GeoPolity Diplomacy Depth (SP2-inspired)

name: GeoPolity Diplomacy Depth overview: Deepen Novolis.Geopolitics with SP2-inspired multilateral treaties, trade blocs (common market / economic partnership), resource flows, and first-class supranationals—homage mechanics only, no SDK/GDB vendoring. todos:

• id: multilateral-treaties

content: Rewrite Treaty as multilateral (+ directed SideA/B); expand TreatyKind; migrate Diplomacy/WorldState helpers status: completed

• id: resources-trade

content: Add ResourceKind ledgers, province weights, monthly TradeResolver (CM → world market → embargo) status: completed

• id: supranationals

content: Add Supranational + continent seed orgs with charter-linked Alliance/CM/Research treaties status: completed

• id: treaty-effects-ai

content: Wire EP/CM/aid/research/access effects into month tick; AI create/join/leave/embargo status: completed

• id: seed-regen-ui-tests

content: Regen world-seed.json; extend GeoPolity UI/report; unit tests + 50y smoke; diplomacy-homage.md status: completed isProject: false

Inspiration (disk, not shipped)

Read-only reference from local Steam SDK (`D:\Steam\steamapps\common\SuperPower 2\Extras\SDK\SDK1.5.7.zip`):

• GTreaty is multilateral (Side A / Side B / pressure, name, creator, suspend) — `sp2_treaty.h`
• ETreatyType: Alliance, MilitaryAccess, EconomicPartnership, CommonMarket, EconomicAid, EconomicEmbargo, WeaponTrade(+Embargo), ResearchPartnership, CulturalExchanges, Annexation, … — `sp2_constants.h`
• AI joins/creates by type with soft caps (CreateOrJoinTreaty, e.g. ≤3 CommonMarkets) — `sp2_common_market.cpp`

IP lock: homage formulas only; never commit SDK extracts, GDB, or SP2 string tables. Keep `docs/seed-attribution.md` + README homage notice. Ensure artifacts/sp2-sdk-peek stays gitignored / deleted after use.

Supreme Ruler–style dept micromanagement stays out of scope; we take SP2’s political/economic treaty + resource-sharing pillars.

Gap today

`Treaty` is bilateral A/B with thin Peace|Alliance|Trade. Trade has no economic effect. No resources, no multilateral blocs, no named orgs.

Locked design

flowchart TB
  subgraph core [Core model]
    Res[ResourceLedger]
    Tr[Treaty multilateral]
    Org[Supranational]
    WS[WorldState]
  end
  subgraph sim [Simulation month]
    Trade[TradeResolver]
    Effects[TreatyEffects]
    AI[PolityAi join/create]
  end
  WS --> Tr
  WS --> Org
  WS --> Res
  Tr --> Effects
  Org --> Effects
  Res --> Trade
  Effects --> Res
  AI --> Tr
  AI --> Org

1. Multilateral treaties (replace bilateral-only)

Evolve Treaty to SP2-shaped (original C#):

• Id, Name, Kind, Creator, SignedDay, ExpiresDay, Active
• Members (HashSet<PolityId>) for single-side instruments (Alliance, CommonMarket, EconomicPartnership, ResearchPartnership, MilitaryAccess)
• SideA / SideB for directed instruments (EconomicEmbargo, EconomicAid, WeaponTradeEmbargo)
• Drop the old 2-field A/B shape; migrate helpers on WorldState / Diplomacy

Kinds in this slice (subset of SP2, enough for depth):

Legacy TreatyKind.Trade maps to EconomicPartnership (or delete and regenerate seed consumers).

2. Supranationals

New first-class Supranational:

• Id, Name, ContinentHint (optional), MemberIds, Charter flags: HasCommonMarket, HasAlliance, HasResearchPact
• At seed time, create one org per continent (8) with the continent’s top ~6 polities by GDP; wire charter → linked multilateral treaties (same member set)
• Orgs are joinable/leavable; leaving breaks linked treaty membership and costs relation (−10 homage to SP2 leave penalty)
• Voting weight = GDP share (used later; MVP: AI join if relation to median member ≥ threshold)

This is the “supra-national” layer the user asked for — not a full UN sim, but persistent named blocs with economic + military charters.

3. Resources (enables real trade alliances)

Add compact resource model (not full Novolis.Economy):

• ResourceKind: Food, Energy, Materials, Goods, MilitaryGoods, Rare (6)
• Per polity monthly: Production[k], Consumption[k] derived from owned provinces (population/wealth/coastal/tech) + military upkeep → MilitaryGoods
• TradeResolver monthly order:

1. Domestic balance
2. CommonMarket internal clear (members first)
3. World market among non-embargoed pairs (GDP-weighted sellers)
4. Shortages → stability / GDP drag; surpluses → treasury crumbs

Province seed: add per-province resource weights (procedural); regenerate world-seed.json via SeedGen.

4. Simulation / AI

• Month pipeline: budget → resources + treaty effects → AI
• AI (inspired by SP2 EHE caps): create/join Alliance / CommonMarket / EconomicPartnership / ResearchPartnership; prefer continent neighbors; soft global caps (~3 AI-created CM/Alliance waves); embargo rivals when relation < −40 and at war or bordering
• Alliance defense: keep/extend defender-ally join

5. Bridge + tests

`apps/GeoPolity/Program.cs`:

• Rows: active orgs, CM membership counts, global resource shortage index, embargo count
• Headless report: orgs, CM clears, embargoes, EP GDP boost aggregate

Tests: multilateral join; CM fills deficit; embargo blocks pair; EP raises GDP vs control; org leave drops membership; 50y smoke still exits 0.

6. Docs

• `docs/diplomacy-homage.md`: maps our kinds → SP2 pillars (homage, not parity); no code quotes from SDK
• Update README feature list

Out of scope (this pass)

Unit designs / TO&E, nukes, espionage, annexation treaties, full government types, Novolis.Economy bridge, Raylib/Avalonia globe.

Verification

dotnet test d:\novolis\novolis-geopolitics\tests\Novolis.Geopolitics.Unit\Novolis.Geopolitics.Unit.csproj
dotnet run --project d:\novolis\novolis-geopolitics\apps\GeoPolity -- --headless --years 50