What is BitTorrent, and how is it wired into Fushi?

What BT is ​

A normal download is "one server sends, you receive". BT (BitTorrent) flips it: there is no server — everyone currently downloading the file sends to everyone else. Every piece you receive can be passed on immediately; you take a little from dozens of people and assemble the whole file.

A few terms:

• Torrent (.torrent) / magnet link (magnet:): not the file itself but its "ID card" — filename, size, a checksum for every piece. With it you can find the people who hold the file. A magnet link squeezes that information into one line of text, easier to pass around than a .torrent file.
• Seeding: staying online after finishing and continuing to send. More seeders = faster; an old release with 0 seeders won't move.
• Leeching / share ratio: downloading without uploading is leeching; share ratio = uploaded ÷ downloaded. BT only lives on mutual uploading.
• Tracker: the "phone book" server that helps you find peers; DHT is the tracker-less way peers ask each other — with both on you find the most people.
• Index site: a website listing which torrents exist without storing the files. The biggest for anime is Nyaa; films and series have various public indexes; Torznab is a unified index API that tools like Jackett / Prowlarr translate hundreds of index sites into.
• Port mapping (UPnP / NAT-PMP): lets the router forward incoming connections to you so others can connect to you directly; downloading works without it, just slower.
• IPv6: the newer addressing scheme. On IPv4 most people sit behind a router and can't reach each other without port mapping; on IPv6 every device has a public address and seeders connect directly — turning IPv6 on usually finds a whole extra crowd of seeders.

BT itself is only a transport protocol; what's transported is a separate matter — it's the same thing whether you fetch a Linux image or an anime episode.

What Fushi integrates ​

You don't need a separate download client; the whole chain lives in the app:

How to use it ​

Built-in engine: nothing to configure ​

Bottom bar Browse → Discover: find the work, press Search resources on its page and download a release — it's queued (progress under Browse → Downloads). The first time you're asked whether to enable uploading / seeding — off by default; on, it uses your upload bandwidth but is kinder to the swarm.

• Play while downloading: once a task starts it can be shelved and opened from the video library.
• Have a magnet link or .torrent file? Add task at the top right of Browse → Downloads — paste the magnet link or "Choose torrent file"; on desktop you can also drag a .torrent onto the window.
• Task details show peers, tracker status and seeding time.

Details of use (raw filter, Trusted only, batches, subscriptions): Stream anime or download it?

External qBittorrent ​

If you already have an always-on machine running qBittorrent (typical for a NAS) and want it to do the downloading:

Settings → Downloads → Engine & seeding, set the download engine to External qBittorrent, enter the qBittorrent WebUI address (e.g. http://192.168.1.10:8080), username and password, and optionally a qBittorrent category (Fushi's tasks are tagged with it so you can tell them apart in qB).

When qBittorrent runs on another machine, the paths it sees differ from this device's, so configure qBittorrent path mappings: map qB's download root (say /downloads) to a location this device can reach (\\nas\downloads or a mounted drive) so Fushi can find the files and shelve them when done.

Search results also offer Push download to hand a task to qB directly; the rest of the flow is identical.

Engine & seeding settings ​

All under Settings → Downloads → Engine & seeding:

• Uploading / seeding: switch, upload limit, share-ratio limit, seeding-time limit — turn it on to give back; it stops by itself at the limit.
• Rate limits: download / upload in KB/s; by default they don't apply on the LAN (interconnect peers go full speed).
• Listen port (default 6881), UPnP / NAT-PMP port mapping, DHT, Local peer discovery (LSD): the defaults are sensible; if you see few connections, check whether the router blocks the port.
• Anti-leech: bans clients that only download or fake their progress.
• Tracker subscription: give it a tracker-list URL and new tasks get those trackers added — helps old releases with few seeders.
• Memory cap, max active downloads / seeds: lower them on phones.

Torznab indexers ​

If the built-in sources aren't enough (a private site, a niche index), go to Settings → Online services → Resource indexers → Torznab indexers → Add indexer: enter the endpoint and API key from Jackett / Prowlarr, optionally category IDs and a priority. Keys are never exported with backups and are synced to paired devices over interconnect (can be turned off).

If the built-in sources were disabled, searches say "No sources available for this search" — re-enable them under Settings → Online services → Resource indexers → Built-in sources.

Common situations ​

• Won't download / speed 0: check seeders first — 0 means find another release; then whether the router blocks the listen port and whether UPnP is on; try enabling a tracker subscription. One thing that's easy to overlook: IPv6 is off. Many seeders today are only reachable over IPv6; once IPv6 is enabled on both router and system (most ISPs provide it), the number of seeders you can connect to often jumps severalfold — and IPv6 peers can reach you without any port mapping.
• Nothing found: Nyaa is anime only; films and series are on apibay / Knaben; for how to write the query, see Can't find an anime?.
• Push to qBittorrent failed: WebUI address, credentials, and whether qB has "Web user interface" enabled; without path mappings across machines the finished files can't be found.
• Stopped seeding after renaming: renaming / moving inside Fushi goes through the engine and keeps seeding; renaming in a file manager breaks it.
• iOS: no search or download per App Store rules (the whole Browse module is absent).
• "This install is missing the built-in engine runtime": an incomplete package — reinstall the full installer or switch to an external qB.