diff --git a/clients/deadline.py b/clients/deadline.py
index c0cfc94..eeb9770 100644
--- a/clients/deadline.py
+++ b/clients/deadline.py
@@ -29,6 +29,10 @@ def elapsed(self) -> float:
         """Return seconds since start; uncapped, may exceed timeout."""
         return self._clock.monotonic() - self._started_at
 
+    def elapsed_ms(self) -> float:
+        """Return milliseconds since start; uncapped, may exceed timeout."""
+        return self.elapsed() * 1000
+
     def fraction_used(self) -> float:
         """Return elapsed/timeout clamped to [0, 1]; timeout==0 yields 1.0."""
         if self._timeout == 0:
diff --git a/scenarios/cli.py b/scenarios/cli.py
index 2e51c8f..9d2b999 100644
--- a/scenarios/cli.py
+++ b/scenarios/cli.py
@@ -84,6 +84,12 @@ def build_parser() -> argparse.ArgumentParser:
         "find", help="Find scenarios by id or description substring"
     )
     find_parser.add_argument("query", help="Case-insensitive match on id or description")
+    find_parser.add_argument(
+        "--format",
+        choices=("text", "json"),
+        default="text",
+        help="Output format (default: text)",
+    )
     return parser
 
 
@@ -210,11 +216,12 @@ def main(argv: list[str] | None = None) -> int:
             if query in entry.scenario_id.casefold()
             or query in entry.description.casefold()
         ]
-        if not matches:
-            return 1
-        for scenario_id in matches:
-            print(scenario_id)
-        return 0
+        if args.format == "json":
+            print(json.dumps(matches, indent=2))
+        else:
+            for scenario_id in matches:
+                print(scenario_id)
+        return 0 if matches else 1
 
     return 1
 
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 19556a5..979cc65 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -275,6 +275,30 @@ def test_find_no_matches_returns_error(self):
         self.assertEqual(code, 1)
         self.assertEqual(buffer.getvalue().strip(), "")
 
+    def test_find_json_format(self):
+        buffer = io.StringIO()
+        with redirect_stdout(buffer):
+            code = main(["find", "CIRCUIT-BREAKER", "--format", "json"])
+        self.assertEqual(code, 0)
+        parsed = json.loads(buffer.getvalue())
+        self.assertEqual(parsed, ["circuit-breaker"])
+
+    def test_find_text_format_default_unchanged(self):
+        buffer = io.StringIO()
+        with redirect_stdout(buffer):
+            code = main(["find", "CIRCUIT-BREAKER", "--format", "text"])
+        self.assertEqual(code, 0)
+        lines = [line for line in buffer.getvalue().splitlines() if line.strip()]
+        self.assertEqual(lines, ["circuit-breaker"])
+
+    def test_find_json_no_matches_returns_empty_array(self):
+        buffer = io.StringIO()
+        with redirect_stdout(buffer):
+            code = main(["find", "zzzz-no-such", "--format", "json"])
+        self.assertEqual(code, 1)
+        parsed = json.loads(buffer.getvalue())
+        self.assertEqual(parsed, [])
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/test_deadline.py b/tests/test_deadline.py
index 7890cdf..a3b6627 100644
--- a/tests/test_deadline.py
+++ b/tests/test_deadline.py
@@ -51,6 +51,16 @@ def test_elapsed_tracks_fake_clock_uncapped(self):
         self.assertAlmostEqual(deadline.elapsed(), 0.8)
         self.assertGreater(deadline.elapsed(), 0.5)
 
+    def test_elapsed_ms_tracks_fake_clock_uncapped(self):
+        clock = FakeClock()
+        deadline = Deadline(clock, timeout=0.5)
+        self.assertAlmostEqual(deadline.elapsed_ms(), 0.0)
+        clock.sleep(0.4)
+        self.assertAlmostEqual(deadline.elapsed_ms(), 400.0)
+        clock.sleep(0.4)
+        self.assertAlmostEqual(deadline.elapsed_ms(), 800.0)
+        self.assertGreater(deadline.elapsed_ms(), 500.0)
+
     def test_fraction_used_clamped_to_unit_interval(self):
         clock = FakeClock()
         deadline = Deadline(clock, timeout=1.0)