tools: Export- und Eingangsordner im Backup-Ziel - Überschneidungsregel nur noch auf <ziel>/git und den eigenen Maschinenordner, Laufzeitprüfung auf Vorfahren in upload collect und export run (#216); 10.1.0-beta.16

Files changed:
- CHANGES.md
- VERSION
- docs/how-to/back-up-to-a-synced-folder.md
- docs/how-to/collect-from-a-synced-folder.md
- docs/how-to/export-to-a-synced-folder.md
- docs/reference/commands/exports.md
- docs/reference/commands/raw-material-and-uploads.md
- docs/reference/configuration.md
- tools/CONTRACT.md
- tools/chemenu/backup.py
- tools/chemenu/collect.py
- tools/chemenu/commands/export_cmd.py
- tools/chemenu/commands/upload_cmd.py
- tools/chemenu/config_shapes.py
- tools/chemenu/page_export.py
- tools/chemenu/tests/test_collect.py
- tools/chemenu/tests/test_export_run.py
- tools/chemenu/upload.py

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

docs/how-to/back-up-to-a-synced-folder.md

@@ -11,6 +11,7 @@ push to and a copy of the files on this machine that are not in git. What the se
 
 - [Why the instance does not live in the synced folder](#why-the-instance-does-not-live-in-the-synced-folder)
 - [Set it up](#set-it-up)
+- [One folder for the backup, the intake and the export](#one-folder-for-the-backup-the-intake-and-the-export)
 - [What is backed up, and what is not](#what-is-backed-up-and-what-is-not)
 - [Restore](#restore)
 - [One device writes](#one-device-writes)
@@ -91,6 +92,29 @@ still happened. Fix what the line names - a synced folder that is not there, a f
 writable - and run `tools/wikitool backup run`. Another publish does not help: it has nothing new to
 push.
 
+## One folder for the backup, the intake and the export
+
+The target may be the one folder your whole setup shares. The backup writes only into `git` and into
+the folder of its own machine; everything else in the target belongs to the sync folder, so an
+[intake folder](collect-from-a-synced-folder.md) and an
+[export folder](export-to-a-synced-folder.md) can sit beside them:
+
+```
+<OneDrive - company>\Chemenu\          backup.target
+    git\                               the bare repository (backup init, publish)
+    <MACHINE>\                         this machine's data (backup run, publish)
+    Inbox\                             intake channel, handler folder
+    Export\                            export target
+```
+
+The rule behind it: no export and no intake folder may be, or lie in, `<target>\git` or a machine
+folder. For the export that holds from above as well (its path must not contain them either); an
+intake folder may sit above them, since `upload collect` reads only the top level of its folder.
+`doctor` checks the part that the settings can show. What they cannot show - the folder of another
+machine, or one that a machine starts to fill later - is checked when the command runs: `upload
+collect` and `export run` refuse a folder that holds or lies in a `.chemenu-backup.json`, a bare
+repository or (for `upload collect`) a `.wikitool-export.json`, and touch nothing in it.
+
 ## What is backed up, and what is not
 
 | Path | Backed up | Why |