feat: add browser-based sender and receiver (qrl_web)

.gitignore

@@ -142,4 +142,7 @@ Tempqrl_boxsize_test/
 Tempqrl_test_folder/
 Tempqrl_test_grid/
 Tempqrl_test_out/
-Tempqrl_test_single/
+Tempqrl_test_single/
+
+# claude
+.claude/

README.md

@@ -1,76 +1,126 @@
 # QRL — QR Link
 
-QRL transfers files across a screen boundary by encoding them as a flashing sequence of QR codes. The **server** chunks, compresses, and displays the codes; the **client** screen-captures and reassembles them into the original file.
+QRL transfers files across a screen boundary by encoding them as a sequence of QR codes. The **web sender** encodes, chunks, and displays the codes in the browser; the **receiver** scans and reassembles — either via the web receiver (camera) or the Python client (screen capture).
 
 No network connection, no clipboard, and no agent is needed on the receiving end — only a screen you can see. Typical scenarios: pulling a file out of a remote desktop session, VNC, Citrix, or any environment where the only shared channel is a rendered screen.
 
 ---
 
-## Quick start
+## Web version (recommended — no install)
 
-**Combined GUI — send and receive in one window:**
+`qrl_web/` is a browser-only implementation. Both sender and receiver run entirely in the browser — no Python, no build step.
+
+**Live on GitHub Pages:**
+
+| Page | URL |
+|------|-----|
+| Home | https://minimike86.github.io/QRL/qrl_web |
+| Sender | https://minimike86.github.io/QRL/qrl_web/sender.html |
+| Receiver | https://minimike86.github.io/QRL/qrl_web/receiver.html |
+
+**Or serve locally:**
 ```bash
-python qrl_gui.py
+cd qrl_web
+python -m http.server 8765
+# open http://localhost:8765
 ```
 
-**Standalone GUIs:**
+The receiver requires HTTPS or `localhost` for camera access — GitHub Pages and the local server both satisfy this.
+
+### Workflow
+
+1. Open **Sender** on the source device and select a file or folder.
+2. Configure settings (chunk size, FPS, error correction, QR size, fountain mode).
+3. Press **Start Transfer** — a manifest QR appears first. Press **Resume** once the receiver is ready.
+4. Open **Receiver** on the destination device and press **Start Camera**.
+5. Point the camera at the sender's screen. The file downloads automatically when all chunks arrive.
+
+### Sender settings
+
+| Setting | Default | Description |
+|---------|---------|-------------|
+| Chunk size (B) | 600 | Payload bytes per QR frame. Smaller = more reliable; larger = fewer total frames. |
+| FPS | 3 | Target frames per second. Increase in good lighting conditions. |
+| Error correction | L | Reed-Solomon redundancy baked into each QR (L / M / Q / H). |
+| QR size (px) | 420 | Rendered canvas size. Larger aids scanning from a distance. |
+| Frames per chunk | 1 | Hold each chunk for N consecutive frames before advancing (sequential mode only). |
+| Fountain mode | off | XOR-coded infinite packet stream — no replay needed (see below). |
+
+### Fountain mode
+
+When **Fountain mode** is on the sender generates an infinite stream of XOR-coded packets using LT codes. The receiver reconstructs the full file from any sufficient subset of packets via belief propagation — scanning can be intermittent without requiring a manual replay step.
+
+The sender display shows `fountain pkt N` (packet counter), **CYCLES** (completed equivalent-sets), and a cycling progress bar showing position within the current cycle.
+
+In sequential mode, the **Replay missing chunks** field lets you send only specific chunk numbers again by entering numbers, ranges, or comparisons (e.g. `3,7,5-10,>=50`).
+
+---
+
+## Python client (receive only)
+
+The Python client captures the screen with `mss` and decodes QR codes with `pyzbar`. It is fully compatible with the web sender — same wire format, same manifest, same fountain protocol.
+
+**GUI:**
 ```bash
-python -m qrl_server --gui   # encode and display
-python -m qrl_client --gui   # capture and decode
+python qrl_gui.py
+# or
+python -m qrl_client --gui
 ```
 
 **CLI:**
 ```bash
-qrl-server myfile.bin                          # display with defaults
-qrl-server myfile.bin --chunk-size 1490 --duration 0.1 --error-correction Q
-qrl-client --output /tmp/received/             # capture to folder
+qrl-client --output ~/received/
 ```
 
 ---
 
 ## How it works
 
-1. The server reads the source file (or tar-packs a folder), optionally gzips it, and splits it into fixed-size chunks.
-2. Each chunk gets a 9-byte binary header and is rendered as a QR code.
-3. A **manifest QR** is shown at the start of every display cycle carrying the filename, size, and stream metadata so a late-joining client can catch up.
-4. The client captures the screen on a configurable interval, decodes every visible QR per frame, and writes the file when the last chunk arrives.
+1. The sender reads the source file (or zip-packs a folder), optionally gzips it, and splits it into fixed-size chunks.
+2. Each chunk gets a 9-byte binary wire header and is encoded as a QR code in byte mode.
+3. A **manifest QR** (stream_id = 255) is shown first, carrying the filename, size, chunk count, and transfer mode so a late-joining receiver can catch up.
+4. **Sequential mode**: chunks cycle continuously until stopped. The receiver collects until the full set arrives, then auto-downloads.
+5. **Fountain mode**: an infinite stream of XOR-coded packets (stream_id = 2) is generated. The receiver runs iterative belief-propagation decoding and finalises as soon as all source chunks are recovered.
+6. The receiver decompresses and saves the file on completion.
 
-See [docs/architecture.md](docs/architecture.md) for the full wire format and data flow.
+See [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md) for the full wire format, fountain coding details, and data flow.
 
 ---
 
-## Features at a glance
+## Features
 
 | Area | Feature |
 |------|---------|
-| Encoding | Auto gzip compression (skipped if it doesn't help) |
-| Encoding | Folder support — tar-packed, auto-extracted on arrival |
-| Display | Configurable FPS (2 / 10 / 20 / 30) and QR quality presets |
-| Display | Parallel grid mode — 4, 9, 16, or auto-fit streams for multiplied throughput |
-| Display | Background prefetch with a bounded LRU cache |
-| Display | Export QR sequence as PDF or MP4 for offline replay |
-| GUI | Drag-and-drop file loading (server tab) |
-| Capture | Whole screen, specific monitor, or hand-drawn region |
-| Capture | Live preview at 5 fps while decoding runs |
-| Capture | Partial-progress save — resume an interrupted session |
-| Config | YAML / JSON config files with auto-discovery search paths |
+| **Web sender** | Browser-only — no install, no Python |
+| **Web sender** | Fountain mode: LT-code XOR packets, infinite stream, no replay needed |
+| **Web sender** | Sequential mode with targeted missing-chunk replay |
+| **Web sender** | Auto gzip compression (skipped when not beneficial) |
+| **Web sender** | Folder support — packed as .zip, extracted on arrival |
+| **Web sender** | Responsive two-column desktop layout and mobile-optimised UI |
+| **Web sender** | Contextual setting hints and QR flash animation |
+| **Web receiver** | Webcam-based scanning, chunk map, ETA, duplicate detection |
+| **Web receiver** | Auto-download on completion |
+| **Python client** | Screen capture via `mss` — no GUI required on remote end |
+| **Python client** | Whole screen, specific monitor, or hand-drawn capture region |
+| **Python client** | Live preview, partial-progress resume |
+| Config | YAML / JSON config files for the Python client |
 
 ---
 
 ## Documentation
 
 | File | Contents |
 |------|---------|
-| [docs/architecture.md](docs/architecture.md) | Wire format, data flow, compression, LRU cache, manifest |
-| [docs/server.md](docs/server.md) | All server settings, speed/quality/density/mode presets, export |
-| [docs/client.md](docs/client.md) | All client settings, region picker, monitor selection, progress |
-| [docs/parallel-streams.md](docs/parallel-streams.md) | How parallel grid mode works, throughput estimates |
-| [docs/configuration.md](docs/configuration.md) | Full config file reference and search path order |
-| [docs/cli.md](docs/cli.md) | All CLI flags for `qrl-server` and `qrl-client` |
+| [qrl_web/](qrl_web/) | Browser sender + receiver source |
+| [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md) | Wire format, fountain coding, data flow, compression |
+| [docs/server.md](docs/server.md) | Web sender settings, workflow, and display panel |
+| [docs/client.md](docs/client.md) | Python client settings, region picker, progress panel |
+| [docs/configuration.md](docs/configuration.md) | Python client config file reference and search paths |
+| [docs/cli.md](docs/cli.md) | `qrl-client` CLI flags |
 
 ---
 
-## Installation
+## Installation (Python client)
 
 ```bash
 git clone https://github.com/minimike86/QRL.git
@@ -92,5 +142,7 @@ pytest tests/
 
 ## Similar projects
 
-- [QRxfil](https://github.com/OverkillGuy/qrxfil) — QR-code-based file transfer, outputs a static PDF.
-- [QRExfil](https://github.com/Shell-Company/QRExfil) — QR code transfer with animated GIF output.
+- [txqr](https://github.com/divan/txqr)
+- [QRxfil](https://github.com/OverkillGuy/qrxfil) 
+- [QRExfil](https://github.com/Shell-Company/QRExfil)
+- [qrterminal](https://github.com/mdp/qrterminal)