diff --git a/src/packages/guide/src/types/simulation.ts b/src/packages/guide/src/types/simulation.ts
new file mode 100644
index 00000000..ce416ed0
--- /dev/null
+++ b/src/packages/guide/src/types/simulation.ts
@@ -0,0 +1,45 @@
+import type { TurnStats, EcologicalEvent, FramePayload, EventTriggeredResponse } from '@magic-civ/engine-ts'
+
+/** Per-scenario accumulated data from the simulation worker. */
+export interface ScenarioData {
+  stats: TurnStats[]
+  events: EcologicalEvent[][]
+  totalTurns: number
+  bufferReady: boolean
+  timings: number[]
+  loadDurationMs: number | null
+}
+
+/** Progress update from the simulation worker. */
+export interface SimProgress {
+  scenarioId: string
+  pct: number
+  phase: 'generating' | 'geology' | 'scenario' | 'buffering'
+  bufferedFrames?: number
+  totalBufferFrames?: number
+}
+
+export type { EventTriggeredResponse }
+
+/** Info about a manually triggered ecological event. */
+export interface TriggeredEventInfo {
+  category: string
+  tier: number
+  turn: number
+}
+
+/** Return type of useSimulationWorker — the full simulation control surface. */
+export interface UseSimulationWorkerResult {
+  scenarios: Map<string, ScenarioData>
+  currentFrame: FramePayload | null
+  referenceFrame: FramePayload | null
+  progress: SimProgress | null
+  isReady: boolean
+  lastTriggeredEvent: TriggeredEventInfo | null
+
+  runScenario: (scenarioId: string, turns: number, bufferFrames: number, seed?: number) => void
+  extendScenario: (scenarioId: string, turns: number) => void
+  requestFrame: (scenarioId: string, turn: number) => void
+  cancelScenario: (scenarioId: string) => void
+  triggerEvent: (scenarioId: string, category: string, tier: number) => void
+}