feat: #66 contested regions / frontlines — 12th ability (v0.44.0)

A third region state (contested frontline): a region in no nation's territory and not in unowned, opened/resolved by the LLM, tied to an active war. Sole-ownership invariant preserved. Durable GameState.contested; contested-inert stub; map legend stays at 7.

server/abilities/contested.ts

@@ -0,0 +1,301 @@
+// The CONTESTED (contested regions / frontlines) ability (v0.44.0, #66) as a
+// modular LLM-ability (v0.40.0, #67) — a THIRD region state, besides "owned by
+// one nation" and "no man's land": a war frontline that is in **no** nation's
+// `territory` and not in `unowned`, contested by two or more nations at war.
+//
+// Each turn the LLM may `open` a region as a contested frontline and/or
+// `resolve` an existing one. `open` requires the region to have a SOLE owner
+// that is at war with at least one of the parties, or to be no man's land (in
+// `unowned`) with two or more of the parties at war with each other; a region
+// with two or more owners, or whose owner is not at war with any party, cannot
+// be contested (dropped). On a successful open the key is removed from its
+// owner's `territory` (sole ownership is preserved — a contested key is in NO
+// territory) and from `unowned`, its `regionStats` entry is deleted, and a
+// `{ regionKey, parties }` entry (parties = resolved nation ids) is added to
+// `GameState.contested` (unique by `regionKey` — re-opening replaces it).
+// `resolve` removes the entry and releases the key to no man's land — UNLESS a
+// concurrent winning claim by one of the parties (allowed by the
+// territory-step guard in engine.ts) already re-owned it, in which case it
+// stays owned and its stats are kept.
+//
+// A still-contested key is NOT a valid normal-claim target: a plain `gain` on
+// it is dropped in the territory step (only a resolving party's claim
+// re-owns it). The layer NEVER moves a key into two territories (sole
+// ownership is sacrosanct), never touches borders directly (the key simply
+// leaves ownership), and is deterministic (no hidden randomness — the LLM
+// declares, the engine applies fixed rules).
+//
+// This is a DURABLE ability (unlike the turn-transient hybrid / disasters /
+// migration layers): it owns the `GameState.contested` field, and the user
+// payload carries the current contested list (only when non-empty).
+
+import { deriveNationStats } from '../../shared/protocol';
+import type { ContestedOps, ContestedRegion } from '../../shared/protocol';
+// The map-fill constants + tooltip label live in the shared protocol module
+// (like the sea-zone / no-man's-land constants); re-exported here so the
+// index / engine re-export surface is one consistent place.
+export {
+  CONTESTED_FILL,
+  CONTESTED_STROKE,
+  contestedTooltipLabel,
+} from '../../shared/protocol';
+import type { GameState } from '../../shared/types';
+import { atWar } from './apply-helpers';
+import { resolveNationRef, resolveRegionKey, str } from './shared';
+import type { Ability, AbilityCtx } from './types';
+
+/**
+ * (v0.44.0, #66) The SOLE owners of a region key in `next` (a key that is in no
+ * nation's `territory` yields `[]`; a corrupt 2+ owner key yields both). Pure.
+ */
+function currentOwners(next: GameState, key: string): string[] {
+  const owners: string[] = [];
+  for (const n of Object.values(next.nations)) {
+    if (n.territory.includes(key)) owners.push(n.id);
+  }
+  return owners;
+}
+
+/**
+ * (v0.44.0, #66) Resolve a region reference (a raw key or a human name) to a
+ * concrete region key: exact key first, then a unique case-insensitive name
+ * match. With no region-key manifest loaded (`validKeys` undefined) the raw
+ * string is accepted as the key (a name cannot be resolved without the
+ * manifest). Returns `null` when the reference is empty or unresolvable.
+ */
+function resolveKey(
+  ref: string,
+  validKeys?: ReadonlySet<string>,
+  nameOf?: (key: string) => string | undefined,
+): string | null {
+  const r = (ref ?? '').trim();
+  if (!r) return null;
+  if (!validKeys) return r; // no manifest: accept the raw key as-is
+  return resolveRegionKey(r, validKeys, nameOf ?? (() => undefined));
+}
+
+/**
+ * (v0.44.0, #66) Resolve a list of party references to distinct nation ids
+ * (id first, then a case-insensitive unique name), preserving first-appearance
+ * order. An unresolvable ref is dropped. Pure.
+ */
+function resolveParties(next: GameState, refs: string[]): string[] {
+  const out: string[] = [];
+  for (const ref of refs) {
+    const id = resolveNationRef(next, ref);
+    if (id && !out.includes(id)) out.push(id);
+  }
+  return out;
+}
+
+/**
+ * (v0.44.0, #66) Re-derive a nation's aggregate `stats` from its regions'
+ * per-region stats, with the same 0-region / no-entry guards as the engine's
+ * main recompute (a nation with no region, or none with a stats entry, keeps
+ * its directly-mutated `stats`). Used after a contested open strips a region
+ * from its owner. Never throws.
+ */
+function rederiveOwnerStats(
+  next: GameState,
+  ownerId: string,
+  geoOf?: (key: string) => { area: number; population: number } | undefined,
+): void {
+  const n = next.nations[ownerId];
+  if (!n) return;
+  if (n.territory.length > 0 && n.territory.some((k) => next.regionStats[k])) {
+    n.stats = deriveNationStats(n.territory, next.regionStats, geoOf);
+  }
+}
+
+/**
+ * (v0.44.0, #66) Validate the raw `contested` field of a turn into a safe
+ * {@link ContestedOps}. Defensive like the rest of the parser — never throws.
+ * `open`: each op needs a non-empty `regionKey` (capped at 120 chars) and
+ * TWO OR MORE non-empty `parties` refs (each capped at 200 chars); an op with
+ * a missing `regionKey` or fewer than two party refs is dropped. `resolve`:
+ * each entry is a non-empty region key (capped at 120 chars); empty / non-
+ * string entries are dropped. Both region keys and party refs are kept RAW
+ * here (like the hybrid / economy / industry refs) — whether a ref resolves to
+ * a real region / nation, and whether the war-linkage / ownership conditions
+ * hold, is checked at apply time (a ref that does not resolve, or a region that
+ * is not contestable, is dropped there). A missing / malformed top-level object
+ * yields `{ open: [], resolve: [] }`.
+ */
+export function validateContestedOps(raw: unknown): ContestedOps {
+  const out: ContestedOps = { open: [], resolve: [] };
+  if (!raw || typeof raw !== 'object' || Array.isArray(raw)) return out;
+  const o = raw as Record<string, unknown>;
+  if (Array.isArray(o.open)) {
+    for (const e of o.open) {
+      if (!e || typeof e !== 'object') continue;
+      const p = e as Record<string, unknown>;
+      const regionKey = str(p.regionKey, 120);
+      if (!regionKey) continue; // missing / empty region key: drop
+      if (!Array.isArray(p.parties)) continue; // missing / malformed parties: drop
+      const parties = p.parties
+        .map((x) => str(x, 200))
+        .filter((x): x is string => x !== null);
+      if (parties.length < 2) continue; // need at least two party refs
+      out.open.push({ regionKey, parties });
+    }
+  }
+  if (Array.isArray(o.resolve)) {
+    for (const e of o.resolve) {
+      const key = str(e, 120);
+      if (key) out.resolve.push(key);
+    }
+  }
+  return out;
+}
+
+/**
+ * (v0.44.0, #66) Apply the turn's contested-region ops to `next`, mutating in
+ * place and never throwing. Runs in the `ABILITIES` loop AFTER the territory
+ * step and the derived-stats recompute, and BEFORE markers / nationOps, so the
+ * owner / unowned / wars it inspects are all final for this turn.
+ *
+ *  (1) RESOLVE (first): each key in `resolve` that is currently contested is
+ *      removed from `next.contested` and released to no man's land (into
+ *      `unowned`, out of any territory, `regionStats` deleted) — UNLESS a
+ *      concurrent winning claim by one of the parties (the only claim the
+ *      territory step permits on a contested key) already re-owned it, in
+ *      which case it stays owned and keeps (or re-inits) its stats.
+ *  (2) OPEN: each op that resolves to a contestable region (a sole owner at
+ *      war with a party, or a no-man's-land region whose parties are at war
+ *      with each other) is moved out of ownership (the owner's territory /
+ *      `unowned`), its `regionStats` is deleted, and it is added to
+ *      `next.contested` (unique by `regionKey` — an open replaces a kept
+ *      entry for the same key). The stripped owner's derived stats are
+ *      re-derived.
+ *
+ * A contested key is never placed into two territories and is never left in
+ * `unowned` (the two states are mutually exclusive), so the sole-ownership
+ * invariant holds after every op.
+ */
+export function applyContested(next: GameState, ops: ContestedOps, ctx: AbilityCtx): void {
+  const validKeys = ctx.validRegionKeys;
+  const nameOf = ctx.regionNameOf;
+  const geoOf = ctx.geoOf;
+  const open = Array.isArray(ops?.open) ? ops.open : [];
+  const resolve = Array.isArray(ops?.resolve) ? ops.resolve : [];
+  const prevContested = Array.isArray(next.contested) ? next.contested : [];
+
+  // (1) RESOLVE first: rebuild the kept list, dropping resolved keys. A
+  // resolved key is released to no man's land unless a party re-owned it.
+  const resolveSet = new Set(resolve);
+  const kept: ContestedRegion[] = [];
+  for (const c of prevContested) {
+    if (!resolveSet.has(c.regionKey)) {
+      kept.push(c); // not resolved this turn: keep
+      continue;
+    }
+    const owners = currentOwners(next, c.regionKey);
+    if (owners.length === 1 && c.parties.includes(owners[0])) {
+      // A party re-owned it via a concurrent winning claim (the territory step
+      // allowed it): keep it owned, ensure it has stats (the claim re-inits an
+      // absent entry; the post-claim recompute already reflected the gain).
+      if (!next.regionStats[c.regionKey]) {
+        next.regionStats[c.regionKey] = { ...next.nations[owners[0]].stats };
+      }
+      continue; // stays owned — not re-added to `contested`
+    }
+    // Release to no man's land: out of any territory (defensive — a contested
+    // key is normally in none), into `unowned`, and its per-region stats leave.
+    for (const n of Object.values(next.nations)) {
+      const i = n.territory.indexOf(c.regionKey);
+      if (i !== -1) n.territory.splice(i, 1);
+    }
+    if (!next.unowned.includes(c.regionKey)) next.unowned.push(c.regionKey);
+    delete next.regionStats[c.regionKey];
+  }
+
+  // (2) OPEN: each op that resolves to a contestable region is moved out of
+  // ownership and added to the contested list (unique by region key).
+  const opened = new Map<string, string[]>(); // region key -> resolved party ids
+  for (const op of open) {
+    const key = resolveKey(op.regionKey, validKeys, nameOf);
+    if (!key) continue;
+    const parties = resolveParties(next, op.parties);
+    if (parties.length < 2) continue; // fewer than two distinct resolved parties
+
+    const owners = currentOwners(next, key);
+    let ok = false;
+    if (owners.length === 1) {
+      // Sole owner present: the owner must be at war with at least one party
+      // (the owner may itself be a party — atWar is false for a==b, so this
+      // checks the owner against the OTHER parties).
+      ok = parties.some((p) => atWar(next.wars, owners[0], p));
+    } else if (owners.length === 0 && next.unowned.includes(key)) {
+      // No owner + no man's land: two of the parties must be at war with
+      // each other.
+      for (let i = 0; i < parties.length && !ok; i++) {
+        for (let j = i + 1; j < parties.length; j++) {
+          if (atWar(next.wars, parties[i], parties[j])) {
+            ok = true;
+            break;
+          }
+        }
+      }
+    }
+    // Two or more owners (corrupt), an owner not at war with any party, or a
+    // not-in-unowned keyless region: never contestable (dropped).
+    if (!ok) continue;
+
+    if (owners.length === 1) {
+      const n = next.nations[owners[0]];
+      const i = n.territory.indexOf(key);
+      if (i !== -1) n.territory.splice(i, 1);
+      rederiveOwnerStats(next, owners[0], geoOf);
+    } else {
+      const i = next.unowned.indexOf(key);
+      if (i !== -1) next.unowned.splice(i, 1);
+    }
+    delete next.regionStats[key];
+    opened.set(key, parties);
+  }
+
+  // Rebuild `next.contested`: the kept (unresolved) entries plus the newly
+  // opened ones, unique by region key (an open replaces a kept entry for the
+  // same key; a resolve removed its key from `kept` above).
+  const final: ContestedRegion[] = [];
+  const seen = new Set<string>();
+  for (const c of kept) {
+    if (opened.has(c.regionKey)) continue; // replaced by a re-open this turn
+    if (seen.has(c.regionKey)) continue; // dedupe (should not happen, but safe)
+    seen.add(c.regionKey);
+    final.push(c);
+  }
+  for (const [key, parties] of opened) {
+    if (seen.has(key)) continue;
+    seen.add(key);
+    final.push({ regionKey: key, parties });
+  }
+  next.contested = final;
+}
+
+export const contested: Ability<'contested'> = {
+  field: 'contested',
+  default: () => ({ open: [], resolve: [] }),
+  validate: (raw) => validateContestedOps(raw),
+  apply: (state, data, ctx) => applyContested(state, data, ctx),
+  schemaLine: () =>
+    '  "contested": {"open":[{"regionKey":"<region key>","parties":["<nation 1>","<nation 2>"]}],"resolve":["<region key>"]},',
+  constraint: () =>
+    '- Contested regions ("contested") are WAR FRONTLINES: a region that no nation controls and that is not no man\'s land, contested by two or more nations at war. An "open" op ({"regionKey":"<key>","parties":["<a>","<b>"]}) makes a region a frontline — it leaves its owner\'s territory (or no-man\'s-land) and is contested: the region\'s sole owner must be at war with at least one of the parties, or (for a no-man\'s-land region) two of the parties must be at war with each other. A "resolve" op (["<key>"]) ends a frontline, releasing the region to no man\'s land — unless a party\'s concurrent claim re-owns it. A contested region is in NO nation\'s territory (never two) and is never no man\'s land while contested. The user message\'s "contested" field lists the current frontlines (region key + party names). Propose at most 1-2 contested-region changes per turn and narrate each one in "events" (a "military" event).',
+  isMeaningful: (data) => data.open.length > 0 || data.resolve.length > 0,
+  stateFields: ['contested'],
+  stub: () => ({ open: [], resolve: [] }),
+  // The user payload carries the current contested frontlines (region key +
+  // party NAMES, resolved from the stored ids) — but only when non-empty (a
+  // fresh / no-frontline world contributes nothing, like the turn-transient
+  // layers).
+  payload: (ctx) => {
+    if (!ctx.contested || ctx.contested.length === 0) return {};
+    return {
+      contested: ctx.contested.map((c) => ({
+        regionKey: c.regionKey,
+        parties: c.parties.map((id) => ctx.state.nations[id]?.name ?? id),
+      })),
+    };
+  },
+};

server/abilities/disasters.test.ts

@@ -72,6 +72,8 @@ function mkState(
     industry: [],
     // (v0.43.0, #65) no sea-zone control on a fresh state.
     seaZones: [],
+    // (v0.44.0, #66) no contested regions on a fresh state.
+    contested: [],
   };
 }
 

server/abilities/goldens/system-no-tool.txt

@@ -42,6 +42,7 @@ Respond with ONLY a valid JSON object of exactly this shape. No prose, no commen
   "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>"}]},
   "migration": {"ops":[{"kind":"<migration|refugees|diaspora|exodus>","from":"<nation id or name>","to":"<nation id or name>","scale":"<small|moderate|large>","detail":"<short detail>"}]},
   "sea": {"control":[{"zone":"<seaZoneId>","by":"<nation id or name>"}]},
+  "contested": {"open":[{"regionKey":"<region key>","parties":["<nation 1>","<nation 2>"]}],"resolve":["<region key>"]},
   "markers": {"add":[{"type":"<city|factory|army|port|capital|fleet|rocket|gathering>","name":"<short name>","regionKey":"<region key>"}],"remove":["<marker id>"]}
 }
 
@@ -70,6 +71,7 @@ HARD CONSTRAINTS
 - 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).
 - Migration & refugees ("migration.ops") are people moving between nations this turn: a "kind" ("migration", "refugees", "diaspora", or "exodus"), a "from" (the source nation — id or name), a "to" (the destination nation — required for every kind except "exodus", which has no destination), and a "scale" (small / moderate / large). The engine applies a DETERMINISTIC effect (no hidden randomness): the source LOSES a small amount of population and economy, the destination GAINS a small amount of population and economy (a "large" influx additionally strains the destination's stability by 2), and the from↔to relation moves one step toward the positive end of the ally/neutral/rival/hostile ladder — capped at "ally" for "refugees" (hosting refugees builds the strongest goodwill), capped at "neutral" for "migration"/"diaspora" (milder ties), and not at all for "exodus"; the nudge never creates or escalates a "war" (a warring pair is left untouched). The layer is turn-transient (no memory): a continuing flow is simply RE-DECLARED each turn it persists. It never moves borders — sole ownership is untouched. Propose at most 1-2 per turn and narrate each one in "events" (a "social" or "diplomatic" event).
 - Sea control ("sea") is the naval layer, fully parallel to but INDEPENDENT of land: each of the 12 fixed sea zones — "north-atlantic" (North Atlantic), "south-atlantic" (South Atlantic), "pacific" (Pacific Ocean), "indian" (Indian Ocean), "mediterranean" (Mediterranean Sea), "north-sea" (North Sea), "baltic" (Baltic Sea), "arctic" (Arctic Ocean), "black-sea" (Black Sea), "gulf-mexico" (Gulf of Mexico), "red-sea" (Red Sea), "sargasso" (Sargasso Sea) — is under the SOLE control of at most one nation. A control op ({"zone":"<id>","by":"<nation>"}) sets or replaces that zone's controller (the user message's "seaZones" field lists who controls what now); if two or more ops this turn claim the SAME zone for DIFFERENT nations, the zone is CONTESTED and the higher current "military" wins (a tie goes to the earlier-listed op). Every committed turn each zone's controller earns a small deterministic +1 military and +1 economy. Sea control NEVER moves land (no territory changes) — it is a parallel track. Propose at most 1-2 claims per turn and narrate each one in "events" (a "military" or "diplomatic" event).
+- Contested regions ("contested") are WAR FRONTLINES: a region that no nation controls and that is not no man's land, contested by two or more nations at war. An "open" op ({"regionKey":"<key>","parties":["<a>","<b>"]}) makes a region a frontline — it leaves its owner's territory (or no-man's-land) and is contested: the region's sole owner must be at war with at least one of the parties, or (for a no-man's-land region) two of the parties must be at war with each other. A "resolve" op (["<key>"]) ends a frontline, releasing the region to no man's land — unless a party's concurrent claim re-owns it. A contested region is in NO nation's territory (never two) and is never no man's land while contested. The user message's "contested" field lists the current frontlines (region key + party names). Propose at most 1-2 contested-region changes per turn and narrate each one in "events" (a "military" 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.

server/abilities/goldens/system-tool.txt

@@ -42,6 +42,7 @@ You have a getNeighbours tool: given region keys it returns the region keys that
   "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>"}]},
   "migration": {"ops":[{"kind":"<migration|refugees|diaspora|exodus>","from":"<nation id or name>","to":"<nation id or name>","scale":"<small|moderate|large>","detail":"<short detail>"}]},
   "sea": {"control":[{"zone":"<seaZoneId>","by":"<nation id or name>"}]},
+  "contested": {"open":[{"regionKey":"<region key>","parties":["<nation 1>","<nation 2>"]}],"resolve":["<region key>"]},
   "markers": {"add":[{"type":"<city|factory|army|port|capital|fleet|rocket|gathering>","name":"<short name>","regionKey":"<region key>"}],"remove":["<marker id>"]}
 }
 
@@ -70,6 +71,7 @@ HARD CONSTRAINTS
 - 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).
 - Migration & refugees ("migration.ops") are people moving between nations this turn: a "kind" ("migration", "refugees", "diaspora", or "exodus"), a "from" (the source nation — id or name), a "to" (the destination nation — required for every kind except "exodus", which has no destination), and a "scale" (small / moderate / large). The engine applies a DETERMINISTIC effect (no hidden randomness): the source LOSES a small amount of population and economy, the destination GAINS a small amount of population and economy (a "large" influx additionally strains the destination's stability by 2), and the from↔to relation moves one step toward the positive end of the ally/neutral/rival/hostile ladder — capped at "ally" for "refugees" (hosting refugees builds the strongest goodwill), capped at "neutral" for "migration"/"diaspora" (milder ties), and not at all for "exodus"; the nudge never creates or escalates a "war" (a warring pair is left untouched). The layer is turn-transient (no memory): a continuing flow is simply RE-DECLARED each turn it persists. It never moves borders — sole ownership is untouched. Propose at most 1-2 per turn and narrate each one in "events" (a "social" or "diplomatic" event).
 - Sea control ("sea") is the naval layer, fully parallel to but INDEPENDENT of land: each of the 12 fixed sea zones — "north-atlantic" (North Atlantic), "south-atlantic" (South Atlantic), "pacific" (Pacific Ocean), "indian" (Indian Ocean), "mediterranean" (Mediterranean Sea), "north-sea" (North Sea), "baltic" (Baltic Sea), "arctic" (Arctic Ocean), "black-sea" (Black Sea), "gulf-mexico" (Gulf of Mexico), "red-sea" (Red Sea), "sargasso" (Sargasso Sea) — is under the SOLE control of at most one nation. A control op ({"zone":"<id>","by":"<nation>"}) sets or replaces that zone's controller (the user message's "seaZones" field lists who controls what now); if two or more ops this turn claim the SAME zone for DIFFERENT nations, the zone is CONTESTED and the higher current "military" wins (a tie goes to the earlier-listed op). Every committed turn each zone's controller earns a small deterministic +1 military and +1 economy. Sea control NEVER moves land (no territory changes) — it is a parallel track. Propose at most 1-2 claims per turn and narrate each one in "events" (a "military" or "diplomatic" event).
+- Contested regions ("contested") are WAR FRONTLINES: a region that no nation controls and that is not no man's land, contested by two or more nations at war. An "open" op ({"regionKey":"<key>","parties":["<a>","<b>"]}) makes a region a frontline — it leaves its owner's territory (or no-man's-land) and is contested: the region's sole owner must be at war with at least one of the parties, or (for a no-man's-land region) two of the parties must be at war with each other. A "resolve" op (["<key>"]) ends a frontline, releasing the region to no man's land — unless a party's concurrent claim re-owns it. A contested region is in NO nation's territory (never two) and is never no man's land while contested. The user message's "contested" field lists the current frontlines (region key + party names). Propose at most 1-2 contested-region changes per turn and narrate each one in "events" (a "military" 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.

server/abilities/goldens/user.txt

@@ -206,5 +206,14 @@
       "type": "industry"
     }
   ],
-  "seaZones": []
+  "seaZones": [],
+  "contested": [
+    {
+      "regionKey": "b-r1",
+      "parties": [
+        "Alpha",
+        "Bravo"
+      ]
+    }
+  ]
 }

server/abilities/index.ts

@@ -1,8 +1,8 @@
 // The ordered LLM-ability registry.
 //
-// `ABILITIES` is the single source of truth for the 11 per-feature LLM abilities.
+// `ABILITIES` is the single source of truth for the 12 per-feature LLM abilities.
 // The engine iterates it in this order:
-//   takeovers → wars → hybrid → economy → industry → nuclear → leaders → ideology → disasters → migration → sea
+//   takeovers → wars → hybrid → economy → industry → nuclear → leaders → ideology → disasters → migration → sea → contested
 // 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,
@@ -25,10 +25,11 @@ import { ideology } from './ideology';
 import { disasters } from './disasters';
 import { migration } from './migration';
 import { sea } from './sea';
+import { contested } from './contested';
 import type { Ability, AbilityField } from './types';
 
 /**
- * The 11 per-feature LLM abilities in their canonical apply order.
+ * The 12 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. New
@@ -47,6 +48,7 @@ export const ABILITIES: readonly Ability<AbilityField>[] = [
   disasters,
   migration,
   sea,
+  contested,
 ];
 
 // ── type re-exports ────────────────────────────────────────────────────────────
@@ -173,3 +175,13 @@ export {
   isSeaZoneId,
   seaZoneName,
 } from './sea';
+
+// ── contested (frontlines) ───────────────────────────────────────────────────
+
+export {
+  validateContestedOps,
+  applyContested,
+  CONTESTED_FILL,
+  CONTESTED_STROKE,
+  contestedTooltipLabel,
+} from './contested';

server/abilities/migration.test.ts

@@ -84,6 +84,8 @@ function mkState(
     industry: [],
     // (v0.43.0, #65) no sea-zone control on a fresh state.
     seaZones: [],
+    // (v0.44.0, #66) no contested regions on a fresh state.
+    contested: [],
   };
 }
 

server/abilities/registry.test.ts

@@ -12,7 +12,7 @@
 //      by the disasters feature (its payload is always empty).
 //
 //   2. REGISTRY CONTRACT — the ABILITIES registry is the canonical ordered
-//      list of the 11 abilities; each ability's default() equals the canonical
+//      list of the 12 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
@@ -76,6 +76,12 @@ import {
   SEA_ZONE_IDS,
   isSeaZoneId,
   seaZoneName,
+  // contested (v0.44.0, #66)
+  validateContestedOps,
+  applyContested,
+  CONTESTED_FILL,
+  CONTESTED_STROKE,
+  contestedTooltipLabel,
 } from '../engine';
 import { createPresetStore } from '../presets';
 import { ABILITIES } from './index';
@@ -92,7 +98,7 @@ import type {
   SeaZoneClaim,
   TradeAgreement,
 } from '../../shared/types';
-import type { MarkerInfo, TurnResult, WarInfo } from '../../shared/protocol';
+import type { ContestedRegion, MarkerInfo, TurnResult, WarInfo } from '../../shared/protocol';
 
 const here = path.dirname(fileURLToPath(import.meta.url));
 const goldensDir = path.join(here, 'goldens');
@@ -165,6 +171,8 @@ const state: GameState = {
   industry: [],
   // (v0.43.0, #65) no sea-zone control on a fresh state.
   seaZones: [],
+  // (v0.44.0, #66) no contested regions on a fresh state.
+  contested: [],
 };
 
 // --- buildUserPrompt arguments: every optional branch exercised. ---
@@ -202,6 +210,10 @@ const nationResources: Record<string, RegionResources> = {
 const industryProjects: IndustryProject[] = [{ regionKey: 'a-r1', type: 'industry' }];
 const nuclear: Record<string, boolean> = { a1: true, b2: false, c3: false };
 const seaZones: SeaZoneClaim[] = [];
+// (v0.44.0, #66) a non-empty contested sample so the golden's user payload
+// includes the `contested` key (region key + party NAMES, resolved from the
+// state's nations). `b-r1` is owned by b2; the parties are a1 + b2.
+const contested: ContestedRegion[] = [{ regionKey: 'b-r1', parties: ['a1', 'b2'] }];
 
 /**
  * Assert the current prompt output is byte-identical to the committed golden —
@@ -241,6 +253,7 @@ function fullDefaultTurn(): TurnResult {
     disasters: { events: [] },
     migration: { ops: [] },
     sea: { control: [] },
+    contested: { open: [], resolve: [] },
     markers: { add: [], remove: [] },
   };
 }
@@ -270,11 +283,13 @@ function meaningfulFor(field: AbilityField): TurnResult[AbilityField] {
       return { ops: [{ kind: 'migration', from: 'a1', to: 'b2', scale: 'small' }] };
     case 'sea':
       return { control: [{ zone: 'pacific', by: 'a1' }] };
+    case 'contested':
+      return { open: [{ regionKey: 'b-r1', parties: ['a1', 'b2'] }], resolve: [] };
   }
 }
 
 describe('ABILITIES registry (v0.40.0, #67)', () => {
-  it('is the canonical 11-ability order (takeovers → sea)', () => {
+  it('is the canonical 12-ability order (takeovers → contested)', () => {
     expect(ABILITIES.map((a) => a.field)).toEqual([
       'takeovers',
       'wars',
@@ -287,13 +302,14 @@ describe('ABILITIES registry (v0.40.0, #67)', () => {
       'disasters',
       'migration',
       'sea',
+      'contested',
     ]);
   });
 
-  it('lists 11 distinct fields, each a key of TurnResult', () => {
+  it('lists 12 distinct fields, each a key of TurnResult', () => {
     const fields = ABILITIES.map((a) => a.field);
-    expect(fields).toHaveLength(11);
-    expect(new Set(fields).size).toBe(11);
+    expect(fields).toHaveLength(12);
+    expect(new Set(fields).size).toBe(12);
     const all = fullDefaultTurn();
     for (const f of fields) expect(f in all).toBe(true);
   });
@@ -324,6 +340,7 @@ describe('ABILITIES registry (v0.40.0, #67)', () => {
         industryProjects,
         nuclear,
         seaZones,
+        contested,
       ),
     );
   });
@@ -353,13 +370,13 @@ describe('ABILITIES registry (v0.40.0, #67)', () => {
   it('declares exactly the durable GameState fields the db migration must default', () => {
     const owned: string[] = [];
     for (const a of ABILITIES) if (a.stateFields) owned.push(...a.stateFields);
-    expect([...owned].sort()).toEqual(['embargoes', 'industry', 'seaZones', 'trades', 'wars']);
+    expect([...owned].sort()).toEqual(['contested', 'embargoes', 'industry', 'seaZones', 'trades', 'wars']);
   });
 
   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 an 11th ability is appended.
+    // constraint bullet — must keep working when a 12th ability is appended.
     // This documents the extension point without widening the closed
     // AbilityField union.
     interface Loopable {
@@ -378,9 +395,9 @@ 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(12);
-    expect(extended.map((a) => a.constraint())).toHaveLength(12);
-    expect(extended[11].schemaLine()).toBe('  "custom": [],');
+    expect(extended.map((a) => a.schemaLine())).toHaveLength(13);
+    expect(extended.map((a) => a.constraint())).toHaveLength(13);
+    expect(extended[12].schemaLine()).toBe('  "custom": [],');
   });
 
   it('the engine still re-exports every name its callers import from it', () => {
@@ -439,6 +456,12 @@ describe('ABILITIES registry (v0.40.0, #67)', () => {
       SEA_ZONE_IDS,
       isSeaZoneId,
       seaZoneName,
+      // contested (v0.44.0, #66)
+      validateContestedOps,
+      applyContested,
+      CONTESTED_FILL,
+      CONTESTED_STROKE,
+      contestedTooltipLabel,
     };
     for (const [name, value] of Object.entries(reexported)) {
       expect(value, `engine should re-export ${name}`).toBeDefined();

server/abilities/sea.test.ts

@@ -85,6 +85,8 @@ function mkState(
     embargoes: [],
     industry: [],
     seaZones,
+    // (v0.44.0, #66) no contested regions on a fresh state.
+    contested: [],
   };
 }
 

server/abilities/types.ts

@@ -15,14 +15,14 @@ import type {
   SeaZoneClaim,
   TradeAgreement,
 } from '../../shared/types';
-import type { MarkerInfo, TurnResult, WarInfo } from '../../shared/protocol';
+import type { ContestedRegion, MarkerInfo, TurnResult, WarInfo } from '../../shared/protocol';
 
 /**
- * The 11 per-feature LLM abilities a turn can exercise, by the `TurnResult`
+ * The 12 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 eleven abilities.
+ * / markers) plus, in order, these twelve abilities.
  */
 export type AbilityField =
   | 'takeovers'
@@ -35,7 +35,8 @@ export type AbilityField =
   | 'ideology'
   | 'disasters'
   | 'migration'
-  | 'sea';
+  | 'sea'
+  | 'contested';
 
 /**
  * Everything a single ability's `apply` may need from the surrounding turn.
@@ -92,6 +93,7 @@ export interface UserPromptCtx {
   readonly nationResources?: Record<string, RegionResources>;
   readonly industryProjects?: IndustryProject[];
   readonly seaZones?: SeaZoneClaim[];
+  readonly contested?: ContestedRegion[];
 }
 
 /**