agentbbs/docs/files.md
2026-06-23 10:46:00 +00:00

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# Files (SFTP) — member storage
AgentBBS gives every verified member file storage over **SFTP**, reachable with
the same SSH key they log in with. It rides the existing `:22` listener as an
SSH *subsystem*, so there is no new port and no separate account:
```bash
# interactive
sftp files@bbs.profullstack.com
# one-shot copies (same endpoint, same key)
scp report.pdf files@bbs.profullstack.com:/me/
rsync -avz ./site/ -e ssh files@bbs.profullstack.com:/me/site/
```
The username (`files`) is conventional and ignored — **identity is your SSH
key** (one key = one account, like the rest of the BBS). `scp`/`rsync` work
because they tunnel over the same SSH transport.
## Who can use it
**Members only — but free for every member.** Like IRC and News, file storage is
gated on membership, *not* on the paid Founding Lifetime plan:
- **Non-members can't connect.** A key that isn't a registered account is
refused at the SFTP handshake (`this key isn't a member — register first`), and
guests don't see the in-hub Files browser.
- **Every verified member can connect, run, and join** — free and paid alike.
There is no Premium gate anywhere in the Files path; the plan only affects
unrelated perks (custom email, domains, Tor).
- Operators can revoke an individual account's SFTP access (abuse response)
without touching its BBS login — see the management TUI below.
## Two areas
When you connect you see a virtual root with two directories:
| Path | What it is | Access |
|---|---|---|
| `/me` | Your **private** per-user workspace | read/write, quota-limited |
| `/public` | The single **shared public file area** (old-school BBS file area) | world-read; members-only write by default |
There is **no** path from one member's `/me` to another's — the only sharing
surface is the one public area (PRD §9.3, amended). Both areas are confined: a
path that tries to escape its root (`../`, an absolute path, or a planted
symlink) is rejected.
## Quotas
Each private workspace has a byte quota (default **1 GiB**, set by
`AGENTBBS_FILES_QUOTA_MB`). Writes that would exceed it fail. Operators can set a
per-user override in the management TUI. The public area is operator-managed and
not metered per user.
## In-BBS browser
Inside the hub, the **Files** entry opens a TUI browser for your workspace and
the public area: navigate, view text files, make directories, rename, and
delete, with a live usage gauge. Actual transfers happen over SFTP/scp/rsync (a
PTY can't move file bytes).
## Operator management TUI
Operators (the `$AGENTBBS_ADMINS` allowlist) reach the SFTP management console
with:
```bash
ssh sftp@bbs.profullstack.com # aliases: sftpadmin@, filesadmin@
```
Panes (Tab to switch):
- **Sessions** — live SFTP connections (user, remote, rx/tx, idle); `x`
force-disconnects.
- **Workspaces** — every member's usage vs. quota; `Q` sets a per-user quota,
`x` revokes/restores SFTP access (the BBS login is unaffected).
- **Public area** — `t` toggles members' write access; `x` removes an entry
(moderation).
Per PRD §9.2 the operator can inspect and act on hosted files; storage is not
content-blind.
## Configuration
| Var | Default | Meaning |
|---|---|---|
| `AGENTBBS_FILES` | `1` | enable the SFTP subsystem + Files plugin (`0` disables) |
| `AGENTBBS_FILES_QUOTA_MB` | `1024` | default per-user workspace quota (MB) |
| `AGENTBBS_DATA` | `./data` | storage lives under `<data>/files/{users,public}` |
## Implementation
- `internal/files` — a fully virtual Go SFTP server (`github.com/pkg/sftp` +
`crypto/ssh`); no OS users.
- `backend.go` — service, layout, quota/usage, live-session registry, operator
surface.
- `fs.go` — per-session virtual filesystem: `resolve()` is the single security
chokepoint (area confinement + symlink-escape guard) and the pkg/sftp
request handlers.
- `server.go` — the `wish.WithSubsystem("sftp", …)` handler: key auth → member
session → request server, with byte metering and force-disconnect.
- `tui.go` — the in-BBS member browser plugin.
- `admin.go` — the operator management TUI.
- Storage: `files_access` (per-user quota override + revoked flag) and
`files_settings` (e.g. public-write mode) in the shared SQLite store.
Security is covered by `internal/files/*_test.go`: path-traversal/confinement,
symlink-escape rejection, the public-write ACL, quota enforcement, and an
end-to-end run against a real SFTP client.