(Claude) Session previews: skip leading YAML front matter

claude_code_log/utils.py

@@ -740,6 +740,17 @@ def create_session_preview(text_content: str) -> str:
         flags=re.DOTALL,
     ).strip()
 
+    # Skip leading YAML front matter, as the rendering does: the preview
+    # starts at the body. Front matter alone leaves an empty preview. The
+    # import is lazy (it brings in PyYAML), and only text that could open
+    # with front matter pays for it.
+    if preview_content.startswith("---"):
+        from .frontmatter import split_frontmatter
+
+        split = split_frontmatter(preview_content)
+        if split is not None:
+            preview_content = split[1].strip()
+
     # Strip command-tag XML soup down to ``/cmd`` or inner-text shape.
     preview_content = simplify_command_tags(preview_content)
 

test/test_session_preview_frontmatter.py

@@ -0,0 +1,93 @@
+"""A session preview skips the first message's leading YAML front matter.
+
+The preview (the first user message's label in the table of contents,
+the index cards and the TUI) starts at the body, as the rendering shows
+it. It uses the rendering's own detector, so a ``---`` followed by a
+blank line is a horizontal rule and stays in the preview. A message
+holding only front matter gives an empty preview, and the next user
+message supplies it, as for any empty first message.
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+from typing import Any
+
+import pytest
+
+from claude_code_log.converter import compute_session_data, load_transcript
+from claude_code_log.renderer import _collect_session_info
+from claude_code_log.utils import create_session_preview
+
+FRONT_MATTER = "---\nname: release-checklist\ndescription: steps\n---\n\n"
+BODY = "Please tag the release once CI is green."
+
+
+class TestCreateSessionPreview:
+    def test_front_matter_is_skipped(self) -> None:
+        assert create_session_preview(FRONT_MATTER + BODY) == BODY
+
+    def test_front_matter_only_is_empty(self) -> None:
+        assert create_session_preview("---\nonly: front matter\n---\n") == ""
+
+    def test_a_leading_rule_is_unchanged(self) -> None:
+        text = "---\n\nA rule first, then text."
+        assert create_session_preview(text) == text
+
+    def test_ordinary_previews_are_unchanged(self) -> None:
+        assert create_session_preview(BODY) == BODY
+        assert create_session_preview("A note\n---\nlate: block\n---") == (
+            "A note\n---\nlate: block\n---"
+        )
+
+    def test_front_matter_after_a_system_reminder(self) -> None:
+        # The reminder is not part of the rendered text, so the front
+        # matter is still at its start.
+        text = "<system-reminder>context</system-reminder>\n" + FRONT_MATTER + BODY
+        assert create_session_preview(text) == BODY
+
+
+def _user(uuid: str, parent: str | None, minute: int, text: str) -> dict[str, Any]:
+    return {
+        "type": "user",
+        "timestamp": f"2026-04-19T10:{minute:02d}:00.000Z",
+        "parentUuid": parent,
+        "uuid": uuid,
+        "isSidechain": False,
+        "userType": "external",
+        "cwd": "/tmp",
+        "sessionId": "s1",
+        "version": "2.1.34",
+        "message": {"role": "user", "content": text},
+    }
+
+
+@pytest.fixture
+def messages(tmp_path: Path, request: pytest.FixtureRequest) -> Any:
+    first, second = request.param
+    entries = [_user("u1", None, 0, first), _user("u2", "u1", 1, second)]
+    path = tmp_path / "s1.jsonl"
+    path.write_text("\n".join(json.dumps(e) for e in entries) + "\n", encoding="utf-8")
+    return load_transcript(path)
+
+
+CASES = [
+    pytest.param((FRONT_MATTER + BODY, "A later question."), BODY, id="front-matter"),
+    pytest.param(
+        ("---\nonly: front matter\n---\n", "A later question."),
+        "A later question.",
+        id="front-matter-only",
+    ),
+    pytest.param((BODY, "A later question."), BODY, id="ordinary"),
+]
+
+
+@pytest.mark.parametrize(("messages", "expected"), CASES, indirect=["messages"])
+class TestSessionPreviews:
+    def test_cached_session_data(self, messages: Any, expected: str) -> None:
+        assert compute_session_data(messages)["s1"].first_user_message == expected
+
+    def test_session_navigation(self, messages: Any, expected: str) -> None:
+        sessions, _, _ = _collect_session_info(messages, {})
+        assert sessions["s1"]["first_user_message"] == expected