R-325 (felhom.eu half): hub_copy_gate accepts the controller gate importing the shared stem list

Once retrieval_promise_gate.py imports customer_copy_vocab and drops its STEMS literal, the drift
check reads "ok — single source" instead of failing on the missing literal. An import only in a
comment, or beside a stale literal, is still drift. Pinned by scripts/test_hub_copy_drift.py.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

scripts/hub_copy_gate.py

@@ -189,18 +189,31 @@ def scan_stems():
     return convictions, seen
 
 
-def check_drift():
+# R-325: the destination — the controller gate IMPORTS the shared list instead of carrying a literal.
+# Matched at the start of a line, so an import written only in a `#` comment does not count.
+_SHARED_IMPORT_RE = re.compile(
+    r"^(?:from\s+customer_copy_vocab\s+import\s+[^\n]*\bRETRIEVAL_STEMS\b|import\s+customer_copy_vocab\b)", re.M)
+
+
+def check_drift(sibling=None):
     """The controller gate's STEMS must equal the shared list. Returns (status, message).
 
     status: "ok" | "drift" | "inconclusive"
+
+    R-325: once the controller gate imports `customer_copy_vocab` and carries NO `STEMS` literal of its
+    own, the two cannot diverge and that is "ok". A literal, if present, is still compared — an import
+    beside a stale literal is drift. Pinned by scripts/test_hub_copy_drift.py.
     """
-    sibling = os.path.join(os.path.dirname(_REPO), "felhom-controller",
-                           "controller", "scripts", "retrieval_promise_gate.py")
+    if sibling is None:
+        sibling = os.path.join(os.path.dirname(_REPO), "felhom-controller",
+                               "controller", "scripts", "retrieval_promise_gate.py")
     if not os.path.exists(sibling):
         return "inconclusive", ("the felhom-controller clone is absent, so the shared stem list "
                                "could not be compared against the gate that also uses it (%s)" % sibling)
     text = open(sibling, encoding="utf-8").read()
     m = re.search(r"^STEMS\s*=\s*\[(.*?)\]", text, re.M | re.S)
+    if not m and _SHARED_IMPORT_RE.search(text):
+        return "ok", "controller gate imports the shared list (customer_copy_vocab.py) — single source"
     if not m:
         return "drift", "could not find a STEMS list in the controller gate — its shape changed"
     theirs = re.findall(r"[\"']([^\"']+)[\"']", m.group(1))

scripts/test_hub_copy_drift.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+"""R-325: hub_copy_gate.check_drift accepts the controller gate IMPORTING the shared stem list.
+
+Cases: a matching literal (ok), a diverged literal (drift), the import with no literal (ok — the
+destination), an import that exists only in a comment (drift — the label without the fact), an import
+beside a stale literal (drift), and an absent file (inconclusive, never a pass).
+Run: python3 scripts/test_hub_copy_drift.py
+"""
+import os
+import sys
+import tempfile
+
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+import hub_copy_gate as g  # noqa: E402
+from customer_copy_vocab import RETRIEVAL_STEMS  # noqa: E402
+
+lit = "STEMS = [%s]\n" % ", ".join('"%s"' % x for x in RETRIEVAL_STEMS)
+imp = "sys.path.insert(0, VOCAB_DIR)\nfrom customer_copy_vocab import RETRIEVAL_STEMS as STEMS  # noqa\n"
+CASES = [
+    ("matching-literal", "import re\n" + lit, "ok"),
+    ("diverged-literal", "import re\nSTEMS = [\"visszaallithat\"]\n", "drift"),
+    ("imports-shared", "import re\n" + imp, "ok"),
+    ("import-in-comment-only", "import re\n# from customer_copy_vocab import RETRIEVAL_STEMS\n", "drift"),
+    ("import-beside-stale-literal", imp + "STEMS = [\"x\"]\n", "drift"),
+]
+fails = 0
+tmp = tempfile.mkdtemp(prefix="r325-")
+for name, body, want in CASES:
+    p = os.path.join(tmp, name + ".py")
+    with open(p, "w", encoding="utf-8") as f:
+        f.write(body)
+    got, msg = g.check_drift(p)
+    ok = got == want
+    fails += not ok
+    print("  %s %-28s want %-12s got %s" % ("ok  " if ok else "FAIL", name, want, got))
+got, _ = g.check_drift(os.path.join(tmp, "absent.py"))
+if got != "inconclusive":
+    fails += 1
+    print("  FAIL absent file -> %s, want inconclusive" % got)
+else:
+    print("  ok   absent file                  want inconclusive got inconclusive")
+print("test_hub_copy_drift: %s" % ("FAILED" if fails else "OK"))
+sys.exit(1 if fails else 0)