release: 4.5.0 - beide Update-Wege in Code (upstream merge, dist upgrade)

Files changed:
- CHANGES.md
- VERSION

AGENTS.md

@@ -238,7 +238,8 @@ Every `tools/wikitool` call has exactly four outcomes:
    produced.
 
 After the single allowed retry - or immediately, for the non-idempotent commands `new`,
-`log append`, and `publish` - stop and report the exact command and error text to the user.
+`log append`, `publish`, and `upstream merge` - stop and report the exact command and error
+text to the user.
 
 Per-command detail (what exit 1 means, whether the command is atomic, whether a retry is
 safe) is in [tools/CONTRACT.md](tools/CONTRACT.md). A gate refusal is not a validation error -

CHANGES.md

@@ -35,6 +35,205 @@ dev-checkout concern - readable here, never shipped as something to parse.
 
 ---
 
+## 4.5.0 - 2026-09-04 - Beide Update-Wege in Code: upstream merge fuer Clones, dist upgrade fuer Tarball-Instanzen
+
+**Author:** Torben Nehmer
+
+<!-- wikitool:bumps -->
+- Faktenkorrekturen in der 4.4.0-Prosa; DEVELOPMENT.md ohne zweite Kommandobeschreibung
+- wikitool upstream merge/verify: code procedure for taking a stack update, ownership.py as the shared stack/instance boundary
+- upstream merge: combined-commit regression test (edit+add+delete+contract+template+contract-delete in one commit)
+- upstream merge: keep gitignored local data under a content stage, refuse a merge git never opened, report what actually changed
+- dist upgrade: apply a stack update, not just detect one (#7)
+- dist upgrade: Stamp-Semantik nach --keep-local benannt, docs/ownership-and-templates.md auf drei Eigentumsklassen nachgezogen
+<!-- /wikitool:bumps -->
+
+Die Prosa zu 4.4.0 - Changelog-Eintrag, `docs/version-model.md`, `instructions/dev/version-parts.md`,
+`DEVELOPMENT.md` - entstand ungeprüft: kein maschineller Check liest sie, und die Sitzung, die sie
+schrieb, hat den dafür vorgesehenen Modellwechsel aus `stack-dev` Schritt 6 übersprungen. Ein
+nachgeholter Durchgang hat drei Fehler gefunden, von denen der erste der teuerste war.
+
+**Der Befund war an einer Stelle schlicht falsch.** Changelog und `docs/version-model.md`
+behaupteten, unter dem alten Modell seien Nummern vergeben worden, die „nie ausgeliefert" wurden -
+im Changelog sogar mit einer erfundenen Zahl („fünf Minor-Bumps ... vier nie ausgeliefert"). Das
+Gegenteil stimmt: weil `release.yml` auf jede `VERSION`-Bewegung feuerte, wurde **jeder** Bump zu
+einem echten, getaggten Release. Der 2026-09-03 hat vier davon in sechs Stunden erzeugt (`4.3.0`
+bis `4.3.3`), zwei für reine Prosa-Änderungen. Der Schaden war nie ein Phantom-Release, sondern
+dass „Release" aufhörte, etwas zu bedeuten - vier Upgrades an einem Nachmittag sind für einen
+Konsumenten kein kleineres Versprechen, sondern ein unleserliches. Beide Stellen tragen jetzt den
+tatsächlichen Vorgang samt Beleg.
+
+Dazu zwei kleinere Korrekturen: `version-parts.md` nannte den Stack weiterhin `2.x` (er steht bei
+`4.x`), und `DEVELOPMENT.md` trug eine Tabelle, die für jeden Verify-Befehl ein zweites Mal
+beschrieb, was er prüft - eine Kopie dessen, was `tools/CONTRACT.md` hält und `docs verify` dort
+gegen die CLI prüft. Die Tabelle ist raus; dass die Datei selbst außerhalb der von diesem Check
+abgedeckten Dokumente liegt, steht jetzt an ihrer Stelle. Der Code-seitige Teil davon - ob
+`DEVELOPMENT.md` in `docs_verify.STAGE_READMES` gehört - hängt an #47, zusammen mit der Lücke im
+Skill, die den übersprungenen Modellwechsel überhaupt erst unauffällig gemacht hat.
+
+Kein Verhalten geändert, nur Prosa - und bewusst als laufender Kandidat gelassen statt fixiert:
+CIs Version-Gate verlangt die `VERSION`-Bewegung, ein Release verlangt sie nicht. Genau dafür gibt
+es das Modell aus 4.4.0.
+
+**Zweiter Bump auf demselben Kandidaten (#30):** `git merge upstream/main` behandelt einen
+bewegten Korpus asymmetrisch - eine gelöschte, upstream-geänderte Seite meldet sich als Konflikt,
+eine neu angelegte Seite wird still gestaged, nur eine beidseitig gelöschte Seite ist harmlos. Die
+Prosa-Prozedur in `private-instance.md` § "Taking a stack update" hat das geschlossen, aber mit
+vier eigenen Fehlern: der Pfadsatz stand dreifach (im Skript, im Kontroll-Grep, implizit in
+`dist_cmd.py`); eine vom Upstream **gelöschte** Maschinerie-Datei wurde von `git checkout
+MERGE_HEAD -- <pfad>` still ignoriert, weil das Skript kein `set -e` hatte; ein echter Konflikt in
+`tools/`/`types/`/`instructions/` endete in einem von der Prosa nirgends erwähnten offenen Merge;
+und ein *neuer* Maschinerie-Pfad unter einer Content-Stage hätte die Literal-Liste nie erreicht.
+
+Die Eigentumsgrenze ist jetzt ein Prädikat statt einer Liste: `chemenu/ownership.py`,
+`is_stack_owned(relative)`, wahr für `<stage>/CONTRACT.md` direkt unter einer Content-Stage
+(`kb`, `raw`, `work`, `reports`) und für jeden Pfad, der dort auf `.template` endet - nicht
+rekursiv, `kb/<collection>/COLLECTION.md` bleibt seit #39 instanzeigen. `dist_cmd.py` liest das
+Modul jetzt statt einer eigenen `_CONTENT_ALLOWED_NAMES`-Liste zu pflegen, und
+`CONTRACT_ONLY_STAGES` leitet sich aus `ownership.CONTENT_STAGES` ab statt die drei Stage-Pfade
+ein zweites Mal aufzuschreiben - ein Test hält fest, dass beide Sichten nicht auseinanderlaufen
+können.
+
+Neu: `wikitool upstream merge [--remote upstream] [--branch main] [--no-fetch]` und `wikitool
+upstream verify --since <rev> [--until HEAD]`. `merge` prüft Vorbedingungen (sauberer Baum, kein
+laufendes Merge, Remote löst auf), warnt statt zu blockieren, wenn `.wikitool-remotes.json` fehlt,
+hält den Merge offen (`--no-commit --no-ff`), zwingt jede Content-Stage auf die lokale Seite
+zurück, holt dann über die Vereinigungsmenge der Bäume von `MERGE_HEAD` und `HEAD` genau die
+stack-eigenen Pfade zurück - inklusive einer Löschung, falls der Upstream einen Maschinerie-Pfad
+entfernt hat -, verweigert bei verbliebenen unaufgelösten Pfaden ohne zu committen, committet
+sonst und verifiziert den entstandenen Commit mit derselben Logik wie `verify` - ein Fund dort
+wird laut gemeldet und **nicht** automatisch zurückgerollt. Nicht idempotent (AGENTS.md § Tool
+error contract), nicht budget-exempt; `verify` liest nur und ist wie `migrate verify` von der
+Budget-Gate ausgenommen. Die Mass-Update-Gate greift bei einem Merge-Commit strukturell nicht -
+das steht jetzt als eigener Absatz in `instructions/gates.md`, mit `upstream merge`s eigener
+Nachkontrolle als der Sicherung, die hier tatsächlich trägt.
+
+`private-instance.md` § "Taking a stack update" verweist jetzt auf den Befehl statt das Skript
+auszuschreiben; die Pfadtabelle bleibt als Erklärung stehen, ist aber nicht mehr die operative
+Liste. Vorschlag B (eigenes Demo-Repo) bleibt zurückgestellt, siehe #30.
+
+23 neue Tests unter `test_upstream_cmd.py` (35 Fälle mit der parametrisierten
+`is_stack_owned`-Tabelle) decken die Fälle aus der Spezifikation ab:
+gelöschte vs. geänderte vs. neu angelegte Seiten, `kb/CONTRACT.md`- und Template-Änderungen,
+`kb/entities/COLLECTION.md` bleibt lokal, eine gelöschte `raw/CONTRACT.md` landet, ein neuer
+Template-Pfad landet, ein offener `work/`-Lauf landet nicht, ein echter `tools/`-Konflikt lässt
+den Merge offen, ein schmutziger Baum wird unberührt abgewiesen, "bereits aktuell" ist ein No-op,
+die Publish-Remote-Gate-Warnung, `verify` gegen einen von Hand verpfuschten Merge, und die
+`dist_cmd`/`ownership`-Konsistenz.
+
+**Dritter Bump auf demselben Kandidaten:** die im Akzeptanzkriterium geforderte Kombinationsprobe
+fehlte noch - ein einzelner Upstream-Commit, der Editieren, Anlegen, Löschen einer Seite, eine
+Contract-Änderung, eine Template-Änderung und eine Contract-Löschung gleichzeitig bewegt. Jetzt
+als `test_one_upstream_commit_mixing_every_case_at_once` nachgetragen; alle sechs Erwartungen in
+einem `upstream merge`-Aufruf verifiziert.
+
+**Vierter Bump: zwei Fehler, die ein Review-Durchgang nach dem Publish gefunden hat.** Beide
+waren in der ersten Fassung enthalten, beide hätten Daten vernichtet, und keiner der bestehenden
+Tests hat sie berührt.
+
+*Erstens: die Content-Stage wurde als Ganzes gelöscht.* `_restore_stage_to_local` hieß in der
+ersten Fassung `shutil.rmtree(stage_dir)` — die wörtliche Übersetzung des `rm -rf kb raw` aus der
+Prosa-Prozedur. Für `kb/` und `raw/` ist das harmlos, weil dort nichts Ignoriertes liegt. Für die
+beiden Stages, die dieses Issue *neu* in den Satz aufgenommen hat, ist es das nicht: `reports/`
+ist bis auf seinen Contract komplett gitignored und trägt genau die Daten, die nirgends sonst
+existieren — die Telemetrie-Traces, aus denen `eval score` liest, gespeicherte Eval-Berichte,
+alte Lint-Reports. In dieser Instanz standen zum Zeitpunkt des Fundes 497 Trace-Verzeichnisse
+unter `reports/telemetry/`; ein einziger `upstream merge` hätte sie alle gelöscht, und zwar
+stillschweigend, weil git von ignorierten Dateien nichts meldet. Die Stage wird jetzt über die
+**getrackten** Pfade beider Bäume zurückgesetzt statt über das Verzeichnis; ignorierte lokale
+Daten bleiben unberührt. Leergewordene Verzeichnisse werden aufgeräumt, aber nur wirklich leere.
+
+*Zweitens: ein Merge, den git nie eröffnet hat, hätte die Maschinerie gelöscht.* Der Exit-Code
+von `git merge --no-commit --no-ff` wird bewusst ignoriert (Konflikte unter den Content-Stages
+sind erwartet). Nur: wenn git das Merge gar nicht erst eröffnet — unverwandte Historien, eine
+ignorierte Datei im Weg —, gibt es kein `MERGE_HEAD`, `_tree_paths("MERGE_HEAD")` liefert die
+leere Menge, und **jeder** stack-eigene Pfad in `HEAD` fällt damit in den Zweig „der Upstream hat
+ihn gelöscht": `kb/CONTRACT.md`, `raw/CONTRACT.md` und sämtliche Templates werden entfernt. Der
+Kommando-Ablauf prüft jetzt nach dem Merge-Aufruf, dass tatsächlich ein Merge offen ist, und
+bricht sonst ab, ohne den Baum angefasst zu haben. Beide Fehler haben je einen Regressionstest,
+und beide Tests wurden gegen die alte Fassung laufen gelassen, um zu zeigen, dass sie sie
+tatsächlich fangen.
+
+Dazu eine Ehrlichkeitskorrektur an der Erfolgsmeldung: sie zählte die *wiederhergestellten*
+Pfade, nicht die geänderten — ein Merge, der eine Datei bewegt, meldete vier oder fünf. Sie fragt
+jetzt `git diff` zwischen Vor- und Nach-Commit, kennzeichnet Löschungen, und stimmt damit mit dem
+überein, was ein Leser nachprüfen würde. `docs/ownership-and-templates.md` hat einen Abschnitt
+bekommen, warum die Grenze ein Prädikat und keine Liste ist — die Begründung, die dieses Issue
+erarbeitet hat, gehörte in die Hintergrunddoku und nicht nur in einen Changelog-Eintrag.
+
+**Fünfter Bump: `wikitool dist upgrade` (#7), der zweite der beiden Update-Wege.** `upstream
+merge` oben bedient eine Instanz mit gemeinsamer Git-History; `dist upgrade` bedient eine
+Instanz aus einem Tarball, ohne History, die bislang eine rein manuelle Prozedur in
+`INSTALL.md` durchlaufen musste - Schritt 4 verlangte einen sha256-Vergleich von Hand gegen den
+`files`-Block der alten `.wikitool-release.json`.
+
+Die tragende Regel: die Schreibmenge ist genau der `files`-Block der *neuen*
+`.wikitool-release.json`, minus was ein Export aus einer leeren Vorlage neu sät
+(`chemenu.ownership.is_export_stub`, wie bisher schon für `kb/log.md`/`.gitkeep`) oder einmalig
+sät und danach der Instanz gehört (`chemenu.ownership.is_upgrade_preserved`, neu für
+`.wikitool-kb.json` und `CHANGES.md`), plus der Stamp selbst. Jeder Kandidatpfad wird gegen die
+*alte* Instanz-Summe klassifiziert: unverändert wird geräuschlos überschrieben, neu im Release
+wird angelegt, lokal verändert oder gelöscht wird **nie** still überschrieben - der Lauf bricht
+mit der vollständigen Liste ab, außer `--keep-local` sagt ausdrücklich, dass die Dateien liegen
+bleiben sollen. `--prune` entfernt zusätzlich aus dem Release entfallene Dateien, aber nur
+solche, die seit der Installation unverändert sind.
+
+Die Migrationskette nach dem Tausch wird aus den `instructions/migrations/` des *neuen* Baums
+ermittelt (`kb_state.load_migrations` bekam dafür einen `directory`-Parameter) und nur
+gemeldet, nie ausgeführt - es gibt bewusst kein `migrate run`. Eine bereits gegen die
+*installierte* Maschinerie offene Kette lässt den Befehl abbrechen, bevor er die Quelle
+überhaupt öffnet. `kb_state.divergent_files()` (bisher nur von `migrate status` gelesen) ist
+jetzt eine dünne Hülle um das neue, zwei-Baum-fähige `compare_against_stamp()` - gleiches
+Verhalten für den bestehenden Aufrufer, wiederverwendbar für `dist upgrade`s eigenen Vergleich.
+
+Quelle ist immer ein bereits vorhandenes Verzeichnis oder `.tar.gz` - kein Download, das bleibt
+allein `version check`s Sache. Ein Tarball muss genau ein Top-Level-Verzeichnis enthalten (die
+Form, in der `release.yml` es baut) und wird gegen eine `.sha256`-Beidatei geprüft, falls eine
+danebenliegt (fehlt sie: WARN, kein Abbruch). Weitere Abbruchgründe vor jedem Schreiben: fehlende
+lokale `VERSION`/`.wikitool-kb.json`/Stamp mit `files`-Block, ein schmutziger Arbeitsbaum (kein
+Git-Repo ist ein WARN, keine Sperre), eine Vorab-Version (`-beta.N`) ohne `--pre`, sowie ein
+Downgrade; Gleichstand ist ein No-op. Ein Grenzübertritt der Kompatibilität wird laut gemeldet,
+blockiert aber nicht. Committet und pusht nichts (Invariante 5).
+
+Gegenüber dem ersten Entwurf des Issues zwei Korrekturen, die dort auch nachgetragen sind: der
+`files`-Block wurde entgegen der ursprünglichen Annahme bereits vor diesem Bump gelesen
+(`divergent_files`/`migrate status`), und die Migrationskette war ursprünglich falsch begründet
+- sie kann nur aus dem *neuen* Baum kommen, nicht durch eine andere Abfragereihenfolge aus der
+alten Instanz. 24 neue Tests unter `test_dist_upgrade.py` decken die Klassifikation, alle
+Abbruchgründe, `--keep-local`, `--prune` und beide Quellformen (Verzeichnis und Tarball,
+inklusive der sha256- und Top-Level-Prüfung) ab.
+
+Bewusst nicht angetastet: `instructions/private-instance.md` (der Clone-Weg ändert sich nicht,
+`INSTALL.md` benennt jetzt beide Wege nebeneinander) und die Frage, wie `dist upgrade` mit
+Collection-Templates umgeht, deren Namen eine fremde Instanz gar nicht hat - es verhält sich wie
+`upstream merge` und schreibt sie, was ein eigenes Issue gegen den Export wäre, keins gegen das
+Upgrade.
+
+**Sechster Bump: die ungeprüfte Phase nachgeholt.** Der Abschluss des vorigen Bumps lief auf
+Sonnet, und `stack-dev` Schritt 6 verlangt dort genau zwei Dinge, die kein Check erzwingt:
+Issue-Body und `docs/`-Veralterung. Der Body war gemacht, die `docs/`-Prüfung nicht - sie wurde
+benannt statt durchgeführt. Nachgeholt auf Opus, mit einem Fund.
+
+`docs/ownership-and-templates.md` § „The consequence in practice" beschrieb ein Upgrade als
+Zweiteilung: verbatim überschreiben, `.template`-gestützte Dateien liegen lassen - und begründete
+den ersten Teil damit, dass verbatim ausgelieferte Dateien „safe to replace wholesale" seien,
+weil sie „never instance-specific to begin with" waren. Genau diese Annahme trifft `dist upgrade`
+nicht: eine Instanz *kann* eine verbatim ausgelieferte Datei angefasst haben, und die sha256 je
+Datei existiert, um das zu erkennen, statt es vorauszusetzen. Dazu fehlte die dritte Klasse ganz -
+die einmalig gesäten, danach instanzeigenen Pfade (`.wikitool-kb.json`, `CHANGES.md`,
+`kb/log.md`, `raw/*/.gitkeep`), die im Stamp stehen wie jede andere Datei und deshalb aktiv
+ausgeschlossen werden müssen. Die Seite nennt jetzt drei Klassen und die engere praktische Regel:
+überschreibe die verbatim ausgelieferten Dateien, *die diese Instanz nicht angefasst hat*.
+
+Dazu eine Präzisierung in `tools/CONTRACT.md`, die vorher nirgends stand: nach `--keep-local`
+wird der neue Stamp trotzdem vollständig geschrieben, trägt also die Release-Summe auch für
+Dateien, die bewusst *nicht* geschrieben wurden. Der Stamp ist die Vergleichsbasis für den
+nächsten Lauf, kein wörtliches Inventar der Platte - und genau das hält eine übersprungene Datei
+bei jedem weiteren Lauf als abweichend gemeldet, statt sie nach einmaligem Überspringen still als
+aktuell zu führen.
+
+---
+
 ## 4.4.0 - 2026-09-03 - Versionskandidat statt Bump-pro-Release: VERSION traegt -beta.N, version release fixiert
 
 **Author:** Torben Nehmer
@@ -43,12 +242,14 @@ dev-checkout concern - readable here, never shipped as something to parse.
 - Versionskandidat statt Bump-pro-Release: VERSION traegt -beta.N, version release fixiert
 <!-- /wikitool:bumps -->
 
-Bisher bekam jeder `version bump` sofort eine fixierte, dauerhafte Nummer, unabhängig davon, ob
+Bisher bekam jeder `version bump` sofort eine fixierte Nummer, und weil `release.yml` auf jede
-je ein Release dazu erschien - fünf Minor-Bumps ohne Release ergaben fünf Nummern, von denen vier
+`VERSION`-Bewegung feuert, wurde daraus sofort ein Release: Nummern entstanden in
-nie ausgeliefert wurden. `VERSION` trägt jetzt zwischen zwei Releases **einen** laufenden
+Commit-Granularität statt in Release-Granularität. Der 2026-09-03 hat so vier Releases in sechs
-Kandidaten (`X.Y.Z-beta.N`) statt einer neuen Nummer pro Bump: `--major/--minor/--patch`
+Stunden erzeugt (`4.3.0` bis `4.3.3`), zwei davon für reine Prosa-Änderungen - alle vier echt,
-eskaliert diesen Kandidaten max-wins gegen den letzten Release, statt daneben eine neue Nummer zu
+keines davon eine Einheit, an der ein Konsument sich hätte orientieren können. `VERSION` trägt
-schreiben, und schrittet dabei nie zurück.
+jetzt zwischen zwei Releases **einen** laufenden Kandidaten (`X.Y.Z-beta.N`):
+`--major/--minor/--patch` eskaliert diesen Kandidaten max-wins gegen den letzten Release, statt
+eine neue Nummer danebenzustellen, und geht dabei nie zurück.
 
 `Version` versteht den Suffix, mit einer expliziten Ordnung
 (`4.4.0-beta.1 < 4.4.0-beta.2 < 4.4.0`, numerisch nach `N`, nicht lexikografisch). `CHANGES.md`

DEVELOPMENT.md

@@ -71,15 +71,13 @@ eine Sitzung ihn tatsächlich durchläuft:
    lädt Tarball plus Prüfsumme hoch. **CI setzt den Tag, nie eine Sitzung** - das hält
    Invariante 5 intakt.
 
-## Verify-Befehle im Überblick
+Die drei Verify-Befehle stehen oben in Schritt 3; was jeder von ihnen prüft, steht in
-
+[tools/CONTRACT.md](tools/CONTRACT.md) und wird dort von `docs verify` gegen die tatsächliche
-| Befehl | Prüft |
+CLI gehalten. Hier steht es bewusst **nicht** noch einmal: eine zweite Beschreibung derselben
-|---|---|
+Befehle ist genau die Kopie, die driftet (AGENTS.md Invariante 8), und dieses Dokument liegt
-| `cd tools && .venv/bin/python -m pytest -q` | Die gesamte Testsuite, hermetisch gegen eine leere Maschine (siehe `instructions/dev/testing-conventions.md`) |
+außerhalb der Dateien, die der Kommandotabellen-Check von `docs verify` abdeckt - hier fällt eine
-| `tools/wikitool docs verify` | CLI-Kommandotabelle, Contract-Präsenz, Type-Drift, `.gitignore`-Kanarienvögel, `VERSION`/`CHANGES.md`-Übereinstimmung, Grenzübertritts-Dokumentation |
+Drift also niemandem auf. Was `pytest` an dieser Stelle vom Entwickler erwartet, steht in
-| `tools/wikitool instructions verify` | Jede Instruction und jeder Skill unter `instructions/`, verwaiste Dateien, `instructions/dev/`-Referenzen von außerhalb |
+[instructions/dev/testing-conventions.md](instructions/dev/testing-conventions.md).
-
-Die volle Kommandoreferenz inklusive Fehlerkontrakt: [tools/CONTRACT.md](tools/CONTRACT.md).
 
 ## Die CI-Hälfte
 

INSTALL.md

@@ -167,10 +167,17 @@ wenn nicht). `tools/wikitool version notes` druckt den Eintrag.
 
 ### Eine Instanz aktualisieren
 
-Das Anwenden eines Updates ist ein bewusst manueller Vorgang - es schreibt in eine Instanz, die
+Zwei Wege, je nachdem, wie diese Instanz entstanden ist. Ein **Clone mit gemeinsamer
-bereits Inhalt hat. Der Inhalt hat dabei eine **eigene Version**: `.wikitool-kb.json` sagt, in
+Git-History** (`upstream`-Remote auf das Ursprungs-Repo, siehe
-welcher Form die Seiten vorliegen, unabhängig davon, welche Maschinerie danebensteht. Genau
+[instructions/private-instance.md](instructions/private-instance.md)) nimmt Stack-Updates per
-dieser Unterschied ist der Zustand, in dem sich jede Instanz mitten im Upgrade befindet.
+echtem Drei-Wege-Merge: `tools/wikitool upstream merge`. Alles Folgende gilt für eine **Instanz
+aus einem Tarball**, ohne gemeinsame History - der Weg unten unter „Eine Instanz aktualisieren"
+nutzt sie.
+
+Das Anwenden eines Updates schreibt in eine Instanz, die bereits Inhalt hat. Der Inhalt hat dabei
+eine **eigene Version**: `.wikitool-kb.json` sagt, in welcher Form die Seiten vorliegen,
+unabhängig davon, welche Maschinerie danebensteht. Genau dieser Unterschied ist der Zustand, in
+dem sich jede Instanz mitten im Upgrade befindet.
 
 1. **Vor dem Tausch** prüfen, was ansteht - solange `VERSION` noch die alte ist:
 
@@ -178,19 +185,35 @@ dieser Unterschied ist der Zustand, in dem sich jede Instanz mitten im Upgrade b
    tools/wikitool migrate status
    ```
 
-2. Release-Tarball herunterladen und entpacken (Weg A), die Release-Notes lesen.
+   Steht hier etwas aus, erst diese Migrationskette abschließen (Schritt 5 unten) - `dist upgrade`
-3. Die **Maschinerie** aus dem Tarball über die Instanz kopieren: `tools/`, `types/`,
+   verweigert den Tausch sonst von selbst.
-   `instructions/`, `AGENTS.md`, `VERSION`, `.wikitool-release.json` - **und `kb/CONTRACT.md`**.
+
-   Die letzte Datei liegt unter einem Content-Verzeichnis, ist aber Stack-Eigentum: sie hält,
+2. Release-Tarball herunterladen und die Release-Notes lesen (Weg A oben).
-   was `wikitool` erzwingt, und ist in jeder Instanz gleich. Nicht anfassen: alles andere unter
+3. **Maschinerie tauschen:**
-   `kb/` und `raw/`, `work/`, `.wikitool-kb.json` und `.git/` - das ist die Instanz selbst,
+
-   `kb/CONVENTIONS.md` und die `kb/*/COLLECTION.md` eingeschlossen.
+   ```bash
-4. Achtung bei lokal angepassten Stack-Dateien. Die Autorenkonventionen gehören **nicht** dazu:
+   tools/wikitool dist upgrade <tarball-oder-verzeichnis> --dry-run
-   `kb/CONVENTIONS.md` und die `kb/*/COLLECTION.md` liegen unter `kb/`, werden in Schritt 3
+   ```
-   also ohnehin nicht angefasst - genau dafür ist der Schnitt da. Wer darüber hinaus etwas
+
-   unter `tools/`, `types/` oder `instructions/` verändert hat, sichert das vorher und spielt
+   Klassifiziert jede Datei aus dem `files`-Block der neuen `.wikitool-release.json`:
-   es danach wieder ein. Welche Dateien das sind, verrät ein Vergleich gegen die sha256-Summen
+   unverändert seit der Installation, lokal verändert oder gelöscht, neu im Release, oder aus dem
-   im `files`-Block der alten `.wikitool-release.json`.
+   Release entfallen - und druckt die Migrationskette, die nach dem Tausch aussteht, ohne sie
+   auszuführen. Ohne `--dry-run` schreibt der Befehl; eine lokal veränderte oder gelöschte Datei
+   wird dabei **nie** stillschweigend überschrieben - der Lauf bricht mit der vollständigen Liste
+   ab, es sei denn `--keep-local` ist gesetzt (dann bleibt jede davon unangetastet, erneut
+   gemeldet). `--prune` entfernt zusätzlich Dateien, die der neue Release nicht mehr ausliefert
+   und die seit der Installation unverändert sind. Voraussetzungen: ein sauberer Arbeitsbaum
+   (kein Git-Repo ist ein WARN, keine Sperre), eine lokale `.wikitool-release.json` mit
+   `files`-Block (fehlt sie, siehe „Fallstricke" unten), und `.wikitool-kb.json` vorhanden.
+   Committet und pusht nichts (Invariante 5). Vollständiger Fehlerkontrakt:
+   [tools/CONTRACT.md](tools/CONTRACT.md).
+
+   Eine lokal veränderte Stack-Datei ist damit sichtbar, statt von Hand gegen die sha256-Summen
+   im `files`-Block geprüft werden zu müssen - genau der Schritt, der vor `4.5.0` hier stand.
+4. Bei einer Kompatibilitätsgrenze (`dist upgrade` meldet sie laut) die Release-Notes vor dem
+   nächsten Schritt lesen: **Breaking Change:** und **Migration:** im Eintrag von
+   `tools/wikitool version notes` sagen, was aufhört zu funktionieren und ob der Korpus
+   umgeschrieben werden muss.
 5. **Die Migrationskette abarbeiten.** `tools/wikitool migrate status` listet jetzt alle
    offenen Migrationen in der Reihenfolge, in der sie laufen müssen - bei einem Sprung über
    mehrere Versionen sind das mehrere. Für jede: das genannte Dokument unter
@@ -204,15 +227,30 @@ dieser Unterschied ist der Zustand, in dem sich jede Instanz mitten im Upgrade b
    `done` verweigert jede Version, die nicht das nächste Glied ist - eine übersprungene
    Migration hinterlässt einen Korpus in einer Form, die keine Version beschreibt. Ein
    abgebrochenes Upgrade wird durch erneutes `migrate status` fortgesetzt.
-6. Prüfen: `tools/wikitool migrate verify --from <commit vor der Migration>`, dann `doctor`,
+6. Prüfen: `tools/wikitool migrate verify --from <commit vor dem Tausch>`, dann `doctor`,
    `docs verify`, `instructions verify` und `lint`. Zum Schluss
    `tools/wikitool instructions sync` (die Skills sind Kopien) und die Agent-Session neu
-   starten.
+   starten. `dist upgrade` nennt diese Reihenfolge im eigenen Abschlussbericht, führt aber keinen
+   der Schritte selbst aus.
 
 `doctor` warnt, solange `kb_version` hinter `VERSION` zurückliegt und noch Migrationen offen
 sind. Einer Instanz, die älter ist als `.wikitool-kb.json`, fehlt die Datei ganz - dann einmalig
 `tools/wikitool migrate baseline <version>` aufrufen; geraten wird nichts.
 
+**Fallstricke.** Eine Instanz ohne lokale `.wikitool-release.json` (oder eine ohne `files`-Block,
+aus der Zeit vor `4.5.0`) hat für `dist upgrade` keine Basis, gegen die es eine lokale Änderung
+erkennen könnte, und verweigert den Tausch - dafür gibt es heute keine Reparatur (siehe Gitea #7).
+Der Befehl lädt selbst nichts herunter: `<tarball-oder-verzeichnis>` muss vorher aus Weg A
+geholt werden, und ein Tarball muss genau ein Top-Level-Verzeichnis enthalten - die Form, in der
+`.gitea/workflows/release.yml` es baut.
+
+Vor `4.5.0` stand hier ein rein manueller Ablauf (Maschinerie von Hand kopieren, `kb/CONTRACT.md`
+eingeschlossen, sha256-Vergleich von Hand). `dist upgrade` ersetzt genau diesen Teil; wer ihn
+dennoch von Hand nachvollziehen will oder muss (ein Werkzeug, das `wikitool` selbst nicht
+ausführen kann), findet die Dateiliste im `files`-Block der `.wikitool-release.json` und die
+Ausnahmen (`kb/CONVENTIONS.md`, `kb/*/COLLECTION.md`, `.wikitool-kb.json`) in
+[tools/CONTRACT.md](tools/CONTRACT.md)s `dist upgrade`-Zeile.
+
 ### Sonderfall: Update von 1.x auf 2.0.0
 
 Mit `2.0.0` wurde das Ursprungs-Repo von `torben/llm-wiki-test1` auf `torben/chemenu`

VERSION

@@ -1 +1 @@
-4.4.0
+4.5.0

docs/ownership-and-templates.md

@@ -4,7 +4,8 @@ Chemenu ships two kinds of files side by side, and at a glance they look the sam
 plain markdown, both sit in the repo root or under `kb/`, both get read at session start. But a
 stack upgrade treats them completely differently. Some - [AGENTS.md](../AGENTS.md),
 [kb/CONTRACT.md](../kb/CONTRACT.md), the per-stage contracts - are identical in every instance
-that runs this stack and can simply be overwritten by the next release. Others - `USER.md`,
+that runs this stack and are the next release's to replace (with one caveat about local edits,
+below). Others - `USER.md`,
 `SOUL.md`, `kb/CONVENTIONS.md`, `ENVIRONMENT.md` - describe one particular instance, and
 overwriting them would silently erase a choice someone made on purpose.
 
@@ -42,6 +43,25 @@ Keeping the boundary at the file level, rather than trying to merge changes with
 file, means an upgrade never has to guess which lines are "stack" and which are "instance" -
 the file itself already answers that.
 
+## Why the boundary is a predicate rather than a list
+
+For a while the boundary was written down as a list of paths - once in `dist_cmd.py`, once in
+the merge procedure a private instance was told to run by hand, and once in the check that
+procedure ended with. Three copies of one fact, which is the shape [AGENTS.md](../AGENTS.md)
+invariant 8 exists to forbid, and they drifted exactly as predicted: the hand-run procedure was
+still naming three paths after the collection contracts had moved to the instance's side of the
+line, so it discarded upstream changes to files it had never heard of, while its own final check
+excluded the same three paths and therefore reported success.
+
+`chemenu/ownership.py` replaced the lists with one question - is this path, under a content
+stage, the stack's or the instance's? - answered by shape rather than by enumeration:
+`<stage>/CONTRACT.md`, and anything ending `.template`. Both consumers ask it, so `dist export`
+and `wikitool upstream merge` cannot disagree, and a machinery file added under a content stage
+tomorrow is recognised by both without either being edited. The deeper point is not the
+deduplication: a list has to be maintained by whoever remembers it exists, and the failure mode
+when nobody does is silence, because a path the list has never heard of simply looks like
+content.
+
 ## Why a `.template`, not just an absent file
 
 The mechanism for instance-owned content is a `.template` file the distribution ships instead
@@ -63,9 +83,33 @@ state rather than a sign setup was skipped.
 
 ## The consequence in practice
 
-Running a stack upgrade against an existing instance boils down to: overwrite the verbatim
+An upgrade sorts every shipped path into three categories, not two - and the third one only
-files, leave the `.template`-sourced files alone. The verbatim files are safe to replace
+becomes visible once an upgrade is a command rather than a hand-run copy:
-wholesale because they were never instance-specific to begin with - identical content going
+
-back in changes nothing an instance actually decided. The template-sourced files were filled in
+- **Verbatim files** - `AGENTS.md`, `kb/CONTRACT.md`, the per-stage contracts, everything under
-once, by a person, for a reason, and nothing about a newer release of the stack's mechanics
+  `tools/`, `types/` and `instructions/` - are the release's to replace.
-gives it standing to override that.
+- **`.template`-sourced files** - `USER.md`, `SOUL.md`, `kb/CONVENTIONS.md`, each
+  `kb/<name>/COLLECTION.md`, `ENVIRONMENT.md`, the `root: kb` type-specs - are never written by
+  an upgrade at all. The distribution ships only the `.template` beside them, so the filled file
+  is out of reach by construction rather than by a rule someone has to remember.
+- **Seeded-once files** - `.wikitool-kb.json`, `CHANGES.md`, `kb/log.md`, `raw/*/.gitkeep` - are
+  written into a *new* instance by `dist export` and belong to the instance from then on. They
+  are the awkward category: they sit in the release stamp's file list like any other shipped
+  file, so an upgrade has to exclude them deliberately (`chemenu.ownership.is_export_stub` and
+  `is_upgrade_preserved`). An upgrade that re-seeded them would reset the record of which
+  migrations ran, or erase the changelog the instance wrote for itself.
+
+The first category carries a caveat that the word "verbatim" hides. It says who *decides* the
+content, not that overwriting is always safe: an instance can still have edited a verbatim file
+- a patched `tools/`, a locally adjusted instruction - and an upgrade assuming otherwise would
+destroy that silently. Avoiding that assumption is the whole reason `dist export` records a
+sha256 per shipped file in `.wikitool-release.json`. `wikitool dist upgrade` compares every
+candidate path against the digest recorded when it was installed, overwrites only what still
+matches, and refuses rather than overwrite what does not.
+
+So the practical rule is narrower than "overwrite the verbatim files, leave the rest alone":
+overwrite the verbatim files *this instance has not touched*, never write the other two
+categories, and make a locally changed file a decision someone takes deliberately instead of
+one an upgrade takes for them. The template-sourced files were filled in once, by a person, for
+a reason, and nothing about a newer release of the stack's mechanics gives it standing to
+override that.

docs/version-model.md

@@ -83,22 +83,27 @@ matter just as much in practice: how many numbers get handed out along the way t
 release. For a while the answer was "one per bump," and that turned out to be the wrong grain
 entirely.
 
-The two things that actually consume a version number are a release and CI's version gate - and
+Two mechanisms decide when a number gets minted, and they answer different questions. CI's
-they disagree about granularity. The gate wants `VERSION` to move on every push that touches
+version gate asks a *commit*-level one: has this tree changed since the last push, and if so
-stack-shaped paths, which is a *commit*-level question: has this tree changed since the last
+has `VERSION` moved with it. A release asks something else entirely: is this a state worth
-push. A release wants to know something else: has *this specific number* been published, ever.
+handing to someone, under a number they will pin against. Tying the second to the first - every
-Handing out a fresh number per bump answers the gate's question by accident and the release's
+`VERSION` move firing the release workflow - answers the gate correctly and the release question
-question wrongly - it treats every bump as if it were about to ship, when most of them are steps
+by accident, because it treats every bump as if it were about to ship when most bumps are steps
-toward a release that hasn't happened yet. Four bumps in one session, on the same day, for the
+toward a release that has not happened yet.
-same eventual release, produced four numbers that a version-check feed would have reported as
+
-four different available upgrades, three of which were never real.
+The failure mode is not phantom numbers; every one of those releases was real, tagged and
+downloadable. It is that "real" stopped meaning anything. On 2026-09-03 this repository cut four
+releases in six hours - `4.3.0` through `4.3.3` - for one continuous arc of work, two of them for
+prose changes alone. Someone tracking the feed saw four upgrades and had no way to tell which, if
+any, was a moment worth stopping for. A release is a promise addressed to a consumer, and a
+promise made four times an afternoon is not a smaller promise, it is a less legible one.
 
 The fix is not to slow the gate down - it still wants `VERSION` to move every time, and it still
-gets that. It's to stop treating every movement as a new number. Between two releases the stack
+gets that. It is to stop treating every movement as a number worth publishing. Between two
-now carries one running candidate, escalating through `-beta.N` as bumps accumulate, and only
+releases the stack now carries one running candidate, escalating through `-beta.N` as bumps
-`version release` spends the number for real by fixing it and closing its changelog entry. A
+accumulate, and only `version release` spends the number for real by fixing it and closing its
-number is proposed by a bump and consumed by a release; conflating the two was the actual defect,
+changelog entry. A number is proposed by a bump and spent by a release; conflating the two was
-not the arithmetic of any single bump.
+the actual defect, not the arithmetic of any single bump.
 
 This is also why a candidate never gets to a distributed instance. The promise a released version
 makes - "install this, and it is exactly what its number says" - has no equivalent for something

instructions/dev/version-parts.md

@@ -9,7 +9,7 @@ Two questions decide a version bump, and they are **not the same question**:
 
 1. **Is the new version a drop-in replacement for the old one?** This is what the version
    number itself says. Compatibility is read off the **leftmost non-zero component** - on this
-   stack (`2.x`) that is MAJOR, on a `0.x` stack it is MINOR. A bump that changes it is called
+   stack (`4.x`) that is MAJOR, on a `0.x` stack it is MINOR. A bump that changes it is called
    *boundary-crossing* below, because that is the term `version bump` and `docs verify` use in
    their own messages.
 2. **Must existing content be migrated?** This is a *consequence* a boundary crossing may or
@@ -23,11 +23,13 @@ already (see the case study at the end), which is why this file exists.
 ## The candidate model
 
 Between two releases the stack carries **one running candidate**, not a fresh version per
-`bump`. Five bumps with no release in between used to mean five numbers, four of which nothing
+`bump`. Before that, every bump minted a number *and* a release: CI's version gate requires
-ever consumed - the release-granularity CI's version gate wants (`VERSION` must move on every
+`VERSION` to move on every stack-touching push, and `release.yml` fires on every `VERSION`
-stack-touching push) was being paid at bump granularity instead. A candidate closes that gap
+move, so releases were being cut at commit granularity. 2026-09-03 produced four of them in
-without touching the gate: `VERSION` still moves on every bump, it just escalates the *same*
+six hours (`4.3.0` through `4.3.3`) for one arc of work - all four real, none of them a
-number instead of handing out a new one.
+meaningful unit to anyone downstream. A candidate closes that gap without touching the gate:
+`VERSION` still moves on every bump, it just escalates the *same* number instead of handing out
+a new one, and only `version release` turns it into something the release workflow acts on.
 
 - **State lives in `VERSION` itself**, as an optional `-beta.N` suffix (`4.4.0-beta.3`). No
   second state file: the last release is read back out of `CHANGES.md` (the newest entry with no
@@ -35,8 +37,8 @@ number instead of handing out a new one.
   release - derived, not stored.
 - **`--major`/`--minor`/`--patch` is max-wins escalation**, not a step you can undo. A `--patch`
   bump on a candidate already at MINOR only advances its bump count (`N`); nothing ever steps a
-  candidate back down. Declaring the part is still your judgment call, made the same way section
+  candidate back down. Declaring the part is still your judgment call, made the same way the
-  below describes - `escalate()` only ever raises it further.
+  steps below describe - `escalate()` only ever raises it further.
 - **A candidate is never released.** Pre-release is a dev-checkout state; `release.yml` only acts
   on a suffix-free `VERSION`, so a distributed instance never sees a `-beta.` version at all, and
   its parser never has to know the suffix exists.

instructions/gates.md

@@ -103,6 +103,26 @@ The setup this gate exists for - a private instance that takes stack updates fro
 upstream - is [private-instance.md](private-instance.md). Step 4 there arms it, deliberately
 *before* the first `publish`: added afterwards it leaves open exactly the window it closes.
 
+### Mass-Update Gate blind spot: `upstream merge`
+
+`upstream merge` (a private instance taking a stack update - see
+[private-instance.md](private-instance.md)) can update or delete dozens of stack-owned paths in
+one commit, and the Mass-Update Gate does not see any of it. The gate counts *working-tree*
+changes before `publish` stages them; by the time `upstream merge` commits, the change is
+already history, and the commit it made is not what a later `publish` would be staging - that
+publish sees only whatever this session adds on top. A merge touching 200 files therefore goes
+out ungated the moment it is pushed.
+
+This is not a hole to patch by making `upstream merge` route through the gate: the gate's
+question ("is this too much to publish?") does not apply to a change that only ever touches
+stack-owned paths that are, by definition, not this instance's own content. The check that
+actually matters here is `upstream merge`'s own postcheck - it re-verifies the merge commit
+against `upstream verify`'s logic immediately after committing, and exits 1 with the offending
+paths if anything landed outside a stack-owned one. **The merge commit is deliberately left in
+place** rather than reverted: it exists, a human has to look at it, and a command that quietly
+repaired its own mistake would hide the one event worth seeing. That postcheck is the safeguard
+for this command, not the Mass-Update Gate.
+
 ## Iteration Budget Gate and loop-breaker
 
 Every `wikitool` call is counted per session. Calls are refused past **60 in a session**, or

instructions/private-instance.md

@@ -108,69 +108,53 @@ So the merge has to be scoped. That is the procedure below, and it is not option
 
 ## Taking a stack update
 
-Take the machinery, never the content. The merge is held open, the content stages are forced
+```bash
-back to your own state, and only then does it close.
+tools/wikitool upstream merge --remote upstream --branch main
+```
 
-**Three files under those stages are machinery, not content**, and forcing them back is how an
+Take the machinery, never the content. This is the command form of the same idea a hand-rolled
-upstream contract change gets silently discarded:
+merge would need: hold the merge open, force the content stages back to your own state, restore
+only the paths that are machinery, and only then let it close. Which paths those are is not a
+short literal list any more (see below) - it is `chemenu.ownership.is_stack_owned`, the same
+predicate `dist_cmd.py`'s export reads, so a stack change that adds a new machinery path under a
+content stage is recognised automatically rather than needing this document edited first.
 
-| Path | Why it must take the upstream side |
+**What counts as machinery under a content stage**, for readers who want the shape rather than
+the code:
+
+| Path | Why it takes the upstream side |
 |---|---|
-| `kb/CONTRACT.md` | The stack's own knowledge-layer contract. Every rule in it is enforced by `wikitool`; an instance never edits it |
+| `<stage>/CONTRACT.md` (`kb/CONTRACT.md`, `raw/CONTRACT.md`, `work/CONTRACT.md`, `reports/CONTRACT.md`) | The stack's own stage contract. Every rule in it is enforced by `wikitool`; an instance never edits it |
-| `kb/CONVENTIONS.md.template` | The template your `kb/CONVENTIONS.md` was filled from. The filled file is yours; the template is the stack's |
+| any `*.template` under a content stage (`kb/CONVENTIONS.md.template`, each `kb/<name>/COLLECTION.md.template`, and any later one) | The template your filled file was adopted from. The filled file is yours; the template is the stack's |
-| `raw/CONTRACT.md` | The raw stage's contract, for the same reason as the first row |
 
-Everything else under `kb/` and `raw/` is yours, `kb/CONVENTIONS.md` and each
+Everything else under `kb/`, `raw/`, `work/` and `reports/` is yours, `kb/CONVENTIONS.md` and
-`kb/<name>/COLLECTION.md` included - they bind your corpus, and they are exactly what the
+each `kb/<name>/COLLECTION.md` included - they bind your corpus, and they are exactly what
-restore below is protecting.
+`upstream merge` protects.
 
-```bash
+**Your local, uncommitted-by-design files under those stages survive.** Forcing a content stage
-BEFORE=$(git rev-parse HEAD)
+back to your own state removes only what git tracks, never the directory wholesale - which
-git fetch upstream
+matters because `reports/` is gitignored apart from its contract, so it holds data that is in no
+commit and cannot be recomputed: the telemetry traces `eval score` reads, saved eval reports,
+past lint reports. A merge has no business touching any of it, and does not.
 
-# --no-commit holds the merge open; it may report conflicts under kb/ or raw/,
+The command itself checks its own result the same way `upstream verify` would, immediately
-# which the next four lines are about to make irrelevant.
+after committing, and refuses loudly - without rolling the commit back - if anything landed
-git merge --no-commit --no-ff upstream/main || true
+outside a stack-owned path. A refusal there is a bug report, not something to work around by
-
+hand; see [tools/CONTRACT.md](../tools/CONTRACT.md) for the full error contract, including what
-# Whatever the merge did to the content stages, undo it. HEAD is still your
+a real conflict in `tools/`/`types/`/`instructions/` leaves behind.
-# pre-merge commit while the merge is open, so this restores exactly your side.
-git rm -rq --cached --ignore-unmatch kb raw
-rm -rf kb raw
-git checkout HEAD -- kb raw
-
-# ...then take the upstream side back for the machinery that lives among it.
-# MERGE_HEAD is still resolvable while the merge is open.
-git checkout MERGE_HEAD -- kb/CONTRACT.md kb/CONVENTIONS.md.template raw/CONTRACT.md
-
-git commit --no-edit
-```
-
-Then **check that it worked**, rather than trusting that it did. The same three paths are
-excluded here, spelled out rather than held in a variable so that the check can be read on its
-own and copied on its own:
-
-```bash
-git diff --name-only "$BEFORE" HEAD -- kb raw \
-  | grep -vE '^(kb/CONTRACT\.md|kb/CONVENTIONS\.md\.template|raw/CONTRACT\.md)$'
-```
-
-Must print nothing.
-
-An empty result is the proof that the update touched machinery only. A non-empty one means a
-path slipped through - inspect it before going further.
-
-**The exclusion is not cosmetic.** Without it the check reports *empty* for an update that just
-ate a `kb/CONTRACT.md` change - it would be confirming the failure it exists to catch. If one of
-the three paths does not appear in the diff at all, that is fine: it means upstream did not
-touch it.
 
 Then, as after any stack change: `doctor`, `docs verify`, `instructions verify`, `migrate status`,
 `lint`. A `migrate status` with outstanding links means the update crossed a compatibility
 boundary - follow [migrate-corpus.md](migrate-corpus.md) before doing anything else.
 
-**Why not just `git merge upstream/main`?** Because of the table above: a page the upstream
+**Why not just `git merge upstream/main`?** A page the upstream *adds* arrives with no conflict
-*adds* arrives with no conflict and no message. You would find out when `lint` starts reporting
+and no message under a plain merge - measured in the table further up this document. You would
-pages you never wrote - if you noticed at all.
+find out when `lint` starts reporting pages you never wrote, if you noticed at all. `upstream
+merge` closes exactly that gap: the content stages never see the upstream's version at all.
+
+**Checking a merge you resolved by hand instead** (or auditing a past one): `tools/wikitool
+upstream verify --since <rev-before> --until <rev-after>` runs the same check `upstream merge`
+runs on itself, without doing the merge.
 
 ## Where stack development happens
 
@@ -186,17 +170,21 @@ merge above. Nothing is lost by the detour: the fix has to pass that CI either w
 
 ## Decision points
 
-- **Merge conflict in `kb/` or `raw/`?** Expected, and already handled: the update procedure
+- **Merge conflict in `kb/`, `raw/`, `work/` or `reports/`?** Expected, and already handled:
-  above overwrites those stages with your own afterwards, so the conflict resolves itself.
+  `upstream merge` overwrites those stages with your own afterwards, so the conflict resolves
-  Never resolve one by hand with `git add -A` - that is exactly how the upstream version, which
+  itself. Never resolve one by hand with `git add -A` in a merge you are running yourself
-  git left sitting in your working tree, gets committed into your instance.
+  instead - that is exactly how the upstream version, which git left sitting in your working
-- **`git diff` after the merge shows something under `kb/` or `raw/`?** Stop - unless it is one
+  tree, gets committed into your instance.
-  of the three machinery paths the check excludes, which is the update working as intended. For
+- **`upstream merge` exits 1 after committing?** Read the message: its own postcheck found
-  anything else the scoping step did not take: do not publish; find out which path came through
+  content outside a stack-owned path in the commit it just made. The commit is **not** rolled
-  and where from.
+  back - inspect it (`git show`, or `tools/wikitool upstream verify --since <before> --until
+  HEAD`) and decide by hand whether to revert it, fix forward, or report it as a stack bug. This
+  should not happen; if it does, `chemenu.ownership.is_stack_owned` disagreed with itself between
+  the restore and the check, which is exactly what the shared predicate is meant to prevent.
 - **Conflict in `tools/`, `types/` or `instructions/`?** You changed the stack locally, which
-  step "Where stack development happens" says not to do. Take the upstream side and re-file the
+  step "Where stack development happens" says not to do. `upstream merge` leaves the merge open
-  change as an issue there.
+  rather than guessing - take the upstream side for the named paths and re-file the change as an
+  issue there, or resolve deliberately and finish the commit yourself.
 - **...but you changed how *your pages* are written?** That is not a stack change and the rule
   above does not apply to it. Language, section headings, naming forms, tone, relationship
   labels and the confidence rubric live in `kb/CONVENTIONS.md`, and each collection's authoring

tools/CONTRACT.md

@@ -72,6 +72,7 @@ tools/wikitool <command> --help
 | `eval sessions [--json]` | List the sessions that have a trace under `reports/telemetry/`, most recent first. Read-only and exempt from the Iteration Budget Gate |
 | `eval score [--session <id>] [--json] [--markdown out.md] [--save] [--fail-on-error]` | Score one traced session: structural state from `lint`'s own checks (L1) plus trajectory rules over the trace (L2) - was a refused call repeated unchanged, was a gate flag passed without that gate having refused anything, did a publish of `kb/` pages go unlogged. Defaults to the current session. `--save` writes `reports/evals/<date>/<session>.{json,md}`. Read-only over `kb/` and exempt from the budget; see [../EVALS.md](../EVALS.md) |
 | `dist export <target> [--dry-run] [--source-repo U] [--source-commit SHA] [--release-url U] [--update-url U]` | Write a contentless, distributable copy of this repo's machinery into an empty `<target>` directory: `AGENTS.md`/`README.md`/`EVALS.md` with any `<!-- dist:strip-start -->...<!-- dist:strip-end -->` region removed, `instructions/` (minus `instructions/dev/`), `types/` (the `root: kb` page type-specs and their schemas re-keyed as `.template`, the stack's own verbatim), `docs/` verbatim, `tools/` (no venv/caches), the `.github/hooks/`+`.vibe/` session-tracing config plus `.claude/settings.json`, `kb/CONTRACT.md` (no pages, no areas), empty `raw/{articles,documents,notes,assets}/`, `VERSION`, `USER.md.template`/`SOUL.md.template` plus `kb/CONVENTIONS.md.template` and each collection's contract re-keyed as `kb/<name>/COLLECTION.md.template` (the templates ship; the filled `USER.md`/`SOUL.md`/`kb/CONVENTIONS.md`/`kb/<name>/COLLECTION.md`/`types/<page-type>.md` never do - all of them bind their instance and none are the stack's to decide, and `find_leaks` refuses a plan carrying one), and a generated `.wikitool-release.json` stamp (version, export date, origin, and a sha256 per exported file - the base a later upgrade would compare against). The four origin options only fill stamp fields: `export` never calls git and cannot discover them. Refuses a non-empty target, and a tree with no `VERSION`. See `instructions/setup-instance.md`. One-way: there is no command that reconstructs a distributed instance into a dev instance - work on the stack in the origin repo (or a new dev instance exported from it) instead |
+| `dist upgrade <source> [--dry-run] [--keep-local] [--prune] [--pre]` | Apply a stack update `dist export` produced - the write half of `version check`. Never downloads anything: `<source>` is an already-fetched export directory or `.tar.gz` release archive (verified against a sibling `.sha256` if one is present; WARNs, does not block, if it is absent), which must unpack to exactly one top-level directory - the shape `.gitea/workflows/release.yml` packs. The write set is exactly the *new* `.wikitool-release.json`'s `files` block, minus what an export re-seeds from a blank template every time (`kb/log.md`, `raw/*/.gitkeep` - `chemenu.ownership.is_export_stub`) or seeds once and the instance owns from then on (`.wikitool-kb.json`, `CHANGES.md` - `chemenu.ownership.is_upgrade_preserved`), plus the stamp itself, always rewritten. Every candidate path is classified against the *local* `.wikitool-release.json`'s recorded digest for it: unchanged is overwritten silently, absent from the old stamp is created, and locally modified or locally deleted is **never** silently overwritten - the run aborts with the full list unless `--keep-local` says to proceed and leave every one of them untouched. After a `--keep-local` run the new stamp is still written whole, so it records the release's digest for files that were deliberately *not* written: the stamp is the baseline for the next comparison, not a literal inventory of what is on disk. That is what keeps a skipped file diverging - and therefore reported - on every later run, rather than quietly reading as current once it has been skipped once. A path in the old stamp but not the new one is reported as no longer part of the release and left alone unless `--prune` is passed, which removes it only if it is still unchanged since installation. Reports the migration chain the new machinery would owe (`chemenu.kb_state.chain` over the *new* tree's `instructions/migrations/`, read via a `directory` argument to `load_migrations`) but never runs any of it - there is no `migrate run`. Refuses before touching the source at all when: `VERSION` or `.wikitool-release.json` (with a `files` block) is missing locally, `.wikitool-kb.json` is missing, a migration is already outstanding against the *installed* machinery, or the working tree is dirty (not being a git repository at all is a WARN, not a refusal). Refuses after reading the source when: it carries no `VERSION`/`.wikitool-release.json`/`files` block, its version is older than or equal to the installed one (equal is a no-op success), or it is a pre-release (`-beta.N`) without `--pre`. Reports, but does not block on, a crossed compatibility boundary. Never touches git - no commit, no push (invariant 5). See Gitea #7 and `INSTALL.md` § "Eine Instanz aktualisieren" |
 | `version show [--json]` | Print this instance's stack version and where it came from (development tree, or a distribution with its export date and origin). Bare `wikitool version` is an alias for this. Read-only, offline, and **exempt from the Iteration Budget Gate** |
 | `version check [--url U] [--timeout S] [--json]` | Ask the origin's release feed whether a newer stack exists, and whether the step crosses a compatibility boundary (`state: current\|update\|migration\|ahead`). **The only command in `wikitool` that makes a network call** - never reached implicitly from another command, needs no key, times out, and reports an unreachable feed as an error rather than as "up to date". The feed is `$WIKITOOL_UPDATE_URL`, else the release stamp's, else the built-in origin; `$WIKITOOL_UPDATE_TOKEN` is only needed if that feed is not readable anonymously. Read-only and exempt from the budget gate |
 | `version notes [--version X.Y.Z]` | Print one version's `CHANGES.md` entry, for use as release notes (default: this tree's `VERSION`). Read-only and exempt from the budget gate |
@@ -82,6 +83,8 @@ tools/wikitool <command> --help
 | `migrate verify --from <rev> [--path P ...] [--expect-body-change] [--json] [--fail-on-error]` | Compare `kb/` against a git revision on the invariants a content migration must not change: wikilink and citation **counts** (not sets), footnote definitions, H1, structural frontmatter, and the **count of generated-region marker pairs** - a page that went from one links region to two has the same set of region names and a different count, and a lost marker turns a generated region into prose the next write appends a second one beside. Reports added/removed pages without failing on them. `--expect-body-change` additionally flags a page whose body did not change at all. Not migration-specific - worth running after any bulk rewrite, and the one question `lint` cannot answer, since it reads a single revision and so cannot see that something went missing. Read-only and exempt from the budget gate |
 | `migrate done <version> [--pages N] [--dry-run]` | Record one migration as applied, advancing `kb_version` in `.wikitool-kb.json` to its target. **Refuses any version that is not the next link in the chain** - skipping one leaves the corpus in a shape no version describes, and an interrupted multi-step upgrade has to be resumable rather than guessable. An `offered` migration is recorded in the applied ledger *without* moving `kb_version` and with no ordering rule applied: it is not a link in the chain, so there is nothing to skip, and requiring the chain first would make an unrelated file upgrade wait on it. Re-recording one already in the ledger is a no-op, not an error |
 | `migrate baseline <version> [--force]` | Declare `kb_version` once, for an instance predating `.wikitool-kb.json`. Refuses to overwrite an existing declaration without `--force`: advancing after a migration is `done`, which checks the chain, and this command must not become the quiet way around it |
+| `upstream merge [--remote upstream] [--branch main] [--no-fetch]` | Take a stack update into a private instance's branch, machinery only - the code procedure behind `instructions/private-instance.md` § "Taking a stack update". Refuses on a dirty working tree, a merge already in progress, or a remote that does not resolve; WARNs (does not block) when `.wikitool-remotes.json` is absent, pointing at the setup step that arms it. Fetches `<remote>/<branch>` (unless `--no-fetch`) and reports "already up to date" if nothing new exists. Otherwise opens `git merge --no-commit --no-ff <remote>/<branch>` - and stops, untouched, if git refused to open a merge at all (unrelated histories), since without a `MERGE_HEAD` every stack path would read as "the upstream deleted it". Then forces every content stage (`kb/`, `raw/`, `work/`, `reports/`) back to the local side by removing **only the paths tracked in either tree** and checking `HEAD`'s back out - never the stage directory wholesale, because `reports/` is gitignored apart from its contract and holds local, non-recomputable data (telemetry traces `eval score` reads, saved eval and lint reports) that no merge has business deleting. Then restores from the upstream side exactly the paths `chemenu.ownership.is_stack_owned` recognises as machinery (`<stage>/CONTRACT.md`, and anything ending `.template` under a content stage) - including a deletion, if the upstream removed one. A real conflict left in `tools/`, `types/` or `instructions/` after that leaves the merge open, uncommitted, and exits 1 rather than guessing. Commits with `git commit --no-edit`, then re-checks the resulting range with the same logic as `upstream verify`; a finding there is a loud, uncommitted-nothing-rolled-back error, because the merge commit already exists and needs a human's eyes, not an automatic repair. Never pushes. Not idempotent - see the tool error contract below |
+| `upstream verify --since <rev> [--until HEAD]` | Compare two revisions: did anything under a content stage (`kb/`, `raw/`, `work/`, `reports/`) change except through a stack-owned path? Shares its check with `upstream merge`'s own postcheck, so a hand-resolved merge conflict, or a future `dist upgrade` (#7), can be verified the same way. Exit 1 with the offending paths if anything leaked; otherwise reports which stack-owned paths legitimately moved. Read-only and exempt from the Iteration Budget Gate, like `migrate verify` |
 | `doctor [--json]` | Check that this instance is correctly configured: dependencies (Python, ripgrep), author resolution, stack version, git identity/branch/remote, published skills, kb/raw/reports/work/instructions structure, personalization (`USER.md`/`SOUL.md` present **and** filled - a file still carrying the template's sentinel is a `FAIL`, since a renamed template is not a filled one), the KB conventions (`kb/CONVENTIONS.md` present, unsentinelled, and naming all three tool-owned section headings - a `FAIL` on any of the three, because `xref`/`cite` write out of it), the environment note (`ENVIRONMENT.md` - optional, so absent is `OK`; a still-templated one is a `WARN`), generated files, and `WIKITOOL_SESSION_ID`. Read-only, exit 1 only on a `FAIL` (a missing remote, session id, or `VERSION` is a `WARN`, not a fault). Exempt from the Iteration Budget Gate |
 
 ## Design notes
@@ -190,6 +193,7 @@ is atomic, and whether a retry is safe.
 | `instructions sync` / `verify` / `list` | Nothing found under `instructions/`, a malformed instruction or `SKILL.md`, a published copy that drifted from its source, an instruction nothing references (or, for `manual: true`, one that IS linked from AGENTS.md or a skill and so risks running implicitly), something under `instructions/dev/` referenced from outside it and outside a dist:strip block, or (sync) a target directory that is not a published skill and `--force` was not passed | `sync` rewrites one directory per target (idempotent); `verify`/`list` are read-only | Fix the flagged file, then re-run. For drift, re-run `sync`: the source under `instructions/` always wins, and a published copy is never edited directly |
 | `docs verify` | A command, contract, or type-form mismatch was found | Read-only | Fix the documentation it names, then re-run |
 | `dist export` | Target exists and is not empty, is not a directory, or the tree has no readable `VERSION` | Yes - nothing is written until every file is planned | Point `<target>` at an empty (or new) directory and retry. Never merge into a non-empty one by hand |
+| `dist upgrade` | Missing local `VERSION`/`.wikitool-release.json`(`files`)/`.wikitool-kb.json`, a migration already outstanding against the installed machinery, a dirty working tree, a source with no `VERSION`/stamp/`files` block, a source version that is older than, equal to, or (without `--pre`) a pre-release relative to the installed one, or one or more locally changed files without `--keep-local` | **Yes for the refusal cases above - nothing is written.** Once writing starts it is a plain sequential file copy with no partial-state cleanup: an interruption mid-copy (killed process, disk full) can leave the tree part-old, part-new | For every refusal above: fix the named precondition and retry - none of them are transient. For locally changed files: reconcile them by hand and retry, or re-run with `--keep-local` to proceed and leave them untouched (repeatable - it reports the same files again on every subsequent run until they stop diverging). An interrupted write is not resumed automatically; compare the tree against the printed classification and finish or revert by hand |
 | `version show` / `version notes` | `VERSION` is missing or unparseable; for `notes`, no `CHANGES.md` entry names the version asked for | Read-only | Fix `VERSION`, or write the changelog entry (`version bump` writes its heading). Safe to retry |
 | `version check` | The feed could not be reached, answered non-JSON, or carried no `tag_name`. **Never** answers "up to date" for a question it could not ask | Read-only, no local writes | A network failure is transient - retry once, then report it. HTTP 401/403 names `$WIKITOOL_UPDATE_TOKEN`; 404 means no release exists yet or the URL points at the wrong repo |
 | `version bump` | More or fewer than one of `--major/--minor/--patch`, an empty `--title`, a missing `VERSION`/`CHANGES.md`, `VERSION` and the changelog's newest entry naming different versions, an escalation to a boundary crossing without `--breaking` or with neither a migration document nor `--no-migration`, or `--breaking`/`--no-migration` on a bump that crosses nothing | No - `VERSION` then `CHANGES.md` | **Not idempotent**: a second run escalates or continues the candidate again. If the outcome is uncertain, read `VERSION` and the top of `CHANGES.md` before retrying |
@@ -199,6 +203,8 @@ is atomic, and whether a retry is safe.
 | `migrate verify` | Only with `--fail-on-error`: an invariant changed. Also exits 1 if `--from` is not a revision in this repository | Read-only | Exit 1 from `--fail-on-error` means "act on the findings", not "the tool is broken". A finding is never fixed by re-running - it names a page and what changed on it |
 | `migrate done` | Unknown version, no `.wikitool-kb.json`, nothing outstanding, or a *required* version that is not the next link in the chain | Yes - single file write | **Not idempotent** for a required migration: it advances the chain. For "not the next link", run `migrate status` and apply them in the order it prints - never force the order. Recording an `offered` migration *is* idempotent and safe to repeat |
 | `migrate baseline` | Unparseable version, or a declaration already exists and `--force` was not passed | Yes - single file write | Safe to re-run with the same version. If a declaration exists, it is almost always `migrate done` that was wanted |
+| `upstream merge` | Dirty working tree, a merge already in progress, the remote does not resolve, git refused to open the merge at all (unrelated histories), or a real conflict remains in `tools/`/`types/`/`instructions/` after the content stages and stack-owned paths were restored | **No** - can leave an open, uncommitted merge behind on refusal after fetching | **Not idempotent, and not safe to retry unchanged.** For a dirty tree or an in-progress merge: fix the named precondition and retry once. For a real conflict: **do not retry, do not force** - resolve the named paths by hand (take the upstream side, or re-file the local change as an issue against the public repo per `instructions/private-instance.md`) and either `git commit --no-edit` yourself or `git merge --abort`. If the postcheck after commit finds a leak, the merge commit already exists and is **not** rolled back automatically - inspect it by hand; this is a bug report, not a retry |
+| `upstream verify` | A leak was found (content changed under a content stage through a path that is not stack-owned), or `--since`/`--until` is not a revision in this repository | Read-only | A finding is not fixed by re-running - it names the paths that leaked. Fix the revision argument and retry for the second case |
 | `doctor` | At least one check reported `FAIL` (a `WARN`, e.g. no remote or no `WIKITOOL_SESSION_ID`, does not exit 1) | Read-only | Each finding names its own fix command; re-run after applying it |
 | `budget status` / `budget reset` | `reset` without `--yes`; `status` never fails | Read/rewrite of one JSON file | `status` is safe to retry. For `reset`: get the user's approval, then re-run with `--yes` |
 | `eval sessions` | Never fails; an empty list is a valid answer | Read-only | - |

tools/README.md

@@ -43,6 +43,7 @@ tools/
     links.py               labelled edges in `related:` - the graph's semantics as data, not prose
     kb_collections.py      collection discovery (a directory with COLLECTION.md), and what one declares about itself
     conventions.py         kb/CONVENTIONS.md: what this instance decided about authoring, as opposed to what the stack enforces
+    ownership.py           the stack-vs-instance boundary under a content stage - one predicate, read by `dist_cmd.py` and `commands/upstream_cmd.py` so the two cannot answer it differently
     type_resolver.py       type-spec loading and schema resolution
     lint_core.py           the lint checks and the report, with no CLI attached
     types_core.py          type-spec listing/description, with no CLI attached

tools/chemenu/cli.py

@@ -31,6 +31,7 @@ try:
         search as search_module,
         touch as touch_module,
         types_cmd,
+        upstream_cmd,
         version_cmd,
         work_cmd,
         xref,
@@ -69,6 +70,7 @@ app.add_typer(eval_cmd.app, name="eval")
 app.add_typer(dist_cmd.app, name="dist")
 app.add_typer(version_cmd.app, name="version")
 app.add_typer(migrate_cmd.app, name="migrate")
+app.add_typer(upstream_cmd.app, name="upstream")
 app.command("new")(new_page.new_page_command)
 app.command("touch")(touch_module.touch_command)
 app.command("rename")(page_ops.rename_command)

tools/chemenu/commands/dist_cmd.py

@@ -33,14 +33,20 @@ import hashlib
 import json
 import os
 import re
+import shutil
 import stat
+import subprocess
+import tarfile
+import tempfile
+from contextlib import contextmanager
+from dataclasses import dataclass
 from pathlib import Path
 from typing import Callable, NamedTuple, Optional, Union
 
 import typer
 
-from chemenu import config, conventions, kb_collections, kb_state, version as version_mod
+from chemenu import config, conventions, kb_collections, kb_state, ownership, version as version_mod
-from chemenu.commands._util import fail, rel_path, success, today_iso
+from chemenu.commands._util import console, fail, rel_path, success, today_iso
 
 app = typer.Typer(help="Build a distributable copy of the wiki machinery.")
 
@@ -132,8 +138,15 @@ INSTRUCTIONS_EXCLUDE_DIRS = {"dev"}
 RAW_SUBDIRS = ("articles", "documents", "notes", "assets")
 
 # Stage contracts that are not collections and carry no pages: copied as a
-# single file each, nothing else from their directory.
+# single file each, nothing else from their directory. `kb/` is excluded here
-CONTRACT_ONLY_STAGES = ("raw/CONTRACT.md", "reports/CONTRACT.md", "work/CONTRACT.md")
+# - it is a content stage too, but it has collections underneath it, so its
+# contract is handled by `build_plan` alongside them rather than as a bare
+# stage copy. Derived from `ownership.CONTENT_STAGES` rather than listed
+# again, so the set this loop copies and the set `upstream merge` restores
+# cannot name a different stage without one of them failing its own test.
+CONTRACT_ONLY_STAGES = tuple(
+    f"{stage}/CONTRACT.md" for stage in ownership.CONTENT_STAGES if stage != "kb"
+)
 
 # Single tracked files copied out of an otherwise-untouched, partially-ignored
 # directory. `.claude/` holds the harness's own session-tracing config
@@ -439,19 +452,20 @@ def build_plan(origin: Optional[Origin] = None) -> dict[str, PlannedFile]:
 # appears in INSTALL.md and version.py, so such a scan would either whitelist
 # the very string it is looking for or cry wolf on every export.
 #
-# `COLLECTION.md` and `CONVENTIONS.md` are deliberately *not* on the allowed
+# `COLLECTION.md` and `CONVENTIONS.md` are deliberately *not* allowed through
-# list any more. Both bind, and both are the instance's to write, so they cross
+# any more. Both bind, and both are the instance's to write, so they cross the
-# the boundary as `.template` and are adopted by a rename - a plan carrying the
+# boundary as `.template` and are adopted by a rename - a plan carrying the
 # filled name would hand a new instance this one's authoring conventions as
 # though they were the stack's.
+#
+# What counts as machinery under kb/ or raw/ is no longer a second list here:
+# it is `ownership.is_stack_owned`, the same predicate `upstream merge` and
+# `upstream verify` restore/check against. Only the export-only stubs
+# (`ownership.EXPORT_STUB_NAMES`) are allowed here without also being
+# stack-owned - a merge keeps the *local* copy of those, while export writes a
+# fresh one regardless of either side, so the two callers genuinely disagree
+# about them and each keeps its own allowance for that one case.
 _CONTENT_PREFIXES = ("kb/", "raw/")
-_CONTENT_ALLOWED_NAMES = (
-    "CONTRACT.md",
-    f"{kb_collections.CONTRACT_NAME}.template",
-    conventions.CONVENTIONS_TEMPLATE,
-    "log.md",
-    ".gitkeep",
-)
 _INSTANCE_OWNED_KB_FILES = (kb_collections.CONTRACT_NAME, conventions.CONVENTIONS_FILENAME)
 
 
@@ -473,7 +487,11 @@ def find_leaks(plan: dict[str, PlannedFile]) -> list[str]:
             leaks.append(f"{relative} (this instance's page type-spec; ship the .template)")
         elif relative.startswith("instructions/dev/"):
             leaks.append(f"{relative} (stack-development only)")
-        elif relative.startswith(_CONTENT_PREFIXES) and name not in _CONTENT_ALLOWED_NAMES:
+        elif (
+            relative.startswith(_CONTENT_PREFIXES)
+            and not ownership.is_stack_owned(relative)
+            and not ownership.is_export_stub(name)
+        ):
             leaks.append(f"{relative} (wiki content, not machinery)")
     return leaks
 
@@ -569,3 +587,405 @@ def run_export(target: Path, dry_run: bool = False, origin: Optional[Origin] = N
 
     _write_plan(target, plan)
     success(f"Exported {len(plan)} file(s) to {rel_path(target)}.")
+
+
+# --- dist upgrade ------------------------------------------------------------
+#
+# Apply a release `dist export` produced, rather than merely detecting one
+# (`version check`). Gitea #7 has the full design; the short version: the
+# write set is exactly the *new* stamp's `files` block, minus the paths an
+# export seeds once and the instance owns from then on
+# (`ownership.is_export_stub`, `ownership.is_upgrade_preserved`), plus the
+# stamp itself. Every candidate path is classified against the *old* stamp's
+# recorded digest - unchanged, locally modified, or locally deleted - and a
+# modified/deleted file is never silently overwritten. This never calls a
+# release feed; the caller supplies an already-downloaded tree or archive.
+
+
+@dataclass(frozen=True)
+class FileClassification:
+    """The four-way split of every path `dist upgrade` would touch, plus the
+    fifth direction (`removed`) that has no write set of its own."""
+
+    unchanged: list[str]
+    modified: list[str]
+    deleted: list[str]
+    new: list[str]
+    removed: list[str]
+
+    @property
+    def blocked(self) -> list[str]:
+        """Locally changed paths - modified or deleted - which are never
+        silently overwritten."""
+        return sorted(self.modified + self.deleted)
+
+
+def _write_candidates(new_files: dict) -> set[str]:
+    """Every path `dist upgrade` may write, from the new stamp's `files`
+    block: everything except the paths an export re-seeds from a blank
+    template every time (`ownership.is_export_stub`) and the paths an export
+    seeds once and the instance owns afterward (`ownership.is_upgrade_preserved`).
+    The release stamp itself is added separately - it is never a member of its
+    own `files` block, see `build_stamp`."""
+    return {
+        relative
+        for relative in new_files
+        if not ownership.is_export_stub(Path(relative).name)
+        and not ownership.is_upgrade_preserved(relative)
+    }
+
+
+def _classify_files(old_files: dict, new_files: dict) -> FileClassification:
+    candidates = _write_candidates(new_files)
+    recorded_for_candidates = {r: d for r, d in old_files.items() if r in candidates}
+    statuses = kb_state.compare_against_stamp(recorded_for_candidates)
+
+    unchanged: list[str] = []
+    modified: list[str] = []
+    deleted: list[str] = []
+    new: list[str] = []
+    for relative in sorted(candidates):
+        if relative not in old_files:
+            new.append(relative)
+            continue
+        status = statuses[relative]
+        if status == kb_state.UNCHANGED:
+            unchanged.append(relative)
+        elif status == kb_state.MODIFIED:
+            modified.append(relative)
+        else:
+            deleted.append(relative)
+
+    removed = sorted(set(old_files) - set(new_files))
+    return FileClassification(unchanged, modified, deleted, new, removed)
+
+
+def _verify_sha256_sidecar(archive: Path) -> None:
+    """WARN, never fail, on a missing sidecar - only a corrupted one that
+    *is* present is a reason to stop, per Gitea #7's design table."""
+    sidecar = archive.with_name(archive.name + ".sha256")
+    if not sidecar.is_file():
+        console.print(
+            f"[yellow]WARN[/yellow] No {sidecar.name} beside {archive.name} - the archive's "
+            "integrity is not being checked before it is extracted."
+        )
+        return
+    expected = sidecar.read_text(encoding="utf-8").strip().split()[0:1]
+    actual = hashlib.sha256(archive.read_bytes()).hexdigest()
+    if not expected or expected[0].lower() != actual.lower():
+        fail(
+            f"{archive.name} does not match {sidecar.name}: expected "
+            f"{expected[0] if expected else '(unreadable)'}, got {actual}. Re-download the "
+            "release archive rather than trusting one that failed its own checksum."
+        )
+
+
+def _extract_single_top_level_dir(archive: Path, dest: Path) -> Path:
+    """Extract `archive` into `dest` and return the one top-level directory it
+    contained - the shape `.gitea/workflows/release.yml` packs (see its
+    `Build the distribution tarball` step). Refuses anything else rather than
+    guessing which part is the machinery."""
+    with tarfile.open(archive) as tf:
+        names = [n for n in tf.getnames() if n not in ("", ".")]
+        top_levels = {n.split("/", 1)[0] for n in names}
+        if len(top_levels) != 1:
+            fail(
+                f"{archive.name} does not have exactly one top-level directory (found "
+                f"{len(top_levels)}: {', '.join(sorted(top_levels)) or '(empty archive)'}) - this "
+                "is not the shape a release tarball has, and `dist upgrade` refuses to guess "
+                "which part is the machinery."
+            )
+            return dest  # unreachable: fail() raises typer.Exit
+        try:
+            tf.extractall(dest, filter="data")  # noqa: S202 - trusted local archive, path-checked below
+        except TypeError:
+            # Python < 3.12 has no `filter=` argument. Same guard by hand:
+            # refuse any member whose extracted path would land outside dest.
+            resolved_dest = dest.resolve()
+            for member in tf.getmembers():
+                if not (resolved_dest / member.name).resolve().is_relative_to(resolved_dest):
+                    fail(
+                        f"{archive.name} contains a path that escapes the extraction directory: "
+                        f"{member.name}"
+                    )
+                    return dest  # unreachable
+            tf.extractall(dest)  # noqa: S202 - every member path-checked above
+    return dest / next(iter(top_levels))
+
+
+@contextmanager
+def _resolved_source(source: Path):
+    """Yield the directory holding a distribution export: `source` itself if
+    it already is one, or the single top-level directory of a `.tar.gz`
+    extracted into a scratch directory that is cleaned up afterward."""
+    if source.is_dir():
+        yield source
+        return
+    if not source.is_file():
+        fail(f"{source} does not exist.")
+        return
+    _verify_sha256_sidecar(source)
+    with tempfile.TemporaryDirectory(prefix="wikitool-upgrade-") as tmp:
+        yield _extract_single_top_level_dir(source, Path(tmp))
+
+
+def _git_working_tree_status() -> Optional[str]:
+    """`git status --porcelain` for `config.ROOT`, or None if it is not a git
+    repository at all - which is a valid, if unprotected, state for a tarball
+    instance, not a reason to refuse."""
+    result = subprocess.run(
+        ["git", "-C", str(config.ROOT), "status", "--porcelain"],
+        capture_output=True,
+        text=True,
+    )
+    return result.stdout if result.returncode == 0 else None
+
+
+def _report_plan(
+    classification: FileClassification,
+    migration_chain: list["kb_state.Migration"],
+    boundary_crossing: bool,
+    local_version: "version_mod.Version",
+    new_version: "version_mod.Version",
+) -> None:
+    console.print(f"{local_version} -> {new_version}")
+    if boundary_crossing:
+        console.print(
+            f"[bold yellow]Crosses a compatibility boundary[/bold yellow] "
+            f"({local_version.compat_key} -> {new_version.compat_key}) - this is not a drop-in "
+            "swap; check the release notes before proceeding."
+        )
+    console.print(
+        f"{len(classification.unchanged)} unchanged, {len(classification.new)} new, "
+        f"{len(classification.blocked)} locally changed, {len(classification.removed)} removed "
+        "from the release."
+    )
+    if classification.modified:
+        console.print(f"[bold]Locally modified ({len(classification.modified)}):[/bold]")
+        for relative in classification.modified:
+            console.print(f"  - {relative}")
+    if classification.deleted:
+        console.print(f"[bold]Locally deleted ({len(classification.deleted)}):[/bold]")
+        for relative in classification.deleted:
+            console.print(f"  - {relative}")
+    if classification.removed:
+        console.print("[dim]No longer part of the release, not written or removed by default:[/dim]")
+        for relative in classification.removed:
+            console.print(f"  [dim]- {relative}[/dim]")
+    if migration_chain:
+        console.print(
+            f"[cyan]{len(migration_chain)} migration(s) will be outstanding after this "
+            "upgrade, in this order:[/cyan]"
+        )
+        for position, migration in enumerate(migration_chain, start=1):
+            console.print(f"  {position}. {migration.target}  {migration.name}  ({migration.kind})")
+        console.print("Report only - `dist upgrade` never runs a migration. See `wikitool migrate status`.")
+
+
+@app.command("upgrade")
+def upgrade_command(
+    source: Path = typer.Argument(
+        ..., help="An extracted distribution directory, or a release .tar.gz archive"
+    ),
+    dry_run: bool = typer.Option(
+        False, "--dry-run", help="Classify and report, without writing anything"
+    ),
+    keep_local: bool = typer.Option(
+        False, "--keep-local",
+        help="Proceed even with locally changed files - leave each one untouched rather than aborting",
+    ),
+    prune: bool = typer.Option(
+        False, "--prune",
+        help="Also delete files the new release no longer ships, if they are unchanged since install",
+    ),
+    allow_pre: bool = typer.Option(
+        False, "--pre", help="Allow a pre-release (-beta.N) source tree - release.yml never publishes one",
+    ),
+):
+    """Apply a stack update `dist export` produced - the write half of
+    `version check`. Never downloads anything: `source` is an already-fetched
+    export directory or `.tar.gz` archive. Writes exactly the new release
+    stamp's `files` block, minus what an export re-seeds every time
+    (`kb/log.md`, `raw/*/.gitkeep`) or seeds once and the instance owns from
+    then on (`.wikitool-kb.json`, `CHANGES.md`), classifying every candidate
+    against the *old* stamp's recorded digest: unchanged files are
+    overwritten silently, new files are created, and a locally modified or
+    deleted file is never silently overwritten - `dist upgrade` aborts unless
+    `--keep-local` says to leave it alone. Reports the migration chain the new
+    machinery would owe without running any of it (there is no `migrate run`).
+    Refuses on a missing local release stamp, a downgrade, a pre-release
+    source without `--pre`, or a dirty working tree. Never touches git.
+    See Gitea #7 and `INSTALL.md` § "Eine Instanz aktualisieren"."""
+    run_upgrade(
+        source, dry_run=dry_run, keep_local=keep_local, prune=prune, allow_pre=allow_pre
+    )
+
+
+def run_upgrade(
+    source: Path,
+    dry_run: bool = False,
+    keep_local: bool = False,
+    prune: bool = False,
+    allow_pre: bool = False,
+) -> None:
+    """The upgrade itself, free of Typer's option objects - see `run_export`
+    for why this split exists."""
+    try:
+        local_version = version_mod.read_version()
+    except version_mod.VersionError as exc:
+        fail(f"{exc} - this tree has no stack version to upgrade from.")
+        return
+
+    old_stamp = version_mod.read_stamp()
+    if not old_stamp or not isinstance(old_stamp.get("files"), dict):
+        fail(
+            f"No local {version_mod.RELEASE_STAMP_FILENAME} (or it carries no `files` block). "
+            "Without it, `dist upgrade` cannot tell a file this instance edited from one it "
+            "merely received, and it refuses to guess. A checkout with shared git history takes "
+            "stack updates via `wikitool upstream merge` instead - it has the same information "
+            "as a merge base. A tarball instance that has lost its stamp has no repair path "
+            "today; see Gitea #7 \"Bewusst offen gelassen\"."
+        )
+        return
+    old_files = old_stamp["files"]
+
+    try:
+        kb_version = kb_state.read_kb_version()
+    except version_mod.VersionError as exc:
+        fail(str(exc))
+        return
+    if kb_version is None:
+        fail(
+            f"{kb_state.KB_STATE_FILENAME} is missing - this instance has never declared what "
+            "shape its content is in. Run `wikitool migrate baseline <version>` before upgrading."
+        )
+        return
+
+    outstanding = kb_state.chain(kb_state.load_migrations(), kb_version, local_version.base)
+    if outstanding:
+        fail(
+            f"{len(outstanding)} migration(s) are already outstanding against the installed "
+            f"machinery ({kb_version} -> {local_version}) - `wikitool migrate status` names them. "
+            "Finish them before upgrading further: a machinery swap on top of an unfinished "
+            "migration leaves the corpus in a shape no version describes."
+        )
+        return
+
+    tree_status = _git_working_tree_status()
+    if tree_status is None:
+        console.print(
+            "[yellow]WARN[/yellow] Not a git repository (or git is unavailable) - proceeding "
+            "without the dirty-tree check a repository would get."
+        )
+    elif tree_status.strip():
+        fail(
+            "Working tree is not clean (`git status --porcelain` printed something). "
+            "`dist upgrade` refuses to start on a dirty tree so a refusal never has to guess "
+            "which changes were already there. Commit or stash first."
+        )
+        return
+
+    with _resolved_source(source) as new_root:
+        version_path = new_root / version_mod.VERSION_FILENAME
+        if not version_path.is_file():
+            fail(f"{rel_path(new_root)} has no VERSION - not a distribution export.")
+            return
+        try:
+            new_version = version_mod.Version.parse(version_path.read_text(encoding="utf-8"))
+        except version_mod.VersionError as exc:
+            fail(str(exc))
+            return
+
+        if new_version.is_prerelease and not allow_pre:
+            fail(
+                f"{new_version} is a running candidate (-beta.N). `.gitea/workflows/release.yml` "
+                "never publishes one, so a candidate tree can only come from a dev checkout by "
+                "hand - pass --pre if that is deliberate."
+            )
+            return
+        if new_version < local_version:
+            fail(f"{new_version} is older than the installed {local_version} - refusing a downgrade.")
+            return
+        if new_version == local_version:
+            success(f"Already at {local_version}. Nothing to do.")
+            return
+
+        stamp_path = new_root / version_mod.RELEASE_STAMP_FILENAME
+        if not stamp_path.is_file():
+            fail(f"{rel_path(new_root)} has no {version_mod.RELEASE_STAMP_FILENAME} - not a distribution export.")
+            return
+        try:
+            new_stamp = json.loads(stamp_path.read_text(encoding="utf-8"))
+        except (json.JSONDecodeError, OSError) as exc:
+            fail(f"{version_mod.RELEASE_STAMP_FILENAME} in the source is not readable JSON: {exc}")
+            return
+        new_files = new_stamp.get("files") if isinstance(new_stamp, dict) else None
+        if not isinstance(new_files, dict):
+            fail(f"{version_mod.RELEASE_STAMP_FILENAME} in the source carries no `files` block.")
+            return
+
+        classification = _classify_files(old_files, new_files)
+        migration_chain = kb_state.chain(
+            kb_state.load_migrations(new_root / "instructions" / kb_state.MIGRATIONS_SUBDIR),
+            kb_version,
+            new_version.base,
+        )
+        boundary_crossing = local_version.compat_key != new_version.compat_key
+
+        _report_plan(classification, migration_chain, boundary_crossing, local_version, new_version)
+
+        # Dry-run's whole purpose is to preview this classification - including
+        # the blocked list - without raising, so it must be checked before the
+        # abort below rather than after: a blocked file must never turn
+        # `--dry-run` into a non-zero exit, or the flag stops being safe to run
+        # freely.
+        if dry_run:
+            success(f"Dry run: would upgrade {local_version} -> {new_version}. Nothing written.")
+            return
+
+        if classification.blocked and not keep_local:
+            fail(
+                f"{len(classification.blocked)} locally changed file(s) (listed above) would be "
+                "silently overwritten. Pass --keep-local to upgrade anyway and leave every one of "
+                "them untouched, or reconcile them by hand first. Nothing was written."
+            )
+            return
+
+        to_write = sorted(classification.unchanged + classification.new)
+        for relative in to_write:
+            src = new_root / relative
+            dst = config.ROOT / relative
+            dst.parent.mkdir(parents=True, exist_ok=True)
+            shutil.copy2(src, dst)
+        shutil.copy2(stamp_path, config.ROOT / version_mod.RELEASE_STAMP_FILENAME)
+
+        pruned: list[str] = []
+        if prune:
+            for relative in classification.removed:
+                digest = old_files.get(relative)
+                if digest is None:
+                    continue
+                status = kb_state.compare_against_stamp({relative: digest}).get(relative)
+                if status != kb_state.UNCHANGED:
+                    continue
+                target = config.ROOT / relative
+                if target.is_file():
+                    target.unlink()
+                    pruned.append(relative)
+
+    skipped = classification.blocked if keep_local else []
+    summary = (
+        f"Upgraded {local_version} -> {new_version}: {len(to_write)} file(s) written"
+        + (f", {len(skipped)} left untouched (--keep-local)" if skipped else "")
+        + (f", {len(pruned)} pruned" if pruned else "")
+        + "."
+    )
+    if migration_chain:
+        summary += (
+            f" {len(migration_chain)} migration(s) now outstanding - run `wikitool migrate status`."
+        )
+    summary += (
+        " Nothing was committed. Now run, in order: `wikitool instructions sync`, `doctor`, "
+        "`docs verify`, `instructions verify`, `lint` - then restart the agent session."
+    )
+    success(summary)

tools/chemenu/commands/run_budget.py

@@ -101,6 +101,13 @@ SKIP_COMMAND_PATHS = {
     ("migrate", "list"),
     ("migrate", "status"),
     ("migrate", "verify"),
+    # `upstream verify` only reads two git revisions and reports what changed -
+    # the same argument as `migrate verify`: a check that costs budget is one
+    # an agent starts skipping. `upstream merge` stays counted: it mutates the
+    # branch and can leave an open merge behind on refusal, so it belongs on
+    # the non-idempotent list (AGENTS.md's tool error contract) rather than
+    # the exempt one.
+    ("upstream", "verify"),
 }
 
 # Commands exempt regardless of their first argument, because that argument is

tools/chemenu/commands/upstream_cmd.py

@@ -0,0 +1,387 @@
+"""`wikitool upstream` - take a stack update from a public upstream into a
+private instance's `main` without letting the upstream's own content (a demo
+corpus, a workshop run) ride along.
+
+`git merge upstream/main` on its own treats a moved corpus dangerously
+asymmetrically: a page the instance deleted and the upstream edited reports as
+a conflict, a page the upstream *added* stages silently, and a page both sides
+deleted is the only harmless case. `instructions/private-instance.md`'s prose
+procedure closes that, by holding the merge open, forcing the content stages
+(`ownership.CONTENT_STAGES`) back to the local side, and then restoring only
+the paths `ownership.is_stack_owned` recognises as machinery. `upstream merge`
+is that procedure in code, so the path set it acts on cannot drift from the
+one `dist_cmd.py` ships - both read `chemenu.ownership` - and so a conflict in
+the machinery layers, or a machinery file the upstream deleted, gets an
+explained stop instead of a silently wrong commit.
+
+`upstream verify` is the other half: given two revisions, did anything change
+under a content stage except through a stack-owned path? It shares
+`_content_leaks` with the postcheck `upstream merge` runs on itself, so a
+hand-resolved merge or a future `dist upgrade` (Gitea #7) can be checked the
+same way.
+"""
+from __future__ import annotations
+
+from pathlib import Path
+from typing import Optional
+
+import typer
+
+from chemenu import config, ownership
+from chemenu.commands import git_publish
+from chemenu.commands._util import console, fail, success
+
+app = typer.Typer(help="Take a stack update from a public upstream, machinery only.")
+
+
+def _run(args: list[str]):
+    import subprocess
+
+    return subprocess.run(args, cwd=config.ROOT, capture_output=True, text=True)
+
+
+def _rev_parse(rev: str) -> Optional[str]:
+    result = _run(["git", "rev-parse", "--verify", "-q", rev])
+    return result.stdout.strip() if result.returncode == 0 else None
+
+
+def _git_dir() -> Optional[Path]:
+    result = _run(["git", "rev-parse", "--git-dir"])
+    if result.returncode != 0:
+        return None
+    path = Path(result.stdout.strip())
+    return path if path.is_absolute() else config.ROOT / path
+
+
+def _working_tree_dirty() -> bool:
+    result = _run(["git", "status", "--porcelain"])
+    return bool(result.stdout.strip())
+
+
+def _merge_in_progress() -> bool:
+    git_dir = _git_dir()
+    return git_dir is not None and (git_dir / "MERGE_HEAD").exists()
+
+
+def _remote_resolves(remote: str) -> bool:
+    return _run(["git", "remote", "get-url", remote]).returncode == 0
+
+
+def _is_ancestor(ancestor: str, of: str) -> bool:
+    return _run(["git", "merge-base", "--is-ancestor", ancestor, of]).returncode == 0
+
+
+def _tree_has_path(rev: str, path: str) -> bool:
+    return _run(["git", "rev-parse", "--verify", "-q", f"{rev}:{path}"]).returncode == 0
+
+
+def _tree_paths(rev: str) -> set[str]:
+    result = _run(["git", "ls-tree", "-r", "--name-only", "-z", rev])
+    if result.returncode != 0:
+        return set()
+    return {p for p in result.stdout.split("\0") if p}
+
+
+def _content_leaks(since: str, until: str) -> list[str]:
+    """Paths under a content stage that changed between `since` and `until`
+    through something other than a stack-owned path. Shared by `upstream
+    merge`'s own postcheck and `upstream verify`, so the two cannot disagree
+    about what a clean update looks like."""
+    result = _run(["git", "diff", "--name-only", "-z", since, until, "--", *ownership.CONTENT_STAGES])
+    if result.returncode != 0:
+        fail(
+            f"`git diff {since} {until}` failed - is {since} a revision in this repository?\n"
+            f"{result.stderr}"
+        )
+        return []
+    changed = [p for p in result.stdout.split("\0") if p]
+    return sorted(p for p in changed if not ownership.is_stack_owned(p))
+
+
+def _stack_paths_changed(since: str, until: str) -> list[str]:
+    """The subset of the same diff that *is* a stack-owned path - the paths
+    that legitimately moved, for the success message."""
+    result = _run(["git", "diff", "--name-only", "-z", since, until, "--", *ownership.CONTENT_STAGES])
+    changed = [p for p in result.stdout.split("\0") if p]
+    return sorted(p for p in changed if ownership.is_stack_owned(p))
+
+
+# --- upstream merge ---------------------------------------------------------
+
+
+def _prune_empty_dirs(stage: str) -> None:
+    """Remove directories left empty under `stage` after tracked files were
+    deleted. git tracks no directories, so an emptied one is invisible to
+    `git status` and would otherwise linger in the working tree as litter -
+    an empty `kb/<area>/` that only ever existed in the upstream's corpus.
+    Never touches a directory that still holds anything, ignored files
+    included."""
+    stage_dir = config.ROOT / stage
+    if not stage_dir.is_dir():
+        return
+    for path in sorted(stage_dir.rglob("*"), key=lambda p: len(p.parts), reverse=True):
+        if path.is_dir() and not any(path.iterdir()):
+            path.rmdir()
+
+
+def _restore_stage_to_local(stage: str, tracked_paths: set[str]) -> None:
+    """Force one content stage back to the local (HEAD) side, whatever the
+    merge did to it.
+
+    Deletes **only what git tracks on either side** - never the stage
+    directory wholesale. That distinction is the whole point of this function:
+    `reports/` is gitignored except its contract (see .gitignore), so a
+    content stage's working tree legitimately holds local data that is not in
+    any tree and not recomputable - the telemetry traces `eval score` reads,
+    saved eval reports, past lint reports. A blanket `rm -rf` of the stage
+    takes all of it out as collateral for a merge that was never about it.
+
+    Handles a stage that exists only in MERGE_HEAD too (the upstream
+    introduced it): what the merge wrote is removed, and there is simply
+    nothing to check out from HEAD afterwards.
+    """
+    prefix = f"{stage}/"
+    stage_paths = [p for p in tracked_paths if p.startswith(prefix)]
+    if not stage_paths:
+        return
+
+    _run(["git", "rm", "-rq", "--cached", "--ignore-unmatch", stage])
+    for relative in stage_paths:
+        target = config.ROOT / relative
+        if target.is_file() or target.is_symlink():
+            target.unlink()
+    _prune_empty_dirs(stage)
+    if _tree_has_path("HEAD", stage):
+        _run(["git", "checkout", "HEAD", "--", stage])
+
+
+def _remote_gate_warning() -> None:
+    if git_publish.read_allowed_push_urls() is not None:
+        return
+    console.print(
+        "[bold yellow]WARN[/bold yellow] No .wikitool-remotes.json in this checkout - the "
+        "Publish-Remote Gate is unarmed, so a future `publish` to the wrong remote would not "
+        "be caught. `upstream merge` never pushes and proceeds regardless, but a checkout that "
+        "takes stack updates from a public upstream should arm the gate before its next publish "
+        "- see instructions/private-instance.md step 4."
+    )
+
+
+def _precondition_failure(remote: str) -> Optional[str]:
+    if _working_tree_dirty():
+        return (
+            "Working tree is not clean (`git status --porcelain` printed something). "
+            "`upstream merge` refuses to start on a dirty tree so a refusal never has to "
+            "guess which changes were already there. Commit or stash first."
+        )
+    if _merge_in_progress():
+        return (
+            "A merge is already in progress (.git/MERGE_HEAD exists). Resolve or abort it "
+            "(`git merge --abort`) before running `upstream merge`."
+        )
+    if not _remote_resolves(remote):
+        return f"Remote '{remote}' does not resolve (`git remote get-url {remote}` failed)."
+    return None
+
+
+def _unresolved_conflict_message(unresolved: list[str], remote: str, branch: str) -> str:
+    listed = "\n".join(f"  - {p}" for p in unresolved)
+    return (
+        f"A real conflict remains in the machinery layers after restoring the content stages "
+        f"and the stack-owned paths from {remote}/{branch}:\n{listed}\n\n"
+        "The merge is left open, uncommitted - nothing was written to the branch. Per "
+        "instructions/private-instance.md's decision points: this means the checkout changed "
+        "the stack locally, which private instances do not do. Take the upstream side for "
+        "these paths (`git checkout --theirs -- <path>` then `git add`) and re-file the local "
+        "change as an issue against the public repo, or resolve deliberately and "
+        "`git commit --no-edit` yourself. `git merge --abort` gives up the merge entirely."
+    )
+
+
+def _postcheck_failure_message(leaks: list[str], before: str) -> str:
+    listed = "\n".join(f"  - {p}" for p in leaks)
+    return (
+        f"The merge commit exists (content stages are not what they were before this ran), "
+        f"but it changed content outside of a stack-owned path:\n{listed}\n\n"
+        f"This was NOT rolled back - the state belongs in front of you, not behind an automatic "
+        f"repair the command applies to itself. Compare against the pre-merge commit ({before}) "
+        "and decide by hand whether to revert the merge commit, cherry-pick around it, or fix "
+        "forward. This is a bug in `upstream merge` or in `ownership.is_stack_owned` if it "
+        "reproduces - please report it rather than working around it silently."
+    )
+
+
+def _merge_success_message(
+    changed: list[str], deleted: list[str], remote: str, branch: str
+) -> str:
+    """What the merge actually did, measured against the pre-merge commit
+    rather than against what was restored.
+
+    `changed` is the real diff - restoring every stack-owned path from
+    MERGE_HEAD touches each of them whether or not the upstream moved any, so
+    reporting the restore list would claim seven updates for a merge that
+    changed one file, and a reader who checks would find the report wrong.
+    """
+    deleted_set = set(deleted)
+    lines = [
+        f"Merged {remote}/{branch}. Content stages "
+        f"({', '.join(ownership.CONTENT_STAGES)}) are unchanged."
+    ]
+    if changed:
+        lines.append(f"Stack paths changed ({len(changed)}):")
+        lines += [
+            f"  - {p}" + (" (deleted, following the upstream)" if p in deleted_set else "")
+            for p in changed
+        ]
+    else:
+        lines.append("No stack-owned path changed.")
+    return "\n".join(lines)
+
+
+@app.command("merge")
+def merge_command(
+    remote: str = typer.Option("upstream", "--remote", help="Remote to merge from"),
+    branch: str = typer.Option("main", "--branch", help="Branch to merge"),
+    no_fetch: bool = typer.Option(
+        False, "--no-fetch", help="Skip `git fetch <remote>` - use whatever is already fetched"
+    ),
+):
+    """Merge `<remote>/<branch>` into the current branch, machinery only:
+    every path under a content stage (kb/, raw/, work/, reports/) is forced
+    back to the local side except a stack-owned path (`<stage>/CONTRACT.md`,
+    or anything ending `.template` under a content stage), which is taken
+    from the upstream - including a deletion, if the upstream removed one. A
+    real conflict elsewhere (tools/, types/, instructions/) leaves the merge
+    open and unresolved rather than guessing. Not idempotent: it can leave an
+    open merge behind on refusal. See instructions/private-instance.md."""
+    problem = _precondition_failure(remote)
+    if problem:
+        fail(problem)
+        return
+
+    _remote_gate_warning()
+
+    before = _rev_parse("HEAD")
+    if before is None:
+        fail("HEAD does not resolve - is this a git repository with at least one commit?")
+        return
+
+    if not no_fetch:
+        fetch_result = _run(["git", "fetch", remote, branch])
+        if fetch_result.returncode != 0:
+            fail(f"`git fetch {remote} {branch}` failed:\n{fetch_result.stderr}")
+            return
+
+    remote_ref = f"{remote}/{branch}"
+    if _rev_parse(remote_ref) is None:
+        fail(f"'{remote_ref}' does not resolve - fetch it first, or check --remote/--branch.")
+        return
+
+    if _is_ancestor(remote_ref, "HEAD"):
+        success(f"Already up to date with {remote_ref}.")
+        return
+
+    # The exit code is deliberately not the test - conflicts under the content
+    # stages are expected here and are exactly what the next steps undo. What
+    # *is* load-bearing is that a merge actually opened: without MERGE_HEAD,
+    # `_tree_paths("MERGE_HEAD")` is empty, and every stack-owned path in HEAD
+    # would then read as "the upstream deleted it" and be removed. A merge git
+    # refused to start (unrelated histories, an ignored file in the way) must
+    # therefore stop here, with the tree untouched.
+    merge_result = _run(["git", "merge", "--no-commit", "--no-ff", remote_ref])
+    if not _merge_in_progress():
+        fail(
+            f"`git merge --no-commit --no-ff {remote_ref}` did not open a merge, so there is "
+            f"nothing to scope - the working tree is unchanged:\n"
+            f"{merge_result.stdout}{merge_result.stderr}"
+        )
+        return
+
+    merge_head_paths = _tree_paths("MERGE_HEAD")
+    head_paths = _tree_paths("HEAD")
+    tracked_paths = merge_head_paths | head_paths
+
+    for stage in ownership.CONTENT_STAGES:
+        _restore_stage_to_local(stage, tracked_paths)
+
+    stack_paths = sorted(
+        p for p in (merge_head_paths | head_paths) if ownership.is_stack_owned(p)
+    )
+
+    # Only the deletions are recorded: what was *restored* is every stack-owned
+    # path in MERGE_HEAD, which is not the same question as what changed - the
+    # success message asks git for that instead.
+    deleted: list[str] = []
+    for relative in stack_paths:
+        if relative in merge_head_paths:
+            checkout = _run(["git", "checkout", "MERGE_HEAD", "--", relative])
+            if checkout.returncode != 0:
+                fail(
+                    f"`git checkout MERGE_HEAD -- {relative}` failed even though it is listed "
+                    f"in MERGE_HEAD's own tree:\n{checkout.stderr}\nThe merge is left open."
+                )
+                return
+        else:
+            _run(["git", "rm", "-q", "--cached", "--ignore-unmatch", relative])
+            target = config.ROOT / relative
+            if target.exists():
+                target.unlink()
+            deleted.append(relative)
+
+    unresolved = [p for p in _run(["git", "diff", "--name-only", "--diff-filter=U"]).stdout.splitlines() if p]
+    if unresolved:
+        fail(_unresolved_conflict_message(unresolved, remote, branch))
+        return
+
+    commit_result = _run(["git", "commit", "--no-edit"])
+    if commit_result.returncode != 0:
+        fail(f"`git commit --no-edit` failed:\n{commit_result.stderr}")
+        return
+
+    leaks = _content_leaks(before, "HEAD")
+    if leaks:
+        fail(_postcheck_failure_message(leaks, before))
+        return
+
+    success(
+        _merge_success_message(_stack_paths_changed(before, "HEAD"), deleted, remote, branch)
+    )
+
+
+# --- upstream verify ---------------------------------------------------------
+
+
+def _verify_failure_message(leaks: list[str], since: str, until: str) -> str:
+    listed = "\n".join(f"  - {p}" for p in leaks)
+    return (
+        f"Content under a content stage (kb/, raw/, work/, reports/) changed between {since} "
+        f"and {until} through a path that is not stack-owned:\n{listed}\n\n"
+        "That is upstream content (or an equivalent local change) that reached this range "
+        "outside of a stack-owned path - inspect it before trusting this range as machinery-only."
+    )
+
+
+def _verify_success_message(stack_moved: list[str], since: str, until: str) -> str:
+    if not stack_moved:
+        return f"No content changed between {since} and {until} under kb/, raw/, work/, reports/."
+    listed = "\n".join(f"  - {p}" for p in stack_moved)
+    return (
+        f"Clean: only stack-owned paths changed under kb/, raw/, work/, reports/ between "
+        f"{since} and {until}:\n{listed}"
+    )
+
+
+@app.command("verify")
+def verify_command(
+    since: str = typer.Option(..., "--since", help="Git revision to compare from"),
+    until: str = typer.Option("HEAD", "--until", help="Git revision to compare to"),
+):
+    """Check that nothing under a content stage changed between --since and
+    --until except through a stack-owned path. Read-only, and exempt from the
+    Iteration Budget Gate - the same treatment `migrate verify` gets, for the
+    same reason: a check an agent has to ration is a check that gets skipped."""
+    leaks = _content_leaks(since, until)
+    if leaks:
+        fail(_verify_failure_message(leaks, since, until))
+        return
+    success(_verify_success_message(_stack_paths_changed(since, until), since, until))

tools/chemenu/kb_state.py

@@ -129,21 +129,27 @@ def migrations_dir() -> Path:
     return config.INSTRUCTIONS_DIR / MIGRATIONS_SUBDIR
 
 
-def load_migrations() -> list[Migration]:
+def load_migrations(directory: Optional[Path] = None) -> list[Migration]:
-    """Every migration document, sorted by target version.
+    """Every migration document under `directory`, sorted by target version.
 
-    A malformed one is skipped rather than fatal here - `instructions verify`
+    `directory` defaults to this instance's own `instructions/migrations/`.
-    is what reports it, and `migrate status` staying usable while one document
+    `dist upgrade` (Gitea #7) passes the *new* tree's migrations directory
-    is broken is worth more than a second error path.
+    instead: the migrations owed after an upgrade are documented in the
+    machinery being installed, not in the one still on disk - an old instance
+    cannot know a new version's migration chain by reading its own tree.
+
+    A malformed document is skipped rather than fatal here - `instructions
+    verify` is what reports it, and `migrate status` staying usable while one
+    document is broken is worth more than a second error path.
     """
     from chemenu.frontmatter_io import read_page
 
-    directory = migrations_dir()
+    base = directory if directory is not None else migrations_dir()
-    if not directory.is_dir():
+    if not base.is_dir():
         return []
 
     migrations: list[Migration] = []
-    for path in sorted(directory.glob("*.md")):
+    for path in sorted(base.glob("*.md")):
         try:
             frontmatter, _ = read_page(path)
         except Exception:  # noqa: BLE001 - a broken document is verify's finding, not ours
@@ -232,25 +238,60 @@ def next_link(
 
 # --- what this instance changed about what it was given --------------------
 
+# What `compare_against_stamp` answers for one path: present and matching its
+# recorded digest, present but not matching, or gone entirely. `dist upgrade`
+# needs the three-way answer to tell a locally deleted file from a locally
+# edited one; `divergent_files` (below) only ever needed the yes/no of
+# "does this count as diverged", which both `MODIFIED` and `DELETED` answer
+# the same way.
+UNCHANGED = "unchanged"
+MODIFIED = "modified"
+DELETED = "deleted"
+
+
+def compare_against_stamp(stamp_files: dict, root: Optional[Path] = None) -> dict[str, str]:
+    """Classify every path in `stamp_files` (relative -> recorded sha256, the
+    shape of a release stamp's own `files` block) against what is actually on
+    disk under `root` - `UNCHANGED`, `MODIFIED`, or `DELETED`.
+
+    `root` defaults to `config.ROOT`. The general form `divergent_files` is
+    built on: that function only ever asks the question against this
+    instance's own tree, but `dist upgrade` (Gitea #7) asks it against an
+    already-installed tree while planning what to write, and a *second* time
+    against the tree it just wrote, before recording the new stamp - two trees
+    neither of which is necessarily `config.ROOT`.
+    """
+    import hashlib
+
+    base = root if root is not None else config.ROOT
+    result: dict[str, str] = {}
+    for relative, digest in sorted(stamp_files.items()):
+        path = base / relative
+        if not path.is_file():
+            result[relative] = DELETED
+            continue
+        current = "sha256:" + hashlib.sha256(path.read_bytes()).hexdigest()
+        result[relative] = UNCHANGED if current == digest else MODIFIED
+    return result
+
 
 def divergent_files() -> Optional[list[str]]:
     """Files whose content no longer matches the release this instance installed.
 
     Reads the per-file sha256 in `.wikitool-release.json`, which `dist export`
-    has been writing since the stamp existed and which nothing has read until
+    has been writing since the stamp existed. Its own docstring says why it is
-    now. Its own docstring says why it is there: it is the only way a later
+    there: it is the only way a later upgrade can tell a file the instance
-    upgrade can tell a file the instance *edited* from one it merely *received*.
+    *edited* from one it merely *received* - `dist upgrade` (Gitea #7) is that
+    later upgrade, built on the general `compare_against_stamp` above.
 
-    That distinction is what makes an `offered` migration actionable. The stack
+    That distinction is also what makes an `offered` migration actionable. The
-    proposing a better `entity` template needs to know whether it may be copied
+    stack proposing a better `entity` template needs to know whether it may be
-    over or whether the instance has its own version that a person has to
+    copied over or whether the instance has its own version that a person has
-    reconcile - and only the recorded hash can answer that.
+    to reconcile - and only the recorded hash can answer that.
 
     Returns None when the question is unanswerable (a development tree, which
     carries no stamp), which is different from `[]` (nothing diverged).
     """
-    import hashlib
-
     from chemenu import version as version_mod
 
     try:
@@ -263,13 +304,5 @@ def divergent_files() -> Optional[list[str]]:
     if not isinstance(recorded, dict):
         return None
 
-    divergent: list[str] = []
+    statuses = compare_against_stamp(recorded)
-    for relative, digest in sorted(recorded.items()):
+    return [relative for relative, status in statuses.items() if status != UNCHANGED]
-        path = config.ROOT / relative
-        if not path.is_file():
-            divergent.append(relative)
-            continue
-        current = "sha256:" + hashlib.sha256(path.read_bytes()).hexdigest()
-        if current != digest:
-            divergent.append(relative)
-    return divergent

tools/chemenu/ownership.py

@@ -0,0 +1,87 @@
+"""The ownership boundary for a path under a content stage: does it belong to
+the *stack* (ships with every distribution, wins over local content when a
+private instance merges from a public upstream) or to the *instance* (never
+ships filled, wins over the upstream's version)?
+
+One predicate, so `dist_cmd.py` (export) and `upstream_cmd.py` (merge/verify)
+answer the same question about the same paths instead of each keeping its own
+literal list that can drift out of sync with the other - see AGENTS.md
+invariant 8, and Gitea #30 for the incident that made the drift concrete
+(the private-instance merge procedure hardcoded a three-path list that
+`dist_cmd.py` had already outgrown).
+"""
+from __future__ import annotations
+
+# The stages whose content belongs to *this instance*, not the stack. Mirrors
+# the sentence .gitignore already makes about raw/, kb/ and work/ being the
+# repo's content, plus reports/ - only reports/CONTRACT.md is tracked there,
+# the rest is gitignored, so restoring it is a no-op today. It stays in the
+# set anyway: a set that is "almost" this one is the beginning of the same
+# drift this module exists to end.
+CONTENT_STAGES = ("kb", "raw", "work", "reports")
+
+# Bare filenames `dist export` overwrites with a fresh stub rather than
+# shipping the stack's own copy. Not stack-owned: an upstream merge takes the
+# *local* side for these (they are the instance's own log/placeholder),
+# while `dist export` writes a brand-new one regardless of either side.
+EXPORT_STUB_NAMES = ("log.md", ".gitkeep")
+
+# The single machinery filename directly under a content stage's own root.
+_STAGE_CONTRACT_NAME = "CONTRACT.md"
+
+
+def is_stack_owned(relative: str) -> bool:
+    """Whether `relative` - a path under a content stage, e.g. "kb/CONTRACT.md"
+    or "kb/entities/COLLECTION.md.template" - is machinery: it ships with
+    every distribution, and it is the side an upstream merge keeps.
+
+    True for exactly two shapes:
+
+    - `<stage>/CONTRACT.md`, directly under a content stage's own root. Not
+      recursive: `kb/<collection>/COLLECTION.md` sits one level deeper and is
+      instance-owned (see kb/CONTRACT.md's collection-ownership split).
+    - Any path under a content stage ending in `.template` - by construction
+      the stack's own copy of something the instance adopts by renaming
+      (`kb/CONVENTIONS.md.template` and every `kb/<name>/COLLECTION.md.template`
+      today; a future stack-owned template under a content stage falls under
+      this rule automatically, with no code change here).
+
+    False for everything else under a content stage, `EXPORT_STUB_NAMES`
+    included - those are handled separately by whichever caller cares about
+    them, because the two callers disagree about which side wins for a stub.
+    """
+    parts = relative.split("/")
+    if len(parts) < 2 or parts[0] not in CONTENT_STAGES:
+        return False
+    if relative.endswith(".template"):
+        return True
+    return len(parts) == 2 and parts[1] == _STAGE_CONTRACT_NAME
+
+
+def is_export_stub(name: str) -> bool:
+    """Whether `name` (a bare filename, not a path) is one `dist export`
+    overwrites with a fresh stub of its own rather than shipping verbatim."""
+    return name in EXPORT_STUB_NAMES
+
+
+# Root-relative paths `dist export` seeds once, from a template it owns, and
+# which the instance owns exclusively from that point on. `dist upgrade`
+# (Gitea #7) must never overwrite them, even though they sit in the release
+# stamp's `files` block like any other planned file - the same shape as
+# `EXPORT_STUB_NAMES` above, but keyed by full path rather than bare filename,
+# since nothing else at the repo root gets this treatment and a bare-filename
+# match would be too broad here.
+#
+# `.wikitool-kb.json` is `migrate done`'s state file: an upgrade that resets it
+# declares a content shape nobody actually produced. `CHANGES.md` is the
+# instance's own changelog, not the stack's - `dist export` seeds it from a
+# blank template (`dist_templates/CHANGES.md`) the same way it seeds
+# `kb/log.md`, and overwriting it on upgrade would erase every entry the
+# instance ever wrote for itself.
+UPGRADE_PRESERVED_PATHS = (".wikitool-kb.json", "CHANGES.md")
+
+
+def is_upgrade_preserved(relative: str) -> bool:
+    """Whether `relative` (a plan-relative path from the repo root, e.g.
+    "CHANGES.md") is one `dist upgrade` must never write."""
+    return relative in UPGRADE_PRESERVED_PATHS

tools/chemenu/tests/test_dist_upgrade.py

@@ -0,0 +1,386 @@
+"""Tests for `wikitool dist upgrade`: classification against the locally
+installed release stamp, the write set, migration-chain reporting without
+execution, and every refusal before anything is written. See Gitea #7."""
+from __future__ import annotations
+
+import hashlib
+import json
+import subprocess
+import tarfile
+from pathlib import Path
+
+import pytest
+import typer
+
+from chemenu import config, kb_state, version as version_mod
+from chemenu.commands import dist_cmd
+
+
+def _digest(text: str) -> str:
+    return "sha256:" + hashlib.sha256(text.encode("utf-8")).hexdigest()
+
+
+def _write_stamp(path: Path, version: str, files: dict[str, str]) -> None:
+    path.write_text(
+        json.dumps(
+            {
+                "schema": version_mod.STAMP_SCHEMA,
+                "version": version,
+                "exported_at": "2026-01-01",
+                "source_repo": None,
+                "source_commit": None,
+                "release_url": None,
+                "update_url": version_mod.DEFAULT_UPDATE_URL,
+                "files": files,
+            },
+            indent=2,
+        ),
+        encoding="utf-8",
+    )
+
+
+def write_migration(directory: Path, target: str, slug: str) -> None:
+    directory.mkdir(parents=True, exist_ok=True)
+    (directory / f"{target}-{slug}.md").write_text(
+        "---\n"
+        "type: types/instruction.md\n"
+        f"name: {target}-{slug}\n"
+        f"description: Migration to {target}.\n"
+        "manual: true\n"
+        f"migrates_to: {target}\n"
+        "migration_kind: assisted\n"
+        "obligation: required\n"
+        "---\n\n# Migration\n\nSteps.\n",
+        encoding="utf-8",
+    )
+
+
+def set_kb_version(root: Path, version: str) -> None:
+    (root / kb_state.KB_STATE_FILENAME).write_text(
+        json.dumps({"schema": 1, "kb_version": version, "applied": []}), encoding="utf-8"
+    )
+
+
+@pytest.fixture
+def instance(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Path:
+    """A minimal tarball instance: VERSION 1.0.0, a local release stamp
+    recording two tracked files exactly as installed, content stays at
+    1.0.0 with nothing outstanding, and no .git directory (the WARN path
+    for the dirty-tree check)."""
+    root = tmp_path / "instance"
+    root.mkdir()
+    monkeypatch.setattr(config, "ROOT", root)
+
+    (root / "VERSION").write_text("1.0.0\n", encoding="utf-8")
+    (root / "AGENTS.md").write_text("core\n", encoding="utf-8")
+    (root / "tools").mkdir()
+    (root / "tools" / "wikitool").write_text("#!/bin/sh\n", encoding="utf-8")
+
+    files = {
+        "AGENTS.md": _digest("core\n"),
+        "tools/wikitool": _digest("#!/bin/sh\n"),
+    }
+    _write_stamp(root / version_mod.RELEASE_STAMP_FILENAME, "1.0.0", files)
+    set_kb_version(root, "1.0.0")
+    return root
+
+
+def _release(tmp_path: Path, name: str, version: str, files_content: dict[str, str]) -> Path:
+    """A second, independent tree shaped like a `dist export` output: VERSION,
+    a release stamp whose `files` block matches `files_content` exactly, and
+    the files themselves."""
+    root = tmp_path / name
+    root.mkdir()
+    (root / "VERSION").write_text(f"{version}\n", encoding="utf-8")
+    files: dict[str, str] = {}
+    for relative, content in files_content.items():
+        path = root / relative
+        path.parent.mkdir(parents=True, exist_ok=True)
+        path.write_text(content, encoding="utf-8")
+        files[relative] = _digest(content)
+    _write_stamp(root / version_mod.RELEASE_STAMP_FILENAME, version, files)
+    return root
+
+
+# --- classification / dry-run -----------------------------------------------
+
+
+def test_dry_run_classifies_every_case_and_writes_nothing(instance, tmp_path):
+    (instance / "AGENTS.md").write_text("locally edited\n", encoding="utf-8")
+    (instance / "tools" / "wikitool").unlink()
+
+    release = _release(
+        tmp_path, "release", "1.1.0",
+        {
+            "AGENTS.md": "core\n",             # locally modified
+            "tools/wikitool": "#!/bin/sh\n",   # locally deleted
+            "types/entity.md": "new page type\n",  # new in the release
+        },
+    )
+
+    dist_cmd.run_upgrade(release, dry_run=True)
+
+    assert (instance / "AGENTS.md").read_text(encoding="utf-8") == "locally edited\n"
+    assert not (instance / "tools" / "wikitool").exists()
+    assert not (instance / "types" / "entity.md").exists()
+    assert json.loads((instance / version_mod.RELEASE_STAMP_FILENAME).read_text())["version"] == "1.0.0"
+
+
+def test_removed_file_is_reported_and_left_alone_without_prune(instance, tmp_path):
+    release = _release(tmp_path, "release", "1.1.0", {"AGENTS.md": "core\n"})
+    # tools/wikitool is in the old stamp but absent from the new one.
+    dist_cmd.run_upgrade(release, dry_run=True)
+    assert (instance / "tools" / "wikitool").is_file()
+
+
+# --- local changes are never silently overwritten ---------------------------
+
+
+def test_locally_modified_file_blocks_the_upgrade_by_default(instance, tmp_path):
+    (instance / "AGENTS.md").write_text("locally edited\n", encoding="utf-8")
+    release = _release(
+        tmp_path, "release", "1.1.0",
+        {"AGENTS.md": "core v2\n", "tools/wikitool": "#!/bin/sh\n"},
+    )
+    with pytest.raises(typer.Exit) as excinfo:
+        dist_cmd.run_upgrade(release)
+    assert excinfo.value.exit_code == 1
+    assert (instance / "AGENTS.md").read_text(encoding="utf-8") == "locally edited\n"
+    assert json.loads((instance / version_mod.RELEASE_STAMP_FILENAME).read_text())["version"] == "1.0.0"
+
+
+def test_locally_deleted_file_blocks_the_upgrade_by_default(instance, tmp_path):
+    (instance / "tools" / "wikitool").unlink()
+    release = _release(
+        tmp_path, "release", "1.1.0",
+        {"AGENTS.md": "core\n", "tools/wikitool": "#!/bin/sh v2\n"},
+    )
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(release)
+    assert not (instance / "tools" / "wikitool").exists()
+
+
+def test_keep_local_proceeds_and_leaves_the_changed_file_untouched(instance, tmp_path):
+    (instance / "AGENTS.md").write_text("locally edited\n", encoding="utf-8")
+    release = _release(
+        tmp_path, "release", "1.1.0",
+        {"AGENTS.md": "core v2\n", "tools/wikitool": "#!/bin/sh\n", "types/entity.md": "new\n"},
+    )
+    dist_cmd.run_upgrade(release, keep_local=True)
+
+    # The locally changed file is untouched...
+    assert (instance / "AGENTS.md").read_text(encoding="utf-8") == "locally edited\n"
+    # ...but everything unchanged/new was still written.
+    assert (instance / "tools" / "wikitool").read_text(encoding="utf-8") == "#!/bin/sh\n"
+    assert (instance / "types" / "entity.md").read_text(encoding="utf-8") == "new\n"
+    assert json.loads((instance / version_mod.RELEASE_STAMP_FILENAME).read_text())["version"] == "1.1.0"
+
+
+# --- the write set -----------------------------------------------------------
+
+
+def test_unchanged_and_new_files_are_written_silently(instance, tmp_path):
+    release = _release(
+        tmp_path, "release", "1.1.0",
+        {"AGENTS.md": "core\n", "tools/wikitool": "#!/bin/sh\n", "types/entity.md": "new\n"},
+    )
+    dist_cmd.run_upgrade(release)
+    assert (instance / "AGENTS.md").read_text(encoding="utf-8") == "core\n"
+    assert (instance / "types" / "entity.md").read_text(encoding="utf-8") == "new\n"
+    stamp = json.loads((instance / version_mod.RELEASE_STAMP_FILENAME).read_text())
+    assert stamp["version"] == "1.1.0"
+    assert stamp["files"]["types/entity.md"] == _digest("new\n")
+
+
+@pytest.mark.parametrize("preserved", [".wikitool-kb.json", "CHANGES.md", "kb/log.md", "raw/notes/.gitkeep"])
+def test_seeded_once_paths_are_never_written_even_if_the_release_stamp_lists_them(
+    instance, tmp_path, preserved
+):
+    """The write set is the new stamp's `files` block minus what an export
+    re-seeds every time or seeds once and the instance owns from then on -
+    this is the AGENTS.md invariant 8 test: no separate literal list here,
+    only `chemenu.ownership`."""
+    (instance / "CHANGES.md").write_text("instance's own changelog\n", encoding="utf-8")
+    (instance / kb_state.KB_STATE_FILENAME).write_text(
+        json.dumps({"schema": 1, "kb_version": "1.0.0", "applied": [{"migration": "x"}]}),
+        encoding="utf-8",
+    )
+    release = _release(
+        tmp_path, "release", "1.1.0",
+        {
+            "AGENTS.md": "core\n",
+            "tools/wikitool": "#!/bin/sh\n",
+            preserved: "a fresh stub from the new release\n",
+        },
+    )
+    dist_cmd.run_upgrade(release)
+    if preserved == "CHANGES.md":
+        assert (instance / preserved).read_text(encoding="utf-8") == "instance's own changelog\n"
+    elif preserved == ".wikitool-kb.json":
+        state = json.loads((instance / preserved).read_text())
+        assert state["applied"] == [{"migration": "x"}]
+    else:
+        assert not (instance / preserved).exists()
+
+
+# --- migration chain: reported, never run -----------------------------------
+
+
+def test_migration_chain_is_reported_but_never_executed(instance, tmp_path):
+    release = _release(
+        tmp_path, "release", "1.1.0",
+        {"AGENTS.md": "core\n", "tools/wikitool": "#!/bin/sh\n"},
+    )
+    write_migration(release / "instructions" / "migrations", "1.1.0", "some-change")
+
+    dist_cmd.run_upgrade(release)
+
+    # The chain is reported, not applied: kb_version has not moved.
+    assert kb_state.read_kb_version().base == version_mod.Version(1, 0, 0)
+
+
+def test_outstanding_local_migration_blocks_before_touching_the_source(instance, tmp_path):
+    """A migration owed against the *installed* machinery must be finished
+    first - the source is never even opened."""
+    migrations = instance / "instructions" / "migrations"
+    write_migration(migrations, "1.0.0", "not-yet-done")
+    monkey_target = instance / "does-not-exist"  # never read if this check fires first
+
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(monkey_target)
+
+
+# --- preconditions -----------------------------------------------------------
+
+
+def test_missing_local_stamp_blocks(instance, tmp_path):
+    (instance / version_mod.RELEASE_STAMP_FILENAME).unlink()
+    release = _release(tmp_path, "release", "1.1.0", {"AGENTS.md": "core\n"})
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(release)
+
+
+def test_missing_kb_version_blocks(instance, tmp_path):
+    (instance / kb_state.KB_STATE_FILENAME).unlink()
+    release = _release(tmp_path, "release", "1.1.0", {"AGENTS.md": "core\n"})
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(release)
+
+
+def test_prerelease_source_is_refused_without_pre_flag(instance, tmp_path):
+    release = _release(tmp_path, "release", "1.1.0-beta.1", {"AGENTS.md": "core\n"})
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(release)
+    assert json.loads((instance / version_mod.RELEASE_STAMP_FILENAME).read_text())["version"] == "1.0.0"
+
+
+def test_pre_flag_allows_a_prerelease_source(instance, tmp_path):
+    release = _release(
+        tmp_path, "release", "1.1.0-beta.1",
+        {"AGENTS.md": "core\n", "tools/wikitool": "#!/bin/sh\n"},
+    )
+    dist_cmd.run_upgrade(release, allow_pre=True)
+    assert json.loads((instance / version_mod.RELEASE_STAMP_FILENAME).read_text())["version"] == "1.1.0-beta.1"
+
+
+def test_downgrade_is_refused(instance, tmp_path):
+    release = _release(tmp_path, "release", "0.9.0", {"AGENTS.md": "core\n"})
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(release)
+
+
+def test_equal_version_is_a_noop(instance, tmp_path):
+    release = _release(tmp_path, "release", "1.0.0", {"AGENTS.md": "core\n"})
+    dist_cmd.run_upgrade(release)  # must not raise
+    assert json.loads((instance / version_mod.RELEASE_STAMP_FILENAME).read_text())["version"] == "1.0.0"
+
+
+def test_dirty_working_tree_blocks(instance, tmp_path):
+    subprocess.run(["git", "init", "-q", "-b", "main"], cwd=instance, check=True)
+    subprocess.run(["git", "config", "user.name", "Fixture Author"], cwd=instance, check=True)
+    subprocess.run(["git", "config", "user.email", "fixture@example.invalid"], cwd=instance, check=True)
+    (instance / "untracked.txt").write_text("dirty\n", encoding="utf-8")
+
+    release = _release(tmp_path, "release", "1.1.0", {"AGENTS.md": "core\n"})
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(release)
+    assert not (instance / "types").exists()
+
+
+def test_source_that_does_not_exist_is_refused(instance, tmp_path):
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(tmp_path / "nowhere")
+
+
+# --- prune -------------------------------------------------------------------
+
+
+def test_prune_removes_only_removed_files_still_unchanged_since_install(instance, tmp_path):
+    (instance / "extra.txt").write_text("shipped once, edited since\n", encoding="utf-8")
+    old_stamp = json.loads((instance / version_mod.RELEASE_STAMP_FILENAME).read_text())
+    old_stamp["files"]["extra.txt"] = _digest("shipped once, unedited\n")  # deliberately stale
+    old_stamp["files"]["gone.txt"] = _digest("also shipped once\n")
+    (instance / version_mod.RELEASE_STAMP_FILENAME).write_text(json.dumps(old_stamp), encoding="utf-8")
+    (instance / "gone.txt").write_text("also shipped once\n", encoding="utf-8")
+
+    release = _release(
+        tmp_path, "release", "1.1.0",
+        {"AGENTS.md": "core\n", "tools/wikitool": "#!/bin/sh\n"},
+    )
+    dist_cmd.run_upgrade(release, prune=True)
+
+    # gone.txt matched its recorded digest -> pruned.
+    assert not (instance / "gone.txt").exists()
+    # extra.txt was locally edited relative to its recorded digest -> kept.
+    assert (instance / "extra.txt").read_text(encoding="utf-8") == "shipped once, edited since\n"
+
+
+# --- tarball sources ----------------------------------------------------------
+
+
+def _pack(release_dir: Path, archive: Path) -> None:
+    with tarfile.open(archive, "w:gz") as tf:
+        tf.add(release_dir, arcname=release_dir.name)
+
+
+def test_tarball_with_more_than_one_top_level_entry_is_refused(instance, tmp_path):
+    scratch = tmp_path / "scratch"
+    (scratch / "a").mkdir(parents=True)
+    (scratch / "b").mkdir(parents=True)
+    (scratch / "a" / "x.txt").write_text("x\n", encoding="utf-8")
+    (scratch / "b" / "y.txt").write_text("y\n", encoding="utf-8")
+    archive = tmp_path / "bad.tar.gz"
+    with tarfile.open(archive, "w:gz") as tf:
+        tf.add(scratch / "a", arcname="a")
+        tf.add(scratch / "b", arcname="b")
+
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(archive)
+
+
+def test_tarball_source_is_extracted_and_applied(instance, tmp_path):
+    release_dir = _release(
+        tmp_path, "chemenu-stack-1.1.0", "1.1.0",
+        {"AGENTS.md": "core\n", "tools/wikitool": "#!/bin/sh\n"},
+    )
+    archive = tmp_path / "chemenu-stack-1.1.0.tar.gz"
+    _pack(release_dir, archive)
+
+    dist_cmd.run_upgrade(archive)
+
+    assert (instance / "AGENTS.md").read_text(encoding="utf-8") == "core\n"
+    assert json.loads((instance / version_mod.RELEASE_STAMP_FILENAME).read_text())["version"] == "1.1.0"
+
+
+def test_tarball_sha256_sidecar_mismatch_is_refused(instance, tmp_path):
+    release_dir = _release(
+        tmp_path, "chemenu-stack-1.1.0", "1.1.0", {"AGENTS.md": "core\n"}
+    )
+    archive = tmp_path / "chemenu-stack-1.1.0.tar.gz"
+    _pack(release_dir, archive)
+    (archive.with_name(archive.name + ".sha256")).write_text(
+        "0" * 64 + "  chemenu-stack-1.1.0.tar.gz\n", encoding="utf-8"
+    )
+
+    with pytest.raises(typer.Exit):
+        dist_cmd.run_upgrade(archive)

tools/chemenu/tests/test_upstream_cmd.py

@@ -0,0 +1,470 @@
+"""Tests for `wikitool upstream merge`/`upstream verify` - the code procedure
+that replaces private-instance.md's prose merge script (Gitea #30).
+
+Two real git repos stand in for a private instance (`repo`, remote name
+`upstream`) and the public repo it takes updates from (`upstream`, a plain
+repo committed to directly - a fetch-only remote does not need to be bare for
+`git fetch` to work against it). Each scenario diverges the two by committing
+independently on each side, exactly like a real fetch-only upstream would.
+"""
+from __future__ import annotations
+
+import subprocess
+
+import pytest
+import typer
+
+from chemenu import config, ownership
+from chemenu.commands import git_publish, upstream_cmd
+
+
+def _git(root, *args):
+    result = subprocess.run(["git", *args], cwd=root, capture_output=True, text=True)
+    assert result.returncode == 0, result.stderr
+    return result
+
+
+def _write(root, relative, content):
+    path = root / relative
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_text(content, encoding="utf-8")
+
+
+def _commit(root, message):
+    _git(root, "add", "-A")
+    _git(root, "commit", "-m", message)
+
+
+@pytest.fixture
+def two_repos(tmp_path, monkeypatch):
+    """`repo`, a private instance, with a fetch-only `upstream` remote pointing
+    at a second, independent repo. Both start from the same seed commit -
+    kb/CONTRACT.md, kb/CONVENTIONS.md(.template), kb/entities/COLLECTION.md,
+    raw/CONTRACT.md, work/CONTRACT.md, reports/CONTRACT.md, and one tools/
+    file - which is what a private instance looks like right after the
+    private-instance.md setup: the tracked machinery, plus its own filled
+    instance files layered on top.
+    """
+    seed = tmp_path / "seed"
+    seed.mkdir()
+    _git(seed, "init", "-b", "main")
+    _git(seed, "config", "user.name", "Seed")
+    _git(seed, "config", "user.email", "seed@example.com")
+    # .wikitool-remotes.json is gitignored in the real repo (it is per-checkout,
+    # see config.PUBLISH_REMOTES_FILENAME) - without this, dropping one into the
+    # fixture during a test would show up as an untracked file and trip the
+    # dirty-working-tree precondition for a reason that has nothing to do with
+    # what that test is checking.
+    # Mirrors the real .gitignore in the two ways that matter here:
+    # `.wikitool-remotes.json` is per-checkout (dropping one in during a test
+    # must not read as a dirty tree), and `reports/` is derived output that is
+    # ignored except for its contract - which is what makes a content stage
+    # able to hold local, non-recomputable data a merge must not touch.
+    _write(
+        seed,
+        ".gitignore",
+        f"/{config.PUBLISH_REMOTES_FILENAME}\n/reports/*\n!/reports/CONTRACT.md\n",
+    )
+    _write(seed, "kb/CONTRACT.md", "stack kb contract v1\n")
+    _write(seed, "kb/CONVENTIONS.md.template", "template v1\n")
+    _write(seed, "kb/CONVENTIONS.md", "instance conventions v1\n")
+    _write(seed, "kb/entities/COLLECTION.md", "instance collection contract v1\n")
+    _write(seed, "kb/Both.md", "page both sides delete\n")
+    _write(seed, "kb/ToDelete.md", "page the instance will delete\n")
+    _write(seed, "kb/RegularPage.md", "an ordinary page neither side has touched yet\n")
+    _write(seed, "raw/CONTRACT.md", "raw contract v1\n")
+    _write(seed, "work/CONTRACT.md", "work contract v1\n")
+    _write(seed, "reports/CONTRACT.md", "reports contract v1\n")
+    _write(seed, "tools/wikitool.py", "line one\nline two\nline three\n")
+    _commit(seed, "seed")
+
+    upstream = tmp_path / "upstream"
+    subprocess.run(["git", "clone", str(seed), str(upstream)], check=True, capture_output=True)
+    _git(upstream, "config", "user.name", "Upstream")
+    _git(upstream, "config", "user.email", "upstream@example.com")
+
+    # Cloned from `upstream`, not from `seed` directly: the remote (renamed
+    # below) must resolve to the path this fixture actually commits new
+    # upstream state into, or a later `git fetch upstream main` silently
+    # fetches from `seed` instead and never sees anything new.
+    repo = tmp_path / "repo"
+    subprocess.run(["git", "clone", str(upstream), str(repo)], check=True, capture_output=True)
+    _git(repo, "config", "user.name", "Test")
+    _git(repo, "config", "user.email", "test@example.com")
+    _git(repo, "remote", "rename", "origin", "upstream")
+
+    monkeypatch.setattr(config, "ROOT", repo)
+    monkeypatch.setenv("WIKITOOL_SESSION_ID", "test-session")
+    return upstream, repo
+
+
+def _merge(**overrides):
+    kwargs = dict(remote="upstream", branch="main", no_fetch=False)
+    kwargs.update(overrides)
+    upstream_cmd.merge_command(**kwargs)
+
+
+# --- the four restbefund regressions, plus the baseline table from the issue ---
+
+
+def test_upstream_edit_of_a_page_the_instance_deleted_does_not_land(two_repos):
+    upstream, repo = two_repos
+    _git(repo, "rm", "-q", "kb/ToDelete.md")
+    _commit(repo, "instance deletes ToDelete")
+
+    _write(upstream, "kb/ToDelete.md", "upstream edited it after the instance deleted it\n")
+    _commit(upstream, "upstream edits ToDelete")
+
+    _merge()
+
+    assert not (repo / "kb/ToDelete.md").exists()
+
+
+def test_upstream_new_page_does_not_land(two_repos):
+    upstream, repo = two_repos
+    _write(upstream, "kb/NewPage.md", "a demo page the upstream added\n")
+    _commit(upstream, "upstream adds NewPage")
+
+    _merge()
+
+    assert not (repo / "kb/NewPage.md").exists()
+
+
+def test_page_deleted_on_both_sides_is_a_noop(two_repos):
+    upstream, repo = two_repos
+    _git(repo, "rm", "-q", "kb/Both.md")
+    _commit(repo, "instance deletes Both")
+    _git(upstream, "rm", "-q", "kb/Both.md")
+    _commit(upstream, "upstream deletes Both")
+
+    _merge()  # must not raise
+
+    assert not (repo / "kb/Both.md").exists()
+
+
+def test_kb_contract_change_lands(two_repos):
+    upstream, repo = two_repos
+    _write(upstream, "kb/CONTRACT.md", "stack kb contract v2\n")
+    _commit(upstream, "upstream changes kb/CONTRACT.md")
+
+    _merge()
+
+    assert (repo / "kb/CONTRACT.md").read_text(encoding="utf-8") == "stack kb contract v2\n"
+
+
+def test_conventions_template_change_lands_local_conventions_untouched(two_repos):
+    upstream, repo = two_repos
+    _write(upstream, "kb/CONVENTIONS.md.template", "template v2\n")
+    _commit(upstream, "upstream changes the conventions template")
+
+    _merge()
+
+    assert (repo / "kb/CONVENTIONS.md.template").read_text(encoding="utf-8") == "template v2\n"
+    assert (repo / "kb/CONVENTIONS.md").read_text(encoding="utf-8") == "instance conventions v1\n"
+
+
+def test_collection_contract_change_does_not_land(two_repos):
+    """A COLLECTION.md is instance-owned since #39 - one level deeper than
+    `<stage>/CONTRACT.md`, so `is_stack_owned` must say no to it."""
+    upstream, repo = two_repos
+    _write(repo, "kb/entities/COLLECTION.md", "instance collection contract v2 (local)\n")
+    _commit(repo, "instance rewrites its own collection contract")
+
+    _write(upstream, "kb/entities/COLLECTION.md", "upstream collection contract v2\n")
+    _commit(upstream, "upstream changes the default collection contract")
+
+    _merge()
+
+    assert (repo / "kb/entities/COLLECTION.md").read_text(encoding="utf-8") == (
+        "instance collection contract v2 (local)\n"
+    )
+
+
+def test_upstream_deletion_of_a_contract_file_lands(two_repos):
+    """Restbefund 2: a machinery file the upstream deleted must not silently
+    survive because `git checkout MERGE_HEAD -- <path>` has nothing to check
+    out."""
+    upstream, repo = two_repos
+    _git(upstream, "rm", "-q", "raw/CONTRACT.md")
+    _commit(upstream, "upstream drops raw/CONTRACT.md")
+
+    _merge()
+
+    assert not (repo / "raw/CONTRACT.md").exists()
+
+
+def test_new_stack_template_under_a_content_stage_lands(two_repos):
+    """Restbefund 4: a brand-new stack-owned path the local tree has never
+    seen must still be recognised by the predicate, not by a literal list."""
+    upstream, repo = two_repos
+    _write(upstream, "kb/GLOSSARY.md.template", "a stack-owned template that never existed before\n")
+    _commit(upstream, "upstream adds a new template")
+
+    _merge()
+
+    assert (repo / "kb/GLOSSARY.md.template").read_text(encoding="utf-8") == (
+        "a stack-owned template that never existed before\n"
+    )
+
+
+def test_open_workshop_run_files_do_not_land(two_repos):
+    upstream, repo = two_repos
+    _write(upstream, "work/some-run/README.md", "an in-progress workshop run\n")
+    _commit(upstream, "upstream ships an open work/ run")
+
+    _merge()
+
+    assert not (repo / "work/some-run").exists()
+
+
+def test_merge_keeps_ignored_local_data_under_a_content_stage(two_repos):
+    """`reports/` is gitignored except its contract, so a content stage's
+    working tree holds local data that is in no git tree and is not
+    recomputable - the telemetry traces `eval score` reads, saved eval
+    reports, past lint reports. Forcing the stage back to the local side must
+    not take those out as collateral: this instance had 497 trace directories
+    under reports/telemetry/ when the first version of this command wiped the
+    stage wholesale."""
+    upstream, repo = two_repos
+    _write(repo, "reports/telemetry/session-a/trace.jsonl", '{"event": "local"}\n')
+    _write(repo, "reports/Lint Report 2026-09-04.md", "a local lint report\n")
+    assert _git(repo, "status", "--porcelain").stdout == ""  # ignored, so the tree is clean
+
+    _write(upstream, "kb/CONTRACT.md", "stack kb contract v2\n")
+    _commit(upstream, "upstream changes kb/CONTRACT.md")
+
+    _merge()
+
+    assert (repo / "reports/telemetry/session-a/trace.jsonl").read_text(encoding="utf-8") == (
+        '{"event": "local"}\n'
+    )
+    assert (repo / "reports/Lint Report 2026-09-04.md").exists()
+    assert (repo / "reports/CONTRACT.md").read_text(encoding="utf-8") == "reports contract v1\n"
+
+
+def test_upstream_content_under_a_stage_absent_from_head_does_not_land(two_repos):
+    """The stage guard must not rest on the local side happening to track
+    something under that stage: an instance whose `work/` holds no tracked
+    file at all must still not receive the upstream's open run."""
+    upstream, repo = two_repos
+    _git(repo, "rm", "-q", "work/CONTRACT.md")
+    _commit(repo, "instance has nothing tracked under work/")
+
+    _write(upstream, "work/some-run/README.md", "an in-progress workshop run\n")
+    _commit(upstream, "upstream ships an open work/ run")
+
+    _merge()
+
+    assert not (repo / "work/some-run").exists()
+
+
+def test_one_upstream_commit_mixing_every_case_at_once(two_repos):
+    """The acceptance test from the issue: a single upstream commit that edits
+    a page the instance deleted, adds a new page, deletes an untouched page,
+    changes a stack contract, changes a template, and deletes a different
+    stack contract - all at once, all restored or discarded correctly by one
+    `upstream merge` call."""
+    upstream, repo = two_repos
+    _git(repo, "rm", "-q", "kb/ToDelete.md")
+    _commit(repo, "instance deletes ToDelete")
+
+    _write(upstream, "kb/ToDelete.md", "upstream edited it after the instance deleted it\n")
+    _write(upstream, "kb/BrandNewPage.md", "a demo page the upstream added\n")
+    _git(upstream, "rm", "-q", "kb/RegularPage.md")
+    _write(upstream, "kb/CONTRACT.md", "stack kb contract v2\n")
+    _write(upstream, "kb/CONVENTIONS.md.template", "template v2\n")
+    _git(upstream, "rm", "-q", "raw/CONTRACT.md")
+    _commit(upstream, "one upstream commit: edit + add + delete + contract + template + contract-delete")
+
+    _merge()
+
+    assert not (repo / "kb/ToDelete.md").exists()
+    assert not (repo / "kb/BrandNewPage.md").exists()
+    assert (repo / "kb/RegularPage.md").exists()
+    assert (repo / "kb/CONTRACT.md").read_text(encoding="utf-8") == "stack kb contract v2\n"
+    assert (repo / "kb/CONVENTIONS.md.template").read_text(encoding="utf-8") == "template v2\n"
+    assert (repo / "kb/CONVENTIONS.md").read_text(encoding="utf-8") == "instance conventions v1\n"
+    assert not (repo / "raw/CONTRACT.md").exists()
+
+
+def test_real_conflict_in_tools_leaves_the_merge_open(two_repos):
+    upstream, repo = two_repos
+
+    _write(repo, "tools/wikitool.py", "line one\nLOCAL CHANGE\nline three\n")
+    _commit(repo, "local edits tools/wikitool.py")
+    before = _git(repo, "rev-parse", "HEAD").stdout.strip()
+
+    _write(upstream, "tools/wikitool.py", "line one\nUPSTREAM CHANGE\nline three\n")
+    _commit(upstream, "upstream edits the same line")
+
+    with pytest.raises(typer.Exit) as excinfo:
+        _merge()
+    assert excinfo.value.exit_code == 1
+
+    assert _git(repo, "rev-parse", "HEAD").stdout.strip() == before
+    assert (repo / ".git" / "MERGE_HEAD").exists()
+
+
+def test_a_merge_git_refuses_to_open_deletes_nothing(two_repos, tmp_path):
+    """The failure mode with the worst blast radius if it is not guarded:
+    without MERGE_HEAD, every stack-owned path in HEAD reads as "the upstream
+    deleted it", and the restore loop would remove kb/CONTRACT.md,
+    raw/CONTRACT.md and every template. A merge git refuses to start must stop
+    before that, with the tree untouched."""
+    upstream, repo = two_repos
+    unrelated = tmp_path / "unrelated"
+    unrelated.mkdir()
+    _git(unrelated, "init", "-b", "main")
+    _git(unrelated, "config", "user.name", "Unrelated")
+    _git(unrelated, "config", "user.email", "unrelated@example.com")
+    _write(unrelated, "somefile.md", "no shared history with the instance\n")
+    _commit(unrelated, "unrelated root commit")
+
+    _git(repo, "remote", "set-url", "upstream", str(unrelated))
+    before = _git(repo, "rev-parse", "HEAD").stdout.strip()
+
+    with pytest.raises(typer.Exit) as excinfo:
+        _merge()
+    assert excinfo.value.exit_code == 1
+
+    assert _git(repo, "rev-parse", "HEAD").stdout.strip() == before
+    assert (repo / "kb/CONTRACT.md").read_text(encoding="utf-8") == "stack kb contract v1\n"
+    assert (repo / "raw/CONTRACT.md").exists()
+    assert (repo / "kb/CONVENTIONS.md.template").exists()
+    assert _git(repo, "status", "--porcelain").stdout == ""
+
+
+def test_success_message_reports_what_changed_not_what_was_restored(two_repos, capsys):
+    """Restoring every stack-owned path from MERGE_HEAD touches all of them
+    whether or not the upstream moved any, so the report has to ask git what
+    changed - otherwise a one-file update is announced as five."""
+    upstream, repo = two_repos
+    _write(upstream, "kb/CONTRACT.md", "stack kb contract v2\n")
+    _commit(upstream, "upstream changes exactly one stack path")
+
+    _merge()
+
+    out = capsys.readouterr().out
+    assert "Stack paths changed (1)" in out
+    assert "kb/CONTRACT.md" in out
+    assert "kb/CONVENTIONS.md.template" not in out
+
+
+def test_dirty_working_tree_is_refused_untouched(two_repos):
+    upstream, repo = two_repos
+    before = _git(repo, "rev-parse", "HEAD").stdout.strip()
+    (repo / "kb/CONTRACT.md").write_text("uncommitted local edit\n", encoding="utf-8")
+
+    _write(upstream, "kb/CONTRACT.md", "stack kb contract v2\n")
+    _commit(upstream, "upstream changes kb/CONTRACT.md")
+
+    with pytest.raises(typer.Exit) as excinfo:
+        _merge()
+    assert excinfo.value.exit_code == 1
+
+    assert _git(repo, "rev-parse", "HEAD").stdout.strip() == before
+    assert (repo / "kb/CONTRACT.md").read_text(encoding="utf-8") == "uncommitted local edit\n"
+
+
+def test_already_up_to_date_is_a_noop(two_repos):
+    upstream, repo = two_repos
+    before = _git(repo, "rev-parse", "HEAD").stdout.strip()
+
+    _merge()  # nothing new upstream at all
+
+    assert _git(repo, "rev-parse", "HEAD").stdout.strip() == before
+
+
+def test_merge_warns_when_the_publish_remote_gate_is_unarmed(two_repos, capsys):
+    upstream, repo = two_repos
+    assert git_publish.read_allowed_push_urls() is None  # no .wikitool-remotes.json in this repo
+
+    _write(upstream, "kb/CONTRACT.md", "stack kb contract v2\n")
+    _commit(upstream, "upstream changes kb/CONTRACT.md")
+
+    _merge()
+
+    captured = capsys.readouterr()
+    assert "WARN" in captured.out
+    assert ".wikitool-remotes.json" in captured.out
+
+
+def test_merge_stays_silent_when_the_publish_remote_gate_is_armed(two_repos, capsys):
+    upstream, repo = two_repos
+    (repo / config.PUBLISH_REMOTES_FILENAME).write_text(
+        '{"schema": 1, "allowed_push_urls": ["ssh://example/test.git"]}\n', encoding="utf-8"
+    )
+
+    _write(upstream, "kb/CONTRACT.md", "stack kb contract v2\n")
+    _commit(upstream, "upstream changes kb/CONTRACT.md")
+
+    _merge()
+
+    captured = capsys.readouterr()
+    assert "WARN" not in captured.out
+
+
+def test_dist_cmd_contract_only_stages_agree_with_ownership(two_repos):
+    """Consistency guard for the ownership refactor: `dist_cmd`'s own list of
+    stage-contract paths and `ownership.is_stack_owned` must not be able to
+    name a different set of stages - both are sourced from
+    `ownership.CONTENT_STAGES` now, so a stage added to one and not the other
+    fails this rather than only surfacing in a real merge."""
+    from chemenu.commands import dist_cmd
+
+    assert dist_cmd.CONTRACT_ONLY_STAGES  # sanity: the derivation still yields entries
+    for relative in dist_cmd.CONTRACT_ONLY_STAGES:
+        assert ownership.is_stack_owned(relative)
+
+
+# --- upstream verify --------------------------------------------------------
+
+
+def test_verify_is_clean_on_a_stack_owned_only_change(two_repos):
+    upstream, repo = two_repos
+    since = _git(repo, "rev-parse", "HEAD").stdout.strip()
+
+    _write(repo, "kb/CONTRACT.md", "stack kb contract v2\n")
+    _commit(repo, "advance kb/CONTRACT.md")
+
+    upstream_cmd.verify_command(since=since, until="HEAD")  # must not raise
+
+
+def test_verify_fails_on_a_hand_botched_merge(two_repos, capsys):
+    upstream, repo = two_repos
+    since = _git(repo, "rev-parse", "HEAD").stdout.strip()
+
+    _write(repo, "kb/SneakedIn.md", "content that arrived outside a stack-owned path\n")
+    _commit(repo, "a hand-resolved merge that let content through")
+
+    with pytest.raises(typer.Exit) as excinfo:
+        upstream_cmd.verify_command(since=since, until="HEAD")
+    assert excinfo.value.exit_code == 1
+
+    captured = capsys.readouterr()
+    assert "kb/SneakedIn.md" in captured.out
+
+
+# --- ownership predicate, exercised directly ---------------------------------
+
+
+@pytest.mark.parametrize(
+    "relative,expected",
+    [
+        ("kb/CONTRACT.md", True),
+        ("raw/CONTRACT.md", True),
+        ("work/CONTRACT.md", True),
+        ("reports/CONTRACT.md", True),
+        ("kb/CONVENTIONS.md.template", True),
+        ("kb/entities/COLLECTION.md.template", True),
+        ("kb/GLOSSARY.md.template", True),
+        ("kb/CONVENTIONS.md", False),
+        ("kb/entities/COLLECTION.md", False),
+        ("kb/concepts/Some Page.md", False),
+        ("raw/notes/x.md", False),
+        ("tools/CONTRACT.md", False),  # not a content stage
+        ("kb/log.md", False),  # export stub, not stack-owned
+    ],
+)
+def test_is_stack_owned(relative, expected):
+    assert ownership.is_stack_owned(relative) == expected