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+# Day Counter + 2x Indicator Design
+
+## Goal
+
+Add a day counter ("Day N") to the left of the day/night indicator, and double the indicator's size.
+
+## Approach
+
+Server computes `dayNumber` in GameLoop, sends it in StateUpdate. Client displays it. Existing inline day calculation in inventionSystem is replaced with the centralized method.
+
+## Server Changes
+
+- **GameLoop**: Add `getCycleTicks()` helper (extracted from `getGameTime()`), add `getDayNumber()` method
+- **StateUpdate type** (`shared/src/types.ts`): Add `dayNumber: number`
+- **SocketServer**: Include `dayNumber` in state broadcast
+- **inventionSystem.ts**: Use `gameLoop.getDayNumber()` instead of inline cycle math
+
+## Client Changes
+
+- **TimeIndicator**: Double all dimensions (track 240px, height 16px, icons 20/18px, marker 6px, border 4px)
+- **TimeIndicator**: Add "Day N" text element to the left of the track, same retro font
+- **TimeIndicator.update()**: Accept `dayNumber` parameter, update text when it changes
+- **GameScene**: Pass `dayNumber` from state updates to TimeIndicator
+
+## Data Flow
+
+```
+GameLoop.tick → getDayNumber() → StateUpdate.dayNumber → TimeIndicator.update(gameTime, dayNumber)
+```