docs(files): oxps runs filestash auth-off (LAN-only)

Two prod hosts now diverge on filestash auth: cochi stays htpasswd
(internet-facing), oxps runs FILES_AUTH=none/passthrough since it is
LAN-only, satisfying the internal-only gate. Document the per-host
status table and the flip-back rule for if oxps ever gains an internet
path.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plan/20-files.md

@@ -55,6 +55,20 @@ blocklisting (which would take `auth.` and the apex down with it, breaking login
 and the launcher for every player) all land on you. `render-config.sh` prints a
 loud warning when it renders this mode.
 
+**Per-host auth status (the two prod envs diverge):**
+
+| Host | `files.` reachability | `FILES_AUTH` | Notes |
+|---|---|---|---|
+| `cochi` | internet-facing | `htpasswd` | shared `uli` login, `$6$` hash |
+| `oxps` | **LAN-only** | **`none`** (passthrough) | auth off — gate satisfied (2026-07-23) |
+
+`oxps` runs auth-off deliberately: it is unreachable from the internet, so the
+open-upload-relay risk above does not apply. Applied host-locally (`.env`
+`FILES_AUTH=none` → `render-config.sh` → `docker compose up -d --force-recreate
+filestash`); nothing committed — `.env` and the rendered `config.json` are both
+gitignored per host. **If `oxps` ever gains an internet path, flip it back to
+`htpasswd` (or set `FILES_MOUNT_MODE=ro`) before exposing it.**
+
 **Shared credential ⇒ no audit trail, no per-person revocation.** You will never
 know who deleted a folder; rotating means re-telling everyone. Fine for a
 friends' media share — but nothing here is backed up, so treat the share as
@@ -196,6 +210,7 @@ writable file manager. Pin the digest; upgrade deliberately — same discipline
 
 - **Keycloak SSO** — needs oauth2-proxy + `FILES_AUTH=passthrough`. Not built.
 - **Anonymous access** (`FILES_AUTH=none`) — only once the host is internal-only.
+  **Done on `oxps`** (LAN-only, 2026-07-23); still `htpasswd` on `cochi`.
 - **Landing page link** — deliberately none on day one; `plan/18-landing-rework.md`
   is mid-rework, so revisit with WS5 (footer) rather than merging into a moving
   design.