raw accept: Stem-Eindeutigkeit im Typverzeichnis erzwingen, --replaces als einziger Weg daran vorbei (schliesst #64)

Files changed:
- CHANGES.md
- VERSION
- instructions/wiki-ingest/SKILL.md
- raw/CONTRACT.md
- tools/CONTRACT.md
- tools/chemenu/commands/raw_cmd.py
- tools/chemenu/tests/test_raw_cmd.py

raw/CONTRACT.md

@@ -56,6 +56,26 @@ A bundle's type directory is the **source's** type, not any one file's - a diagr
 a `documents/` source is promoted from `incoming/documents/`, not `incoming/assets/`; `assets/` is
 for a source that is itself an asset.
 
+**The names occupied at `raw/<type>/` level - file stems and bundle directory names alike - are
+unique** (Gitea #64). Within a bundle, `handbuch.pdf` and `handbuch.md` sit side by side as always;
+the rule bites one level up, so a second, unrelated source cannot promote quietly into a bundle it
+does not belong to just because its own filename happens not to collide. A promote whose target
+name is already occupied is refused, naming both sanctioned ways past it without recommending
+either:
+
+```
+ERROR raw/documents/cluster.md already claims the stem "cluster" in raw/documents/.
+  These are two different intents and only you can tell them apart:
+    Same source, new edition   -> tools/wikitool raw accept --replaces raw/documents/cluster.md incoming/documents/cluster.md
+    A second, separate source  -> rename it in incoming/ (cluster-netzplan.md, cluster-2026-09.md) and accept it normally
+  raw accept does not guess which one this is.
+```
+
+An agent that gets this message does not pick a route on its own initiative - it shows the message
+to the human and waits, the same way it would for an exit-42 gate (AGENTS.md invariant 6), even
+though no gate fires here: the tool cannot ask the question itself, so the session passes it on
+instead of answering it.
+
 `tools/wikitool raw accept --page "Source - X" ...` additionally extends an existing source page's
 `raw_files:` in the same call. If that raises the page past one file, its already-promoted file is
 folded into the new bundle alongside the one(s) just accepted - the file that started single does
@@ -70,6 +90,15 @@ moment its immutability under the rules below begins, not the moment it was drop
 
 - **Immutable.** Never edit, reformat, summarize, or "clean up" a file after it lands here.
   Corrections belong in the `kb/` page that covers it, not in the source.
+- **Replaceable as a whole, never in part.** A source that gets a later edition is replaced
+  wholesale by `raw accept --replaces`, in one commit together with the update of every `kb/`
+  page compiled from it. Whether a new file is a later edition of an existing source or a
+  second, separate source is a human's decision and never the tool's or an agent's - `raw
+  accept` refuses and names both routes rather than choosing one (see above). The previous
+  edition is not kept as a file: it is overwritten, and `git log --follow <path>` is the
+  archive - no `-2026-09-05` suffix, no content-hash filename, no version field, because
+  `raw_files:` is an identifier (invariant 2) and Git already answers "what did this used to
+  say" losslessly (Gitea #64).
 - **Binary and image files still get ingested**, noting their presence and what they show,
   even when their content cannot be read directly.
 - **Every file is expected to be covered** by some source page, and one source page may cover