR');
    expect(next.nations.us.territory).toContain('GBR');
    expect(next.unowned).toEqual([]);
  });

  it('releasing a key already in no man\'s land is a no-op (it stays listed once)', () => {
    const state = baseState();
    state.unowned = ['POL'];
    const next = applyTurnResult(state, { ...noEvents, unowned: ['POL'] });
    expect(next.unowned).toEqual(['POL']);
  });

  it('with a validKeys set: releasing a hallucinated key is a no-op', () => {
    const state = baseState();
    const next = applyTurnResult(state, { ...noEvents, unowned: ['not-a-region-xyz'] }, new Set(['wales-bbbb']));
    expect(next.unowned).toEqual([]);
  });

  it('a legacy state without the unowned field accepts a release (the result carries the field)', () => {
    const state = baseState();
    delete (state as { unowned?: string[] }).unowned; // simulate a pre-v0.22 row
    const next = applyTurnResult(state, { ...noEvents, unowned: ['GBR'] });
    expect(next.unowned).toEqual(['GBR']);
    expect(next.nations.uk.territory).not.toContain('GBR');
  });

  it('a turn with no releases leaves the existing no man\'s land list unchanged', () => {
    const state = baseState();
    state.unowned = ['POL'];
    const next = applyTurnResult(state, {
      ...noEvents,
      territoryChanges: [{ nation: 'de', gain: ['GBR'], lose: [] }],
    });
    expect(next.unowned).toEqual(['POL']);
    expect(next.nations.de.territory).toContain('GBR');
  });

  it('validateTurnResult dedupes and filters the unowned list (trimmed non-empty strings only)', () => {
    const r = validateTurnResult({
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: [' a ', 'a', '', 42, null, ' b '],
    });
    expect(r).not.toBeNull();
    expect(r!.unowned).toEqual(['a', 'b']);
  });

  it('a lone release is meaningful (it survives the retry/nudge path)', () => {
    expect(
      isMeaningful({ date: 'x', events: [], stateChanges: [], relations: [], territoryChanges: [], unowned: ['GBR'], nationOps: [], markers: { add: [], remove: [] } }),
    ).toBe(true);
  });

  it('runTurn applies a release end-to-end: the model narrates it and the key leaves its owner', async () => {
    const original = baseState();
    original.pending = [{ kind: 'action', text: 'Scorch the earth on the retreat' }];
    const releaseJson = JSON.stringify({
      date: '1939-09-05',
      events: [
        {
          nation: 'uk',
          type: 'military',
          title: 'A retreat through the wastelands',
          text: 'The abandoned highlands burn and lie empty.',
          outcome: 'partial',
        },
      ],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: ['GBR'],
    });
    const payloads: string[] = [];
    const client: LlmClient = {
      chat: async (messages) => {
        const user = messages.find((m) => m.role === 'user');
        if (user) payloads.push(user.content as string);
        return releaseJson;
      },
      listModels: async () => [],
    };
    const { state } = await runTurn({ llm: client, preset, state: original, items: original.pending });
    // the event landed and the release applied
    expect(state.events).toHaveLength(1);
    expect(state.events[0].title).toBe('A retreat through the wastelands');
    expect(state.nations.uk.territory).not.toContain('GBR');
    expect(state.unowned).toEqual(['GBR']);
    // on the first turn the model was shown the (empty) no-man's-land list...
    const first = JSON.parse(payloads[0]) as { unowned?: string[] };
    expect(first.unowned).toEqual([]);
    // ...and on the next turn it is shown the released key (so it can re-claim it)
    const next = await runTurn({ llm: client, preset, state, items: [] });
    const second = JSON.parse(payloads[1]) as { unowned?: string[] };
    expect(second.unowned).toEqual(['GBR']);
    // the repeated "release" of an already-unowned key is a no-op
    expect(next.state.unowned).toEqual(['GBR']);
  });
});

describe('makeNeighboursExecutor (v0.21 #16 P2)', () => {
  const getNeighbours = (keys: string[]) => keys.map((k) => `nb-${k}`);

  it('answers getNeighbours with the resolver output', () => {
    const exec = makeNeighboursExecutor(getNeighbours);
    expect(exec('getNeighbours', { regionKeys: ['a', 'b'] })).toBe(
      JSON.stringify({ neighbours: ['nb-a', 'nb-b'] }),
    );
  });

  it('degrades unknown tools, malformed args, and unknown keys without throwing', () => {
    const exec = makeNeighboursExecutor(getNeighbours, new Set(['a']));
    expect(exec('otherTool', {})).toBe(JSON.stringify({ error: 'unknown tool: otherTool' }));
    expect(exec('getNeighbours', { regionKeys: 'not-an-array' })).toBe(
      JSON.stringify({ neighbours: [] }),
    );
    expect(exec('getNeighbours', { regionKeys: ['a', 'zzz-not-valid'] })).toBe(
      JSON.stringify({ neighbours: ['nb-a'] }), // the unknown key is filtered out
    );
  });
});

describe('playerFrontier (v0.21 #16 P2)', () => {
  const adjacency: Record<string, string[]> = {
    GBR: ['DEU', 'USA'],
    GBR2: ['DEU'],
    DEU: ['GBR', 'GBR2', 'USA'],
    USA: ['GBR', 'DEU'],
  };
  const getNeighbours = (keys: string[]) =>
    [...new Set(keys.flatMap((k) => adjacency[k] ?? []))]
      .filter((k) => !keys.includes(k))
      .sort();

  it('is the sorted, deduped set of other-nation keys bordering the player', () => {
    const state = baseState();
    state.nations.uk.territory = ['GBR', 'GBR2']; // the player owns both
    // DEU (de) and USA (us) border the player; deduped and sorted
    expect(playerFrontier(state, getNeighbours)).toEqual(['DEU', 'USA']);
  });

  it('drops candidates the player itself owns (a sloppy resolver may report them)', () => {
    const state = baseState();
    state.nations.uk.territory = ['GBR', 'GBR2'];
    const sloppy = () => ['GBR2', 'DEU'];
    expect(playerFrontier(state, sloppy)).toEqual(['DEU']);
  });

  it('is empty when the player has no territory or no controllable border', () => {
    const empty = baseState();
    empty.nations.uk.territory = [];
    expect(playerFrontier(empty, getNeighbours)).toEqual([]);
    const noBorders = () => [];
    expect(playerFrontier(baseState(), noBorders)).toEqual([]);
  });
});

describe('runTurn (getNeighbours tool path, v0.21 #16 P2)', () => {
  const adjacency: Record<string, string[]> = {
    GBR: ['DEU'],
    DEU: ['GBR', 'USA'],
    USA: ['DEU'],
  };
  const getNeighbours = (keys: string[]) =>
    [...new Set(keys.flatMap((k) => adjacency[k] ?? []))]
      .filter((k) => !keys.includes(k))
      .sort();

  const finalTurn = JSON.stringify({
    date: '1939-09-03',
    events: [
      {
        nation: 'uk',
        type: 'military',
        title: 'The border region falls',
        text: 'UK seizes the contiguous region.',
        outcome: 'success',
      },
    ],
    stateChanges: [],
    relations: [],
    // the player gains its only frontier region (DEU, owned by de)
    territoryChanges: [{ nation: 'uk', gain: ['DEU'], lose: [] }],
  });

  /**
   * A fake LlmClient implementing BOTH chat() and chatWithTools(). The
   * chatWithTools fake plays the model's side of the protocol: it records
   * the initial messages + tools, executes the scripted tool calls through
   * the executor the engine handed it, and returns the final content.
   */
  function toolLlm(final: string, scriptedCalls: Array<{ name: string; args: Record<string, unknown> }>) {
    const seen: {
      firstMessages: WireMessage[];
      tools: ToolDefinition[];
      executorCalls: Array<{ name: string; args: Record<string, unknown>; result: string }>;
      chatCalls: number;
    } = { firstMessages: [], tools: [], executorCalls: [], chatCalls: 0 };
    const client: LlmClient = {
      chat: async (messages) => {
        seen.chatCalls += 1;
        seen.firstMessages = messages as WireMessage[];
        return final;
      },
      listModels: async () => [],
      chatWithTools: async (messages, tools, executeTool) => {
        seen.firstMessages = messages;
        seen.tools = tools;
        for (const call of scriptedCalls) {
          seen.executorCalls.push({ ...call, result: executeTool(call.name, call.args) });
        }
        return final;
      },
    };
    return { client, seen };
  }

  it('uses chatWithTools with the tool, a frontier in the prompt, the wired executor, and applies the transfer', async () => {
    const original = baseState();
    original.pending = [{ kind: 'action', text: 'Seize the border region' }];
    const { client, seen } = toolLlm(finalTurn, [
      { name: 'getNeighbours', args: { regionKeys: ['GBR'] } },
    ]);
    const { state } = await runTurn({
      llm: client,
      preset,
      state: original,
      items: original.pending,
      getNeighbours,
    });

    // the tool was offered and the system prompt advertises it
    expect(seen.tools.map((t) => t.function.name)).toEqual([GET_NEIGHBOURS_TOOL.function.name]);
    const system = seen.firstMessages[0] as { role: 'system'; content: string };
    expect(system.content).toContain('getNeighbours');

    // the user payload carries the player's frontier (DEU: the player's only
    // controllable border, owned by de)
    const user = seen.firstMessages[1] as { role: 'user'; content: string };
    const payload = JSON.parse(user.content) as { frontier?: string[] };
    expect(payload.frontier).toEqual(['DEU']);

    // the executor the engine built answers from the resolver
    expect(seen.executorCalls).toHaveLength(1);
    expect(seen.executorCalls[0].args).toEqual({ regionKeys: ['GBR'] });
    expect(seen.executorCalls[0].result).toBe(JSON.stringify({ neighbours: ['DEU'] }));

    // chat() was never used on the tool path
    expect(seen.chatCalls).toBe(0);

    // the contiguous transfer was applied: uk gains DEU, de loses it
    expect(state.nations.uk.territory).toContain('DEU');
    expect(state.nations.de.territory).not.toContain('DEU');
  });

  it('falls back to plain chat() when the client lacks chatWithTools (no tool; the frontier hint stays in the prompt)', async () => {
    const original = baseState();
    const { client, seen } = toolLlm(validResult, []);
    delete client.chatWithTools; // simulate a minimal client (chat only)
    const { state } = await runTurn({
      llm: client,
      preset,
      state: original,
      items: original.pending,
      getNeighbours,
    });
    expect(seen.chatCalls).toBe(1);
    expect(seen.tools).toEqual([]); // the tool path was never entered
    const system = seen.firstMessages[0] as { content: string };
    expect(system.content).not.toContain('getNeighbours');
    const user = seen.firstMessages[1] as { content: string };
    const payload = JSON.parse(user.content) as { frontier?: string[] };
    // the frontier hint stays (a resolver was given) even without the tool —
    // it also tells the model which borders are realistically contestable
    expect(payload.frontier).toEqual(['DEU']);
    // the canned result still applied (GBR moved uk -> de)
    expect(state.nations.de.territory).toContain('GBR');
    expect(state.nations.uk.territory).not.toContain('GBR');
  });
});

describe('deterministic stub (one contiguous conquest per turn, v0.21 #16 P2)', () => {
  const adjacency: Record<string, string[]> = {
    GBR: ['DEU'],
    DEU: ['GBR', 'USA'],
    USA: ['DEU'],
  };
  const getNeighbours = (keys: string[]) =>
    [...new Set(keys.flatMap((k) => adjacency[k] ?? []))]
      .filter((k) => !keys.includes(k))
      .sort();

  it('transfers the first frontier region to the player (and its owner loses it)', async () => {
    const original = baseState();
    original.pending = [{ kind: 'action', text: 'March on the border region' }];
    const { state } = await runTurn({
      llm: makeStubLlmClient(),
      preset,
      state: original,
      items: original.pending,
      getNeighbours,
    });
    expect(state.nations.uk.territory).toContain('DEU'); // frontier[0]
    expect(state.nations.de.territory).not.toContain('DEU');
    // the rest of the stub behavior is unchanged
    expect(state.turn).toBe(2);
    expect(state.date).toBe('1939-09-03');
    expect(state.nations.uk.stats.military).toBe(85); // clamp(80 + 5)
    expect(state.events).toHaveLength(1);
  });

  it('with an empty frontier (no controllable border, like the UK in wwii-1939): no transfer, the turn still advances', async () => {
    const original = baseState();
    original.pending = [{ kind: 'action', text: 'Hold the line' }];
    const { state } = await runTurn({
      llm: makeStubLlmClient(),
      preset,
      state: original,
      items: original.pending,
      getNeighbours: () => [], // no borders at all
    });
    expect(state.nations.uk.territory).toEqual(['GBR']); // untouched
    expect(state.nations.de.territory).toEqual(['DEU']);
    expect(state.nations.us.territory).toEqual(['USA']);
    expect(state.turn).toBe(2);
    expect(state.events).toHaveLength(1);
  });
});

describe('buildSystemPrompt (tool mode, v0.21 #16 P2)', () => {
  it('mentions the getNeighbours tool and the contiguity rules only when the tool is sent', () => {
    const plain = buildSystemPrompt(preset);
    expect(plain).not.toContain('getNeighbours');
    expect(plain).toMatch(/Only change borders when war/i); // the legacy rule stays
    const withTool = buildSystemPrompt(preset, true);
    expect(withTool).toContain('getNeighbours');
    expect(withTool).toMatch(/contiguous/i);
    expect(withTool).toMatch(/frontier/i);
    expect(withTool).not.toMatch(/Only change borders when war/i);
  });

  it('(v0.22 #16 P3) both modes contract the no-man\'s-land field (release + re-claim) and constrain it to owned keys', () => {
    for (const p of [buildSystemPrompt(preset), buildSystemPrompt(preset, true)]) {
      // the JSON shape carries the field in both modes
      expect(p).toMatch(/"unowned": \["<region key>"\]/);
      // the rule explains release (narrated in events) and re-claim (ordinary gain)
      expect(p).toMatch(/no man's land/i);
      expect(p).toMatch(/narrate the cause in "events"/);
      expect(p).toMatch(/re-claims it with a "gain"/i);
      // the hard constraint: only currently-owned keys may be released
      expect(p).toMatch(/only region keys that a nation currently owns/);
    }
  });
});

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: [], relations: [], territoryChanges: [], unowned: [], nationOps: [], markers: { add: [], remove: [] } })).toBe(true);
    expect(isMeaningful({ date: 'x', events: [], stateChanges: [{ nation: 'uk', stat: 'military', op: 'set', value: 5 }], relations: [], territoryChanges: [], unowned: [], nationOps: [], markers: { add: [], remove: [] } })).toBe(true);
    expect(isMeaningful({ date: 'x', events: [], stateChanges: [], relations: [], territoryChanges: [], unowned: [], nationOps: [], 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)', () => {
    expect(
      isMeaningful({
        date: 'x',
        events: [],
        stateChanges: [],
        relations: [],
        territoryChanges: [],
        unowned: [],
        nationOps: [{ kind: 'rename', nationRef: 'de', to: 'Reich' }], markers: { add: [], remove: [] },
      }),
    ).toBe(true);
  });

  it('(v0.27 #44) a turn that only adds a marker is meaningful (it survives the retry/nudge path)', () => {
    expect(
      isMeaningful({
        date: 'x',
        events: [],
        stateChanges: [],
        relations: [],
        territoryChanges: [],
        unowned: [],
        nationOps: [],
        markers: { add: [{ type: 'city', name: 'Lyon', regionKey: 'rhone-rhne' }], remove: [] },
      }),
    ).toBe(true);
  });
});

describe('markers (point placement, v0.27 #44)', () => {
  // a deterministic centroid for one region key, undefined for everything else
  const centroidOf = (key: string) =>
    key === 'moselle-rygy' ? { lat: 48, lon: 6, spread: 1 } : undefined;

  // build a MarkerSpec from a (possibly invalid, for the guard tests) type string
  const mk = (type: string, name: string, regionKey: string): MarkerSpec =>
    ({ type: type as MarkerType, name, regionKey });

  it('adds a valid marker with a stable id, a jittered position within the spread, the region owner, and the placed turn', () => {
    const state = baseState();
    state.turn = 4; // placedTurn should equal the resolved turn
    state.nations.uk.territory = ['GBR', 'moselle-rygy']; // the region is owned by uk
    const result: TurnResult = {
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: [],
      nationOps: [],
      markers: { add: [mk('city', 'Strasbourg', 'moselle-rygy')], remove: [] },
    };
    const next = applyTurnResult(state, result, undefined, centroidOf);
    expect(next.markers).toHaveLength(1);
    const m = next.markers[0];
    expect(m.id).toBe(markerId('city', 'Strasbourg', 'moselle-rygy'));
    expect(m.type).toBe('city');
    expect(m.name).toBe('Strasbourg');
    expect(m.regionKey).toBe('moselle-rygy');
    expect(m.ownerNationId).toBe('uk'); // the region's sole owner
    expect(m.placedTurn).toBe(4);
    // the position is the centroid jittered within ±spread/2
    expect(m.lat).toBeGreaterThanOrEqual(47.5);
    expect(m.lat).toBeLessThanOrEqual(48.5);
    expect(m.lon).toBeGreaterThanOrEqual(5.5);
    expect(m.lon).toBeLessThanOrEqual(6.5);
  });

  it('is idempotent: re-adding the same (type, name, regionKey) does not duplicate the marker', () => {
    const state = baseState();
    state.nations.uk.territory = ['moselle-rygy'];
    const add = [mk('city', 'Strasbourg', 'moselle-rygy')];
    const first = applyTurnResult(state, {
      date: '1939-09-03', events: [], stateChanges: [], relations: [], territoryChanges: [],
      unowned: [], nationOps: [], 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: [], relations: [], territoryChanges: [],
      unowned: [], nationOps: [], 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
  });

  it('applyTurnResult drops a new add whose region is unknown or has no centroid, but keeps a valid one', () => {
    const state = baseState();
    state.nations.uk.territory = ['moselle-rygy'];
    // validKeys knows two keys; the centroid resolves only the first.
    const validKeys = new Set(['moselle-rygy', 'other-key']);
    const centroidOf2 = (k: string) =>
      k === 'moselle-rygy' ? { lat: 48, lon: 6, spread: 1 } : undefined;
    const result: TurnResult = {
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: [],
      nationOps: [],
      markers: {
        add: [
          { type: 'city', name: 'Good', regionKey: 'moselle-rygy' }, // valid + centroid → kept
          { type: 'city', name: 'NoCent', regionKey: 'other-key' }, // in validKeys, no centroid → dropped
          { type: 'city', name: 'Unknown', regionKey: 'zzz-not-a-key' }, // not in validKeys → dropped
        ],
        remove: [],
      },
    };
    const next = applyTurnResult(state, result, validKeys, centroidOf2);
    expect(next.markers).toHaveLength(1);
    expect(next.markers[0].name).toBe('Good');
  });

  it('caps the total marker count at MAX_MARKERS, dropping the newest add that exceeds the cap', () => {
    const state = baseState();
    // pre-seed the state with MAX_MARKERS - 1 distinct markers
    const seeded: typeof state.markers = [];
    for (let i = 0; i < MAX_MARKERS - 1; i++) {
      const k = `seed-${i}`;
      seeded.push({
        id: markerId('city', `S${i}`, k),
        type: 'city',
        name: `S${i}`,
        regionKey: k,
        lat: 0, lon: 0,
        ownerNationId: null,
        placedTurn: 1,
      });
    }
    state.markers = seeded;
    // a permissive centroid: every region key resolves
    const anyCentroid = () => ({ lat: 0, lon: 0, spread: 0 });
    const result: TurnResult = {
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [],
      unowned: [],
      nationOps: [],
      markers: {
        add: [
          { type: 'city', name: 'NewA', regionKey: 'new-a' },
          { type: 'city', name: 'NewB', regionKey: 'new-b' },
        ],
        remove: [],
      },
    };
    const next = applyTurnResult(state, result, undefined, anyCentroid);
    expect(next.markers).toHaveLength(MAX_MARKERS); // capped, not MAX_MARKERS + 1
    expect(next.markers.some((m) => m.name === 'NewA')).toBe(true); // the 1st new one kept
    expect(next.markers.some((m) => m.name === 'NewB')).toBe(false); // the 2nd (over cap) dropped
  });

  it('removes a marker by id; removing an absent id is a no-op', () => {
    const state = baseState();
    state.nations.uk.territory = ['moselle-rygy'];
    const idA = markerId('city', 'Strasbourg', 'moselle-rygy');
    const idB = markerId('port', 'Dunkirk', 'moselle-rygy');
    state.markers = [
      { id: idA, type: 'city', name: 'Strasbourg', regionKey: 'moselle-rygy', lat: 48, lon: 6, ownerNationId: 'uk', placedTurn: 1 },
      { id: idB, type: 'port', name: 'Dunkirk', regionKey: 'moselle-rygy', lat: 48, lon: 6, ownerNationId: 'uk', placedTurn: 1 },
    ];
    const next = applyTurnResult(state, {
      date: '1939-09-03', events: [], stateChanges: [], relations: [], territoryChanges: [],
      unowned: [], nationOps: [], 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
  });

  it('a marker owner follows its region: released to no man\'s land → null; re-claimed → the new owner', () => {
    const state = baseState();
    state.nations.uk.territory = ['moselle-rygy'];
    const idA = markerId('city', 'Strasbourg', 'moselle-rygy');
    state.markers = [
      { id: idA, type: 'city', name: 'Strasbourg', regionKey: 'moselle-rygy', lat: 48, lon: 6, ownerNationId: 'uk', placedTurn: 1 },
    ];
    // 1) uk releases the region → the marker becomes ownerless
    const released = applyTurnResult(state, {
      date: '1939-09-03', events: [], stateChanges: [], relations: [], territoryChanges: [],
      unowned: ['moselle-rygy'], nationOps: [], 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: [], relations: [],
      territoryChanges: [{ nation: 'de', gain: ['moselle-rygy'], lose: [] }],
      unowned: [], nationOps: [], markers: { add: [], remove: [] },
    }, undefined, centroidOf);
    expect(reclaimed.markers[0].ownerNationId).toBe('de');
  });

  it('the user prompt carries the existing markers when provided (and omits the field otherwise)', () => {
    const state = baseState();
    const info = {
      id: markerId('city', 'Strasbourg', 'moselle-rygy'),
      type: 'city' as MarkerType,
      name: 'Strasbourg',
      regionKey: 'moselle-rygy',
      owner: 'uk',
    };
    const payload = JSON.parse(
      buildUserPrompt(state, [], undefined, undefined, undefined, [info]),
    ) as { markers?: Array<Record<string, unknown>> };
    expect(payload.markers).toHaveLength(1);
    expect(payload.markers![0].name).toBe('Strasbourg');
    expect(payload.markers![0].owner).toBe('uk');
    // a bare call (no markers arg) omits the field entirely
    const bare = JSON.parse(buildUserPrompt(state, [])) as { markers?: unknown };
    expect(bare.markers).toBeUndefined();
  });

  it('the system prompt documents the markers contract (field + placement rule + a type)', () => {
    const prompt = buildSystemPrompt(preset);
    expect(prompt).toMatch(/named points on the map/i);
    expect(prompt).toMatch(/"markers"/);
    expect(prompt).toMatch(/"add"/);
    expect(prompt).toMatch(/"remove"/);
    expect(prompt).toMatch(/gathering/);
    expect(prompt).toMatch(/no man's land/); // owner recompute on release
  });

  it('validateMarkerOps cleans a raw markers field: drops bad types/empty names, dedupes, trims removes', () => {
    const raw = {
      add: [
        { type: 'city', name: 'X', regionKey: 'a' },
        { type: 'not-a-type', name: 'Y', regionKey: 'a' }, // invalid type -> dropped
        { type: 'city', name: '   ', regionKey: 'a' }, // empty name -> dropped
        { type: 'city', name: 'X', regionKey: 'a' }, // duplicate (same id) -> deduped
        { type: 'port', name: 'Z', regionKey: 'b' }, // valid
      ],
      remove: ['id-1', 42, '', '  id-2  ', 'id-1'], // number/empty dropped, trimmed, deduped
    };
    const out = validateMarkerOps(raw);
    expect(out.add.map((m) => m.name).sort()).toEqual(['X', 'Z']);
    expect(out.remove).toEqual(['id-1', 'id-2']);
  });

  it('validateMarkerOps returns empty ops for a non-object raw value (a string, an array, null)', () => {
    for (const bad of ['oops', [{ type: 'city', name: 'X', regionKey: 'a' }], null, undefined]) {
      expect(validateMarkerOps(bad)).toEqual({ add: [], remove: [] });
    }
  });

  it('runTurn wires the centroid through: a marker added over the LLM path is placed (owner = region owner)', async () => {
    const result = JSON.stringify({
      date: '1939-09-03',
      events: [],
      stateChanges: [],
      relations: [],
      territoryChanges: [{ nation: 'uk', gain: ['moselle-rygy'], lose: [] }],
      unowned: [],
      nationOps: [],
      markers: { add: [{ type: 'city', name: 'Strasbourg', regionKey: 'moselle-rygy' }], remove: [] },
    });
    const { state } = await runTurn({
      llm: fakeLlm([result]),
      preset,
      state: baseState(),
      items: [],
      centroidOf,
    });
    expect(state.markers).toHaveLength(1);
    expect(state.markers[0].name).toBe('Strasbourg');
    expect(state.markers[0].ownerNationId).toBe('uk'); // uk gained the region this turn
  });
});

// --- Per-region stats (v0.28, #46): the derived-stats model ------------------
//
// A nation's 0–100 stats are DERIVED as the area×population-weighted median of
// the stats of the regions it owns (`GameState.regionStats`). These tests pin
// the turn-level maintenance of that model in `applyTurnResult`:
//   - a transferred region keeps its OWN stats (the conquest is what makes a
//     nation's regions diverge);
//   - a released region's entry is deleted (no man's land carries none);
//   - a re-claimed region with no entry is re-inited to the gainer's stats;
//   - a 0-region nation keeps its (directly-maintained) stats;
//   - the end-of-turn recompute weights by area×population when `geoOf` is
//     provided (and degrades to a uniform median without it).
//
// `applyTurnResult` is used directly (not `runTurn`) so the tests are pure and
// don't depend on the LLM: the result objects below are constructed directly.

const NS = (military: number, economy: number, stability: number, population: number): NationStats => ({
  military,
  economy,
  stability,
  population,
});

const RS = (military: number, economy: number, stability: number, population: number): RegionStats => ({
  military,
  economy,
  stability,
  population,
});

function mkNation(id: string, stats: NationStats, territory: string[]): Nation {
  return { id, name: id.toUpperCase(), type: 'major', stats, territory, relations: {} };
}

function mkTurnState(
  nations: Record<string, Nation>,
  regionStats: Record<string, RegionStats>,
  unowned: string[] = [],
): GameState {
  return {
    id: 'g',
    presetId: 'p',
    presetTitle: 'P',
    playerNationId: Object.keys(nations)[0] ?? '',
    turn: 1,
    date: '1939-09-01',
    nations,
    events: [],
    pending: [],
    version: 1,
    unowned,
    pendingNationOps: [],
    markers: [],
    regionStats,
  };
}

function mkTurnResult(partial: Partial<TurnResult>): TurnResult {
  return {
    date: '1939-09-03',
    events: partial.events ?? [],
    stateChanges: partial.stateChanges ?? [],
    relations: partial.relations ?? [],
    territoryChanges: partial.territoryChanges ?? [],
    unowned: partial.unowned ?? [],
    nationOps: partial.nationOps ?? [],
    markers: partial.markers ?? { add: [], remove: [] },
  };
}

describe('applyTurnResult — per-region stats (v0.28, #46)', () => {
  it('a transferred region keeps its OWN stats; the conqueror\'s aggregate blends them', () => {
    // uk owns g1 (military 80), de owns d1 (military 95). de conquers g1.
    const state = mkTurnState(
      {
        uk: mkNation('uk', NS(80, 70, 60, 50), ['g1']),
        de: mkNation('de', NS(95, 90, 75, 90), ['d1']),
      },
      {
        g1: RS(80, 70, 60, 50),
        d1: RS(95, 90, 75, 90),
      },
    );
    const next = applyTurnResult(
      state,
      mkTurnResult({ territoryChanges: [{ nation: 'de', gain: ['g1'], lose: [] }] }),
    );
    // territory moved
    expect(next.nations.uk.territory).toEqual([]);
    expect(next.nations.de.territory).toEqual(['d1', 'g1']);
    // the transferred region KEPT its own (uk's) stats — not re-inited to de's
    expect(next.regionStats.g1).toEqual(RS(80, 70, 60, 50));
    expect(next.regionStats.d1).toEqual(RS(95, 90, 75, 90));
    // de's derived stats are the (uniform) median of its two regions → pulled
    // toward the conquered region's lower values
    expect(next.nations.de.stats).toEqual(RS(80, 70, 60, 50));
    // uk (now 0 regions) keeps its directly-maintained stats untouched
    expect(next.nations.uk.stats).toEqual(NS(80, 70, 60, 50));
  });

  it('a released region leaves no-man\'s land and its stats entry is deleted', () => {
    const state = mkTurnState(
      { uk: mkNation('uk', NS(80, 70, 60, 50), ['g1', 'g2']) },
      { g1: RS(80, 70, 60, 50), g2: RS(60, 60, 60, 60) },
    );
    const next = applyTurnResult(state, mkTurnResult({ unowned: ['g1'] }));
    expect(next.unowned).toEqual(['g1']);
    expect(next.nations.uk.territory).toEqual(['g2']);
    // g1's stats left the table with the region; g2's stay
    expect(next.regionStats).toEqual({ g2: RS(60, 60, 60, 60) });
    // uk's derived stats now come only from g2
    expect(next.nations.uk.stats).toEqual(RS(60, 60, 60, 60));
  });

  it('a re-claimed region with no entry is re-inited to the gainer\'s current stats', () => {
    // g1 is unowned (released earlier; its stats entry was deleted). de owns d1.
    const deStats = NS(95, 90, 75, 90);
    const state = mkTurnState(
      {
        uk: mkNation('uk', NS(80, 70, 60, 50), []),
        de: mkNation('de', deStats, ['d1']),
      },
      { d1: RS(95, 90, 75, 90) }, // g1 has NO entry (it was released)
      ['g1'],
    );
    const next = applyTurnResult(state, mkTurnResult({ territoryChanges: [{ nation: 'de', gain: ['g1'], lose: [] }] }));
    expect(next.unowned).toEqual([]); // g1 leaves no man's land
    expect(next.nations.de.territory).toEqual(['d1', 'g1']);
    // g1 was re-inited as a copy of de's (pre-stateChanges) stats
    expect(next.regionStats.g1).toEqual(RS(95, 90, 75, 90));
    // both of de's regions now hold identical stats → derived stats = those stats
    expect(next.nations.de.stats).toEqual(RS(95, 90, 75, 90));
  });

  it('a 0-region nation keeps its directly-maintained stats (the recompute skips it)', () => {
    const state = mkTurnState(
      { uk: mkNation('uk', NS(80, 70, 60, 50), []) },
      {},
    );
    const next = applyTurnResult(
      state,
      mkTurnResult({ stateChanges: [{ nation: 'uk', stat: 'military', op: 'set', value: 99 }] }),
    );
    expect(next.nations.uk.territory).toEqual([]);
    // no regions to aggregate → the nation-level update sticks
    expect(next.nations.uk.stats.military).toBe(99);
    expect(next.regionStats).toEqual({});
  });

  it('the recompute weights by area×population: the larger region dominates (geoOf)', () => {
    // uk owns two regions: a small one (military 50) and a large one (military
    // 90). With area×population weighting the large region's value wins; without
    // geo the uniform median picks the lower value (reached first at half-weight).
    const state = mkTurnState(
      { uk: mkNation('uk', NS(50, 50, 50, 50), ['big', 'small']) },
      { big: RS(90, 90, 90, 90), small: RS(50, 50, 50, 50) },
    );
    const geoOf = (k: string) =>
      k === 'big' ? { area: 1000, population: 1000 } : { area: 10, population: 100 };

    const weighted = applyTurnResult(state, mkTurnResult({}), undefined, undefined, geoOf);
    expect(weighted.nations.uk.stats).toEqual(RS(90, 90, 90, 90)); // the large region dominates

    const uniform = applyTurnResult(state, mkTurnResult({})); // no geoOf
    expect(uniform.nations.uk.stats).toEqual(RS(50, 50, 50, 50)); // uniform → lower value first
  });

  it('a nation-level stat change re-applies to every owned region (before the recompute)', () => {
    // uk owns two identical regions. A nation-level `add` applies to each region
    // and the derived (uniform) median tracks it; a 0-region sibling keeps its
    // own nation-level update.
    const state = mkTurnState(
      {
        uk: mkNation('uk', NS(50, 50, 50, 50), ['a', 'b']),
        de: mkNation('de', NS(50, 50, 50, 50), []),
      },
      { a: RS(50, 50, 50, 50), b: RS(50, 50, 50, 50) },
    );
    const next = applyTurnResult(
      state,
      mkTurnResult({
        stateChanges: [
          { nation: 'uk', stat: 'economy', op: 'add', value: 20 },
          { nation: 'de', stat: 'military', op: 'set', value: 77 },
        ],
      }),
    );
    // uk: both regions +20 economy → derived economy 70
    expect(next.regionStats.a).toEqual(RS(50, 70, 50, 50));
    expect(next.regionStats.b).toEqual(RS(50, 70, 50, 50));
    expect(next.nations.uk.stats).toEqual(RS(50, 70, 50, 50));
    // de: 0 regions → its nation-level set sticks
    expect(next.nations.de.stats.military).toBe(77);
  });

  it('the original state is never mutated', () => {
    const state = mkTurnState(
      { uk: mkNation('uk', NS(80, 70, 60, 50), ['g1']), de: mkNation('de', NS(95, 90, 75, 90), ['d1']) },
      { g1: RS(80, 70, 60, 50), d1: RS(95, 90, 75, 90) },
    );
    const beforeNations = JSON.stringify(state.nations);
    const beforeRegions = JSON.stringify(state.regionStats);
    applyTurnResult(state, mkTurnResult({ territoryChanges: [{ nation: 'de', gain: ['g1'], lose: [] }] }));
    expect(JSON.stringify(state.nations)).toBe(beforeNations);
    expect(JSON.stringify(state.regionStats)).toBe(beforeRegions);
  });
});