R-469: lift the MariaDB half of the engine-major rule; add R-450's own-edge clause

Slice 4 shipped 2026-09-13, so the rule's own expiry condition is met — for MariaDB.
PostgreSQL and MySQL stay refused (R-463: no pg_upgrade, refuses to start on an
older major's datadir across eleven templates).

A MariaDB major is now allowed ONLY as its own edge: never in the same commit as
another image move in that template (R-450, the bookstack 0b73e5e shape).

Two new decoy cases; two red-proofs, each seen to fail. 40 cases green.
No template moved.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

scripts/check-engine-major.py

@@ -8,11 +8,15 @@ Run from the repo root:
 Exit 0 no engine crosses a major · 1 REFUSED · 2 INCONCLUSIVE (no parent to diff against, or a pin
 whose major cannot be read).
 
-THE RULE THIS ENFORCES (app-catalog `CLAUDE.md`, operator ruling 2026-09-13):
+THE RULE THIS ENFORCES (app-catalog `CLAUDE.md`, operator ruling 2026-09-13, AMENDED 2026-09-21):
 
-    Until the Update button takes a VERIFIED BACKUP as its precondition (update arc Slice 4,
-    felhom.eu OPEN-ITEMS.md R-448), no template may move a database-engine image across a major
-    version.
+    A MariaDB image may cross a MAJOR version, but ONLY AS ITS OWN EDGE — never in the same commit
+    as any other image move in that template. PostgreSQL and MySQL may NOT cross a major at all.
+
+The MariaDB half was lifted by R-469 when Slice 4 shipped; the second clause is R-450's second half,
+recorded while it was cheap: bookstack's `0b73e5e` moved the application 25.02.2 -> 26.05.2 AND
+MariaDB 11.6 -> 12.3 in one commit — TWO migrations behind one edge, and an unreadable failure when
+it breaks. One edge, one migration, so a failure names its own cause.
 
 WHY IT EXISTS. On 2026-09-13 every `mariadb:` sidecar gained `MARIADB_AUTO_UPGRADE=1`, so the day a
 MariaDB pin moves a major, the engine will CONVERT the customer's datadir on the next deliberate
@@ -54,6 +58,21 @@ import sys
 # Repository basenames that are database engines. A match here means "judge this service's major".
 ENGINES = ("mariadb", "mysql", "postgres", "postgresql")
 
+# R-469, 2026-09-21 — THE MARIADB HALF OF THE RULE IS LIFTED; THE POSTGRESQL HALF IS NOT.
+#
+# The rule's own condition was "until the Update button takes a verified backup as its precondition".
+# Slice 4 SHIPPED on 2026-09-13 (controller v0.237.0/v0.238.0, any tier since v0.239.0), so the
+# condition is met — for MariaDB. Every `mariadb:` sidecar carries MARIADB_AUTO_UPGRADE=1 (R-459) and
+# the harness has WATCHED the conversion run on the E3/E3b edges, with the seeded data read back
+# after. So a MariaDB major now has both halves it needs: a backup in front of it, and an engine that
+# performs the conversion.
+#
+# PostgreSQL has neither the second half nor a procedure: its image performs no `pg_upgrade` and
+# REFUSES to start on an older major's datadir, across ELEVEN templates (R-463). MySQL is in the same
+# position with nothing measured at all. Both stay refused until R-463 produces a scripted
+# `pg_upgrade` edge proven on all eleven.
+LIFTED = ("mariadb",)
+
 SERVICE_RE = re.compile(r"^  ([A-Za-z0-9_-]+):\s*$")
 IMAGE_RE = re.compile(r"^\s+image:\s*[\"']?(\S+?)[\"']?\s*$")
 TEMPLATE_RE = re.compile(r"^templates/[^/]+/docker-compose\.ya?ml$")
@@ -146,7 +165,7 @@ def main(argv):
         return 2
     files = [n for n in names.split("\n") if TEMPLATE_RE.match(n)]
 
-    compared, refused, unparseable = 0, [], []
+    compared, refused, bundled, allowed, unparseable = 0, [], [], [], []
     for path in files:
         rc_b, before_text, _ = git("show", "%s:%s" % (a, path))
         rc_a, after_text, _ = git("show", "%s:%s" % (b, path))
@@ -154,6 +173,11 @@ def main(argv):
             continue  # deleted at B: nothing is being offered
         before = images_in(before_text) if rc_b == 0 else {}
         after = images_in(after_text)
+
+        # EVERY image move in this template, engine or not. It is the input to the "own edge" rule
+        # (R-450): a MariaDB major is allowed only when it is the ONLY image this commit moves here.
+        moves = [svc for svc, img in after.items() if svc in before and before[svc] != img]
+
         for svc, img_after in after.items():
             eng_after = engine_of(img_after)
             if eng_after is None or svc not in before:
@@ -168,25 +192,42 @@ def main(argv):
             if mb is None or ma is None:
                 unparseable.append("%s %s: %s -> %s" % (path, svc, before[svc], img_after))
                 continue
-            if mb != ma:
-                refused.append((path, svc, eng_after[0], mb, ma, before[svc], img_after))
+            if mb == ma:
+                continue
+            row = (path, svc, eng_after[0], mb, ma, before[svc], img_after)
+            if eng_after[0] not in LIFTED:
+                refused.append(row)
+                continue
+            # R-469 + R-450: lifted, but it must be the ONLY image this commit moves in this
+            # template. `others` is named so the refusal can say WHAT it was bundled with.
+            others = [o for o in moves if o != svc]
+            if others:
+                bundled.append(row + (sorted(others),))
+                continue
+            allowed.append(row)
 
     print("engine-major gate — range %s..%s: %d compose file(s) changed, %d engine pin(s) compared"
           % (a, b, len(files), compared))
 
-    if refused:
+    if refused or bundled:
         print("")
         for path, svc, eng, mb, ma, ib, ia in refused:
             print("ENGINE-MAJOR GATE FAILED: %s service %s moves %s %d -> %d (%s -> %s)."
                   % (path, svc, eng, mb, ma, ib, ia))
-        print("RULE (app-catalog CLAUDE.md, operator ruling 2026-09-13): until the Update button takes "
-              "a VERIFIED BACKUP as its precondition (Slice 4, felhom.eu OPEN-ITEMS.md R-448), no "
-              "template may move a database-engine image across a MAJOR version.")
-        print("WHY: MariaDB sidecars now carry MARIADB_AUTO_UPGRADE=1 and WILL convert the customer's "
-              "datadir on the next Update; PostgreSQL's image refuses to start on an older major's "
-              "datadir (R-463). Either way this is a customer-data event with no backup in front of it.")
-        print("EXPIRY: this rule is removed DELIBERATELY when R-448 ships — the removal is its own "
-              "register row, not a silent edit. Until then, keep the engine within its major.")
+            print("  WHY: %s performs no datadir conversion of its own and REFUSES to start on an "
+                  "older major's datadir (R-463, eleven templates). The Update takes a backup first "
+                  "since Slice 4, but a backup is a route BACK, not a conversion — the app would "
+                  "simply not come up. This half of the rule stands until R-463 has a scripted "
+                  "pg_upgrade edge PROVEN on all eleven." % eng)
+        for path, svc, eng, mb, ma, ib, ia, others in bundled:
+            print("ENGINE-MAJOR GATE FAILED: %s service %s moves %s %d -> %d (%s -> %s) IN THE SAME "
+                  "COMMIT as %s." % (path, svc, eng, mb, ma, ib, ia, ", ".join(others)))
+            print("  WHY: an engine major gets its OWN EDGE (R-450). bookstack's 0b73e5e moved the "
+                  "application AND MariaDB 11.6 -> 12.3 in one commit: two migrations behind one "
+                  "edge, and an unreadable failure when it breaks. Split it into two commits — the "
+                  "engine alone, then the app.")
+        print("RULE (app-catalog CLAUDE.md, ruling 2026-09-13, amended by R-469 on 2026-09-21): "
+              "MariaDB may cross a major AS ITS OWN EDGE; PostgreSQL and MySQL may not cross one at all.")
         return 1
 
     if unparseable:
@@ -197,8 +238,12 @@ def main(argv):
               "forbids floating tags — pin a numbered tag.")
         return 2
 
-    print("engine-major gate OK — no database engine crosses a major version"
-          " (rule: CLAUDE.md, until Slice 4 / R-448 ships)")
+    for path, svc, eng, mb, ma, ib, ia in allowed:
+        print("engine-major gate ALLOWED: %s service %s moves %s %d -> %d (%s -> %s) as its own edge "
+              "— permitted since R-469 (Slice 4 shipped; MARIADB_AUTO_UPGRADE=1 converts the datadir)."
+              % (path, svc, eng, mb, ma, ib, ia))
+    print("engine-major gate OK — no forbidden engine major, and no engine major bundled with "
+          "another image move (rule: CLAUDE.md, amended by R-469 2026-09-21)")
     return 0