fix: clear thumbnail cache and temp dirs on new session

Co-authored-by: Cursor <cursoragent@cursor.com>

src-tauri/src/commands/media_analysis.rs

@@ -35,3 +35,10 @@ pub async fn extract_thumbnails(
     .await
     .map_err(|e| format!("Task failed: {e}"))?
 }
+
+#[tauri::command]
+pub async fn cleanup_thumbnails(paths: Vec<String>) -> Result<(), String> {
+    tokio::task::spawn_blocking(move || thumbnail_extractor::cleanup_thumbnail_dirs(&paths))
+        .await
+        .map_err(|e| format!("Task failed: {e}"))?
+}

src-tauri/src/lib.rs

@@ -19,6 +19,7 @@ pub fn run() {
             media_analysis::extract_keyframes,
             media_analysis::extract_waveform,
             media_analysis::extract_thumbnails,
+            media_analysis::cleanup_thumbnails,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");

src-tauri/src/services/thumbnail_extractor.rs

@@ -76,6 +76,17 @@ pub fn extract_thumbnails(
     Ok(sheets)
 }
 
+pub fn cleanup_thumbnail_dirs(paths: &[String]) -> Result<(), String> {
+    for path in paths {
+        let dir = std::path::Path::new(path);
+        if dir.is_dir() {
+            std::fs::remove_dir_all(dir)
+                .map_err(|e| format!("Failed to remove thumbnail dir {path}: {e}"))?;
+        }
+    }
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/lib/bindings/mediaAnalysis.ts

@@ -30,3 +30,7 @@ export async function extractThumbnails(
     duration,
   });
 }
+
+export async function cleanupThumbnails(paths: string[]): Promise<void> {
+  return invoke<void>('cleanup_thumbnails', { paths });
+}

src/lib/stores/videoSession.svelte.ts

@@ -2,10 +2,12 @@ import type { VideoMetadata } from '$lib/bindings/video';
 import { startDownload } from '$lib/bindings/video';
 import type { ThumbnailSpritesheet } from '$lib/bindings/mediaAnalysis';
 import {
+  cleanupThumbnails,
   extractKeyframes,
   extractThumbnails,
   extractWaveform,
 } from '$lib/bindings/mediaAnalysis';
+import { clearThumbnailCache } from '$lib/timeline/thumbnailRenderer';
 
 export type SessionStatus = 'idle' | 'resolving' | 'ready' | 'error';
 export type DownloadStatus = 'idle' | 'downloading' | 'complete' | 'failed';
@@ -112,6 +114,10 @@ async function triggerPostDownloadProcessing(filePath: string) {
 export async function beginDownload() {
   if (!session.url) return;
 
+  const oldThumbnailDirs = [
+    ...new Set(session.thumbnailSpritesheets.map((sheet) => sheet.filePath)),
+  ];
+  clearThumbnailCache();
   session.downloadStatus = 'downloading';
   session.downloadProgress = 0;
   session.localFilePath = null;
@@ -119,6 +125,12 @@ export async function beginDownload() {
   session.waveformPeaks = [];
   session.thumbnailSpritesheets = [];
 
+  if (oldThumbnailDirs.length > 0) {
+    void cleanupThumbnails(oldThumbnailDirs).catch((err) => {
+      console.error('Thumbnail temp dir cleanup failed:', err);
+    });
+  }
+
   try {
     await startDownload(
       session.url,

src/lib/timeline/thumbnailRenderer.ts

@@ -4,6 +4,10 @@ import { timeToX, type TimelineState } from './renderer';
 
 const imageCache = new Map<string, HTMLImageElement>();
 
+export function clearThumbnailCache(): void {
+  imageCache.clear();
+}
+
 const TARGET_SPACING_PX = 100;
 
 function getImagePath(dir: string, frameIndex: number): string {