fix(task-2): find_replace rewrites every surface of a multi-line attribute; COM explode propagates a failing read and undoes a failed burst

Headless text_find_replace matched and wrote only dxf.text of an ATTRIB/ATTDEF, so on a multi-line attribute it reported replaced: 1 while block_get_attributes and block_explode still carried the old embedded MTEXT (and a needle on the second line was never found). The ATTRIB/ATTDEF branch now reads through _attrib_value and writes through _write_attrib_value, the same pair block_get_attributes / block_set_attributes use.

COM block_explode swallowed a failing GetAttributes() (attrs = ()), GetConstantAttributes() and Invisible, then exploded, deleted every ATTDEF placeholder and the reference and returned ok: True with no attribute text -- every value destroyed silently on a transient RPC_E_CALL_REJECTED. Those reads now happen before Explode() and propagate with nothing written; a failure after the explode deletes the members it added and the TEXTs written so far and leaves the reference in place (_undo_explode), so the drawing is never left half-burst under an exception. The fakes gain the members a live AcadBlockReference / AcadAttributeDefinition always expose (GetConstantAttributes, Constant, Invisible) instead of relying on the swallow.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd

backends/com_backend.py

@@ -3431,13 +3431,16 @@ class ComBackend(AutoCADBackend):
         A multi-line attribute (``MTextAttribute`` true) keeps its content in
         ``MTextAttributeContent`` -- ``TextString`` is one flattened string --
         and its box width in ``MTextBoundaryWidth``; ``mtext`` marks it so the
-        writer builds an MTEXT. An object that does not expose the member is
+        writer builds an MTEXT. An object that does not expose *that* member
-        single-line.
+        is single-line (the member is younger than the ActiveX surface, and a
+        ``TextString`` fallback loses nothing).
+
+        ``Invisible`` is *not* guessed: a read failure used to default to
+        visible, so a hidden attribute's value (a link, a cost code) became
+        visible text with ``ok: True``. The failure propagates, and the
+        caller of this helper reads it before anything is written.
         """
-        try:
         invisible = bool(attr.Invisible)
-        except Exception:
-            invisible = False
         try:
             is_mtext = bool(attr.MTextAttribute)
         except Exception:
@@ -3547,6 +3550,21 @@ class ComBackend(AutoCADBackend):
             text.Visible = False
         return text
 
+    @staticmethod
+    def _undo_explode(exploded, texts) -> None:
+        """Delete what a failed burst has already written (best effort).
+
+        An object the burst deleted itself (an ATTDEF placeholder) raises on a
+        second ``Delete``; that is skipped, every other failure is logged and
+        the next object is tried, so the original exception -- the one the
+        caller is about to re-raise -- stays the one the caller sees.
+        """
+        for obj in tuple(texts) + tuple(exploded):
+            try:
+                obj.Delete()
+            except Exception as exc:
+                log.debug("explode rollback: %r not deleted: %s", obj, exc)
+
     @staticmethod
     def _is_constant_attdef(obj, constant_tags: set) -> bool:
         """Whether an exploded ``AcDbAttributeDefinition`` is a constant attribute.
@@ -3560,10 +3578,7 @@ class ComBackend(AutoCADBackend):
             return bool(obj.Constant)
         except Exception:
             pass
-        try:
         return str(obj.TagString) in constant_tags
-        except Exception:
-            return False
 
     async def block_explode(self, handle) -> dict:
         """Explode an INSERT through ActiveX; ATTRIB values survive as TEXT.
@@ -3618,6 +3633,16 @@ class ComBackend(AutoCADBackend):
         and an xref (``Blocks.Item(Name).IsXRef``; ActiveX ``Explode()`` raises
         on one, the headless engine used to delete it) -- the same three
         refusals the headless engine names.
+
+        No read that decides what gets written is guessed: ``GetAttributes()``,
+        ``GetConstantAttributes()`` and each attribute's ``Invisible`` are read
+        before ``Explode()`` and a failure propagates with nothing written
+        (a swallowed ``GetAttributes()`` used to burst *no* value and report
+        ``ok: True``). A failure after the explode -- a constant ATTDEF whose
+        members cannot be read, an ``AddText`` that is refused -- undoes what
+        the explode added and the TEXTs written so far and leaves the
+        reference in place (``_undo_explode``), so the drawing is never left
+        half-burst under an exception.
         """
 
         def _sync():
@@ -3645,21 +3670,23 @@ class ComBackend(AutoCADBackend):
                     "be exploded (bind it into the drawing first)"
                 )
             owner = _owner_layout_block(doc, ent, handle)
-            try:
+            # Every read that decides what the burst writes happens *before*
+            # ``Explode()`` and propagates: swallowing a failing
+            # ``GetAttributes()`` (a transient ``RPC_E_CALL_REJECTED`` while
+            # AutoCAD is busy is enough) went on to explode, delete every
+            # ATTDEF placeholder and the reference, and report ``ok: True``
+            # with ``attribute_texts: []`` -- every value destroyed silently,
+            # the defect this method exists to remove. Nothing has been
+            # written yet, so raising here costs nothing.
             attrs = ent.GetAttributes()
-            except Exception as exc:
-                log.debug("GetAttributes failed before explode: %s", exc)
-                attrs = ()
             captured = [self._capture_attrib(attr) for attr in attrs]
-            constant_tags: set = set()
+            constant_tags: set = {str(attr.TagString) for attr in ent.GetConstantAttributes() or ()}
-            try:
+            exploded = tuple(ent.Explode() or ())
-                for attr in ent.GetConstantAttributes() or ():
-                    constant_tags.add(str(attr.TagString))
-            except Exception as exc:
-                log.debug("GetConstantAttributes failed before explode: %s", exc)
-            exploded = ent.Explode()
             inserted = []
-            for obj in exploded or ():
+            attribute_texts = []
+            texts = []
+            try:
+                for obj in exploded:
                     if obj.ObjectName == "AcDbAttributeDefinition":
                         if self._is_constant_attdef(obj, constant_tags):
                             # A constant attribute's only text; already WCS here.
@@ -3667,10 +3694,17 @@ class ComBackend(AutoCADBackend):
                         obj.Delete()  # the tag placeholder EXPLODE leaves; the value is below
                         continue
                     inserted.append(str(obj.Handle))
-            attribute_texts = []
                 for item in captured:
                     text = self._add_text_from_capture(owner, item)
+                    texts.append(text)
                     attribute_texts.append(str(text.Handle))
+            except Exception:
+                # ActiveX ``Explode()`` leaves the reference in place, so the
+                # drawing is put back to exactly that: the members it added and
+                # the TEXTs written so far are removed, the reference stays,
+                # and the failure propagates instead of a half-burst symbol.
+                self._undo_explode(exploded, texts)
+                raise
             ent.Delete()
             _regen()
             return {

backends/ezdxf_backend.py

@@ -3958,13 +3958,27 @@ class EzdxfBackend(AutoCADBackend):
                 seen.add(key)
                 if layer and entity.dxf.get("layer", "0") != layer:
                     continue
-                current = entity.text if dxftype == "MTEXT" else entity.dxf.get("text", "")
+                # An ATTRIB/ATTDEF is read and written through the attribute
+                # helpers: a multi-line one keeps its content in an embedded
+                # MTEXT and ``dxf.text`` is only the first line, so matching
+                # and writing ``dxf.text`` alone reported ``replaced: 1`` while
+                # ``block_get_attributes`` and ``block_explode`` still carried
+                # the old value. One value, every surface -- the same rule
+                # ``block_set_attributes`` follows.
+                if dxftype == "MTEXT":
+                    current = entity.text
+                elif dxftype in ("ATTRIB", "ATTDEF"):
+                    current = self._attrib_value(entity)
+                else:
+                    current = entity.dxf.get("text", "")
                 if not current or not pattern.search(current):
                     continue
                 updated = pattern.sub(replace, current)
                 if not dry_run:
                     if dxftype == "MTEXT":
                         entity.text = updated
+                    elif dxftype in ("ATTRIB", "ATTDEF"):
+                        self._write_attrib_value(entity, updated)
                     else:
                         entity.dxf.text = updated
                 changed.append(

server.py

@@ -2417,7 +2417,9 @@ async def text_find_replace(
     never searched" are different answers. Block *definitions* are included, so
     the next insert does not reintroduce the old text. DIMENSION text is out of
     scope: its text field holds the `<>` override placeholder rather than the
-    measurement, so editing it would break the association.
+    measurement, so editing it would break the association. A multi-line
+    attribute is matched and rewritten as the whole value (`Line1\\PLine2`),
+    the same value `block_get_attributes` reports and `block_explode` bursts.
     """
     await ctx.info(f"Replacing {find!r} with {replace!r}{' (dry run)' if dry_run else ''}")
     return await _backend(ctx).text_find_replace(find, replace, layer or None, match_case, dry_run)

tests/test_track_a_hardening.py

@@ -328,7 +328,7 @@ async def test_explode_refuses_a_non_insert_without_writing(backend):
 
 async def test_com_explode_deletes_attdefs_adds_text_per_attrib_and_deletes_the_reference(com):
     backend, document, space = com
-    attdef = _FakeObject("AcDbAttributeDefinition", "D1")
+    attdef = _FakeObject("AcDbAttributeDefinition", "D1", Constant=False)
     line = _FakeObject("AcDbLine", "L1")
     visible = _FakeObject(
         "AcDbAttribute",
@@ -358,6 +358,7 @@ async def test_com_explode_deletes_attdefs_adds_text_per_attrib_and_deletes_the_
         Name="TB",
         OwnerID=1,
         GetAttributes=lambda: (visible, hidden),
+        GetConstantAttributes=lambda: (),
         Explode=lambda: (line, attdef),
     )
     document.objects["2F"] = ref
@@ -412,6 +413,7 @@ async def test_com_explode_adds_the_text_to_the_owner_block_not_the_active_layou
         Name="TB",
         OwnerID=2,
         GetAttributes=lambda: (title,),
+        GetConstantAttributes=lambda: (),
         Explode=lambda: (line,),
     )
     document.objects["4B"] = ref
@@ -439,6 +441,7 @@ async def test_com_explode_refuses_a_nested_reference_before_explode(com):
         Name="TB",
         OwnerID=3,
         GetAttributes=lambda: (),
+        GetConstantAttributes=lambda: (),
         Explode=_explode,
     )
     document.objects["5C"] = ref
@@ -482,6 +485,7 @@ async def test_com_explode_carries_the_attrib_frame_and_style_onto_the_text(com)
         Name="TB",
         OwnerID=1,
         GetAttributes=lambda: (attrib,),
+        GetConstantAttributes=lambda: (),
         Explode=lambda: (),
     )
     document.objects["6D"] = ref
@@ -555,6 +559,7 @@ async def test_com_explode_skips_frame_members_the_attrib_does_not_expose(com):
         Name="TB",
         OwnerID=1,
         GetAttributes=lambda: (attrib,),
+        GetConstantAttributes=lambda: (),
         Explode=lambda: (),
     )
     document.objects["7E"] = ref
@@ -647,6 +652,7 @@ async def test_com_explode_falls_back_to_the_constant_tag_list_when_constant_is_
         Height=2.0,
         Rotation=0.0,
         Layer="0",
+        Invisible=False,
     )
     placeholder = _FakeObject("AcDbAttributeDefinition", "D1", TagString="TAG")
     ref = _FakeObject(
@@ -973,6 +979,7 @@ async def test_com_explode_turns_a_multi_line_attrib_into_mtext(com):
         Name="TB",
         OwnerID=1,
         GetAttributes=lambda: (note, plain),
+        GetConstantAttributes=lambda: (),
         Explode=lambda: (line,),
     )
     document.objects["6D"] = ref
@@ -1028,6 +1035,7 @@ async def test_com_explode_multi_line_attrib_takes_the_frame_before_the_angle(co
         Name="TB",
         OwnerID=1,
         GetAttributes=lambda: (note,),
+        GetConstantAttributes=lambda: (),
         Explode=lambda: (),
     )
     document.objects["7E"] = ref
@@ -1071,6 +1079,7 @@ async def test_com_explode_refuses_an_xref_before_explode(com):
         Name="XREF_DETAIL",
         OwnerID=1,
         GetAttributes=lambda: (),
+        GetConstantAttributes=lambda: (),
         Explode=_explode,
     )
     document.objects["8A"] = ref
@@ -1097,6 +1106,7 @@ async def test_com_explode_refuses_a_minsert_by_name_before_explode(com):
         Rows=2,
         Columns=3,
         GetAttributes=lambda: (),
+        GetConstantAttributes=lambda: (),
         Explode=_explode,
     )
     document.objects["9B"] = grid
@@ -1286,3 +1296,211 @@ async def test_explode_opaque_members_is_declared_on_both_engines():
     headless = EzdxfBackend().capabilities().features["explode_opaque_members"]
     assert headless.supported is False and "OLE2FRAME" in (headless.reason or "")
     assert ComBackend().capabilities().features["explode_opaque_members"].supported is True
+
+
+# ── Task 2 (review 3): find_replace on a multi-line attribute; COM reads propagate ─
+
+
+async def test_find_replace_rewrites_every_surface_of_a_multi_line_attrib(backend):
+    """``text_find_replace`` matched and wrote only ``dxf.text`` of an ATTRIB,
+    so on a multi-line attribute it reported ``replaced: 1, 'OLD ONE' ->
+    'NEW ONE'`` while ``block_get_attributes`` still read ``OLD ONE\\POLD TWO``
+    and ``block_explode`` burst it. The ATTRIB branch goes through the same
+    reader and writer the attribute tools use: one value, every surface."""
+    ref, attrib = await _insert_multi_line(backend)
+
+    result = await backend.text_find_replace("OLD", "NEW")
+
+    assert result["replaced"] == 1
+    (entry,) = result["entities"]
+    assert entry["type"] == "ATTRIB"
+    assert entry["before"] == "OLD ONE\\POLD TWO", "the whole value is what was matched"
+    assert entry["after"] == "NEW ONE\\PNEW TWO", "every line is replaced, not the first"
+    assert attrib.has_embedded_mtext_entity, "still a multi-line attribute"
+    assert attrib.virtual_mtext_entity().text == "NEW ONE\\PNEW TWO"
+    assert attrib.dxf.text == "NEW ONE\\PNEW TWO"
+    assert await backend.block_get_attributes(ref.handle) == {"NOTE": "NEW ONE\\PNEW TWO"}
+    exploded = await backend.block_explode(ref.handle)
+    (handle,) = exploded["attribute_texts"]
+    raw = backend._doc.entitydb[handle]
+    assert raw.dxftype() == "MTEXT" and raw.text == "NEW ONE\\PNEW TWO"
+    assert backend._doc.audit().errors == []
+
+
+async def test_find_replace_matches_a_line_below_the_first_of_a_multi_line_attrib(backend):
+    """A needle that only occurs on the second line was invisible to a search
+    of ``dxf.text`` (the first line alone): ``replaced: 0`` on a value the
+    reader plainly reports."""
+    ref, attrib = await _insert_multi_line(backend)
+
+    result = await backend.text_find_replace("TWO", "2")
+
+    assert result["replaced"] == 1
+    assert await backend.block_get_attributes(ref.handle) == {"NOTE": "OLD ONE\\POLD 2"}
+    assert attrib.virtual_mtext_entity().text == "OLD ONE\\POLD 2"
+
+
+async def test_find_replace_dry_run_reports_the_whole_multi_line_value_and_writes_nothing(
+    backend,
+):
+    ref, attrib = await _insert_multi_line(backend)
+
+    result = await backend.text_find_replace("OLD", "NEW", dry_run=True)
+
+    assert result["dry_run"] is True and result["replaced"] == 1
+    assert result["entities"][0]["before"] == "OLD ONE\\POLD TWO"
+    assert result["entities"][0]["after"] == "NEW ONE\\PNEW TWO"
+    assert attrib.virtual_mtext_entity().text == "OLD ONE\\POLD TWO"
+    assert attrib.dxf.text == "OLD ONE"
+    assert await backend.block_get_attributes(ref.handle) == {"NOTE": "OLD ONE\\POLD TWO"}
+
+
+async def test_find_replace_rewrites_a_multi_line_attdef_inside_a_block_definition(backend):
+    """The ATTDEF twin: the default a new INSERT is prompted with lives in the
+    block definition, and a multi-line one keeps it in an embedded MTEXT."""
+    blk = backend._doc.blocks.new(name="MLD")
+    blk.add_line((0, 0), (10, 0))
+    attdef = blk.add_attdef("NOTE", insert=(0, 3), text="x", dxfattribs={"height": 2.5})
+    _embed_multi_line(attdef, ["OLD ONE", "OLD TWO"], (0, 3))
+
+    result = await backend.text_find_replace("OLD", "NEW")
+
+    assert result["replaced"] == 1 and result["entities"][0]["type"] == "ATTDEF"
+    assert result["entities"][0]["after"] == "NEW ONE\\PNEW TWO"
+    assert attdef.has_embedded_mtext_entity
+    assert attdef.virtual_mtext_entity().text == "NEW ONE\\PNEW TWO"
+    assert attdef.dxf.text == "NEW ONE\\PNEW TWO"
+    assert backend._doc.audit().errors == []
+
+
+async def test_find_replace_leaves_a_single_line_attrib_single_line(backend):
+    _define_tagged_block(backend, "TB3")
+    ref = await backend.block_insert("TB3", 0, 0, attributes={"TAG": "OLD-1"})
+    attrib = backend._doc.entitydb[ref.handle].attribs[0]
+
+    result = await backend.text_find_replace("OLD", "NEW")
+
+    assert result["replaced"] == 1 and result["entities"][0]["after"] == "NEW-1"
+    assert attrib.dxf.text == "NEW-1" and not attrib.has_embedded_mtext_entity
+    assert await backend.block_get_attributes(ref.handle) == {"TAG": "NEW-1"}
+
+
+def _boom(*_args):
+    raise RuntimeError("RPC_E_CALL_REJECTED: the application is busy")
+
+
+@pytest.mark.parametrize(
+    "broken",
+    ["GetAttributes", "GetConstantAttributes", "Invisible"],
+    ids=["get_attributes", "get_constant_attributes", "invisible"],
+)
+async def test_com_explode_propagates_a_failing_read_before_explode(com, broken):
+    """A failing ``GetAttributes()`` used to be swallowed (``attrs = ()``), and
+    the burst went on to explode, delete every ATTDEF placeholder and the
+    reference, and return ``ok: True, attribute_texts: []`` -- every value
+    destroyed silently, the defect the BURST rule exists to remove. A
+    transient ``RPC_E_CALL_REJECTED`` while AutoCAD is busy is enough to
+    trigger it. The same for ``GetConstantAttributes()`` (a constant ATTDEF
+    would then be deleted as a placeholder) and for ``Invisible`` (a hidden
+    value would appear as visible text). Nothing has been written at that
+    point, so the failure propagates and the drawing is untouched."""
+    backend, document, space = com
+    dispatched = []
+    attdef = _FakeObject("AcDbAttributeDefinition", "D1", Constant=False)
+    line = _FakeObject("AcDbLine", "L1")
+
+    def _explode():
+        dispatched.append("Explode")
+        return (line, attdef)
+
+    attrib_members = dict(
+        TagString="TAG",
+        TextString="P-101",
+        InsertionPoint=(7.0, 15.2, 0.0),
+        Height=5.0,
+        Rotation=0.0,
+        Layer="PID-TAG",
+        Invisible=True,
+    )
+    if broken == "Invisible":
+        attrib_members.pop("Invisible")  # the read raises AttributeError on the fake
+    attrib = _FakeObject("AcDbAttribute", "A1", **attrib_members)
+    ref_members = dict(
+        Name="TB",
+        OwnerID=1,
+        GetAttributes=lambda: (attrib,),
+        GetConstantAttributes=lambda: (),
+        Explode=_explode,
+    )
+    if broken in ref_members:
+        ref_members[broken] = _boom
+    ref = _FakeObject("AcDbBlockReference", "2F", **ref_members)
+    document.objects["2F"] = ref
+
+    with pytest.raises((RuntimeError, AttributeError)):
+        await backend.block_explode("2F")
+
+    assert dispatched == [], "the read failed before Explode() was dispatched"
+    assert space.calls == [] and ref.deleted is False and attdef.deleted is False
+
+
+class _SpaceFailingSecondAddText(_FakeSpace):
+    def AddText(self, text, point, height):
+        if self.texts:
+            raise RuntimeError("E_FAIL: AddText")
+        return super().AddText(text, point, height)
+
+
+async def test_com_explode_undoes_a_burst_that_fails_after_explode(com):
+    """ActiveX ``Explode()`` leaves the reference in place, so a failure after
+    it (here ``AddText`` on the second attribute; a constant ATTDEF whose
+    members cannot be read is the other way in) is put back to that: the
+    members the explode added and the TEXTs written so far are deleted, the
+    reference stays, and the failure propagates rather than a half-burst
+    symbol with ``ok: True``."""
+    backend, document, space = com
+    sheet = _SpaceFailingSecondAddText(name="Sheet")
+    document.owners[2] = sheet
+    first = _FakeObject(
+        "AcDbAttribute",
+        "A1",
+        TagString="TAG",
+        TextString="P-101",
+        InsertionPoint=(7.0, 15.2, 0.0),
+        Height=5.0,
+        Rotation=0.0,
+        Layer="0",
+        Invisible=False,
+    )
+    second = _FakeObject(
+        "AcDbAttribute",
+        "A2",
+        TagString="LINK",
+        TextString="L-1",
+        InsertionPoint=(1.0, 1.0, 0.0),
+        Height=2.0,
+        Rotation=0.0,
+        Layer="0",
+        Invisible=False,
+    )
+    placeholder = _FakeObject("AcDbAttributeDefinition", "D1", Constant=False)
+    line = _FakeObject("AcDbLine", "L1")
+    ref = _FakeObject(
+        "AcDbBlockReference",
+        "4C",
+        Name="TB",
+        OwnerID=2,
+        GetAttributes=lambda: (first, second),
+        GetConstantAttributes=lambda: (),
+        Explode=lambda: (line, placeholder),
+    )
+    document.objects["4C"] = ref
+
+    with pytest.raises(RuntimeError, match="E_FAIL: AddText"):
+        await backend.block_explode("4C")
+
+    assert ref.deleted is False, "the reference Explode() left in place is kept"
+    assert line.deleted is True, "the member Explode() added is removed"
+    assert placeholder.deleted is True
+    assert [t.deleted for t in sheet.texts] == [True], "the TEXT written before the failure"
+    assert space.calls == []