feat(diplomacy): Sprint 3.2 – Diplomatic Plays 4-Phase Escalation System

[Copilot]

The game had a basic treaty system but no escalation model. This implements the full Cooperation → Threat → Ultimatum → War pipeline with Trust/Threat as independent bilateral axes, per the design doc (GAMEPLAY_DATA_MODEL.md §6.4).

Data Layer

• sql/migrate_diplomatic_plays_v1.sql — adds trust_level, threat_level, trust_decay_rate to diplomacy table; creates diplomatic_plays table tracking phase, timestamps, demands, outcome, and trust/threat snapshots

Backend (api/diplomatic_plays.php)

Six actions: propose_play (opens Cooperation phase, +3 trust), counter_play (→ Threat, −5 trust, +10 threat), mobilize (→ Ultimatum, −10 trust, +10 threat), resolve (deal/war/withdrawal with standing + trust/threat deltas), trust_threat, list. AI acceptance probability factors in current trust, threat, faction aggression, and current phase:

function dp_ai_accept_pct(float $trust, float $threat, int $aggression, string $phase): int {
    $base = 50 + (int)($trust * 0.3);
    $base -= (int)($threat * 0.25);
    $base -= match($phase) { 'cooperation'=>0, 'threat'=>15, 'ultimatum'=>30, default=>50 };
    $base -= (int)(($aggression / 100) * 20);
    return max(5, min(95, (int)$base));
}

War resolution attempts to insert into a wars table if it exists (graceful no-op otherwise).

Frontend

• RuntimeDiplomaticPlaysDataModel.js — pure data model: phase/goal/outcome metadata, trustBarHTML() (−100..+100 normalised), threatBarHTML() (0..100), phaseStepperHTML() (done/active/pending steps), playCardHTML() (contextual action buttons per phase)
• RuntimeDiplomaticPlaysPanel.js — renders Trust/Threat bars, active/historical play cards, new-play form; handles all phase transitions with confirmation guards on destructive actions

Wiring

• api.js — 6 new methods (diplomaticPlaysList, diplomaticPlaysTrustThreat, diplomaticPlaysPropose, diplomaticPlaysCounter, diplomaticPlaysMobilize, diplomaticPlaysResolve)
• RuntimeFactionsController.js — adds 🎭 Plays tab button + plays mode handler alongside existing treaties mode
• RuntimeSocialControllersBootstrap.js + game.js — instantiate and wire both new runtime modules

Tests

38 unit tests in tests/js/diplomatic-plays.test.js covering phase ordering, index lookups, trust/threat bar clamping/coloring, phase stepper done/active/pending counts, play card action button variants, and panel render/interaction flows.