diff --git a/engine/hooks/pr-schema-gate/README.md b/engine/hooks/pr-schema-gate/README.md
index 958caa21..917778ac 100644
--- a/engine/hooks/pr-schema-gate/README.md
+++ b/engine/hooks/pr-schema-gate/README.md
@@ -82,7 +82,9 @@ push` and moved on without running `create-pr.mjs --update-existing`.
 - `shell_model.py`: boundary parser from a tool call (Claude/Cursor
   `command`, Codex `cmd`, argv lists, and Codex's JavaScript-wrapped
   `exec_command({...})`) to `Command(argv, cwd)` values, following `cd`
-  and explicit `workdir`.
+  and explicit `workdir`. A quoted argument that spans lines (a multi-line
+  `git commit -m "..."`) stays one word; only a quote that never closes
+  makes the command unparseable.
 - `detect.py`: classification of commands, target-repo resolution, the
   validator call, and the pending state.
 - `claude_pretooluse.py`: the `PreToolUse` entrypoint for all three
diff --git a/engine/hooks/pr-schema-gate/shell_model.py b/engine/hooks/pr-schema-gate/shell_model.py
index 50487ee7..a40b9644 100644
--- a/engine/hooks/pr-schema-gate/shell_model.py
+++ b/engine/hooks/pr-schema-gate/shell_model.py
@@ -21,6 +21,7 @@
 
 SEPARATORS = frozenset({";", "&&", "||", "|", "&", "|&", "(", ")", ";;"})
 HEREDOC_OPERATORS = frozenset({"<<", "<<-"})
+INCOMPLETE_INPUT_ERRORS = frozenset({"No closing quotation", "No escaped character"})
 
 
 @dataclass(frozen=True)
@@ -99,6 +100,16 @@ def _tokenize(line: str) -> list[str]:
     return list(lexer)
 
 
+def _tokenize_until_quote_closes(text: str) -> list[str] | None:
+    """Tokens of `text`, or None while the input is incomplete. Any other lexer error propagates."""
+    try:
+        return _tokenize(text)
+    except ValueError as exc:
+        if str(exc) in INCOMPLETE_INPUT_ERRORS:
+            return None
+        raise
+
+
 def _logical_lines(script: str) -> list[str]:
     lines: list[str] = []
     pending = ""
@@ -127,9 +138,14 @@ def _heredoc_delimiters(tokens: list[str]) -> list[tuple[str, bool]]:
 
 
 def _token_lines(script: str) -> list[list[str]] | None:
-    """Tokenize each logical line, dropping heredoc bodies. None if any line cannot be lexed."""
+    """Tokenize each logical line, dropping heredoc bodies. None if a quote never closes.
+
+    A line that cannot be lexed alone opens a quote; the following lines join it
+    until the quote closes, so a quoted argument spanning lines stays one word.
+    """
     result: list[list[str]] = []
     waiting: list[tuple[str, bool]] = []
+    open_quote: str | None = None
     for line in _logical_lines(script):
         if waiting:
             delimiter, strip_tabs = waiting[0]
@@ -137,13 +153,15 @@ def _token_lines(script: str) -> list[list[str]] | None:
             if candidate.strip() == delimiter:
                 waiting.pop(0)
             continue
-        try:
-            tokens = _tokenize(line)
-        except ValueError:
-            return None
-        waiting.extend(_heredoc_delimiters(tokens))
-        result.append(tokens)
-    return result
+        text = line if open_quote is None else open_quote + "\n" + line
+        tokens = _tokenize_until_quote_closes(text)
+        if tokens is None:
+            open_quote = text
+        else:
+            open_quote = None
+            waiting.extend(_heredoc_delimiters(tokens))
+            result.append(tokens)
+    return None if open_quote is not None else result
 
 
 def _is_assignment(word: str) -> bool:
diff --git a/engine/hooks/pr-schema-gate/tests/test_multiline_quotes.py b/engine/hooks/pr-schema-gate/tests/test_multiline_quotes.py
new file mode 100644
index 00000000..44bd7ac5
--- /dev/null
+++ b/engine/hooks/pr-schema-gate/tests/test_multiline_quotes.py
@@ -0,0 +1,81 @@
+"""A quoted argument that spans lines is one word, not an unparseable command.
+
+The payload is the real command that drew a false "could not parse" advisory:
+a heredoc, then a `git commit -am "<subject>\n\n<trailers>"` whose message spans
+three lines.
+"""
+from __future__ import annotations
+
+import io
+import json
+import os
+import sys
+import tempfile
+import unittest
+from contextlib import redirect_stderr, redirect_stdout
+
+sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)), ".."))
+import claude_pretooluse  # noqa: E402
+import detect  # noqa: E402
+from shell_model import ShellCall, parse_commands  # noqa: E402
+
+MESSAGE = (
+    "principle-explicit-errors: drop an unobserved count from the example\n\n"
+    "Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>\n"
+    "Claude-Session: https://claude.ai/code/session_01WSVNdBBo7dFqoR8Tx521EJ"
+)
+REAL_COMMAND = (
+    "cd /work && python3 - <<'EOF'\n"
+    "p = \"tests/fires_example.md\"\n"
+    "open(p, \"w\").write(\"x\")\n"
+    "EOF\n"
+    "grep -n \"rewords\" tests/fires_example.md && git commit -q -am \"" + MESSAGE + "\" && git log --oneline -2"
+)
+
+
+class TestMultilineQuotedArguments(unittest.TestCase):
+    def test_real_multiline_commit_message_parses(self):
+        commands = parse_commands(ShellCall(REAL_COMMAND, None), "/s")
+        self.assertIsNotNone(commands)
+        argvs = [c.argv for c in commands]
+        self.assertIn(("git", "commit", "-q", "-am", MESSAGE), argvs)
+        self.assertIn(("git", "log", "--oneline", "-2"), argvs)
+        self.assertIn(("grep", "-n", "rewords", "tests/fires_example.md"), argvs)
+
+    def test_single_quoted_multiline_argument_parses(self):
+        commands = parse_commands(ShellCall("echo 'one\ntwo'\necho three", None), "/s")
+        self.assertEqual([c.argv for c in commands], [("echo", "one\ntwo"), ("echo", "three")])
+
+    def test_quote_never_closed_is_still_unparseable(self):
+        self.assertIsNone(parse_commands(ShellCall("echo 'one\ntwo\nthree", None), "/s"))
+
+    def test_unclosed_quote_ending_in_a_backslash_is_unparseable_not_an_error(self):
+        self.assertIsNone(parse_commands(ShellCall('echo "a\\', None), "/s"))
+
+    def test_trailing_backslash_outside_quotes_is_a_line_continuation(self):
+        commands = parse_commands(ShellCall("echo done \\", None), "/s")
+        self.assertEqual([c.argv for c in commands], [("echo", "done")])
+
+    def test_hook_is_silent_on_the_real_command_in_scope(self):
+        with tempfile.TemporaryDirectory() as repo:
+            os.makedirs(os.path.join(repo, "scripts"))
+            os.makedirs(os.path.join(repo, ".git"))
+            open(os.path.join(repo, "scripts", "create-pr.mjs"), "w").close()
+            state = tempfile.TemporaryDirectory()
+            self.addCleanup(state.cleanup)
+            os.environ[detect.STATE_DIR_ENV] = state.name
+            self.addCleanup(os.environ.pop, detect.STATE_DIR_ENV, None)
+            payload = {"tool_name": "Bash", "tool_input": {"command": REAL_COMMAND}, "cwd": repo}
+            err, out = io.StringIO(), io.StringIO()
+            old = sys.stdin
+            sys.stdin = io.StringIO(json.dumps(payload))
+            try:
+                with redirect_stderr(err), redirect_stdout(out):
+                    claude_pretooluse.main()
+            finally:
+                sys.stdin = old
+            self.assertEqual((err.getvalue(), out.getvalue()), ("", ""))
+
+
+if __name__ == "__main__":
+    unittest.main()