From 2ba7882653500a35a4be3ef4785fd95c11199480 Mon Sep 17 00:00:00 2001
From: fan wu <336798967+FanWu-ai@users.noreply.github.com>
Date: Sun, 11 Oct 2026 10:25:45 -0700
Subject: [PATCH] Reset per-report state when reusing a Speedscope renderer

AI assistance: OpenAI Codex was used for investigation, implementation, regression tests, and automated validation.
---
 pyinstrument/renderers/speedscope.py |  2 ++
 test/test_renderers.py               | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/pyinstrument/renderers/speedscope.py b/pyinstrument/renderers/speedscope.py
index 6bb20581..37d0f5b6 100644
--- a/pyinstrument/renderers/speedscope.py
+++ b/pyinstrument/renderers/speedscope.py
@@ -207,6 +207,8 @@ def render_frame(self, frame: Frame | None) -> list[SpeedscopeEvent]:
         return events_array
 
     def render(self, session: Session):
+        self._event_time = 0.0
+        self._frame_to_index.clear()
         frame = self.preprocess(session.root_frame())
 
         id_: str = time.strftime("%Y-%m-%dT%H-%M-%S", time.localtime(session.start_time))
diff --git a/test/test_renderers.py b/test/test_renderers.py
index 87ba4456..9270c0c0 100644
--- a/test/test_renderers.py
+++ b/test/test_renderers.py
@@ -89,6 +89,29 @@ def test_show_all_doesnt_crash(
     renderer.render(profiler_session)
 
 
+def test_speedscope_renderer_reused_with_same_session(profiler_session):
+    renderer = renderers.SpeedscopeRenderer()
+    first_output = renderer.render(profiler_session)
+    assert renderer.render(profiler_session) == first_output
+
+
+@pytest.mark.parametrize("empty", [False, True])
+def test_speedscope_renderer_reused_with_different_session(profiler_session, empty):
+    session_data = profiler_session.to_json()
+    session_data.update(
+        frame_records=[] if empty else [(["other\x00other.py\x001"], 0.25)],
+        start_call_stack=[],
+        duration=0 if empty else 0.25,
+        sample_count=0 if empty else 1,
+        cpu_time=0 if empty else 0.25,
+    )
+    next_session = Session.from_json(session_data)
+
+    renderer = renderers.SpeedscopeRenderer()
+    renderer.render(profiler_session)
+    assert renderer.render(next_session) == renderers.SpeedscopeRenderer().render(next_session)
+
+
 @pytest.mark.parametrize("flat_time", ["self", "total"])
 def test_console_renderer_flat_doesnt_crash(profiler_session, flat_time):
     renderer = renderers.ConsoleRenderer(flat=True, flat_time=flat_time)