feat(files): SFTP member storage — private workspaces + shared public area + mgmt TUI

Implements M4 (Files). A fully virtual Go SFTP server (pkg/sftp + crypto/ssh, no OS users) wired as an "sftp" subsystem on the existing :22 wish listener, so members reach their files with their login key: sftp files@bbs.profullstack.com # scp/rsync ride the same endpoint Identity is the SSH key (the username is conventional/ignored). Two areas per session: a private, quota-limited /me workspace and a single shared public file area /public (old-school BBS file area; world-read, members-only write by default, operator-moderated). This reverses the old NG1 "no sharing" boundary in favour of one sanctioned, inspectable sharing surface (PRD §9.3 amended). internal/files: - backend.go service, layout, quota/usage, live-session registry, operator API - fs.go per-session virtual FS; resolve() is the single security chokepoint (area confinement + symlink-escape guard) + pkg/sftp request handlers - server.go subsystem handler: key auth -> member session -> request server, with byte metering and force-disconnect - tui.go in-BBS member browser (hub plugin "Files") - admin.go operator management TUI: sessions, workspaces/quotas, public area Operator console: ssh sftp@<host> (allowlist-gated; sftpadmin@/filesadmin@ aliases) — list/disconnect sessions, set per-user quotas, revoke SFTP access, toggle public write, moderate the public area. store: files_access (per-user quota override + revoked) and files_settings (public-write mode) tables + methods. main.go wiring guarded by AGENTBBS_FILES (+ AGENTBBS_FILES_QUOTA_MB, default 1 GiB). Route names reserved. Tests (incl -race): path traversal/confinement, symlink-escape rejection, public-write ACL, quota enforcement, usage accounting, and an end-to-end run against a real SFTP client. Docs: docs/files.md; PRD §5.3/§5.3.1/§9.3 + README updated. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-08-13 14:27:27 +00:00 · 2026-06-23 09:35:04 +00:00 · 2026-06-23 09:35:04 +00:00 · 6dc94bd784
commit 6dc94bd784
parent 68899180a7
18 changed files with 2223 additions and 27 deletions
--- a/docs/PRD.md
+++ b/docs/PRD.md
@ -30,7 +30,7 @@ supply inventory. The BBS hub is the funnel that builds that audience.
 |---|---|
 | `profullstack.com` | Primary BBS host — `ssh play@profullstack.com` (guest) and member access |
 | `logicsrc.com` | Home of the AgentGames spec and developer/agent-facing docs |
-| `cl1.tech` | Managed file-transfer service (SFTP product), surfaced in-BBS as a plugin |
+| `bbs.profullstack.com` | Member file storage over SFTP — `sftp files@bbs.profullstack.com` (same SSH key as login) |

 ### 1.2 One-line pitch

@ -100,7 +100,7 @@ supply inventory. The BBS hub is the funnel that builds that audience.
        ▼                 ▼                   ▼                 ▼
   ┌─────────┐      ┌───────────┐      ┌────────────┐    ┌──────────┐
   │ Arcade  │      │ AgentGames│      │ Files       │    │ AgentAd  │
-   │ plugin  │      │ plugin    │      │ (cl1.tech)  │    │ plugin   │
+   │ plugin  │      │ plugin    │      │ (SFTP)      │    │ plugin   │
   └────┬────┘      └─────┬─────┘      └─────┬──────┘    └────┬─────┘
        └─────────── sandbox runner ─────────┘                │
                          │                                   │
@ -193,20 +193,46 @@ Same backend, inverted player: **AI agents connect and compete**.
 - **Spec home:** the protocol and SDK live on `logicsrc.com` for agent
  developers.

-### 5.3 Files (cl1.tech)
+### 5.3 Files (SFTP)

-A managed file workspace, surfaced in-BBS and as a standalone SFTP product on
-`cl1.tech`.
+Member file storage for bbs.profullstack.com, surfaced in-BBS and reachable
+directly over SFTP with the member's existing SSH login key.

- **Model:** strictly **private, per-user** storage. Each account is chrooted to
-  its own directory tree with a disk quota.
- **Access:** SFTP via OpenSSH `internal-sftp` (chrooted) or a Go SFTP server
-  (`pkg/sftp` + `crypto/ssh`) for fully virtual users, quotas, and logging in
-  application code.
- **In-BBS view:** a TUI file browser for the user's own workspace (list,
-  rename, delete, view usage vs. quota).
- **Explicitly out of scope:** any user-to-user transfer, shared drop, or
-  public directory feature (§9.3, NG1).
+- **Model:** two areas per server:
+  1. **Private, per-user** storage — each account is virtually chrooted to its
+     own directory tree with a disk quota. The default and primary surface.
+  2. **A single shared public file area** — an operator-run, communal directory
+     (old-school BBS file area). World-readable; write access is a tunable
+     (members-only by default). Operator-moderated; not encrypted or blind.
+- **Access:** a **virtual Go SFTP server** (`pkg/sftp` + `crypto/ssh`) for fully
+  virtual users, app-level quotas, per-path ACLs, and logging — no OS users.
+  Authentication is by the member's existing AgentBBS **SSH public key**, so a
+  member reaches their private files with the same key they log in with
+  (`sftp files@bbs.profullstack.com`). `scp`/`rsync -e ssh` work over the same
+  endpoint.
+- **In-BBS view:** a TUI file browser for the user's own workspace and the
+  shared area (list, rename, delete, up/download path, view usage vs. quota).
+- **Operator TUI:** an admin management surface for the SFTP server — list
+  sessions/connections, browse/quarantine files in any workspace and the public
+  area, set/adjust quotas, toggle public-write, and revoke access (§5.3.1).
+- **Out of scope:** direct peer-to-peer or brokered transfer **between** private
+  workspaces. Sharing happens only through the single moderated public area
+  (§9.3, NG1 as amended).
+
+#### 5.3.1 Management TUI
+
+A `bubbletea` admin console (gated to operators/admins), reachable both as an
+in-BBS admin route and standalone. Panes:
+
+- **Sessions:** live SFTP connections (user, key fingerprint, bytes, idle time),
+  with force-disconnect.
+- **Workspaces:** per-user usage vs. quota; drill into any tree to view,
+  quarantine, or delete files for abuse response (consistent with §9.2 — the
+  operator can act on its own systems).
+- **Public area:** browse the shared file area, moderate/remove entries, toggle
+  the members-only write flag.
+- **Quotas & access:** set default and per-user quotas; revoke a user's SFTP
+  access without touching their BBS login.

 ### 5.4 AgentAd (marketplace)

@ -306,12 +332,18 @@ The platform does **not** adopt content-blind/zero-knowledge storage designed so
 the operator cannot inspect hosted files. Operability, abuse response, and
 auditability require that the operator can act on its own systems.

-### 9.3 No user-to-user distribution
+### 9.3 No peer-to-peer distribution (amended)

-File workspaces are private and per-user. The platform provides **no** feature
-for users to share or transfer files to one another — no shared directories, no
-peer drop, no brokered transfer — in any transport or encryption configuration.
-This is a hard product boundary, not a tunable.
+Private workspaces remain private and per-user: the platform provides **no**
+feature for users to transfer files directly to one another — no peer drop, no
+brokered workspace-to-workspace transfer — in any transport or encryption
+configuration. That direct path is a hard product boundary, not a tunable.
+
+Sharing is permitted **only** through a **single operator-run public file area**
+(§5.3): a moderated, non-blind communal directory, world-readable, with
+members-only write by default. Because it is operator-run and inspectable
+(§9.2), the operator can moderate and act on takedown notices (§9.4). This is
+the one sanctioned sharing surface; everything outside it stays private.

 ### 9.4 Standard hosting compliance

@ -333,7 +365,7 @@ from the start.
 | **M1 — Arcade** | doom-ascii + Freedoom/shareware, sandbox runner, guest play, member saves & leaderboards |
 | **M2 — Admin** | plugin enable/disable, user moderation, session audit |
 | **M3 — AgentGames** | game protocol, phase-1 catalog, agent auth, ladders, replays; spec published on logicsrc.com |
-| **M4 — Files (cl1.tech)** | private per-user SFTP workspaces, quotas, in-BBS browser |
+| **M4 — Files (SFTP)** | virtual Go SFTP server (key auth), private per-user workspaces + quotas, single shared public area, in-BBS file browser, operator management TUI |
 | **M5 — AgentAd** | two-sided marketplace, buyer storefront, seller dashboard, creative review, revenue share |
 | **M6 — Hardening & scale** | rate limits, fail2ban, metrics, Postgres migration path, web buyer dashboard |

@ -345,8 +377,10 @@ from the start.
   websocket/API endpoint? (Affects how non-interactive agents authenticate.)
 2. **Sandbox technology:** Docker/Podman per session vs. `systemd-run` transient
   scopes — which fits the target VPS footprint best?
-3. **Account model for the Files plugin:** real chrooted system users via
-   OpenSSH `internal-sftp`, or fully virtual users via a Go SFTP server?
+3. ~~**Account model for the Files plugin:** real chrooted system users via
+   OpenSSH `internal-sftp`, or fully virtual users via a Go SFTP server?~~
+   **Resolved:** virtual Go SFTP server (`pkg/sftp` + `crypto/ssh`), key-based
+   auth against the AgentBBS account store. (§5.3)
 4. **AgentAd inventory mix:** which surfaces ship first (interstitials vs. hub
   banners vs. sponsored ladder slots)?
 5. **Web footprint:** does the AgentAd buyer dashboard warrant a web app in v1,
--- a/docs/files.md
+++ b/docs/files.md
@ -0,0 +1,95 @@
+# 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.
+
+## 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.