diff --git a/server/src/industry/__tests__/inventionTimeline.test.ts b/server/src/industry/__tests__/inventionTimeline.test.ts
new file mode 100644
index 0000000..7d66892
--- /dev/null
+++ b/server/src/industry/__tests__/inventionTimeline.test.ts
@@ -0,0 +1,44 @@
+import { describe, it, expect } from 'vitest';
+import { createInventionTimeline, type InventionTimeline } from '../inventionTimeline.js';
+
+describe('InventionTimeline', () => {
+  it('starts empty', () => {
+    const timeline = createInventionTimeline();
+    expect(timeline.getAll()).toEqual([]);
+  });
+
+  it('records an invention entry', () => {
+    const timeline = createInventionTimeline();
+    timeline.record({
+      itemId: 'rope',
+      inventorEntityId: 1,
+      inventorName: 'Gwen',
+      tick: 500,
+      day: 2,
+    });
+    const all = timeline.getAll();
+    expect(all).toHaveLength(1);
+    expect(all[0].itemId).toBe('rope');
+    expect(all[0].inventorName).toBe('Gwen');
+  });
+
+  it('counts inventions per entity', () => {
+    const timeline = createInventionTimeline();
+    timeline.record({ itemId: 'rope', inventorEntityId: 1, inventorName: 'Gwen', tick: 500, day: 2 });
+    timeline.record({ itemId: 'clay', inventorEntityId: 1, inventorName: 'Gwen', tick: 600, day: 2 });
+    timeline.record({ itemId: 'kiln', inventorEntityId: 2, inventorName: 'Bram', tick: 700, day: 3 });
+
+    expect(timeline.countByEntity(1)).toBe(2);
+    expect(timeline.countByEntity(2)).toBe(1);
+    expect(timeline.countByEntity(3)).toBe(0);
+  });
+
+  it('returns entries in insertion order', () => {
+    const timeline = createInventionTimeline();
+    timeline.record({ itemId: 'a', inventorEntityId: 1, inventorName: 'X', tick: 300, day: 1 });
+    timeline.record({ itemId: 'b', inventorEntityId: 2, inventorName: 'Y', tick: 100, day: 1 });
+    const all = timeline.getAll();
+    expect(all[0].tick).toBe(300);
+    expect(all[1].tick).toBe(100);
+  });
+});
diff --git a/server/src/industry/inventionTimeline.ts b/server/src/industry/inventionTimeline.ts
new file mode 100644
index 0000000..ef4d57e
--- /dev/null
+++ b/server/src/industry/inventionTimeline.ts
@@ -0,0 +1,33 @@
+import type { EntityId } from '@dflike/shared';
+
+export interface InventionEntry {
+  itemId: string;
+  inventorEntityId: EntityId;
+  inventorName: string;
+  tick: number;
+  day: number;
+}
+
+export interface InventionTimeline {
+  record(entry: InventionEntry): void;
+  getAll(): InventionEntry[];
+  countByEntity(entityId: EntityId): number;
+}
+
+export function createInventionTimeline(): InventionTimeline {
+  const entries: InventionEntry[] = [];
+
+  return {
+    record(entry: InventionEntry): void {
+      entries.push(entry);
+    },
+
+    getAll(): InventionEntry[] {
+      return [...entries];
+    },
+
+    countByEntity(entityId: EntityId): number {
+      return entries.filter(e => e.inventorEntityId === entityId).length;
+    },
+  };
+}