diff --git a/tools/agent-guard/src/agent_guard/__init__.py b/tools/agent-guard/src/agent_guard/__init__.py
index 3f28dfb18..6cb62e0aa 100644
--- a/tools/agent-guard/src/agent_guard/__init__.py
+++ b/tools/agent-guard/src/agent_guard/__init__.py
@@ -113,8 +113,8 @@ class Segment:
     """One simple command from a (possibly compound) shell line.
 
     ``argv`` has leading ``NAME=value`` env assignments stripped into ``env``;
-    ``raw`` is the original text of the segment (used for substring scans that
-    survive heredocs, e.g. the Co-Authored-By trailer).
+    ``raw`` is a reconstruction of this segment's own tokens only (used for
+    substring scans that survive heredocs, e.g. the Co-Authored-By trailer).
     """
 
     def __init__(self, tokens: list[str], raw: str) -> None:
@@ -164,12 +164,12 @@ def split_segments(command: str) -> list[Segment]:
     for tok in tokens:
         if tok in SHELL_OPERATORS:
             if current:
-                segments.append(Segment(current, command))
+                segments.append(Segment(current, shlex.join(current)))
                 current = []
         else:
             current.append(tok)
     if current:
-        segments.append(Segment(current, command))
+        segments.append(Segment(current, shlex.join(current)))
     return segments
 
 
diff --git a/tools/agent-guard/tests/test_guards.py b/tools/agent-guard/tests/test_guards.py
index cb864a7ec..9ac485ebb 100644
--- a/tools/agent-guard/tests/test_guards.py
+++ b/tools/agent-guard/tests/test_guards.py
@@ -218,6 +218,13 @@ def test_compound_command_guarded():
     assert dispatch('cd /tmp && git commit -m "x\nCo-Authored-By: a"') is not None
 
 
+def test_compound_command_other_segment_not_denied():
+    # The phrase lives in an unrelated earlier segment, not in the commit's
+    # own message, so the commit segment must not inherit it.
+    command = 'echo "note: never add a Co-Authored-By: trailer" && git commit -m "clean fix"'
+    assert dispatch(command) is None
+
+
 def test_malformed_command_allows():
     assert dispatch('gh pr comment 5 --body "oops') is None