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21 — School PC File Workflow (OneDrive Transit)

How files move between the Z2's files share and a college-managed lab PC (AutoCAD and other software the tablet can't run) without putting the lab PC on the tailnet. The Galaxy Tab is the bridge: it is on the tailnet and can reach both the Z2 and OneDrive. OneDrive, on the college Microsoft 365 account, is only the courier.

Companion to 20-galaxy-tab.md (the tablet and its Material Files SMB setup) and 04-samba.md (the files share).

Why

The Zephyrus stays docked at home to keep the backpack light. The tablet covers notes, browsing and file viewing, but some coursework has to be done on college lab PCs. Those PCs are managed by the college: you sign in with the @conestogac.on.ca account, you have no admin rights, and the profile may be wiped at logoff. They can't reach the Z2, because every service on it is tailnet-only.

The rule this workflow keeps: only trusted devices join the tailnet. The lab PC never connects to the Z2. It only touches OneDrive, which it already supports and which the college sanctions.

  Z2 Mini /data/files ──SMB over tailnet── Galaxy Tab ──HTTPS── OneDrive (college) ──── Lab PC
        (master copy)                       (bridge)              (transit only)        (editing)

The rules

  1. The Z2 is the master copy. OneDrive only holds a file while it is out being edited. Once a file is back on the Z2, delete it from OneDrive.
  2. Use one transit folder. Everything passes through OneDrive/z2mini-transit/. No other OneDrive folder is part of this workflow.
  3. Don't edit the Z2 copy while a file is out. Two diverging copies is the main way this workflow loses work.
  4. Coursework only. OneDrive here belongs to the college tenant, so college IT can access it. Nothing personal goes through it.

One-time setup

OneDrive. Sign in to onedrive.live.com with the college account and create a folder named z2mini-transit.

Tablet. The OneDrive app was removed in the debloat (20-galaxy-tab.md), so the tablet uses OneDrive in Chrome. No extra app is needed:

  • Uploading goes through Chrome's file picker. Material Files registers the Z2 share as a system DocumentsProvider, so z2mini appears in the picker and files upload straight from the share.
  • Downloading saves to the tablet's local Download/ folder. From there, Material Files moves (not copies) the file to z2mini/files/..., so no stale copies build up on the tablet.

Tailscale must be connected on the tablet for the z2mini entry to appear.

Lab PC. Nothing to install. If File Explorer has an OneDrive - <college> folder in its sidebar, OneDrive is syncing and z2mini-transit is in it. If not, use OneDrive in the browser.

Scenario 1 — Editing an existing file

On the tablet (before class):

  1. Open OneDrive in Chrome and go to z2mini-transit/.
  2. Upload → Files, then in the picker choose z2mini and the file under files/....

On the lab PC:

  1. Open the file directly from the synced OneDrive - <college>/z2mini-transit/ folder and save it back there. Without a synced folder: download the file from OneDrive in the browser, work on the local copy, then upload it back to z2mini-transit/, replacing the original.
  2. Before logging off, confirm the upload finished. In File Explorer, the file shows a green check or cloud icon, not the blue syncing arrows. In the browser, z2mini-transit/ shows the new modified time. The profile may be wiped at logoff, and a save that hadn't synced is lost.

On the tablet (after class):

  1. In OneDrive (Chrome), download the updated file.
  2. In Material Files, move it from Download/ to its original location under z2mini/files/..., overwriting the old version.
  3. Delete the file from z2mini-transit/.

Scenario 2 — New file created on the lab PC

On the lab PC:

  1. Create the file directly in OneDrive - <college>/z2mini-transit/, not on the Desktop. That way there's no "remember to copy it" step at the end.
  2. Before logging off, confirm the upload finished (as in step 4 above).

On the tablet:

  1. Download it from OneDrive in Chrome, then move it from Download/ to its place under z2mini/files/... with Material Files.
  2. Delete it from z2mini-transit/.

AutoCAD specifics

  • Drawings with xrefs, images or custom fonts: moving only the .dwg breaks those links. Run eTransmit (Application menu → Publish → eTransmit) to bundle the drawing and all its dependencies into a single .zip, and move that zip through z2mini-transit/.
  • Clutter: AutoCAD writes .bak, .sv$ and .dwl/.dwl2 lock files next to the drawing. Leave them in OneDrive and don't copy them back to the Z2. They go when the transit folder is emptied.
  • Close the drawing before relying on the sync. While AutoCAD has a drawing open, its lock files stay in place and the last save may not be uploaded yet.

Verifying

  • After a round trip: the file on z2mini/files/... has the modified time from the lab session, and z2mini-transit/ is empty.
  • Version history: if a file came back wrong, OneDrive keeps previous versions. In the browser, right-click the file → Version history before deleting it from transit.

Troubleshooting

z2mini doesn't show up in Chrome's upload picker: - Tailscale is disconnected on the tablet. Open the Tailscale app. - In the picker, open the sidebar (☰). Providers are listed there, not under Recent.

Lab PC has no OneDrive folder in File Explorer: - OneDrive isn't set up on that machine or profile. Use onedrive.live.com in the browser, and save every working copy back to OneDrive before logging off.

File in OneDrive is older than the work done in the lab: - The save didn't sync before logoff, or the work was saved to the local Desktop. Check OneDrive's Version history and Recycle bin. If neither has it, the work is gone, which is why step 4 checks the sync before logging off.

AutoCAD opens the drawing with missing xrefs or images: - The .dwg was moved on its own. Re-send it as an eTransmit zip.

Two different versions of the same file: - The Z2 copy was edited while the file was out. Compare the modified times, keep the newer one, and follow rule 3 from then on.

Decisions

Decision Reasoning
Lab PC never joins the tailnet The PC is shared, managed by the college and may be monitored, so it can't be trusted with a tailnet key. Every device on the tailnet is one Gabriel controls
OneDrive (college account) as courier over a USB stick One less thing to carry, version history built in, and lab PCs already support it. The files are only in transit, so the college owning the storage (and the account ending at graduation) doesn't matter
Portable Tailscale on a USB stick — rejected The Windows client needs admin rights for its service and network adapter. The unofficial userspace mode only gives a local proxy that Explorer, SMB and AutoCAD can't use, lab PCs commonly block programs run from USB drives, and it may break the college's IT rules
Pi Zero "smart stick" (USB gadget) — rejected Needs its own Wi-Fi. Posing as a USB drive can't show live network files without corruption, which reduces it to a snapshot stick. Posing as a network adapter needs a driver and puts the lab PC on a path to the tailnet, which is the thing being avoided
Public web file manager (File Browser behind Cloudflare Tunnel + Access) — deferred Works from any browser with nothing installed, but it would make the Z2 reachable from the public internet for the first time. Not worth that change at current lab-PC frequency. Revisit if the manual tablet step becomes a daily chore
OneDrive in Chrome on the tablet, not the OneDrive app The app was removed in the debloat. Chrome plus the Material Files picker covers upload and download. If the browser flow gets tedious, restore the app with adb shell cmd package install-existing com.microsoft.skydrive
No automatic Z2 ↔ OneDrive sync (rclone) College Microsoft 365 tenants commonly block third-party app consent, and automatic sync would make OneDrive a second live copy, which rule 1 rules out