docs(deploy): fallback UAT on Grok Bot computer :18181

When Tailscale cannot reach ubudual5060, Capture UAT serves from the
bot computer on :18181. Primary overnight remains :10881. Never touch
Ty local :18080 or legacy :10880.

deploy/INVENTORY.md

@@ -1,20 +1,35 @@
 # Host
 
-## Overnight Milestone 2 Capture (UAT)
+## Overnight Capture UAT (primary — when Tailscale is up)
 
 - Host: `ubudual5060` / Tailscale `100.64.0.9`
-- Container: `slabuploader-m2-overnight` (image `slabuploader-m2:overnight`)
+- Container: `slabuploader-m2-overnight` (image `slabuploader-m2:overnight`) — or salvage rebuild of the same role
 - Port: **10881** → 80
 - URL: `http://100.64.0.9:10881`
 - Replaces prior overnight container `slabuploader-m1-overnight` (same port).
 
-## Ty local Node/SvelteKit (do not overwrite)
+## Fallback UAT — Grok Bot computer (when Tailscale to 5060 is down)
+
+Use this path for salvage / Capture UAT until the box can reach `100.64.0.9` again.
+
+- Host: Grok Bot computer (slab-m1 box)
+- Serve: static Capture build (`frontend` → `npm run build`, then `vite preview` or equivalent static server)
+- Port: **18181** (chosen so it never collides with Ty local on 5060)
+- Bind: `0.0.0.0:18181`
+- URL (from this box): `http://127.0.0.1:18181` — Ty reaches it via the bot computer / whatever path the app exposes; Tailscale IP of this box when mesh returns
+- Branch for salvage: `salvage-one-woo-draft` (cut from `m2-ds`)
+- Do **not** require Docker on the box for this fallback.
+
+When Tailscale is restored, prefer primary overnight `:10881` again and stop advertising the fallback as the main UAT URL.
+
+## Ty local Node/SvelteKit on 5060 (do not overwrite)
 
 - Host: `ubudual5060` / `100.64.0.9`
 - Container: `slabuploader-m1`
-- Port: **18080** → 80 (inventory previously listed 10880; do not bind overnight there)
+- Port: **18080** → 80
 - URL: `http://100.64.0.9:18080`
-- **Never** recreate or remap this container for overnight UAT.
+- **Never** recreate or remap this container for overnight or box-fallback UAT.
+- **Never** bind overnight or fallback UAT to **10880** either (legacy Ty local).
 
-Future overnight Capture deploys use a **separate** container name and an open **108XX** port other than Ty’s local port.
+Future overnight Capture deploys use a **separate** container name and an open **108XX** port other than Ty’s local ports.
 Do not put a host name in the product spec.