Refuse voice flips that would strand openers or preverbal adverbs.

Leftovers from active_to_passive land after the agent, which silently moved fronted phrases and words like "also" / "carefully" into the wrong place. Hyphenated compounds (high-quality) are kept intact.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/engine/voice/__init__.py

@@ -28,6 +28,17 @@ def _ranges_text(doc, indices: set[int]) -> str:
     return " ".join(part for part in parts if part)
 
 
+def _is_structural_punct(token, doc) -> bool:
+    """Punctuation that separates phrases, as opposed to joining a compound.
+
+    The hyphens in "high-quality" and "word-of-mouth" are ``punct`` too;
+    dropping them would rebuild the sentence as "high quality".
+    """
+    if token.dep_ != "punct":
+        return False
+    return bool(token.whitespace_) or token.i == len(doc) - 1
+
+
 def _continue_case(text: str, head) -> str:
     value = text.strip()
     if not value or head.pos_ == "PROPN":
@@ -221,7 +232,7 @@ def active_to_passive(text: str) -> str | None:
         | {root.i}
         | {token.i for token in auxiliaries}
         | {token.i for token in negations}
-        | {token.i for token in doc if token.dep_ == "punct"}
+        | {token.i for token in doc if _is_structural_punct(token, doc)}
     )
     extras = {
         token.i
@@ -229,6 +240,19 @@ def active_to_passive(text: str) -> str | None:
         if token.i not in consumed
     }
 
+    # Leftovers are appended after the agent, which only reads correctly for
+    # trailing modifiers. Anything that opened the sentence ("By delivering
+    # good service, organizations can …") or sat before the verb ("also")
+    # would land in the wrong place and change what it modifies.
+    if extras:
+        subject_start = min(subject_indices)
+        if any(index < subject_start for index in extras):
+            return None
+        if any(
+            doc[index].pos_ in {"ADV", "PART"} and index < root.i for index in extras
+        ):
+            return None
+
     new_subject = _start_case(_ranges_text(doc, object_indices))
     agent = _continue_case(_ranges_text(doc, subject_indices), subject)
     complement = _ranges_text(doc, complement_indices)

tests/test_structural_variation.py

@@ -37,6 +37,27 @@ def test_passive_to_active_skips_negation_needing_do_support():
     assert passive_to_active("Mistakes were not corrected by the editor.") is None
 
 
+def test_active_to_passive_refuses_to_relocate_a_fronted_phrase():
+    """Leftovers land after the agent, which would strip the opener's scope."""
+    text = (
+        "By consistently delivering high-quality service, organizations can "
+        "establish a strong reputation."
+    )
+    assert active_to_passive(text) is None
+
+
+def test_active_to_passive_refuses_to_strand_a_preverbal_adverb():
+    assert active_to_passive(
+        "Organizations can also encourage positive recommendations."
+    ) is None
+    assert active_to_passive("Maria carefully submitted the final report.") is None
+
+
+def test_active_to_passive_keeps_hyphenated_compounds_intact():
+    result = active_to_passive("The team published the high-quality version last week.")
+    assert result == "The high-quality version was published by the team last week."
+
+
 def test_active_and_passive_are_not_mutually_reachable():
     text = "Readers reviewed the report yesterday."
     passive = active_to_passive(text)