feat: Refine session clear to preserve UI preferences while resetting game state and standardize image cache paths to full and crop subdirectories.

docs/development/devlog/2025-12-18-213900_implicit_image_caching.md

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+# 2025-12-18 - Implicit Image Caching
+
+## Overview
+To solve the issue of missing images when generating packs from local servers, we have implemented implicit image caching directly within the API routes.
+
+## Changes
+- **Updated `server/index.ts`**:
+  - `GET /api/sets/:code/cards`: Now calls `cardService.cacheImages(cards)` before returning the response. This ensures that when a user fetches a set, all necessary full art and art crop images are downloaded to the server's cache immediately.
+  - `POST /api/cards/parse`: Now calls `cardService.cacheImages(uniqueCards)` on the resolved unique cards before building the expanded list.
+
+## Impact
+- **Positive**: Guaranteed image availability. When the client receives the card list, the images are guaranteed to optionally exist or be in the process of finishing (though we await completion, ensuring existence).
+- **Performance**: The "Fetching set..." or "Parsing list..." steps in the UI will take longer initially (proportional to image download speed), but subsequent requests will be instant as `cacheImages` skips existing files.
+- **Reliability**: Eliminates 404 errors for images when using the strictly local `PackGenerator` URLs.
+
+## Rationale
+The application now defaults to `useLocalImages = true` effectively by hardcoding local paths in the generator. Therefore, the server MUST ensure those files exist before the client tries to render them.