chore: release 1.8.1

First build from the redacted history, and the first that does not ship
source comments in the server bundle.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UXfdJu7QhSJLr47K7koTDF

.dockerignore

@@ -1,5 +1,6 @@
 node_modules
 dist
+dist-server
 .git
 .github
 _sample-archives

.gitignore

@@ -1,6 +1,7 @@
 node_modules/
 build/
 dist/
+dist-server/
 coverage/
 .DS_Store
 *.log
@@ -8,3 +9,5 @@ coverage/
 !.env.example
 _sample-archives
 _gemini-plans
+__pycache__/
+*.pyc

CLAUDE.md

@@ -0,0 +1,164 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+InstaArchive Viewer is a React 19 + Vite 6 PWA for browsing archived Instagram data (official Instagram exports and Instaloader archives). All archive *parsing* happens client-side in the browser; the Express backend only indexes and serves files from disk, and never parses archive contents.
+
+## Commands
+
+- `npm install` — install dependencies
+- `npm run dev` — Vite dev server on port 3000 (proxies `/api` and `/archives` to `http://localhost:3001`)
+- `npm run server` — Express backend (`tsx server.ts`) on port 3001, serving `ARCHIVES_DIR` (defaults to `./_sample-archives`)
+- `npm run build` — frontend to `dist/`, backend to `dist-server/`
+- `npm run lint` — type-check only (`tsc --noEmit`)
+- `npm test` / `npm run test:watch` — vitest
+- `npx vitest run src/lib/archive-patterns.test.ts` — a single test file
+
+Local development usually needs both `npm run dev` and `npm run server`. Local-folder mode works without the backend; server-mode archives do not.
+
+## Architecture
+
+### Two archive sources, one data model
+
+Loading is unified behind the `ArchiveFile` interface (`src/types/index.ts`, implementations in `src/lib/archive-files.ts`):
+
+- **`LocalArchiveFile`** — wraps a browser `File`. `createObjectUrl()` mints a **disk-backed** blob URL directly from the File; never route media through `arrayBuffer()`, which pulls whole files into memory.
+- **`RemoteArchiveFile`** — wraps a file served from `/archives/...`, fetched on demand.
+
+`revocable` tells callers whether the returned URL must be revoked. The scanner tracks every minted URL and releases them on archive teardown.
+
+### Sidecar directories
+
+An archive root holds one directory per profile plus *sidecars* that belong to it:
+
+```
+4utumn07                                 -> posts (base)
+4utumn07 - reels                         -> reels
+story - 4utumn07                         -> stories
+story highlights - 4utumn07 - Sunstory   -> highlight "Sunstory"
+```
+
+`src/lib/archive-grouping.ts` (shared by server and tests) folds these into a single profile with a `sources` list. Sidecars never appear as standalone archives. Each file the server returns carries its `kind`, so the client routes posts / reels / story ring / highlight circles without re-deriving naming rules.
+
+### Server-side archive index (`src/lib/archive-index.ts`)
+
+**Do not reintroduce per-request filesystem walks.** Archives typically live on network storage where per-file `stat` costs ~1.4ms and does not parallelise; a naive walk of a 110k-file root took ~52s per listing. Instead:
+
+- Each source directory is indexed once and cached, keyed by its **directory mtime** (a directory `stat` is effectively free).
+- The index is warmed in the background at startup and persisted to `CACHE_DIR` (mount a volume at `/cache`).
+- `GET /api/archives` does no file walking at all — it returns directory-mtime `signature`s, which the client uses for cache invalidation instead of a file count.
+- Only media files are stat'd (for `size`, which gates thumbnailing) and only highlights need `mtime` (their filenames carry no date).
+
+### Scanning pipeline (`src/hooks/useArchiveScanner.ts`)
+
+`handleFiles` indexes files, detects format, then parses via one of three largely independent paths that all write into a shared `postsMap`:
+
+1. **JSON manifest** (`posts_1.json`, possibly `.json.xz` via `xz-decompress`) — media matched to entries by URI, then ID, then filename heuristic, in that fallback order.
+2. **Filename patterns** — see `src/lib/archive-patterns.ts` for the export / Instaloader / highlight regexes, extracted as pure functions and covered by tests. Prefer changing them there.
+3. **Generic grouping fallback** — when nothing else matched, files sharing a basename become one carousel.
+
+Results are cached to IndexedDB. Media records store a stable `path`; **`url` is not persistable** for local archives because blob URLs die with the document.
+
+Three different JSON shapes turn up as `.json`, so they are told apart structurally, not by filename (`src/lib/gallery-dl-sidecar.ts`):
+
+| shape | marker |
+|---|---|
+| Instagram export manifest | top-level `media` array |
+| Instaloader `.json.xz` | GraphQL node under `node` / `__typename` |
+| gallery-dl sidecar | flat, `post_shortcode` + `type`, none of the above |
+
+The gallery-dl sidecar is the only source that states what a post *is*: its `type` (`post` / `reel` / `story` / `highlight`) is Instagram's own classification, so `post.isReel` set from it beats every fallback in `post-tabs.ts`. This matters — of the 781 items in `official_band - reels`, the sidecars say only **360 are reels**; the other 421 are ordinary feed videos the clips endpoint returns via `include_feed_video`. Directory-based classification counted all 781.
+
+**Dates are ranked, not last-write-wins** (`src/lib/post-dates.ts`): sidecar (what Instagram reported) beats filename (what the fetcher wrote) beats mtime (when the file hit disk, and unrelated to when it was posted). Ties keep the incumbent. Several files describe one post and they are scanned in directory order, not in order of trustworthiness, so without the ranking the date was decided by whichever file came first. Only JDownloader highlights fall to mtime at all — `parseArchiveFilename` flags those via `dateFromMtime`.
+
+### Cache and local-archive persistence (`src/lib/archive-cache.ts`)
+
+IndexedDB keys are namespaced (`archive:`, `thumb:`, `handle:`) so listing archives does not deserialize every cached thumbnail blob, and thumbnails are scoped per archive to avoid cross-archive collisions.
+
+Restoring an archive **rehydrates URLs from `path`**: server archives rebuild HTTP URLs; local archives re-open a persisted `FileSystemDirectoryHandle` and mint fresh blob URLs. If the folder is unreachable (permission lapsed, or the browser lacks `showDirectoryPicker` — Firefox/Safari), the app re-prompts rather than rendering broken images.
+
+### Thumbnails (`src/hooks/useThumbnailQueue.ts` + `src/lib/thumbnail-worker.ts`)
+
+Images over 1MiB are downscaled in a Web Worker via `OffscreenCanvas`. The queue is **serial on purpose** — decoding several 50MP+ images at once OOMs the tab. `requestThumbnail` must keep a stable identity (it reads cache state through a ref), or every completed thumbnail re-runs the effect in all mounted thumbnails.
+
+### Profile tabs (`src/lib/post-tabs.ts`)
+
+The grid holds **everything**, reels included, and the Reels tab is a *filtered view* of that same set. Only the Reels tab filters. The tabs were mutually exclusive until v1.7.0, which hid a lot: 1100 of `groupfandom`'s 3813 posts and 533 of `for.member`'s 1225 never appeared in the grid at all.
+
+This *approximates* Instagram rather than matching it. Instagram's grid includes a reel only if the creator shared it to feed — a per-post choice, measured live on 2026-08-16: `official_band` had 21 reels in its first 34 grid tiles, `4utumn07` just 1 in 214. That flag appears nowhere in an archive (JD2 stores no metadata, and Instaloader's `product_type` says what a post *is*, not whether it was shared to feed), so showing everything is the closest reachable behaviour. Instagram's "N posts" counter equals its grid, which is why the header counts `postsForTab(allPosts, 'posts')` and not `allPosts` — the raw list still holds both copies of a double-fetched post.
+
+When checking the live site, note that grid reels link to `/reel/<code>/` while ordinary posts link to `/<user>/p/<code>/`. Matching only `/p/` silently drops every reel, which once produced a confident and completely wrong conclusion that Instagram never shows reels in the grid.
+
+Deciding *what is a reel* has no good answer for most archives. Instagram's own marker is `product_type` on the post's GraphQL node (`clips` = reel, `feed` = ordinary feed video, `igtv`, `story`) — `__typename` is `GraphVideo` for all three, and aspect ratio does not separate them either. But:
+
+- Only Instaloader archives carry that metadata, and only newer captures. A survey of `hazelofficial` found `product_type` on 1101 of 5919 sidecars, and just **2** posts marked `clips`.
+- JDownloader archives carry none at all — media plus a `.txt` holding the bare caption.
+
+So the viewer believes a `- reels` sidecar directory when one exists, and otherwise falls back to treating a lone video as a reel. **The fallback is a guess**: it cannot tell a reel from a feed video or an old IGTV upload, and it misses videos inside carousels.
+
+`dedupePostCopies` exists because the JDownloader flow crawls the profile URL and the `/reels/` URL separately (the profile page misses some reels), so the two overlap and a reel can land on disk twice. Those become two posts with distinct directory-scoped ids, which the grid would otherwise render side by side. It dedupes by shortcode, preferring the reels-source copy. It is only safe over `allPosts` — stories and highlights are excluded there, and a shortcode may legitimately appear in both a profile and a highlight.
+
+### URL state (`src/App.tsx`, `src/lib/routing.ts`)
+
+Paths mirror Instagram: `/<archive>/`, `/<archive>/reels/`, `/<archive>/p/<shortcode>/`. The old `?a=&t=&p=` form is still parsed for existing links but never written. Reserved prefixes (`api`, `archives`, `assets`…) can't be mistaken for a profile name.
+
+A post URL carries no tab, as on Instagram — the tab is re-derived from the post's `source`, so a reel link lands on the Reels tab and pages through reels. Sidecar posts keep directory-scoped ids internally but expose only the shortcode.
+
+Three rules, all learned from real bugs:
+
+- The initial route is captured into a ref on first render; the URL is rewritten from state as soon as anything loads, so reading `window.location` later sees the rewrite, not the user's link.
+- URL writing is gated on `hasInitialLoaded`, otherwise it erases the deep link before the loader consumes it.
+- Deep-link resolution waits on the archive fetch having *settled* (`archivesFetched`), not on `isServerMode`, which is still false while the request is in flight.
+
+### Mobile feed (`src/components/PostFeed.tsx`)
+
+Below `md`, opening a post renders a scrolling feed page rather than the modal (`useIsMobile` decides). Only a window of posts is mounted; it grows both ways, and prepending corrects `scrollTop` in a `useLayoutEffect` so content doesn't jump. Only the post crossing the viewport centre plays its video and drives the URL. Desktop keeps `PostModal`; both share `MediaCarousel`.
+
+### Backend (`server.ts`)
+
+Serves `/api/archives`, `/api/archives/:name/files`, static `/archives`, and the built SPA. Notes:
+
+- Express decodes route params **after** segment matching, so `..%2f` reaches the handler as `../`. All user-supplied archive names go through `resolveArchivePath`.
+- `os.userInfo()` throws for a UID with no `/etc/passwd` entry, which is what `--user 1234:1234` produces — use `describeUser()`.
+
+### CSP: do not tighten `script-src` or `connect-src` without testing xz
+
+The xz decompressor for Instaloader `.json.xz` sidecars is **WebAssembly**, embedded as a `data:` URL the library fetches at startup. The policy must keep:
+
+```
+script-src  'self' 'wasm-unsafe-eval'     // compile wasm, without allowing eval() of JS
+connect-src 'self' data:                  // fetch the embedded module
+```
+
+Removing either breaks decoding with a bare `TypeError: Failed to fetch` **and no stack** — it surfaces through `new Response(stream).json()`, so it reads like a network fault rather than a policy block. The visible symptom is not an error page: archives silently lose captions, story flags and all profile metadata (follower counts, bio, name). This shipped broken for several releases.
+
+To check quickly, run in the page console:
+
+```js
+await fetch('data:application/wasm;base64,AGFzbQEAAAA=')            // connect-src
+await WebAssembly.instantiate(Uint8Array.of(0,97,115,109,1,0,0,0))  // script-src
+```
+
+**The Vite dev server does not send these headers**, so anything CSP-related is invisible in `npm run dev`. Verify security-header and PWA behaviour by building and serving `dist/` through `server.js`, not against the dev server.
+
+### PWA: server-only changes do not reach installed clients
+
+The service worker precaches `index.html` **together with its response headers**. A change that touches only the server (a CSP fix, a new header) leaves the client build byte-identical, so the precache manifest and `sw.js` are unchanged, the worker never updates, and installed clients keep replaying the old shell with the old headers — indefinitely.
+
+`vite.config.ts` therefore compiles the package version into the client via `define: { __APP_VERSION__ }`, and `App.tsx` renders it in the footer. That is **load-bearing**: it makes every release change the bundle hash → `index.html` → its precache revision → `sw.js`, which is what browsers byte-compare to decide whether to update. Don't remove it as dead weight.
+
+To recover a client stuck on an old shell: unregister the service worker, delete its caches, reload.
+
+### Deployment
+
+Live archives live in `<share>/Instagram-archive/archives/` — one directory per profile plus sidecars. Directories that are not Instagram profiles (tool output, exports from other services) sit *outside* that folder so they never reach the viewer.
+
+Container runs as non-root. The image defaults to `node`, but the archive share must be *listable* by that UID — a mode-711 share owned by another account needs `user: "<uid>:<gid>"` in compose. Mount a volume at `/cache` so the index survives restarts.
+
+### PWA / build quirks
+
+- `vite.config.ts` sets `hmr: process.env.DISABLE_HMR !== 'true'` — intentional, leave it.
+- `workbox.navigateFallbackDenylist` excludes `/api` and `/archives` so those hit the real server.
+- Fonts and icons are vendored in `public/` — do not reintroduce CDN references; the app advertises offline support and local-only processing.

Dockerfile

@@ -18,6 +18,9 @@ FROM node:20-slim AS runtime
 ENV NODE_ENV=production
 ENV PORT=3000
 ENV ARCHIVES_DIR=/archives
+# Where the archive index is persisted; mount a volume here so a restart does
+# not have to re-walk the whole archive root.
+ENV CACHE_DIR=/cache
 
 WORKDIR /app
 
@@ -25,12 +28,16 @@ WORKDIR /app
 COPY package*.json ./
 RUN npm ci --omit=dev
 
-# Copy built assets and server
+# Copy built assets and server. The whole dist-server tree is needed: the
+# server imports shared archive-grouping logic emitted alongside it.
 COPY --from=build /app/dist ./dist
-COPY --from=build /app/dist-server/server.js ./server.js
+COPY --from=build /app/dist-server/ ./
 
-# Ensure archives directory exists
-RUN mkdir -p /archives
+# Ensure archives and cache directories exist, writable by the runtime user.
+RUN mkdir -p /archives /cache && chown node:node /cache
+
+# Drop root: the server reads the archives volume and writes only its index.
+USER node
 
 EXPOSE 3000
 

GEMINI.md

@@ -5,37 +5,65 @@
 **InstaArchive** is a high-performance, React-based Progressive Web App (PWA) designed to browse and explore archived Instagram data with a native-feeling interface. It supports both local directory loading and self-hosted server modes.
 
 ### Key Technical Features
-- **Persistent Caching:** Uses `idb-keyval` (IndexedDB) to cache parsed metadata and server-side media URLs. Subsequent loads of the same archive are instant.
-- **Glassy Scanner UI:** A custom-built glassmorphism scanning dashboard with throttled (1s) dynamic blurred backgrounds and a high-density system log.
-- **Support for Multiple Formats:** Recognizes official Instagram export structures and Instaloader regex-based naming conventions.
-- **Compressed Metadata:** Support for `.json.xz` file decompression using `xz-decompress` (WASM-powered).
-- **Navigation Protection:** Intercepts browser history (`popstate`) and exit events (`beforeunload`) to prevent session loss while maintaining a "Back to Explorer" SPA flow.
-- **Production-Ready Docker:** Multi-stage Docker builds using `node:slim` to serve both the Express API and the Vite-built frontend.
+- **Permalinks:** Full synchronization between application state and URL query parameters (`?a=`, `?t=`, `?p=`). Supports deep-linking to archives, tabs, and specific posts. URL parameters are automatically cleaned when navigating back to the archive explorer.
+- **Persistent Caching:** Uses `idb-keyval` (IndexedDB) to cache parsed metadata. Subsequent loads are near-instant.
+  - **Metadata:** Caches profile info and post lists for both remote AND local archives.
+  - **Thumbnails:** High-res images (>1MiB) and videos have thumbnails generated and cached in IndexedDB with the `thumb_` prefix.
+- **Background Media Processing:**
+  - **High-Res Images:** A dedicated Web Worker (`thumbnail-worker.ts`) handles image resizing using `OffscreenCanvas` and `createImageBitmap` to prevent main-thread jank.
+  - **Serial Queue:** A memory-safe queue ensures only one high-res image is decoded at a time, preventing Out-of-Memory (OOM) crashes on 50MP+ files.
+- **High-Performance Carousel:** Advanced `PostModal` with:
+  - **Inter-Post Preloading:** Preloads the first media of adjacent posts for instant navigation.
+  - **Intra-Carousel Preloading:** Intelligently preloads the current carousel's slides.
+  - **Seamless Transitions:** Zero-latency slide transitions without "black flashes" between images.
+- **Glassy Scanner UI:** Custom-built glassmorphism scanning dashboard with double-buffering logic to ensure smooth, flicker-free background crossfades during file indexing.
+- **PWA Capabilities:** 
+  - **Auto-Updates:** Hourly periodic update checks.
+  - **Navigation Fix:** `navigateFallbackDenylist` allows direct server access to `/archives/` and `/api/` (enabling "Open in new tab" for original files).
 
 ### Main Technologies
-- **Frontend:** React 19, Vite, TypeScript
+- **Frontend:** React 19, Vite 6, TypeScript
 - **Styling:** Tailwind CSS (v4)
 - **Icons:** Lucide React
 - **Animations:** Framer Motion (`motion/react`)
 - **Persistence:** IndexedDB (`idb-keyval`)
-- **Backend:** Express, tsx (for server-side scanning)
-- **Decompression:** xz-decompress (WASM)
+- **Backend:** Express, tsx
+- **Workers:** Web Workers for background image processing.
+
+## Architecture
+
+### State Management
+- **`useArchiveScanner` Hook:** Centralized logic for parsing and caching. It handles folder-name-to-username detection and "Smart Fallback" profile pictures (using the oldest image if no profile pic is found).
+- **`useThumbnailQueue` Hook:** Manages the serial processing of high-resolution media.
+
+### Cache Schema
+```typescript
+interface CacheData {
+  name: string;
+  isLocal: boolean;
+  fileCount: number;
+  posts: Post[];      // Cached for all archive types
+  stories: Post[];
+  profileMetadata: {
+    username: string;
+    fullName: string;
+    bio: string;
+    followerCount: number;
+    followingCount: number;
+    externalUrl: string;
+    profilePic: string | null;
+    allProfilePics: string[];
+  };
+  timestamp: number;
+}
+```
 
 ## Commands
-- `npm install`: Install project dependencies.
-- `npm run dev`: Start the local development server on port 3000.
-- `npm run build`: Generate the production-ready build in the `dist` folder.
-- `npm run server`: Start the backend server to scan `./_sample-archives`.
+- `npm install`: Install dependencies.
+- `npm run dev`: Start dev server (Port 3000).
+- `npm run build`: Build frontend (`dist/`) and server (`dist-server/`).
+- `npm run server`: Start production-ready backend.
 - `npm run lint`: Execute TypeScript type-checking.
 
 ## Production Deployment
-The project is containerized and available on GHCR. It expects a volume mount at `/archives` containing subdirectories for each user.
-
-### Key Environment Variables
-- `PORT`: Server port (default: 3000)
-- `ARCHIVES_DIR`: Path to the archives collection (default: /archives)
-
-## Development Conventions
-- **Username Logic:** The directory name is the definitive source of truth for the account username.
-- **State Management:** React `useState`, `useMemo`, and `useCallback` for optimized performance.
-- **File Handling:** Uses `RemoteArchiveFile` and `LocalArchiveFile` classes to provide a unified `ArchiveFile` interface for the parser.
+The project is containerized. It expects a volume mount at `/archives` containing subdirectories for each user.

README.md

@@ -4,12 +4,16 @@ A high-performance React PWA for browsing archived Instagram data with a native-
 
 ## Features
 
-- **Persistent Caching**: Uses IndexedDB to store parsed archives locally. Subsequent loads are near-instant.
-- **Glassy Scanning UI**: A modern, translucent white terminal experience with a dynamic blurred background of your media.
-- **Local Privacy**: All processing is done client-side. Even when using the self-hosted version, your media is processed locally in your browser.
-- **Multiple Formats**: Supports official Instagram JSON exports and Instaloader regex-based naming conventions.
-- **Story Viewer**: Native-like story experience with segmented progress bars, auto-playback, and audio controls.
+- **Advanced Carousel**: Seamless, zero-latency transitions between slides with intelligent preloading. Navigating between different posts is now near-instant thanks to inter-post background preloading.
+- **High-Res Performance**: Handles 50MP+ images effortlessly using a background Web Worker and a memory-safe serial processing queue.
+- **Persistent Local Caching**: Uses IndexedDB to store parsed archives and generated thumbnails. **Local folders** now load instantly from cache on return visits without needing to re-upload files.
+- **Permalinks**: State is synchronized with the URL, allowing you to share direct links to archives, tabs, or specific posts. Navigating back to the explorer cleans up URL parameters automatically.
+- **Glassy Scanning UI**: A refined, translucent white terminal experience with flicker-free, double-buffered dynamic blurred backgrounds.
+- **PWA with Auto-Update**: Fully offline-capable and installable. Clients automatically receive updates when a new version is deployed to the server.
+- **Local Privacy**: All processing is done client-side. Even when using the self-hosted version, your media is processed locally in your browser and never uploaded.
+- **Smart Fallbacks**: Automatically detects usernames from folder names and uses the oldest archive image as a profile picture if one is missing.
 - **Customizable Grid**: 1:1 or 3:4 aspect ratios with adjustable "bumps" for aesthetic alignment.
+- **Story Viewer**: Native-like story experience with segmented progress bars, auto-playback, and audio controls.
 - **Navigation Protection**: Intercepts accidental browser "Back" or "Refresh" actions to protect your current session.
 
 ## Deployment
@@ -50,10 +54,27 @@ If the app shows "No Archives Found" and logs `EACCES: permission denied`:
    chmod -R 755 /path/to/archives
    ```
 2. **SELinux (Fedora/RHEL/CentOS)**: Use the `:z` flag in your volume mount as shown above.
-3. **User Mapping**: You can force the container to run as your host user:
+3. **User Mapping**: The container runs as the non-root `node` user (UID 1000).
+   If your archives are readable only by another account, run as that user
+   instead — the container needs to *list* the archive directory, so `--x`
+   (traverse-only) permissions are not enough:
    ```bash
-   docker run --user $(id -u):$(id -g) ...
+   docker run --user $(stat -c '%u:%g' /path/to/archives) ...
    ```
+   In Compose:
+   ```yaml
+   services:
+     instaarchive:
+       user: "1234:1234"   # a UID that can read your archives
+   ```
+
+### Archive Index
+
+On first start the server walks the archive root once and caches the result,
+keyed by directory mtime. This matters on network storage: for a 110k-file
+archive root, listing went from ~52s per request to ~0.1s. Mount a volume at
+`/cache` (or set `CACHE_DIR`) so the index survives restarts, otherwise it is
+rebuilt on every start.
 
 ## Supported Archive Structure
 
@@ -77,5 +98,6 @@ archives/
 **Prerequisites:** Node.js (LTS recommended)
 
 1. **Install dependencies:** `npm install`
-2. **Start dev server:** `npm run dev`
-3. **Start local backend:** `npm run server` (Optional, serves `./_sample-archives`)
+2. **Start dev server:** `npm run dev` (Frontend on port 3000)
+3. **Start local backend:** `npm run server` (Optional, serves `./_sample-archives` on port 3001)
+4. **Build production:** `npm run build` (Generates `./dist` for frontend and `./dist-server` for the API)

compose.yml

@@ -5,7 +5,13 @@ services:
       - "3000:3000"
     volumes:
       - ./archives:/archives:ro,z
+      # Persists the archive index so restarts don't re-walk every file.
+      - instaarchive-cache:/cache
     environment:
       - PORT=3000
       - ARCHIVES_DIR=/archives
+      - CACHE_DIR=/cache
     restart: unless-stopped
+
+volumes:
+  instaarchive-cache:

package.json

@@ -1,22 +1,22 @@
 {
-  "name": "react-example",
+  "name": "instaarchive-viewer",
   "private": true,
-  "version": "1.1.2",
+  "version": "1.8.1",
   "type": "module",
   "scripts": {
     "dev": "vite --port=3000 --host=0.0.0.0",
     "build": "vite build && npm run build:server",
-    "build:server": "tsc server.ts --esModuleInterop --module ESNext --target ES2022 --moduleResolution bundler --outDir dist-server",
+    "build:server": "tsc server.ts --esModuleInterop --module ESNext --target ES2022 --moduleResolution bundler --removeComments --outDir dist-server",
     "preview": "vite preview",
     "server": "tsx server.ts",
     "clean": "rm -rf dist",
-    "lint": "tsc --noEmit"
+    "lint": "tsc --noEmit",
+    "test": "vitest run",
+    "test:watch": "vitest"
   },
   "dependencies": {
-    "@google/genai": "^1.29.0",
     "@tailwindcss/vite": "^4.1.14",
     "@vitejs/plugin-react": "^5.0.4",
-    "better-sqlite3": "^12.4.1",
     "clsx": "^2.1.1",
     "date-fns": "^4.1.0",
     "dotenv": "^17.2.3",
@@ -34,10 +34,13 @@
   "devDependencies": {
     "@types/express": "^4.17.21",
     "@types/node": "^22.14.0",
+    "@types/react": "^19.2.18",
+    "@types/react-dom": "^19.2.4",
     "autoprefixer": "^10.4.21",
     "tailwindcss": "^4.1.14",
     "typescript": "~5.8.2",
     "vite": "^6.2.0",
-    "vite-plugin-pwa": "^1.2.0"
+    "vite-plugin-pwa": "^1.2.0",
+    "vitest": "^3.2.7"
   }
 }

public/fonts/fonts.css

@@ -0,0 +1,56 @@
+/* Self-hosted subset of Inter + Playfair Display.
+   Vendored so the PWA works offline and makes no third-party requests. */
+/* latin-ext */
+@font-face {
+  font-family: 'Inter';
+  font-style: normal;
+  font-weight: 300 700;
+  font-display: swap;
+  src: url(/fonts/inter-300_700-normal-b6db4a.woff2) format('woff2');
+  unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
+}
+/* latin */
+@font-face {
+  font-family: 'Inter';
+  font-style: normal;
+  font-weight: 300 700;
+  font-display: swap;
+  src: url(/fonts/inter-300_700-normal-6ab57b.woff2) format('woff2');
+  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
+}
+/* latin-ext */
+@font-face {
+  font-family: 'Playfair Display';
+  font-style: italic;
+  font-weight: 400 900;
+  font-display: swap;
+  src: url(/fonts/playfair-display-400_900-italic-2d6d99.woff2) format('woff2');
+  unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
+}
+/* latin */
+@font-face {
+  font-family: 'Playfair Display';
+  font-style: italic;
+  font-weight: 400 900;
+  font-display: swap;
+  src: url(/fonts/playfair-display-400_900-italic-d14361.woff2) format('woff2');
+  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
+}
+/* latin-ext */
+@font-face {
+  font-family: 'Playfair Display';
+  font-style: normal;
+  font-weight: 400 900;
+  font-display: swap;
+  src: url(/fonts/playfair-display-400_900-normal-ca7410.woff2) format('woff2');
+  unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
+}
+/* latin */
+@font-face {
+  font-family: 'Playfair Display';
+  font-style: normal;
+  font-weight: 400 900;
+  font-display: swap;
+  src: url(/fonts/playfair-display-400_900-normal-61a963.woff2) format('woff2');
+  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
+}

server.ts

@@ -4,6 +4,7 @@ import path from 'path';
 import { fileURLToPath } from 'url';
 import dotenv from 'dotenv';
 import os from 'os';
+import { ArchiveIndex } from './src/lib/archive-index.js';
 
 dotenv.config();
 
@@ -15,7 +16,23 @@ const PORT = process.env.PORT || 3001;
 const ARCHIVES_DIR = path.resolve(process.env.ARCHIVES_DIR || path.join(__dirname, '_sample-archives'));
 
 console.log(`[Server] Initializing...`);
-console.log(`[Server] Running as user: ${os.userInfo().username} (UID: ${os.userInfo().uid}, GID: ${os.userInfo().gid})`);
+/**
+ * Describe the running user without assuming it exists in /etc/passwd.
+ *
+ * `os.userInfo()` throws ENOENT for a UID with no passwd entry, which is
+ * exactly what happens when the container is started with `--user 1234:1234`
+ * (as the deployment docs suggest) — previously crashing the server at boot.
+ */
+const describeUser = () => {
+  try {
+    const info = os.userInfo();
+    return `${info.username} (UID: ${info.uid}, GID: ${info.gid})`;
+  } catch {
+    return `UID: ${typeof process.getuid === 'function' ? process.getuid() : '?'}, GID: ${typeof process.getgid === 'function' ? process.getgid() : '?'} (no passwd entry)`;
+  }
+};
+
+console.log(`[Server] Running as user: ${describeUser()}`);
 console.log(`[Server] Environment ARCHIVES_DIR: ${process.env.ARCHIVES_DIR}`);
 console.log(`[Server] Resolved ARCHIVES_DIR: ${ARCHIVES_DIR}`);
 
@@ -31,55 +48,95 @@ if (!fs.existsSync(ARCHIVES_DIR)) {
   console.log(`[Server] Archives directory exists.`);
 }
 
+const INDEX_PATH = process.env.ARCHIVE_INDEX_PATH
+  || path.join(process.env.CACHE_DIR || os.tmpdir(), 'instaarchive-index.json');
+const index = new ArchiveIndex(ARCHIVES_DIR, INDEX_PATH);
+
+// Warm in the background: the first walk of a large archive root is slow, but
+// everything after it is served from directory-mtime-keyed cache.
+index.load()
+  .then(() => index.warm())
+  .catch(err => console.error('[Index] Warm failed:', err));
+
+// Don't advertise the framework.
+app.disable('x-powered-by');
+
+/**
+ * Baseline security headers.
+ *
+ * The CSP allows blob: and data: because archive media is rendered from object
+ * URLs and cached thumbnails, and 'unsafe-inline' for styles because the
+ * animation library sets inline styles. Scripts stay restricted to same-origin,
+ * and no third-party origins are permitted at all — the app bundles its own
+ * fonts and icons.
+ */
+app.use((req, res, next) => {
+  res.setHeader('X-Content-Type-Options', 'nosniff');
+  res.setHeader('X-Frame-Options', 'SAMEORIGIN');
+  res.setHeader('Referrer-Policy', 'no-referrer');
+  res.setHeader('Cross-Origin-Resource-Policy', 'same-origin');
+  res.setHeader('Permissions-Policy', 'geolocation=(), microphone=(), camera=(), interest-cohort=()');
+  res.setHeader('Content-Security-Policy', [
+    "default-src 'self'",
+    "img-src 'self' blob: data:",
+    "media-src 'self' blob: data:",
+    // 'wasm-unsafe-eval' permits WebAssembly compilation without allowing
+    // eval() of JavaScript. The xz decompressor used for Instaloader's
+    // .json.xz sidecars is WebAssembly, embedded as a data: URL it fetches at
+    // startup — so connect-src must allow data: too. Without both, decoding
+    // fails with a bare "TypeError: Failed to fetch" and every archive silently
+    // loses its captions, story flags and profile metadata.
+    "script-src 'self' 'wasm-unsafe-eval'",
+    "style-src 'self' 'unsafe-inline'",
+    "font-src 'self'",
+    "connect-src 'self' data:",
+    "worker-src 'self' blob:",
+    "frame-ancestors 'self'",
+    "object-src 'none'",
+    "base-uri 'self'",
+    "form-action 'self'",
+  ].join('; '));
+  next();
+});
+
 app.use(express.json());
 
-// API: List archives (subdirectories in ARCHIVES_DIR)
-app.get('/api/archives', (req, res) => {
-  try {
-    console.log(`[API] Listing archives from ${ARCHIVES_DIR}...`);
-    const items = fs.readdirSync(ARCHIVES_DIR, { withFileTypes: true });
-    console.log(`[API] Found ${items.length} total items in archives directory.`);
-    
-    const archives = items
-      .filter(item => {
-        const isDir = item.isDirectory();
-        if (!isDir) console.log(`[API] Skipping non-directory: ${item.name}`);
-        return isDir;
-      })
-      .map(item => {
-        // Try to find a profile pic or first image for the thumbnail
-        const archivePath = path.join(ARCHIVES_DIR, item.name);
-        try {
-          const files = fs.readdirSync(archivePath);
-          console.log(`[API] Found archive: ${item.name} (${files.length} files)`);
-          
-          let thumbnail = '';
-          const profilePic = files.find(f => f.toLowerCase().includes('_profile_pic.jpg') || f.toLowerCase() === `${item.name.toLowerCase()}.jpg`);
-          if (profilePic) {
-            thumbnail = `/archives/${item.name}/${profilePic}`;
-          } else {
-            const firstImage = files.find(f => /\.(jpg|jpeg|png|webp)$/i.test(f));
-            if (firstImage) thumbnail = `/archives/${item.name}/${firstImage}`;
-          }
-
-          return {
-            name: item.name,
-            thumbnail,
-            path: item.name,
-            fileCount: files.length
-          };
-        } catch (e) {
-          console.error(`[API] Could not read subdirectory ${item.name}:`, e);
+/**
+ * Resolve a user-supplied archive name to an absolute path inside ARCHIVES_DIR.
+ *
+ * Express decodes route params *after* segment matching, so a name like
+ * `..%2f..%2fetc` arrives here as `../../etc` and would otherwise escape the
+ * archives root. Returns null for anything that resolves outside it.
+ */
+const resolveArchivePath = (archiveName: string): string | null => {
+  if (!archiveName || archiveName.includes('\0')) return null;
+  const resolved = path.resolve(ARCHIVES_DIR, archiveName);
+  if (resolved !== ARCHIVES_DIR && !resolved.startsWith(ARCHIVES_DIR + path.sep)) {
+    console.warn(`[Security] Rejected archive name escaping ARCHIVES_DIR: ${archiveName}`);
     return null;
   }
-      })
-      .filter(Boolean);
+  return resolved;
+};
 
-    console.log(`[API] Returning ${archives.length} validated archives.`);
+// API: List archives, grouped by profile. Costs one stat per source directory.
+app.get('/api/archives', (req, res) => {
+  try {
+    const groups = index.groups();
+    const archives = Array.from(groups.entries()).map(([owner, sources]) => ({
+      name: owner,
+      thumbnail: index.thumbnailFor(owner, sources),
+      path: owner,
+      // Null until that profile has been indexed; the client treats it as unknown.
+      fileCount: index.countFor(sources),
+      // Directory mtimes: cheap to compute and enough to invalidate a stale cache.
+      signature: index.signatureFor(sources),
+      sources,
+    }));
+    console.log(`[API] Returning ${archives.length} archives.`);
     res.json(archives);
   } catch (err: any) {
     if (err.code === 'EACCES') {
-      console.error(`[API] Permission Denied! The server (UID ${os.userInfo().uid}) cannot read ${ARCHIVES_DIR}.`);
+      console.error(`[API] Permission Denied! The server (${describeUser()}) cannot read ${ARCHIVES_DIR}.`);
       console.error(`[API] Hint: If using Linux/Docker, check folder permissions (chmod 755) or SELinux context (append :z to your volume mount).`);
     } else {
       console.error('[API] Error listing archives:', err);
@@ -88,33 +145,26 @@ app.get('/api/archives', (req, res) => {
   }
 });
 
-// API: List all files in an archive (recursive)
-app.get('/api/archives/:name/files', (req, res) => {
+/**
+ * List every file belonging to a profile, across its base and sidecar dirs.
+ *
+ * Paths are relative to ARCHIVES_DIR (so they include the source directory) and
+ * each entry carries its source kind, letting the client route posts, reels,
+ * stories and highlights without re-deriving the naming rules.
+ *
+ * Served from the directory index; only a directory whose mtime changed is
+ * re-walked.
+ */
+app.get('/api/archives/:name/files', async (req, res) => {
   const archiveName = req.params.name;
-  const archivePath = path.join(ARCHIVES_DIR, archiveName);
-
-  if (!fs.existsSync(archivePath)) {
-    return res.status(404).json({ error: 'Archive not found' });
+  if (!resolveArchivePath(archiveName)) {
+    return res.status(400).json({ error: 'Invalid archive name' });
   }
 
   try {
-    const walk = (dir: string, base: string = ''): string[] => {
-      let results: string[] = [];
-      const list = fs.readdirSync(dir);
-      list.forEach(file => {
-        const filePath = path.join(dir, file);
-        const relativePath = path.join(base, file);
-        const stat = fs.statSync(filePath);
-        if (stat && stat.isDirectory()) {
-          results = results.concat(walk(filePath, relativePath));
-        } else {
-          results.push(relativePath);
-        }
-      });
-      return results;
-    };
-
-    const files = walk(archivePath);
+    const files = await index.filesFor(archiveName);
+    if (!files) return res.status(404).json({ error: 'Archive not found' });
+    void index.save();
     res.json(files);
   } catch (err) {
     console.error('Error listing files:', err);
@@ -122,8 +172,14 @@ app.get('/api/archives/:name/files', (req, res) => {
   }
 });
 
-// Serve archive files
-app.use('/archives', express.static(ARCHIVES_DIR));
+// Serve archive files. Archive contents are immutable in practice, so cache
+// them aggressively; the client busts its own cache via fileCount.
+app.use('/archives', express.static(ARCHIVES_DIR, {
+  maxAge: '1y',
+  immutable: true,
+  index: false,
+  dotfiles: 'ignore',
+}));
 
 // Serve production frontend
 const distPath = path.join(__dirname, 'dist');

src/components/ArchiveDashboard.tsx

@@ -0,0 +1,155 @@
+import React from 'react';
+import { 
+  FolderOpen, 
+  Grid3X3, 
+  Play, 
+  Trash2, 
+  Zap 
+} from 'lucide-react';
+import { CacheData, ServerArchive } from '../types';
+
+interface ArchiveDashboardProps {
+  archives: ServerArchive[];
+  localArchives?: CacheData[];
+  cachedArchives: Set<string>;
+  onSelect: (archive: ServerArchive) => void;
+  onLocalSelect: () => void;
+  onLocalCacheSelect: (archive: CacheData) => void;
+  onClearCache: (name: string) => void;
+  isScanning: boolean;
+}
+
+export const ArchiveDashboard: React.FC<ArchiveDashboardProps> = ({ 
+  archives, 
+  localArchives = [],
+  cachedArchives,
+  onSelect,
+  onLocalSelect,
+  onLocalCacheSelect,
+  onClearCache,
+  isScanning
+}) => {
+  return (
+    <div className="max-w-6xl mx-auto px-4 py-12 space-y-12">
+      <div className="text-center space-y-4">
+        <h2 className="text-4xl font-bold tracking-tight font-serif italic text-black/80">Archive Explorer</h2>
+        <p className="text-gray-500 max-w-xl mx-auto text-sm md:text-base leading-relaxed">
+          Browse hosted collections or open a local archive folder. All processing happens locally in your browser for maximum privacy.
+        </p>
+      </div>
+
+      <div className="grid grid-cols-2 md:grid-cols-3 lg:grid-cols-4 gap-4 md:gap-8">
+        {/* Local Folder Card */}
+        <button 
+          onClick={onLocalSelect}
+          disabled={isScanning}
+          className="aspect-[3/4] rounded-xl border-2 border-dashed border-gray-200 hover:border-blue-400 hover:bg-blue-50/50 transition-all flex flex-col items-center justify-center gap-4 group disabled:opacity-50 text-black"
+        >
+          <div className="w-12 h-12 rounded-full bg-gray-100 group-hover:bg-blue-100 flex items-center justify-center text-gray-400 group-hover:text-blue-500 transition-colors shadow-inner">
+            <FolderOpen size={24} />
+          </div>
+          <div className="text-center px-4">
+            <span className="font-bold text-sm block text-black/80">Open Local Folder</span>
+            <span className="text-[10px] text-gray-400 uppercase tracking-widest leading-tight block mt-1">Processed in Browser</span>
+          </div>
+        </button>
+
+        {/* Server Archives */}
+        {archives.map((archive) => {
+          const isCached = cachedArchives.has(archive.name);
+          return (
+            <div key={archive.path} className="relative group text-black">
+              <button
+                onClick={() => onSelect(archive)}
+                disabled={isScanning}
+                className="w-full aspect-[3/4] rounded-xl overflow-hidden bg-white shadow-sm border border-gray-100 hover:shadow-xl hover:scale-[1.02] transition-all flex flex-col text-left disabled:opacity-50"
+              >
+                <div className="flex-1 bg-gray-100 overflow-hidden relative">
+                  {archive.thumbnail ? (
+                    <img src={archive.thumbnail} alt="" className="w-full h-full object-cover" />
+                  ) : (
+                    <div className="w-full h-full flex items-center justify-center text-gray-300">
+                      <Grid3X3 size={48} strokeWidth={1} />
+                    </div>
+                  )}
+                  <div className="absolute inset-0 bg-black/20 opacity-0 hover:opacity-100 transition-opacity flex items-center justify-center">
+                    <Play size={32} fill="white" className="text-white" />
+                  </div>
+                  
+                  {isCached && (
+                    <div className="absolute top-2 left-2 bg-blue-500 text-white p-1 rounded-md shadow-lg flex items-center gap-1 text-[8px] font-bold uppercase tracking-wider z-10 pr-2 opacity-0 group-hover:opacity-100 transition-all">
+                      <Zap size={10} fill="currentColor" />
+                      Cached
+                    </div>
+                  )}
+                </div>
+                <div className="p-4 space-y-1">
+                  <span className="font-bold text-sm block truncate uppercase tracking-tight text-black/80">{archive.name}</span>
+                  <span className="text-[10px] text-gray-400 uppercase tracking-widest">
+                    {archive.fileCount === null
+                      ? `${archive.sources?.length ?? 1} source${(archive.sources?.length ?? 1) === 1 ? '' : 's'}`
+                      : `${archive.fileCount} items`}
+                  </span>
+                </div>
+              </button>
+              
+              {isCached && (
+                <button
+                  onClick={(e) => {
+                    e.stopPropagation();
+                    onClearCache(archive.name);
+                  }}
+                  className="absolute top-2 right-2 p-2 bg-white/90 hover:bg-red-50 hover:text-red-500 text-gray-400 rounded-lg shadow-sm opacity-0 group-hover:opacity-100 transition-all z-20"
+                  title="Clear Cache"
+                >
+                  <Trash2 size={14} />
+                </button>
+              )}
+            </div>
+          );
+        })}
+
+        {/* Local Cached Archives */}
+        {localArchives.map((archive) => (
+          <div key={archive.name} className="relative group text-black">
+            <button
+              onClick={() => onLocalCacheSelect(archive)}
+              disabled={isScanning}
+              className="w-full aspect-[3/4] rounded-xl overflow-hidden bg-white shadow-sm border border-gray-100 hover:shadow-xl hover:scale-[1.02] transition-all flex flex-col text-left disabled:opacity-50"
+            >
+              <div className="flex-1 bg-gray-100 overflow-hidden relative text-black">
+                {archive.profileMetadata.profilePic ? (
+                  <img src={archive.profileMetadata.profilePic} alt="" className="w-full h-full object-cover" />
+                ) : (
+                  <div className="w-full h-full flex items-center justify-center text-gray-300">
+                    <Grid3X3 size={48} strokeWidth={1} />
+                  </div>
+                )}
+                <div className="absolute inset-0 bg-black/20 opacity-0 hover:opacity-100 transition-opacity flex items-center justify-center">
+                  <FolderOpen size={32} fill="white" className="text-white" />
+                </div>
+                <div className="absolute bottom-2 left-2 bg-gray-800/80 text-white px-2 py-0.5 rounded text-[8px] font-bold uppercase tracking-widest backdrop-blur-sm">
+                  Local Cache
+                </div>
+              </div>
+              <div className="p-4 space-y-1 text-black">
+                <span className="font-bold text-sm block truncate uppercase tracking-tight text-black/80">{archive.name}</span>
+                <span className="text-[10px] text-gray-400 uppercase tracking-widest">{archive.fileCount} indexed</span>
+              </div>
+            </button>
+            <button
+              onClick={(e) => {
+                e.stopPropagation();
+                onClearCache(archive.name);
+              }}
+              className="absolute top-2 right-2 p-2 bg-white/90 hover:bg-red-50 hover:text-red-500 text-gray-400 rounded-lg shadow-sm opacity-0 group-hover:opacity-100 transition-all z-20"
+              title="Clear Cache"
+            >
+              <Trash2 size={14} />
+            </button>
+          </div>
+        ))}
+      </div>
+    </div>
+  );
+};

src/components/ErrorBoundary.tsx

@@ -0,0 +1,55 @@
+import React from 'react';
+import { AlertTriangle } from 'lucide-react';
+
+interface Props { children: React.ReactNode }
+interface State { error: Error | null }
+
+/**
+ * Keeps one bad archive item from blanking the whole app.
+ *
+ * Post data is derived from filenames and arbitrary archive JSON, so a single
+ * malformed record used to be able to throw during render and take the entire
+ * tree down with it.
+ */
+export class ErrorBoundary extends React.Component<Props, State> {
+  constructor(props: Props) {
+    super(props);
+    this.state = { error: null };
+  }
+
+  static getDerivedStateFromError(error: Error): State {
+    return { error };
+  }
+
+  componentDidCatch(error: Error, info: React.ErrorInfo) {
+    console.error('[ErrorBoundary] Render failed:', error, info.componentStack);
+  }
+
+  render() {
+    if (!this.state.error) return this.props.children;
+
+    return (
+      <div className="min-h-screen bg-gray-50 flex items-center justify-center p-6">
+        <div className="max-w-md w-full bg-white rounded-2xl shadow-sm border border-gray-100 p-8 space-y-4 text-center">
+          <div className="w-12 h-12 mx-auto rounded-full bg-red-50 text-red-500 flex items-center justify-center">
+            <AlertTriangle size={24} />
+          </div>
+          <h2 className="text-xl font-semibold text-black/80">Something went wrong</h2>
+          <p className="text-sm text-gray-500">
+            This archive could not be rendered. Reloading usually clears it; if it
+            persists, clear the cached copy from the archive explorer.
+          </p>
+          <pre className="text-[11px] text-left text-gray-400 bg-gray-50 rounded-lg p-3 overflow-x-auto">
+            {this.state.error.message}
+          </pre>
+          <button
+            onClick={() => window.location.reload()}
+            className="bg-blue-500 hover:bg-blue-600 text-white px-6 py-2 rounded-lg text-sm font-semibold transition-colors"
+          >
+            Reload
+          </button>
+        </div>
+      </div>
+    );
+  }
+}

src/components/FeedPost.tsx

@@ -0,0 +1,67 @@
+import React from 'react';
+import { Bookmark, Heart, MessageCircle, MoreHorizontal, Send } from 'lucide-react';
+import { Post } from '../types';
+import { formatDateSafe } from '../lib/utils';
+import { MediaCarousel } from './MediaCarousel';
+
+interface FeedPostProps {
+  post: Post;
+  profilePic: string | null;
+  /** Off-screen posts keep their video paused. */
+  paused: boolean;
+}
+
+/**
+ * One post in the mobile feed, laid out like Instagram's: header, media,
+ * action row, then caption.
+ *
+ * Media is capped below full viewport height so the next post always peeks in
+ * at the bottom — that overlap is what tells you the page scrolls rather than
+ * pages.
+ */
+export const FeedPost: React.FC<FeedPostProps> = ({ post, profilePic, paused }) => (
+  <article className="bg-white border-b border-gray-200">
+    <header className="flex items-center justify-between px-3 py-2.5">
+      <div className="flex items-center gap-2.5 min-w-0">
+        <div className="w-8 h-8 rounded-full bg-gradient-to-tr from-yellow-400 to-purple-600 p-0.5 shrink-0">
+          <div className="w-full h-full rounded-full bg-white p-0.5">
+            <div className="w-full h-full rounded-full bg-gray-200 overflow-hidden flex items-center justify-center text-[10px] font-bold uppercase">
+              {profilePic
+                ? <img src={profilePic} alt="" className="w-full h-full object-cover" referrerPolicy="no-referrer" />
+                : <span>{post.username[0]}</span>}
+            </div>
+          </div>
+        </div>
+        <span className="font-semibold text-sm truncate">{post.username}</span>
+      </div>
+      <MoreHorizontal size={20} className="text-gray-500 shrink-0" />
+    </header>
+
+    {/*
+      Taller ceiling than the modal so ordinary portrait media (9:16 reels,
+      4:5 photos) fills the feed width instead of sitting in side bars, while
+      still stopping anything extreme from swallowing the screen.
+    */}
+    <MediaCarousel post={post} paused={paused} heightCap="max-h-[85vh]" fillWidth className="bg-black" />
+
+    <div className="px-3 pt-3 pb-1 flex items-center justify-between">
+      <div className="flex items-center gap-4">
+        <Heart size={24} className="cursor-pointer" />
+        <MessageCircle size={24} className="cursor-pointer" />
+        <Send size={24} className="cursor-pointer" />
+      </div>
+      <Bookmark size={24} className="cursor-pointer" />
+    </div>
+
+    {post.caption && (
+      <div className="px-3 pb-1 text-sm">
+        <span className="font-semibold mr-2">{post.username}</span>
+        <span className="whitespace-pre-wrap">{post.caption}</span>
+      </div>
+    )}
+
+    <div className="px-3 pb-3 pt-1 text-[10px] uppercase tracking-wide text-gray-400">
+      {formatDateSafe(post.date, 'MMMM d, yyyy')}
+    </div>
+  </article>
+);

src/components/MediaCarousel.tsx

@@ -0,0 +1,112 @@
+import React, { useEffect, useState } from 'react';
+import { ChevronLeft, ChevronRight } from 'lucide-react';
+import { motion, AnimatePresence } from 'motion/react';
+import { Post } from '../types';
+import { cn } from '../lib/utils';
+import { NAVIGATE, prefersReducedMotion, withVelocity } from '../lib/motion';
+import { MediaRenderer } from './MediaRenderer';
+
+interface MediaCarouselProps {
+  post: Post;
+  /** Pause video even when this slide is on screen (feed: only one plays). */
+  paused?: boolean;
+  /** Override the media height ceiling (the feed allows taller media). */
+  heightCap?: string;
+  /** Size video to the container width (see MediaRenderer). */
+  fillWidth?: boolean;
+  className?: string;
+}
+
+/**
+ * The horizontal slide strip for one post.
+ *
+ * Shared by the desktop modal and the mobile feed so a carousel behaves the
+ * same in both. Horizontal drag belongs to the carousel and never navigates
+ * between posts — vertical movement is the page's to handle.
+ */
+export const MediaCarousel: React.FC<MediaCarouselProps> = ({ post, paused, heightCap, fillWidth, className }) => {
+  const [index, setIndex] = useState(0);
+  const [slide, setSlide] = useState<{ dir: number; velocity: number }>({ dir: 0, velocity: 0 });
+  const reduceMotion = prefersReducedMotion();
+
+  useEffect(() => setIndex(0), [post.id]);
+
+  const paginate = (dir: number, velocity = 0) => {
+    const next = index + dir;
+    if (next < 0 || next >= post.media.length) return;
+    setSlide({ dir, velocity });
+    setIndex(next);
+  };
+
+  const variants = {
+    enter: (d: number) => ({ x: d > 0 ? '100%' : '-100%', opacity: 1, zIndex: 0 }),
+    center: { x: 0, opacity: 1, zIndex: 1 },
+    exit: (d: number) => ({ x: d < 0 ? '100%' : '-100%', opacity: 1, zIndex: 0 }),
+  };
+  const swipePower = (offset: number, velocity: number) => Math.abs(offset) * velocity;
+  const current = post.media[index];
+
+  return (
+    <div className={cn('relative bg-black flex items-center justify-center group overflow-hidden w-full', className)}>
+      <div className="w-full grid grid-cols-1 grid-rows-1">
+        <AnimatePresence initial={false} custom={slide.dir}>
+          <motion.div
+            key={`${post.id}-${index}`}
+            custom={slide.dir}
+            variants={variants}
+            initial="enter"
+            animate="center"
+            exit="exit"
+            transition={reduceMotion ? { duration: 0 } : withVelocity(slide.velocity, NAVIGATE)}
+            drag={post.media.length > 1 ? 'x' : false}
+            dragDirectionLock
+            dragConstraints={{ left: 0, right: 0 }}
+            dragElastic={0.5}
+            onDragEnd={(e, { offset, velocity }) => {
+              const power = swipePower(offset.x, velocity.x);
+              if (power < -15000) paginate(1, velocity.x);
+              else if (power > 15000) paginate(-1, velocity.x);
+            }}
+            className="col-start-1 row-start-1 w-full flex items-center justify-center relative touch-pan-y"
+          >
+            {current && <MediaRenderer file={current} isFullView paused={paused} heightCap={heightCap} fillWidth={fillWidth} />}
+          </motion.div>
+        </AnimatePresence>
+      </div>
+
+      {post.media.length > 1 && (
+        <>
+          {index > 0 && (
+            <button
+              aria-label="Previous photo"
+              onClick={(e) => { e.stopPropagation(); paginate(-1); }}
+              className="hidden md:block absolute left-4 top-1/2 -translate-y-1/2 bg-white/20 hover:bg-white/40 text-white p-2 rounded-full backdrop-blur-md transition-all opacity-0 group-hover:opacity-100 z-30"
+            >
+              <ChevronLeft size={24} />
+            </button>
+          )}
+          {index < post.media.length - 1 && (
+            <button
+              aria-label="Next photo"
+              onClick={(e) => { e.stopPropagation(); paginate(1); }}
+              className="hidden md:block absolute right-4 top-1/2 -translate-y-1/2 bg-white/20 hover:bg-white/40 text-white p-2 rounded-full backdrop-blur-md transition-all opacity-0 group-hover:opacity-100 z-30"
+            >
+              <ChevronRight size={24} />
+            </button>
+          )}
+          <div className="absolute bottom-4 left-1/2 -translate-x-1/2 flex gap-1.5 z-30">
+            {post.media.map((_, i) => (
+              <div
+                key={i}
+                className={cn(
+                  'w-1.5 h-1.5 rounded-full transition-all',
+                  i === index ? 'bg-blue-500 scale-125' : 'bg-white/40 shadow-sm',
+                )}
+              />
+            ))}
+          </div>
+        </>
+      )}
+    </div>
+  );
+};

src/components/MediaRenderer.tsx

@@ -0,0 +1,84 @@
+import React, { useState, useEffect, useRef } from 'react';
+import { Play, Volume2, VolumeX } from 'lucide-react';
+import { MediaFile } from '../types';
+import { cn } from '../lib/utils';
+
+interface MediaRendererProps {
+  file: MediaFile;
+  className?: string;
+  isFullView?: boolean;
+  /** Hold playback: the feed keeps every off-screen video paused. */
+  paused?: boolean;
+  /** Cap media height to this instead of the default full-view ceiling. */
+  heightCap?: string;
+  /**
+   * Size video to the container width rather than its own intrinsic size.
+   *
+   * A <video> reports 300x150 until metadata loads, so `w-auto` makes it render
+   * narrow and then jump to full width. The feed needs a stable width more than
+   * it needs a snug fit.
+   */
+  fillWidth?: boolean;
+}
+
+export const MediaRenderer = ({ file, className, isFullView, paused, heightCap, fillWidth }: MediaRendererProps) => {
+  // Try to play with sound: opening the modal is a user gesture, so browsers
+  // generally allow it. If this particular browser still refuses, the effect
+  // below falls back to muted playback rather than leaving a stalled video.
+  const [isMuted, setIsMuted] = useState(false);
+  const videoRef = useRef<HTMLVideoElement>(null);
+
+  useEffect(() => {
+    const video = videoRef.current;
+    if (!video || file.type !== 'video') return;
+
+    if (paused) {
+      video.pause();
+      return;
+    }
+
+    let cancelled = false;
+    video.muted = false;
+    video.play().catch(() => {
+      if (cancelled) return;
+      setIsMuted(true);
+      video.muted = true;
+      video.play().catch(() => { /* user can start it from the controls */ });
+    });
+
+    return () => { cancelled = true; };
+  }, [file.url, file.type, paused]);
+  /**
+   * In full view the media must never outgrow the viewport.
+   *
+   * Video is sized to its own aspect within the cap (`w-auto`) so a portrait
+   * clip doesn't sit in a wide letterbox, while images keep filling the modal
+   * width and only gain a height ceiling — `object-contain` stops the cap from
+   * distorting anything that hits it.
+   *
+   * The desktop cap subtracts the modal's own padding (md:p-10 = 2.5rem each
+   * side); mobile leaves room for the caption panel stacked underneath.
+   */
+  const fullViewCap = `${heightCap ?? 'max-h-[70vh] md:max-h-[calc(100vh-5rem)]'} object-contain`;
+  const videoFullView = fillWidth
+    ? `block w-full h-auto ${fullViewCap}`
+    : `block w-auto max-w-full ${fullViewCap}`;
+  const videoSizing = isFullView ? videoFullView : "w-full h-full object-cover";
+  const imageSizing = isFullView ? `block w-full h-auto ${fullViewCap}` : "w-full h-full object-cover";
+  const sizingClass = file.type === 'video' ? videoSizing : imageSizing;
+  const mediaStyle = { transform: 'translateZ(0)' };
+
+  if (!file.url) return <div className={cn("bg-gray-100 flex items-center justify-center text-black", sizingClass)}><Play size={24} className="text-gray-300" /></div>;
+
+  if (file.type === 'video') {
+    return (
+      <div className="relative w-full h-full flex items-center justify-center group/video text-black">
+        <video ref={videoRef} src={file.url} className={cn("transition-all duration-300", sizingClass, className)} style={mediaStyle} playsInline autoPlay muted={isMuted} loop controls />
+        <button onClick={(e) => { e.stopPropagation(); setIsMuted(!isMuted); }} className="absolute bottom-16 right-4 z-30 bg-black/40 hover:bg-black/60 text-white p-2 rounded-full backdrop-blur-md transition-all md:opacity-0 md:group-hover/video:opacity-100">
+          {isMuted ? <VolumeX size={20} /> : <Volume2 size={20} />}
+        </button>
+      </div>
+    );
+  }
+  return <img src={file.url} alt="" className={cn("transition-all duration-300", sizingClass, className)} style={mediaStyle} referrerPolicy="no-referrer" decoding="async" loading="eager" />;
+};

src/components/PostFeed.tsx

@@ -0,0 +1,150 @@
+import React, { useCallback, useEffect, useLayoutEffect, useMemo, useRef, useState } from 'react';
+import { ChevronLeft } from 'lucide-react';
+import { Post } from '../types';
+import { FeedPost } from './FeedPost';
+
+interface PostFeedProps {
+  posts: Post[];
+  /** Post the feed should open at. */
+  initialPostId: string;
+  profilePic: string | null;
+  onClose: () => void;
+  /** Fires as the post crossing the viewport centre changes. */
+  onActivePostChange: (post: Post) => void;
+  title?: string;
+}
+
+/** Posts added each time the feed grows in either direction. */
+const BATCH = 6;
+/** Render this many ahead of the entry point so the first scroll is smooth. */
+const LOOKAHEAD = 3;
+
+/**
+ * The mobile post view: a real scrolling feed, not a modal.
+ *
+ * Only a window of posts around the entry point is mounted — a profile can hold
+ * thousands, and mounting them all would mean thousands of full-size images.
+ * The window grows in both directions as you scroll; growing *upwards* shifts
+ * everything below it, so the scroll position is corrected in the same frame to
+ * keep the content under your thumb still.
+ */
+export const PostFeed: React.FC<PostFeedProps> = ({
+  posts, initialPostId, profilePic, onClose, onActivePostChange, title,
+}) => {
+  const initialIndex = useMemo(() => {
+    const found = posts.findIndex(p => p.id === initialPostId);
+    return found === -1 ? 0 : found;
+  }, [posts, initialPostId]);
+
+  const [range, setRange] = useState(() => ({
+    start: initialIndex,
+    end: Math.min(posts.length, initialIndex + LOOKAHEAD + 1),
+  }));
+  const [activeId, setActiveId] = useState(initialPostId);
+
+  const scrollRef = useRef<HTMLDivElement>(null);
+  const topSentinelRef = useRef<HTMLDivElement>(null);
+  const bottomSentinelRef = useRef<HTMLDivElement>(null);
+  /** Distance from the bottom of the content, captured before a prepend. */
+  const anchorRef = useRef<number | null>(null);
+
+  const visible = posts.slice(range.start, range.end);
+
+  const extendDown = useCallback(() => {
+    setRange(r => (r.end >= posts.length ? r : { ...r, end: Math.min(posts.length, r.end + BATCH) }));
+  }, [posts.length]);
+
+  const extendUp = useCallback(() => {
+    const el = scrollRef.current;
+    if (!el) return;
+    setRange(r => {
+      if (r.start === 0) return r;
+      // Measure from the bottom: prepending changes scrollHeight, but the
+      // distance between our position and the end of the content does not.
+      anchorRef.current = el.scrollHeight - el.scrollTop;
+      return { ...r, start: Math.max(0, r.start - BATCH) };
+    });
+  }, []);
+
+  // Restore the scroll position in the same frame the prepended posts appear,
+  // before the browser paints, so nothing visibly jumps.
+  useLayoutEffect(() => {
+    const el = scrollRef.current;
+    if (el && anchorRef.current !== null) {
+      el.scrollTop = el.scrollHeight - anchorRef.current;
+      anchorRef.current = null;
+    }
+  }, [range.start]);
+
+  // Grow the window when either end comes into view.
+  useEffect(() => {
+    const root = scrollRef.current;
+    if (!root) return;
+    const observer = new IntersectionObserver(entries => {
+      for (const entry of entries) {
+        if (!entry.isIntersecting) continue;
+        if (entry.target === bottomSentinelRef.current) extendDown();
+        if (entry.target === topSentinelRef.current) extendUp();
+      }
+    }, { root, rootMargin: '600px 0px' });
+
+    if (topSentinelRef.current) observer.observe(topSentinelRef.current);
+    if (bottomSentinelRef.current) observer.observe(bottomSentinelRef.current);
+    return () => observer.disconnect();
+  }, [extendDown, extendUp]);
+
+  // Track the post crossing the viewport centre. The negative margins collapse
+  // the root to a thin band, so exactly one post qualifies at a time.
+  useEffect(() => {
+    const root = scrollRef.current;
+    if (!root) return;
+    const observer = new IntersectionObserver(entries => {
+      for (const entry of entries) {
+        if (!entry.isIntersecting) continue;
+        const id = (entry.target as HTMLElement).dataset.postId;
+        if (id) setActiveId(id);
+      }
+    }, { root, rootMargin: '-45% 0px -45% 0px', threshold: 0 });
+
+    root.querySelectorAll('[data-post-id]').forEach(el => observer.observe(el));
+    return () => observer.disconnect();
+  }, [visible.length, range.start]);
+
+  useEffect(() => {
+    const post = posts.find(p => p.id === activeId);
+    if (post) onActivePostChange(post);
+  }, [activeId, posts, onActivePostChange]);
+
+  // Escape closes, matching the modal it replaces.
+  useEffect(() => {
+    const onKey = (e: KeyboardEvent) => { if (e.key === 'Escape') onClose(); };
+    window.addEventListener('keydown', onKey);
+    return () => window.removeEventListener('keydown', onKey);
+  }, [onClose]);
+
+  return (
+    <div className="fixed inset-0 z-50 bg-white flex flex-col">
+      <header className="flex items-center gap-3 px-2 h-12 border-b border-gray-200 bg-white/95 backdrop-blur-md shrink-0">
+        <button onClick={onClose} aria-label="Back" className="p-2 -ml-1 active:opacity-60">
+          <ChevronLeft size={24} />
+        </button>
+        <span className="font-semibold text-base">{title ?? 'Posts'}</span>
+      </header>
+
+      <div ref={scrollRef} className="flex-1 overflow-y-auto overscroll-contain">
+        <div ref={topSentinelRef} aria-hidden />
+        {visible.map(post => (
+          <div key={post.id} data-post-id={post.id}>
+            <FeedPost post={post} profilePic={profilePic} paused={post.id !== activeId} />
+          </div>
+        ))}
+        <div ref={bottomSentinelRef} aria-hidden />
+        {range.end >= posts.length && (
+          <div className="py-10 text-center text-xs uppercase tracking-widest text-gray-400">
+            End of {title?.toLowerCase() ?? 'posts'}
+          </div>
+        )}
+      </div>
+    </div>
+  );
+};

src/components/PostModal.tsx

@@ -0,0 +1,219 @@
+import React, { useState, useEffect } from 'react';
+import { 
+  ChevronLeft, 
+  ChevronRight, 
+  X, 
+  MoreHorizontal, 
+  Heart, 
+  MessageCircle, 
+  Play, 
+  Bookmark 
+} from 'lucide-react';
+import { motion, AnimatePresence } from 'motion/react';
+import { Post } from '../types';
+import { cn, formatDateSafe } from '../lib/utils';
+import { FADE, NAVIGATE, PRESENT, prefersReducedMotion, withVelocity } from '../lib/motion';
+import { MediaRenderer } from './MediaRenderer';
+
+interface PostModalProps {
+  post: Post;
+  nextPost?: Post;
+  prevPost?: Post;
+  onClose: () => void;
+  onNextPost?: () => void;
+  onPrevPost?: () => void;
+  hasNextPost?: boolean;
+  hasPrevPost?: boolean;
+  profilePic: string | null;
+}
+
+export const PostModal: React.FC<PostModalProps> = ({ 
+  post, nextPost, prevPost, onClose, onNextPost, onPrevPost, hasNextPost, hasPrevPost, profilePic
+}) => {
+  const [currentIndex, setCurrentIndex] = useState(0);
+  /**
+   * How the next slide/post should enter: along which axis, in which direction,
+   * and carrying how much velocity from the gesture that triggered it.
+   */
+  const [slideMotion, setSlideMotion] = useState<{ axis: 'x' | 'y'; dir: number; velocity: number }>(
+    { axis: 'x', dir: 0, velocity: 0 },
+  );
+  const reduceMotion = prefersReducedMotion();
+
+  // Preloading Logic
+  useEffect(() => {
+    const controller = new AbortController();
+    
+    const preloadMedia = async (url: string, type: 'image' | 'video') => {
+      if (!url) return;
+      try {
+        if (type === 'image') {
+          const img = new Image();
+          img.src = url;
+        } else {
+          const video = document.createElement('video');
+          video.src = url;
+          video.preload = 'auto';
+        }
+      } catch (e) {}
+    };
+
+    // 1. Current post: Immediate preload of first two slides
+    if (post.media[0]) preloadMedia(post.media[0].url, post.media[0].type);
+    if (post.media[1]) preloadMedia(post.media[1].url, post.media[1].type);
+
+    // 2. Next/Prev posts: Preload their first slides
+    if (nextPost?.media[0]) preloadMedia(nextPost.media[0].url, nextPost.media[0].type);
+    if (prevPost?.media[0]) preloadMedia(prevPost.media[0].url, prevPost.media[0].type);
+
+    // 3. Current post: Delayed preload of the rest
+    const timeout = setTimeout(() => {
+      for (let i = 2; i < post.media.length; i++) {
+        if (controller.signal.aborted) break;
+        preloadMedia(post.media[i].url, post.media[i].type);
+      }
+    }, 1000);
+
+    return () => {
+      controller.abort();
+      clearTimeout(timeout);
+    };
+  }, [post.id, post.media, nextPost?.id, prevPost?.id]);
+
+  useEffect(() => setCurrentIndex(0), [post.id]);
+  useEffect(() => {
+    // Arrows page within the carousel — the thing the arrows visually point at.
+    // Moving between posts stays on the side buttons, with , and . as keyboard
+    // equivalents.
+    const handleKeyDown = (e: KeyboardEvent) => {
+      if (e.key === 'ArrowRight') paginate(1);
+      else if (e.key === 'ArrowLeft') paginate(-1);
+      else if (e.key === '.') goToPost(1, 'x');
+      else if (e.key === ',') goToPost(-1, 'x');
+      else if (e.key === 'Escape') onClose();
+    };
+    window.addEventListener('keydown', handleKeyDown);
+    return () => window.removeEventListener('keydown', handleKeyDown);
+  }, [onNextPost, onPrevPost, currentIndex, post.media.length, onClose]);
+
+  const paginate = (newDirection: number, velocity = 0) => {
+    const nextIndex = currentIndex + newDirection;
+    if (nextIndex >= 0 && nextIndex < post.media.length) {
+      setSlideMotion({ axis: 'x', dir: newDirection, velocity });
+      setCurrentIndex(nextIndex);
+    }
+  };
+
+  /**
+   * Move between posts, animating along the axis the input implies: vertical
+   * for a touch swipe, horizontal for the desktop arrows and arrow keys.
+   */
+  const goToPost = (dir: 1 | -1, axis: 'x' | 'y', velocity = 0) => {
+    if (dir > 0 ? !hasNextPost : !hasPrevPost) return;
+    setSlideMotion({ axis, dir, velocity });
+    if (dir > 0) onNextPost?.(); else onPrevPost?.();
+  };
+
+  type SlideMotion = { axis: 'x' | 'y'; dir: number };
+  const offscreen = (dir: number) => (dir > 0 ? '100%' : '-100%');
+  const variants = {
+    enter: ({ axis, dir }: SlideMotion) =>
+      axis === 'y'
+        ? { y: offscreen(dir), x: 0, opacity: 1, zIndex: 0 }
+        : { x: offscreen(dir), y: 0, opacity: 1, zIndex: 0 },
+    center: { zIndex: 1, x: 0, y: 0, opacity: 1 },
+    exit: ({ axis, dir }: SlideMotion) =>
+      axis === 'y'
+        ? { zIndex: 0, y: offscreen(-dir), x: 0, opacity: 1 }
+        : { zIndex: 0, x: offscreen(-dir), y: 0, opacity: 1 },
+  };
+  const swipePower = (offset: number, velocity: number) => Math.abs(offset) * velocity;
+
+  /**
+   * Desktop-only surface: mobile opens PostFeed instead, so the only vertical
+   * gesture left here is drag-to-dismiss.
+   */
+  const handleVerticalDragEnd = (offset: { y: number }, velocity: { y: number }) => {
+    if (offset.y > 200 || velocity.y > 800) onClose();
+  };
+
+  /*
+   * Horizontal padding on the overlay reserves a gutter for the prev/next
+   * arrows so they always sit *outside* the modal. Without it the modal grows
+   * until it sits under them and a white chevron lands on the white caption
+   * panel, leaving the control invisible until hovered.
+   *
+   * overscroll-contain stops wheel events chaining through to the very long
+   * post grid behind the overlay.
+   */
+  return (
+    <motion.div initial={{ opacity: 0 }} animate={{ opacity: 1 }} exit={{ opacity: 0 }} transition={FADE} className="fixed inset-0 z-50 flex items-start justify-center bg-[#0c1014]/95 md:bg-[#0c1014]/70 p-0 md:py-10 md:px-16 lg:px-24 overflow-y-auto overscroll-contain text-black" onClick={onClose}>
+      <div className="min-h-full w-full flex items-center justify-center md:py-0">
+        <button onClick={onClose} className="fixed top-4 right-4 text-white hover:text-gray-300 z-50 p-2 md:p-3 bg-black/20 rounded-full backdrop-blur-sm"><X size={24} className="md:w-8 md:h-8" /></button>
+        {/* Solid pill so the arrows read against whatever sits behind them. */}
+        {hasPrevPost && onPrevPost && <button aria-label="Previous post" onClick={(e) => { e.stopPropagation(); goToPost(-1, 'x'); }} className="hidden md:flex items-center justify-center fixed md:left-3 lg:left-6 top-1/2 -translate-y-1/2 z-50 p-2 rounded-full bg-white/90 hover:bg-white text-gray-800 shadow-lg transition-transform hover:scale-110 active:scale-90"><ChevronLeft size={28} strokeWidth={2} /></button>}
+        {hasNextPost && onNextPost && <button aria-label="Next post" onClick={(e) => { e.stopPropagation(); goToPost(1, 'x'); }} className="hidden md:flex items-center justify-center fixed md:right-3 lg:right-6 top-1/2 -translate-y-1/2 z-50 p-2 rounded-full bg-white/90 hover:bg-white text-gray-800 shadow-lg transition-transform hover:scale-110 active:scale-90"><ChevronRight size={28} strokeWidth={2} /></button>}
+        <motion.div drag="y" dragDirectionLock dragConstraints={{ top: 0, bottom: 0 }} dragElastic={0.15} onDragEnd={(e, { offset, velocity }) => handleVerticalDragEnd(offset, velocity)} initial={reduceMotion ? false : { opacity: 0, scale: 0.96 }} animate={{ opacity: 1, scale: 1 }} exit={reduceMotion ? { opacity: 0 } : { opacity: 0, scale: 0.96 }} transition={PRESENT} className="bg-black flex flex-col md:flex-row w-full max-w-6xl h-auto md:rounded-sm overflow-hidden shadow-2xl relative text-black" onClick={e => e.stopPropagation()}>
+          <div className="relative bg-black flex items-center justify-center group overflow-hidden w-full h-auto text-black">
+            <div className="w-full grid grid-cols-1 grid-rows-1 text-black">
+              <AnimatePresence initial={false} custom={slideMotion}>
+                <motion.div
+                  key={`${post.id}-${currentIndex}`}
+                  custom={slideMotion}
+                  variants={variants}
+                  initial="enter"
+                  animate="center"
+                  exit="exit"
+                  transition={reduceMotion
+                    ? { duration: 0 }
+                    : { x: withVelocity(slideMotion.velocity, NAVIGATE), y: withVelocity(slideMotion.velocity, NAVIGATE) }}
+                  
+                  drag="x" 
+                  dragDirectionLock 
+                  dragConstraints={{ left: 0, right: 0 }} 
+                  dragElastic={0.5} 
+                  onDragEnd={(e, { offset, velocity }) => {
+                    // Carousel only. Crossing into the next post from the last
+                    // slide made a horizontal flick mean two different things.
+                    const s = swipePower(offset.x, velocity.x);
+                    if (s < -15000) paginate(1, velocity.x);
+                    else if (s > 15000) paginate(-1, velocity.x);
+                  }} 
+                  className="col-start-1 row-start-1 w-full flex items-center justify-center cursor-grab active:cursor-grabbing relative text-black"
+                >
+                  <MediaRenderer file={post.media[currentIndex]} isFullView={true} />
+                </motion.div>
+              </AnimatePresence>
+            </div>
+            {post.media.length > 1 && (
+              <>
+                {currentIndex > 0 && <button onClick={(e) => { e.stopPropagation(); paginate(-1); }} className="hidden md:block absolute left-4 top-1/2 -translate-y-1/2 bg-white/20 hover:bg-white/40 text-white p-2 rounded-full backdrop-blur-md transition-all opacity-0 group-hover:opacity-100 z-30"><ChevronLeft size={24} /></button>}
+                {currentIndex < post.media.length - 1 && <button onClick={(e) => { e.stopPropagation(); paginate(1); }} className="hidden md:block absolute right-4 top-1/2 -translate-y-1/2 bg-white/20 hover:bg-white/40 text-white p-2 rounded-full backdrop-blur-md transition-all opacity-0 group-hover:opacity-100 z-30"><ChevronRight size={24} /></button>}
+                <div className="absolute bottom-4 left-1/2 -translate-x-1/2 flex gap-1.5 z-30 text-black">{post.media.map((_, i) => <div key={i} className={cn("w-1.5 h-1.5 rounded-full transition-all", i === currentIndex ? "bg-blue-500 scale-125" : "bg-white/40 shadow-sm")} />)}</div>
+              </>
+            )}
+          </div>
+          <div className="w-full md:w-80 lg:w-96 bg-white flex flex-col border-l border-gray-200 overflow-hidden shrink-0 text-black">
+            <div className="p-3 md:p-4 border-b border-gray-100 flex items-center justify-between shrink-0 text-black">
+              <div className="flex items-center gap-3 text-black">
+                <div className="w-8 h-8 rounded-full bg-gradient-to-tr from-yellow-400 to-purple-600 p-0.5 text-black"><div className="w-full h-full rounded-full bg-white p-0.5 text-black"><div className="w-full h-full rounded-full bg-gray-200 flex items-center justify-center overflow-hidden text-[10px] font-bold uppercase text-black">{profilePic ? <img src={profilePic} alt="" className="w-full h-full object-cover text-black" referrerPolicy="no-referrer" /> : <span className="text-black">{post.username[0]}</span>}</div></div></div>
+                <span className="font-semibold text-sm text-black">{post.username}</span>
+              </div>
+              <MoreHorizontal size={20} className="text-gray-500 text-black" />
+            </div>
+            <div className="flex-1 overflow-y-auto p-3 md:p-4 space-y-4 min-h-0 md:max-h-[60vh] text-black">
+              <div className="flex gap-3 text-black">
+                <div className="w-8 h-8 rounded-full bg-gray-200 flex-shrink-0 flex items-center justify-center text-[10px] font-bold uppercase overflow-hidden text-black">{profilePic ? <img src={profilePic} alt="" className="w-full h-full object-cover" referrerPolicy="no-referrer" /> : <span className="text-black">{post.username[0]}</span>}</div>
+                <div className="text-sm text-black"><span className="font-semibold mr-2 text-black">{post.username}</span><span className="whitespace-pre-wrap text-black">{post.caption}</span><div className="mt-2 text-xs text-gray-500 uppercase tracking-tight text-black">{formatDateSafe(post.date, 'MMMM d, yyyy')}</div></div>
+              </div>
+            </div>
+            <div className="p-3 md:p-4 border-t border-gray-100 space-y-3 shrink-0 bg-white text-black">
+              <div className="flex items-center justify-between text-black"><div className="flex items-center gap-4 text-black"><Heart size={24} className="hover:text-gray-500 cursor-pointer text-black" /><MessageCircle size={24} className="hover:text-gray-500 cursor-pointer text-black" /><Play size={24} className="hover:text-gray-500 cursor-pointer text-black" /></div><Bookmark size={24} className="hover:text-gray-500 cursor-pointer text-black" /></div>
+              <div className="text-sm flex items-center gap-2 text-black"><span className="font-semibold text-black">Archived Post</span><span className="text-gray-400 font-normal text-xs text-black">{post.id}</span></div>
+            </div>
+          </div>
+        </motion.div>
+      </div>
+    </motion.div>
+  );
+};

src/components/PostThumbnail.tsx

@@ -0,0 +1,124 @@
+import React, { useState, useEffect, useRef } from 'react';
+import { Play, Image as ImageIcon } from 'lucide-react';
+import { cn } from '../lib/utils';
+import { Post } from '../types';
+
+interface PostThumbnailProps {
+  post: Post;
+  className?: string;
+  thumbnailUrl?: string; // High-res thumbnail from queue
+  onRequestThumbnail: (id: string, url: string) => void;
+}
+
+const videoThumbnailCache = new Map<string, string>();
+
+export const PostThumbnail = ({ post, className, thumbnailUrl, onRequestThumbnail }: PostThumbnailProps) => {
+  const [videoThumbnail, setVideoThumbnail] = useState<string | null>(videoThumbnailCache.get(post.media[0].url) || null);
+  const [isInView, setIsInView] = useState(false);
+  const containerRef = useRef<HTMLDivElement>(null);
+
+  const mainMedia = post.media[0];
+  const isVideo = mainMedia.type === 'video';
+
+  useEffect(() => {
+    const observer = new IntersectionObserver(([entry]) => {
+      if (entry.isIntersecting) { 
+        setIsInView(true); 
+        observer.disconnect(); 
+      }
+    }, { rootMargin: '400px' }); // Larger margin for smoother scrolling
+    
+    if (containerRef.current) {
+      observer.observe(containerRef.current);
+    }
+    return () => observer.disconnect();
+  }, []);
+
+  useEffect(() => {
+    if (!isInView) return;
+
+    if (isVideo) {
+      if (videoThumbnail) return;
+      const video = document.createElement('video');
+      video.src = `${mainMedia.url}#t=0.1`; 
+      video.preload = 'metadata'; 
+      video.muted = true; 
+      video.playsInline = true;
+      
+      const captureFrame = () => {
+        try {
+          const canvas = document.createElement('canvas');
+          canvas.width = video.videoWidth; canvas.height = video.videoHeight;
+          const ctx = canvas.getContext('2d');
+          if (ctx && video.videoWidth > 0) {
+            ctx.drawImage(video, 0, 0, canvas.width, canvas.height);
+            const dataUrl = canvas.toDataURL('image/jpeg', 0.6);
+            videoThumbnailCache.set(mainMedia.url, dataUrl); 
+            setVideoThumbnail(dataUrl);
+          }
+        } catch (err) {} finally { cleanup(); }
+      };
+      
+      const handleLoadedMetadata = () => video.currentTime = 0.1;
+      const handleSeeked = () => captureFrame();
+      const cleanup = () => {
+        video.removeEventListener('loadedmetadata', handleLoadedMetadata);
+        video.removeEventListener('seeked', handleSeeked);
+        video.removeAttribute('src'); 
+        video.load();
+      };
+
+      video.addEventListener('loadedmetadata', handleLoadedMetadata);
+      video.addEventListener('seeked', handleSeeked);
+      video.addEventListener('error', cleanup);
+      const timeout = setTimeout(() => cleanup(), 5000);
+      return () => { clearTimeout(timeout); cleanup(); };
+    } else {
+      // Request high-res image thumbnailing only if size > 1MiB
+      const ONE_MIB = 1024 * 1024;
+      if (mainMedia.size && mainMedia.size > ONE_MIB) {
+        onRequestThumbnail(post.id, mainMedia.url);
+      }
+    }
+  }, [isInView, isVideo, mainMedia.url, mainMedia.size, post.id, onRequestThumbnail, videoThumbnail]);
+
+  // Determine if we are actually expecting a high-res thumbnail
+  const ONE_MIB = 1024 * 1024;
+  const isHighRes = !isVideo && mainMedia.size && mainMedia.size > ONE_MIB;
+  const isGenerating = isHighRes && !thumbnailUrl;
+
+  // Use high-res thumbnail if available, then video thumb, then original
+  const displayUrl = thumbnailUrl || videoThumbnail || post.thumbnail;
+
+  if (!displayUrl && isVideo) {
+    return (
+      <div ref={containerRef} className={cn("w-full h-full bg-gray-100 flex items-center justify-center text-black", className)}>
+        <Play size={20} className="text-gray-300" fill="currentColor" />
+      </div>
+    );
+  }
+
+  if (!displayUrl) {
+    return (
+      <div ref={containerRef} className={cn("w-full h-full bg-gray-50 flex items-center justify-center text-black", className)}>
+        <ImageIcon size={20} className="text-gray-200" />
+      </div>
+    );
+  }
+
+  return (
+    <div ref={containerRef} className="w-full h-full">
+      <img 
+        src={displayUrl} 
+        alt="" 
+        className={cn(
+          "w-full h-full object-cover transition-all duration-700", 
+          className, 
+          isGenerating ? "blur-sm scale-105" : "blur-0 scale-100"
+        )} 
+        referrerPolicy="no-referrer"
+        loading="lazy"
+      />
+    </div>
+  );
+};

src/components/StoryViewer.tsx

@@ -0,0 +1,236 @@
+import React, { useState, useEffect, useRef } from 'react';
+import { 
+  ChevronLeft, 
+  ChevronRight, 
+  Volume2, 
+  VolumeX, 
+  X 
+} from 'lucide-react';
+import { motion } from 'motion/react';
+import { Post } from '../types';
+import { cn, formatDateSafe } from '../lib/utils';
+import { FADE, PRESENT, prefersReducedMotion } from '../lib/motion';
+
+interface StoryViewerProps {
+  stories: Post[];
+  onClose: () => void;
+  profilePic: string | null;
+  /** Highlight name, shown in place of the date when viewing a highlight. */
+  title?: string;
+}
+
+export const StoryViewer: React.FC<StoryViewerProps> = ({
+  stories,
+  onClose,
+  profilePic,
+  title
+}) => {
+  const [currentStoryIndex, setCurrentStoryIndex] = useState(0);
+  const [progress, setProgress] = useState(0);
+  // Opening the reel is a user gesture, so try for sound; the effect below
+  // falls back to muted if the browser refuses, which would otherwise stall
+  // the progress bar on the first video.
+  const [isMuted, setIsMuted] = useState(false);
+  const videoRef = useRef<HTMLVideoElement>(null);
+  const reduceMotion = prefersReducedMotion();
+  const story = stories[currentStoryIndex];
+  const primary = story?.media?.[0];
+
+  useEffect(() => {
+    setProgress(0);
+    let duration = 5000;
+    const interval = 50;
+
+    const updateProgress = () => {
+      if (primary?.type === 'video' && videoRef.current) {
+        const currentTime = videoRef.current.currentTime;
+        const totalTime = videoRef.current.duration;
+        if (totalTime) {
+          setProgress((currentTime / totalTime) * 100);
+        }
+      } else {
+        setProgress(prev => {
+          const step = (interval / duration) * 100;
+          if (prev >= 100) return 100;
+          return prev + step;
+        });
+      }
+    };
+
+    const timer = setInterval(() => {
+      updateProgress();
+    }, interval);
+
+    return () => clearInterval(timer);
+  }, [currentStoryIndex, primary]);
+
+  useEffect(() => {
+    const video = videoRef.current;
+    if (!video || primary?.type !== 'video') return;
+
+    let cancelled = false;
+    video.muted = false;
+    video.play().catch(() => {
+      if (cancelled) return;
+      setIsMuted(true);
+      video.muted = true;
+      video.play().catch(() => { /* leave it to the controls */ });
+    });
+
+    return () => { cancelled = true; };
+  }, [primary]);
+
+  useEffect(() => {
+    if (progress >= 100) {
+      if (currentStoryIndex < stories.length - 1) {
+        setCurrentStoryIndex(prev => prev + 1);
+      } else {
+        onClose();
+      }
+    }
+  }, [progress, currentStoryIndex, stories.length, onClose]);
+
+  const nextStory = () => {
+    if (currentStoryIndex < stories.length - 1) {
+      setCurrentStoryIndex(prev => prev + 1);
+    } else {
+      onClose();
+    }
+  };
+
+  const prevStory = () => {
+    if (currentStoryIndex > 0) {
+      setCurrentStoryIndex(prev => prev - 1);
+    }
+  };
+
+  // An empty or exhausted reel has nothing to show; bail before dereferencing.
+  if (!story || !primary) return null;
+
+  return (
+    <motion.div
+      initial={{ opacity: 0 }}
+      animate={{ opacity: 1 }}
+      exit={{ opacity: 0 }}
+      transition={FADE}
+      className="fixed inset-0 z-[100] bg-[#1a1a1a] flex items-center justify-center overflow-hidden text-white"
+      onClick={onClose}
+    >
+      <div className="absolute inset-0 z-0 text-white">
+        <img 
+          src={primary.url}
+          alt=""
+          className="w-full h-full object-cover blur-3xl opacity-30"
+        />
+      </div>
+
+      <button 
+        onClick={(e) => { e.stopPropagation(); prevStory(); }}
+        className={cn(
+          "hidden md:flex absolute left-4 lg:left-20 z-50 text-white/80 hover:text-white transition-all bg-white/10 p-3 rounded-full backdrop-blur-md",
+          currentStoryIndex === 0 && "opacity-0 pointer-events-none"
+        )}
+      >
+        <ChevronLeft size={32} strokeWidth={1.5} />
+      </button>
+
+      <button 
+        onClick={(e) => { e.stopPropagation(); nextStory(); }}
+        className="hidden md:flex absolute right-4 lg:right-20 z-50 text-white/80 hover:text-white transition-all bg-white/10 p-3 rounded-full backdrop-blur-md"
+      >
+        <ChevronRight size={32} strokeWidth={1.5} />
+      </button>
+
+      <motion.div
+        initial={reduceMotion ? false : { scale: 0.94, opacity: 0 }}
+        animate={{ scale: 1, opacity: 1 }}
+        exit={reduceMotion ? { opacity: 0 } : { scale: 0.94, opacity: 0 }}
+        transition={PRESENT}
+        className="relative w-full h-full md:h-[90vh] md:max-w-[45vh] bg-black overflow-hidden md:rounded-lg shadow-2xl z-10 text-white"
+        onClick={e => e.stopPropagation()}
+      >
+        <div 
+          className="absolute top-2 left-2 right-2 z-50 flex px-1 text-white"
+          style={{ gap: stories.length > 100 ? '1px' : (stories.length > 50 ? '2px' : '4px') }}
+        >
+          {stories.map((_, i) => (
+            <div key={i} className="h-1 flex-1 bg-white/20 rounded-full overflow-hidden text-white">
+              <div 
+                className="h-full bg-white transition-all duration-75 text-white"
+                style={{ 
+                  width: i < currentStoryIndex ? '100%' : (i === currentStoryIndex ? `${progress}%` : '0%') 
+                }}
+              />
+            </div>
+          ))}
+        </div>
+
+        <div className="absolute top-6 left-4 right-4 z-50 flex items-center justify-between text-white">
+          <div className="flex items-center gap-2">
+            <div className="w-8 h-8 rounded-full bg-white/10 p-0.5">
+              <div className="w-full h-full rounded-full bg-gray-200 flex items-center justify-center overflow-hidden">
+                {profilePic ? (
+                  <img src={profilePic} alt="" className="w-full h-full object-cover text-black" referrerPolicy="no-referrer" />
+                ) : (
+                  <span className="text-[10px] font-bold text-black uppercase">{story.username[0]}</span>
+                )}
+              </div>
+            </div>
+            <div className="flex items-center gap-2 text-white">
+              <span className="text-xs font-semibold">{story.username}</span>
+              {title && <span className="text-[10px] opacity-80 font-medium truncate max-w-[120px]">{title}</span>}
+              <span className="text-[10px] opacity-60 font-medium">{formatDateSafe(story.date, 'MMM d')}</span>
+            </div>
+          </div>
+          
+          <div className="flex items-center gap-1 text-white">
+            {primary.type === 'video' && (
+              <button 
+                onClick={(e) => { e.stopPropagation(); setIsMuted(!isMuted); }}
+                className="p-2 hover:bg-white/10 rounded-full transition-colors text-white"
+              >
+                {isMuted ? <VolumeX size={20} /> : <Volume2 size={20} />}
+              </button>
+            )}
+            <button onClick={onClose} className="p-2 hover:bg-white/10 rounded-full transition-colors text-white">
+              <X size={24} />
+            </button>
+          </div>
+        </div>
+
+        <div className="w-full h-full flex items-center justify-center pointer-events-none text-white">
+          {primary.type === 'video' ? (
+            <video 
+              ref={videoRef}
+              src={primary.url}
+              className="w-full h-full object-contain"
+              autoPlay 
+              muted={isMuted}
+              playsInline
+              controls
+              onEnded={nextStory}
+            />
+          ) : (
+            <img 
+              src={primary.url}
+              alt=""
+              className="w-full h-full object-contain"
+              referrerPolicy="no-referrer"
+            />
+          )}
+        </div>
+
+        <div className="absolute inset-0 z-20 flex">
+          <div className="w-1/4 h-full cursor-pointer" onClick={prevStory} title="Previous Story" />
+          <div className="w-3/4 h-full cursor-pointer" onClick={nextStory} title="Next Story" />
+        </div>
+
+        {story.caption && (
+          <div className="absolute bottom-16 left-4 right-4 z-50 bg-black/20 backdrop-blur-sm p-3 rounded-lg text-white text-xs text-center border border-white/10">
+            {story.caption}
+          </div>
+        )}
+      </motion.div>
+    </motion.div>
+  );
+};

src/hooks/useArchiveScanner.ts

@@ -0,0 +1,523 @@
+import { useState, useCallback, useRef, useEffect } from 'react';
+// @ts-ignore
+import { XzReadableStream } from 'xz-decompress';
+import { ArchiveFile, CacheData, Post, ServerArchive } from '../types';
+import { setCachedArchive, getDirectoryHandle } from '../lib/archive-cache';
+import { parseArchiveFilename, scopedPostId, EXPORT_RE, INSTALOADER_RE } from '../lib/archive-patterns';
+import { isGalleryDlSidecar, sidecarDate, sidecarIsReel } from '../lib/gallery-dl-sidecar';
+import { DateSource, shouldReplaceDate } from '../lib/post-dates';
+
+const hasDirectoryHandle = async (name: string) => Boolean(await getDirectoryHandle(name));
+
+export const useArchiveScanner = (
+  detectedUsername: string,
+  currentArchive: ServerArchive | null,
+  refreshCachedArchives: () => Promise<void>
+) => {
+  const [isScanning, setIsScanning] = useState(false);
+  const [scanningPhase, setScanningPhase] = useState<'Indexing' | 'Parsing' | 'Checking Cache' | ''>('');
+  const [scannedCount, setScannedCount] = useState(0);
+  const [totalFiles, setTotalFiles] = useState(0);
+  const [scannedFilesLog, setScannedFilesLog] = useState<string[]>([]);
+  const [currentScanningImage, setCurrentScanningImage] = useState<string | null>(null);
+
+  // Result state
+  const [allPosts, setAllPosts] = useState<Post[]>([]);
+  const [allStories, setAllStories] = useState<Post[]>([]);
+  const [allHighlights, setAllHighlights] = useState<Post[]>([]);
+  const [profileMetadata, setProfileMetadata] = useState<{
+    username: string;
+    fullName: string;
+    bio: string;
+    followerCount: number;
+    followingCount: number;
+    externalUrl: string;
+    profilePic: string | null;
+    allProfilePics: string[];
+  }>({
+    username: '',
+    fullName: '',
+    bio: '',
+    followerCount: 0,
+    followingCount: 0,
+    externalUrl: '',
+    profilePic: null,
+    allProfilePics: [],
+  });
+
+  /**
+   * Blob URLs minted for the archive currently in state. They stay alive as long
+   * as that archive is on screen and are released when it is torn down —
+   * otherwise every archive ever opened stays resident for the tab's lifetime.
+   */
+  const createdUrlsRef = useRef<string[]>([]);
+
+  const revokeCreatedUrls = useCallback(() => {
+    for (const url of createdUrlsRef.current) {
+      try { URL.revokeObjectURL(url); } catch { /* already gone */ }
+    }
+    createdUrlsRef.current = [];
+  }, []);
+
+  // Release the last archive's URLs when the app unmounts.
+  useEffect(() => revokeCreatedUrls, [revokeCreatedUrls]);
+
+  /** Hand ownership of an externally-minted blob URL to the scanner's cleanup. */
+  const registerUrl = useCallback((url: string) => {
+    createdUrlsRef.current.push(url);
+  }, []);
+
+  const resetScannerState = useCallback(() => {
+    revokeCreatedUrls();
+    setAllPosts([]);
+    setAllStories([]);
+    setAllHighlights([]);
+    setProfileMetadata({
+      username: '',
+      fullName: '',
+      bio: '',
+      followerCount: 0,
+      followingCount: 0,
+      externalUrl: '',
+      profilePic: null,
+      allProfilePics: [],
+    });
+  }, [revokeCreatedUrls]);
+
+  const handleFiles = useCallback(async (files: ArchiveFile[], archiveContext?: ServerArchive) => {
+    if (!files || files.length === 0) return;
+    setIsScanning(true);
+    resetScannerState();
+    setScanningPhase('Indexing');
+    setScannedCount(0);
+    setTotalFiles(files.length);
+    setScannedFilesLog([]);
+    
+    console.log(`[Scanner] Starting scan of ${files.length} files...`);
+    await new Promise(resolve => setTimeout(resolve, 100));
+
+    /**
+     * Mint a URL for a media file, remembering it if it needs revoking later.
+     * Synchronous and allocation-free: no file contents are read here.
+     */
+    const mintUrl = (file: ArchiveFile, mimeHint?: string) => {
+      const url = file.createObjectUrl(mimeHint);
+      if (file.revocable) createdUrlsRef.current.push(url);
+      return url;
+    };
+
+    /** Stable identity for a media file, used to rehydrate URLs after a reload. */
+    const mediaPath = (file: ArchiveFile) => file.webkitRelativePath || file.name;
+
+    /**
+     * Decompress an `.xz` metadata sidecar.
+     *
+     * Read fully into memory first rather than handing the live HTTP body to
+     * the decompressor. These sidecars are a few KB, so buffering costs
+     * nothing, and streaming was actively harmful: the decompressor stops
+     * reading at the end of the xz member, leaving the response body neither
+     * drained nor cancelled. Across a couple of hundred sidecars that exhausts
+     * the connection pool and every later fetch fails with "Failed to fetch" —
+     * which silently cost Instaloader archives their captions, story flags and
+     * profile metadata, since all of it lives in these files.
+     */
+    const parseXZFile = async (file: ArchiveFile) => {
+      try {
+        const compressed = await file.arrayBuffer();
+        const stream = new XzReadableStream(new Blob([compressed]).stream());
+        return await new Response(stream).json();
+      } catch (e) { console.error(`[Scanner] XZ Parse Error:`, file.name, e); return null; }
+    };
+
+    let lastImageUpdateTime = 0;
+    const throttledSetScanningImage = (url: string) => {
+      const now = Date.now();
+      if (now - lastImageUpdateTime > 1000) {
+        setCurrentScanningImage(url);
+        lastImageUpdateTime = now;
+      }
+    };
+
+    const isImage = (name: string) => /\.(jpg|jpeg|png|webp|gif|bmp|svg|tiff)$/i.test(name);
+    const isVideo = (name: string) => /\.(mp4|webm|ogv|mov)$/i.test(name);
+    const isMedia = (name: string) => isImage(name) || isVideo(name);
+
+    try {
+      const postsMap = new Map<string, Partial<Post>>();
+      /**
+       * Which source supplied each post's date, so a better one can replace it.
+       * Sidecar beats filename beats mtime — see src/lib/post-dates.ts.
+       */
+      const dateSources = new Map<string, DateSource>();
+      const applyDate = (postId: string, post: Partial<Post>, date: string, source: DateSource) => {
+        const current = post.date ? { date: post.date, source: dateSources.get(postId) ?? 'mtime' } : undefined;
+        if (!shouldReplaceDate(current, { date, source })) return;
+        post.date = date;
+        dateSources.set(postId, source);
+      };
+      const mediaFilesMap = new Map<string, ArchiveFile>();
+      const discoveredProfilePics: { name: string, url: string }[] = [];
+      const allImageFiles: ArchiveFile[] = [];
+      
+      let localFullName = '';
+      let localBio = '';
+      let localExternalUrl = '';
+      let localFollowerCount = 0;
+      let localFollowingCount = 0;
+      let localProfilePic: string | null = null;
+
+      const checkIsStory = (obj: any): boolean => {
+        if (!obj) return false;
+        const typeName = obj.__typename || obj.typename || '';
+        return (obj.is_story === true || obj.is_reel_media === true || typeName.includes('Story') || obj.audience === "MediaAudience.DEFAULT" || obj.node_type === "StoryItem" || obj.product_type === "story" || typeName === "GraphStoryVideo" || typeName === "GraphStoryImage");
+      };
+
+      let currentUsername = archiveContext?.name || currentArchive?.name || detectedUsername;
+      
+      // If still no username (likely local folder), try to extract from path
+      if (!currentUsername && files[0]?.webkitRelativePath) {
+        const pathParts = files[0].webkitRelativePath.split(/[/\\]/);
+        if (pathParts.length > 1) {
+          currentUsername = pathParts[0];
+        }
+      }
+      
+      if (!currentUsername) currentUsername = 'archived_user';
+
+      let format: 'export' | 'instaloader' | 'json' | 'unknown' = 'unknown';
+      let jsonFiles: ArchiveFile[] = [];
+
+      // Pass 1: Indexing
+      for (let i = 0; i < files.length; i++) {
+        const file = files[i];
+        if (i % 100 === 0 || i === files.length - 1) {
+          setScannedCount(i + 1);
+          setScannedFilesLog(prev => [`Indexed ${file.name}`, ...prev.slice(0, 19)]);
+          // Yield to main thread
+          await new Promise(resolve => setTimeout(resolve, 0));
+        }
+        const lowerName = file.name.toLowerCase();
+        
+        if (lowerName.endsWith('.json') || lowerName.endsWith('.json.xz')) {
+          jsonFiles.push(file);
+          if (lowerName.includes('posts_1') || lowerName.includes('reels_1') || lowerName.includes('stories_1')) format = 'json';
+          continue;
+        }
+
+        if (EXPORT_RE.test(file.name)) format = 'export';
+        else if (INSTALOADER_RE.test(file.name)) format = 'instaloader';
+        // Highlight items match neither pattern, so a profile made up only of
+        // sidecar directories would otherwise never reach the filename parser.
+        else if (format === 'unknown' && file.source && file.source.kind !== 'posts') format = 'export';
+
+        if (lowerName.includes('_profile_pic.jpg') || (currentUsername && lowerName === `${currentUsername.toLowerCase()}.jpg`)) {
+          try {
+            const url = mintUrl(file, 'image/jpeg');
+            discoveredProfilePics.push({ name: file.name, url });
+            if (format === 'unknown' && lowerName.includes('_profile_pic.jpg')) format = 'instaloader';
+          } catch(e) {}
+        }
+
+        if (isMedia(file.name)) {
+          mediaFilesMap.set(file.webkitRelativePath || file.name, file);
+          if (isImage(file.name)) allImageFiles.push(file);
+        }
+      }
+
+      console.log(`[Scanner] Format Detection Complete. Result: ${format}. Media indexed: ${mediaFilesMap.size}`);
+
+      if (jsonFiles.length > 0 && (format === 'json' || format === 'instaloader')) {
+        setScanningPhase('Parsing');
+        for (let i = 0; i < jsonFiles.length; i++) {
+          const jsonFile = jsonFiles[i];
+          setScannedCount(i + 1);
+          setScannedFilesLog(prev => [`Parsing ${jsonFile.name}`, ...prev.slice(0, 19)]);
+          try {
+            const data = jsonFile.name.endsWith('.xz') ? await parseXZFile(jsonFile) : JSON.parse(await jsonFile.text());
+            if (!data) continue;
+            const items = Array.isArray(data) ? data : (data.media || [data]);
+            const isStoriesFile = jsonFile.name.toLowerCase().includes('stories');
+
+            if (data.node && (data.instaloader?.node_type === 'Profile' || data.node.__typename === 'User')) {
+              const node = data.node; const iphone = node.iphone_struct || {};
+              localFullName = node.full_name || ''; localBio = node.biography || iphone.biography || '';
+              localExternalUrl = node.external_url || '';
+              localFollowerCount = node.edge_followed_by?.count || iphone.follower_count || 0;
+              localFollowingCount = node.edge_follow?.count || iphone.following_count || 0;
+              if (!Array.isArray(data)) continue;
+            }
+
+            for (const [idx, item] of items.entries()) {
+              const mediaList = item.media || [item];
+              const postId = item.node?.id || item.id || item.title || `post_${idx}_${Date.now()}`;
+              const date = item.creation_timestamp ? new Date(item.creation_timestamp * 1000).toISOString().split('T')[0] : (item.node?.taken_at_timestamp ? new Date(item.node.taken_at_timestamp * 1000).toISOString().split('T')[0] : new Date().toISOString().split('T')[0]);
+              const isStory = isStoriesFile || checkIsStory(item) || checkIsStory(item.node) || checkIsStory(data.instaloader) || checkIsStory(item.node?.iphone_struct) || checkIsStory(item.iphone_struct) || (item.media && Array.isArray(item.media) && item.media.some((m: any) => checkIsStory(m)));
+              const post: Partial<Post> = { id: postId, date, username: currentUsername || 'archived_user', caption: item.title || item.node?.edge_media_to_caption?.edges?.[0]?.node?.text || item.node?.caption?.text || '', media: [], isStory };
+
+              for (const [mIdx, m] of mediaList.entries()) {
+                const uri = m.uri; let matchedFile: ArchiveFile | undefined;
+                if (uri) { for (const [path, f] of mediaFilesMap.entries()) { if (path.endsWith(uri) || uri.endsWith(path)) { matchedFile = f; break; } } }
+                if (!matchedFile) { const id = item.node?.id || item.id; if (id) { for (const [path, f] of mediaFilesMap.entries()) { if (f.name.includes(id)) { matchedFile = f; break; } } } }
+                if (!matchedFile) { 
+                  const jsonBase = jsonFile.name.substring(0, jsonFile.name.lastIndexOf('.'));
+                  for (const ext of ['mp4', 'webm', 'jpg', 'jpeg', 'png', 'webp', 'gif']) {
+                    const possibleName = `${jsonBase}.${ext}`;
+                    for (const [path, f] of mediaFilesMap.entries()) { if (f.name.toLowerCase() === possibleName.toLowerCase()) { matchedFile = f; break; } }
+                    if (matchedFile) break;
+                  }
+                }
+
+                if (matchedFile) {
+                  const type = isVideo(matchedFile.name) ? 'video' : 'image';
+                  const url = mintUrl(matchedFile, type === 'video' ? 'video/mp4' : 'image/jpeg');
+                  const existingMedia = post.media!.find(media => media.index === mIdx + 1);
+                  if (existingMedia) { if (type === 'video' && existingMedia.type === 'image') post.media = post.media!.map(media => media.index === mIdx + 1 ? { name: matchedFile!.name, path: mediaPath(matchedFile!), url, type, index: mIdx + 1, size: matchedFile!.size } : media); }
+                  else post.media!.push({ name: matchedFile.name, path: mediaPath(matchedFile), url, type, index: mIdx + 1, size: matchedFile.size });
+                }
+              }
+              if (post.media!.length > 0) postsMap.set(postId, post);
+            }
+          } catch (e) { console.error(`[Scanner] Error parsing JSON ${jsonFile.name}:`, e); }
+          // Yield to main thread
+          if (i % 10 === 0) await new Promise(resolve => setTimeout(resolve, 0));
+        }
+      } 
+      
+      if (format === 'export' || format === 'instaloader') {
+        setScanningPhase('Parsing');
+        const CHUNK_SIZE = 100;
+        for (let j_start = 0; j_start < files.length; j_start += CHUNK_SIZE) {
+          const end = Math.min(j_start + CHUNK_SIZE, files.length);
+          setScannedCount(j_start);
+          setScannedFilesLog(prev => [`Batch ${Math.floor(j_start/CHUNK_SIZE) + 1} processing...`, ...prev.slice(0, 19)]);
+          for (let j = j_start; j < end; j++) {
+            const file = files[j]; const lowerName = file.name.toLowerCase();
+            const kind = file.source?.kind ?? 'posts';
+            const parsed = parseArchiveFilename(file.name, kind, file.mtime);
+            if (!parsed) continue;
+
+            const { date, index, ext } = parsed;
+            const user = parsed.username || currentUsername || 'archived_user';
+            let isStory = parsed.isStory
+              || lowerName.includes('story')
+              || file.webkitRelativePath.toLowerCase().includes('stories');
+
+            const postId = scopedPostId(parsed.postId, kind, file.source?.dir);
+            if (kind === 'stories') isStory = true;
+            if (kind === 'highlight') isStory = false;
+
+            let post = postsMap.get(postId);
+            if (!post) {
+              post = { id: postId, date, username: user, caption: '', media: [], isStory, source: kind, highlightTitle: file.source?.title };
+              postsMap.set(postId, post);
+            }
+            else if (isStory) post.isStory = true;
+
+            // Files describing one post are scanned in directory order, not in
+            // order of trustworthiness, so every date goes through the ranking
+            // in post-dates.ts rather than last-write-wins.
+            applyDate(postId, post, date, parsed.dateFromMtime ? 'mtime' : 'filename');
+
+            const lowerExt = ext.toLowerCase();
+            if (lowerExt === 'txt') {
+              try { post.caption = await file.text(); } catch(e) {}
+            } else if (lowerExt === 'json' || lowerName.endsWith('.json.xz')) {
+              try {
+                const data = lowerName.endsWith('.xz') ? await parseXZFile(file) : JSON.parse(await file.text());
+                if (isGalleryDlSidecar(data)) {
+                  // The only format that states what a post is rather than
+                  // leaving it to be inferred from filenames.
+                  if (data.description) post.caption = data.description;
+                  const reel = sidecarIsReel(data);
+                  if (reel !== undefined) post.isReel = reel;
+                  if (data.type === 'story') post.isStory = true;
+                  applyDate(postId, post, sidecarDate(data), 'sidecar');
+                } else if (data) {
+                  const node = data.node || data; const iphone = node.iphone_struct || {};
+                  const captionText = node.edge_media_to_caption?.edges?.[0]?.node?.text || node.caption?.text || iphone.caption?.text || '';
+                  if (captionText) post.caption = captionText;
+                  if (checkIsStory(data) || checkIsStory(node) || checkIsStory(data.instaloader) || checkIsStory(iphone)) post.isStory = true;
+                }
+              } catch (e) {}
+            } else if (isMedia(file.name)) {
+              const type = isVideo(file.name) ? 'video' : 'image';
+              const url = mintUrl(file, type === 'video' ? 'video/mp4' : 'image/jpeg');
+              if (type === 'image') throttledSetScanningImage(url);
+              const existingMedia = post.media!.find(m => m.index === index);
+              if (existingMedia) { if (type === 'video' && existingMedia.type === 'image') post.media = post.media!.map(m => m.index === index ? { name: file.name, path: mediaPath(file), url, type, index, size: file.size } : m); }
+              else post.media!.push({ name: file.name, path: mediaPath(file), url, type, index, size: file.size });
+            }
+          }
+          await new Promise(resolve => setTimeout(resolve, 0));
+        }
+      }
+
+      if (postsMap.size === 0) {
+        console.log(`[Scanner] No posts found with standard patterns. Using mediaFilesMap: ${mediaFilesMap.size}`);
+        setScanningPhase('Parsing');
+        const genericGroupingMap = new Map<string, ArchiveFile[]>();
+        for (const [key, file] of mediaFilesMap.entries()) {
+          const match = file.name.match(/^(.*?)(?:(_|-|\s)+(\d+))?\.(.+)$/);
+          let baseName = file.name;
+          if (match && match[3]) { baseName = match[1].trim(); }
+          else { baseName = file.name.substring(0, file.name.lastIndexOf('.')); }
+          if (!genericGroupingMap.has(baseName)) genericGroupingMap.set(baseName, []);
+          genericGroupingMap.get(baseName)!.push(file);
+        }
+        console.log(`[Scanner] Generic grouping found ${genericGroupingMap.size} base groups.`);
+        let processedGroups = 0;
+        const groupEntries = Array.from(genericGroupingMap.entries());
+        for (const [baseName, groupFiles] of groupEntries) {
+          processedGroups++;
+          if (processedGroups % 10 === 0 || processedGroups === genericGroupingMap.size) {
+            setScannedCount(Math.floor((processedGroups / (genericGroupingMap.size || 1)) * (files.length || 1)));
+            setScannedFilesLog(prev => [`Grouping: ${baseName}`, ...prev.slice(0, 19)]);
+            await new Promise(resolve => setTimeout(resolve, 0));
+          }
+          groupFiles.sort((a, b) => {
+            const na = a.name.match(/[_-](\d+)\.\w+$/)?.[1];
+            const nb = b.name.match(/[_-](\d+)\.\w+$/)?.[1];
+            if (na && nb) return parseInt(na, 10) - parseInt(nb, 10);
+            return a.name.localeCompare(b.name);
+          });
+          const CAROUSEL_MAX = 20;
+          for (let j = 0; j < groupFiles.length; j += CAROUSEL_MAX) {
+            const batch = groupFiles.slice(j, j + CAROUSEL_MAX);
+            const partSuffix = groupFiles.length > CAROUSEL_MAX ? `_part${Math.floor(j/CAROUSEL_MAX) + 1}` : '';
+            const postId = `${baseName}${partSuffix}`;
+            const post: Post = { id: postId, date: new Date().toISOString().split('T')[0], username: currentUsername || 'archived_user', caption: baseName, media: [], thumbnail: '' };
+            for (const [idx, file] of batch.entries()) {
+              const type = isVideo(file.name) ? 'video' : 'image';
+              const url = mintUrl(file, type === 'video' ? 'video/mp4' : 'image/jpeg');
+              if (type === 'image') throttledSetScanningImage(url);
+              post.media.push({ name: file.name, path: mediaPath(file), url, type, index: idx + 1, size: file.size });
+            }
+            post.thumbnail = post.media[0].url;
+            postsMap.set(postId, post);
+          }
+        }
+      }
+
+      if (discoveredProfilePics.length > 0) {
+        discoveredProfilePics.sort((a, b) => b.name.localeCompare(a.name));
+        const urls = discoveredProfilePics.map(p => p.url);
+        localProfilePic = urls[0];
+        setProfileMetadata(prev => ({ ...prev, profilePic: localProfilePic, allProfilePics: urls }));
+      } else if (allImageFiles.length > 0) {
+        // Fallback: Use oldest image in archive as profile pic
+        allImageFiles.sort((a, b) => a.name.localeCompare(b.name));
+        const oldestFile = allImageFiles[0];
+        try {
+          const url = mintUrl(oldestFile, 'image/jpeg');
+          localProfilePic = url;
+          setProfileMetadata(prev => ({ ...prev, profilePic: localProfilePic, allProfilePics: [url] }));
+        } catch(e) {}
+      }
+
+      const finalUsername = currentUsername || 'archived_user';
+      const allItems = Array.from(postsMap.values()).filter(p => p.media && p.media.length > 0).map(p => {
+        const sortedMedia = p.media!.sort((a, b) => a.index - b.index);
+        return { ...p, username: (p.username === 'archived_user' || !p.username) ? finalUsername : p.username, media: sortedMedia, thumbnail: sortedMedia[0].url } as Post;
+      });
+
+      const byNewest = (a: Post, b: Post) => b.date.localeCompare(a.date);
+      // Highlights are story-shaped but live behind their own circles, so they
+      // are kept out of both the grid and the profile-ring story reel.
+      const highlights = allItems.filter(p => p.source === 'highlight').sort(byNewest);
+      const rest = allItems.filter(p => p.source !== 'highlight');
+      const posts = rest.filter(p => !p.isStory).sort(byNewest);
+      const stories = rest.filter(p => p.isStory).sort(byNewest);
+
+      setAllPosts(posts);
+      setAllStories(stories);
+      setAllHighlights(highlights);
+      setProfileMetadata(prev => ({
+        ...prev,
+        username: finalUsername,
+        fullName: localFullName,
+        bio: localBio,
+        followerCount: localFollowerCount,
+        followingCount: localFollowingCount,
+        externalUrl: localExternalUrl,
+        profilePic: localProfilePic || prev.profilePic,
+      }));
+
+      console.log(`[Scanner] Finalized ${posts.length} posts and ${stories.length} stories.`);
+
+      const archiveToCache = archiveContext || currentArchive;
+      const isLocal = !archiveToCache;
+      const cacheKey = archiveToCache ? archiveToCache.name : (finalUsername || 'local_archive');
+
+      if (cacheKey && (posts.length > 0 || stories.length > 0)) {
+        console.log(`[Cache] Saving data for ${cacheKey} to persistent storage...`);
+        let cacheThumbnail = localProfilePic;
+        if (isLocal && posts.length > 0 && posts[0].media[0].type === 'image') {
+          try {
+            const img = new Image(); img.src = posts[0].media[0].url;
+            await new Promise((res) => { img.onload = res; img.onerror = res; });
+            if (img.complete && img.width > 0) {
+              const canvas = document.createElement('canvas'); const size = 200;
+              canvas.width = size; canvas.height = size;
+              const ctx = canvas.getContext('2d');
+              if (ctx) { ctx.drawImage(img, 0, 0, img.width, img.height, 0, 0, size, size); cacheThumbnail = canvas.toDataURL('image/jpeg', 0.7); }
+            }
+          } catch (e) {}
+        }
+
+        const cacheData: CacheData = {
+          name: cacheKey, isLocal,
+          fileCount: (archiveToCache ? archiveToCache.fileCount : files.length) ?? files.length,
+          signature: archiveToCache?.signature,
+          posts: posts,
+          stories: stories,
+          highlights: highlights,
+          profileMetadata: {
+            username: finalUsername,
+            fullName: localFullName,
+            bio: localBio,
+            followerCount: localFollowerCount,
+            followingCount: localFollowingCount,
+            externalUrl: localExternalUrl,
+            // Local blob: URLs die with the document, so persist a data: URL for
+            // the dashboard card instead. Media URLs are rehydrated from `path`.
+            profilePic: isLocal ? cacheThumbnail : localProfilePic,
+            allProfilePics: isLocal ? (cacheThumbnail ? [cacheThumbnail] : []) : discoveredProfilePics.map(p => p.url)
+          },
+          hasDirectoryHandle: isLocal ? await hasDirectoryHandle(cacheKey) : false,
+          timestamp: Date.now()
+        };
+        try {
+          await setCachedArchive(cacheData);
+          console.log(`[Cache] Data saved successfully.`);
+          await refreshCachedArchives();
+        } catch (e) { console.error(`[Cache] Save error:`, e); }
+      }
+    } catch (err) { console.error(`[Scanner] Critical error during scan:`, err); } finally { setIsScanning(false); }
+  }, [currentArchive, detectedUsername, resetScannerState, refreshCachedArchives]);
+
+  return {
+    isScanning,
+    scanningPhase,
+    scannedCount,
+    totalFiles,
+    scannedFilesLog,
+    currentScanningImage,
+    allPosts,
+    allStories,
+    allHighlights,
+    profileMetadata,
+    handleFiles,
+    setAllPosts,
+    setAllStories,
+    setAllHighlights,
+    setProfileMetadata,
+    setIsScanning,
+    setScanningPhase,
+    setScannedCount,
+    setTotalFiles,
+    setScannedFilesLog,
+    setCurrentScanningImage,
+    resetScannerState,
+    registerUrl
+  };
+};

src/hooks/useIsMobile.ts

@@ -0,0 +1,27 @@
+import { useEffect, useState } from 'react';
+
+/** Matches Tailwind's `md` breakpoint, the point where the layout splits. */
+const MOBILE_QUERY = '(max-width: 767px)';
+
+/**
+ * True on phone-sized viewports.
+ *
+ * Drives more than styling: mobile opens posts as a scrollable feed page while
+ * desktop uses the modal, so this needs to be real state rather than a CSS
+ * media query.
+ */
+export const useIsMobile = () => {
+  const [isMobile, setIsMobile] = useState(
+    () => typeof window !== 'undefined' && window.matchMedia(MOBILE_QUERY).matches,
+  );
+
+  useEffect(() => {
+    const query = window.matchMedia(MOBILE_QUERY);
+    const onChange = (e: MediaQueryListEvent) => setIsMobile(e.matches);
+    query.addEventListener('change', onChange);
+    setIsMobile(query.matches);
+    return () => query.removeEventListener('change', onChange);
+  }, []);
+
+  return isMobile;
+};

src/hooks/useThumbnailQueue.ts

@@ -0,0 +1,128 @@
+import { useState, useCallback, useRef, useEffect } from 'react';
+import * as idb from 'idb-keyval';
+import { thumbKey } from '../lib/archive-cache';
+
+interface ThumbnailRequest {
+  id: string;
+  key: string;
+  url: string;
+  blob?: Blob;
+}
+
+const THUMBNAIL_WIDTH = 400;
+
+export const useThumbnailQueue = (archiveName: string) => {
+  const [cacheHits, setCacheHits] = useState<Map<string, string>>(new Map());
+  const queueRef = useRef<ThumbnailRequest[]>([]);
+  const isProcessingRef = useRef(false);
+  const workerRef = useRef<Worker | null>(null);
+
+  /**
+   * Mirrors `cacheHits` for reads inside callbacks.
+   *
+   * `requestThumbnail` is a dependency of every PostThumbnail effect, so it must
+   * keep a stable identity — closing over `cacheHits` state directly would give
+   * it a new identity per completed thumbnail and re-run the effect in all
+   * ~90 mounted thumbnails each time.
+   */
+  const cacheHitsRef = useRef<Map<string, string>>(new Map());
+  /** Blob URLs handed out for thumbnails, released when the archive changes. */
+  const createdUrlsRef = useRef<string[]>([]);
+
+  const publish = useCallback((id: string, url: string) => {
+    createdUrlsRef.current.push(url);
+    cacheHitsRef.current.set(id, url);
+    setCacheHits(new Map(cacheHitsRef.current));
+  }, []);
+
+  const processNext = useCallback(async () => {
+    if (isProcessingRef.current || queueRef.current.length === 0 || !workerRef.current) return;
+
+    isProcessingRef.current = true;
+    const request = queueRef.current.shift()!;
+
+    try {
+      // Re-check the store: the entry may have landed since being queued.
+      const cached = await idb.get(request.key);
+      if (cached instanceof Blob) {
+        publish(request.id, URL.createObjectURL(cached));
+        isProcessingRef.current = false;
+        processNext();
+        return;
+      }
+
+      let blob = request.blob;
+      if (!blob) {
+        const res = await fetch(request.url);
+        blob = await res.blob();
+      }
+
+      // One image at a time: decoding several 50MP+ files concurrently is a
+      // reliable way to OOM the tab.
+      workerRef.current.postMessage({ id: request.key, blob, width: THUMBNAIL_WIDTH });
+    } catch (err) {
+      console.error('[ThumbnailQueue] Failed to process:', request.id, err);
+      isProcessingRef.current = false;
+      processNext();
+    }
+  }, [publish]);
+
+  useEffect(() => {
+    workerRef.current = new Worker(new URL('../lib/thumbnail-worker.ts', import.meta.url), {
+      type: 'module'
+    });
+
+    workerRef.current.onmessage = async (e) => {
+      const { id: key, blob, error } = e.data;
+
+      if (!error && blob) {
+        const id = key.split(':').slice(2).join(':');
+        publish(id, URL.createObjectURL(blob));
+        try {
+          await idb.set(key, blob);
+        } catch (err) { /* quota exceeded; the in-memory hit still stands */ }
+      }
+
+      isProcessingRef.current = false;
+      processNext();
+    };
+
+    return () => {
+      workerRef.current?.terminate();
+    };
+  }, [publish, processNext]);
+
+  // Switching archives invalidates every thumbnail URL handed out so far.
+  useEffect(() => {
+    return () => {
+      queueRef.current = [];
+      for (const url of createdUrlsRef.current) {
+        try { URL.revokeObjectURL(url); } catch { /* already gone */ }
+      }
+      createdUrlsRef.current = [];
+      cacheHitsRef.current = new Map();
+      setCacheHits(new Map());
+    };
+  }, [archiveName]);
+
+  const requestThumbnail = useCallback(async (id: string, url: string, blob?: Blob) => {
+    if (cacheHitsRef.current.has(id)) return;
+
+    const key = thumbKey(archiveName, id);
+    const cached = await idb.get(key);
+    if (cached instanceof Blob) {
+      publish(id, URL.createObjectURL(cached));
+      return;
+    }
+
+    if (!queueRef.current.some(r => r.id === id)) {
+      queueRef.current.push({ id, key, url, blob });
+      processNext();
+    }
+  }, [archiveName, publish, processNext]);
+
+  return {
+    cacheHits,
+    requestThumbnail
+  };
+};

src/index.css

@@ -1,4 +1,5 @@
-@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Playfair+Display:ital,wght@0,400..900;1,400..900&display=swap');
+/* Self-hosted: no third-party font requests, works fully offline. */
+@import url('/fonts/fonts.css');
 @import "tailwindcss";
 
 @theme {

src/lib/archive-cache.ts

@@ -0,0 +1,170 @@
+import * as idb from 'idb-keyval';
+import { CacheData, Post } from '../types';
+import { DirectoryHandle, ensureReadPermission, filesFromDirectory } from './directory-handle';
+import { LocalArchiveFile } from './archive-files';
+
+/**
+ * Persistent archive cache.
+ *
+ * Keys are namespaced so that listing archives does not require deserializing
+ * every thumbnail blob in the store: `archive:` entries are metadata, `thumb:`
+ * entries are image blobs, `handle:` entries are directory handles.
+ */
+const ARCHIVE_PREFIX = 'archive:';
+const THUMB_PREFIX = 'thumb:';
+const HANDLE_PREFIX = 'handle:';
+
+export const archiveKey = (name: string) => `${ARCHIVE_PREFIX}${name}`;
+export const handleKey = (name: string) => `${HANDLE_PREFIX}${name}`;
+/** Thumbnails are scoped per archive; post IDs alone collide across archives. */
+export const thumbKey = (archive: string, postId: string) => `${THUMB_PREFIX}${archive}:${postId}`;
+
+export const getCachedArchive = (name: string): Promise<CacheData | undefined> =>
+  idb.get(archiveKey(name));
+
+export const setCachedArchive = (data: CacheData) => idb.set(archiveKey(data.name), data);
+
+/** Names of all cached archives, without loading their contents. */
+export const listCachedArchiveNames = async (): Promise<string[]> =>
+  (await idb.keys())
+    .map(String)
+    .filter(k => k.startsWith(ARCHIVE_PREFIX))
+    .map(k => k.slice(ARCHIVE_PREFIX.length));
+
+export const listCachedArchives = async (): Promise<CacheData[]> => {
+  const names = await listCachedArchiveNames();
+  const entries = await Promise.all(names.map(getCachedArchive));
+  return entries.filter((e): e is CacheData => Boolean(e));
+};
+
+/** Remove an archive along with its handle and every thumbnail it owns. */
+export const deleteCachedArchive = async (name: string) => {
+  const thumbPrefix = `${THUMB_PREFIX}${name}:`;
+  const stale = (await idb.keys()).map(String).filter(k => k.startsWith(thumbPrefix));
+  await idb.delMany([archiveKey(name), handleKey(name), ...stale]);
+};
+
+export const saveDirectoryHandle = (name: string, handle: DirectoryHandle) =>
+  idb.set(handleKey(name), handle);
+
+export const getDirectoryHandle = (name: string): Promise<DirectoryHandle | undefined> =>
+  idb.get(handleKey(name));
+
+/**
+ * One-time migration from the flat key layout (archive name as a bare key,
+ * `thumb_<postId>` for thumbnails).
+ *
+ * Old local entries are dropped rather than migrated: their media URLs are
+ * dead blob: URLs, so restoring them would render an archive of broken images.
+ */
+export const migrateLegacyCache = async () => {
+  const keys = (await idb.keys()).map(String);
+  const legacyThumbs = keys.filter(k => k.startsWith('thumb_'));
+  const legacyArchives = keys.filter(
+    k => !k.startsWith(ARCHIVE_PREFIX) && !k.startsWith(THUMB_PREFIX) &&
+         !k.startsWith(HANDLE_PREFIX) && !k.startsWith('thumb_')
+  );
+  if (!legacyThumbs.length && !legacyArchives.length) return;
+
+  const drop: string[] = [...legacyThumbs];
+  for (const key of legacyArchives) {
+    const data = await idb.get(key);
+    drop.push(key);
+    if (data && typeof data === 'object' && 'posts' in data && !(data as CacheData).isLocal) {
+      // Server archives keep working: their URLs are plain HTTP paths.
+      await setCachedArchive({ ...(data as CacheData), name: key });
+    }
+  }
+  await idb.delMany(drop);
+  console.log(`[Cache] Migrated legacy cache: dropped ${drop.length} stale keys.`);
+};
+
+/**
+ * Rebuild a server archive's media URLs, which are stable HTTP paths.
+ *
+ * `path` is relative to the archives root and already carries the source
+ * directory (which may be a sidecar such as `story - user`), so it is not
+ * prefixed with the archive name. Entries cached before `path` existed fall
+ * back to their stored URL.
+ */
+const rehydrateRemote = (posts: Post[]): Post[] =>
+  posts.map(post => {
+    const media = post.media.map(m => ({
+      ...m,
+      url: m.path ? `/archives/${encodeURI(m.path)}` : m.url,
+    }));
+    return { ...post, media, thumbnail: media[0]?.url ?? post.thumbnail };
+  });
+
+/**
+ * Rebuild a local archive's media URLs from a live directory handle, minting
+ * fresh blob: URLs for the paths recorded at scan time.
+ *
+ * Returns null when the folder is no longer reachable (permission declined, or
+ * the handle no longer resolves), signalling the caller to re-prompt.
+ */
+const rehydrateLocal = async (
+  posts: Post[],
+  handle: DirectoryHandle,
+  onUrl: (url: string) => void,
+): Promise<Post[] | null> => {
+  if (!(await ensureReadPermission(handle))) return null;
+
+  let files: LocalArchiveFile[];
+  try {
+    files = await filesFromDirectory(handle);
+  } catch (err) {
+    console.warn('[Cache] Directory handle no longer readable:', err);
+    return null;
+  }
+
+  const byPath = new Map(files.map(f => [f.webkitRelativePath, f]));
+
+  return posts.map(post => {
+    const media = post.media.map(m => {
+      const file = byPath.get(m.path);
+      if (!file) return { ...m, url: '' };
+      const url = file.createObjectUrl(m.type === 'video' ? 'video/mp4' : 'image/jpeg');
+      onUrl(url);
+      return { ...m, url };
+    });
+    return { ...post, media, thumbnail: media[0]?.url ?? '' };
+  });
+};
+
+export interface RestoredArchive {
+  posts: Post[];
+  stories: Post[];
+  highlights: Post[];
+  profileMetadata: CacheData['profileMetadata'];
+}
+
+/**
+ * Turn a cache entry back into displayable state.
+ *
+ * `onUrl` receives every blob: URL minted so the caller can revoke them later.
+ * Returns null if a local archive's folder can no longer be reached.
+ */
+export const restoreArchive = async (
+  data: CacheData,
+  onUrl: (url: string) => void,
+): Promise<RestoredArchive | null> => {
+  if (!data.isLocal) {
+    return {
+      posts: rehydrateRemote(data.posts),
+      stories: rehydrateRemote(data.stories),
+      highlights: rehydrateRemote(data.highlights ?? []),
+      profileMetadata: data.profileMetadata,
+    };
+  }
+
+  const handle = await getDirectoryHandle(data.name);
+  if (!handle) return null;
+
+  const posts = await rehydrateLocal(data.posts, handle, onUrl);
+  if (!posts) return null;
+  const stories = (await rehydrateLocal(data.stories, handle, onUrl)) ?? [];
+  const highlights = (await rehydrateLocal(data.highlights ?? [], handle, onUrl)) ?? [];
+
+  return { posts, stories, highlights, profileMetadata: data.profileMetadata };
+};

src/lib/archive-files.ts

@@ -0,0 +1,60 @@
+import { ArchiveFile, ArchiveSource } from '../types';
+
+export class LocalArchiveFile implements ArchiveFile {
+  /** Blob URLs minted here are revocable and must be released when done. */
+  readonly revocable = true;
+
+  /**
+   * @param explicitPath Set when the file came from the File System Access API,
+   *   whose File objects carry an empty webkitRelativePath.
+   */
+  constructor(private file: File, private explicitPath?: string) {}
+  get name() { return this.file.name; }
+  get webkitRelativePath() { return this.explicitPath ?? this.file.webkitRelativePath; }
+  get size() { return this.file.size; }
+  text() { return this.file.text(); }
+  arrayBuffer() { return this.file.arrayBuffer(); }
+
+  /**
+   * A blob: URL backed directly by the on-disk File.
+   *
+   * Deliberately does NOT go through arrayBuffer() — a File is already a Blob,
+   * so this hands the browser a disk-backed handle instead of pulling the whole
+   * file into memory. Doing otherwise means a 20GB archive tries to become 20GB
+   * of resident blobs.
+   *
+   * When the picker gave us no MIME type, slice() re-tags the blob with a hint.
+   * slice() is a zero-copy view, so this stays memory-free either way.
+   */
+  createObjectUrl(mimeHint?: string) {
+    const source = this.file.type || !mimeHint
+      ? this.file
+      : this.file.slice(0, this.file.size, mimeHint);
+    return URL.createObjectURL(source);
+  }
+}
+
+export class RemoteArchiveFile implements ArchiveFile {
+  /** Served over HTTP; there is no object URL to release. */
+  readonly revocable = false;
+
+  constructor(
+    public name: string,
+    public webkitRelativePath: string,
+    public size: number,
+    public url: string,
+    public source?: ArchiveSource,
+    public mtime?: number
+  ) {}
+  async text() {
+    const res = await fetch(this.url);
+    return res.text();
+  }
+  async arrayBuffer() {
+    const res = await fetch(this.url);
+    return res.arrayBuffer();
+  }
+  createObjectUrl() {
+    return this.url;
+  }
+}

src/lib/archive-grouping.test.ts

@@ -0,0 +1,89 @@
+import { describe, expect, it } from 'vitest';
+import { classifyDirectory, groupArchiveDirectories } from './archive-grouping';
+
+describe('classifyDirectory', () => {
+  it('treats a bare profile directory as the base', () => {
+    expect(classifyDirectory('4utumn07')).toEqual({
+      owner: '4utumn07',
+      source: { kind: 'posts', dir: '4utumn07' },
+    });
+  });
+
+  it('recognises a reels sidecar', () => {
+    expect(classifyDirectory('4utumn07 - reels')).toEqual({
+      owner: '4utumn07',
+      source: { kind: 'reels', dir: '4utumn07 - reels' },
+    });
+  });
+
+  it('recognises a stories sidecar', () => {
+    expect(classifyDirectory('story - dawn_petal')).toEqual({
+      owner: 'dawn_petal',
+      source: { kind: 'stories', dir: 'story - dawn_petal' },
+    });
+  });
+
+  it('splits highlight owner from title', () => {
+    const { owner, source } = classifyDirectory('story highlights - 4utumn07 - Sunstory');
+    expect(owner).toBe('4utumn07');
+    expect(source.kind).toBe('highlight');
+    expect(source.title).toBe('Sunstory');
+  });
+
+  it.each([
+    ['story highlights - theoldlyricmuseinsta - 💙1999-2005 era', 'theoldlyricmuseinsta', '💙1999-2005 era'],
+    ['story highlights - member_theworld - [Bracket]', 'member_theworld', '[Bracket]'],
+    ['story highlights - official_band - Tour Schedule', 'official_band', 'Tour Schedule'],
+    ['story highlights - 4utumn07 - Sketching⠀', '4utumn07', 'Sketching⠀'],
+    ['story highlights - official_band - A.B.C', 'official_band', 'A.B.C'],
+  ])('handles real-world title %s', (dir, owner, title) => {
+    const result = classifyDirectory(dir);
+    expect(result.owner).toBe(owner);
+    expect(result.source.title).toBe(title);
+  });
+
+  it('keeps titles containing " - " intact', () => {
+    // The username is matched as a non-space run, so only the first separator
+    // splits owner from title.
+    const { owner, source } = classifyDirectory('story highlights - user - a - b');
+    expect(owner).toBe('user');
+    expect(source.title).toBe('a - b');
+  });
+
+  it('does not mistake a profile with spaces for a sidecar', () => {
+    expect(classifyDirectory('Heejin_Bubble heejinmedia').source.kind).toBe('posts');
+  });
+});
+
+describe('groupArchiveDirectories', () => {
+  const dirs = [
+    '4utumn07',
+    '4utumn07 - reels',
+    'story - 4utumn07',
+    'story highlights - 4utumn07 - Sunstory',
+    'story highlights - 4utumn07 - Sketching⠀',
+    'kestrelsings',
+  ];
+
+  it('folds sidecars into their base profile', () => {
+    const groups = groupArchiveDirectories(dirs);
+    expect([...groups.keys()].sort()).toEqual(['4utumn07', 'kestrelsings']);
+    expect(groups.get('4utumn07')).toHaveLength(5);
+    expect(groups.get('kestrelsings')).toHaveLength(1);
+  });
+
+  it('orders sources posts, reels, stories, then highlights by title', () => {
+    const sources = groupArchiveDirectories(dirs).get('4utumn07')!;
+    expect(sources.map(s => s.kind)).toEqual(['posts', 'reels', 'stories', 'highlight', 'highlight']);
+    expect(sources.slice(3).map(s => s.title)).toEqual(['Sketching⠀', 'Sunstory']);
+  });
+
+  it('still groups a sidecar whose base profile is missing', () => {
+    const groups = groupArchiveDirectories(['story - orphan']);
+    expect(groups.get('orphan')).toEqual([{ kind: 'stories', dir: 'story - orphan' }]);
+  });
+
+  it('is stable for an empty archive root', () => {
+    expect(groupArchiveDirectories([]).size).toBe(0);
+  });
+});

src/lib/archive-grouping.ts

@@ -0,0 +1,71 @@
+/**
+ * Archive directory naming rules.
+ *
+ * Shared by the server (to fold sidecar directories into one profile) and the
+ * test suite. Kept free of Node built-ins so it can be imported from either.
+ */
+
+export type SourceKind = 'posts' | 'reels' | 'stories' | 'highlight';
+
+export interface ArchiveSource {
+  kind: SourceKind;
+  /** Directory name relative to the archives root. */
+  dir: string;
+  /** Highlight title, for kind === 'highlight'. */
+  title?: string;
+}
+
+/**
+ * Sidecar directories sit next to the profile directory they belong to:
+ *
+ *   4utumn07                                 -> posts     (base)
+ *   4utumn07 - reels                         -> reels
+ *   story - 4utumn07                         -> stories
+ *   story highlights - 4utumn07 - Sunstory   -> highlight "Sunstory"
+ *
+ * Instagram usernames cannot contain spaces, so matching the username as a
+ * run of non-space characters reliably separates it from a highlight title
+ * (titles may themselves contain spaces, dashes and emoji).
+ */
+export const classifyDirectory = (dirName: string): { owner: string; source: ArchiveSource } => {
+  const highlight = /^story highlights - ([^ ]+) - (.+)$/.exec(dirName);
+  if (highlight) {
+    return { owner: highlight[1], source: { kind: 'highlight', dir: dirName, title: highlight[2] } };
+  }
+
+  const stories = /^story - ([^ ]+)$/.exec(dirName);
+  if (stories) {
+    return { owner: stories[1], source: { kind: 'stories', dir: dirName } };
+  }
+
+  const reels = /^([^ ]+) - reels$/.exec(dirName);
+  if (reels) {
+    return { owner: reels[1], source: { kind: 'reels', dir: dirName } };
+  }
+
+  return { owner: dirName, source: { kind: 'posts', dir: dirName } };
+};
+
+const RANK: Record<SourceKind, number> = { posts: 0, reels: 1, stories: 2, highlight: 3 };
+
+/**
+ * Group the archive root's directories by profile.
+ *
+ * A sidecar whose owner has no base directory still forms a group of its own,
+ * so nothing becomes invisible just because the base profile is missing.
+ */
+export const groupArchiveDirectories = (dirNames: string[]): Map<string, ArchiveSource[]> => {
+  const groups = new Map<string, ArchiveSource[]>();
+
+  for (const dirName of dirNames) {
+    const { owner, source } = classifyDirectory(dirName);
+    if (!groups.has(owner)) groups.set(owner, []);
+    groups.get(owner)!.push(source);
+  }
+
+  for (const sources of groups.values()) {
+    sources.sort((a, b) => RANK[a.kind] - RANK[b.kind] || (a.title ?? '').localeCompare(b.title ?? ''));
+  }
+
+  return groups;
+};

src/lib/archive-index.test.ts

@@ -0,0 +1,34 @@
+import { describe, expect, it } from 'vitest';
+import { isSystemDirectory } from './archive-index';
+
+describe('isSystemDirectory', () => {
+  it.each([
+    ['@eaDir', 'Synology thumbnail/index metadata, written inside every folder'],
+    ['@tmp', 'Synology scratch'],
+    ['.sync', 'Resilio state'],
+    ['.DS_Store', 'macOS'],
+    ['#recycle', 'Synology deletions'],
+    ['#snapshot', 'Synology snapshots'],
+  ])('skips %s (%s)', name => {
+    expect(isSystemDirectory(name)).toBe(true);
+  });
+
+  it.each([
+    '4utumn07',
+    '4utumn07 - reels',
+    'story - dawn_petal',
+    'story highlights - official_band - A.B.C',
+    'story highlights - theoldlyricmuseinsta - 💙1999-2005 era',
+    'Heejin_Bubble heejinmedia',
+    'gallery-dl',
+    'posts',
+  ])('keeps %s', name => {
+    expect(isSystemDirectory(name)).toBe(false);
+  });
+
+  it('does not treat a leading underscore as a system directory', () => {
+    // `_gemini-plans` is filtered separately at the archive root only; nothing
+    // below the root should be excluded just for starting with an underscore.
+    expect(isSystemDirectory('_gemini-plans')).toBe(false);
+  });
+});

src/lib/archive-index.ts

@@ -0,0 +1,248 @@
+import fs from 'fs';
+import fsp from 'fs/promises';
+import path from 'path';
+import { ArchiveSource, SourceKind, groupArchiveDirectories } from './archive-grouping.js';
+
+/**
+ * On-disk archive index.
+ *
+ * Archives live on network storage where per-file `stat` costs ~1.4ms and does
+ * not parallelise well, so walking every file on each request is unaffordable:
+ * measured against a real 110k-file archive root, listing took ~52s.
+ *
+ * Directory `stat` is effectively free, so each source directory is indexed
+ * once and re-used until its mtime changes. The index is warmed in the
+ * background at startup and persisted, making steady-state requests instant.
+ */
+
+export interface IndexedFile {
+  path: string;
+  size: number;
+  mtime: number;
+  kind: SourceKind;
+  title?: string;
+}
+
+interface DirIndex {
+  dir: string;
+  /** Directory mtime the index was built from; the cache key. */
+  mtimeMs: number;
+  files: IndexedFile[];
+}
+
+const MEDIA_RE = /\.(jpg|jpeg|png|webp|gif|bmp|tiff|mp4|webm|ogv|mov)$/i;
+const STAT_CONCURRENCY = 16;
+
+/**
+ * Directories the walk must never descend into.
+ *
+ * NAS filesystems scatter sidecar metadata *inside* every folder, not just at
+ * the share root: Synology writes `@eaDir` (thumbnails and indexing data),
+ * `#recycle` holds deletions, and `.sync` is Resilio's state. Indexing those
+ * would count NAS thumbnails as archive media and spend a stat on each one —
+ * measured on a real share, `@eaDir` accounted for 12,516 of 123,023 files.
+ *
+ * The archive root is already filtered by prefix; this is the same rule applied
+ * at every level below it.
+ */
+export const isSystemDirectory = (name: string): boolean =>
+  name.startsWith('@') || name.startsWith('.') || name === '#recycle' || name === '#snapshot';
+
+export class ArchiveIndex {
+  private dirs = new Map<string, DirIndex>();
+  private inFlight = new Map<string, Promise<DirIndex>>();
+  private dirty = false;
+
+  constructor(private archivesDir: string, private cachePath: string) {}
+
+  /** Visible (non-system) directories at the archive root. */
+  private listRootDirs(): string[] {
+    return fs.readdirSync(this.archivesDir, { withFileTypes: true })
+      .filter(e => e.isDirectory() && !isSystemDirectory(e.name) && !e.name.startsWith('_'))
+      .map(e => e.name);
+  }
+
+  groups(): Map<string, ArchiveSource[]> {
+    return groupArchiveDirectories(this.listRootDirs());
+  }
+
+  private dirMtime(dir: string): number {
+    try {
+      return fs.statSync(path.join(this.archivesDir, dir)).mtimeMs;
+    } catch {
+      return 0;
+    }
+  }
+
+  /** Recursively list relative file paths without stat()ing them. */
+  private walk(absDir: string, base = ''): string[] {
+    let out: string[] = [];
+    let entries: fs.Dirent[];
+    try {
+      entries = fs.readdirSync(absDir, { withFileTypes: true });
+    } catch {
+      return out;
+    }
+    for (const entry of entries) {
+      if (isSystemDirectory(entry.name)) continue;
+      const rel = base ? `${base}/${entry.name}` : entry.name;
+      if (entry.isDirectory()) out = out.concat(this.walk(path.join(absDir, entry.name), rel));
+      else if (entry.isFile()) out.push(rel);
+    }
+    return out;
+  }
+
+  private async buildDir(source: ArchiveSource): Promise<DirIndex> {
+    const started = Date.now();
+    const mtimeMs = this.dirMtime(source.dir);
+    const absDir = path.join(this.archivesDir, source.dir);
+    const relPaths = this.walk(absDir);
+
+    // Only media needs a size (the client thumbnails anything over 1MiB), and
+    // only highlights need an mtime (their filenames carry no date). Skipping
+    // the rest avoids thousands of pointless round trips.
+    const needsStat = (rel: string) => MEDIA_RE.test(rel) || source.kind === 'highlight';
+
+    const files: IndexedFile[] = relPaths.map(rel => ({
+      path: `${source.dir}/${rel}`,
+      size: 0,
+      mtime: 0,
+      kind: source.kind,
+      ...(source.title ? { title: source.title } : {}),
+    }));
+
+    const targets = files.filter((_, i) => needsStat(relPaths[i]));
+    let cursor = 0;
+    const worker = async () => {
+      while (cursor < targets.length) {
+        const file = targets[cursor++];
+        try {
+          const stat = await fsp.stat(path.join(this.archivesDir, file.path));
+          file.size = stat.size;
+          file.mtime = stat.mtimeMs;
+        } catch { /* raced with a delete */ }
+      }
+    };
+    await Promise.all(Array.from({ length: STAT_CONCURRENCY }, worker));
+
+    console.log(
+      `[Index] ${source.dir}: ${files.length} files (${targets.length} statted) in ${((Date.now() - started) / 1000).toFixed(1)}s`
+    );
+    this.dirty = true;
+    return { dir: source.dir, mtimeMs, files };
+  }
+
+  /** Index for one source directory, rebuilding only if its mtime moved. */
+  private async ensureDir(source: ArchiveSource): Promise<DirIndex> {
+    const cached = this.dirs.get(source.dir);
+    const mtimeMs = this.dirMtime(source.dir);
+    if (cached && cached.mtimeMs === mtimeMs) return cached;
+
+    // Collapse concurrent requests for the same directory into one walk.
+    const existing = this.inFlight.get(source.dir);
+    if (existing) return existing;
+
+    const build = this.buildDir(source).then(index => {
+      this.dirs.set(source.dir, index);
+      this.inFlight.delete(source.dir);
+      return index;
+    }).catch(err => {
+      this.inFlight.delete(source.dir);
+      throw err;
+    });
+    this.inFlight.set(source.dir, build);
+    return build;
+  }
+
+  /** All files for one profile, across its base and sidecar directories. */
+  async filesFor(owner: string): Promise<IndexedFile[] | null> {
+    const sources = this.groups().get(owner);
+    if (!sources?.length) return null;
+    const indexes = await Promise.all(sources.map(s => this.ensureDir(s)));
+    return indexes.flatMap(i => i.files);
+  }
+
+  /**
+   * A cheap change signature for a profile, used by the client to decide
+   * whether its cached copy is stale. Built from directory mtimes only, so it
+   * costs one stat per source directory rather than a full walk.
+   */
+  signatureFor(sources: ArchiveSource[]): string {
+    return sources.map(s => `${s.dir}:${this.dirMtime(s.dir)}`).join('|');
+  }
+
+  /** File count for a profile, if its directories are already indexed. */
+  countFor(sources: ArchiveSource[]): number | null {
+    let total = 0;
+    for (const source of sources) {
+      const cached = this.dirs.get(source.dir);
+      if (!cached) return null;
+      total += cached.files.length;
+    }
+    return total;
+  }
+
+  /**
+   * Best-effort profile picture.
+   *
+   * Probes the conventional filenames first (one stat each) and only falls back
+   * to the indexed listing, so an unindexed archive still gets a thumbnail
+   * without triggering a walk.
+   */
+  thumbnailFor(owner: string, sources: ArchiveSource[]): string {
+    const base = sources.find(s => s.kind === 'posts') ?? sources[0];
+    if (!base) return '';
+
+    for (const candidate of [`${owner}.jpg`, `${owner}_profile_pic.jpg`, `${owner}.jpeg`, `${owner}.png`]) {
+      if (fs.existsSync(path.join(this.archivesDir, base.dir, candidate))) {
+        return `/archives/${encodeURI(`${base.dir}/${candidate}`)}`;
+      }
+    }
+
+    const cached = this.dirs.get(base.dir);
+    if (cached) {
+      const pick = cached.files.find(f => /_profile_pic\.jpg$/i.test(f.path))
+        ?? cached.files.find(f => /\.(jpg|jpeg|png|webp)$/i.test(f.path));
+      if (pick) return `/archives/${encodeURI(pick.path)}`;
+    }
+    return '';
+  }
+
+  /** Walk every directory once, in the background, so first opens are fast. */
+  async warm(): Promise<void> {
+    const started = Date.now();
+    const sources = [...this.groups().values()].flat();
+    console.log(`[Index] Warming ${sources.length} source directories...`);
+    for (const source of sources) {
+      try {
+        await this.ensureDir(source);
+      } catch (err) {
+        console.error(`[Index] Failed to index ${source.dir}:`, err);
+      }
+    }
+    await this.save();
+    console.log(`[Index] Warm complete in ${((Date.now() - started) / 1000).toFixed(1)}s`);
+  }
+
+  async load(): Promise<void> {
+    try {
+      const raw = await fsp.readFile(this.cachePath, 'utf8');
+      const parsed: DirIndex[] = JSON.parse(raw);
+      for (const entry of parsed) this.dirs.set(entry.dir, entry);
+      console.log(`[Index] Loaded ${this.dirs.size} directories from ${this.cachePath}`);
+    } catch {
+      console.log('[Index] No usable index cache; will build from scratch.');
+    }
+  }
+
+  async save(): Promise<void> {
+    if (!this.dirty) return;
+    try {
+      await fsp.writeFile(this.cachePath, JSON.stringify([...this.dirs.values()]), 'utf8');
+      this.dirty = false;
+      console.log(`[Index] Persisted ${this.dirs.size} directories to ${this.cachePath}`);
+    } catch (err) {
+      console.warn('[Index] Could not persist index (continuing in memory):', err);
+    }
+  }
+}

src/lib/archive-patterns.test.ts

@@ -0,0 +1,227 @@
+import { describe, expect, it } from 'vitest';
+import { canonicalItemId, parseArchiveFilename, scopedPostId } from './archive-patterns';
+
+describe('parseArchiveFilename — Instagram export format', () => {
+  it('parses a single-image post', () => {
+    expect(parseArchiveFilename('2023-04-19_4utumn07 - CrORBIcJJbM.mp4')).toEqual({
+      postId: 'CrORBIcJJbM',
+      date: '2023-04-19',
+      username: '4utumn07',
+      index: 1,
+      ext: 'mp4',
+      isStory: false,
+      dateFromMtime: false,
+    });
+  });
+
+  it('parses a carousel slide index', () => {
+    const parsed = parseArchiveFilename('2023-04-12_4utumn07 - Cq8LrxSJAJE - 3.jpg');
+    expect(parsed).toMatchObject({ postId: 'Cq8LrxSJAJE', index: 3, ext: 'jpg' });
+  });
+
+  it('groups a carousel under one post id', () => {
+    const ids = ['1', '2', '3'].map(
+      n => parseArchiveFilename(`2023-04-12_user - Cq8LrxSJAJE - ${n}.jpg`)!.postId,
+    );
+    expect(new Set(ids).size).toBe(1);
+  });
+
+  it('parses caption sidecar files', () => {
+    expect(parseArchiveFilename('2023-04-12_4utumn07 - Cq8LrxSJAJE.txt')).toMatchObject({
+      postId: 'Cq8LrxSJAJE',
+      ext: 'txt',
+    });
+  });
+
+  it('flags an explicit story suffix', () => {
+    expect(parseArchiveFilename('2023-04-12_user - ABC - story.jpg')?.isStory).toBe(true);
+  });
+
+  it('parses the story sidecar layout (date_user - N - shortcode)', () => {
+    // Files in `story - <user>` carry a per-day ordinal before the shortcode.
+    const parsed = parseArchiveFilename('2025-10-26_4utumn07 - 2 - DQRuDx9iW5Q.jpg', 'stories');
+    expect(parsed).toMatchObject({ date: '2025-10-26', username: '4utumn07', ext: 'jpg' });
+    expect(parsed!.postId).toContain('DQRuDx9iW5Q');
+  });
+
+  it('gives each story item a distinct id', () => {
+    const a = parseArchiveFilename('2026-08-13_u - 1 - Db-UTJcCUUr.mp4', 'stories')!.postId;
+    const b = parseArchiveFilename('2026-08-13_u - 2 - Db-oNJ1CWQ4.mp4', 'stories')!.postId;
+    expect(a).not.toBe(b);
+  });
+});
+
+describe('parseArchiveFilename — Instaloader format', () => {
+  it('parses a timestamped filename', () => {
+    expect(parseArchiveFilename('2024-01-01_12-00-00_UTC.jpg')).toMatchObject({
+      postId: '2024-01-01_12-00-00_UTC',
+      date: '2024-01-01',
+      index: 1,
+    });
+  });
+
+  it('parses the carousel suffix', () => {
+    expect(parseArchiveFilename('2024-01-01_12-00-00_UTC_2.jpg')?.index).toBe(2);
+  });
+
+  it('flags the story suffix', () => {
+    expect(parseArchiveFilename('2024-01-01_12-00-00_UTC_story.jpg')?.isStory).toBe(true);
+  });
+});
+
+describe('parseArchiveFilename — story highlights', () => {
+  it('parses the dateless highlight layout', () => {
+    expect(parseArchiveFilename('4utumn07 - C5dQPEYpd9W.mp4', 'highlight')).toMatchObject({
+      postId: 'C5dQPEYpd9W',
+      username: '4utumn07',
+      ext: 'mp4',
+      isStory: false,
+    });
+  });
+
+  it('dates a highlight from mtime when the filename has none', () => {
+    const mtime = Date.UTC(2024, 4, 17, 12, 0, 0);
+    expect(parseArchiveFilename('user - ABC.jpg', 'highlight', mtime)?.date).toBe('2024-05-17');
+  });
+
+  it('leaves the date empty when no mtime is available', () => {
+    expect(parseArchiveFilename('user - ABC.jpg', 'highlight')?.date).toBe('');
+  });
+
+  it('does not apply the loose highlight pattern outside highlight directories', () => {
+    // Would otherwise swallow ordinary "a - b.jpg" filenames.
+    expect(parseArchiveFilename('user - ABC.jpg', 'posts')).toBeNull();
+  });
+});
+
+describe('parseArchiveFilename — non-matching files', () => {
+  it.each(['4utumn07.jpg', 'profile_pic.jpg', 'README.md', 'no-separator.png'])(
+    'returns null for %s',
+    name => expect(parseArchiveFilename(name)).toBeNull(),
+  );
+});
+
+describe('scopedPostId', () => {
+  it('leaves base-profile ids untouched so permalinks keep working', () => {
+    expect(scopedPostId('Cq8LrxSJAJE', 'posts')).toBe('Cq8LrxSJAJE');
+  });
+
+  it('namespaces sidecar ids by directory', () => {
+    expect(scopedPostId('C5dQ', 'highlight', 'story highlights - u - Sunstory'))
+      .toBe('story highlights - u - Sunstory/C5dQ');
+  });
+
+  it('keeps the same shortcode distinct across sources', () => {
+    const inPosts = scopedPostId('ABC', 'posts');
+    const inHighlight = scopedPostId('ABC', 'highlight', 'story highlights - u - H');
+    expect(inPosts).not.toBe(inHighlight);
+  });
+});
+
+/**
+ * gallery-dl is replacing JDownloader as the fetcher (docs/gallery-dl.md).
+ * Its naming differs cosmetically, and these cases pin down that the two
+ * interoperate so a mixed archive parses identically.
+ */
+describe('gallery-dl / JDownloader naming interop', () => {
+  it('treats a single-media post the same with or without an index', () => {
+    const jd2 = parseArchiveFilename('2023-04-19_4utumn07 - CrORBIcJJbM.mp4')!;
+    const gdl = parseArchiveFilename('2023-04-19_4utumn07 - CrORBIcJJbM - 1.mp4')!;
+    expect(jd2.postId).toBe(gdl.postId);
+    expect(jd2.index).toBe(gdl.index);
+    expect(jd2.index).toBe(1);
+  });
+
+  it('normalises zero-padded carousel indices', () => {
+    // JD2 pads to the width of the media count (10+ items -> "01"), and
+    // gallery-dl's count can be one higher, so the same post may be padded
+    // by one tool and not the other.
+    expect(parseArchiveFilename('2024-04-17_4utumn07 - C53YPQzp7Wj - 09.jpg')!.index).toBe(9);
+    expect(parseArchiveFilename('2024-04-17_4utumn07 - C53YPQzp7Wj - 9.jpg')!.index).toBe(9);
+    expect(parseArchiveFilename('2023-11-03_4utumn07 - CzM8Uf6B6H_ - 01.jpg')!.index).toBe(1);
+  });
+
+  it('reads a gallery-dl story name, which carries a per-item shortcode', () => {
+    const p = parseArchiveFilename('2026-08-16_official_band - DcF9OyhBJ1H.jpg', 'stories')!;
+    expect(p.postId).toBe('DcF9OyhBJ1H');
+    expect(p.date).toBe('2026-08-16');
+  });
+
+  it('gives a dated highlight a real date instead of the mtime fallback', () => {
+    const mtime = Date.parse('2026-08-17T00:00:00Z');
+    const undated = parseArchiveFilename('4utumn07 - C-IImhvpFuk.jpg', 'highlight', mtime)!;
+    const dated = parseArchiveFilename('2024-08-04_4utumn07 - C-IImhvpFuk.jpg', 'highlight', mtime)!;
+    // Same item either way, so re-fetching cannot split it into two posts.
+    expect(dated.postId).toBe(undated.postId);
+    expect(undated.date).toBe('2026-08-17');
+    expect(dated.date).toBe('2024-08-04');
+  });
+});
+
+/**
+ * Highlights are the only files with no date in the name, so they fall back to
+ * mtime — which is when the file was written, not when it was posted. Callers
+ * need to know the difference to let a real date win.
+ */
+describe('dateFromMtime', () => {
+  const mtime = Date.parse('2026-08-17T00:00:00Z');
+
+  it('flags an undated highlight name as mtime-dated', () => {
+    const p = parseArchiveFilename('4utumn07 - C-IImhvpFuk.jpg', 'highlight', mtime)!;
+    expect(p.date).toBe('2026-08-17');
+    expect(p.dateFromMtime).toBe(true);
+  });
+
+  it('does not flag a highlight that carries its own date', () => {
+    const p = parseArchiveFilename('2024-08-04_4utumn07 - C-IImhvpFuk.jpg', 'highlight', mtime)!;
+    expect(p.date).toBe('2024-08-04');
+    expect(p.dateFromMtime).toBe(false);
+  });
+
+  it('never flags ordinary post or Instaloader names', () => {
+    expect(parseArchiveFilename('2023-04-19_u - ABC.mp4', 'posts', mtime)!.dateFromMtime).toBe(false);
+    expect(parseArchiveFilename('2024-01-01_12-00-00_UTC.jpg', 'posts', mtime)!.dateFromMtime).toBe(false);
+  });
+
+  it('leaves the date empty rather than guessing when no mtime is given', () => {
+    const p = parseArchiveFilename('4utumn07 - C-IImhvpFuk.jpg', 'highlight')!;
+    expect(p.date).toBe('');
+    expect(p.dateFromMtime).toBe(false);
+  });
+});
+
+/**
+ * JDownloader wrote story-shaped names for highlights during one period, so
+ * the same item exists under two conventions. They must be one post.
+ */
+describe('canonicalItemId', () => {
+  it('collapses the two highlight naming conventions onto one id', () => {
+    const dir = 'story highlights - 4utumn07 - Sunstory';
+    const undated = parseArchiveFilename('4utumn07 - C5dQPEYpd9W.mp4', 'highlight', 1)!;
+    const dated = parseArchiveFilename('2024-04-07_4utumn07 - 01 - C5dQPEYpd9W.mp4', 'highlight')!;
+    expect(scopedPostId(dated.postId, 'highlight', dir))
+      .toBe(scopedPostId(undated.postId, 'highlight', dir));
+  });
+
+  it('does the same for stories', () => {
+    const a = parseArchiveFilename('2025-10-26_u - 2 - DQRuDx9iW5Q.jpg', 'stories')!;
+    expect(scopedPostId(a.postId, 'stories', 'story - u')).toBe('story - u/DQRuDx9iW5Q');
+  });
+
+  it('keeps distinct story items distinct', () => {
+    const a = parseArchiveFilename('2026-08-13_u - 1 - Db-UTJcCUUr.mp4', 'stories')!;
+    const b = parseArchiveFilename('2026-08-13_u - 2 - Db-oNJ1CWQ4.mp4', 'stories')!;
+    expect(scopedPostId(a.postId, 'stories', 'story - u'))
+      .not.toBe(scopedPostId(b.postId, 'stories', 'story - u'));
+  });
+
+  it('leaves a shortcode that merely starts with digits alone', () => {
+    expect(canonicalItemId('4utumn07')).toBe('4utumn07');
+    expect(canonicalItemId('C5dQPEYpd9W')).toBe('C5dQPEYpd9W');
+    expect(canonicalItemId('12345')).toBe('12345');
+  });
+
+  it('does not touch posts, whose ids are permalinks', () => {
+    expect(scopedPostId('01 - ABC', 'posts')).toBe('01 - ABC');
+  });
+});

src/lib/archive-patterns.ts

@@ -0,0 +1,135 @@
+import { SourceKind } from '../types';
+
+/**
+ * Filename parsing rules for the archive formats the viewer understands.
+ *
+ * Kept as pure functions so the riskiest part of the scanner — deriving post
+ * identity, date and carousel order from a filename — can be tested directly.
+ */
+
+/** Instagram export: `2023-04-12_user - Cq8LrxSJAJE - 2.jpg` */
+export const EXPORT_RE = /^(\d{4}-\d{2}-\d{2})_(.+?) - (.+?)(?: - (\d+))?(?: - (story))?\.(.+)$/;
+
+/** Instaloader: `2024-01-01_12-00-00_UTC_2.jpg` */
+export const INSTALOADER_RE = /^(\d{4}-\d{2}-\d{2}_\d{2}-\d{2}-\d{2}_UTC)(?:_(\d+))?(?:_(story))?\.(.+)$/;
+
+/**
+ * Story highlight: `user - C5dQPEYpd9W.mp4` — no date prefix.
+ *
+ * Loose enough to match ordinary filenames, so it is only applied to files the
+ * server has already tagged as coming from a highlight directory.
+ */
+export const HIGHLIGHT_RE = /^(.+?) - ([A-Za-z0-9_-]+)\.(\w+)$/;
+
+export interface ParsedFilename {
+  postId: string;
+  /** ISO date (YYYY-MM-DD), or '' when the filename carries none. */
+  date: string;
+  username: string;
+  /** 1-based carousel position. */
+  index: number;
+  ext: string;
+  isStory: boolean;
+  /**
+   * True when `date` is the file's mtime rather than anything Instagram said.
+   *
+   * Only highlights fetched by JDownloader lack a date in the filename, and
+   * their mtime is just when the file was written. Callers should let any real
+   * date win over this one — the same item is often also present under a
+   * gallery-dl name that does carry the date.
+   */
+  dateFromMtime: boolean;
+}
+
+/**
+ * Parse an archive filename into post identity.
+ *
+ * `kind` selects which patterns apply; `mtime` supplies a date for formats that
+ * have none (highlights), so those items still sort and render sensibly.
+ * Returns null when no pattern matches — e.g. a profile picture.
+ */
+export const parseArchiveFilename = (
+  fileName: string,
+  kind: SourceKind = 'posts',
+  mtime?: number,
+): ParsedFilename | null => {
+  const exp = EXPORT_RE.exec(fileName);
+  if (exp) {
+    const [, date, username, postId, indexStr, story, ext] = exp;
+    return {
+      postId,
+      date,
+      username,
+      index: indexStr ? parseInt(indexStr, 10) : 1,
+      ext,
+      isStory: Boolean(story),
+      dateFromMtime: false,
+    };
+  }
+
+  const ins = INSTALOADER_RE.exec(fileName);
+  if (ins) {
+    const [, postId, indexStr, story, ext] = ins;
+    return {
+      postId,
+      date: postId.split('_')[0],
+      username: '',
+      index: indexStr ? parseInt(indexStr, 10) : 1,
+      ext,
+      isStory: Boolean(story),
+      dateFromMtime: false,
+    };
+  }
+
+  if (kind === 'highlight') {
+    const hl = HIGHLIGHT_RE.exec(fileName);
+    if (hl) {
+      const [, username, shortcode, ext] = hl;
+      return {
+        postId: shortcode,
+        date: mtime ? new Date(mtime).toISOString().split('T')[0] : '',
+        username,
+        index: 1,
+        ext,
+        isStory: false,
+        dateFromMtime: Boolean(mtime),
+      };
+    }
+  }
+
+  return null;
+};
+
+/**
+ * A leading per-day ordinal on a story or highlight id: `01 - C5dQPEYpd9W`.
+ *
+ * JDownloader wrote story-shaped names for highlights during one period of its
+ * life, so the same item exists as both `user - CODE.jpg` and
+ * `date_user - 01 - CODE.jpg`. Those parse to different ids and the viewer
+ * shows the item twice. The ordinal carries no information the shortcode does
+ * not — it is a position within a day's stories, and the shortcode is already
+ * unique — so it is dropped.
+ */
+const LEADING_ORDINAL = /^\d+ - (?=[A-Za-z0-9_-]+$)/;
+
+/** Strip the ordinal so both naming conventions land on the same post. */
+export const canonicalItemId = (postId: string): string =>
+  postId.replace(LEADING_ORDINAL, '');
+
+/**
+ * Namespace a post ID by its source directory.
+ *
+ * Base-profile IDs are left untouched so existing permalinks keep working;
+ * sidecar IDs are prefixed so a shortcode appearing in both the profile and a
+ * highlight stays two distinct posts.
+ *
+ * Story and highlight ids are canonicalised first, so an item fetched under
+ * two different naming conventions is one post rather than two.
+ */
+export const scopedPostId = (postId: string, kind: SourceKind, dir?: string): string => {
+  if (kind === 'posts') return postId;
+  const id = (kind === 'stories' || kind === 'highlight')
+    ? canonicalItemId(postId)
+    : postId;
+  return `${dir ?? kind}/${id}`;
+};

src/lib/directory-handle.ts

@@ -0,0 +1,86 @@
+import { LocalArchiveFile } from './archive-files';
+
+/**
+ * File System Access API helpers.
+ *
+ * A `blob:` URL dies with the document, so a cached local archive whose media
+ * URLs are blob: URLs is worthless after a reload. A FileSystemDirectoryHandle,
+ * by contrast, is structured-cloneable and survives in IndexedDB — so we can
+ * re-open the same folder on a return visit and mint fresh URLs from it.
+ *
+ * Only Chromium implements showDirectoryPicker today; callers must handle the
+ * unsupported case by falling back to the <input webkitdirectory> flow.
+ */
+
+// Minimal typings — TS's lib.dom does not ship these in the configured version.
+type PermissionState = 'granted' | 'denied' | 'prompt';
+interface FileSystemHandlePermissionDescriptor { mode?: 'read' | 'readwrite' }
+export interface DirectoryHandle {
+  name: string;
+  kind: 'directory';
+  values(): AsyncIterableIterator<DirectoryHandle | FileHandle>;
+  queryPermission?(d?: FileSystemHandlePermissionDescriptor): Promise<PermissionState>;
+  requestPermission?(d?: FileSystemHandlePermissionDescriptor): Promise<PermissionState>;
+}
+interface FileHandle {
+  name: string;
+  kind: 'file';
+  getFile(): Promise<File>;
+}
+
+export const isDirectoryPickerSupported = () =>
+  typeof window !== 'undefined' && 'showDirectoryPicker' in window;
+
+export const pickDirectory = async (): Promise<DirectoryHandle | null> => {
+  if (!isDirectoryPickerSupported()) return null;
+  try {
+    return await (window as any).showDirectoryPicker({ mode: 'read' });
+  } catch (err) {
+    // AbortError simply means the user dismissed the picker.
+    return null;
+  }
+};
+
+/**
+ * Confirm we may still read this handle. Returns false when the user declines
+ * or the grant has lapsed, in which case the caller should re-prompt.
+ *
+ * `requestPermission` must be called from a user gesture, so only call this
+ * while handling a click.
+ */
+export const ensureReadPermission = async (handle: DirectoryHandle): Promise<boolean> => {
+  try {
+    if (!handle.queryPermission) return true;
+    if ((await handle.queryPermission({ mode: 'read' })) === 'granted') return true;
+    if (!handle.requestPermission) return false;
+    return (await handle.requestPermission({ mode: 'read' })) === 'granted';
+  } catch {
+    return false;
+  }
+};
+
+/**
+ * Recursively collect every file in the directory.
+ *
+ * Paths are prefixed with the root directory's name so they line up with the
+ * `webkitRelativePath` values produced by <input webkitdirectory>, keeping
+ * cached media paths valid regardless of which picker created them.
+ */
+export const filesFromDirectory = async (handle: DirectoryHandle): Promise<LocalArchiveFile[]> => {
+  const out: LocalArchiveFile[] = [];
+
+  const walk = async (dir: DirectoryHandle, prefix: string) => {
+    for await (const entry of dir.values()) {
+      const entryPath = `${prefix}/${entry.name}`;
+      if (entry.kind === 'directory') {
+        await walk(entry as DirectoryHandle, entryPath);
+      } else {
+        const file = await (entry as FileHandle).getFile();
+        out.push(new LocalArchiveFile(file, entryPath));
+      }
+    }
+  };
+
+  await walk(handle, handle.name);
+  return out;
+};

src/lib/gallery-dl-sidecar.test.ts

@@ -0,0 +1,82 @@
+import { describe, expect, it } from 'vitest';
+import {
+  GalleryDlSidecar, isGalleryDlSidecar, sidecarDate, sidecarIsReel, sidecarSource,
+} from './gallery-dl-sidecar';
+
+// Trimmed from real files published to the archive on 2026-08-16.
+const REEL: GalleryDlSidecar = {
+  post_shortcode: 'Db-lNCoib9m', post_id: '3962768346034323302', type: 'reel',
+  date: '2026-08-13 11:00:44', post_date: '2026-08-13 11:00:44',
+  username: 'official_band', fullname: 'Official ARTMS',
+  description: 'Dancing in the spotlight', count: 1, likes: 22914,
+};
+const FEED_VIDEO: GalleryDlSidecar = { ...REEL, post_shortcode: 'DbdG9L9jU4m', type: 'post', count: 2 };
+const HIGHLIGHT: GalleryDlSidecar = {
+  post_shortcode: 'BATVdRZi_3', post_id: '18099435932626935', type: 'highlight',
+  date: '2026-08-08 16:22:09', username: 'official_band', count: 154,
+};
+
+describe('isGalleryDlSidecar', () => {
+  it('accepts a real sidecar', () => {
+    expect(isGalleryDlSidecar(REEL)).toBe(true);
+    expect(isGalleryDlSidecar(HIGHLIGHT)).toBe(true);
+  });
+
+  it('rejects an Instaloader GraphQL payload', () => {
+    expect(isGalleryDlSidecar({ node: { __typename: 'GraphVideo', shortcode: 'x' } })).toBe(false);
+    expect(isGalleryDlSidecar({ __typename: 'GraphImage', post_shortcode: 'x', type: 'post' })).toBe(false);
+  });
+
+  it('rejects an Instagram export manifest', () => {
+    expect(isGalleryDlSidecar({ media: [{ uri: 'a.jpg' }] })).toBe(false);
+    expect(isGalleryDlSidecar([{ media: [] }])).toBe(false);
+  });
+
+  it('rejects junk', () => {
+    for (const v of [null, undefined, 0, '', 'string', {}, { post_shortcode: 'x' }]) {
+      expect(isGalleryDlSidecar(v)).toBe(false);
+    }
+  });
+});
+
+describe('sidecarDate', () => {
+  it('takes the day from the timestamp', () => {
+    expect(sidecarDate(REEL)).toBe('2026-08-13');
+  });
+
+  it('falls back to post_date', () => {
+    expect(sidecarDate({ post_shortcode: 'x', post_date: '2024-01-02 03:04:05' })).toBe('2024-01-02');
+  });
+
+  it('returns empty when there is no usable date', () => {
+    expect(sidecarDate({ post_shortcode: 'x' })).toBe('');
+    expect(sidecarDate({ post_shortcode: 'x', date: 'not a date' })).toBe('');
+  });
+});
+
+describe('sidecarIsReel', () => {
+  it('distinguishes a reel from an ordinary feed video', () => {
+    // Both are single mp4s -- the lone-video heuristic cannot tell them apart.
+    expect(sidecarIsReel(REEL)).toBe(true);
+    expect(sidecarIsReel(FEED_VIDEO)).toBe(false);
+  });
+
+  it('declines to answer for stories and highlights', () => {
+    expect(sidecarIsReel(HIGHLIGHT)).toBeUndefined();
+    expect(sidecarIsReel({ post_shortcode: 'x', type: 'story' as const })).toBeUndefined();
+    expect(sidecarIsReel({ post_shortcode: 'x' })).toBeUndefined();
+  });
+});
+
+describe('sidecarSource', () => {
+  it('maps type onto the archive source kinds', () => {
+    expect(sidecarSource(REEL)).toBe('reels');
+    expect(sidecarSource(FEED_VIDEO)).toBe('posts');
+    expect(sidecarSource(HIGHLIGHT)).toBe('highlight');
+    expect(sidecarSource({ post_shortcode: 'x', type: 'story' as const })).toBe('stories');
+  });
+
+  it('is undefined for an unknown type', () => {
+    expect(sidecarSource({ post_shortcode: 'x' })).toBeUndefined();
+  });
+});

src/lib/gallery-dl-sidecar.ts

@@ -0,0 +1,87 @@
+import { SourceKind } from '../types';
+
+/**
+ * gallery-dl `.json` metadata sidecars.
+ *
+ * Written one per post next to the media (see docs/gallery-dl.md). This is the
+ * only source in any archive format that states outright what a post *is* —
+ * `type` is Instagram's own classification, the `product_type: "clips"` signal
+ * carried through the listing response. Everything else the viewer knows about
+ * reels is guesswork from filenames and directory names.
+ *
+ * Deliberately separate from the two older JSON shapes the scanner reads:
+ *
+ *   Instagram export   `posts_1.json`, an array of entries with `media`
+ *   Instaloader        `.json.xz`, a GraphQL node under `node`
+ *   gallery-dl         this — flat, no wrapper
+ */
+export interface GalleryDlSidecar {
+  post_shortcode: string;
+  post_id?: string;
+  /** Instagram's own classification of the post. */
+  type?: 'post' | 'reel' | 'story' | 'highlight';
+  /** Local-time "YYYY-MM-DD HH:MM:SS" — gallery-dl is configured to emit local. */
+  date?: string;
+  post_date?: string;
+  username?: string;
+  fullname?: string;
+  description?: string;
+  count?: number;
+  likes?: number;
+  post_url?: string;
+}
+
+/**
+ * Recognise a gallery-dl sidecar.
+ *
+ * Checked structurally rather than by filename, because the older formats are
+ * also plain `.json`. `node` and `__typename` are what an Instaloader or
+ * export payload carries, and their absence is what makes this shape
+ * unambiguous.
+ */
+export const isGalleryDlSidecar = (data: unknown): data is GalleryDlSidecar => {
+  if (!data || typeof data !== 'object' || Array.isArray(data)) return false;
+  const o = data as Record<string, unknown>;
+  return typeof o.post_shortcode === 'string'
+    && typeof o.type === 'string'
+    && o.node === undefined
+    && o.__typename === undefined
+    && o.media === undefined;
+};
+
+/** The ISO date (YYYY-MM-DD) a sidecar reports, or '' if it carries none. */
+export const sidecarDate = (s: GalleryDlSidecar): string => {
+  const raw = s.date || s.post_date || '';
+  const day = raw.slice(0, 10);
+  return /^\d{4}-\d{2}-\d{2}$/.test(day) ? day : '';
+};
+
+/**
+ * Whether the sidecar says this post is a reel.
+ *
+ * Returns undefined rather than false for stories and highlights: those are
+ * neither reels nor grid posts, and answering "no" would let them be counted
+ * as ordinary posts.
+ */
+export const sidecarIsReel = (s: GalleryDlSidecar): boolean | undefined => {
+  if (s.type === 'reel') return true;
+  if (s.type === 'post') return false;
+  return undefined;
+};
+
+/**
+ * Which source kind the sidecar implies, for cross-checking the directory.
+ *
+ * A reel shared to the profile grid legitimately appears under `posts`, so a
+ * disagreement is not an error — the directory says where the file was
+ * fetched from, `type` says what Instagram considers it.
+ */
+export const sidecarSource = (s: GalleryDlSidecar): SourceKind | undefined => {
+  switch (s.type) {
+    case 'reel': return 'reels';
+    case 'post': return 'posts';
+    case 'story': return 'stories';
+    case 'highlight': return 'highlight';
+    default: return undefined;
+  }
+};

src/lib/motion.ts

@@ -0,0 +1,44 @@
+import type { Transition } from 'motion/react';
+
+/**
+ * Shared motion vocabulary, tuned to feel like a native iOS app.
+ *
+ * Two rules do most of the work:
+ *  - UIKit animates with springs, not fixed-duration easing, so gestures hand
+ *    their exit velocity to the animation and motion continues rather than
+ *    restarting.
+ *  - iOS springs are critically damped. They settle firmly with no visible
+ *    bounce; overshoot reads as "web animation", not "native".
+ */
+
+/** The curve UIKit uses for sheet presentation. */
+export const IOS_EASE = [0.32, 0.72, 0, 1] as const;
+
+/** Moving between peers: carousel slides, next/previous post. */
+export const NAVIGATE: Transition = { type: 'spring', stiffness: 420, damping: 40, mass: 1 };
+
+/** Presenting or dismissing a surface. Slightly softer than navigation. */
+export const PRESENT: Transition = { type: 'spring', stiffness: 320, damping: 34, mass: 1 };
+
+/** Backdrops and cross-fades, where a spring would feel fussy. */
+export const FADE: Transition = { duration: 0.28, ease: IOS_EASE };
+
+/** Touch-down feedback. Fast enough to feel like a direct response. */
+export const PRESS: Transition = { type: 'spring', stiffness: 600, damping: 30 };
+
+/**
+ * Continue a drag into its animation.
+ *
+ * Handing the gesture's exit velocity to the spring is what separates "the
+ * sheet kept moving because I flicked it" from "the sheet started a new
+ * animation once I let go".
+ */
+export const withVelocity = (velocity: number, base: Transition = NAVIGATE): Transition => ({
+  ...base,
+  velocity,
+});
+
+/** True when the viewer has asked the OS to reduce motion. */
+export const prefersReducedMotion = () =>
+  typeof window !== 'undefined' &&
+  window.matchMedia('(prefers-reduced-motion: reduce)').matches;

src/lib/post-dates.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, it } from 'vitest';
+import { DatedValue, preferDate, shouldReplaceDate } from './post-dates';
+
+const sidecar: DatedValue = { date: '2024-04-07', source: 'sidecar' };
+const filename: DatedValue = { date: '2024-04-08', source: 'filename' };
+const mtime: DatedValue = { date: '2026-08-17', source: 'mtime' };
+
+describe('date precedence', () => {
+  it('ranks sidecar above filename above mtime', () => {
+    expect(preferDate(mtime, filename)).toEqual(filename);
+    expect(preferDate(filename, sidecar)).toEqual(sidecar);
+    expect(preferDate(mtime, sidecar)).toEqual(sidecar);
+  });
+
+  it('never lets a weaker source overwrite a stronger one', () => {
+    expect(preferDate(sidecar, filename)).toEqual(sidecar);
+    expect(preferDate(sidecar, mtime)).toEqual(sidecar);
+    expect(preferDate(filename, mtime)).toEqual(filename);
+  });
+
+  it('keeps the incumbent on a tie, so scan order cannot flip the date', () => {
+    const other: DatedValue = { date: '2020-01-01', source: 'filename' };
+    expect(preferDate(filename, other)).toEqual(filename);
+    expect(preferDate(other, filename)).toEqual(other);
+  });
+
+  it('accepts anything when nothing is held yet', () => {
+    expect(preferDate(undefined, mtime)).toEqual(mtime);
+    expect(shouldReplaceDate(undefined, mtime)).toBe(true);
+  });
+
+  it('ignores an empty date regardless of source', () => {
+    const empty: DatedValue = { date: '', source: 'sidecar' };
+    expect(shouldReplaceDate(filename, empty)).toBe(false);
+    expect(preferDate(filename, empty)).toEqual(filename);
+  });
+
+  it('replaces a held-but-empty date', () => {
+    const empty: DatedValue = { date: '', source: 'filename' };
+    expect(preferDate(empty, mtime)).toEqual(mtime);
+  });
+
+  it('is order-independent for the full three-source case', () => {
+    const orders = [
+      [mtime, filename, sidecar],
+      [sidecar, mtime, filename],
+      [filename, sidecar, mtime],
+      [mtime, sidecar, filename],
+    ];
+    for (const order of orders) {
+      const won = order.reduce<DatedValue | undefined>(
+        (acc, next) => preferDate(acc, next), undefined);
+      expect(won).toEqual(sidecar);
+    }
+  });
+});

src/lib/post-dates.ts

@@ -0,0 +1,46 @@
+/**
+ * Where a post's date came from, and which source wins.
+ *
+ * A post is usually described by several files — media, a caption `.txt`, a
+ * `.json` sidecar, sometimes the same item under two naming conventions — and
+ * they are scanned in directory order, not in order of trustworthiness. Without
+ * an explicit ranking the date is decided by whichever file happened to be
+ * reached first.
+ *
+ * Ranked best to worst:
+ *
+ *   sidecar   what Instagram reported, straight from a gallery-dl `.json`
+ *   filename  a date the fetcher wrote into the name; correct, but derived
+ *   mtime     when the file was written to disk — unrelated to when it was
+ *             posted, and only ever a last resort for JDownloader highlights,
+ *             whose filenames carry no date at all
+ */
+export type DateSource = 'sidecar' | 'filename' | 'mtime';
+
+const RANK: Record<DateSource, number> = { sidecar: 0, filename: 1, mtime: 2 };
+
+export interface DatedValue {
+  date: string;
+  source: DateSource;
+}
+
+/**
+ * Whether `next` should replace the date currently held.
+ *
+ * Ties keep the incumbent, so scanning stays stable: two files of equal
+ * authority cannot flip a post's date back and forth by scan order.
+ */
+export const shouldReplaceDate = (
+  current: DatedValue | undefined,
+  next: DatedValue,
+): boolean => {
+  if (!next.date) return false;
+  if (!current || !current.date) return true;
+  return RANK[next.source] < RANK[current.source];
+};
+
+/** Apply `next` if it outranks `current`, otherwise keep what we have. */
+export const preferDate = (
+  current: DatedValue | undefined,
+  next: DatedValue,
+): DatedValue => (shouldReplaceDate(current, next) ? next : (current ?? next));

src/lib/post-tabs.test.ts

@@ -0,0 +1,141 @@
+import { describe, expect, it } from 'vitest';
+import { dedupePostCopies, hasReelSource, makeIsReel, postsForTab } from './post-tabs';
+import { MediaFile, Post } from '../types';
+
+const media = (type: MediaFile['type'], index = 1): MediaFile => ({
+  name: `f${index}.${type === 'video' ? 'mp4' : 'jpg'}`,
+  path: `d/f${index}`, url: '', type, index,
+});
+
+const post = (id: string, opts: Partial<Post> = {}): Post => ({
+  id, date: '2024-01-01', username: 'u', caption: '', media: [media('image')], thumbnail: '', ...opts,
+});
+
+const video = (id: string, opts: Partial<Post> = {}) => post(id, { media: [media('video')], ...opts });
+const carousel = (id: string, opts: Partial<Post> = {}) =>
+  post(id, { media: [media('image', 1), media('video', 2)], ...opts });
+
+describe('hasReelSource', () => {
+  it('is false for an archive with no reels directory', () => {
+    expect(hasReelSource([post('A'), video('B')])).toBe(false);
+  });
+
+  it('is true once any post came from a reels directory', () => {
+    expect(hasReelSource([post('A'), video('u - reels/B', { source: 'reels' })])).toBe(true);
+  });
+});
+
+describe('makeIsReel', () => {
+  it('believes the reels directory when there is one', () => {
+    const posts = [video('A'), video('u - reels/B', { source: 'reels' })];
+    const isReel = makeIsReel(posts);
+    // A is a lone video too, but the archive states which posts are reels.
+    expect(isReel(posts[0])).toBe(false);
+    expect(isReel(posts[1])).toBe(true);
+  });
+
+  it('falls back to the lone-video heuristic without one', () => {
+    const posts = [post('A'), video('B'), carousel('C')];
+    const isReel = makeIsReel(posts);
+    expect(posts.map(isReel)).toEqual([false, true, false]);
+  });
+});
+
+describe('dedupePostCopies', () => {
+  it('leaves distinct posts alone', () => {
+    const posts = [post('A'), video('B')];
+    expect(dedupePostCopies(posts).map(p => p.id)).toEqual(['A', 'B']);
+  });
+
+  it('collapses a reel fetched into both the profile and the reels directory', () => {
+    const posts = [video('B'), video('u - reels/B', { source: 'reels' })];
+    const deduped = dedupePostCopies(posts);
+    expect(deduped).toHaveLength(1);
+    // The reels copy wins, so the survivor is still recognised as a reel.
+    expect(deduped[0].source).toBe('reels');
+  });
+
+  it('picks the reels copy regardless of scan order', () => {
+    const profileCopy = video('B');
+    const reelCopy = video('u - reels/B', { source: 'reels' });
+    expect(dedupePostCopies([profileCopy, reelCopy])[0].source).toBe('reels');
+    expect(dedupePostCopies([reelCopy, profileCopy])[0].source).toBe('reels');
+  });
+
+  it('keeps the position of the first copy seen', () => {
+    const posts = [post('A'), video('B'), post('C'), video('u - reels/B', { source: 'reels' })];
+    expect(dedupePostCopies(posts).map(p => p.id.split('/').pop())).toEqual(['A', 'B', 'C']);
+  });
+});
+
+describe('postsForTab', () => {
+  it('shows reels in the profile grid, as Instagram does', () => {
+    const posts = [post('A'), video('u - reels/B', { source: 'reels' })];
+    expect(postsForTab(posts, 'posts').map(p => p.id)).toEqual(['A', 'u - reels/B']);
+  });
+
+  it('shows the same reel in both tabs', () => {
+    const posts = [post('A'), video('u - reels/B', { source: 'reels' })];
+    const inGrid = postsForTab(posts, 'posts').map(p => p.id);
+    const inReels = postsForTab(posts, 'reels').map(p => p.id);
+    expect(inReels).toEqual(['u - reels/B']);
+    expect(inGrid).toContain('u - reels/B');
+  });
+
+  it('shows a duplicated reel once in the grid, not twice', () => {
+    const posts = [post('A'), video('B'), video('u - reels/B', { source: 'reels' })];
+    expect(postsForTab(posts, 'posts')).toHaveLength(2);
+    expect(postsForTab(posts, 'reels')).toHaveLength(1);
+  });
+
+  it('treats lone videos as reels for archives with no reels directory', () => {
+    const posts = [post('A'), video('B'), carousel('C')];
+    expect(postsForTab(posts, 'posts').map(p => p.id)).toEqual(['A', 'B', 'C']);
+    expect(postsForTab(posts, 'reels').map(p => p.id)).toEqual(['B']);
+  });
+
+  it('has nothing saved', () => {
+    expect(postsForTab([post('A')], 'saved')).toEqual([]);
+  });
+});
+
+/**
+ * Once an archive carries gallery-dl sidecars, the guesswork above is replaced
+ * by Instagram's own classification. These are the cases the heuristic got
+ * wrong (see docs/gallery-dl.md).
+ */
+describe('explicit isReel from a sidecar', () => {
+  it('beats the lone-video heuristic for an ordinary feed video', () => {
+    // A single mp4 that Instagram calls a post, not a reel — indistinguishable
+    // by shape alone.
+    const posts = [video('DbdG9L9jU4m', { isReel: false })];
+    expect(postsForTab(posts, 'reels')).toEqual([]);
+    expect(postsForTab(posts, 'posts')).toHaveLength(1);
+  });
+
+  it('recognises a reel that lives in the profile grid', () => {
+    // Shared to feed, so it sits in the base directory with source 'posts'.
+    const posts = [post('A'), video('C8FHM6EJl15', { source: 'posts', isReel: true })];
+    expect(postsForTab(posts, 'reels').map(p => p.id)).toEqual(['C8FHM6EJl15']);
+    expect(postsForTab(posts, 'posts')).toHaveLength(2);
+  });
+
+  it('beats the directory when both are present', () => {
+    const posts = [
+      video('u - reels/A', { source: 'reels', isReel: false }),
+      video('u - reels/B', { source: 'reels' }),
+    ];
+    // A is a feed video that the reels tab happened to return; B is unlabelled
+    // and falls back to its directory.
+    expect(postsForTab(posts, 'reels').map(p => p.id)).toEqual(['u - reels/B']);
+  });
+
+  it('falls back per post, so a mixed archive still works', () => {
+    const posts = [
+      video('labelled', { isReel: true }),
+      video('unlabelled'),
+      carousel('C'),
+    ];
+    expect(postsForTab(posts, 'reels').map(p => p.id)).toEqual(['labelled', 'unlabelled']);
+  });
+});

src/lib/post-tabs.ts

@@ -0,0 +1,108 @@
+import { Post, SourceKind } from '../types';
+import { Tab } from './routing';
+
+/**
+ * Which posts each profile tab shows.
+ *
+ * Instagram's profile grid holds everything the account posted — photos,
+ * carousels and reels alike — and the Reels tab is a *filtered view* of that
+ * same set rather than a separate one. So a reel belongs in both tabs, and
+ * only the Reels tab does any filtering.
+ *
+ * Kept pure and separate from App.tsx so the reel heuristic and the
+ * duplicate-copy rules can be tested directly.
+ */
+
+/**
+ * The shortcode shared by every copy of a post, regardless of which source
+ * directory it came from. Sidecar ids are directory-scoped
+ * (`4utumn07 - reels/Cq8LrxSJAJE`); the trailing segment is the shortcode.
+ */
+const shortcode = (post: Post): string => post.id.split('/').pop() ?? post.id;
+
+/**
+ * True when the archive has a `- reels` sidecar directory, i.e. it states
+ * outright which posts are reels.
+ */
+export const hasReelSource = (posts: Post[]): boolean => posts.some(p => p.source === 'reels');
+
+/**
+ * Build the reel test for an archive.
+ *
+ * Instagram's own marker is `product_type: "clips"` on the post's GraphQL
+ * node, but only Instaloader archives carry that metadata, and only on newer
+ * captures — JDownloader grabs are media plus a caption `.txt` and nothing
+ * else (see docs/jdownloader.md). So:
+ *
+ *   - archives with a `- reels` directory are believed outright;
+ *   - everything else falls back to treating a lone video as a reel.
+ *
+ * The fallback is a guess: it cannot tell a reel from an ordinary feed video
+ * or an old IGTV upload, all three of which are plain `GraphVideo` nodes
+ * distinguished only by `product_type`.
+ */
+export const makeIsReel = (posts: Post[]): ((post: Post) => boolean) => {
+  const guess = hasReelSource(posts)
+    ? (post: Post) => post.source === 'reels'
+    : (post: Post) => post.media.length === 1 && post.media[0]?.type === 'video';
+
+  // `isReel` comes from a gallery-dl sidecar and is Instagram's own answer, so
+  // it beats both fallbacks — per post, since an archive is usually a mix of
+  // files fetched before and after sidecars existed.
+  return (post: Post) => post.isReel ?? guess(post);
+};
+
+/** Preference order when the same post was fetched into more than one directory. */
+const SOURCE_RANK: Record<SourceKind, number> = { reels: 0, posts: 1, stories: 2, highlight: 3 };
+
+const rankOf = (post: Post): number => SOURCE_RANK[post.source ?? 'posts'];
+
+/**
+ * Collapse copies of one post that were fetched into more than one directory.
+ *
+ * The JDownloader flow crawls a profile URL and its `/reels/` URL separately
+ * because the profile page misses some reels — so the two overlap, and a reel
+ * present in both lands on disk twice. Those become two posts with distinct
+ * directory-scoped ids, which the grid would happily render side by side.
+ *
+ * The reels-source copy wins, so the surviving post still reports
+ * `source: 'reels'` and both the Reels tab and `tabForSource` recognise it.
+ *
+ * Only safe because callers pass the grid's posts, which exclude stories and
+ * highlights — a shortcode may legitimately appear in both the profile and a
+ * highlight, and those must stay distinct.
+ */
+export const dedupePostCopies = (posts: Post[]): Post[] => {
+  const winners = new Map<string, Post>();
+
+  for (const post of posts) {
+    const code = shortcode(post);
+    const existing = winners.get(code);
+    if (!existing || rankOf(post) < rankOf(existing)) winners.set(code, post);
+  }
+
+  // Preserve input order, keyed on the winner so ordering does not depend on
+  // which copy happened to be scanned first.
+  const emitted = new Set<string>();
+  const result: Post[] = [];
+  for (const post of posts) {
+    const code = shortcode(post);
+    if (emitted.has(code)) continue;
+    emitted.add(code);
+    result.push(winners.get(code)!);
+  }
+  return result;
+};
+
+/**
+ * The posts a tab displays.
+ *
+ * `posts` must already exclude stories and highlights (App passes `allPosts`).
+ */
+export const postsForTab = (posts: Post[], tab: Tab): Post[] => {
+  if (tab === 'saved') return [];
+
+  const unique = dedupePostCopies(posts);
+  if (tab === 'posts') return unique;
+  return unique.filter(makeIsReel(posts));
+};

src/lib/routing.test.ts

@@ -0,0 +1,114 @@
+import { describe, expect, it } from 'vitest';
+import { buildPath, findPostBySlug, parseRoute, postSlug, tabForSource } from './routing';
+import { Post } from '../types';
+
+const post = (id: string, source?: Post['source']): Post => ({
+  id, date: '2024-01-01', username: 'u', caption: '', media: [], thumbnail: '', source,
+});
+
+describe('parseRoute', () => {
+  it('reads the explorer root', () => {
+    expect(parseRoute('/')).toEqual({ archive: null, tab: 'posts', post: null });
+  });
+
+  it('reads a profile', () => {
+    expect(parseRoute('/4utumn07/')).toEqual({ archive: '4utumn07', tab: 'posts', post: null });
+  });
+
+  it('reads a profile without a trailing slash', () => {
+    expect(parseRoute('/4utumn07')).toEqual({ archive: '4utumn07', tab: 'posts', post: null });
+  });
+
+  it('reads a tab', () => {
+    expect(parseRoute('/4utumn07/reels/').tab).toBe('reels');
+    expect(parseRoute('/4utumn07/saved/').tab).toBe('saved');
+  });
+
+  it('reads a post in Instagram form', () => {
+    expect(parseRoute('/4utumn07/p/Db5tIoRCcvm/')).toEqual({
+      archive: '4utumn07', tab: 'posts', post: 'Db5tIoRCcvm',
+    });
+  });
+
+  it('decodes archive names containing spaces', () => {
+    expect(parseRoute('/Heejin_Bubble%20heejinmedia/').archive).toBe('Heejin_Bubble heejinmedia');
+  });
+
+  it('does not treat reserved prefixes as archives', () => {
+    for (const path of ['/api/archives', '/archives/x/y.jpg', '/assets/index.js']) {
+      expect(parseRoute(path).archive).toBeNull();
+    }
+  });
+
+  it('still understands the legacy query form', () => {
+    expect(parseRoute('/', '?a=4utumn07&t=reels&p=ABC')).toEqual({
+      archive: '4utumn07', tab: 'reels', post: 'ABC',
+    });
+  });
+
+  it('ignores an unknown tab', () => {
+    expect(parseRoute('/', '?a=u&t=bogus').tab).toBe('posts');
+  });
+});
+
+describe('buildPath', () => {
+  it.each([
+    [{ archive: null, tab: 'posts', post: null }, '/'],
+    [{ archive: '4utumn07', tab: 'posts', post: null }, '/4utumn07/'],
+    [{ archive: '4utumn07', tab: 'reels', post: null }, '/4utumn07/reels/'],
+    [{ archive: '4utumn07', tab: 'posts', post: 'Db5tIoRCcvm' }, '/4utumn07/p/Db5tIoRCcvm/'],
+  ] as const)('builds %j', (route, expected) => {
+    expect(buildPath(route as any)).toBe(expected);
+  });
+
+  it('omits the tab from a post URL, matching Instagram', () => {
+    expect(buildPath({ archive: 'u', tab: 'reels', post: 'ABC' })).toBe('/u/p/ABC/');
+  });
+
+  it('encodes archive names with spaces', () => {
+    expect(buildPath({ archive: 'a b', tab: 'posts', post: null })).toBe('/a%20b/');
+  });
+
+  it('round-trips through parseRoute', () => {
+    for (const route of [
+      { archive: '4utumn07', tab: 'posts' as const, post: null },
+      { archive: '4utumn07', tab: 'reels' as const, post: null },
+      { archive: 'Heejin_Bubble heejinmedia', tab: 'posts' as const, post: null },
+    ]) {
+      expect(parseRoute(buildPath(route))).toEqual(route);
+    }
+  });
+});
+
+describe('postSlug / findPostBySlug', () => {
+  it('uses the bare shortcode for base posts', () => {
+    expect(postSlug(post('Db5tIoRCcvm'))).toBe('Db5tIoRCcvm');
+  });
+
+  it('strips the sidecar directory from the slug', () => {
+    expect(postSlug(post('story highlights - u - Sunstory/C5dQPEYpd9W'))).toBe('C5dQPEYpd9W');
+  });
+
+  it('resolves a slug back to its post', () => {
+    const posts = [post('AAA'), post('4utumn07 - reels/BBB', 'reels')];
+    expect(findPostBySlug(posts, 'BBB')?.id).toBe('4utumn07 - reels/BBB');
+    expect(findPostBySlug(posts, 'AAA')?.id).toBe('AAA');
+  });
+
+  it('prefers an exact id match over a shortcode match', () => {
+    const posts = [post('x/ABC'), post('ABC')];
+    expect(findPostBySlug(posts, 'ABC')?.id).toBe('ABC');
+  });
+
+  it('returns undefined for an unknown slug', () => {
+    expect(findPostBySlug([post('AAA')], 'ZZZ')).toBeUndefined();
+  });
+});
+
+describe('tabForSource', () => {
+  it('sends reels to the reels tab and everything else to posts', () => {
+    expect(tabForSource('reels')).toBe('reels');
+    expect(tabForSource('posts')).toBe('posts');
+    expect(tabForSource(undefined)).toBe('posts');
+  });
+});

src/lib/routing.ts

@@ -0,0 +1,85 @@
+import { Post, SourceKind } from '../types';
+
+/**
+ * Instagram-shaped paths.
+ *
+ *   /                          the archive explorer
+ *   /<archive>/                a profile, posts tab
+ *   /<archive>/reels/          a profile, reels tab
+ *   /<archive>/saved/
+ *   /<archive>/p/<shortcode>/  a single post
+ *
+ * The older `?a=&t=&p=` query form is still parsed so existing links keep
+ * working; it is never written back.
+ */
+
+export type Tab = 'posts' | 'reels' | 'saved';
+
+const TABS: Tab[] = ['posts', 'reels', 'saved'];
+
+/**
+ * Path prefixes the app must never treat as an archive name, or a profile
+ * called "api" would shadow the backend.
+ */
+const RESERVED = new Set(['api', 'archives', 'assets', 'p', 'fonts', 'sw.js', 'manifest.webmanifest']);
+
+export interface Route {
+  archive: string | null;
+  tab: Tab;
+  /** Post shortcode, i.e. the trailing segment of a post id. */
+  post: string | null;
+}
+
+/**
+ * A post's URL slug.
+ *
+ * Sidecar posts carry a directory-scoped id (`story highlights - u - H/ABC`)
+ * so ids stay unique across sources, but only the shortcode belongs in a URL.
+ */
+export const postSlug = (post: Pick<Post, 'id'>): string => {
+  const tail = post.id.split('/').pop() ?? post.id;
+  return encodeURIComponent(tail);
+};
+
+/** Find the post a slug refers to, preferring an exact id match. */
+export const findPostBySlug = (posts: Post[], slug: string): Post | undefined => {
+  const decoded = decodeURIComponent(slug);
+  return posts.find(p => p.id === decoded)
+    ?? posts.find(p => (p.id.split('/').pop() ?? p.id) === decoded);
+};
+
+/** Which tab shows a given post, so a deep link lands on the right one. */
+export const tabForSource = (source?: SourceKind): Tab => (source === 'reels' ? 'reels' : 'posts');
+
+export const parseRoute = (pathname: string, search = ''): Route => {
+  const segments = pathname.split('/').filter(Boolean).map(decodeURIComponent);
+
+  if (segments.length && !RESERVED.has(segments[0])) {
+    const [archive, second, third] = segments;
+
+    if (second === 'p' && third) return { archive, tab: 'posts', post: third };
+    if (second && TABS.includes(second as Tab)) return { archive, tab: second as Tab, post: null };
+    return { archive, tab: 'posts', post: null };
+  }
+
+  // Legacy query form: ?a=<archive>&t=<tab>&p=<post id>
+  const params = new URLSearchParams(search);
+  const archive = params.get('a');
+  const tab = params.get('t');
+  return {
+    archive: archive || null,
+    tab: tab && TABS.includes(tab as Tab) ? (tab as Tab) : 'posts',
+    post: params.get('p'),
+  };
+};
+
+export const buildPath = ({ archive, tab, post }: Route): string => {
+  if (!archive) return '/';
+
+  const base = `/${encodeURIComponent(archive)}`;
+  // A post URL omits the tab, matching Instagram; the tab is re-derived from
+  // the post itself when the link is opened.
+  if (post) return `${base}/p/${post}/`;
+  if (tab !== 'posts') return `${base}/${tab}/`;
+  return `${base}/`;
+};

src/lib/thumbnail-worker.ts

@@ -0,0 +1,42 @@
+/**
+ * Thumbnail Generation Worker
+ * Uses OffscreenCanvas and createImageBitmap for high-performance,
+ * background-thread image resizing.
+ */
+
+self.onmessage = async (e: MessageEvent) => {
+  const { id, blob, width } = e.data;
+
+  try {
+    // 1. Create a bitmap from the blob (native browser decoding)
+    // We resize it DURING the decode step for maximum efficiency
+    const bitmap = await createImageBitmap(blob, {
+      resizeWidth: width,
+      resizeQuality: 'medium'
+    });
+
+    // 2. Use OffscreenCanvas to draw the resized bitmap
+    const canvas = new OffscreenCanvas(bitmap.width, bitmap.height);
+    const ctx = canvas.getContext('2d');
+    
+    if (!ctx) {
+      throw new Error('Could not get OffscreenCanvas context');
+    }
+
+    ctx.drawImage(bitmap, 0, 0);
+    
+    // 3. Convert to a small JPEG blob
+    const thumbnailBlob = await canvas.convertToBlob({
+      type: 'image/jpeg',
+      quality: 0.7
+    });
+
+    // 4. Release bitmap memory
+    bitmap.close();
+
+    // 5. Send result back
+    self.postMessage({ id, blob: thumbnailBlob });
+  } catch (err: any) {
+    self.postMessage({ id, error: err.message });
+  }
+};

src/lib/utils.ts

@@ -0,0 +1,26 @@
+import { clsx, type ClassValue } from 'clsx';
+import { twMerge } from 'tailwind-merge';
+import { format, parseISO } from 'date-fns';
+
+export function cn(...inputs: ClassValue[]) {
+  return twMerge(clsx(inputs));
+}
+
+/**
+ * Format an archive date, tolerating junk.
+ *
+ * Dates are derived from filenames and arbitrary archive JSON, and date-fns
+ * `format` throws a RangeError on an invalid date — which would take down the
+ * whole modal for one malformed name. Story highlights in particular carry no
+ * date at all when file mtimes are unavailable.
+ */
+export function formatDateSafe(date: string | undefined, pattern: string): string {
+  if (!date) return '';
+  try {
+    const parsed = parseISO(date);
+    if (Number.isNaN(parsed.getTime())) return '';
+    return format(parsed, pattern);
+  } catch {
+    return '';
+  }
+}

src/main.tsx

@@ -1,13 +1,34 @@
 import {StrictMode} from 'react';
 import {createRoot} from 'react-dom/client';
 import App from './App.tsx';
+import { ErrorBoundary } from './components/ErrorBoundary';
 import './index.css';
 import { registerSW } from 'virtual:pwa-register';
 
-registerSW();
+// Register service worker with automatic updates
+// and a periodic check every hour to ensure long-running sessions stay fresh.
+const updateSW = registerSW({
+  onRegistered(r) {
+    if (r) {
+      // Check for updates every hour
+      setInterval(() => {
+        r.update();
+      }, 60 * 60 * 1000);
+      console.log(`[PWA] v${__APP_VERSION__} registered; hourly update checks enabled.`);
+    }
+  },
+  onNeedRefresh() {
+    console.log('[PWA] New content available, reloading...');
+  },
+  onOfflineReady() {
+    console.log('[PWA] App is ready for offline use.');
+  }
+});
 
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
+    <ErrorBoundary>
       <App />
+    </ErrorBoundary>
   </StrictMode>,
 );

src/types/globals.d.ts

@@ -0,0 +1,9 @@
+/**
+ * Build-time constants.
+ *
+ * This file deliberately has no imports or exports: that keeps it an ambient
+ * script rather than a module, so the declarations below are global.
+ */
+
+/** Release version, injected by `define` in vite.config.ts. */
+declare const __APP_VERSION__: string;

src/types/index.ts

@@ -0,0 +1,129 @@
+export interface MediaFile {
+  name: string;
+  /**
+   * Path relative to the archive root (matching webkitRelativePath for local
+   * folders). Unlike `url`, this survives a page reload, so it is what the
+   * cache persists and what URLs are rehydrated from.
+   */
+  path: string;
+  url: string;
+  type: 'image' | 'video';
+  index: number;
+  size?: number;
+}
+
+/**
+ * Which sidecar directory a post came from. Archives store reels, stories and
+ * each story highlight in directories alongside the base profile; the viewer
+ * folds them into one profile and routes them by kind.
+ */
+export type SourceKind = 'posts' | 'reels' | 'stories' | 'highlight';
+
+export interface ArchiveSource {
+  kind: SourceKind;
+  /** Directory name relative to the archives root. */
+  dir: string;
+  /** Highlight title, for kind === 'highlight'. */
+  title?: string;
+}
+
+export interface Post {
+  id: string;
+  date: string;
+  username: string;
+  caption: string;
+  media: MediaFile[];
+  thumbnail: string;
+  isStory?: boolean;
+  /** Defaults to 'posts' for archives without sidecar directories. */
+  source?: SourceKind;
+  /**
+   * Instagram's own answer to "is this a reel", from a gallery-dl `.json`
+   * sidecar. Undefined when the archive carries no such sidecar, which is when
+   * the viewer has to fall back to guessing — see src/lib/post-tabs.ts.
+   */
+  isReel?: boolean;
+  /** Highlight this post belongs to, for source === 'highlight'. */
+  highlightTitle?: string;
+}
+
+/**
+ * Common interface for both local File objects and remote server-side files.
+ */
+export interface ArchiveFile {
+  name: string;
+  webkitRelativePath: string;
+  size: number;
+  text(): Promise<string>;
+  arrayBuffer(): Promise<ArrayBuffer>;
+  url?: string;
+  /**
+   * A URL pointing at this file's contents. Local files mint a disk-backed
+   * blob: URL (no data is read into memory); remote files return their HTTP URL.
+   */
+  createObjectUrl(mimeHint?: string): string;
+  /** True when createObjectUrl() returns a blob: URL that must be revoked. */
+  readonly revocable: boolean;
+  /** Which sidecar directory this file came from, when known. */
+  source?: ArchiveSource;
+  /** Last-modified time (ms). Used to date items whose filename has no date. */
+  mtime?: number;
+}
+
+export interface ServerArchive {
+  name: string;
+  thumbnail: string;
+  path: string;
+  /** Null until the server has indexed this profile. */
+  fileCount: number | null;
+  /**
+   * Directory-mtime signature. Cheap for the server to compute and sufficient
+   * to detect changes, unlike a file count that would require a full walk.
+   */
+  signature?: string;
+  /** Base profile plus any sidecar directories folded into it. */
+  sources?: ArchiveSource[];
+}
+
+/** One entry from GET /api/archives/:name/files. */
+export interface ServerArchiveFile {
+  path: string;
+  size: number;
+  mtime: number;
+  kind: SourceKind;
+  title?: string;
+}
+
+export interface ProfileMetadata {
+  username: string;
+  fullName: string;
+  bio: string;
+  followerCount: number;
+  followingCount: number;
+  externalUrl: string;
+  profilePic: string | null;
+  allProfilePics: string[];
+}
+
+/** Shape of an archive entry persisted in IndexedDB. */
+export interface CacheData {
+  name: string;
+  isLocal: boolean;
+  fileCount: number;
+  /** Server archives: the signature this entry was built from. */
+  signature?: string;
+  posts: Post[];
+  stories: Post[];
+  /** Story-highlight items, grouped by `highlightTitle`. */
+  highlights?: Post[];
+  profileMetadata: ProfileMetadata;
+  timestamp: number;
+  /**
+   * Local archives only: whether a FileSystemDirectoryHandle was stored
+   * alongside this entry, meaning media URLs can be rehydrated without
+   * re-prompting for the folder.
+   */
+  hasDirectoryHandle?: boolean;
+  /** Path of the profile picture, for rehydration (local archives). */
+  profilePicPath?: string;
+}

src/types/react-augment.d.ts

@@ -0,0 +1,12 @@
+import 'react';
+
+declare module 'react' {
+  interface InputHTMLAttributes<T> {
+    /**
+     * Non-standard attribute that makes a file input select a whole directory.
+     * Supported in Chromium and WebKit; used as the fallback picker where the
+     * File System Access API is unavailable.
+     */
+    webkitdirectory?: string;
+  }
+}

vite.config.ts

@@ -1,17 +1,31 @@
 import tailwindcss from '@tailwindcss/vite';
 import react from '@vitejs/plugin-react';
 import path from 'path';
-import {defineConfig, loadEnv} from 'vite';
+import {defineConfig} from 'vite';
 import { VitePWA } from 'vite-plugin-pwa';
+import { createRequire } from 'module';
 
-export default defineConfig(({mode}) => {
-  const env = loadEnv(mode, '.', '');
+const { version } = createRequire(import.meta.url)('./package.json');
+
+export default defineConfig(() => {
   return {
+    /**
+     * The release version, compiled into the client.
+     *
+     * This is load-bearing, not cosmetic. The service worker precaches
+     * index.html *including its response headers*, so a server-side header
+     * change (a CSP fix, say) never reaches an installed PWA: nothing in the
+     * client build changed, the precache manifest is byte-identical, and the
+     * worker has no reason to update. Baking the version in means every release
+     * changes the bundle hash, which changes index.html, which invalidates the
+     * precache and re-fetches the shell with current headers.
+     */
+    define: { __APP_VERSION__: JSON.stringify(version) },
     plugins: [
       react(), 
       tailwindcss(),
       VitePWA({
-        registerType: 'prompt',
+        registerType: 'autoUpdate',
         manifest: {
           name: 'InstaArchive',
           short_name: 'InstaArchive',
@@ -21,42 +35,26 @@ export default defineConfig(({mode}) => {
           display: 'standalone',
           icons: [
             {
-              src: 'https://cdn-icons-png.flaticon.com/512/174/174855.png',
+              src: '/icon-512.png',
               sizes: '512x512',
               type: 'image/png',
               purpose: 'any maskable'
             },
             {
-              src: 'https://cdn-icons-png.flaticon.com/192/174/174855.png',
+              src: '/icon-192.png',
               sizes: '192x192',
               type: 'image/png'
             }
           ]
         },
         workbox: {
-          globPatterns: ['**/*.{js,css,html,ico,png,svg,woff,woff2}'],
-          runtimeCaching: [
-            {
-              urlPattern: /^https:\/\/fonts\.googleapis\.com\/.*/i,
-              handler: 'CacheFirst',
-              options: {
-                cacheName: 'google-fonts-cache',
-                expiration: {
-                  maxEntries: 10,
-                  maxAgeSeconds: 60 * 60 * 24 * 365
-                },
-                cacheableResponse: {
-                  statuses: [0, 200]
-                }
-              }
-            }
-          ]
+          navigateFallbackDenylist: [/^\/api/, /^\/archives/],
+          // Fonts and icons are bundled locally, so everything the shell needs
+          // is precached and no runtime third-party caching rule is required.
+          globPatterns: ['**/*.{js,css,html,ico,png,svg,woff,woff2}']
         }
       })
     ],
-    define: {
-      'process.env.GEMINI_API_KEY': JSON.stringify(env.GEMINI_API_KEY),
-    },
     resolve: {
       alias: {
         '@': path.resolve(__dirname, '.'),