From 40ed284b7a47bff91bf97a85e081d57604ebe645 Mon Sep 17 00:00:00 2001
From: ispyisail <shane@ringrose.co.nz>
Date: Mon, 28 Sep 2026 11:12:25 +1300
Subject: [PATCH] qet-mcp: qet_diff no longer reports untouched elements as
 changed

QElectroTech writes an empty label as an empty <elementInformation> and
drops it on the next save. qet_diff compared the raw information bags, so
re-saving grafcet.qet with no edit reported 9 of its 37 elements as
info_changed ({"label": ""} -> {}), and Projet_vierge.qet 4.

An empty field and a missing one now compare equal, and info_changed lists
only fields that hold a value. The resave test now also requires an empty
info_changed; it failed on grafcet.qet and Projet_vierge.qet before this
change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 misc/qet-mcp/qet_mcp.py      |  9 +++++++--
 misc/qet-mcp/test_qet_mcp.py | 21 +++++++++++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/misc/qet-mcp/qet_mcp.py b/misc/qet-mcp/qet_mcp.py
index fef21791c..69cdeb31f 100755
--- a/misc/qet-mcp/qet_mcp.py
+++ b/misc/qet-mcp/qet_mcp.py
@@ -492,9 +492,14 @@ def tool_diff(before: str, after: str) -> dict:
         if a["label"] != b["label"]:
             relabelled.append({"uuid": k, "name": a["name"],
                                "from": a["label"], "to": b["label"]})
-        if a["info"] != b["info"]:
+        # An empty field and a missing one mean the same thing, and
+        # QElectroTech drops empty ones when it saves, so compare only the
+        # fields that hold a value.
+        a_info = {n: v for n, v in a["info"].items() if v}
+        b_info = {n: v for n, v in b["info"].items() if v}
+        if a_info != b_info:
             changed_info.append({"uuid": k, "name": a["name"],
-                                 "from": a["info"], "to": b["info"]})
+                                 "from": a_info, "to": b_info})
 
     a_co = {r["key"]: r for i, c, ix in _conductors(_root(before))
             for r in [_conductor_row(i, c, ix)]}
diff --git a/misc/qet-mcp/test_qet_mcp.py b/misc/qet-mcp/test_qet_mcp.py
index b874a3356..4bf31e6cb 100644
--- a/misc/qet-mcp/test_qet_mcp.py
+++ b/misc/qet-mcp/test_qet_mcp.py
@@ -777,6 +777,26 @@ class Diff(unittest.TestCase):
         b = self.project("b.qet", version="0.200.1-dev")
         self.assertEqual(m.tool_diff(a, b)["folios"]["changed"], [])
 
+    def test_empty_information_and_a_missing_one_are_the_same(self):
+        """QElectroTech writes an empty label as <elementInformation name="label"/>
+        and drops it on the next save, so comparing the raw bags made every
+        unlabelled element of a re-saved project look edited."""
+        def proj(infos):
+            return (f'<project><diagram><elements><element uuid="{{e}}" type="x" x="0" y="0">'
+                    f'<elementInformations>{infos}</elementInformations>'
+                    f'</element></elements><conductors/></diagram></project>')
+        a = self.dir / "a.qet"
+        b = self.dir / "b.qet"
+        c = self.dir / "c.qet"
+        a.write_text(proj('<elementInformation show="1" name="label"></elementInformation>'
+                          '<elementInformation show="1" name="comment">  </elementInformation>'))
+        b.write_text(proj(''))
+        c.write_text(proj('<elementInformation show="1" name="label">K1</elementInformation>'))
+        self.assertEqual(m.tool_diff(str(a), str(b))["elements"]["info_changed"], [])
+        # A value that really appears or disappears is still reported.
+        changed = m.tool_diff(str(b), str(c))["elements"]["info_changed"]
+        self.assertEqual([(x["from"], x["to"]) for x in changed], [({}, {"label": "K1"})])
+
     def test_element_text_field_moves_and_restyles_are_reported(self):
         def proj(x, size, frame, extra=""):
             return (f'<project><diagram><elements><element uuid="{{e}}"><dynamic_texts>'
@@ -2747,6 +2767,7 @@ class CorpusIntegration(unittest.TestCase):
                     if "unstable_keys" not in c:
                         self.assertEqual((len(c["added"]), len(c["removed"])), (0, 0))
                     self.assertEqual(r["diff"]["elements"]["moved_count"], 0)
+                    self.assertEqual(r["diff"]["elements"]["info_changed"], [])
         finally:
             sb.close()