util/crc32.hpp — header-only CRC-32 (zlib polynomial, reflected), used to integrity-check the sidecar. meta/veloxpart — the <name>.veloxpart.meta resume file (docs/04 §5). Little-endian, versioned, CRC-32 over the whole record. Layout: magic, version, flags, total_size, downloaded, url set (original/effective/ mirrors), etag/last-modified/content-type, segment records (start, end INCLUSIVE, completed), optional sha256 streaming-hash blob. parse_veloxpart() is the attacker-facing surface (the file sits in a world-writable-ish download dir) and is total on any byte string: CRC checked before any field is interpreted; magic, a version it understands, every count and length bounded by a hard cap AND checked against the remaining buffer; ByteReader latches on overrun; trailing bytes rejected. Every malformation is meta_corrupt / meta_version_unsupported, never a crash or an unbounded allocation. serialize_veloxpart() is deterministic (unchanged sidecar isn't rewritten). File helpers write atomically (temp + rename) and fdatasync the file and its directory. Tests: crc32 known vector; full + minimal round-trips; deterministic serialize; file round-trip; and a truncation/corruption table — bad magic, CRC mismatch (payload and CRC-field flips), future version, truncation at every stage, hostile url_count / segment_count / lp_string length (the case the brief singles out), trailing bytes, impossible segment.completed. tools/fuzz/fuzz_veloxpart — feeds raw bytes and bytes-with-valid-CRC (so the field parser and ByteReader bounds checks are actually reached), and round-trip-stability-checks anything accepted. Ran 1.1M execs clean under ASan+UBSan+libFuzzer (clang++-21); fuzz_content_disposition and fuzz_url likewise re-run to 1.1M. tools/fuzz gains a -runs=0 seed-replay CTest smoke per target (regression tripwire; the campaign stays manual). Fuzz-found and fixed: parse_content_disposition could emit a filename containing NUL / control bytes from a mangled filename* ext-value — strip_path only removed path separators. Now sanitize_leaf() also drops C0 controls and DEL (rules/ still owns the authoritative sanitize; `..` and printable-unsafe content pass through as before). Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01HPPSGhiArbvQgwC2DNiURS
Velox Download Manager (VDM)
An IDM-class download manager for Ubuntu 26.04 LTS: multi-segment accelerated HTTP(S) downloading, resume, categories and automatic file distribution, queues and scheduler, speed limiter, a Firefox extension that captures downloads automatically, and clipboard link capture.
Name is a placeholder. Binaries are
veloxd,velox-gui,velox,velox-nmhost. Rename before first release if you want something else — do it in M0, never later.
Status
Phase M0 — scaffolding. No implementation code exists yet. This repository currently contains the architecture, the wire contract, the roadmap, and one brief per build lane so that several agents can work in parallel without colliding.
Start here:
| Document | What it answers |
|---|---|
| docs/01-architecture.md | Process model, why four binaries, framework choices and why |
| docs/02-roadmap.md | Milestones M0–M7, what runs in parallel, exit gates |
| docs/03-gui-spec.md | IDM-parity UI: every window, dialog, column, menu |
| docs/04-engine-design.md | Segmentation, resume, buffers, rate limiting, disk I/O |
| docs/05-extension-spec.md | Firefox capture, transports, pairing, media grabber |
| docs/06-risks-and-spikes.md | Snap Firefox, Wayland clipboard, and the other landmines |
| docs/07-packaging.md | .deb/PPA, Flatpak, AMO signing, install layout |
| contracts/README.md | The interface. Both sides build against this |
| CLAUDE.md | Rules of engagement for agents working in this repo |
Per-lane briefs live in docs/agents/ — one per agent, each with an owned directory list, a definition of done, and the files it must never touch. To dispatch the agents, use docs/agents/PROMPTS.md — six copy-paste prompts plus the worktree commands and the wave order.
Architecture in one picture
┌────────────────────┐ native messaging (stdio JSON) ┌──────────────┐
│ Firefox extension │◄───────────── or ──────────────►│ velox-nmhost │
│ (MV3, TS) │ loopback WS 127.0.0.1 + token └──────┬───────┘
└────────────────────┘ │
│
┌────────────────────┐ ▼
│ velox-gui (Qt 6) │◄──── JSON-RPC 2.0 over Unix socket ──► ┌─────────────┐
└────────────────────┘ $XDG_RUNTIME_DIR/velox/velox.sock │ veloxd │
│ (daemon) │
┌────────────────────┐ │ │
│ velox (CLI) │◄───────────────────────────────────────┤ libveloxcore│
└────────────────────┘ └──────┬──────┘
│
SQLite + sparse files
The daemon owns all state and all sockets. The GUI is a view — closing it does not stop a download. The extension never touches the disk; it hands URL + headers + cookies to the daemon and gets a task id back.
Repository layout
vdm/
├── contracts/ ⭐ Wire contract: JSON Schema, fixtures, codegen. Frozen per version.
├── core/ C++23 libveloxcore — engine. No UI, no RPC, no SQL.
├── daemon/ C++23 veloxd — RPC server, scheduler, queues, SQLite store.
├── gui/ C++23 velox-gui — Qt 6 Widgets, IDM-parity UI.
├── cli/ C++23 velox — scriptable client.
├── nmhost/ C++23 velox-nmhost — Firefox native-messaging bridge (thin pipe).
├── extension/ TS Firefox MV3 WebExtension.
├── tools/
│ ├── mockd/ TS mock daemon — lets GUI + extension work before veloxd exists.
│ ├── testserver/ Deliberately hostile HTTP server (no Range, flaky, redirects, auth).
│ ├── bench/ Throughput and CPU benchmarks.
│ └── fuzz/ libFuzzer targets for parsers.
├── tests/
│ ├── conformance/ Protocol suite. Every lane must pass it. Gate for merging.
│ ├── integration/ veloxd + testserver.
│ └── e2e/ Playwright: real Firefox + real daemon + real file on disk.
├── packaging/ debian/, flatpak/, appimage/, native-host manifests.
└── docs/ Everything above, plus adr/ and agents/.
Toolchain bootstrap
Surveyed on this machine 2026-09-09 — most of it is already installed:
| Present | Version |
|---|---|
| git · cmake · ninja · g++ · gdb | 2.53.0 · 4.2.3 · — · 15.2.0 (C++23 ready) |
| qt6-base-dev · qt6-tools-dev · qt6-tools-dev-tools | ✓ |
| libcurl4-openssl-dev · libsqlite3-dev · nlohmann-json3-dev · libssl-dev | ✓ |
| libavformat-dev · libavcodec-dev · ffmpeg | ✓ |
| clang-format · clang-tidy · python3 · pkg-config | ✓ |
| python3-jsonschema · python3-referencing (conformance static runner) | ✓ |
Only these four are missing:
sudo apt update && sudo apt install -y \
libqt6svg6-dev \ # GUI: SVG icon rendering
libsecret-1-dev \ # DAEMON: Secret Service for site logins
nodejs npm \ # EXT + PROTO: extension build, mockd, conformance runner
clang # optional: libFuzzer targets in M7
Node in the 26.04 archive may lag; if the extension toolchain needs 22+, use nvm.
Verify with cmake --preset dev && cmake --build --preset dev once lane CORE lands its
first target. Note CMake 4.2.3 is installed — newer than the 3.28 floor in
CMakeLists.txt, and it hard-errors on cmake_minimum_required below 3.5, so no
dependency may ship a pre-3.5 CMake file.