feat(#60): nuclear/WMD — capability flag + strikes (region → no-man's-land, nation collapse + war capitulation, MAD retaliation) (v0.37.0)

CHANGELOG.md

@@ -2,6 +2,23 @@
 
 All notable changes to **History** are listed here, newest first.
 
+## v0.37.0 — 2026-10-15 19:15
+- **#60: Nuclear / WMD — a per-nation `nuclear` capability flag + a `TurnResult.nuclear` lever (`arm` + `strikes`) with deterministic strikes and MAD retaliation.** A nation is *nuclear-capable* when its `nuclear` flag is `true` **or** it currently owns a `rocket` marker (a launch site is an arsenal). The model can **arm** nations (grant the flag — idempotent; a newly-armed nation is capable the same turn, since `arm` is applied before `strikes`) and fire **strikes** (`{ from, target }`). The engine is **fully deterministic (no hidden randomness)** and **additive** (a `db.ts` change is not needed — `nuclear` is an optional `Nation` field; a pre-v0.37 row loads with the flag absent).
+  - **Capability (`shared/protocol.ts`).** `isNuclearCapable(nation, markers)` — exported pure helper: `nation.nuclear === true` **or** it owns a `rocket` marker (`marker.type === 'rocket' && marker.ownerNationId === nation.id`). Markers supply the *pre-turn* rocket set, so a rocket placed this turn makes the owner capable from the *next* turn.
+  - **Types (`shared/types.ts`).** `Nation.nuclear?: boolean` (optional; `undefined`/absent = not armed; default `false` behavior).
+  - **Protocol (`shared/protocol.ts`).** New `NuclearStrike` (`{ from; target }` — `from` is the striking nation, `target` is a nation ref or a region key) and `NuclearOps` (`{ arm: string[]; strikes: NuclearStrike[] }`); `TurnResult.nuclear` is **required**, placed between `industry` and `markers`, default `{ arm: [], strikes: [] }`. New exported `NuclearStatKey` (`'economy' | 'military' | 'stability'`) and the two deterministic collapse tables: **`NUCLEAR_COLLAPSE = { economy: −40, military: −50, stability: −40 }**` (a full strike's effect on the struck nation / region owner) and **`NUCLEAR_RETALIATION = { economy: −20, military: −25, stability: −20 }`**` (the half-strength MAD backfire).
+  - **Engine (`server/engine.ts`).**
+    - `validateNuclearOps(raw)` — new exported, defensive validator (never throws): a missing/malformed object yields `{ arm: [], strikes: [] }`; `arm` entries are non-empty strings (≤120 chars) deduped; a strike needs a non-empty `from` **and** `target` (≤120) and is **dropped when it targets itself** (same ref, case-insensitive) — a self-strike is a no-op, never thrown.
+    - `applyNuclearOps(next, ops, state, geoOf?, validKeys?, regionNameOf?, actingTurn?)` — new exported, the load-bearing nuclear block. **`arm` first** (idempotent; a resolve miss or a self-arm is a no-op), then **`strikes`** in order: resolve `from` (an unresolvable or non-capable striker is **dropped** — capability checked against the *pre-turn* marker set plus any flag granted this turn); a `target` that is a **nation** collapses it (the `NUCLEAR_COLLAPSE` deltas applied to its `stats` and every region it owns, each affected nation's derived stats re-derived, 0-region / no-entry guards as elsewhere), ends **every active war it fights** by **capitulation** (`endWarsBetween` captures the active pairs *before* ending so a war declared+ended the same turn is handled), and downgrades the now-inactive `war` relations to `hostile`; a `target` that is a **region key** releases it to no man's land (a key with 0 or 2+ owners, or one the striker itself owns, is **dropped**), deletes its `regionStats` entry, and collapses its **sole owner** the same way. **MAD**: if the struck nation (or the struck region's sole owner) is itself nuclear-capable, it retaliates against the striker for the half-strength `NUCLEAR_RETALIATION` (clamped, mirrored, re-derived) and the two nations' relations are forced to `hostile` (`forceHostile` — both directions, unless already `war`). Each strike and each retaliation appends a dramatic **`military`** event (`war` is not a valid `EventType`). Sole ownership is never broken by a strike (a region is released, not re-claimed) and the block never throws.
+    - `applyTurnResult` — the nuclear block runs **after `industry` and before `markers`** (order: events → relations → territory → stateChanges → recompute → wars → hybrid → economy → industry → **nuclear** → markers → nationOps); it passes the *original* (pre-turn) `state` for the capability marker set and the current `regionNameOf` for event text.
+    - `isMeaningful` — a non-empty `nuclear.arm` or `nuclear.strikes` makes a turn meaningful.
+    - `validateTurnResult` — initializes and validates `nuclear` (default `{ arm: [], strikes: [] }`).
+    - `buildSystemPrompt` — documents the `nuclear` field and a constraint bullet (the capability rule; `arm` is idempotent; a strike hits a nation or a region; the collapse + capitulation + MAD outcomes; at most one strike per turn, always narrated) in both tool and plain modes.
+    - `buildUserPrompt` — new optional `nuclear` param (`Record<string, boolean>`, the per-nation capability map); when provided, each `state.nations` entry in the payload is stamped with its `nuclear` capability; when undefined the key is omitted entirely (stub / no-capability prompt stays byte-identical). `runTurn` always supplies the map (computed from `isNuclearCapable` over `state.markers`).
+  - **Stub (`server/stub.ts`).** `deterministicTurn` always returns `nuclear: { arm: [], strikes: [] }` — the stub **never** arms a nation or fires a strike, so the e2e (CI, `LLM_STUB=1`) is unaffected and the nuclear path is covered by unit tests only.
+  - **Tests.** 29 new unit tests: `isNuclearCapable` (flag / own rocket / non-rocket / other's rocket / null owner); `validateNuclearOps` (well-formed, `arm` dedupe, missing `from`/`target`, self-target drop, malformed top-level); `applyTurnResult` nuclear (arm idempotency across turns, arm+strike same turn, region strike → release + stats deleted + owner collapse + no MAD + the single `military` event, nation strike + pre-existing war → capitulation + hostile, nation strike + same-turn declare → capitulation + hostile, MAD on a capable nation target, MAD on a capable region owner, rocket-marker-only capability, non-capable striker dropped, 2+-owner region dropped, 0-owner/unowned region dropped, self-target dropped, malformed strikes never throw); `isMeaningful` (arm / strike); `buildUserPrompt` (per-nation capability stamped when the map is given, omitted when undefined); and two `db.test.ts` round-trips (a legacy row with no flag loads with it absent; a set flag round-trips through save/load).
+- **Version** bumped `0.36.0 → 0.37.0`.
+
 ## v0.36.0 — 2026-10-15 18:17
 - **#59: Resources & Industry — per-region synthesized resource profiles + a per-region industry-project lever with a deterministic per-turn economy boost.** Every prior lever moved borders, dipped stats one-shot, or proposed a player-confirmed change; this version adds a **resource abundance layer** (every sub-region gets a synthesized 4-value profile) and a **development lever**: the model can build industry projects (oil facilities, iron mines, food operations, factories) in individual regions, and every committed turn each active project pays its region's sole owner a small, deterministic economy gain scaled by the region's `industry` resource value. The engine is **fully deterministic (no hidden randomness)**: the resource profiles are a pure function of the region key (FNV-1a) scaled by an area factor, and the per-turn effect is a fixed, clamped, mirrored, re-derived stat adjustment.
   - **Manifest (`public/region-resources.json`, new).** 1,800 entries — region key → `{ oil, iron, food, industry }` (each 0–1, 2dp) — built by the new turf-free, deterministic, **idempotent** `scripts/build-region-resources.mjs` (`npm run build:region-resources`): per resource, `(fnv1a32(`${key}\u0000${resource}`) & 0x3fff) / 0x4000` → [0,1), times an area factor `1 + 0.2·min(1, log10(1+area)/8)` (max ≈1.2) from `region-geo.json` (missing geo / zero area → pure hash), clamped to 1, keys sorted, byte-identical re-run. Pinned by `scripts/build-region-resources.test.ts` (key-set equality vs `region-keys.json`, sorted order, per-entry shape, spot-checked values, determinism via a re-run).