Merge branch 'main' into fix/sync-unreadable-subfolder

docs/ARCHITECTURE.md

@@ -379,6 +379,12 @@ Restore lists the device's folders, proposes a local path from the profile, and
 adds a synced folder bound to the remote uid. The download is an ordinary pass against an empty
 baseline. The user side is in [RECOVERY.md](RECOVERY.md).
 
+`Core::migrate_device` moves another device's top-level folders under this machine's device root.
+Device roots are separate shares on the main volume, so each folder is one server-side move that
+keeps its uid. A name already taken here gets the other device's name as a suffix. A synced folder
+that already tracked one of them keeps its `remote_uid` and only has its `remote_share_id`
+re-pointed. The moved folders are then offered by the ordinary restore.
+
 ---
 
 ## 8. Control protocol

docs/CHANGELOG.md

@@ -24,6 +24,13 @@ scratch (user data in `staging/` and `recovery/` is never touched by this).
 - **Switching to online-only trashed synced files that had become ignored.** Adding a synced path
   to `.pdfsignore` and then switching moved it to the Drive trash. Ignoring never deletes now, as
   the user guide says.
+  
+### Added
+- **Move another computer's backup to this one.** **Move to This Computer…** on the Computers page,
+  or `pdfs devices migrate UID`, moves every folder another computer backs up, for example an old
+  Windows PC, into this computer's backup on Proton Drive. Then it offers them for syncing here. The
+  folders move on Proton Drive itself, so nothing is uploaded again. The other computer stays in the
+  account, without those folders.
 
 ## [3.1.2] — 2026-10-08
 

docs/CLI.md

@@ -103,6 +103,7 @@ commands are for scripts and for cases where the mount is not available.
 | `pdfs devices rename UID NAME` | Rename a computer. |
 | `pdfs devices rm UID` | Remove a computer and its backup from the account. |
 | `pdfs devices adopt UID` | Make this machine continue another computer's backup, for example after a reinstall. `--clear` returns to matching by hostname. |
+| `pdfs devices migrate UID [--yes]` | Move another computer's folders into this computer's backup, then restore them here like `pdfs sync restore`. The other computer stays registered, without those folders. `--yes` skips the confirmation and accepts every proposed path. See [RECOVERY.md](RECOVERY.md). |
 
 ## Trash
 

docs/RECOVERY.md

@@ -133,6 +133,29 @@ pdfs sync restore --device UID
 The folders stay part of the other computer's backup and sync in both directions. This machine
 does not take over that computer's backup.
 
+### Moving another computer's backup here
+
+To switch computers for good, for example from a Windows PC to this Linux machine, move the old
+computer's folders into this computer's backup instead. Use **Move to This Computer…** on that
+computer's row, or:
+
+```bash
+pdfs devices list                 # find the old computer's UID
+pdfs devices migrate UID
+```
+
+Each folder moves on Proton Drive itself, so nothing is uploaded again and no storage is used
+twice. A folder whose name this computer already uses gets the old computer's name added, for
+example `Documents (DESKTOP-1)`. The restore picker then opens, as in
+[Step 3](#step-3-restore-the-folders), so you choose where each folder goes here.
+
+The old computer stays in your account, without those folders. Unlike
+[adoption](#step-2-continue-the-old-computers-backup), this machine keeps its own name and backup.
+
+> [!WARNING]
+> Stop Proton Drive on the old computer first. A client still running there sees its folders
+> disappear, and may upload them again as new.
+
 ## 3. How the restore works
 
 This section is for the curious and for anyone debugging a restore.

docs/USER_GUIDE.md

@@ -283,6 +283,9 @@ Proton Drive keeps earlier versions of every file. **Details → Versions…** i
   **Restore to This Computer…** downloads its folders here.
 - **Continue This Backup Here…** makes this computer take over another computer's backup, for
   example after reinstalling or replacing a machine. See [RECOVERY.md](RECOVERY.md).
+- **Move to This Computer…** moves another computer's folders into this computer's backup, for
+  example when you switch from Windows to Linux, and then offers them for syncing here. The other
+  computer stays in the list, without those folders.
 
 ## Search launcher